Merge tag 'acpi-4.14-rc1' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael...
[sfrench/cifs-2.6.git] / drivers / spi / spi.c
1 /*
2  * SPI init/core code
3  *
4  * Copyright (C) 2005 David Brownell
5  * Copyright (C) 2008 Secret Lab Technologies Ltd.
6  *
7  * This program is free software; you can redistribute it and/or modify
8  * it under the terms of the GNU General Public License as published by
9  * the Free Software Foundation; either version 2 of the License, or
10  * (at your option) any later version.
11  *
12  * This program is distributed in the hope that it will be useful,
13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
15  * GNU General Public License for more details.
16  */
17
18 #include <linux/kernel.h>
19 #include <linux/device.h>
20 #include <linux/init.h>
21 #include <linux/cache.h>
22 #include <linux/dma-mapping.h>
23 #include <linux/dmaengine.h>
24 #include <linux/mutex.h>
25 #include <linux/of_device.h>
26 #include <linux/of_irq.h>
27 #include <linux/clk/clk-conf.h>
28 #include <linux/slab.h>
29 #include <linux/mod_devicetable.h>
30 #include <linux/spi/spi.h>
31 #include <linux/of_gpio.h>
32 #include <linux/pm_runtime.h>
33 #include <linux/pm_domain.h>
34 #include <linux/property.h>
35 #include <linux/export.h>
36 #include <linux/sched/rt.h>
37 #include <uapi/linux/sched/types.h>
38 #include <linux/delay.h>
39 #include <linux/kthread.h>
40 #include <linux/ioport.h>
41 #include <linux/acpi.h>
42 #include <linux/highmem.h>
43 #include <linux/idr.h>
44 #include <linux/platform_data/x86/apple.h>
45
46 #define CREATE_TRACE_POINTS
47 #include <trace/events/spi.h>
48 #define SPI_DYN_FIRST_BUS_NUM 0
49
50 static DEFINE_IDR(spi_master_idr);
51
52 static void spidev_release(struct device *dev)
53 {
54         struct spi_device       *spi = to_spi_device(dev);
55
56         /* spi controllers may cleanup for released devices */
57         if (spi->controller->cleanup)
58                 spi->controller->cleanup(spi);
59
60         spi_controller_put(spi->controller);
61         kfree(spi);
62 }
63
64 static ssize_t
65 modalias_show(struct device *dev, struct device_attribute *a, char *buf)
66 {
67         const struct spi_device *spi = to_spi_device(dev);
68         int len;
69
70         len = acpi_device_modalias(dev, buf, PAGE_SIZE - 1);
71         if (len != -ENODEV)
72                 return len;
73
74         return sprintf(buf, "%s%s\n", SPI_MODULE_PREFIX, spi->modalias);
75 }
76 static DEVICE_ATTR_RO(modalias);
77
78 #define SPI_STATISTICS_ATTRS(field, file)                               \
79 static ssize_t spi_controller_##field##_show(struct device *dev,        \
80                                              struct device_attribute *attr, \
81                                              char *buf)                 \
82 {                                                                       \
83         struct spi_controller *ctlr = container_of(dev,                 \
84                                          struct spi_controller, dev);   \
85         return spi_statistics_##field##_show(&ctlr->statistics, buf);   \
86 }                                                                       \
87 static struct device_attribute dev_attr_spi_controller_##field = {      \
88         .attr = { .name = file, .mode = 0444 },                         \
89         .show = spi_controller_##field##_show,                          \
90 };                                                                      \
91 static ssize_t spi_device_##field##_show(struct device *dev,            \
92                                          struct device_attribute *attr, \
93                                         char *buf)                      \
94 {                                                                       \
95         struct spi_device *spi = to_spi_device(dev);                    \
96         return spi_statistics_##field##_show(&spi->statistics, buf);    \
97 }                                                                       \
98 static struct device_attribute dev_attr_spi_device_##field = {          \
99         .attr = { .name = file, .mode = 0444 },                         \
100         .show = spi_device_##field##_show,                              \
101 }
102
103 #define SPI_STATISTICS_SHOW_NAME(name, file, field, format_string)      \
104 static ssize_t spi_statistics_##name##_show(struct spi_statistics *stat, \
105                                             char *buf)                  \
106 {                                                                       \
107         unsigned long flags;                                            \
108         ssize_t len;                                                    \
109         spin_lock_irqsave(&stat->lock, flags);                          \
110         len = sprintf(buf, format_string, stat->field);                 \
111         spin_unlock_irqrestore(&stat->lock, flags);                     \
112         return len;                                                     \
113 }                                                                       \
114 SPI_STATISTICS_ATTRS(name, file)
115
116 #define SPI_STATISTICS_SHOW(field, format_string)                       \
117         SPI_STATISTICS_SHOW_NAME(field, __stringify(field),             \
118                                  field, format_string)
119
120 SPI_STATISTICS_SHOW(messages, "%lu");
121 SPI_STATISTICS_SHOW(transfers, "%lu");
122 SPI_STATISTICS_SHOW(errors, "%lu");
123 SPI_STATISTICS_SHOW(timedout, "%lu");
124
125 SPI_STATISTICS_SHOW(spi_sync, "%lu");
126 SPI_STATISTICS_SHOW(spi_sync_immediate, "%lu");
127 SPI_STATISTICS_SHOW(spi_async, "%lu");
128
129 SPI_STATISTICS_SHOW(bytes, "%llu");
130 SPI_STATISTICS_SHOW(bytes_rx, "%llu");
131 SPI_STATISTICS_SHOW(bytes_tx, "%llu");
132
133 #define SPI_STATISTICS_TRANSFER_BYTES_HISTO(index, number)              \
134         SPI_STATISTICS_SHOW_NAME(transfer_bytes_histo##index,           \
135                                  "transfer_bytes_histo_" number,        \
136                                  transfer_bytes_histo[index],  "%lu")
137 SPI_STATISTICS_TRANSFER_BYTES_HISTO(0,  "0-1");
138 SPI_STATISTICS_TRANSFER_BYTES_HISTO(1,  "2-3");
139 SPI_STATISTICS_TRANSFER_BYTES_HISTO(2,  "4-7");
140 SPI_STATISTICS_TRANSFER_BYTES_HISTO(3,  "8-15");
141 SPI_STATISTICS_TRANSFER_BYTES_HISTO(4,  "16-31");
142 SPI_STATISTICS_TRANSFER_BYTES_HISTO(5,  "32-63");
143 SPI_STATISTICS_TRANSFER_BYTES_HISTO(6,  "64-127");
144 SPI_STATISTICS_TRANSFER_BYTES_HISTO(7,  "128-255");
145 SPI_STATISTICS_TRANSFER_BYTES_HISTO(8,  "256-511");
146 SPI_STATISTICS_TRANSFER_BYTES_HISTO(9,  "512-1023");
147 SPI_STATISTICS_TRANSFER_BYTES_HISTO(10, "1024-2047");
148 SPI_STATISTICS_TRANSFER_BYTES_HISTO(11, "2048-4095");
149 SPI_STATISTICS_TRANSFER_BYTES_HISTO(12, "4096-8191");
150 SPI_STATISTICS_TRANSFER_BYTES_HISTO(13, "8192-16383");
151 SPI_STATISTICS_TRANSFER_BYTES_HISTO(14, "16384-32767");
152 SPI_STATISTICS_TRANSFER_BYTES_HISTO(15, "32768-65535");
153 SPI_STATISTICS_TRANSFER_BYTES_HISTO(16, "65536+");
154
155 SPI_STATISTICS_SHOW(transfers_split_maxsize, "%lu");
156
157 static struct attribute *spi_dev_attrs[] = {
158         &dev_attr_modalias.attr,
159         NULL,
160 };
161
162 static const struct attribute_group spi_dev_group = {
163         .attrs  = spi_dev_attrs,
164 };
165
166 static struct attribute *spi_device_statistics_attrs[] = {
167         &dev_attr_spi_device_messages.attr,
168         &dev_attr_spi_device_transfers.attr,
169         &dev_attr_spi_device_errors.attr,
170         &dev_attr_spi_device_timedout.attr,
171         &dev_attr_spi_device_spi_sync.attr,
172         &dev_attr_spi_device_spi_sync_immediate.attr,
173         &dev_attr_spi_device_spi_async.attr,
174         &dev_attr_spi_device_bytes.attr,
175         &dev_attr_spi_device_bytes_rx.attr,
176         &dev_attr_spi_device_bytes_tx.attr,
177         &dev_attr_spi_device_transfer_bytes_histo0.attr,
178         &dev_attr_spi_device_transfer_bytes_histo1.attr,
179         &dev_attr_spi_device_transfer_bytes_histo2.attr,
180         &dev_attr_spi_device_transfer_bytes_histo3.attr,
181         &dev_attr_spi_device_transfer_bytes_histo4.attr,
182         &dev_attr_spi_device_transfer_bytes_histo5.attr,
183         &dev_attr_spi_device_transfer_bytes_histo6.attr,
184         &dev_attr_spi_device_transfer_bytes_histo7.attr,
185         &dev_attr_spi_device_transfer_bytes_histo8.attr,
186         &dev_attr_spi_device_transfer_bytes_histo9.attr,
187         &dev_attr_spi_device_transfer_bytes_histo10.attr,
188         &dev_attr_spi_device_transfer_bytes_histo11.attr,
189         &dev_attr_spi_device_transfer_bytes_histo12.attr,
190         &dev_attr_spi_device_transfer_bytes_histo13.attr,
191         &dev_attr_spi_device_transfer_bytes_histo14.attr,
192         &dev_attr_spi_device_transfer_bytes_histo15.attr,
193         &dev_attr_spi_device_transfer_bytes_histo16.attr,
194         &dev_attr_spi_device_transfers_split_maxsize.attr,
195         NULL,
196 };
197
198 static const struct attribute_group spi_device_statistics_group = {
199         .name  = "statistics",
200         .attrs  = spi_device_statistics_attrs,
201 };
202
203 static const struct attribute_group *spi_dev_groups[] = {
204         &spi_dev_group,
205         &spi_device_statistics_group,
206         NULL,
207 };
208
209 static struct attribute *spi_controller_statistics_attrs[] = {
210         &dev_attr_spi_controller_messages.attr,
211         &dev_attr_spi_controller_transfers.attr,
212         &dev_attr_spi_controller_errors.attr,
213         &dev_attr_spi_controller_timedout.attr,
214         &dev_attr_spi_controller_spi_sync.attr,
215         &dev_attr_spi_controller_spi_sync_immediate.attr,
216         &dev_attr_spi_controller_spi_async.attr,
217         &dev_attr_spi_controller_bytes.attr,
218         &dev_attr_spi_controller_bytes_rx.attr,
219         &dev_attr_spi_controller_bytes_tx.attr,
220         &dev_attr_spi_controller_transfer_bytes_histo0.attr,
221         &dev_attr_spi_controller_transfer_bytes_histo1.attr,
222         &dev_attr_spi_controller_transfer_bytes_histo2.attr,
223         &dev_attr_spi_controller_transfer_bytes_histo3.attr,
224         &dev_attr_spi_controller_transfer_bytes_histo4.attr,
225         &dev_attr_spi_controller_transfer_bytes_histo5.attr,
226         &dev_attr_spi_controller_transfer_bytes_histo6.attr,
227         &dev_attr_spi_controller_transfer_bytes_histo7.attr,
228         &dev_attr_spi_controller_transfer_bytes_histo8.attr,
229         &dev_attr_spi_controller_transfer_bytes_histo9.attr,
230         &dev_attr_spi_controller_transfer_bytes_histo10.attr,
231         &dev_attr_spi_controller_transfer_bytes_histo11.attr,
232         &dev_attr_spi_controller_transfer_bytes_histo12.attr,
233         &dev_attr_spi_controller_transfer_bytes_histo13.attr,
234         &dev_attr_spi_controller_transfer_bytes_histo14.attr,
235         &dev_attr_spi_controller_transfer_bytes_histo15.attr,
236         &dev_attr_spi_controller_transfer_bytes_histo16.attr,
237         &dev_attr_spi_controller_transfers_split_maxsize.attr,
238         NULL,
239 };
240
241 static const struct attribute_group spi_controller_statistics_group = {
242         .name  = "statistics",
243         .attrs  = spi_controller_statistics_attrs,
244 };
245
246 static const struct attribute_group *spi_master_groups[] = {
247         &spi_controller_statistics_group,
248         NULL,
249 };
250
251 void spi_statistics_add_transfer_stats(struct spi_statistics *stats,
252                                        struct spi_transfer *xfer,
253                                        struct spi_controller *ctlr)
254 {
255         unsigned long flags;
256         int l2len = min(fls(xfer->len), SPI_STATISTICS_HISTO_SIZE) - 1;
257
258         if (l2len < 0)
259                 l2len = 0;
260
261         spin_lock_irqsave(&stats->lock, flags);
262
263         stats->transfers++;
264         stats->transfer_bytes_histo[l2len]++;
265
266         stats->bytes += xfer->len;
267         if ((xfer->tx_buf) &&
268             (xfer->tx_buf != ctlr->dummy_tx))
269                 stats->bytes_tx += xfer->len;
270         if ((xfer->rx_buf) &&
271             (xfer->rx_buf != ctlr->dummy_rx))
272                 stats->bytes_rx += xfer->len;
273
274         spin_unlock_irqrestore(&stats->lock, flags);
275 }
276 EXPORT_SYMBOL_GPL(spi_statistics_add_transfer_stats);
277
278 /* modalias support makes "modprobe $MODALIAS" new-style hotplug work,
279  * and the sysfs version makes coldplug work too.
280  */
281
282 static const struct spi_device_id *spi_match_id(const struct spi_device_id *id,
283                                                 const struct spi_device *sdev)
284 {
285         while (id->name[0]) {
286                 if (!strcmp(sdev->modalias, id->name))
287                         return id;
288                 id++;
289         }
290         return NULL;
291 }
292
293 const struct spi_device_id *spi_get_device_id(const struct spi_device *sdev)
294 {
295         const struct spi_driver *sdrv = to_spi_driver(sdev->dev.driver);
296
297         return spi_match_id(sdrv->id_table, sdev);
298 }
299 EXPORT_SYMBOL_GPL(spi_get_device_id);
300
301 static int spi_match_device(struct device *dev, struct device_driver *drv)
302 {
303         const struct spi_device *spi = to_spi_device(dev);
304         const struct spi_driver *sdrv = to_spi_driver(drv);
305
306         /* Attempt an OF style match */
307         if (of_driver_match_device(dev, drv))
308                 return 1;
309
310         /* Then try ACPI */
311         if (acpi_driver_match_device(dev, drv))
312                 return 1;
313
314         if (sdrv->id_table)
315                 return !!spi_match_id(sdrv->id_table, spi);
316
317         return strcmp(spi->modalias, drv->name) == 0;
318 }
319
320 static int spi_uevent(struct device *dev, struct kobj_uevent_env *env)
321 {
322         const struct spi_device         *spi = to_spi_device(dev);
323         int rc;
324
325         rc = acpi_device_uevent_modalias(dev, env);
326         if (rc != -ENODEV)
327                 return rc;
328
329         return add_uevent_var(env, "MODALIAS=%s%s", SPI_MODULE_PREFIX, spi->modalias);
330 }
331
332 struct bus_type spi_bus_type = {
333         .name           = "spi",
334         .dev_groups     = spi_dev_groups,
335         .match          = spi_match_device,
336         .uevent         = spi_uevent,
337 };
338 EXPORT_SYMBOL_GPL(spi_bus_type);
339
340
341 static int spi_drv_probe(struct device *dev)
342 {
343         const struct spi_driver         *sdrv = to_spi_driver(dev->driver);
344         struct spi_device               *spi = to_spi_device(dev);
345         int ret;
346
347         ret = of_clk_set_defaults(dev->of_node, false);
348         if (ret)
349                 return ret;
350
351         if (dev->of_node) {
352                 spi->irq = of_irq_get(dev->of_node, 0);
353                 if (spi->irq == -EPROBE_DEFER)
354                         return -EPROBE_DEFER;
355                 if (spi->irq < 0)
356                         spi->irq = 0;
357         }
358
359         ret = dev_pm_domain_attach(dev, true);
360         if (ret != -EPROBE_DEFER) {
361                 ret = sdrv->probe(spi);
362                 if (ret)
363                         dev_pm_domain_detach(dev, true);
364         }
365
366         return ret;
367 }
368
369 static int spi_drv_remove(struct device *dev)
370 {
371         const struct spi_driver         *sdrv = to_spi_driver(dev->driver);
372         int ret;
373
374         ret = sdrv->remove(to_spi_device(dev));
375         dev_pm_domain_detach(dev, true);
376
377         return ret;
378 }
379
380 static void spi_drv_shutdown(struct device *dev)
381 {
382         const struct spi_driver         *sdrv = to_spi_driver(dev->driver);
383
384         sdrv->shutdown(to_spi_device(dev));
385 }
386
387 /**
388  * __spi_register_driver - register a SPI driver
389  * @owner: owner module of the driver to register
390  * @sdrv: the driver to register
391  * Context: can sleep
392  *
393  * Return: zero on success, else a negative error code.
394  */
395 int __spi_register_driver(struct module *owner, struct spi_driver *sdrv)
396 {
397         sdrv->driver.owner = owner;
398         sdrv->driver.bus = &spi_bus_type;
399         if (sdrv->probe)
400                 sdrv->driver.probe = spi_drv_probe;
401         if (sdrv->remove)
402                 sdrv->driver.remove = spi_drv_remove;
403         if (sdrv->shutdown)
404                 sdrv->driver.shutdown = spi_drv_shutdown;
405         return driver_register(&sdrv->driver);
406 }
407 EXPORT_SYMBOL_GPL(__spi_register_driver);
408
409 /*-------------------------------------------------------------------------*/
410
411 /* SPI devices should normally not be created by SPI device drivers; that
412  * would make them board-specific.  Similarly with SPI controller drivers.
413  * Device registration normally goes into like arch/.../mach.../board-YYY.c
414  * with other readonly (flashable) information about mainboard devices.
415  */
416
417 struct boardinfo {
418         struct list_head        list;
419         struct spi_board_info   board_info;
420 };
421
422 static LIST_HEAD(board_list);
423 static LIST_HEAD(spi_controller_list);
424
425 /*
426  * Used to protect add/del opertion for board_info list and
427  * spi_controller list, and their matching process
428  * also used to protect object of type struct idr
429  */
430 static DEFINE_MUTEX(board_lock);
431
432 /**
433  * spi_alloc_device - Allocate a new SPI device
434  * @ctlr: Controller to which device is connected
435  * Context: can sleep
436  *
437  * Allows a driver to allocate and initialize a spi_device without
438  * registering it immediately.  This allows a driver to directly
439  * fill the spi_device with device parameters before calling
440  * spi_add_device() on it.
441  *
442  * Caller is responsible to call spi_add_device() on the returned
443  * spi_device structure to add it to the SPI controller.  If the caller
444  * needs to discard the spi_device without adding it, then it should
445  * call spi_dev_put() on it.
446  *
447  * Return: a pointer to the new device, or NULL.
448  */
449 struct spi_device *spi_alloc_device(struct spi_controller *ctlr)
450 {
451         struct spi_device       *spi;
452
453         if (!spi_controller_get(ctlr))
454                 return NULL;
455
456         spi = kzalloc(sizeof(*spi), GFP_KERNEL);
457         if (!spi) {
458                 spi_controller_put(ctlr);
459                 return NULL;
460         }
461
462         spi->master = spi->controller = ctlr;
463         spi->dev.parent = &ctlr->dev;
464         spi->dev.bus = &spi_bus_type;
465         spi->dev.release = spidev_release;
466         spi->cs_gpio = -ENOENT;
467
468         spin_lock_init(&spi->statistics.lock);
469
470         device_initialize(&spi->dev);
471         return spi;
472 }
473 EXPORT_SYMBOL_GPL(spi_alloc_device);
474
475 static void spi_dev_set_name(struct spi_device *spi)
476 {
477         struct acpi_device *adev = ACPI_COMPANION(&spi->dev);
478
479         if (adev) {
480                 dev_set_name(&spi->dev, "spi-%s", acpi_dev_name(adev));
481                 return;
482         }
483
484         dev_set_name(&spi->dev, "%s.%u", dev_name(&spi->controller->dev),
485                      spi->chip_select);
486 }
487
488 static int spi_dev_check(struct device *dev, void *data)
489 {
490         struct spi_device *spi = to_spi_device(dev);
491         struct spi_device *new_spi = data;
492
493         if (spi->controller == new_spi->controller &&
494             spi->chip_select == new_spi->chip_select)
495                 return -EBUSY;
496         return 0;
497 }
498
499 /**
500  * spi_add_device - Add spi_device allocated with spi_alloc_device
501  * @spi: spi_device to register
502  *
503  * Companion function to spi_alloc_device.  Devices allocated with
504  * spi_alloc_device can be added onto the spi bus with this function.
505  *
506  * Return: 0 on success; negative errno on failure
507  */
508 int spi_add_device(struct spi_device *spi)
509 {
510         static DEFINE_MUTEX(spi_add_lock);
511         struct spi_controller *ctlr = spi->controller;
512         struct device *dev = ctlr->dev.parent;
513         int status;
514
515         /* Chipselects are numbered 0..max; validate. */
516         if (spi->chip_select >= ctlr->num_chipselect) {
517                 dev_err(dev, "cs%d >= max %d\n", spi->chip_select,
518                         ctlr->num_chipselect);
519                 return -EINVAL;
520         }
521
522         /* Set the bus ID string */
523         spi_dev_set_name(spi);
524
525         /* We need to make sure there's no other device with this
526          * chipselect **BEFORE** we call setup(), else we'll trash
527          * its configuration.  Lock against concurrent add() calls.
528          */
529         mutex_lock(&spi_add_lock);
530
531         status = bus_for_each_dev(&spi_bus_type, NULL, spi, spi_dev_check);
532         if (status) {
533                 dev_err(dev, "chipselect %d already in use\n",
534                                 spi->chip_select);
535                 goto done;
536         }
537
538         if (ctlr->cs_gpios)
539                 spi->cs_gpio = ctlr->cs_gpios[spi->chip_select];
540
541         /* Drivers may modify this initial i/o setup, but will
542          * normally rely on the device being setup.  Devices
543          * using SPI_CS_HIGH can't coexist well otherwise...
544          */
545         status = spi_setup(spi);
546         if (status < 0) {
547                 dev_err(dev, "can't setup %s, status %d\n",
548                                 dev_name(&spi->dev), status);
549                 goto done;
550         }
551
552         /* Device may be bound to an active driver when this returns */
553         status = device_add(&spi->dev);
554         if (status < 0)
555                 dev_err(dev, "can't add %s, status %d\n",
556                                 dev_name(&spi->dev), status);
557         else
558                 dev_dbg(dev, "registered child %s\n", dev_name(&spi->dev));
559
560 done:
561         mutex_unlock(&spi_add_lock);
562         return status;
563 }
564 EXPORT_SYMBOL_GPL(spi_add_device);
565
566 /**
567  * spi_new_device - instantiate one new SPI device
568  * @ctlr: Controller to which device is connected
569  * @chip: Describes the SPI device
570  * Context: can sleep
571  *
572  * On typical mainboards, this is purely internal; and it's not needed
573  * after board init creates the hard-wired devices.  Some development
574  * platforms may not be able to use spi_register_board_info though, and
575  * this is exported so that for example a USB or parport based adapter
576  * driver could add devices (which it would learn about out-of-band).
577  *
578  * Return: the new device, or NULL.
579  */
580 struct spi_device *spi_new_device(struct spi_controller *ctlr,
581                                   struct spi_board_info *chip)
582 {
583         struct spi_device       *proxy;
584         int                     status;
585
586         /* NOTE:  caller did any chip->bus_num checks necessary.
587          *
588          * Also, unless we change the return value convention to use
589          * error-or-pointer (not NULL-or-pointer), troubleshootability
590          * suggests syslogged diagnostics are best here (ugh).
591          */
592
593         proxy = spi_alloc_device(ctlr);
594         if (!proxy)
595                 return NULL;
596
597         WARN_ON(strlen(chip->modalias) >= sizeof(proxy->modalias));
598
599         proxy->chip_select = chip->chip_select;
600         proxy->max_speed_hz = chip->max_speed_hz;
601         proxy->mode = chip->mode;
602         proxy->irq = chip->irq;
603         strlcpy(proxy->modalias, chip->modalias, sizeof(proxy->modalias));
604         proxy->dev.platform_data = (void *) chip->platform_data;
605         proxy->controller_data = chip->controller_data;
606         proxy->controller_state = NULL;
607
608         if (chip->properties) {
609                 status = device_add_properties(&proxy->dev, chip->properties);
610                 if (status) {
611                         dev_err(&ctlr->dev,
612                                 "failed to add properties to '%s': %d\n",
613                                 chip->modalias, status);
614                         goto err_dev_put;
615                 }
616         }
617
618         status = spi_add_device(proxy);
619         if (status < 0)
620                 goto err_remove_props;
621
622         return proxy;
623
624 err_remove_props:
625         if (chip->properties)
626                 device_remove_properties(&proxy->dev);
627 err_dev_put:
628         spi_dev_put(proxy);
629         return NULL;
630 }
631 EXPORT_SYMBOL_GPL(spi_new_device);
632
633 /**
634  * spi_unregister_device - unregister a single SPI device
635  * @spi: spi_device to unregister
636  *
637  * Start making the passed SPI device vanish. Normally this would be handled
638  * by spi_unregister_controller().
639  */
640 void spi_unregister_device(struct spi_device *spi)
641 {
642         if (!spi)
643                 return;
644
645         if (spi->dev.of_node) {
646                 of_node_clear_flag(spi->dev.of_node, OF_POPULATED);
647                 of_node_put(spi->dev.of_node);
648         }
649         if (ACPI_COMPANION(&spi->dev))
650                 acpi_device_clear_enumerated(ACPI_COMPANION(&spi->dev));
651         device_unregister(&spi->dev);
652 }
653 EXPORT_SYMBOL_GPL(spi_unregister_device);
654
655 static void spi_match_controller_to_boardinfo(struct spi_controller *ctlr,
656                                               struct spi_board_info *bi)
657 {
658         struct spi_device *dev;
659
660         if (ctlr->bus_num != bi->bus_num)
661                 return;
662
663         dev = spi_new_device(ctlr, bi);
664         if (!dev)
665                 dev_err(ctlr->dev.parent, "can't create new device for %s\n",
666                         bi->modalias);
667 }
668
669 /**
670  * spi_register_board_info - register SPI devices for a given board
671  * @info: array of chip descriptors
672  * @n: how many descriptors are provided
673  * Context: can sleep
674  *
675  * Board-specific early init code calls this (probably during arch_initcall)
676  * with segments of the SPI device table.  Any device nodes are created later,
677  * after the relevant parent SPI controller (bus_num) is defined.  We keep
678  * this table of devices forever, so that reloading a controller driver will
679  * not make Linux forget about these hard-wired devices.
680  *
681  * Other code can also call this, e.g. a particular add-on board might provide
682  * SPI devices through its expansion connector, so code initializing that board
683  * would naturally declare its SPI devices.
684  *
685  * The board info passed can safely be __initdata ... but be careful of
686  * any embedded pointers (platform_data, etc), they're copied as-is.
687  * Device properties are deep-copied though.
688  *
689  * Return: zero on success, else a negative error code.
690  */
691 int spi_register_board_info(struct spi_board_info const *info, unsigned n)
692 {
693         struct boardinfo *bi;
694         int i;
695
696         if (!n)
697                 return 0;
698
699         bi = kcalloc(n, sizeof(*bi), GFP_KERNEL);
700         if (!bi)
701                 return -ENOMEM;
702
703         for (i = 0; i < n; i++, bi++, info++) {
704                 struct spi_controller *ctlr;
705
706                 memcpy(&bi->board_info, info, sizeof(*info));
707                 if (info->properties) {
708                         bi->board_info.properties =
709                                         property_entries_dup(info->properties);
710                         if (IS_ERR(bi->board_info.properties))
711                                 return PTR_ERR(bi->board_info.properties);
712                 }
713
714                 mutex_lock(&board_lock);
715                 list_add_tail(&bi->list, &board_list);
716                 list_for_each_entry(ctlr, &spi_controller_list, list)
717                         spi_match_controller_to_boardinfo(ctlr,
718                                                           &bi->board_info);
719                 mutex_unlock(&board_lock);
720         }
721
722         return 0;
723 }
724
725 /*-------------------------------------------------------------------------*/
726
727 static void spi_set_cs(struct spi_device *spi, bool enable)
728 {
729         if (spi->mode & SPI_CS_HIGH)
730                 enable = !enable;
731
732         if (gpio_is_valid(spi->cs_gpio)) {
733                 gpio_set_value(spi->cs_gpio, !enable);
734                 /* Some SPI masters need both GPIO CS & slave_select */
735                 if ((spi->controller->flags & SPI_MASTER_GPIO_SS) &&
736                     spi->controller->set_cs)
737                         spi->controller->set_cs(spi, !enable);
738         } else if (spi->controller->set_cs) {
739                 spi->controller->set_cs(spi, !enable);
740         }
741 }
742
743 #ifdef CONFIG_HAS_DMA
744 static int spi_map_buf(struct spi_controller *ctlr, struct device *dev,
745                        struct sg_table *sgt, void *buf, size_t len,
746                        enum dma_data_direction dir)
747 {
748         const bool vmalloced_buf = is_vmalloc_addr(buf);
749         unsigned int max_seg_size = dma_get_max_seg_size(dev);
750 #ifdef CONFIG_HIGHMEM
751         const bool kmap_buf = ((unsigned long)buf >= PKMAP_BASE &&
752                                 (unsigned long)buf < (PKMAP_BASE +
753                                         (LAST_PKMAP * PAGE_SIZE)));
754 #else
755         const bool kmap_buf = false;
756 #endif
757         int desc_len;
758         int sgs;
759         struct page *vm_page;
760         struct scatterlist *sg;
761         void *sg_buf;
762         size_t min;
763         int i, ret;
764
765         if (vmalloced_buf || kmap_buf) {
766                 desc_len = min_t(int, max_seg_size, PAGE_SIZE);
767                 sgs = DIV_ROUND_UP(len + offset_in_page(buf), desc_len);
768         } else if (virt_addr_valid(buf)) {
769                 desc_len = min_t(int, max_seg_size, ctlr->max_dma_len);
770                 sgs = DIV_ROUND_UP(len, desc_len);
771         } else {
772                 return -EINVAL;
773         }
774
775         ret = sg_alloc_table(sgt, sgs, GFP_KERNEL);
776         if (ret != 0)
777                 return ret;
778
779         sg = &sgt->sgl[0];
780         for (i = 0; i < sgs; i++) {
781
782                 if (vmalloced_buf || kmap_buf) {
783                         min = min_t(size_t,
784                                     len, desc_len - offset_in_page(buf));
785                         if (vmalloced_buf)
786                                 vm_page = vmalloc_to_page(buf);
787                         else
788                                 vm_page = kmap_to_page(buf);
789                         if (!vm_page) {
790                                 sg_free_table(sgt);
791                                 return -ENOMEM;
792                         }
793                         sg_set_page(sg, vm_page,
794                                     min, offset_in_page(buf));
795                 } else {
796                         min = min_t(size_t, len, desc_len);
797                         sg_buf = buf;
798                         sg_set_buf(sg, sg_buf, min);
799                 }
800
801                 buf += min;
802                 len -= min;
803                 sg = sg_next(sg);
804         }
805
806         ret = dma_map_sg(dev, sgt->sgl, sgt->nents, dir);
807         if (!ret)
808                 ret = -ENOMEM;
809         if (ret < 0) {
810                 sg_free_table(sgt);
811                 return ret;
812         }
813
814         sgt->nents = ret;
815
816         return 0;
817 }
818
819 static void spi_unmap_buf(struct spi_controller *ctlr, struct device *dev,
820                           struct sg_table *sgt, enum dma_data_direction dir)
821 {
822         if (sgt->orig_nents) {
823                 dma_unmap_sg(dev, sgt->sgl, sgt->orig_nents, dir);
824                 sg_free_table(sgt);
825         }
826 }
827
828 static int __spi_map_msg(struct spi_controller *ctlr, struct spi_message *msg)
829 {
830         struct device *tx_dev, *rx_dev;
831         struct spi_transfer *xfer;
832         int ret;
833
834         if (!ctlr->can_dma)
835                 return 0;
836
837         if (ctlr->dma_tx)
838                 tx_dev = ctlr->dma_tx->device->dev;
839         else
840                 tx_dev = ctlr->dev.parent;
841
842         if (ctlr->dma_rx)
843                 rx_dev = ctlr->dma_rx->device->dev;
844         else
845                 rx_dev = ctlr->dev.parent;
846
847         list_for_each_entry(xfer, &msg->transfers, transfer_list) {
848                 if (!ctlr->can_dma(ctlr, msg->spi, xfer))
849                         continue;
850
851                 if (xfer->tx_buf != NULL) {
852                         ret = spi_map_buf(ctlr, tx_dev, &xfer->tx_sg,
853                                           (void *)xfer->tx_buf, xfer->len,
854                                           DMA_TO_DEVICE);
855                         if (ret != 0)
856                                 return ret;
857                 }
858
859                 if (xfer->rx_buf != NULL) {
860                         ret = spi_map_buf(ctlr, rx_dev, &xfer->rx_sg,
861                                           xfer->rx_buf, xfer->len,
862                                           DMA_FROM_DEVICE);
863                         if (ret != 0) {
864                                 spi_unmap_buf(ctlr, tx_dev, &xfer->tx_sg,
865                                               DMA_TO_DEVICE);
866                                 return ret;
867                         }
868                 }
869         }
870
871         ctlr->cur_msg_mapped = true;
872
873         return 0;
874 }
875
876 static int __spi_unmap_msg(struct spi_controller *ctlr, struct spi_message *msg)
877 {
878         struct spi_transfer *xfer;
879         struct device *tx_dev, *rx_dev;
880
881         if (!ctlr->cur_msg_mapped || !ctlr->can_dma)
882                 return 0;
883
884         if (ctlr->dma_tx)
885                 tx_dev = ctlr->dma_tx->device->dev;
886         else
887                 tx_dev = ctlr->dev.parent;
888
889         if (ctlr->dma_rx)
890                 rx_dev = ctlr->dma_rx->device->dev;
891         else
892                 rx_dev = ctlr->dev.parent;
893
894         list_for_each_entry(xfer, &msg->transfers, transfer_list) {
895                 if (!ctlr->can_dma(ctlr, msg->spi, xfer))
896                         continue;
897
898                 spi_unmap_buf(ctlr, rx_dev, &xfer->rx_sg, DMA_FROM_DEVICE);
899                 spi_unmap_buf(ctlr, tx_dev, &xfer->tx_sg, DMA_TO_DEVICE);
900         }
901
902         return 0;
903 }
904 #else /* !CONFIG_HAS_DMA */
905 static inline int spi_map_buf(struct spi_controller *ctlr, struct device *dev,
906                               struct sg_table *sgt, void *buf, size_t len,
907                               enum dma_data_direction dir)
908 {
909         return -EINVAL;
910 }
911
912 static inline void spi_unmap_buf(struct spi_controller *ctlr,
913                                  struct device *dev, struct sg_table *sgt,
914                                  enum dma_data_direction dir)
915 {
916 }
917
918 static inline int __spi_map_msg(struct spi_controller *ctlr,
919                                 struct spi_message *msg)
920 {
921         return 0;
922 }
923
924 static inline int __spi_unmap_msg(struct spi_controller *ctlr,
925                                   struct spi_message *msg)
926 {
927         return 0;
928 }
929 #endif /* !CONFIG_HAS_DMA */
930
931 static inline int spi_unmap_msg(struct spi_controller *ctlr,
932                                 struct spi_message *msg)
933 {
934         struct spi_transfer *xfer;
935
936         list_for_each_entry(xfer, &msg->transfers, transfer_list) {
937                 /*
938                  * Restore the original value of tx_buf or rx_buf if they are
939                  * NULL.
940                  */
941                 if (xfer->tx_buf == ctlr->dummy_tx)
942                         xfer->tx_buf = NULL;
943                 if (xfer->rx_buf == ctlr->dummy_rx)
944                         xfer->rx_buf = NULL;
945         }
946
947         return __spi_unmap_msg(ctlr, msg);
948 }
949
950 static int spi_map_msg(struct spi_controller *ctlr, struct spi_message *msg)
951 {
952         struct spi_transfer *xfer;
953         void *tmp;
954         unsigned int max_tx, max_rx;
955
956         if (ctlr->flags & (SPI_CONTROLLER_MUST_RX | SPI_CONTROLLER_MUST_TX)) {
957                 max_tx = 0;
958                 max_rx = 0;
959
960                 list_for_each_entry(xfer, &msg->transfers, transfer_list) {
961                         if ((ctlr->flags & SPI_CONTROLLER_MUST_TX) &&
962                             !xfer->tx_buf)
963                                 max_tx = max(xfer->len, max_tx);
964                         if ((ctlr->flags & SPI_CONTROLLER_MUST_RX) &&
965                             !xfer->rx_buf)
966                                 max_rx = max(xfer->len, max_rx);
967                 }
968
969                 if (max_tx) {
970                         tmp = krealloc(ctlr->dummy_tx, max_tx,
971                                        GFP_KERNEL | GFP_DMA);
972                         if (!tmp)
973                                 return -ENOMEM;
974                         ctlr->dummy_tx = tmp;
975                         memset(tmp, 0, max_tx);
976                 }
977
978                 if (max_rx) {
979                         tmp = krealloc(ctlr->dummy_rx, max_rx,
980                                        GFP_KERNEL | GFP_DMA);
981                         if (!tmp)
982                                 return -ENOMEM;
983                         ctlr->dummy_rx = tmp;
984                 }
985
986                 if (max_tx || max_rx) {
987                         list_for_each_entry(xfer, &msg->transfers,
988                                             transfer_list) {
989                                 if (!xfer->tx_buf)
990                                         xfer->tx_buf = ctlr->dummy_tx;
991                                 if (!xfer->rx_buf)
992                                         xfer->rx_buf = ctlr->dummy_rx;
993                         }
994                 }
995         }
996
997         return __spi_map_msg(ctlr, msg);
998 }
999
1000 /*
1001  * spi_transfer_one_message - Default implementation of transfer_one_message()
1002  *
1003  * This is a standard implementation of transfer_one_message() for
1004  * drivers which implement a transfer_one() operation.  It provides
1005  * standard handling of delays and chip select management.
1006  */
1007 static int spi_transfer_one_message(struct spi_controller *ctlr,
1008                                     struct spi_message *msg)
1009 {
1010         struct spi_transfer *xfer;
1011         bool keep_cs = false;
1012         int ret = 0;
1013         unsigned long long ms = 1;
1014         struct spi_statistics *statm = &ctlr->statistics;
1015         struct spi_statistics *stats = &msg->spi->statistics;
1016
1017         spi_set_cs(msg->spi, true);
1018
1019         SPI_STATISTICS_INCREMENT_FIELD(statm, messages);
1020         SPI_STATISTICS_INCREMENT_FIELD(stats, messages);
1021
1022         list_for_each_entry(xfer, &msg->transfers, transfer_list) {
1023                 trace_spi_transfer_start(msg, xfer);
1024
1025                 spi_statistics_add_transfer_stats(statm, xfer, ctlr);
1026                 spi_statistics_add_transfer_stats(stats, xfer, ctlr);
1027
1028                 if (xfer->tx_buf || xfer->rx_buf) {
1029                         reinit_completion(&ctlr->xfer_completion);
1030
1031                         ret = ctlr->transfer_one(ctlr, msg->spi, xfer);
1032                         if (ret < 0) {
1033                                 SPI_STATISTICS_INCREMENT_FIELD(statm,
1034                                                                errors);
1035                                 SPI_STATISTICS_INCREMENT_FIELD(stats,
1036                                                                errors);
1037                                 dev_err(&msg->spi->dev,
1038                                         "SPI transfer failed: %d\n", ret);
1039                                 goto out;
1040                         }
1041
1042                         if (ret > 0) {
1043                                 ret = 0;
1044                                 ms = 8LL * 1000LL * xfer->len;
1045                                 do_div(ms, xfer->speed_hz);
1046                                 ms += ms + 200; /* some tolerance */
1047
1048                                 if (ms > UINT_MAX)
1049                                         ms = UINT_MAX;
1050
1051                                 ms = wait_for_completion_timeout(&ctlr->xfer_completion,
1052                                                                  msecs_to_jiffies(ms));
1053                         }
1054
1055                         if (ms == 0) {
1056                                 SPI_STATISTICS_INCREMENT_FIELD(statm,
1057                                                                timedout);
1058                                 SPI_STATISTICS_INCREMENT_FIELD(stats,
1059                                                                timedout);
1060                                 dev_err(&msg->spi->dev,
1061                                         "SPI transfer timed out\n");
1062                                 msg->status = -ETIMEDOUT;
1063                         }
1064                 } else {
1065                         if (xfer->len)
1066                                 dev_err(&msg->spi->dev,
1067                                         "Bufferless transfer has length %u\n",
1068                                         xfer->len);
1069                 }
1070
1071                 trace_spi_transfer_stop(msg, xfer);
1072
1073                 if (msg->status != -EINPROGRESS)
1074                         goto out;
1075
1076                 if (xfer->delay_usecs) {
1077                         u16 us = xfer->delay_usecs;
1078
1079                         if (us <= 10)
1080                                 udelay(us);
1081                         else
1082                                 usleep_range(us, us + DIV_ROUND_UP(us, 10));
1083                 }
1084
1085                 if (xfer->cs_change) {
1086                         if (list_is_last(&xfer->transfer_list,
1087                                          &msg->transfers)) {
1088                                 keep_cs = true;
1089                         } else {
1090                                 spi_set_cs(msg->spi, false);
1091                                 udelay(10);
1092                                 spi_set_cs(msg->spi, true);
1093                         }
1094                 }
1095
1096                 msg->actual_length += xfer->len;
1097         }
1098
1099 out:
1100         if (ret != 0 || !keep_cs)
1101                 spi_set_cs(msg->spi, false);
1102
1103         if (msg->status == -EINPROGRESS)
1104                 msg->status = ret;
1105
1106         if (msg->status && ctlr->handle_err)
1107                 ctlr->handle_err(ctlr, msg);
1108
1109         spi_res_release(ctlr, msg);
1110
1111         spi_finalize_current_message(ctlr);
1112
1113         return ret;
1114 }
1115
1116 /**
1117  * spi_finalize_current_transfer - report completion of a transfer
1118  * @ctlr: the controller reporting completion
1119  *
1120  * Called by SPI drivers using the core transfer_one_message()
1121  * implementation to notify it that the current interrupt driven
1122  * transfer has finished and the next one may be scheduled.
1123  */
1124 void spi_finalize_current_transfer(struct spi_controller *ctlr)
1125 {
1126         complete(&ctlr->xfer_completion);
1127 }
1128 EXPORT_SYMBOL_GPL(spi_finalize_current_transfer);
1129
1130 /**
1131  * __spi_pump_messages - function which processes spi message queue
1132  * @ctlr: controller to process queue for
1133  * @in_kthread: true if we are in the context of the message pump thread
1134  *
1135  * This function checks if there is any spi message in the queue that
1136  * needs processing and if so call out to the driver to initialize hardware
1137  * and transfer each message.
1138  *
1139  * Note that it is called both from the kthread itself and also from
1140  * inside spi_sync(); the queue extraction handling at the top of the
1141  * function should deal with this safely.
1142  */
1143 static void __spi_pump_messages(struct spi_controller *ctlr, bool in_kthread)
1144 {
1145         unsigned long flags;
1146         bool was_busy = false;
1147         int ret;
1148
1149         /* Lock queue */
1150         spin_lock_irqsave(&ctlr->queue_lock, flags);
1151
1152         /* Make sure we are not already running a message */
1153         if (ctlr->cur_msg) {
1154                 spin_unlock_irqrestore(&ctlr->queue_lock, flags);
1155                 return;
1156         }
1157
1158         /* If another context is idling the device then defer */
1159         if (ctlr->idling) {
1160                 kthread_queue_work(&ctlr->kworker, &ctlr->pump_messages);
1161                 spin_unlock_irqrestore(&ctlr->queue_lock, flags);
1162                 return;
1163         }
1164
1165         /* Check if the queue is idle */
1166         if (list_empty(&ctlr->queue) || !ctlr->running) {
1167                 if (!ctlr->busy) {
1168                         spin_unlock_irqrestore(&ctlr->queue_lock, flags);
1169                         return;
1170                 }
1171
1172                 /* Only do teardown in the thread */
1173                 if (!in_kthread) {
1174                         kthread_queue_work(&ctlr->kworker,
1175                                            &ctlr->pump_messages);
1176                         spin_unlock_irqrestore(&ctlr->queue_lock, flags);
1177                         return;
1178                 }
1179
1180                 ctlr->busy = false;
1181                 ctlr->idling = true;
1182                 spin_unlock_irqrestore(&ctlr->queue_lock, flags);
1183
1184                 kfree(ctlr->dummy_rx);
1185                 ctlr->dummy_rx = NULL;
1186                 kfree(ctlr->dummy_tx);
1187                 ctlr->dummy_tx = NULL;
1188                 if (ctlr->unprepare_transfer_hardware &&
1189                     ctlr->unprepare_transfer_hardware(ctlr))
1190                         dev_err(&ctlr->dev,
1191                                 "failed to unprepare transfer hardware\n");
1192                 if (ctlr->auto_runtime_pm) {
1193                         pm_runtime_mark_last_busy(ctlr->dev.parent);
1194                         pm_runtime_put_autosuspend(ctlr->dev.parent);
1195                 }
1196                 trace_spi_controller_idle(ctlr);
1197
1198                 spin_lock_irqsave(&ctlr->queue_lock, flags);
1199                 ctlr->idling = false;
1200                 spin_unlock_irqrestore(&ctlr->queue_lock, flags);
1201                 return;
1202         }
1203
1204         /* Extract head of queue */
1205         ctlr->cur_msg =
1206                 list_first_entry(&ctlr->queue, struct spi_message, queue);
1207
1208         list_del_init(&ctlr->cur_msg->queue);
1209         if (ctlr->busy)
1210                 was_busy = true;
1211         else
1212                 ctlr->busy = true;
1213         spin_unlock_irqrestore(&ctlr->queue_lock, flags);
1214
1215         mutex_lock(&ctlr->io_mutex);
1216
1217         if (!was_busy && ctlr->auto_runtime_pm) {
1218                 ret = pm_runtime_get_sync(ctlr->dev.parent);
1219                 if (ret < 0) {
1220                         dev_err(&ctlr->dev, "Failed to power device: %d\n",
1221                                 ret);
1222                         mutex_unlock(&ctlr->io_mutex);
1223                         return;
1224                 }
1225         }
1226
1227         if (!was_busy)
1228                 trace_spi_controller_busy(ctlr);
1229
1230         if (!was_busy && ctlr->prepare_transfer_hardware) {
1231                 ret = ctlr->prepare_transfer_hardware(ctlr);
1232                 if (ret) {
1233                         dev_err(&ctlr->dev,
1234                                 "failed to prepare transfer hardware\n");
1235
1236                         if (ctlr->auto_runtime_pm)
1237                                 pm_runtime_put(ctlr->dev.parent);
1238                         mutex_unlock(&ctlr->io_mutex);
1239                         return;
1240                 }
1241         }
1242
1243         trace_spi_message_start(ctlr->cur_msg);
1244
1245         if (ctlr->prepare_message) {
1246                 ret = ctlr->prepare_message(ctlr, ctlr->cur_msg);
1247                 if (ret) {
1248                         dev_err(&ctlr->dev, "failed to prepare message: %d\n",
1249                                 ret);
1250                         ctlr->cur_msg->status = ret;
1251                         spi_finalize_current_message(ctlr);
1252                         goto out;
1253                 }
1254                 ctlr->cur_msg_prepared = true;
1255         }
1256
1257         ret = spi_map_msg(ctlr, ctlr->cur_msg);
1258         if (ret) {
1259                 ctlr->cur_msg->status = ret;
1260                 spi_finalize_current_message(ctlr);
1261                 goto out;
1262         }
1263
1264         ret = ctlr->transfer_one_message(ctlr, ctlr->cur_msg);
1265         if (ret) {
1266                 dev_err(&ctlr->dev,
1267                         "failed to transfer one message from queue\n");
1268                 goto out;
1269         }
1270
1271 out:
1272         mutex_unlock(&ctlr->io_mutex);
1273
1274         /* Prod the scheduler in case transfer_one() was busy waiting */
1275         if (!ret)
1276                 cond_resched();
1277 }
1278
1279 /**
1280  * spi_pump_messages - kthread work function which processes spi message queue
1281  * @work: pointer to kthread work struct contained in the controller struct
1282  */
1283 static void spi_pump_messages(struct kthread_work *work)
1284 {
1285         struct spi_controller *ctlr =
1286                 container_of(work, struct spi_controller, pump_messages);
1287
1288         __spi_pump_messages(ctlr, true);
1289 }
1290
1291 static int spi_init_queue(struct spi_controller *ctlr)
1292 {
1293         struct sched_param param = { .sched_priority = MAX_RT_PRIO - 1 };
1294
1295         ctlr->running = false;
1296         ctlr->busy = false;
1297
1298         kthread_init_worker(&ctlr->kworker);
1299         ctlr->kworker_task = kthread_run(kthread_worker_fn, &ctlr->kworker,
1300                                          "%s", dev_name(&ctlr->dev));
1301         if (IS_ERR(ctlr->kworker_task)) {
1302                 dev_err(&ctlr->dev, "failed to create message pump task\n");
1303                 return PTR_ERR(ctlr->kworker_task);
1304         }
1305         kthread_init_work(&ctlr->pump_messages, spi_pump_messages);
1306
1307         /*
1308          * Controller config will indicate if this controller should run the
1309          * message pump with high (realtime) priority to reduce the transfer
1310          * latency on the bus by minimising the delay between a transfer
1311          * request and the scheduling of the message pump thread. Without this
1312          * setting the message pump thread will remain at default priority.
1313          */
1314         if (ctlr->rt) {
1315                 dev_info(&ctlr->dev,
1316                         "will run message pump with realtime priority\n");
1317                 sched_setscheduler(ctlr->kworker_task, SCHED_FIFO, &param);
1318         }
1319
1320         return 0;
1321 }
1322
1323 /**
1324  * spi_get_next_queued_message() - called by driver to check for queued
1325  * messages
1326  * @ctlr: the controller to check for queued messages
1327  *
1328  * If there are more messages in the queue, the next message is returned from
1329  * this call.
1330  *
1331  * Return: the next message in the queue, else NULL if the queue is empty.
1332  */
1333 struct spi_message *spi_get_next_queued_message(struct spi_controller *ctlr)
1334 {
1335         struct spi_message *next;
1336         unsigned long flags;
1337
1338         /* get a pointer to the next message, if any */
1339         spin_lock_irqsave(&ctlr->queue_lock, flags);
1340         next = list_first_entry_or_null(&ctlr->queue, struct spi_message,
1341                                         queue);
1342         spin_unlock_irqrestore(&ctlr->queue_lock, flags);
1343
1344         return next;
1345 }
1346 EXPORT_SYMBOL_GPL(spi_get_next_queued_message);
1347
1348 /**
1349  * spi_finalize_current_message() - the current message is complete
1350  * @ctlr: the controller to return the message to
1351  *
1352  * Called by the driver to notify the core that the message in the front of the
1353  * queue is complete and can be removed from the queue.
1354  */
1355 void spi_finalize_current_message(struct spi_controller *ctlr)
1356 {
1357         struct spi_message *mesg;
1358         unsigned long flags;
1359         int ret;
1360
1361         spin_lock_irqsave(&ctlr->queue_lock, flags);
1362         mesg = ctlr->cur_msg;
1363         spin_unlock_irqrestore(&ctlr->queue_lock, flags);
1364
1365         spi_unmap_msg(ctlr, mesg);
1366
1367         if (ctlr->cur_msg_prepared && ctlr->unprepare_message) {
1368                 ret = ctlr->unprepare_message(ctlr, mesg);
1369                 if (ret) {
1370                         dev_err(&ctlr->dev, "failed to unprepare message: %d\n",
1371                                 ret);
1372                 }
1373         }
1374
1375         spin_lock_irqsave(&ctlr->queue_lock, flags);
1376         ctlr->cur_msg = NULL;
1377         ctlr->cur_msg_prepared = false;
1378         kthread_queue_work(&ctlr->kworker, &ctlr->pump_messages);
1379         spin_unlock_irqrestore(&ctlr->queue_lock, flags);
1380
1381         trace_spi_message_done(mesg);
1382
1383         mesg->state = NULL;
1384         if (mesg->complete)
1385                 mesg->complete(mesg->context);
1386 }
1387 EXPORT_SYMBOL_GPL(spi_finalize_current_message);
1388
1389 static int spi_start_queue(struct spi_controller *ctlr)
1390 {
1391         unsigned long flags;
1392
1393         spin_lock_irqsave(&ctlr->queue_lock, flags);
1394
1395         if (ctlr->running || ctlr->busy) {
1396                 spin_unlock_irqrestore(&ctlr->queue_lock, flags);
1397                 return -EBUSY;
1398         }
1399
1400         ctlr->running = true;
1401         ctlr->cur_msg = NULL;
1402         spin_unlock_irqrestore(&ctlr->queue_lock, flags);
1403
1404         kthread_queue_work(&ctlr->kworker, &ctlr->pump_messages);
1405
1406         return 0;
1407 }
1408
1409 static int spi_stop_queue(struct spi_controller *ctlr)
1410 {
1411         unsigned long flags;
1412         unsigned limit = 500;
1413         int ret = 0;
1414
1415         spin_lock_irqsave(&ctlr->queue_lock, flags);
1416
1417         /*
1418          * This is a bit lame, but is optimized for the common execution path.
1419          * A wait_queue on the ctlr->busy could be used, but then the common
1420          * execution path (pump_messages) would be required to call wake_up or
1421          * friends on every SPI message. Do this instead.
1422          */
1423         while ((!list_empty(&ctlr->queue) || ctlr->busy) && limit--) {
1424                 spin_unlock_irqrestore(&ctlr->queue_lock, flags);
1425                 usleep_range(10000, 11000);
1426                 spin_lock_irqsave(&ctlr->queue_lock, flags);
1427         }
1428
1429         if (!list_empty(&ctlr->queue) || ctlr->busy)
1430                 ret = -EBUSY;
1431         else
1432                 ctlr->running = false;
1433
1434         spin_unlock_irqrestore(&ctlr->queue_lock, flags);
1435
1436         if (ret) {
1437                 dev_warn(&ctlr->dev, "could not stop message queue\n");
1438                 return ret;
1439         }
1440         return ret;
1441 }
1442
1443 static int spi_destroy_queue(struct spi_controller *ctlr)
1444 {
1445         int ret;
1446
1447         ret = spi_stop_queue(ctlr);
1448
1449         /*
1450          * kthread_flush_worker will block until all work is done.
1451          * If the reason that stop_queue timed out is that the work will never
1452          * finish, then it does no good to call flush/stop thread, so
1453          * return anyway.
1454          */
1455         if (ret) {
1456                 dev_err(&ctlr->dev, "problem destroying queue\n");
1457                 return ret;
1458         }
1459
1460         kthread_flush_worker(&ctlr->kworker);
1461         kthread_stop(ctlr->kworker_task);
1462
1463         return 0;
1464 }
1465
1466 static int __spi_queued_transfer(struct spi_device *spi,
1467                                  struct spi_message *msg,
1468                                  bool need_pump)
1469 {
1470         struct spi_controller *ctlr = spi->controller;
1471         unsigned long flags;
1472
1473         spin_lock_irqsave(&ctlr->queue_lock, flags);
1474
1475         if (!ctlr->running) {
1476                 spin_unlock_irqrestore(&ctlr->queue_lock, flags);
1477                 return -ESHUTDOWN;
1478         }
1479         msg->actual_length = 0;
1480         msg->status = -EINPROGRESS;
1481
1482         list_add_tail(&msg->queue, &ctlr->queue);
1483         if (!ctlr->busy && need_pump)
1484                 kthread_queue_work(&ctlr->kworker, &ctlr->pump_messages);
1485
1486         spin_unlock_irqrestore(&ctlr->queue_lock, flags);
1487         return 0;
1488 }
1489
1490 /**
1491  * spi_queued_transfer - transfer function for queued transfers
1492  * @spi: spi device which is requesting transfer
1493  * @msg: spi message which is to handled is queued to driver queue
1494  *
1495  * Return: zero on success, else a negative error code.
1496  */
1497 static int spi_queued_transfer(struct spi_device *spi, struct spi_message *msg)
1498 {
1499         return __spi_queued_transfer(spi, msg, true);
1500 }
1501
1502 static int spi_controller_initialize_queue(struct spi_controller *ctlr)
1503 {
1504         int ret;
1505
1506         ctlr->transfer = spi_queued_transfer;
1507         if (!ctlr->transfer_one_message)
1508                 ctlr->transfer_one_message = spi_transfer_one_message;
1509
1510         /* Initialize and start queue */
1511         ret = spi_init_queue(ctlr);
1512         if (ret) {
1513                 dev_err(&ctlr->dev, "problem initializing queue\n");
1514                 goto err_init_queue;
1515         }
1516         ctlr->queued = true;
1517         ret = spi_start_queue(ctlr);
1518         if (ret) {
1519                 dev_err(&ctlr->dev, "problem starting queue\n");
1520                 goto err_start_queue;
1521         }
1522
1523         return 0;
1524
1525 err_start_queue:
1526         spi_destroy_queue(ctlr);
1527 err_init_queue:
1528         return ret;
1529 }
1530
1531 /*-------------------------------------------------------------------------*/
1532
1533 #if defined(CONFIG_OF)
1534 static int of_spi_parse_dt(struct spi_controller *ctlr, struct spi_device *spi,
1535                            struct device_node *nc)
1536 {
1537         u32 value;
1538         int rc;
1539
1540         /* Mode (clock phase/polarity/etc.) */
1541         if (of_property_read_bool(nc, "spi-cpha"))
1542                 spi->mode |= SPI_CPHA;
1543         if (of_property_read_bool(nc, "spi-cpol"))
1544                 spi->mode |= SPI_CPOL;
1545         if (of_property_read_bool(nc, "spi-cs-high"))
1546                 spi->mode |= SPI_CS_HIGH;
1547         if (of_property_read_bool(nc, "spi-3wire"))
1548                 spi->mode |= SPI_3WIRE;
1549         if (of_property_read_bool(nc, "spi-lsb-first"))
1550                 spi->mode |= SPI_LSB_FIRST;
1551
1552         /* Device DUAL/QUAD mode */
1553         if (!of_property_read_u32(nc, "spi-tx-bus-width", &value)) {
1554                 switch (value) {
1555                 case 1:
1556                         break;
1557                 case 2:
1558                         spi->mode |= SPI_TX_DUAL;
1559                         break;
1560                 case 4:
1561                         spi->mode |= SPI_TX_QUAD;
1562                         break;
1563                 default:
1564                         dev_warn(&ctlr->dev,
1565                                 "spi-tx-bus-width %d not supported\n",
1566                                 value);
1567                         break;
1568                 }
1569         }
1570
1571         if (!of_property_read_u32(nc, "spi-rx-bus-width", &value)) {
1572                 switch (value) {
1573                 case 1:
1574                         break;
1575                 case 2:
1576                         spi->mode |= SPI_RX_DUAL;
1577                         break;
1578                 case 4:
1579                         spi->mode |= SPI_RX_QUAD;
1580                         break;
1581                 default:
1582                         dev_warn(&ctlr->dev,
1583                                 "spi-rx-bus-width %d not supported\n",
1584                                 value);
1585                         break;
1586                 }
1587         }
1588
1589         if (spi_controller_is_slave(ctlr)) {
1590                 if (strcmp(nc->name, "slave")) {
1591                         dev_err(&ctlr->dev, "%pOF is not called 'slave'\n",
1592                                 nc);
1593                         return -EINVAL;
1594                 }
1595                 return 0;
1596         }
1597
1598         /* Device address */
1599         rc = of_property_read_u32(nc, "reg", &value);
1600         if (rc) {
1601                 dev_err(&ctlr->dev, "%pOF has no valid 'reg' property (%d)\n",
1602                         nc, rc);
1603                 return rc;
1604         }
1605         spi->chip_select = value;
1606
1607         /* Device speed */
1608         rc = of_property_read_u32(nc, "spi-max-frequency", &value);
1609         if (rc) {
1610                 dev_err(&ctlr->dev,
1611                         "%pOF has no valid 'spi-max-frequency' property (%d)\n", nc, rc);
1612                 return rc;
1613         }
1614         spi->max_speed_hz = value;
1615
1616         return 0;
1617 }
1618
1619 static struct spi_device *
1620 of_register_spi_device(struct spi_controller *ctlr, struct device_node *nc)
1621 {
1622         struct spi_device *spi;
1623         int rc;
1624
1625         /* Alloc an spi_device */
1626         spi = spi_alloc_device(ctlr);
1627         if (!spi) {
1628                 dev_err(&ctlr->dev, "spi_device alloc error for %pOF\n", nc);
1629                 rc = -ENOMEM;
1630                 goto err_out;
1631         }
1632
1633         /* Select device driver */
1634         rc = of_modalias_node(nc, spi->modalias,
1635                                 sizeof(spi->modalias));
1636         if (rc < 0) {
1637                 dev_err(&ctlr->dev, "cannot find modalias for %pOF\n", nc);
1638                 goto err_out;
1639         }
1640
1641         rc = of_spi_parse_dt(ctlr, spi, nc);
1642         if (rc)
1643                 goto err_out;
1644
1645         /* Store a pointer to the node in the device structure */
1646         of_node_get(nc);
1647         spi->dev.of_node = nc;
1648
1649         /* Register the new device */
1650         rc = spi_add_device(spi);
1651         if (rc) {
1652                 dev_err(&ctlr->dev, "spi_device register error %pOF\n", nc);
1653                 goto err_of_node_put;
1654         }
1655
1656         return spi;
1657
1658 err_of_node_put:
1659         of_node_put(nc);
1660 err_out:
1661         spi_dev_put(spi);
1662         return ERR_PTR(rc);
1663 }
1664
1665 /**
1666  * of_register_spi_devices() - Register child devices onto the SPI bus
1667  * @ctlr:       Pointer to spi_controller device
1668  *
1669  * Registers an spi_device for each child node of controller node which
1670  * represents a valid SPI slave.
1671  */
1672 static void of_register_spi_devices(struct spi_controller *ctlr)
1673 {
1674         struct spi_device *spi;
1675         struct device_node *nc;
1676
1677         if (!ctlr->dev.of_node)
1678                 return;
1679
1680         for_each_available_child_of_node(ctlr->dev.of_node, nc) {
1681                 if (of_node_test_and_set_flag(nc, OF_POPULATED))
1682                         continue;
1683                 spi = of_register_spi_device(ctlr, nc);
1684                 if (IS_ERR(spi)) {
1685                         dev_warn(&ctlr->dev,
1686                                  "Failed to create SPI device for %pOF\n", nc);
1687                         of_node_clear_flag(nc, OF_POPULATED);
1688                 }
1689         }
1690 }
1691 #else
1692 static void of_register_spi_devices(struct spi_controller *ctlr) { }
1693 #endif
1694
1695 #ifdef CONFIG_ACPI
1696 static void acpi_spi_parse_apple_properties(struct spi_device *spi)
1697 {
1698         struct acpi_device *dev = ACPI_COMPANION(&spi->dev);
1699         const union acpi_object *obj;
1700
1701         if (!x86_apple_machine)
1702                 return;
1703
1704         if (!acpi_dev_get_property(dev, "spiSclkPeriod", ACPI_TYPE_BUFFER, &obj)
1705             && obj->buffer.length >= 4)
1706                 spi->max_speed_hz  = NSEC_PER_SEC / *(u32 *)obj->buffer.pointer;
1707
1708         if (!acpi_dev_get_property(dev, "spiWordSize", ACPI_TYPE_BUFFER, &obj)
1709             && obj->buffer.length == 8)
1710                 spi->bits_per_word = *(u64 *)obj->buffer.pointer;
1711
1712         if (!acpi_dev_get_property(dev, "spiBitOrder", ACPI_TYPE_BUFFER, &obj)
1713             && obj->buffer.length == 8 && !*(u64 *)obj->buffer.pointer)
1714                 spi->mode |= SPI_LSB_FIRST;
1715
1716         if (!acpi_dev_get_property(dev, "spiSPO", ACPI_TYPE_BUFFER, &obj)
1717             && obj->buffer.length == 8 &&  *(u64 *)obj->buffer.pointer)
1718                 spi->mode |= SPI_CPOL;
1719
1720         if (!acpi_dev_get_property(dev, "spiSPH", ACPI_TYPE_BUFFER, &obj)
1721             && obj->buffer.length == 8 &&  *(u64 *)obj->buffer.pointer)
1722                 spi->mode |= SPI_CPHA;
1723 }
1724
1725 static int acpi_spi_add_resource(struct acpi_resource *ares, void *data)
1726 {
1727         struct spi_device *spi = data;
1728         struct spi_controller *ctlr = spi->controller;
1729
1730         if (ares->type == ACPI_RESOURCE_TYPE_SERIAL_BUS) {
1731                 struct acpi_resource_spi_serialbus *sb;
1732
1733                 sb = &ares->data.spi_serial_bus;
1734                 if (sb->type == ACPI_RESOURCE_SERIAL_TYPE_SPI) {
1735                         /*
1736                          * ACPI DeviceSelection numbering is handled by the
1737                          * host controller driver in Windows and can vary
1738                          * from driver to driver. In Linux we always expect
1739                          * 0 .. max - 1 so we need to ask the driver to
1740                          * translate between the two schemes.
1741                          */
1742                         if (ctlr->fw_translate_cs) {
1743                                 int cs = ctlr->fw_translate_cs(ctlr,
1744                                                 sb->device_selection);
1745                                 if (cs < 0)
1746                                         return cs;
1747                                 spi->chip_select = cs;
1748                         } else {
1749                                 spi->chip_select = sb->device_selection;
1750                         }
1751
1752                         spi->max_speed_hz = sb->connection_speed;
1753
1754                         if (sb->clock_phase == ACPI_SPI_SECOND_PHASE)
1755                                 spi->mode |= SPI_CPHA;
1756                         if (sb->clock_polarity == ACPI_SPI_START_HIGH)
1757                                 spi->mode |= SPI_CPOL;
1758                         if (sb->device_polarity == ACPI_SPI_ACTIVE_HIGH)
1759                                 spi->mode |= SPI_CS_HIGH;
1760                 }
1761         } else if (spi->irq < 0) {
1762                 struct resource r;
1763
1764                 if (acpi_dev_resource_interrupt(ares, 0, &r))
1765                         spi->irq = r.start;
1766         }
1767
1768         /* Always tell the ACPI core to skip this resource */
1769         return 1;
1770 }
1771
1772 static acpi_status acpi_register_spi_device(struct spi_controller *ctlr,
1773                                             struct acpi_device *adev)
1774 {
1775         struct list_head resource_list;
1776         struct spi_device *spi;
1777         int ret;
1778
1779         if (acpi_bus_get_status(adev) || !adev->status.present ||
1780             acpi_device_enumerated(adev))
1781                 return AE_OK;
1782
1783         spi = spi_alloc_device(ctlr);
1784         if (!spi) {
1785                 dev_err(&ctlr->dev, "failed to allocate SPI device for %s\n",
1786                         dev_name(&adev->dev));
1787                 return AE_NO_MEMORY;
1788         }
1789
1790         ACPI_COMPANION_SET(&spi->dev, adev);
1791         spi->irq = -1;
1792
1793         INIT_LIST_HEAD(&resource_list);
1794         ret = acpi_dev_get_resources(adev, &resource_list,
1795                                      acpi_spi_add_resource, spi);
1796         acpi_dev_free_resource_list(&resource_list);
1797
1798         acpi_spi_parse_apple_properties(spi);
1799
1800         if (ret < 0 || !spi->max_speed_hz) {
1801                 spi_dev_put(spi);
1802                 return AE_OK;
1803         }
1804
1805         acpi_set_modalias(adev, acpi_device_hid(adev), spi->modalias,
1806                           sizeof(spi->modalias));
1807
1808         if (spi->irq < 0)
1809                 spi->irq = acpi_dev_gpio_irq_get(adev, 0);
1810
1811         acpi_device_set_enumerated(adev);
1812
1813         adev->power.flags.ignore_parent = true;
1814         if (spi_add_device(spi)) {
1815                 adev->power.flags.ignore_parent = false;
1816                 dev_err(&ctlr->dev, "failed to add SPI device %s from ACPI\n",
1817                         dev_name(&adev->dev));
1818                 spi_dev_put(spi);
1819         }
1820
1821         return AE_OK;
1822 }
1823
1824 static acpi_status acpi_spi_add_device(acpi_handle handle, u32 level,
1825                                        void *data, void **return_value)
1826 {
1827         struct spi_controller *ctlr = data;
1828         struct acpi_device *adev;
1829
1830         if (acpi_bus_get_device(handle, &adev))
1831                 return AE_OK;
1832
1833         return acpi_register_spi_device(ctlr, adev);
1834 }
1835
1836 static void acpi_register_spi_devices(struct spi_controller *ctlr)
1837 {
1838         acpi_status status;
1839         acpi_handle handle;
1840
1841         handle = ACPI_HANDLE(ctlr->dev.parent);
1842         if (!handle)
1843                 return;
1844
1845         status = acpi_walk_namespace(ACPI_TYPE_DEVICE, handle, 1,
1846                                      acpi_spi_add_device, NULL, ctlr, NULL);
1847         if (ACPI_FAILURE(status))
1848                 dev_warn(&ctlr->dev, "failed to enumerate SPI slaves\n");
1849 }
1850 #else
1851 static inline void acpi_register_spi_devices(struct spi_controller *ctlr) {}
1852 #endif /* CONFIG_ACPI */
1853
1854 static void spi_controller_release(struct device *dev)
1855 {
1856         struct spi_controller *ctlr;
1857
1858         ctlr = container_of(dev, struct spi_controller, dev);
1859         kfree(ctlr);
1860 }
1861
1862 static struct class spi_master_class = {
1863         .name           = "spi_master",
1864         .owner          = THIS_MODULE,
1865         .dev_release    = spi_controller_release,
1866         .dev_groups     = spi_master_groups,
1867 };
1868
1869 #ifdef CONFIG_SPI_SLAVE
1870 /**
1871  * spi_slave_abort - abort the ongoing transfer request on an SPI slave
1872  *                   controller
1873  * @spi: device used for the current transfer
1874  */
1875 int spi_slave_abort(struct spi_device *spi)
1876 {
1877         struct spi_controller *ctlr = spi->controller;
1878
1879         if (spi_controller_is_slave(ctlr) && ctlr->slave_abort)
1880                 return ctlr->slave_abort(ctlr);
1881
1882         return -ENOTSUPP;
1883 }
1884 EXPORT_SYMBOL_GPL(spi_slave_abort);
1885
1886 static int match_true(struct device *dev, void *data)
1887 {
1888         return 1;
1889 }
1890
1891 static ssize_t spi_slave_show(struct device *dev,
1892                               struct device_attribute *attr, char *buf)
1893 {
1894         struct spi_controller *ctlr = container_of(dev, struct spi_controller,
1895                                                    dev);
1896         struct device *child;
1897
1898         child = device_find_child(&ctlr->dev, NULL, match_true);
1899         return sprintf(buf, "%s\n",
1900                        child ? to_spi_device(child)->modalias : NULL);
1901 }
1902
1903 static ssize_t spi_slave_store(struct device *dev,
1904                                struct device_attribute *attr, const char *buf,
1905                                size_t count)
1906 {
1907         struct spi_controller *ctlr = container_of(dev, struct spi_controller,
1908                                                    dev);
1909         struct spi_device *spi;
1910         struct device *child;
1911         char name[32];
1912         int rc;
1913
1914         rc = sscanf(buf, "%31s", name);
1915         if (rc != 1 || !name[0])
1916                 return -EINVAL;
1917
1918         child = device_find_child(&ctlr->dev, NULL, match_true);
1919         if (child) {
1920                 /* Remove registered slave */
1921                 device_unregister(child);
1922                 put_device(child);
1923         }
1924
1925         if (strcmp(name, "(null)")) {
1926                 /* Register new slave */
1927                 spi = spi_alloc_device(ctlr);
1928                 if (!spi)
1929                         return -ENOMEM;
1930
1931                 strlcpy(spi->modalias, name, sizeof(spi->modalias));
1932
1933                 rc = spi_add_device(spi);
1934                 if (rc) {
1935                         spi_dev_put(spi);
1936                         return rc;
1937                 }
1938         }
1939
1940         return count;
1941 }
1942
1943 static DEVICE_ATTR(slave, 0644, spi_slave_show, spi_slave_store);
1944
1945 static struct attribute *spi_slave_attrs[] = {
1946         &dev_attr_slave.attr,
1947         NULL,
1948 };
1949
1950 static const struct attribute_group spi_slave_group = {
1951         .attrs = spi_slave_attrs,
1952 };
1953
1954 static const struct attribute_group *spi_slave_groups[] = {
1955         &spi_controller_statistics_group,
1956         &spi_slave_group,
1957         NULL,
1958 };
1959
1960 static struct class spi_slave_class = {
1961         .name           = "spi_slave",
1962         .owner          = THIS_MODULE,
1963         .dev_release    = spi_controller_release,
1964         .dev_groups     = spi_slave_groups,
1965 };
1966 #else
1967 extern struct class spi_slave_class;    /* dummy */
1968 #endif
1969
1970 /**
1971  * __spi_alloc_controller - allocate an SPI master or slave controller
1972  * @dev: the controller, possibly using the platform_bus
1973  * @size: how much zeroed driver-private data to allocate; the pointer to this
1974  *      memory is in the driver_data field of the returned device,
1975  *      accessible with spi_controller_get_devdata().
1976  * @slave: flag indicating whether to allocate an SPI master (false) or SPI
1977  *      slave (true) controller
1978  * Context: can sleep
1979  *
1980  * This call is used only by SPI controller drivers, which are the
1981  * only ones directly touching chip registers.  It's how they allocate
1982  * an spi_controller structure, prior to calling spi_register_controller().
1983  *
1984  * This must be called from context that can sleep.
1985  *
1986  * The caller is responsible for assigning the bus number and initializing the
1987  * controller's methods before calling spi_register_controller(); and (after
1988  * errors adding the device) calling spi_controller_put() to prevent a memory
1989  * leak.
1990  *
1991  * Return: the SPI controller structure on success, else NULL.
1992  */
1993 struct spi_controller *__spi_alloc_controller(struct device *dev,
1994                                               unsigned int size, bool slave)
1995 {
1996         struct spi_controller   *ctlr;
1997
1998         if (!dev)
1999                 return NULL;
2000
2001         ctlr = kzalloc(size + sizeof(*ctlr), GFP_KERNEL);
2002         if (!ctlr)
2003                 return NULL;
2004
2005         device_initialize(&ctlr->dev);
2006         ctlr->bus_num = -1;
2007         ctlr->num_chipselect = 1;
2008         ctlr->slave = slave;
2009         if (IS_ENABLED(CONFIG_SPI_SLAVE) && slave)
2010                 ctlr->dev.class = &spi_slave_class;
2011         else
2012                 ctlr->dev.class = &spi_master_class;
2013         ctlr->dev.parent = dev;
2014         pm_suspend_ignore_children(&ctlr->dev, true);
2015         spi_controller_set_devdata(ctlr, &ctlr[1]);
2016
2017         return ctlr;
2018 }
2019 EXPORT_SYMBOL_GPL(__spi_alloc_controller);
2020
2021 #ifdef CONFIG_OF
2022 static int of_spi_register_master(struct spi_controller *ctlr)
2023 {
2024         int nb, i, *cs;
2025         struct device_node *np = ctlr->dev.of_node;
2026
2027         if (!np)
2028                 return 0;
2029
2030         nb = of_gpio_named_count(np, "cs-gpios");
2031         ctlr->num_chipselect = max_t(int, nb, ctlr->num_chipselect);
2032
2033         /* Return error only for an incorrectly formed cs-gpios property */
2034         if (nb == 0 || nb == -ENOENT)
2035                 return 0;
2036         else if (nb < 0)
2037                 return nb;
2038
2039         cs = devm_kzalloc(&ctlr->dev, sizeof(int) * ctlr->num_chipselect,
2040                           GFP_KERNEL);
2041         ctlr->cs_gpios = cs;
2042
2043         if (!ctlr->cs_gpios)
2044                 return -ENOMEM;
2045
2046         for (i = 0; i < ctlr->num_chipselect; i++)
2047                 cs[i] = -ENOENT;
2048
2049         for (i = 0; i < nb; i++)
2050                 cs[i] = of_get_named_gpio(np, "cs-gpios", i);
2051
2052         return 0;
2053 }
2054 #else
2055 static int of_spi_register_master(struct spi_controller *ctlr)
2056 {
2057         return 0;
2058 }
2059 #endif
2060
2061 /**
2062  * spi_register_controller - register SPI master or slave controller
2063  * @ctlr: initialized master, originally from spi_alloc_master() or
2064  *      spi_alloc_slave()
2065  * Context: can sleep
2066  *
2067  * SPI controllers connect to their drivers using some non-SPI bus,
2068  * such as the platform bus.  The final stage of probe() in that code
2069  * includes calling spi_register_controller() to hook up to this SPI bus glue.
2070  *
2071  * SPI controllers use board specific (often SOC specific) bus numbers,
2072  * and board-specific addressing for SPI devices combines those numbers
2073  * with chip select numbers.  Since SPI does not directly support dynamic
2074  * device identification, boards need configuration tables telling which
2075  * chip is at which address.
2076  *
2077  * This must be called from context that can sleep.  It returns zero on
2078  * success, else a negative error code (dropping the controller's refcount).
2079  * After a successful return, the caller is responsible for calling
2080  * spi_unregister_controller().
2081  *
2082  * Return: zero on success, else a negative error code.
2083  */
2084 int spi_register_controller(struct spi_controller *ctlr)
2085 {
2086         struct device           *dev = ctlr->dev.parent;
2087         struct boardinfo        *bi;
2088         int                     status = -ENODEV;
2089         int                     id;
2090
2091         if (!dev)
2092                 return -ENODEV;
2093
2094         if (!spi_controller_is_slave(ctlr)) {
2095                 status = of_spi_register_master(ctlr);
2096                 if (status)
2097                         return status;
2098         }
2099
2100         /* even if it's just one always-selected device, there must
2101          * be at least one chipselect
2102          */
2103         if (ctlr->num_chipselect == 0)
2104                 return -EINVAL;
2105         /* allocate dynamic bus number using Linux idr */
2106         if ((ctlr->bus_num < 0) && ctlr->dev.of_node) {
2107                 id = of_alias_get_id(ctlr->dev.of_node, "spi");
2108                 if (id >= 0) {
2109                         ctlr->bus_num = id;
2110                         mutex_lock(&board_lock);
2111                         id = idr_alloc(&spi_master_idr, ctlr, ctlr->bus_num,
2112                                        ctlr->bus_num + 1, GFP_KERNEL);
2113                         mutex_unlock(&board_lock);
2114                         if (WARN(id < 0, "couldn't get idr"))
2115                                 return id == -ENOSPC ? -EBUSY : id;
2116                 }
2117         }
2118         if (ctlr->bus_num < 0) {
2119                 mutex_lock(&board_lock);
2120                 id = idr_alloc(&spi_master_idr, ctlr, SPI_DYN_FIRST_BUS_NUM, 0,
2121                                GFP_KERNEL);
2122                 mutex_unlock(&board_lock);
2123                 if (WARN(id < 0, "couldn't get idr"))
2124                         return id;
2125                 ctlr->bus_num = id;
2126         }
2127         INIT_LIST_HEAD(&ctlr->queue);
2128         spin_lock_init(&ctlr->queue_lock);
2129         spin_lock_init(&ctlr->bus_lock_spinlock);
2130         mutex_init(&ctlr->bus_lock_mutex);
2131         mutex_init(&ctlr->io_mutex);
2132         ctlr->bus_lock_flag = 0;
2133         init_completion(&ctlr->xfer_completion);
2134         if (!ctlr->max_dma_len)
2135                 ctlr->max_dma_len = INT_MAX;
2136
2137         /* register the device, then userspace will see it.
2138          * registration fails if the bus ID is in use.
2139          */
2140         dev_set_name(&ctlr->dev, "spi%u", ctlr->bus_num);
2141         status = device_add(&ctlr->dev);
2142         if (status < 0) {
2143                 /* free bus id */
2144                 mutex_lock(&board_lock);
2145                 idr_remove(&spi_master_idr, ctlr->bus_num);
2146                 mutex_unlock(&board_lock);
2147                 goto done;
2148         }
2149         dev_dbg(dev, "registered %s %s\n",
2150                         spi_controller_is_slave(ctlr) ? "slave" : "master",
2151                         dev_name(&ctlr->dev));
2152
2153         /* If we're using a queued driver, start the queue */
2154         if (ctlr->transfer)
2155                 dev_info(dev, "controller is unqueued, this is deprecated\n");
2156         else {
2157                 status = spi_controller_initialize_queue(ctlr);
2158                 if (status) {
2159                         device_del(&ctlr->dev);
2160                         /* free bus id */
2161                         mutex_lock(&board_lock);
2162                         idr_remove(&spi_master_idr, ctlr->bus_num);
2163                         mutex_unlock(&board_lock);
2164                         goto done;
2165                 }
2166         }
2167         /* add statistics */
2168         spin_lock_init(&ctlr->statistics.lock);
2169
2170         mutex_lock(&board_lock);
2171         list_add_tail(&ctlr->list, &spi_controller_list);
2172         list_for_each_entry(bi, &board_list, list)
2173                 spi_match_controller_to_boardinfo(ctlr, &bi->board_info);
2174         mutex_unlock(&board_lock);
2175
2176         /* Register devices from the device tree and ACPI */
2177         of_register_spi_devices(ctlr);
2178         acpi_register_spi_devices(ctlr);
2179 done:
2180         return status;
2181 }
2182 EXPORT_SYMBOL_GPL(spi_register_controller);
2183
2184 static void devm_spi_unregister(struct device *dev, void *res)
2185 {
2186         spi_unregister_controller(*(struct spi_controller **)res);
2187 }
2188
2189 /**
2190  * devm_spi_register_controller - register managed SPI master or slave
2191  *      controller
2192  * @dev:    device managing SPI controller
2193  * @ctlr: initialized controller, originally from spi_alloc_master() or
2194  *      spi_alloc_slave()
2195  * Context: can sleep
2196  *
2197  * Register a SPI device as with spi_register_controller() which will
2198  * automatically be unregister
2199  *
2200  * Return: zero on success, else a negative error code.
2201  */
2202 int devm_spi_register_controller(struct device *dev,
2203                                  struct spi_controller *ctlr)
2204 {
2205         struct spi_controller **ptr;
2206         int ret;
2207
2208         ptr = devres_alloc(devm_spi_unregister, sizeof(*ptr), GFP_KERNEL);
2209         if (!ptr)
2210                 return -ENOMEM;
2211
2212         ret = spi_register_controller(ctlr);
2213         if (!ret) {
2214                 *ptr = ctlr;
2215                 devres_add(dev, ptr);
2216         } else {
2217                 devres_free(ptr);
2218         }
2219
2220         return ret;
2221 }
2222 EXPORT_SYMBOL_GPL(devm_spi_register_controller);
2223
2224 static int __unregister(struct device *dev, void *null)
2225 {
2226         spi_unregister_device(to_spi_device(dev));
2227         return 0;
2228 }
2229
2230 /**
2231  * spi_unregister_controller - unregister SPI master or slave controller
2232  * @ctlr: the controller being unregistered
2233  * Context: can sleep
2234  *
2235  * This call is used only by SPI controller drivers, which are the
2236  * only ones directly touching chip registers.
2237  *
2238  * This must be called from context that can sleep.
2239  */
2240 void spi_unregister_controller(struct spi_controller *ctlr)
2241 {
2242         struct spi_controller *found;
2243         int dummy;
2244
2245         /* First make sure that this controller was ever added */
2246         mutex_lock(&board_lock);
2247         found = idr_find(&spi_master_idr, ctlr->bus_num);
2248         mutex_unlock(&board_lock);
2249         if (found != ctlr) {
2250                 dev_dbg(&ctlr->dev,
2251                         "attempting to delete unregistered controller [%s]\n",
2252                         dev_name(&ctlr->dev));
2253                 return;
2254         }
2255         if (ctlr->queued) {
2256                 if (spi_destroy_queue(ctlr))
2257                         dev_err(&ctlr->dev, "queue remove failed\n");
2258         }
2259         mutex_lock(&board_lock);
2260         list_del(&ctlr->list);
2261         mutex_unlock(&board_lock);
2262
2263         dummy = device_for_each_child(&ctlr->dev, NULL, __unregister);
2264         device_unregister(&ctlr->dev);
2265         /* free bus id */
2266         mutex_lock(&board_lock);
2267         idr_remove(&spi_master_idr, ctlr->bus_num);
2268         mutex_unlock(&board_lock);
2269 }
2270 EXPORT_SYMBOL_GPL(spi_unregister_controller);
2271
2272 int spi_controller_suspend(struct spi_controller *ctlr)
2273 {
2274         int ret;
2275
2276         /* Basically no-ops for non-queued controllers */
2277         if (!ctlr->queued)
2278                 return 0;
2279
2280         ret = spi_stop_queue(ctlr);
2281         if (ret)
2282                 dev_err(&ctlr->dev, "queue stop failed\n");
2283
2284         return ret;
2285 }
2286 EXPORT_SYMBOL_GPL(spi_controller_suspend);
2287
2288 int spi_controller_resume(struct spi_controller *ctlr)
2289 {
2290         int ret;
2291
2292         if (!ctlr->queued)
2293                 return 0;
2294
2295         ret = spi_start_queue(ctlr);
2296         if (ret)
2297                 dev_err(&ctlr->dev, "queue restart failed\n");
2298
2299         return ret;
2300 }
2301 EXPORT_SYMBOL_GPL(spi_controller_resume);
2302
2303 static int __spi_controller_match(struct device *dev, const void *data)
2304 {
2305         struct spi_controller *ctlr;
2306         const u16 *bus_num = data;
2307
2308         ctlr = container_of(dev, struct spi_controller, dev);
2309         return ctlr->bus_num == *bus_num;
2310 }
2311
2312 /**
2313  * spi_busnum_to_master - look up master associated with bus_num
2314  * @bus_num: the master's bus number
2315  * Context: can sleep
2316  *
2317  * This call may be used with devices that are registered after
2318  * arch init time.  It returns a refcounted pointer to the relevant
2319  * spi_controller (which the caller must release), or NULL if there is
2320  * no such master registered.
2321  *
2322  * Return: the SPI master structure on success, else NULL.
2323  */
2324 struct spi_controller *spi_busnum_to_master(u16 bus_num)
2325 {
2326         struct device           *dev;
2327         struct spi_controller   *ctlr = NULL;
2328
2329         dev = class_find_device(&spi_master_class, NULL, &bus_num,
2330                                 __spi_controller_match);
2331         if (dev)
2332                 ctlr = container_of(dev, struct spi_controller, dev);
2333         /* reference got in class_find_device */
2334         return ctlr;
2335 }
2336 EXPORT_SYMBOL_GPL(spi_busnum_to_master);
2337
2338 /*-------------------------------------------------------------------------*/
2339
2340 /* Core methods for SPI resource management */
2341
2342 /**
2343  * spi_res_alloc - allocate a spi resource that is life-cycle managed
2344  *                 during the processing of a spi_message while using
2345  *                 spi_transfer_one
2346  * @spi:     the spi device for which we allocate memory
2347  * @release: the release code to execute for this resource
2348  * @size:    size to alloc and return
2349  * @gfp:     GFP allocation flags
2350  *
2351  * Return: the pointer to the allocated data
2352  *
2353  * This may get enhanced in the future to allocate from a memory pool
2354  * of the @spi_device or @spi_controller to avoid repeated allocations.
2355  */
2356 void *spi_res_alloc(struct spi_device *spi,
2357                     spi_res_release_t release,
2358                     size_t size, gfp_t gfp)
2359 {
2360         struct spi_res *sres;
2361
2362         sres = kzalloc(sizeof(*sres) + size, gfp);
2363         if (!sres)
2364                 return NULL;
2365
2366         INIT_LIST_HEAD(&sres->entry);
2367         sres->release = release;
2368
2369         return sres->data;
2370 }
2371 EXPORT_SYMBOL_GPL(spi_res_alloc);
2372
2373 /**
2374  * spi_res_free - free an spi resource
2375  * @res: pointer to the custom data of a resource
2376  *
2377  */
2378 void spi_res_free(void *res)
2379 {
2380         struct spi_res *sres = container_of(res, struct spi_res, data);
2381
2382         if (!res)
2383                 return;
2384
2385         WARN_ON(!list_empty(&sres->entry));
2386         kfree(sres);
2387 }
2388 EXPORT_SYMBOL_GPL(spi_res_free);
2389
2390 /**
2391  * spi_res_add - add a spi_res to the spi_message
2392  * @message: the spi message
2393  * @res:     the spi_resource
2394  */
2395 void spi_res_add(struct spi_message *message, void *res)
2396 {
2397         struct spi_res *sres = container_of(res, struct spi_res, data);
2398
2399         WARN_ON(!list_empty(&sres->entry));
2400         list_add_tail(&sres->entry, &message->resources);
2401 }
2402 EXPORT_SYMBOL_GPL(spi_res_add);
2403
2404 /**
2405  * spi_res_release - release all spi resources for this message
2406  * @ctlr:  the @spi_controller
2407  * @message: the @spi_message
2408  */
2409 void spi_res_release(struct spi_controller *ctlr, struct spi_message *message)
2410 {
2411         struct spi_res *res;
2412
2413         while (!list_empty(&message->resources)) {
2414                 res = list_last_entry(&message->resources,
2415                                       struct spi_res, entry);
2416
2417                 if (res->release)
2418                         res->release(ctlr, message, res->data);
2419
2420                 list_del(&res->entry);
2421
2422                 kfree(res);
2423         }
2424 }
2425 EXPORT_SYMBOL_GPL(spi_res_release);
2426
2427 /*-------------------------------------------------------------------------*/
2428
2429 /* Core methods for spi_message alterations */
2430
2431 static void __spi_replace_transfers_release(struct spi_controller *ctlr,
2432                                             struct spi_message *msg,
2433                                             void *res)
2434 {
2435         struct spi_replaced_transfers *rxfer = res;
2436         size_t i;
2437
2438         /* call extra callback if requested */
2439         if (rxfer->release)
2440                 rxfer->release(ctlr, msg, res);
2441
2442         /* insert replaced transfers back into the message */
2443         list_splice(&rxfer->replaced_transfers, rxfer->replaced_after);
2444
2445         /* remove the formerly inserted entries */
2446         for (i = 0; i < rxfer->inserted; i++)
2447                 list_del(&rxfer->inserted_transfers[i].transfer_list);
2448 }
2449
2450 /**
2451  * spi_replace_transfers - replace transfers with several transfers
2452  *                         and register change with spi_message.resources
2453  * @msg:           the spi_message we work upon
2454  * @xfer_first:    the first spi_transfer we want to replace
2455  * @remove:        number of transfers to remove
2456  * @insert:        the number of transfers we want to insert instead
2457  * @release:       extra release code necessary in some circumstances
2458  * @extradatasize: extra data to allocate (with alignment guarantees
2459  *                 of struct @spi_transfer)
2460  * @gfp:           gfp flags
2461  *
2462  * Returns: pointer to @spi_replaced_transfers,
2463  *          PTR_ERR(...) in case of errors.
2464  */
2465 struct spi_replaced_transfers *spi_replace_transfers(
2466         struct spi_message *msg,
2467         struct spi_transfer *xfer_first,
2468         size_t remove,
2469         size_t insert,
2470         spi_replaced_release_t release,
2471         size_t extradatasize,
2472         gfp_t gfp)
2473 {
2474         struct spi_replaced_transfers *rxfer;
2475         struct spi_transfer *xfer;
2476         size_t i;
2477
2478         /* allocate the structure using spi_res */
2479         rxfer = spi_res_alloc(msg->spi, __spi_replace_transfers_release,
2480                               insert * sizeof(struct spi_transfer)
2481                               + sizeof(struct spi_replaced_transfers)
2482                               + extradatasize,
2483                               gfp);
2484         if (!rxfer)
2485                 return ERR_PTR(-ENOMEM);
2486
2487         /* the release code to invoke before running the generic release */
2488         rxfer->release = release;
2489
2490         /* assign extradata */
2491         if (extradatasize)
2492                 rxfer->extradata =
2493                         &rxfer->inserted_transfers[insert];
2494
2495         /* init the replaced_transfers list */
2496         INIT_LIST_HEAD(&rxfer->replaced_transfers);
2497
2498         /* assign the list_entry after which we should reinsert
2499          * the @replaced_transfers - it may be spi_message.messages!
2500          */
2501         rxfer->replaced_after = xfer_first->transfer_list.prev;
2502
2503         /* remove the requested number of transfers */
2504         for (i = 0; i < remove; i++) {
2505                 /* if the entry after replaced_after it is msg->transfers
2506                  * then we have been requested to remove more transfers
2507                  * than are in the list
2508                  */
2509                 if (rxfer->replaced_after->next == &msg->transfers) {
2510                         dev_err(&msg->spi->dev,
2511                                 "requested to remove more spi_transfers than are available\n");
2512                         /* insert replaced transfers back into the message */
2513                         list_splice(&rxfer->replaced_transfers,
2514                                     rxfer->replaced_after);
2515
2516                         /* free the spi_replace_transfer structure */
2517                         spi_res_free(rxfer);
2518
2519                         /* and return with an error */
2520                         return ERR_PTR(-EINVAL);
2521                 }
2522
2523                 /* remove the entry after replaced_after from list of
2524                  * transfers and add it to list of replaced_transfers
2525                  */
2526                 list_move_tail(rxfer->replaced_after->next,
2527                                &rxfer->replaced_transfers);
2528         }
2529
2530         /* create copy of the given xfer with identical settings
2531          * based on the first transfer to get removed
2532          */
2533         for (i = 0; i < insert; i++) {
2534                 /* we need to run in reverse order */
2535                 xfer = &rxfer->inserted_transfers[insert - 1 - i];
2536
2537                 /* copy all spi_transfer data */
2538                 memcpy(xfer, xfer_first, sizeof(*xfer));
2539
2540                 /* add to list */
2541                 list_add(&xfer->transfer_list, rxfer->replaced_after);
2542
2543                 /* clear cs_change and delay_usecs for all but the last */
2544                 if (i) {
2545                         xfer->cs_change = false;
2546                         xfer->delay_usecs = 0;
2547                 }
2548         }
2549
2550         /* set up inserted */
2551         rxfer->inserted = insert;
2552
2553         /* and register it with spi_res/spi_message */
2554         spi_res_add(msg, rxfer);
2555
2556         return rxfer;
2557 }
2558 EXPORT_SYMBOL_GPL(spi_replace_transfers);
2559
2560 static int __spi_split_transfer_maxsize(struct spi_controller *ctlr,
2561                                         struct spi_message *msg,
2562                                         struct spi_transfer **xferp,
2563                                         size_t maxsize,
2564                                         gfp_t gfp)
2565 {
2566         struct spi_transfer *xfer = *xferp, *xfers;
2567         struct spi_replaced_transfers *srt;
2568         size_t offset;
2569         size_t count, i;
2570
2571         /* warn once about this fact that we are splitting a transfer */
2572         dev_warn_once(&msg->spi->dev,
2573                       "spi_transfer of length %i exceed max length of %zu - needed to split transfers\n",
2574                       xfer->len, maxsize);
2575
2576         /* calculate how many we have to replace */
2577         count = DIV_ROUND_UP(xfer->len, maxsize);
2578
2579         /* create replacement */
2580         srt = spi_replace_transfers(msg, xfer, 1, count, NULL, 0, gfp);
2581         if (IS_ERR(srt))
2582                 return PTR_ERR(srt);
2583         xfers = srt->inserted_transfers;
2584
2585         /* now handle each of those newly inserted spi_transfers
2586          * note that the replacements spi_transfers all are preset
2587          * to the same values as *xferp, so tx_buf, rx_buf and len
2588          * are all identical (as well as most others)
2589          * so we just have to fix up len and the pointers.
2590          *
2591          * this also includes support for the depreciated
2592          * spi_message.is_dma_mapped interface
2593          */
2594
2595         /* the first transfer just needs the length modified, so we
2596          * run it outside the loop
2597          */
2598         xfers[0].len = min_t(size_t, maxsize, xfer[0].len);
2599
2600         /* all the others need rx_buf/tx_buf also set */
2601         for (i = 1, offset = maxsize; i < count; offset += maxsize, i++) {
2602                 /* update rx_buf, tx_buf and dma */
2603                 if (xfers[i].rx_buf)
2604                         xfers[i].rx_buf += offset;
2605                 if (xfers[i].rx_dma)
2606                         xfers[i].rx_dma += offset;
2607                 if (xfers[i].tx_buf)
2608                         xfers[i].tx_buf += offset;
2609                 if (xfers[i].tx_dma)
2610                         xfers[i].tx_dma += offset;
2611
2612                 /* update length */
2613                 xfers[i].len = min(maxsize, xfers[i].len - offset);
2614         }
2615
2616         /* we set up xferp to the last entry we have inserted,
2617          * so that we skip those already split transfers
2618          */
2619         *xferp = &xfers[count - 1];
2620
2621         /* increment statistics counters */
2622         SPI_STATISTICS_INCREMENT_FIELD(&ctlr->statistics,
2623                                        transfers_split_maxsize);
2624         SPI_STATISTICS_INCREMENT_FIELD(&msg->spi->statistics,
2625                                        transfers_split_maxsize);
2626
2627         return 0;
2628 }
2629
2630 /**
2631  * spi_split_tranfers_maxsize - split spi transfers into multiple transfers
2632  *                              when an individual transfer exceeds a
2633  *                              certain size
2634  * @ctlr:    the @spi_controller for this transfer
2635  * @msg:   the @spi_message to transform
2636  * @maxsize:  the maximum when to apply this
2637  * @gfp: GFP allocation flags
2638  *
2639  * Return: status of transformation
2640  */
2641 int spi_split_transfers_maxsize(struct spi_controller *ctlr,
2642                                 struct spi_message *msg,
2643                                 size_t maxsize,
2644                                 gfp_t gfp)
2645 {
2646         struct spi_transfer *xfer;
2647         int ret;
2648
2649         /* iterate over the transfer_list,
2650          * but note that xfer is advanced to the last transfer inserted
2651          * to avoid checking sizes again unnecessarily (also xfer does
2652          * potentiall belong to a different list by the time the
2653          * replacement has happened
2654          */
2655         list_for_each_entry(xfer, &msg->transfers, transfer_list) {
2656                 if (xfer->len > maxsize) {
2657                         ret = __spi_split_transfer_maxsize(ctlr, msg, &xfer,
2658                                                            maxsize, gfp);
2659                         if (ret)
2660                                 return ret;
2661                 }
2662         }
2663
2664         return 0;
2665 }
2666 EXPORT_SYMBOL_GPL(spi_split_transfers_maxsize);
2667
2668 /*-------------------------------------------------------------------------*/
2669
2670 /* Core methods for SPI controller protocol drivers.  Some of the
2671  * other core methods are currently defined as inline functions.
2672  */
2673
2674 static int __spi_validate_bits_per_word(struct spi_controller *ctlr,
2675                                         u8 bits_per_word)
2676 {
2677         if (ctlr->bits_per_word_mask) {
2678                 /* Only 32 bits fit in the mask */
2679                 if (bits_per_word > 32)
2680                         return -EINVAL;
2681                 if (!(ctlr->bits_per_word_mask & SPI_BPW_MASK(bits_per_word)))
2682                         return -EINVAL;
2683         }
2684
2685         return 0;
2686 }
2687
2688 /**
2689  * spi_setup - setup SPI mode and clock rate
2690  * @spi: the device whose settings are being modified
2691  * Context: can sleep, and no requests are queued to the device
2692  *
2693  * SPI protocol drivers may need to update the transfer mode if the
2694  * device doesn't work with its default.  They may likewise need
2695  * to update clock rates or word sizes from initial values.  This function
2696  * changes those settings, and must be called from a context that can sleep.
2697  * Except for SPI_CS_HIGH, which takes effect immediately, the changes take
2698  * effect the next time the device is selected and data is transferred to
2699  * or from it.  When this function returns, the spi device is deselected.
2700  *
2701  * Note that this call will fail if the protocol driver specifies an option
2702  * that the underlying controller or its driver does not support.  For
2703  * example, not all hardware supports wire transfers using nine bit words,
2704  * LSB-first wire encoding, or active-high chipselects.
2705  *
2706  * Return: zero on success, else a negative error code.
2707  */
2708 int spi_setup(struct spi_device *spi)
2709 {
2710         unsigned        bad_bits, ugly_bits;
2711         int             status;
2712
2713         /* check mode to prevent that DUAL and QUAD set at the same time
2714          */
2715         if (((spi->mode & SPI_TX_DUAL) && (spi->mode & SPI_TX_QUAD)) ||
2716                 ((spi->mode & SPI_RX_DUAL) && (spi->mode & SPI_RX_QUAD))) {
2717                 dev_err(&spi->dev,
2718                 "setup: can not select dual and quad at the same time\n");
2719                 return -EINVAL;
2720         }
2721         /* if it is SPI_3WIRE mode, DUAL and QUAD should be forbidden
2722          */
2723         if ((spi->mode & SPI_3WIRE) && (spi->mode &
2724                 (SPI_TX_DUAL | SPI_TX_QUAD | SPI_RX_DUAL | SPI_RX_QUAD)))
2725                 return -EINVAL;
2726         /* help drivers fail *cleanly* when they need options
2727          * that aren't supported with their current controller
2728          */
2729         bad_bits = spi->mode & ~spi->controller->mode_bits;
2730         ugly_bits = bad_bits &
2731                     (SPI_TX_DUAL | SPI_TX_QUAD | SPI_RX_DUAL | SPI_RX_QUAD);
2732         if (ugly_bits) {
2733                 dev_warn(&spi->dev,
2734                          "setup: ignoring unsupported mode bits %x\n",
2735                          ugly_bits);
2736                 spi->mode &= ~ugly_bits;
2737                 bad_bits &= ~ugly_bits;
2738         }
2739         if (bad_bits) {
2740                 dev_err(&spi->dev, "setup: unsupported mode bits %x\n",
2741                         bad_bits);
2742                 return -EINVAL;
2743         }
2744
2745         if (!spi->bits_per_word)
2746                 spi->bits_per_word = 8;
2747
2748         status = __spi_validate_bits_per_word(spi->controller,
2749                                               spi->bits_per_word);
2750         if (status)
2751                 return status;
2752
2753         if (!spi->max_speed_hz)
2754                 spi->max_speed_hz = spi->controller->max_speed_hz;
2755
2756         if (spi->controller->setup)
2757                 status = spi->controller->setup(spi);
2758
2759         spi_set_cs(spi, false);
2760
2761         dev_dbg(&spi->dev, "setup mode %d, %s%s%s%s%u bits/w, %u Hz max --> %d\n",
2762                         (int) (spi->mode & (SPI_CPOL | SPI_CPHA)),
2763                         (spi->mode & SPI_CS_HIGH) ? "cs_high, " : "",
2764                         (spi->mode & SPI_LSB_FIRST) ? "lsb, " : "",
2765                         (spi->mode & SPI_3WIRE) ? "3wire, " : "",
2766                         (spi->mode & SPI_LOOP) ? "loopback, " : "",
2767                         spi->bits_per_word, spi->max_speed_hz,
2768                         status);
2769
2770         return status;
2771 }
2772 EXPORT_SYMBOL_GPL(spi_setup);
2773
2774 static int __spi_validate(struct spi_device *spi, struct spi_message *message)
2775 {
2776         struct spi_controller *ctlr = spi->controller;
2777         struct spi_transfer *xfer;
2778         int w_size;
2779
2780         if (list_empty(&message->transfers))
2781                 return -EINVAL;
2782
2783         /* Half-duplex links include original MicroWire, and ones with
2784          * only one data pin like SPI_3WIRE (switches direction) or where
2785          * either MOSI or MISO is missing.  They can also be caused by
2786          * software limitations.
2787          */
2788         if ((ctlr->flags & SPI_CONTROLLER_HALF_DUPLEX) ||
2789             (spi->mode & SPI_3WIRE)) {
2790                 unsigned flags = ctlr->flags;
2791
2792                 list_for_each_entry(xfer, &message->transfers, transfer_list) {
2793                         if (xfer->rx_buf && xfer->tx_buf)
2794                                 return -EINVAL;
2795                         if ((flags & SPI_CONTROLLER_NO_TX) && xfer->tx_buf)
2796                                 return -EINVAL;
2797                         if ((flags & SPI_CONTROLLER_NO_RX) && xfer->rx_buf)
2798                                 return -EINVAL;
2799                 }
2800         }
2801
2802         /**
2803          * Set transfer bits_per_word and max speed as spi device default if
2804          * it is not set for this transfer.
2805          * Set transfer tx_nbits and rx_nbits as single transfer default
2806          * (SPI_NBITS_SINGLE) if it is not set for this transfer.
2807          */
2808         message->frame_length = 0;
2809         list_for_each_entry(xfer, &message->transfers, transfer_list) {
2810                 message->frame_length += xfer->len;
2811                 if (!xfer->bits_per_word)
2812                         xfer->bits_per_word = spi->bits_per_word;
2813
2814                 if (!xfer->speed_hz)
2815                         xfer->speed_hz = spi->max_speed_hz;
2816                 if (!xfer->speed_hz)
2817                         xfer->speed_hz = ctlr->max_speed_hz;
2818
2819                 if (ctlr->max_speed_hz && xfer->speed_hz > ctlr->max_speed_hz)
2820                         xfer->speed_hz = ctlr->max_speed_hz;
2821
2822                 if (__spi_validate_bits_per_word(ctlr, xfer->bits_per_word))
2823                         return -EINVAL;
2824
2825                 /*
2826                  * SPI transfer length should be multiple of SPI word size
2827                  * where SPI word size should be power-of-two multiple
2828                  */
2829                 if (xfer->bits_per_word <= 8)
2830                         w_size = 1;
2831                 else if (xfer->bits_per_word <= 16)
2832                         w_size = 2;
2833                 else
2834                         w_size = 4;
2835
2836                 /* No partial transfers accepted */
2837                 if (xfer->len % w_size)
2838                         return -EINVAL;
2839
2840                 if (xfer->speed_hz && ctlr->min_speed_hz &&
2841                     xfer->speed_hz < ctlr->min_speed_hz)
2842                         return -EINVAL;
2843
2844                 if (xfer->tx_buf && !xfer->tx_nbits)
2845                         xfer->tx_nbits = SPI_NBITS_SINGLE;
2846                 if (xfer->rx_buf && !xfer->rx_nbits)
2847                         xfer->rx_nbits = SPI_NBITS_SINGLE;
2848                 /* check transfer tx/rx_nbits:
2849                  * 1. check the value matches one of single, dual and quad
2850                  * 2. check tx/rx_nbits match the mode in spi_device
2851                  */
2852                 if (xfer->tx_buf) {
2853                         if (xfer->tx_nbits != SPI_NBITS_SINGLE &&
2854                                 xfer->tx_nbits != SPI_NBITS_DUAL &&
2855                                 xfer->tx_nbits != SPI_NBITS_QUAD)
2856                                 return -EINVAL;
2857                         if ((xfer->tx_nbits == SPI_NBITS_DUAL) &&
2858                                 !(spi->mode & (SPI_TX_DUAL | SPI_TX_QUAD)))
2859                                 return -EINVAL;
2860                         if ((xfer->tx_nbits == SPI_NBITS_QUAD) &&
2861                                 !(spi->mode & SPI_TX_QUAD))
2862                                 return -EINVAL;
2863                 }
2864                 /* check transfer rx_nbits */
2865                 if (xfer->rx_buf) {
2866                         if (xfer->rx_nbits != SPI_NBITS_SINGLE &&
2867                                 xfer->rx_nbits != SPI_NBITS_DUAL &&
2868                                 xfer->rx_nbits != SPI_NBITS_QUAD)
2869                                 return -EINVAL;
2870                         if ((xfer->rx_nbits == SPI_NBITS_DUAL) &&
2871                                 !(spi->mode & (SPI_RX_DUAL | SPI_RX_QUAD)))
2872                                 return -EINVAL;
2873                         if ((xfer->rx_nbits == SPI_NBITS_QUAD) &&
2874                                 !(spi->mode & SPI_RX_QUAD))
2875                                 return -EINVAL;
2876                 }
2877         }
2878
2879         message->status = -EINPROGRESS;
2880
2881         return 0;
2882 }
2883
2884 static int __spi_async(struct spi_device *spi, struct spi_message *message)
2885 {
2886         struct spi_controller *ctlr = spi->controller;
2887
2888         message->spi = spi;
2889
2890         SPI_STATISTICS_INCREMENT_FIELD(&ctlr->statistics, spi_async);
2891         SPI_STATISTICS_INCREMENT_FIELD(&spi->statistics, spi_async);
2892
2893         trace_spi_message_submit(message);
2894
2895         return ctlr->transfer(spi, message);
2896 }
2897
2898 /**
2899  * spi_async - asynchronous SPI transfer
2900  * @spi: device with which data will be exchanged
2901  * @message: describes the data transfers, including completion callback
2902  * Context: any (irqs may be blocked, etc)
2903  *
2904  * This call may be used in_irq and other contexts which can't sleep,
2905  * as well as from task contexts which can sleep.
2906  *
2907  * The completion callback is invoked in a context which can't sleep.
2908  * Before that invocation, the value of message->status is undefined.
2909  * When the callback is issued, message->status holds either zero (to
2910  * indicate complete success) or a negative error code.  After that
2911  * callback returns, the driver which issued the transfer request may
2912  * deallocate the associated memory; it's no longer in use by any SPI
2913  * core or controller driver code.
2914  *
2915  * Note that although all messages to a spi_device are handled in
2916  * FIFO order, messages may go to different devices in other orders.
2917  * Some device might be higher priority, or have various "hard" access
2918  * time requirements, for example.
2919  *
2920  * On detection of any fault during the transfer, processing of
2921  * the entire message is aborted, and the device is deselected.
2922  * Until returning from the associated message completion callback,
2923  * no other spi_message queued to that device will be processed.
2924  * (This rule applies equally to all the synchronous transfer calls,
2925  * which are wrappers around this core asynchronous primitive.)
2926  *
2927  * Return: zero on success, else a negative error code.
2928  */
2929 int spi_async(struct spi_device *spi, struct spi_message *message)
2930 {
2931         struct spi_controller *ctlr = spi->controller;
2932         int ret;
2933         unsigned long flags;
2934
2935         ret = __spi_validate(spi, message);
2936         if (ret != 0)
2937                 return ret;
2938
2939         spin_lock_irqsave(&ctlr->bus_lock_spinlock, flags);
2940
2941         if (ctlr->bus_lock_flag)
2942                 ret = -EBUSY;
2943         else
2944                 ret = __spi_async(spi, message);
2945
2946         spin_unlock_irqrestore(&ctlr->bus_lock_spinlock, flags);
2947
2948         return ret;
2949 }
2950 EXPORT_SYMBOL_GPL(spi_async);
2951
2952 /**
2953  * spi_async_locked - version of spi_async with exclusive bus usage
2954  * @spi: device with which data will be exchanged
2955  * @message: describes the data transfers, including completion callback
2956  * Context: any (irqs may be blocked, etc)
2957  *
2958  * This call may be used in_irq and other contexts which can't sleep,
2959  * as well as from task contexts which can sleep.
2960  *
2961  * The completion callback is invoked in a context which can't sleep.
2962  * Before that invocation, the value of message->status is undefined.
2963  * When the callback is issued, message->status holds either zero (to
2964  * indicate complete success) or a negative error code.  After that
2965  * callback returns, the driver which issued the transfer request may
2966  * deallocate the associated memory; it's no longer in use by any SPI
2967  * core or controller driver code.
2968  *
2969  * Note that although all messages to a spi_device are handled in
2970  * FIFO order, messages may go to different devices in other orders.
2971  * Some device might be higher priority, or have various "hard" access
2972  * time requirements, for example.
2973  *
2974  * On detection of any fault during the transfer, processing of
2975  * the entire message is aborted, and the device is deselected.
2976  * Until returning from the associated message completion callback,
2977  * no other spi_message queued to that device will be processed.
2978  * (This rule applies equally to all the synchronous transfer calls,
2979  * which are wrappers around this core asynchronous primitive.)
2980  *
2981  * Return: zero on success, else a negative error code.
2982  */
2983 int spi_async_locked(struct spi_device *spi, struct spi_message *message)
2984 {
2985         struct spi_controller *ctlr = spi->controller;
2986         int ret;
2987         unsigned long flags;
2988
2989         ret = __spi_validate(spi, message);
2990         if (ret != 0)
2991                 return ret;
2992
2993         spin_lock_irqsave(&ctlr->bus_lock_spinlock, flags);
2994
2995         ret = __spi_async(spi, message);
2996
2997         spin_unlock_irqrestore(&ctlr->bus_lock_spinlock, flags);
2998
2999         return ret;
3000
3001 }
3002 EXPORT_SYMBOL_GPL(spi_async_locked);
3003
3004
3005 int spi_flash_read(struct spi_device *spi,
3006                    struct spi_flash_read_message *msg)
3007
3008 {
3009         struct spi_controller *master = spi->controller;
3010         struct device *rx_dev = NULL;
3011         int ret;
3012
3013         if ((msg->opcode_nbits == SPI_NBITS_DUAL ||
3014              msg->addr_nbits == SPI_NBITS_DUAL) &&
3015             !(spi->mode & (SPI_TX_DUAL | SPI_TX_QUAD)))
3016                 return -EINVAL;
3017         if ((msg->opcode_nbits == SPI_NBITS_QUAD ||
3018              msg->addr_nbits == SPI_NBITS_QUAD) &&
3019             !(spi->mode & SPI_TX_QUAD))
3020                 return -EINVAL;
3021         if (msg->data_nbits == SPI_NBITS_DUAL &&
3022             !(spi->mode & (SPI_RX_DUAL | SPI_RX_QUAD)))
3023                 return -EINVAL;
3024         if (msg->data_nbits == SPI_NBITS_QUAD &&
3025             !(spi->mode &  SPI_RX_QUAD))
3026                 return -EINVAL;
3027
3028         if (master->auto_runtime_pm) {
3029                 ret = pm_runtime_get_sync(master->dev.parent);
3030                 if (ret < 0) {
3031                         dev_err(&master->dev, "Failed to power device: %d\n",
3032                                 ret);
3033                         return ret;
3034                 }
3035         }
3036
3037         mutex_lock(&master->bus_lock_mutex);
3038         mutex_lock(&master->io_mutex);
3039         if (master->dma_rx && master->spi_flash_can_dma(spi, msg)) {
3040                 rx_dev = master->dma_rx->device->dev;
3041                 ret = spi_map_buf(master, rx_dev, &msg->rx_sg,
3042                                   msg->buf, msg->len,
3043                                   DMA_FROM_DEVICE);
3044                 if (!ret)
3045                         msg->cur_msg_mapped = true;
3046         }
3047         ret = master->spi_flash_read(spi, msg);
3048         if (msg->cur_msg_mapped)
3049                 spi_unmap_buf(master, rx_dev, &msg->rx_sg,
3050                               DMA_FROM_DEVICE);
3051         mutex_unlock(&master->io_mutex);
3052         mutex_unlock(&master->bus_lock_mutex);
3053
3054         if (master->auto_runtime_pm)
3055                 pm_runtime_put(master->dev.parent);
3056
3057         return ret;
3058 }
3059 EXPORT_SYMBOL_GPL(spi_flash_read);
3060
3061 /*-------------------------------------------------------------------------*/
3062
3063 /* Utility methods for SPI protocol drivers, layered on
3064  * top of the core.  Some other utility methods are defined as
3065  * inline functions.
3066  */
3067
3068 static void spi_complete(void *arg)
3069 {
3070         complete(arg);
3071 }
3072
3073 static int __spi_sync(struct spi_device *spi, struct spi_message *message)
3074 {
3075         DECLARE_COMPLETION_ONSTACK(done);
3076         int status;
3077         struct spi_controller *ctlr = spi->controller;
3078         unsigned long flags;
3079
3080         status = __spi_validate(spi, message);
3081         if (status != 0)
3082                 return status;
3083
3084         message->complete = spi_complete;
3085         message->context = &done;
3086         message->spi = spi;
3087
3088         SPI_STATISTICS_INCREMENT_FIELD(&ctlr->statistics, spi_sync);
3089         SPI_STATISTICS_INCREMENT_FIELD(&spi->statistics, spi_sync);
3090
3091         /* If we're not using the legacy transfer method then we will
3092          * try to transfer in the calling context so special case.
3093          * This code would be less tricky if we could remove the
3094          * support for driver implemented message queues.
3095          */
3096         if (ctlr->transfer == spi_queued_transfer) {
3097                 spin_lock_irqsave(&ctlr->bus_lock_spinlock, flags);
3098
3099                 trace_spi_message_submit(message);
3100
3101                 status = __spi_queued_transfer(spi, message, false);
3102
3103                 spin_unlock_irqrestore(&ctlr->bus_lock_spinlock, flags);
3104         } else {
3105                 status = spi_async_locked(spi, message);
3106         }
3107
3108         if (status == 0) {
3109                 /* Push out the messages in the calling context if we
3110                  * can.
3111                  */
3112                 if (ctlr->transfer == spi_queued_transfer) {
3113                         SPI_STATISTICS_INCREMENT_FIELD(&ctlr->statistics,
3114                                                        spi_sync_immediate);
3115                         SPI_STATISTICS_INCREMENT_FIELD(&spi->statistics,
3116                                                        spi_sync_immediate);
3117                         __spi_pump_messages(ctlr, false);
3118                 }
3119
3120                 wait_for_completion(&done);
3121                 status = message->status;
3122         }
3123         message->context = NULL;
3124         return status;
3125 }
3126
3127 /**
3128  * spi_sync - blocking/synchronous SPI data transfers
3129  * @spi: device with which data will be exchanged
3130  * @message: describes the data transfers
3131  * Context: can sleep
3132  *
3133  * This call may only be used from a context that may sleep.  The sleep
3134  * is non-interruptible, and has no timeout.  Low-overhead controller
3135  * drivers may DMA directly into and out of the message buffers.
3136  *
3137  * Note that the SPI device's chip select is active during the message,
3138  * and then is normally disabled between messages.  Drivers for some
3139  * frequently-used devices may want to minimize costs of selecting a chip,
3140  * by leaving it selected in anticipation that the next message will go
3141  * to the same chip.  (That may increase power usage.)
3142  *
3143  * Also, the caller is guaranteeing that the memory associated with the
3144  * message will not be freed before this call returns.
3145  *
3146  * Return: zero on success, else a negative error code.
3147  */
3148 int spi_sync(struct spi_device *spi, struct spi_message *message)
3149 {
3150         int ret;
3151
3152         mutex_lock(&spi->controller->bus_lock_mutex);
3153         ret = __spi_sync(spi, message);
3154         mutex_unlock(&spi->controller->bus_lock_mutex);
3155
3156         return ret;
3157 }
3158 EXPORT_SYMBOL_GPL(spi_sync);
3159
3160 /**
3161  * spi_sync_locked - version of spi_sync with exclusive bus usage
3162  * @spi: device with which data will be exchanged
3163  * @message: describes the data transfers
3164  * Context: can sleep
3165  *
3166  * This call may only be used from a context that may sleep.  The sleep
3167  * is non-interruptible, and has no timeout.  Low-overhead controller
3168  * drivers may DMA directly into and out of the message buffers.
3169  *
3170  * This call should be used by drivers that require exclusive access to the
3171  * SPI bus. It has to be preceded by a spi_bus_lock call. The SPI bus must
3172  * be released by a spi_bus_unlock call when the exclusive access is over.
3173  *
3174  * Return: zero on success, else a negative error code.
3175  */
3176 int spi_sync_locked(struct spi_device *spi, struct spi_message *message)
3177 {
3178         return __spi_sync(spi, message);
3179 }
3180 EXPORT_SYMBOL_GPL(spi_sync_locked);
3181
3182 /**
3183  * spi_bus_lock - obtain a lock for exclusive SPI bus usage
3184  * @ctlr: SPI bus master that should be locked for exclusive bus access
3185  * Context: can sleep
3186  *
3187  * This call may only be used from a context that may sleep.  The sleep
3188  * is non-interruptible, and has no timeout.
3189  *
3190  * This call should be used by drivers that require exclusive access to the
3191  * SPI bus. The SPI bus must be released by a spi_bus_unlock call when the
3192  * exclusive access is over. Data transfer must be done by spi_sync_locked
3193  * and spi_async_locked calls when the SPI bus lock is held.
3194  *
3195  * Return: always zero.
3196  */
3197 int spi_bus_lock(struct spi_controller *ctlr)
3198 {
3199         unsigned long flags;
3200
3201         mutex_lock(&ctlr->bus_lock_mutex);
3202
3203         spin_lock_irqsave(&ctlr->bus_lock_spinlock, flags);
3204         ctlr->bus_lock_flag = 1;
3205         spin_unlock_irqrestore(&ctlr->bus_lock_spinlock, flags);
3206
3207         /* mutex remains locked until spi_bus_unlock is called */
3208
3209         return 0;
3210 }
3211 EXPORT_SYMBOL_GPL(spi_bus_lock);
3212
3213 /**
3214  * spi_bus_unlock - release the lock for exclusive SPI bus usage
3215  * @ctlr: SPI bus master that was locked for exclusive bus access
3216  * Context: can sleep
3217  *
3218  * This call may only be used from a context that may sleep.  The sleep
3219  * is non-interruptible, and has no timeout.
3220  *
3221  * This call releases an SPI bus lock previously obtained by an spi_bus_lock
3222  * call.
3223  *
3224  * Return: always zero.
3225  */
3226 int spi_bus_unlock(struct spi_controller *ctlr)
3227 {
3228         ctlr->bus_lock_flag = 0;
3229
3230         mutex_unlock(&ctlr->bus_lock_mutex);
3231
3232         return 0;
3233 }
3234 EXPORT_SYMBOL_GPL(spi_bus_unlock);
3235
3236 /* portable code must never pass more than 32 bytes */
3237 #define SPI_BUFSIZ      max(32, SMP_CACHE_BYTES)
3238
3239 static u8       *buf;
3240
3241 /**
3242  * spi_write_then_read - SPI synchronous write followed by read
3243  * @spi: device with which data will be exchanged
3244  * @txbuf: data to be written (need not be dma-safe)
3245  * @n_tx: size of txbuf, in bytes
3246  * @rxbuf: buffer into which data will be read (need not be dma-safe)
3247  * @n_rx: size of rxbuf, in bytes
3248  * Context: can sleep
3249  *
3250  * This performs a half duplex MicroWire style transaction with the
3251  * device, sending txbuf and then reading rxbuf.  The return value
3252  * is zero for success, else a negative errno status code.
3253  * This call may only be used from a context that may sleep.
3254  *
3255  * Parameters to this routine are always copied using a small buffer;
3256  * portable code should never use this for more than 32 bytes.
3257  * Performance-sensitive or bulk transfer code should instead use
3258  * spi_{async,sync}() calls with dma-safe buffers.
3259  *
3260  * Return: zero on success, else a negative error code.
3261  */
3262 int spi_write_then_read(struct spi_device *spi,
3263                 const void *txbuf, unsigned n_tx,
3264                 void *rxbuf, unsigned n_rx)
3265 {
3266         static DEFINE_MUTEX(lock);
3267
3268         int                     status;
3269         struct spi_message      message;
3270         struct spi_transfer     x[2];
3271         u8                      *local_buf;
3272
3273         /* Use preallocated DMA-safe buffer if we can.  We can't avoid
3274          * copying here, (as a pure convenience thing), but we can
3275          * keep heap costs out of the hot path unless someone else is
3276          * using the pre-allocated buffer or the transfer is too large.
3277          */
3278         if ((n_tx + n_rx) > SPI_BUFSIZ || !mutex_trylock(&lock)) {
3279                 local_buf = kmalloc(max((unsigned)SPI_BUFSIZ, n_tx + n_rx),
3280                                     GFP_KERNEL | GFP_DMA);
3281                 if (!local_buf)
3282                         return -ENOMEM;
3283         } else {
3284                 local_buf = buf;
3285         }
3286
3287         spi_message_init(&message);
3288         memset(x, 0, sizeof(x));
3289         if (n_tx) {
3290                 x[0].len = n_tx;
3291                 spi_message_add_tail(&x[0], &message);
3292         }
3293         if (n_rx) {
3294                 x[1].len = n_rx;
3295                 spi_message_add_tail(&x[1], &message);
3296         }
3297
3298         memcpy(local_buf, txbuf, n_tx);
3299         x[0].tx_buf = local_buf;
3300         x[1].rx_buf = local_buf + n_tx;
3301
3302         /* do the i/o */
3303         status = spi_sync(spi, &message);
3304         if (status == 0)
3305                 memcpy(rxbuf, x[1].rx_buf, n_rx);
3306
3307         if (x[0].tx_buf == buf)
3308                 mutex_unlock(&lock);
3309         else
3310                 kfree(local_buf);
3311
3312         return status;
3313 }
3314 EXPORT_SYMBOL_GPL(spi_write_then_read);
3315
3316 /*-------------------------------------------------------------------------*/