Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs-2.6
[sfrench/cifs-2.6.git] / drivers / firewire / core-device.c
1 /*
2  * Device probing and sysfs code.
3  *
4  * Copyright (C) 2005-2006  Kristian Hoegsberg <krh@bitplanet.net>
5  *
6  * This program is free software; you can redistribute it and/or modify
7  * it under the terms of the GNU General Public License as published by
8  * the Free Software Foundation; either version 2 of the License, or
9  * (at your option) any later version.
10  *
11  * This program is distributed in the hope that it will be useful,
12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
14  * GNU General Public License for more details.
15  *
16  * You should have received a copy of the GNU General Public License
17  * along with this program; if not, write to the Free Software Foundation,
18  * Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
19  */
20
21 #include <linux/bug.h>
22 #include <linux/ctype.h>
23 #include <linux/delay.h>
24 #include <linux/device.h>
25 #include <linux/errno.h>
26 #include <linux/firewire.h>
27 #include <linux/firewire-constants.h>
28 #include <linux/idr.h>
29 #include <linux/jiffies.h>
30 #include <linux/kobject.h>
31 #include <linux/list.h>
32 #include <linux/mod_devicetable.h>
33 #include <linux/module.h>
34 #include <linux/mutex.h>
35 #include <linux/rwsem.h>
36 #include <linux/spinlock.h>
37 #include <linux/string.h>
38 #include <linux/workqueue.h>
39
40 #include <asm/atomic.h>
41 #include <asm/byteorder.h>
42 #include <asm/system.h>
43
44 #include "core.h"
45
46 void fw_csr_iterator_init(struct fw_csr_iterator *ci, const u32 *p)
47 {
48         ci->p = p + 1;
49         ci->end = ci->p + (p[0] >> 16);
50 }
51 EXPORT_SYMBOL(fw_csr_iterator_init);
52
53 int fw_csr_iterator_next(struct fw_csr_iterator *ci, int *key, int *value)
54 {
55         *key = *ci->p >> 24;
56         *value = *ci->p & 0xffffff;
57
58         return ci->p++ < ci->end;
59 }
60 EXPORT_SYMBOL(fw_csr_iterator_next);
61
62 static const u32 *search_leaf(const u32 *directory, int search_key)
63 {
64         struct fw_csr_iterator ci;
65         int last_key = 0, key, value;
66
67         fw_csr_iterator_init(&ci, directory);
68         while (fw_csr_iterator_next(&ci, &key, &value)) {
69                 if (last_key == search_key &&
70                     key == (CSR_DESCRIPTOR | CSR_LEAF))
71                         return ci.p - 1 + value;
72
73                 last_key = key;
74         }
75
76         return NULL;
77 }
78
79 static int textual_leaf_to_string(const u32 *block, char *buf, size_t size)
80 {
81         unsigned int quadlets, i;
82         char c;
83
84         if (!size || !buf)
85                 return -EINVAL;
86
87         quadlets = min(block[0] >> 16, 256U);
88         if (quadlets < 2)
89                 return -ENODATA;
90
91         if (block[1] != 0 || block[2] != 0)
92                 /* unknown language/character set */
93                 return -ENODATA;
94
95         block += 3;
96         quadlets -= 2;
97         for (i = 0; i < quadlets * 4 && i < size - 1; i++) {
98                 c = block[i / 4] >> (24 - 8 * (i % 4));
99                 if (c == '\0')
100                         break;
101                 buf[i] = c;
102         }
103         buf[i] = '\0';
104
105         return i;
106 }
107
108 /**
109  * fw_csr_string - reads a string from the configuration ROM
110  * @directory: e.g. root directory or unit directory
111  * @key: the key of the preceding directory entry
112  * @buf: where to put the string
113  * @size: size of @buf, in bytes
114  *
115  * The string is taken from a minimal ASCII text descriptor leaf after
116  * the immediate entry with @key.  The string is zero-terminated.
117  * Returns strlen(buf) or a negative error code.
118  */
119 int fw_csr_string(const u32 *directory, int key, char *buf, size_t size)
120 {
121         const u32 *leaf = search_leaf(directory, key);
122         if (!leaf)
123                 return -ENOENT;
124
125         return textual_leaf_to_string(leaf, buf, size);
126 }
127 EXPORT_SYMBOL(fw_csr_string);
128
129 static bool is_fw_unit(struct device *dev);
130
131 static int match_unit_directory(const u32 *directory, u32 match_flags,
132                                 const struct ieee1394_device_id *id)
133 {
134         struct fw_csr_iterator ci;
135         int key, value, match;
136
137         match = 0;
138         fw_csr_iterator_init(&ci, directory);
139         while (fw_csr_iterator_next(&ci, &key, &value)) {
140                 if (key == CSR_VENDOR && value == id->vendor_id)
141                         match |= IEEE1394_MATCH_VENDOR_ID;
142                 if (key == CSR_MODEL && value == id->model_id)
143                         match |= IEEE1394_MATCH_MODEL_ID;
144                 if (key == CSR_SPECIFIER_ID && value == id->specifier_id)
145                         match |= IEEE1394_MATCH_SPECIFIER_ID;
146                 if (key == CSR_VERSION && value == id->version)
147                         match |= IEEE1394_MATCH_VERSION;
148         }
149
150         return (match & match_flags) == match_flags;
151 }
152
153 static int fw_unit_match(struct device *dev, struct device_driver *drv)
154 {
155         struct fw_unit *unit = fw_unit(dev);
156         struct fw_device *device;
157         const struct ieee1394_device_id *id;
158
159         /* We only allow binding to fw_units. */
160         if (!is_fw_unit(dev))
161                 return 0;
162
163         device = fw_parent_device(unit);
164         id = container_of(drv, struct fw_driver, driver)->id_table;
165
166         for (; id->match_flags != 0; id++) {
167                 if (match_unit_directory(unit->directory, id->match_flags, id))
168                         return 1;
169
170                 /* Also check vendor ID in the root directory. */
171                 if ((id->match_flags & IEEE1394_MATCH_VENDOR_ID) &&
172                     match_unit_directory(&device->config_rom[5],
173                                 IEEE1394_MATCH_VENDOR_ID, id) &&
174                     match_unit_directory(unit->directory, id->match_flags
175                                 & ~IEEE1394_MATCH_VENDOR_ID, id))
176                         return 1;
177         }
178
179         return 0;
180 }
181
182 static int get_modalias(struct fw_unit *unit, char *buffer, size_t buffer_size)
183 {
184         struct fw_device *device = fw_parent_device(unit);
185         struct fw_csr_iterator ci;
186
187         int key, value;
188         int vendor = 0;
189         int model = 0;
190         int specifier_id = 0;
191         int version = 0;
192
193         fw_csr_iterator_init(&ci, &device->config_rom[5]);
194         while (fw_csr_iterator_next(&ci, &key, &value)) {
195                 switch (key) {
196                 case CSR_VENDOR:
197                         vendor = value;
198                         break;
199                 case CSR_MODEL:
200                         model = value;
201                         break;
202                 }
203         }
204
205         fw_csr_iterator_init(&ci, unit->directory);
206         while (fw_csr_iterator_next(&ci, &key, &value)) {
207                 switch (key) {
208                 case CSR_SPECIFIER_ID:
209                         specifier_id = value;
210                         break;
211                 case CSR_VERSION:
212                         version = value;
213                         break;
214                 }
215         }
216
217         return snprintf(buffer, buffer_size,
218                         "ieee1394:ven%08Xmo%08Xsp%08Xver%08X",
219                         vendor, model, specifier_id, version);
220 }
221
222 static int fw_unit_uevent(struct device *dev, struct kobj_uevent_env *env)
223 {
224         struct fw_unit *unit = fw_unit(dev);
225         char modalias[64];
226
227         get_modalias(unit, modalias, sizeof(modalias));
228
229         if (add_uevent_var(env, "MODALIAS=%s", modalias))
230                 return -ENOMEM;
231
232         return 0;
233 }
234
235 struct bus_type fw_bus_type = {
236         .name = "firewire",
237         .match = fw_unit_match,
238 };
239 EXPORT_SYMBOL(fw_bus_type);
240
241 int fw_device_enable_phys_dma(struct fw_device *device)
242 {
243         int generation = device->generation;
244
245         /* device->node_id, accessed below, must not be older than generation */
246         smp_rmb();
247
248         return device->card->driver->enable_phys_dma(device->card,
249                                                      device->node_id,
250                                                      generation);
251 }
252 EXPORT_SYMBOL(fw_device_enable_phys_dma);
253
254 struct config_rom_attribute {
255         struct device_attribute attr;
256         u32 key;
257 };
258
259 static ssize_t show_immediate(struct device *dev,
260                               struct device_attribute *dattr, char *buf)
261 {
262         struct config_rom_attribute *attr =
263                 container_of(dattr, struct config_rom_attribute, attr);
264         struct fw_csr_iterator ci;
265         const u32 *dir;
266         int key, value, ret = -ENOENT;
267
268         down_read(&fw_device_rwsem);
269
270         if (is_fw_unit(dev))
271                 dir = fw_unit(dev)->directory;
272         else
273                 dir = fw_device(dev)->config_rom + 5;
274
275         fw_csr_iterator_init(&ci, dir);
276         while (fw_csr_iterator_next(&ci, &key, &value))
277                 if (attr->key == key) {
278                         ret = snprintf(buf, buf ? PAGE_SIZE : 0,
279                                        "0x%06x\n", value);
280                         break;
281                 }
282
283         up_read(&fw_device_rwsem);
284
285         return ret;
286 }
287
288 #define IMMEDIATE_ATTR(name, key)                               \
289         { __ATTR(name, S_IRUGO, show_immediate, NULL), key }
290
291 static ssize_t show_text_leaf(struct device *dev,
292                               struct device_attribute *dattr, char *buf)
293 {
294         struct config_rom_attribute *attr =
295                 container_of(dattr, struct config_rom_attribute, attr);
296         const u32 *dir;
297         size_t bufsize;
298         char dummy_buf[2];
299         int ret;
300
301         down_read(&fw_device_rwsem);
302
303         if (is_fw_unit(dev))
304                 dir = fw_unit(dev)->directory;
305         else
306                 dir = fw_device(dev)->config_rom + 5;
307
308         if (buf) {
309                 bufsize = PAGE_SIZE - 1;
310         } else {
311                 buf = dummy_buf;
312                 bufsize = 1;
313         }
314
315         ret = fw_csr_string(dir, attr->key, buf, bufsize);
316
317         if (ret >= 0) {
318                 /* Strip trailing whitespace and add newline. */
319                 while (ret > 0 && isspace(buf[ret - 1]))
320                         ret--;
321                 strcpy(buf + ret, "\n");
322                 ret++;
323         }
324
325         up_read(&fw_device_rwsem);
326
327         return ret;
328 }
329
330 #define TEXT_LEAF_ATTR(name, key)                               \
331         { __ATTR(name, S_IRUGO, show_text_leaf, NULL), key }
332
333 static struct config_rom_attribute config_rom_attributes[] = {
334         IMMEDIATE_ATTR(vendor, CSR_VENDOR),
335         IMMEDIATE_ATTR(hardware_version, CSR_HARDWARE_VERSION),
336         IMMEDIATE_ATTR(specifier_id, CSR_SPECIFIER_ID),
337         IMMEDIATE_ATTR(version, CSR_VERSION),
338         IMMEDIATE_ATTR(model, CSR_MODEL),
339         TEXT_LEAF_ATTR(vendor_name, CSR_VENDOR),
340         TEXT_LEAF_ATTR(model_name, CSR_MODEL),
341         TEXT_LEAF_ATTR(hardware_version_name, CSR_HARDWARE_VERSION),
342 };
343
344 static void init_fw_attribute_group(struct device *dev,
345                                     struct device_attribute *attrs,
346                                     struct fw_attribute_group *group)
347 {
348         struct device_attribute *attr;
349         int i, j;
350
351         for (j = 0; attrs[j].attr.name != NULL; j++)
352                 group->attrs[j] = &attrs[j].attr;
353
354         for (i = 0; i < ARRAY_SIZE(config_rom_attributes); i++) {
355                 attr = &config_rom_attributes[i].attr;
356                 if (attr->show(dev, attr, NULL) < 0)
357                         continue;
358                 group->attrs[j++] = &attr->attr;
359         }
360
361         group->attrs[j] = NULL;
362         group->groups[0] = &group->group;
363         group->groups[1] = NULL;
364         group->group.attrs = group->attrs;
365         dev->groups = (const struct attribute_group **) group->groups;
366 }
367
368 static ssize_t modalias_show(struct device *dev,
369                              struct device_attribute *attr, char *buf)
370 {
371         struct fw_unit *unit = fw_unit(dev);
372         int length;
373
374         length = get_modalias(unit, buf, PAGE_SIZE);
375         strcpy(buf + length, "\n");
376
377         return length + 1;
378 }
379
380 static ssize_t rom_index_show(struct device *dev,
381                               struct device_attribute *attr, char *buf)
382 {
383         struct fw_device *device = fw_device(dev->parent);
384         struct fw_unit *unit = fw_unit(dev);
385
386         return snprintf(buf, PAGE_SIZE, "%d\n",
387                         (int)(unit->directory - device->config_rom));
388 }
389
390 static struct device_attribute fw_unit_attributes[] = {
391         __ATTR_RO(modalias),
392         __ATTR_RO(rom_index),
393         __ATTR_NULL,
394 };
395
396 static ssize_t config_rom_show(struct device *dev,
397                                struct device_attribute *attr, char *buf)
398 {
399         struct fw_device *device = fw_device(dev);
400         size_t length;
401
402         down_read(&fw_device_rwsem);
403         length = device->config_rom_length * 4;
404         memcpy(buf, device->config_rom, length);
405         up_read(&fw_device_rwsem);
406
407         return length;
408 }
409
410 static ssize_t guid_show(struct device *dev,
411                          struct device_attribute *attr, char *buf)
412 {
413         struct fw_device *device = fw_device(dev);
414         int ret;
415
416         down_read(&fw_device_rwsem);
417         ret = snprintf(buf, PAGE_SIZE, "0x%08x%08x\n",
418                        device->config_rom[3], device->config_rom[4]);
419         up_read(&fw_device_rwsem);
420
421         return ret;
422 }
423
424 static int units_sprintf(char *buf, const u32 *directory)
425 {
426         struct fw_csr_iterator ci;
427         int key, value;
428         int specifier_id = 0;
429         int version = 0;
430
431         fw_csr_iterator_init(&ci, directory);
432         while (fw_csr_iterator_next(&ci, &key, &value)) {
433                 switch (key) {
434                 case CSR_SPECIFIER_ID:
435                         specifier_id = value;
436                         break;
437                 case CSR_VERSION:
438                         version = value;
439                         break;
440                 }
441         }
442
443         return sprintf(buf, "0x%06x:0x%06x ", specifier_id, version);
444 }
445
446 static ssize_t units_show(struct device *dev,
447                           struct device_attribute *attr, char *buf)
448 {
449         struct fw_device *device = fw_device(dev);
450         struct fw_csr_iterator ci;
451         int key, value, i = 0;
452
453         down_read(&fw_device_rwsem);
454         fw_csr_iterator_init(&ci, &device->config_rom[5]);
455         while (fw_csr_iterator_next(&ci, &key, &value)) {
456                 if (key != (CSR_UNIT | CSR_DIRECTORY))
457                         continue;
458                 i += units_sprintf(&buf[i], ci.p + value - 1);
459                 if (i >= PAGE_SIZE - (8 + 1 + 8 + 1))
460                         break;
461         }
462         up_read(&fw_device_rwsem);
463
464         if (i)
465                 buf[i - 1] = '\n';
466
467         return i;
468 }
469
470 static struct device_attribute fw_device_attributes[] = {
471         __ATTR_RO(config_rom),
472         __ATTR_RO(guid),
473         __ATTR_RO(units),
474         __ATTR_NULL,
475 };
476
477 static int read_rom(struct fw_device *device,
478                     int generation, int index, u32 *data)
479 {
480         int rcode;
481
482         /* device->node_id, accessed below, must not be older than generation */
483         smp_rmb();
484
485         rcode = fw_run_transaction(device->card, TCODE_READ_QUADLET_REQUEST,
486                         device->node_id, generation, device->max_speed,
487                         (CSR_REGISTER_BASE | CSR_CONFIG_ROM) + index * 4,
488                         data, 4);
489         be32_to_cpus(data);
490
491         return rcode;
492 }
493
494 #define MAX_CONFIG_ROM_SIZE 256
495
496 /*
497  * Read the bus info block, perform a speed probe, and read all of the rest of
498  * the config ROM.  We do all this with a cached bus generation.  If the bus
499  * generation changes under us, read_config_rom will fail and get retried.
500  * It's better to start all over in this case because the node from which we
501  * are reading the ROM may have changed the ROM during the reset.
502  */
503 static int read_config_rom(struct fw_device *device, int generation)
504 {
505         const u32 *old_rom, *new_rom;
506         u32 *rom, *stack;
507         u32 sp, key;
508         int i, end, length, ret = -1;
509
510         rom = kmalloc(sizeof(*rom) * MAX_CONFIG_ROM_SIZE +
511                       sizeof(*stack) * MAX_CONFIG_ROM_SIZE, GFP_KERNEL);
512         if (rom == NULL)
513                 return -ENOMEM;
514
515         stack = &rom[MAX_CONFIG_ROM_SIZE];
516         memset(rom, 0, sizeof(*rom) * MAX_CONFIG_ROM_SIZE);
517
518         device->max_speed = SCODE_100;
519
520         /* First read the bus info block. */
521         for (i = 0; i < 5; i++) {
522                 if (read_rom(device, generation, i, &rom[i]) != RCODE_COMPLETE)
523                         goto out;
524                 /*
525                  * As per IEEE1212 7.2, during power-up, devices can
526                  * reply with a 0 for the first quadlet of the config
527                  * rom to indicate that they are booting (for example,
528                  * if the firmware is on the disk of a external
529                  * harddisk).  In that case we just fail, and the
530                  * retry mechanism will try again later.
531                  */
532                 if (i == 0 && rom[i] == 0)
533                         goto out;
534         }
535
536         device->max_speed = device->node->max_speed;
537
538         /*
539          * Determine the speed of
540          *   - devices with link speed less than PHY speed,
541          *   - devices with 1394b PHY (unless only connected to 1394a PHYs),
542          *   - all devices if there are 1394b repeaters.
543          * Note, we cannot use the bus info block's link_spd as starting point
544          * because some buggy firmwares set it lower than necessary and because
545          * 1394-1995 nodes do not have the field.
546          */
547         if ((rom[2] & 0x7) < device->max_speed ||
548             device->max_speed == SCODE_BETA ||
549             device->card->beta_repeaters_present) {
550                 u32 dummy;
551
552                 /* for S1600 and S3200 */
553                 if (device->max_speed == SCODE_BETA)
554                         device->max_speed = device->card->link_speed;
555
556                 while (device->max_speed > SCODE_100) {
557                         if (read_rom(device, generation, 0, &dummy) ==
558                             RCODE_COMPLETE)
559                                 break;
560                         device->max_speed--;
561                 }
562         }
563
564         /*
565          * Now parse the config rom.  The config rom is a recursive
566          * directory structure so we parse it using a stack of
567          * references to the blocks that make up the structure.  We
568          * push a reference to the root directory on the stack to
569          * start things off.
570          */
571         length = i;
572         sp = 0;
573         stack[sp++] = 0xc0000005;
574         while (sp > 0) {
575                 /*
576                  * Pop the next block reference of the stack.  The
577                  * lower 24 bits is the offset into the config rom,
578                  * the upper 8 bits are the type of the reference the
579                  * block.
580                  */
581                 key = stack[--sp];
582                 i = key & 0xffffff;
583                 if (WARN_ON(i >= MAX_CONFIG_ROM_SIZE))
584                         goto out;
585
586                 /* Read header quadlet for the block to get the length. */
587                 if (read_rom(device, generation, i, &rom[i]) != RCODE_COMPLETE)
588                         goto out;
589                 end = i + (rom[i] >> 16) + 1;
590                 if (end > MAX_CONFIG_ROM_SIZE) {
591                         /*
592                          * This block extends outside the config ROM which is
593                          * a firmware bug.  Ignore this whole block, i.e.
594                          * simply set a fake block length of 0.
595                          */
596                         fw_error("skipped invalid ROM block %x at %llx\n",
597                                  rom[i],
598                                  i * 4 | CSR_REGISTER_BASE | CSR_CONFIG_ROM);
599                         rom[i] = 0;
600                         end = i;
601                 }
602                 i++;
603
604                 /*
605                  * Now read in the block.  If this is a directory
606                  * block, check the entries as we read them to see if
607                  * it references another block, and push it in that case.
608                  */
609                 for (; i < end; i++) {
610                         if (read_rom(device, generation, i, &rom[i]) !=
611                             RCODE_COMPLETE)
612                                 goto out;
613
614                         if ((key >> 30) != 3 || (rom[i] >> 30) < 2)
615                                 continue;
616                         /*
617                          * Offset points outside the ROM.  May be a firmware
618                          * bug or an Extended ROM entry (IEEE 1212-2001 clause
619                          * 7.7.18).  Simply overwrite this pointer here by a
620                          * fake immediate entry so that later iterators over
621                          * the ROM don't have to check offsets all the time.
622                          */
623                         if (i + (rom[i] & 0xffffff) >= MAX_CONFIG_ROM_SIZE) {
624                                 fw_error("skipped unsupported ROM entry %x at %llx\n",
625                                          rom[i],
626                                          i * 4 | CSR_REGISTER_BASE | CSR_CONFIG_ROM);
627                                 rom[i] = 0;
628                                 continue;
629                         }
630                         stack[sp++] = i + rom[i];
631                 }
632                 if (length < i)
633                         length = i;
634         }
635
636         old_rom = device->config_rom;
637         new_rom = kmemdup(rom, length * 4, GFP_KERNEL);
638         if (new_rom == NULL)
639                 goto out;
640
641         down_write(&fw_device_rwsem);
642         device->config_rom = new_rom;
643         device->config_rom_length = length;
644         up_write(&fw_device_rwsem);
645
646         kfree(old_rom);
647         ret = 0;
648         device->max_rec = rom[2] >> 12 & 0xf;
649         device->cmc     = rom[2] >> 30 & 1;
650         device->irmc    = rom[2] >> 31 & 1;
651  out:
652         kfree(rom);
653
654         return ret;
655 }
656
657 static void fw_unit_release(struct device *dev)
658 {
659         struct fw_unit *unit = fw_unit(dev);
660
661         kfree(unit);
662 }
663
664 static struct device_type fw_unit_type = {
665         .uevent         = fw_unit_uevent,
666         .release        = fw_unit_release,
667 };
668
669 static bool is_fw_unit(struct device *dev)
670 {
671         return dev->type == &fw_unit_type;
672 }
673
674 static void create_units(struct fw_device *device)
675 {
676         struct fw_csr_iterator ci;
677         struct fw_unit *unit;
678         int key, value, i;
679
680         i = 0;
681         fw_csr_iterator_init(&ci, &device->config_rom[5]);
682         while (fw_csr_iterator_next(&ci, &key, &value)) {
683                 if (key != (CSR_UNIT | CSR_DIRECTORY))
684                         continue;
685
686                 /*
687                  * Get the address of the unit directory and try to
688                  * match the drivers id_tables against it.
689                  */
690                 unit = kzalloc(sizeof(*unit), GFP_KERNEL);
691                 if (unit == NULL) {
692                         fw_error("failed to allocate memory for unit\n");
693                         continue;
694                 }
695
696                 unit->directory = ci.p + value - 1;
697                 unit->device.bus = &fw_bus_type;
698                 unit->device.type = &fw_unit_type;
699                 unit->device.parent = &device->device;
700                 dev_set_name(&unit->device, "%s.%d", dev_name(&device->device), i++);
701
702                 BUILD_BUG_ON(ARRAY_SIZE(unit->attribute_group.attrs) <
703                                 ARRAY_SIZE(fw_unit_attributes) +
704                                 ARRAY_SIZE(config_rom_attributes));
705                 init_fw_attribute_group(&unit->device,
706                                         fw_unit_attributes,
707                                         &unit->attribute_group);
708
709                 if (device_register(&unit->device) < 0)
710                         goto skip_unit;
711
712                 continue;
713
714         skip_unit:
715                 kfree(unit);
716         }
717 }
718
719 static int shutdown_unit(struct device *device, void *data)
720 {
721         device_unregister(device);
722
723         return 0;
724 }
725
726 /*
727  * fw_device_rwsem acts as dual purpose mutex:
728  *   - serializes accesses to fw_device_idr,
729  *   - serializes accesses to fw_device.config_rom/.config_rom_length and
730  *     fw_unit.directory, unless those accesses happen at safe occasions
731  */
732 DECLARE_RWSEM(fw_device_rwsem);
733
734 DEFINE_IDR(fw_device_idr);
735 int fw_cdev_major;
736
737 struct fw_device *fw_device_get_by_devt(dev_t devt)
738 {
739         struct fw_device *device;
740
741         down_read(&fw_device_rwsem);
742         device = idr_find(&fw_device_idr, MINOR(devt));
743         if (device)
744                 fw_device_get(device);
745         up_read(&fw_device_rwsem);
746
747         return device;
748 }
749
750 /*
751  * These defines control the retry behavior for reading the config
752  * rom.  It shouldn't be necessary to tweak these; if the device
753  * doesn't respond to a config rom read within 10 seconds, it's not
754  * going to respond at all.  As for the initial delay, a lot of
755  * devices will be able to respond within half a second after bus
756  * reset.  On the other hand, it's not really worth being more
757  * aggressive than that, since it scales pretty well; if 10 devices
758  * are plugged in, they're all getting read within one second.
759  */
760
761 #define MAX_RETRIES     10
762 #define RETRY_DELAY     (3 * HZ)
763 #define INITIAL_DELAY   (HZ / 2)
764 #define SHUTDOWN_DELAY  (2 * HZ)
765
766 static void fw_device_shutdown(struct work_struct *work)
767 {
768         struct fw_device *device =
769                 container_of(work, struct fw_device, work.work);
770         int minor = MINOR(device->device.devt);
771
772         if (time_is_after_jiffies(device->card->reset_jiffies + SHUTDOWN_DELAY)
773             && !list_empty(&device->card->link)) {
774                 schedule_delayed_work(&device->work, SHUTDOWN_DELAY);
775                 return;
776         }
777
778         if (atomic_cmpxchg(&device->state,
779                            FW_DEVICE_GONE,
780                            FW_DEVICE_SHUTDOWN) != FW_DEVICE_GONE)
781                 return;
782
783         fw_device_cdev_remove(device);
784         device_for_each_child(&device->device, NULL, shutdown_unit);
785         device_unregister(&device->device);
786
787         down_write(&fw_device_rwsem);
788         idr_remove(&fw_device_idr, minor);
789         up_write(&fw_device_rwsem);
790
791         fw_device_put(device);
792 }
793
794 static void fw_device_release(struct device *dev)
795 {
796         struct fw_device *device = fw_device(dev);
797         struct fw_card *card = device->card;
798         unsigned long flags;
799
800         /*
801          * Take the card lock so we don't set this to NULL while a
802          * FW_NODE_UPDATED callback is being handled or while the
803          * bus manager work looks at this node.
804          */
805         spin_lock_irqsave(&card->lock, flags);
806         device->node->data = NULL;
807         spin_unlock_irqrestore(&card->lock, flags);
808
809         fw_node_put(device->node);
810         kfree(device->config_rom);
811         kfree(device);
812         fw_card_put(card);
813 }
814
815 static struct device_type fw_device_type = {
816         .release = fw_device_release,
817 };
818
819 static bool is_fw_device(struct device *dev)
820 {
821         return dev->type == &fw_device_type;
822 }
823
824 static int update_unit(struct device *dev, void *data)
825 {
826         struct fw_unit *unit = fw_unit(dev);
827         struct fw_driver *driver = (struct fw_driver *)dev->driver;
828
829         if (is_fw_unit(dev) && driver != NULL && driver->update != NULL) {
830                 device_lock(dev);
831                 driver->update(unit);
832                 device_unlock(dev);
833         }
834
835         return 0;
836 }
837
838 static void fw_device_update(struct work_struct *work)
839 {
840         struct fw_device *device =
841                 container_of(work, struct fw_device, work.work);
842
843         fw_device_cdev_update(device);
844         device_for_each_child(&device->device, NULL, update_unit);
845 }
846
847 /*
848  * If a device was pending for deletion because its node went away but its
849  * bus info block and root directory header matches that of a newly discovered
850  * device, revive the existing fw_device.
851  * The newly allocated fw_device becomes obsolete instead.
852  */
853 static int lookup_existing_device(struct device *dev, void *data)
854 {
855         struct fw_device *old = fw_device(dev);
856         struct fw_device *new = data;
857         struct fw_card *card = new->card;
858         int match = 0;
859
860         if (!is_fw_device(dev))
861                 return 0;
862
863         down_read(&fw_device_rwsem); /* serialize config_rom access */
864         spin_lock_irq(&card->lock);  /* serialize node access */
865
866         if (memcmp(old->config_rom, new->config_rom, 6 * 4) == 0 &&
867             atomic_cmpxchg(&old->state,
868                            FW_DEVICE_GONE,
869                            FW_DEVICE_RUNNING) == FW_DEVICE_GONE) {
870                 struct fw_node *current_node = new->node;
871                 struct fw_node *obsolete_node = old->node;
872
873                 new->node = obsolete_node;
874                 new->node->data = new;
875                 old->node = current_node;
876                 old->node->data = old;
877
878                 old->max_speed = new->max_speed;
879                 old->node_id = current_node->node_id;
880                 smp_wmb();  /* update node_id before generation */
881                 old->generation = card->generation;
882                 old->config_rom_retries = 0;
883                 fw_notify("rediscovered device %s\n", dev_name(dev));
884
885                 PREPARE_DELAYED_WORK(&old->work, fw_device_update);
886                 schedule_delayed_work(&old->work, 0);
887
888                 if (current_node == card->root_node)
889                         fw_schedule_bm_work(card, 0);
890
891                 match = 1;
892         }
893
894         spin_unlock_irq(&card->lock);
895         up_read(&fw_device_rwsem);
896
897         return match;
898 }
899
900 enum { BC_UNKNOWN = 0, BC_UNIMPLEMENTED, BC_IMPLEMENTED, };
901
902 static void set_broadcast_channel(struct fw_device *device, int generation)
903 {
904         struct fw_card *card = device->card;
905         __be32 data;
906         int rcode;
907
908         if (!card->broadcast_channel_allocated)
909                 return;
910
911         /*
912          * The Broadcast_Channel Valid bit is required by nodes which want to
913          * transmit on this channel.  Such transmissions are practically
914          * exclusive to IP over 1394 (RFC 2734).  IP capable nodes are required
915          * to be IRM capable and have a max_rec of 8 or more.  We use this fact
916          * to narrow down to which nodes we send Broadcast_Channel updates.
917          */
918         if (!device->irmc || device->max_rec < 8)
919                 return;
920
921         /*
922          * Some 1394-1995 nodes crash if this 1394a-2000 register is written.
923          * Perform a read test first.
924          */
925         if (device->bc_implemented == BC_UNKNOWN) {
926                 rcode = fw_run_transaction(card, TCODE_READ_QUADLET_REQUEST,
927                                 device->node_id, generation, device->max_speed,
928                                 CSR_REGISTER_BASE + CSR_BROADCAST_CHANNEL,
929                                 &data, 4);
930                 switch (rcode) {
931                 case RCODE_COMPLETE:
932                         if (data & cpu_to_be32(1 << 31)) {
933                                 device->bc_implemented = BC_IMPLEMENTED;
934                                 break;
935                         }
936                         /* else fall through to case address error */
937                 case RCODE_ADDRESS_ERROR:
938                         device->bc_implemented = BC_UNIMPLEMENTED;
939                 }
940         }
941
942         if (device->bc_implemented == BC_IMPLEMENTED) {
943                 data = cpu_to_be32(BROADCAST_CHANNEL_INITIAL |
944                                    BROADCAST_CHANNEL_VALID);
945                 fw_run_transaction(card, TCODE_WRITE_QUADLET_REQUEST,
946                                 device->node_id, generation, device->max_speed,
947                                 CSR_REGISTER_BASE + CSR_BROADCAST_CHANNEL,
948                                 &data, 4);
949         }
950 }
951
952 int fw_device_set_broadcast_channel(struct device *dev, void *gen)
953 {
954         if (is_fw_device(dev))
955                 set_broadcast_channel(fw_device(dev), (long)gen);
956
957         return 0;
958 }
959
960 static void fw_device_init(struct work_struct *work)
961 {
962         struct fw_device *device =
963                 container_of(work, struct fw_device, work.work);
964         struct device *revived_dev;
965         int minor, ret;
966
967         /*
968          * All failure paths here set node->data to NULL, so that we
969          * don't try to do device_for_each_child() on a kfree()'d
970          * device.
971          */
972
973         if (read_config_rom(device, device->generation) < 0) {
974                 if (device->config_rom_retries < MAX_RETRIES &&
975                     atomic_read(&device->state) == FW_DEVICE_INITIALIZING) {
976                         device->config_rom_retries++;
977                         schedule_delayed_work(&device->work, RETRY_DELAY);
978                 } else {
979                         fw_notify("giving up on config rom for node id %x\n",
980                                   device->node_id);
981                         if (device->node == device->card->root_node)
982                                 fw_schedule_bm_work(device->card, 0);
983                         fw_device_release(&device->device);
984                 }
985                 return;
986         }
987
988         revived_dev = device_find_child(device->card->device,
989                                         device, lookup_existing_device);
990         if (revived_dev) {
991                 put_device(revived_dev);
992                 fw_device_release(&device->device);
993
994                 return;
995         }
996
997         device_initialize(&device->device);
998
999         fw_device_get(device);
1000         down_write(&fw_device_rwsem);
1001         ret = idr_pre_get(&fw_device_idr, GFP_KERNEL) ?
1002               idr_get_new(&fw_device_idr, device, &minor) :
1003               -ENOMEM;
1004         up_write(&fw_device_rwsem);
1005
1006         if (ret < 0)
1007                 goto error;
1008
1009         device->device.bus = &fw_bus_type;
1010         device->device.type = &fw_device_type;
1011         device->device.parent = device->card->device;
1012         device->device.devt = MKDEV(fw_cdev_major, minor);
1013         dev_set_name(&device->device, "fw%d", minor);
1014
1015         BUILD_BUG_ON(ARRAY_SIZE(device->attribute_group.attrs) <
1016                         ARRAY_SIZE(fw_device_attributes) +
1017                         ARRAY_SIZE(config_rom_attributes));
1018         init_fw_attribute_group(&device->device,
1019                                 fw_device_attributes,
1020                                 &device->attribute_group);
1021
1022         if (device_add(&device->device)) {
1023                 fw_error("Failed to add device.\n");
1024                 goto error_with_cdev;
1025         }
1026
1027         create_units(device);
1028
1029         /*
1030          * Transition the device to running state.  If it got pulled
1031          * out from under us while we did the intialization work, we
1032          * have to shut down the device again here.  Normally, though,
1033          * fw_node_event will be responsible for shutting it down when
1034          * necessary.  We have to use the atomic cmpxchg here to avoid
1035          * racing with the FW_NODE_DESTROYED case in
1036          * fw_node_event().
1037          */
1038         if (atomic_cmpxchg(&device->state,
1039                            FW_DEVICE_INITIALIZING,
1040                            FW_DEVICE_RUNNING) == FW_DEVICE_GONE) {
1041                 PREPARE_DELAYED_WORK(&device->work, fw_device_shutdown);
1042                 schedule_delayed_work(&device->work, SHUTDOWN_DELAY);
1043         } else {
1044                 if (device->config_rom_retries)
1045                         fw_notify("created device %s: GUID %08x%08x, S%d00, "
1046                                   "%d config ROM retries\n",
1047                                   dev_name(&device->device),
1048                                   device->config_rom[3], device->config_rom[4],
1049                                   1 << device->max_speed,
1050                                   device->config_rom_retries);
1051                 else
1052                         fw_notify("created device %s: GUID %08x%08x, S%d00\n",
1053                                   dev_name(&device->device),
1054                                   device->config_rom[3], device->config_rom[4],
1055                                   1 << device->max_speed);
1056                 device->config_rom_retries = 0;
1057
1058                 set_broadcast_channel(device, device->generation);
1059         }
1060
1061         /*
1062          * Reschedule the IRM work if we just finished reading the
1063          * root node config rom.  If this races with a bus reset we
1064          * just end up running the IRM work a couple of extra times -
1065          * pretty harmless.
1066          */
1067         if (device->node == device->card->root_node)
1068                 fw_schedule_bm_work(device->card, 0);
1069
1070         return;
1071
1072  error_with_cdev:
1073         down_write(&fw_device_rwsem);
1074         idr_remove(&fw_device_idr, minor);
1075         up_write(&fw_device_rwsem);
1076  error:
1077         fw_device_put(device);          /* fw_device_idr's reference */
1078
1079         put_device(&device->device);    /* our reference */
1080 }
1081
1082 enum {
1083         REREAD_BIB_ERROR,
1084         REREAD_BIB_GONE,
1085         REREAD_BIB_UNCHANGED,
1086         REREAD_BIB_CHANGED,
1087 };
1088
1089 /* Reread and compare bus info block and header of root directory */
1090 static int reread_config_rom(struct fw_device *device, int generation)
1091 {
1092         u32 q;
1093         int i;
1094
1095         for (i = 0; i < 6; i++) {
1096                 if (read_rom(device, generation, i, &q) != RCODE_COMPLETE)
1097                         return REREAD_BIB_ERROR;
1098
1099                 if (i == 0 && q == 0)
1100                         return REREAD_BIB_GONE;
1101
1102                 if (q != device->config_rom[i])
1103                         return REREAD_BIB_CHANGED;
1104         }
1105
1106         return REREAD_BIB_UNCHANGED;
1107 }
1108
1109 static void fw_device_refresh(struct work_struct *work)
1110 {
1111         struct fw_device *device =
1112                 container_of(work, struct fw_device, work.work);
1113         struct fw_card *card = device->card;
1114         int node_id = device->node_id;
1115
1116         switch (reread_config_rom(device, device->generation)) {
1117         case REREAD_BIB_ERROR:
1118                 if (device->config_rom_retries < MAX_RETRIES / 2 &&
1119                     atomic_read(&device->state) == FW_DEVICE_INITIALIZING) {
1120                         device->config_rom_retries++;
1121                         schedule_delayed_work(&device->work, RETRY_DELAY / 2);
1122
1123                         return;
1124                 }
1125                 goto give_up;
1126
1127         case REREAD_BIB_GONE:
1128                 goto gone;
1129
1130         case REREAD_BIB_UNCHANGED:
1131                 if (atomic_cmpxchg(&device->state,
1132                                    FW_DEVICE_INITIALIZING,
1133                                    FW_DEVICE_RUNNING) == FW_DEVICE_GONE)
1134                         goto gone;
1135
1136                 fw_device_update(work);
1137                 device->config_rom_retries = 0;
1138                 goto out;
1139
1140         case REREAD_BIB_CHANGED:
1141                 break;
1142         }
1143
1144         /*
1145          * Something changed.  We keep things simple and don't investigate
1146          * further.  We just destroy all previous units and create new ones.
1147          */
1148         device_for_each_child(&device->device, NULL, shutdown_unit);
1149
1150         if (read_config_rom(device, device->generation) < 0) {
1151                 if (device->config_rom_retries < MAX_RETRIES &&
1152                     atomic_read(&device->state) == FW_DEVICE_INITIALIZING) {
1153                         device->config_rom_retries++;
1154                         schedule_delayed_work(&device->work, RETRY_DELAY);
1155
1156                         return;
1157                 }
1158                 goto give_up;
1159         }
1160
1161         create_units(device);
1162
1163         /* Userspace may want to re-read attributes. */
1164         kobject_uevent(&device->device.kobj, KOBJ_CHANGE);
1165
1166         if (atomic_cmpxchg(&device->state,
1167                            FW_DEVICE_INITIALIZING,
1168                            FW_DEVICE_RUNNING) == FW_DEVICE_GONE)
1169                 goto gone;
1170
1171         fw_notify("refreshed device %s\n", dev_name(&device->device));
1172         device->config_rom_retries = 0;
1173         goto out;
1174
1175  give_up:
1176         fw_notify("giving up on refresh of device %s\n", dev_name(&device->device));
1177  gone:
1178         atomic_set(&device->state, FW_DEVICE_GONE);
1179         PREPARE_DELAYED_WORK(&device->work, fw_device_shutdown);
1180         schedule_delayed_work(&device->work, SHUTDOWN_DELAY);
1181  out:
1182         if (node_id == card->root_node->node_id)
1183                 fw_schedule_bm_work(card, 0);
1184 }
1185
1186 void fw_node_event(struct fw_card *card, struct fw_node *node, int event)
1187 {
1188         struct fw_device *device;
1189
1190         switch (event) {
1191         case FW_NODE_CREATED:
1192         case FW_NODE_LINK_ON:
1193                 if (!node->link_on)
1194                         break;
1195  create:
1196                 device = kzalloc(sizeof(*device), GFP_ATOMIC);
1197                 if (device == NULL)
1198                         break;
1199
1200                 /*
1201                  * Do minimal intialization of the device here, the
1202                  * rest will happen in fw_device_init().
1203                  *
1204                  * Attention:  A lot of things, even fw_device_get(),
1205                  * cannot be done before fw_device_init() finished!
1206                  * You can basically just check device->state and
1207                  * schedule work until then, but only while holding
1208                  * card->lock.
1209                  */
1210                 atomic_set(&device->state, FW_DEVICE_INITIALIZING);
1211                 device->card = fw_card_get(card);
1212                 device->node = fw_node_get(node);
1213                 device->node_id = node->node_id;
1214                 device->generation = card->generation;
1215                 device->is_local = node == card->local_node;
1216                 mutex_init(&device->client_list_mutex);
1217                 INIT_LIST_HEAD(&device->client_list);
1218
1219                 /*
1220                  * Set the node data to point back to this device so
1221                  * FW_NODE_UPDATED callbacks can update the node_id
1222                  * and generation for the device.
1223                  */
1224                 node->data = device;
1225
1226                 /*
1227                  * Many devices are slow to respond after bus resets,
1228                  * especially if they are bus powered and go through
1229                  * power-up after getting plugged in.  We schedule the
1230                  * first config rom scan half a second after bus reset.
1231                  */
1232                 INIT_DELAYED_WORK(&device->work, fw_device_init);
1233                 schedule_delayed_work(&device->work, INITIAL_DELAY);
1234                 break;
1235
1236         case FW_NODE_INITIATED_RESET:
1237                 device = node->data;
1238                 if (device == NULL)
1239                         goto create;
1240
1241                 device->node_id = node->node_id;
1242                 smp_wmb();  /* update node_id before generation */
1243                 device->generation = card->generation;
1244                 if (atomic_cmpxchg(&device->state,
1245                             FW_DEVICE_RUNNING,
1246                             FW_DEVICE_INITIALIZING) == FW_DEVICE_RUNNING) {
1247                         PREPARE_DELAYED_WORK(&device->work, fw_device_refresh);
1248                         schedule_delayed_work(&device->work,
1249                                 device->is_local ? 0 : INITIAL_DELAY);
1250                 }
1251                 break;
1252
1253         case FW_NODE_UPDATED:
1254                 if (!node->link_on || node->data == NULL)
1255                         break;
1256
1257                 device = node->data;
1258                 device->node_id = node->node_id;
1259                 smp_wmb();  /* update node_id before generation */
1260                 device->generation = card->generation;
1261                 if (atomic_read(&device->state) == FW_DEVICE_RUNNING) {
1262                         PREPARE_DELAYED_WORK(&device->work, fw_device_update);
1263                         schedule_delayed_work(&device->work, 0);
1264                 }
1265                 break;
1266
1267         case FW_NODE_DESTROYED:
1268         case FW_NODE_LINK_OFF:
1269                 if (!node->data)
1270                         break;
1271
1272                 /*
1273                  * Destroy the device associated with the node.  There
1274                  * are two cases here: either the device is fully
1275                  * initialized (FW_DEVICE_RUNNING) or we're in the
1276                  * process of reading its config rom
1277                  * (FW_DEVICE_INITIALIZING).  If it is fully
1278                  * initialized we can reuse device->work to schedule a
1279                  * full fw_device_shutdown().  If not, there's work
1280                  * scheduled to read it's config rom, and we just put
1281                  * the device in shutdown state to have that code fail
1282                  * to create the device.
1283                  */
1284                 device = node->data;
1285                 if (atomic_xchg(&device->state,
1286                                 FW_DEVICE_GONE) == FW_DEVICE_RUNNING) {
1287                         PREPARE_DELAYED_WORK(&device->work, fw_device_shutdown);
1288                         schedule_delayed_work(&device->work,
1289                                 list_empty(&card->link) ? 0 : SHUTDOWN_DELAY);
1290                 }
1291                 break;
1292         }
1293 }