Merge branch 'bkl-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git...
[sfrench/cifs-2.6.git] / drivers / spi / spidev.c
1 /*
2  * spidev.c -- simple synchronous userspace interface to SPI devices
3  *
4  * Copyright (C) 2006 SWAPP
5  *      Andrea Paterniani <a.paterniani@swapp-eng.it>
6  * Copyright (C) 2007 David Brownell (simplification, cleanup)
7  *
8  * This program is free software; you can redistribute it and/or modify
9  * it under the terms of the GNU General Public License as published by
10  * the Free Software Foundation; either version 2 of the License, or
11  * (at your option) any later version.
12  *
13  * This program is distributed in the hope that it will be useful,
14  * but WITHOUT ANY WARRANTY; without even the implied warranty of
15  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
16  * GNU General Public License for more details.
17  *
18  * You should have received a copy of the GNU General Public License
19  * along with this program; if not, write to the Free Software
20  * Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
21  */
22
23 #include <linux/init.h>
24 #include <linux/module.h>
25 #include <linux/ioctl.h>
26 #include <linux/fs.h>
27 #include <linux/device.h>
28 #include <linux/err.h>
29 #include <linux/list.h>
30 #include <linux/errno.h>
31 #include <linux/mutex.h>
32 #include <linux/slab.h>
33 #include <linux/smp_lock.h>
34
35 #include <linux/spi/spi.h>
36 #include <linux/spi/spidev.h>
37
38 #include <asm/uaccess.h>
39
40
41 /*
42  * This supports acccess to SPI devices using normal userspace I/O calls.
43  * Note that while traditional UNIX/POSIX I/O semantics are half duplex,
44  * and often mask message boundaries, full SPI support requires full duplex
45  * transfers.  There are several kinds of of internal message boundaries to
46  * handle chipselect management and other protocol options.
47  *
48  * SPI has a character major number assigned.  We allocate minor numbers
49  * dynamically using a bitmask.  You must use hotplug tools, such as udev
50  * (or mdev with busybox) to create and destroy the /dev/spidevB.C device
51  * nodes, since there is no fixed association of minor numbers with any
52  * particular SPI bus or device.
53  */
54 #define SPIDEV_MAJOR                    153     /* assigned */
55 #define N_SPI_MINORS                    32      /* ... up to 256 */
56
57 static unsigned long    minors[N_SPI_MINORS / BITS_PER_LONG];
58
59
60 /* Bit masks for spi_device.mode management.  Note that incorrect
61  * settings for some settings can cause *lots* of trouble for other
62  * devices on a shared bus:
63  *
64  *  - CS_HIGH ... this device will be active when it shouldn't be
65  *  - 3WIRE ... when active, it won't behave as it should
66  *  - NO_CS ... there will be no explicit message boundaries; this
67  *      is completely incompatible with the shared bus model
68  *  - READY ... transfers may proceed when they shouldn't.
69  *
70  * REVISIT should changing those flags be privileged?
71  */
72 #define SPI_MODE_MASK           (SPI_CPHA | SPI_CPOL | SPI_CS_HIGH \
73                                 | SPI_LSB_FIRST | SPI_3WIRE | SPI_LOOP \
74                                 | SPI_NO_CS | SPI_READY)
75
76 struct spidev_data {
77         dev_t                   devt;
78         spinlock_t              spi_lock;
79         struct spi_device       *spi;
80         struct list_head        device_entry;
81
82         /* buffer is NULL unless this device is open (users > 0) */
83         struct mutex            buf_lock;
84         unsigned                users;
85         u8                      *buffer;
86 };
87
88 static LIST_HEAD(device_list);
89 static DEFINE_MUTEX(device_list_lock);
90
91 static unsigned bufsiz = 4096;
92 module_param(bufsiz, uint, S_IRUGO);
93 MODULE_PARM_DESC(bufsiz, "data bytes in biggest supported SPI message");
94
95 /*-------------------------------------------------------------------------*/
96
97 /*
98  * We can't use the standard synchronous wrappers for file I/O; we
99  * need to protect against async removal of the underlying spi_device.
100  */
101 static void spidev_complete(void *arg)
102 {
103         complete(arg);
104 }
105
106 static ssize_t
107 spidev_sync(struct spidev_data *spidev, struct spi_message *message)
108 {
109         DECLARE_COMPLETION_ONSTACK(done);
110         int status;
111
112         message->complete = spidev_complete;
113         message->context = &done;
114
115         spin_lock_irq(&spidev->spi_lock);
116         if (spidev->spi == NULL)
117                 status = -ESHUTDOWN;
118         else
119                 status = spi_async(spidev->spi, message);
120         spin_unlock_irq(&spidev->spi_lock);
121
122         if (status == 0) {
123                 wait_for_completion(&done);
124                 status = message->status;
125                 if (status == 0)
126                         status = message->actual_length;
127         }
128         return status;
129 }
130
131 static inline ssize_t
132 spidev_sync_write(struct spidev_data *spidev, size_t len)
133 {
134         struct spi_transfer     t = {
135                         .tx_buf         = spidev->buffer,
136                         .len            = len,
137                 };
138         struct spi_message      m;
139
140         spi_message_init(&m);
141         spi_message_add_tail(&t, &m);
142         return spidev_sync(spidev, &m);
143 }
144
145 static inline ssize_t
146 spidev_sync_read(struct spidev_data *spidev, size_t len)
147 {
148         struct spi_transfer     t = {
149                         .rx_buf         = spidev->buffer,
150                         .len            = len,
151                 };
152         struct spi_message      m;
153
154         spi_message_init(&m);
155         spi_message_add_tail(&t, &m);
156         return spidev_sync(spidev, &m);
157 }
158
159 /*-------------------------------------------------------------------------*/
160
161 /* Read-only message with current device setup */
162 static ssize_t
163 spidev_read(struct file *filp, char __user *buf, size_t count, loff_t *f_pos)
164 {
165         struct spidev_data      *spidev;
166         ssize_t                 status = 0;
167
168         /* chipselect only toggles at start or end of operation */
169         if (count > bufsiz)
170                 return -EMSGSIZE;
171
172         spidev = filp->private_data;
173
174         mutex_lock(&spidev->buf_lock);
175         status = spidev_sync_read(spidev, count);
176         if (status > 0) {
177                 unsigned long   missing;
178
179                 missing = copy_to_user(buf, spidev->buffer, status);
180                 if (missing == status)
181                         status = -EFAULT;
182                 else
183                         status = status - missing;
184         }
185         mutex_unlock(&spidev->buf_lock);
186
187         return status;
188 }
189
190 /* Write-only message with current device setup */
191 static ssize_t
192 spidev_write(struct file *filp, const char __user *buf,
193                 size_t count, loff_t *f_pos)
194 {
195         struct spidev_data      *spidev;
196         ssize_t                 status = 0;
197         unsigned long           missing;
198
199         /* chipselect only toggles at start or end of operation */
200         if (count > bufsiz)
201                 return -EMSGSIZE;
202
203         spidev = filp->private_data;
204
205         mutex_lock(&spidev->buf_lock);
206         missing = copy_from_user(spidev->buffer, buf, count);
207         if (missing == 0) {
208                 status = spidev_sync_write(spidev, count);
209         } else
210                 status = -EFAULT;
211         mutex_unlock(&spidev->buf_lock);
212
213         return status;
214 }
215
216 static int spidev_message(struct spidev_data *spidev,
217                 struct spi_ioc_transfer *u_xfers, unsigned n_xfers)
218 {
219         struct spi_message      msg;
220         struct spi_transfer     *k_xfers;
221         struct spi_transfer     *k_tmp;
222         struct spi_ioc_transfer *u_tmp;
223         unsigned                n, total;
224         u8                      *buf;
225         int                     status = -EFAULT;
226
227         spi_message_init(&msg);
228         k_xfers = kcalloc(n_xfers, sizeof(*k_tmp), GFP_KERNEL);
229         if (k_xfers == NULL)
230                 return -ENOMEM;
231
232         /* Construct spi_message, copying any tx data to bounce buffer.
233          * We walk the array of user-provided transfers, using each one
234          * to initialize a kernel version of the same transfer.
235          */
236         buf = spidev->buffer;
237         total = 0;
238         for (n = n_xfers, k_tmp = k_xfers, u_tmp = u_xfers;
239                         n;
240                         n--, k_tmp++, u_tmp++) {
241                 k_tmp->len = u_tmp->len;
242
243                 total += k_tmp->len;
244                 if (total > bufsiz) {
245                         status = -EMSGSIZE;
246                         goto done;
247                 }
248
249                 if (u_tmp->rx_buf) {
250                         k_tmp->rx_buf = buf;
251                         if (!access_ok(VERIFY_WRITE, (u8 __user *)
252                                                 (uintptr_t) u_tmp->rx_buf,
253                                                 u_tmp->len))
254                                 goto done;
255                 }
256                 if (u_tmp->tx_buf) {
257                         k_tmp->tx_buf = buf;
258                         if (copy_from_user(buf, (const u8 __user *)
259                                                 (uintptr_t) u_tmp->tx_buf,
260                                         u_tmp->len))
261                                 goto done;
262                 }
263                 buf += k_tmp->len;
264
265                 k_tmp->cs_change = !!u_tmp->cs_change;
266                 k_tmp->bits_per_word = u_tmp->bits_per_word;
267                 k_tmp->delay_usecs = u_tmp->delay_usecs;
268                 k_tmp->speed_hz = u_tmp->speed_hz;
269 #ifdef VERBOSE
270                 dev_dbg(&spi->dev,
271                         "  xfer len %zd %s%s%s%dbits %u usec %uHz\n",
272                         u_tmp->len,
273                         u_tmp->rx_buf ? "rx " : "",
274                         u_tmp->tx_buf ? "tx " : "",
275                         u_tmp->cs_change ? "cs " : "",
276                         u_tmp->bits_per_word ? : spi->bits_per_word,
277                         u_tmp->delay_usecs,
278                         u_tmp->speed_hz ? : spi->max_speed_hz);
279 #endif
280                 spi_message_add_tail(k_tmp, &msg);
281         }
282
283         status = spidev_sync(spidev, &msg);
284         if (status < 0)
285                 goto done;
286
287         /* copy any rx data out of bounce buffer */
288         buf = spidev->buffer;
289         for (n = n_xfers, u_tmp = u_xfers; n; n--, u_tmp++) {
290                 if (u_tmp->rx_buf) {
291                         if (__copy_to_user((u8 __user *)
292                                         (uintptr_t) u_tmp->rx_buf, buf,
293                                         u_tmp->len)) {
294                                 status = -EFAULT;
295                                 goto done;
296                         }
297                 }
298                 buf += u_tmp->len;
299         }
300         status = total;
301
302 done:
303         kfree(k_xfers);
304         return status;
305 }
306
307 static long
308 spidev_ioctl(struct file *filp, unsigned int cmd, unsigned long arg)
309 {
310         int                     err = 0;
311         int                     retval = 0;
312         struct spidev_data      *spidev;
313         struct spi_device       *spi;
314         u32                     tmp;
315         unsigned                n_ioc;
316         struct spi_ioc_transfer *ioc;
317
318         /* Check type and command number */
319         if (_IOC_TYPE(cmd) != SPI_IOC_MAGIC)
320                 return -ENOTTY;
321
322         /* Check access direction once here; don't repeat below.
323          * IOC_DIR is from the user perspective, while access_ok is
324          * from the kernel perspective; so they look reversed.
325          */
326         if (_IOC_DIR(cmd) & _IOC_READ)
327                 err = !access_ok(VERIFY_WRITE,
328                                 (void __user *)arg, _IOC_SIZE(cmd));
329         if (err == 0 && _IOC_DIR(cmd) & _IOC_WRITE)
330                 err = !access_ok(VERIFY_READ,
331                                 (void __user *)arg, _IOC_SIZE(cmd));
332         if (err)
333                 return -EFAULT;
334
335         /* guard against device removal before, or while,
336          * we issue this ioctl.
337          */
338         spidev = filp->private_data;
339         spin_lock_irq(&spidev->spi_lock);
340         spi = spi_dev_get(spidev->spi);
341         spin_unlock_irq(&spidev->spi_lock);
342
343         if (spi == NULL)
344                 return -ESHUTDOWN;
345
346         /* use the buffer lock here for triple duty:
347          *  - prevent I/O (from us) so calling spi_setup() is safe;
348          *  - prevent concurrent SPI_IOC_WR_* from morphing
349          *    data fields while SPI_IOC_RD_* reads them;
350          *  - SPI_IOC_MESSAGE needs the buffer locked "normally".
351          */
352         mutex_lock(&spidev->buf_lock);
353
354         switch (cmd) {
355         /* read requests */
356         case SPI_IOC_RD_MODE:
357                 retval = __put_user(spi->mode & SPI_MODE_MASK,
358                                         (__u8 __user *)arg);
359                 break;
360         case SPI_IOC_RD_LSB_FIRST:
361                 retval = __put_user((spi->mode & SPI_LSB_FIRST) ?  1 : 0,
362                                         (__u8 __user *)arg);
363                 break;
364         case SPI_IOC_RD_BITS_PER_WORD:
365                 retval = __put_user(spi->bits_per_word, (__u8 __user *)arg);
366                 break;
367         case SPI_IOC_RD_MAX_SPEED_HZ:
368                 retval = __put_user(spi->max_speed_hz, (__u32 __user *)arg);
369                 break;
370
371         /* write requests */
372         case SPI_IOC_WR_MODE:
373                 retval = __get_user(tmp, (u8 __user *)arg);
374                 if (retval == 0) {
375                         u8      save = spi->mode;
376
377                         if (tmp & ~SPI_MODE_MASK) {
378                                 retval = -EINVAL;
379                                 break;
380                         }
381
382                         tmp |= spi->mode & ~SPI_MODE_MASK;
383                         spi->mode = (u8)tmp;
384                         retval = spi_setup(spi);
385                         if (retval < 0)
386                                 spi->mode = save;
387                         else
388                                 dev_dbg(&spi->dev, "spi mode %02x\n", tmp);
389                 }
390                 break;
391         case SPI_IOC_WR_LSB_FIRST:
392                 retval = __get_user(tmp, (__u8 __user *)arg);
393                 if (retval == 0) {
394                         u8      save = spi->mode;
395
396                         if (tmp)
397                                 spi->mode |= SPI_LSB_FIRST;
398                         else
399                                 spi->mode &= ~SPI_LSB_FIRST;
400                         retval = spi_setup(spi);
401                         if (retval < 0)
402                                 spi->mode = save;
403                         else
404                                 dev_dbg(&spi->dev, "%csb first\n",
405                                                 tmp ? 'l' : 'm');
406                 }
407                 break;
408         case SPI_IOC_WR_BITS_PER_WORD:
409                 retval = __get_user(tmp, (__u8 __user *)arg);
410                 if (retval == 0) {
411                         u8      save = spi->bits_per_word;
412
413                         spi->bits_per_word = tmp;
414                         retval = spi_setup(spi);
415                         if (retval < 0)
416                                 spi->bits_per_word = save;
417                         else
418                                 dev_dbg(&spi->dev, "%d bits per word\n", tmp);
419                 }
420                 break;
421         case SPI_IOC_WR_MAX_SPEED_HZ:
422                 retval = __get_user(tmp, (__u32 __user *)arg);
423                 if (retval == 0) {
424                         u32     save = spi->max_speed_hz;
425
426                         spi->max_speed_hz = tmp;
427                         retval = spi_setup(spi);
428                         if (retval < 0)
429                                 spi->max_speed_hz = save;
430                         else
431                                 dev_dbg(&spi->dev, "%d Hz (max)\n", tmp);
432                 }
433                 break;
434
435         default:
436                 /* segmented and/or full-duplex I/O request */
437                 if (_IOC_NR(cmd) != _IOC_NR(SPI_IOC_MESSAGE(0))
438                                 || _IOC_DIR(cmd) != _IOC_WRITE) {
439                         retval = -ENOTTY;
440                         break;
441                 }
442
443                 tmp = _IOC_SIZE(cmd);
444                 if ((tmp % sizeof(struct spi_ioc_transfer)) != 0) {
445                         retval = -EINVAL;
446                         break;
447                 }
448                 n_ioc = tmp / sizeof(struct spi_ioc_transfer);
449                 if (n_ioc == 0)
450                         break;
451
452                 /* copy into scratch area */
453                 ioc = kmalloc(tmp, GFP_KERNEL);
454                 if (!ioc) {
455                         retval = -ENOMEM;
456                         break;
457                 }
458                 if (__copy_from_user(ioc, (void __user *)arg, tmp)) {
459                         kfree(ioc);
460                         retval = -EFAULT;
461                         break;
462                 }
463
464                 /* translate to spi_message, execute */
465                 retval = spidev_message(spidev, ioc, n_ioc);
466                 kfree(ioc);
467                 break;
468         }
469
470         mutex_unlock(&spidev->buf_lock);
471         spi_dev_put(spi);
472         return retval;
473 }
474
475 static int spidev_open(struct inode *inode, struct file *filp)
476 {
477         struct spidev_data      *spidev;
478         int                     status = -ENXIO;
479
480         lock_kernel();
481         mutex_lock(&device_list_lock);
482
483         list_for_each_entry(spidev, &device_list, device_entry) {
484                 if (spidev->devt == inode->i_rdev) {
485                         status = 0;
486                         break;
487                 }
488         }
489         if (status == 0) {
490                 if (!spidev->buffer) {
491                         spidev->buffer = kmalloc(bufsiz, GFP_KERNEL);
492                         if (!spidev->buffer) {
493                                 dev_dbg(&spidev->spi->dev, "open/ENOMEM\n");
494                                 status = -ENOMEM;
495                         }
496                 }
497                 if (status == 0) {
498                         spidev->users++;
499                         filp->private_data = spidev;
500                         nonseekable_open(inode, filp);
501                 }
502         } else
503                 pr_debug("spidev: nothing for minor %d\n", iminor(inode));
504
505         mutex_unlock(&device_list_lock);
506         unlock_kernel();
507         return status;
508 }
509
510 static int spidev_release(struct inode *inode, struct file *filp)
511 {
512         struct spidev_data      *spidev;
513         int                     status = 0;
514
515         mutex_lock(&device_list_lock);
516         spidev = filp->private_data;
517         filp->private_data = NULL;
518
519         /* last close? */
520         spidev->users--;
521         if (!spidev->users) {
522                 int             dofree;
523
524                 kfree(spidev->buffer);
525                 spidev->buffer = NULL;
526
527                 /* ... after we unbound from the underlying device? */
528                 spin_lock_irq(&spidev->spi_lock);
529                 dofree = (spidev->spi == NULL);
530                 spin_unlock_irq(&spidev->spi_lock);
531
532                 if (dofree)
533                         kfree(spidev);
534         }
535         mutex_unlock(&device_list_lock);
536
537         return status;
538 }
539
540 static const struct file_operations spidev_fops = {
541         .owner =        THIS_MODULE,
542         /* REVISIT switch to aio primitives, so that userspace
543          * gets more complete API coverage.  It'll simplify things
544          * too, except for the locking.
545          */
546         .write =        spidev_write,
547         .read =         spidev_read,
548         .unlocked_ioctl = spidev_ioctl,
549         .open =         spidev_open,
550         .release =      spidev_release,
551 };
552
553 /*-------------------------------------------------------------------------*/
554
555 /* The main reason to have this class is to make mdev/udev create the
556  * /dev/spidevB.C character device nodes exposing our userspace API.
557  * It also simplifies memory management.
558  */
559
560 static struct class *spidev_class;
561
562 /*-------------------------------------------------------------------------*/
563
564 static int spidev_probe(struct spi_device *spi)
565 {
566         struct spidev_data      *spidev;
567         int                     status;
568         unsigned long           minor;
569
570         /* Allocate driver data */
571         spidev = kzalloc(sizeof(*spidev), GFP_KERNEL);
572         if (!spidev)
573                 return -ENOMEM;
574
575         /* Initialize the driver data */
576         spidev->spi = spi;
577         spin_lock_init(&spidev->spi_lock);
578         mutex_init(&spidev->buf_lock);
579
580         INIT_LIST_HEAD(&spidev->device_entry);
581
582         /* If we can allocate a minor number, hook up this device.
583          * Reusing minors is fine so long as udev or mdev is working.
584          */
585         mutex_lock(&device_list_lock);
586         minor = find_first_zero_bit(minors, N_SPI_MINORS);
587         if (minor < N_SPI_MINORS) {
588                 struct device *dev;
589
590                 spidev->devt = MKDEV(SPIDEV_MAJOR, minor);
591                 dev = device_create(spidev_class, &spi->dev, spidev->devt,
592                                     spidev, "spidev%d.%d",
593                                     spi->master->bus_num, spi->chip_select);
594                 status = IS_ERR(dev) ? PTR_ERR(dev) : 0;
595         } else {
596                 dev_dbg(&spi->dev, "no minor number available!\n");
597                 status = -ENODEV;
598         }
599         if (status == 0) {
600                 set_bit(minor, minors);
601                 list_add(&spidev->device_entry, &device_list);
602         }
603         mutex_unlock(&device_list_lock);
604
605         if (status == 0)
606                 spi_set_drvdata(spi, spidev);
607         else
608                 kfree(spidev);
609
610         return status;
611 }
612
613 static int spidev_remove(struct spi_device *spi)
614 {
615         struct spidev_data      *spidev = spi_get_drvdata(spi);
616
617         /* make sure ops on existing fds can abort cleanly */
618         spin_lock_irq(&spidev->spi_lock);
619         spidev->spi = NULL;
620         spi_set_drvdata(spi, NULL);
621         spin_unlock_irq(&spidev->spi_lock);
622
623         /* prevent new opens */
624         mutex_lock(&device_list_lock);
625         list_del(&spidev->device_entry);
626         device_destroy(spidev_class, spidev->devt);
627         clear_bit(MINOR(spidev->devt), minors);
628         if (spidev->users == 0)
629                 kfree(spidev);
630         mutex_unlock(&device_list_lock);
631
632         return 0;
633 }
634
635 static struct spi_driver spidev_spi = {
636         .driver = {
637                 .name =         "spidev",
638                 .owner =        THIS_MODULE,
639         },
640         .probe =        spidev_probe,
641         .remove =       __devexit_p(spidev_remove),
642
643         /* NOTE:  suspend/resume methods are not necessary here.
644          * We don't do anything except pass the requests to/from
645          * the underlying controller.  The refrigerator handles
646          * most issues; the controller driver handles the rest.
647          */
648 };
649
650 /*-------------------------------------------------------------------------*/
651
652 static int __init spidev_init(void)
653 {
654         int status;
655
656         /* Claim our 256 reserved device numbers.  Then register a class
657          * that will key udev/mdev to add/remove /dev nodes.  Last, register
658          * the driver which manages those device numbers.
659          */
660         BUILD_BUG_ON(N_SPI_MINORS > 256);
661         status = register_chrdev(SPIDEV_MAJOR, "spi", &spidev_fops);
662         if (status < 0)
663                 return status;
664
665         spidev_class = class_create(THIS_MODULE, "spidev");
666         if (IS_ERR(spidev_class)) {
667                 unregister_chrdev(SPIDEV_MAJOR, spidev_spi.driver.name);
668                 return PTR_ERR(spidev_class);
669         }
670
671         status = spi_register_driver(&spidev_spi);
672         if (status < 0) {
673                 class_destroy(spidev_class);
674                 unregister_chrdev(SPIDEV_MAJOR, spidev_spi.driver.name);
675         }
676         return status;
677 }
678 module_init(spidev_init);
679
680 static void __exit spidev_exit(void)
681 {
682         spi_unregister_driver(&spidev_spi);
683         class_destroy(spidev_class);
684         unregister_chrdev(SPIDEV_MAJOR, spidev_spi.driver.name);
685 }
686 module_exit(spidev_exit);
687
688 MODULE_AUTHOR("Andrea Paterniani, <a.paterniani@swapp-eng.it>");
689 MODULE_DESCRIPTION("User mode SPI device interface");
690 MODULE_LICENSE("GPL");
691 MODULE_ALIAS("spi:spidev");