aboutsummaryrefslogtreecommitdiff
path: root/drivers/firewire/fw-device.c
blob: 2af5a8d1e012112ceacd08c69b50ae2c3fc202ea (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
/*
 * Device probing and sysfs code.
 *
 * Copyright (C) 2005-2006  Kristian Hoegsberg <krh@bitplanet.net>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software Foundation,
 * Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
 */

#include <linux/module.h>
#include <linux/wait.h>
#include <linux/errno.h>
#include <linux/kthread.h>
#include <linux/device.h>
#include <linux/delay.h>
#include <linux/idr.h>
#include <linux/string.h>
#include <linux/rwsem.h>
#include <linux/semaphore.h>
#include <asm/system.h>
#include <linux/ctype.h>
#include "fw-transaction.h"
#include "fw-topology.h"
#include "fw-device.h"

void fw_csr_iterator_init(struct fw_csr_iterator *ci, u32 * p)
{
	ci->p = p + 1;
	ci->end = ci->p + (p[0] >> 16);
}
EXPORT_SYMBOL(fw_csr_iterator_init);

int fw_csr_iterator_next(struct fw_csr_iterator *ci, int *key, int *value)
{
	*key = *ci->p >> 24;
	*value = *ci->p & 0xffffff;

	return ci->p++ < ci->end;
}
EXPORT_SYMBOL(fw_csr_iterator_next);

static int is_fw_unit(struct device *dev);

static int match_unit_directory(u32 * directory, const struct fw_device_id *id)
{
	struct fw_csr_iterator ci;
	int key, value, match;

	match = 0;
	fw_csr_iterator_init(&ci, directory);
	while (fw_csr_iterator_next(&ci, &key, &value)) {
		if (key == CSR_VENDOR && value == id->vendor)
			match |= FW_MATCH_VENDOR;
		if (key == CSR_MODEL && value == id->model)
			match |= FW_MATCH_MODEL;
		if (key == CSR_SPECIFIER_ID && value == id->specifier_id)
			match |= FW_MATCH_SPECIFIER_ID;
		if (key == CSR_VERSION && value == id->version)
			match |= FW_MATCH_VERSION;
	}

	return (match & id->match_flags) == id->match_flags;
}

static int fw_unit_match(struct device *dev, struct device_driver *drv)
{
	struct fw_unit *unit = fw_unit(dev);
	struct fw_driver *driver = fw_driver(drv);
	int i;

	/* We only allow binding to fw_units. */
	if (!is_fw_unit(dev))
		return 0;

	for (i = 0; driver->id_table[i].match_flags != 0; i++) {
		if (match_unit_directory(unit->directory, &driver->id_table[i]))
			return 1;
	}

	return 0;
}

static int get_modalias(struct fw_unit *unit, char *buffer, size_t buffer_size)
{
	struct fw_device *device = fw_device(unit->device.parent);
	struct fw_csr_iterator ci;

	int key, value;
	int vendor = 0;
	int model = 0;
	int specifier_id = 0;
	int version = 0;

	fw_csr_iterator_init(&ci, &device->config_rom[5]);
	while (fw_csr_iterator_next(&ci, &key, &value)) {
		switch (key) {
		case CSR_VENDOR:
			vendor = value;
			break;
		case CSR_MODEL:
			model = value;
			break;
		}
	}

	fw_csr_iterator_init(&ci, unit->directory);
	while (fw_csr_iterator_next(&ci, &key, &value)) {
		switch (key) {
		case CSR_SPECIFIER_ID:
			specifier_id = value;
			break;
		case CSR_VERSION:
			version = value;
			break;
		}
	}

	return snprintf(buffer, buffer_size,
			"ieee1394:ven%08Xmo%08Xsp%08Xver%08X",
			vendor, model, specifier_id, version);
}

static int
fw_unit_uevent(struct device *dev, struct kobj_uevent_env *env)
{
	struct fw_unit *unit = fw_unit(dev);
	char modalias[64];

	get_modalias(unit, modalias, sizeof(modalias));

	if (add_uevent_var(env, "MODALIAS=%s", modalias))
		return -ENOMEM;

	return 0;
}

struct bus_type fw_bus_type = {
	.name = "firewire",
	.match = fw_unit_match,
};
EXPORT_SYMBOL(fw_bus_type);

static void fw_device_release(struct device *dev)
{
	struct fw_device *device = fw_device(dev);
	struct fw_card *card = device->card;
	unsigned long flags;

	/*
	 * Take the card lock so we don't set this to NULL while a
	 * FW_NODE_UPDATED callback is being handled or while the
	 * bus manager work looks at this node.
	 */
	spin_lock_irqsave(&card->lock, flags);
	device->node->data = NULL;
	spin_unlock_irqrestore(&card->lock, flags);

	fw_node_put(device->node);
	kfree(device->config_rom);
	kfree(device);
	fw_card_put(card);
}

int fw_device_enable_phys_dma(struct fw_device *device)
{
	int generation = device->generation;

	/* device->node_id, accessed below, must not be older than generation */
	smp_rmb();

	return device->card->driver->enable_phys_dma(device->card,
						     device->node_id,
						     generation);
}
EXPORT_SYMBOL(fw_device_enable_phys_dma);

struct config_rom_attribute {
	struct device_attribute attr;
	u32 key;
};

static ssize_t
show_immediate(struct device *dev, struct device_attribute *dattr, char *buf)
{
	struct config_rom_attribute *attr =
		container_of(dattr, struct config_rom_attribute, attr);
	struct fw_csr_iterator ci;
	u32 *dir;
	int key, value, ret = -ENOENT;

	down_read(&fw_device_rwsem);

	if (is_fw_unit(dev))
		dir = fw_unit(dev)->directory;
	else
		dir = fw_device(dev)->config_rom + 5;

	fw_csr_iterator_init(&ci, dir);
	while (fw_csr_iterator_next(&ci, &key, &value))
		if (attr->key == key) {
			ret = snprintf(buf, buf ? PAGE_SIZE : 0,
				       "0x%06x\n", value);
			break;
		}

	up_read(&fw_device_rwsem);

	return ret;
}

#define IMMEDIATE_ATTR(name, key)				\
	{ __ATTR(name, S_IRUGO, show_immediate, NULL), key }

static ssize_t
show_text_leaf(struct device *dev, struct device_attribute *dattr, char *buf)
{
	struct config_rom_attribute *attr =
		container_of(dattr, struct config_rom_attribute, attr);
	struct fw_csr_iterator ci;
	u32 *dir, *block = NULL, *p, *end;
	int length, key, value, last_key = 0, ret = -ENOENT;
	char *b;

	down_read(&fw_device_rwsem);

	if (is_fw_unit(dev))
		dir = fw_unit(dev)->directory;
	else
		dir = fw_device(dev)->config_rom + 5;

	fw_csr_iterator_init(&ci, dir);
	while (fw_csr_iterator_next(&ci, &key, &value)) {
		if (attr->key == last_key &&
		    key == (CSR_DESCRIPTOR | CSR_LEAF))
			block = ci.p - 1 + value;
		last_key = key;
	}

	if (block == NULL)
		goto out;

	length = min(block[0] >> 16, 256U);
	if (length < 3)
		goto out;

	if (block[1] != 0 || block[2] != 0)
		/* Unknown encoding. */
		goto out;

	if (buf == NULL) {
		ret = length * 4;
		goto out;
	}

	b = buf;
	end = &block[length + 1];
	for (p = &block[3]; p < end; p++, b += 4)
		* (u32 *) b = (__force u32) __cpu_to_be32(*p);

	/* Strip trailing whitespace and add newline. */
	while (b--, (isspace(*b) || *b == '\0') && b > buf);
	strcpy(b + 1, "\n");
	ret = b + 2 - buf;
 out:
	up_read(&fw_device_rwsem);

	return ret;
}

#define TEXT_LEAF_ATTR(name, key)				\
	{ __ATTR(name, S_IRUGO, show_text_leaf, NULL), key }

static struct config_rom_attribute config_rom_attributes[] = {
	IMMEDIATE_ATTR(vendor, CSR_VENDOR),
	IMMEDIATE_ATTR(hardware_version, CSR_HARDWARE_VERSION),
	IMMEDIATE_ATTR(specifier_id, CSR_SPECIFIER_ID),
	IMMEDIATE_ATTR(version, CSR_VERSION),
	IMMEDIATE_ATTR(model, CSR_MODEL),
	TEXT_LEAF_ATTR(vendor_name, CSR_VENDOR),
	TEXT_LEAF_ATTR(model_name, CSR_MODEL),
	TEXT_LEAF_ATTR(hardware_version_name, CSR_HARDWARE_VERSION),
};

static void
init_fw_attribute_group(struct device *dev,
			struct device_attribute *attrs,
			struct fw_attribute_group *group)
{
	struct device_attribute *attr;
	int i, j;

	for (j = 0; attrs[j].attr.name != NULL; j++)
		group->attrs[j] = &attrs[j].attr;

	for (i = 0; i < ARRAY_SIZE(config_rom_attributes); i++) {
		attr = &config_rom_attributes[i].attr;
		if (attr->show(dev, attr, NULL) < 0)
			continue;
		group->attrs[j++] = &attr->attr;
	}

	BUG_ON(j >= ARRAY_SIZE(group->attrs));
	group->attrs[j++] = NULL;
	group->groups[0] = &group->group;
	group->groups[1] = NULL;
	group->group.attrs = group->attrs;
	dev->groups = group->groups;
}

static ssize_t
modalias_show(struct device *dev,
	      struct device_attribute *attr, char *buf)
{
	struct fw_unit *unit = fw_unit(dev);
	int length;

	length = get_modalias(unit, buf, PAGE_SIZE);
	strcpy(buf + length, "\n");

	return length + 1;
}

static ssize_t
rom_index_show(struct device *dev,
	       struct device_attribute *attr, char *buf)
{
	struct fw_device *device = fw_device(dev->parent);
	struct fw_unit *unit = fw_unit(dev);

	return snprintf(buf, PAGE_SIZE, "%d\n",
			(int)(unit->directory - device->config_rom));
}

static struct device_attribute fw_unit_attributes[] = {
	__ATTR_RO(modalias),
	__ATTR_RO(rom_index),
	__ATTR_NULL,
};

static ssize_t
config_rom_show(struct device *dev, struct device_attribute *attr, char *buf)
{
	struct fw_device *device = fw_device(dev);
	size_t length;

	down_read(&fw_device_rwsem);
	length = device->config_rom_length * 4;
	memcpy(buf, device->config_rom, length);
	up_read(&fw_device_rwsem);

	return length;
}

static ssize_t
guid_show(struct device *dev, struct device_attribute *attr, char *buf)
{
	struct fw_device *device = fw_device(dev);
	int ret;

	down_read(&fw_device_rwsem);
	ret = snprintf(buf, PAGE_SIZE, "0x%08x%08x\n",
		       device->config_rom[3], device->config_rom[4]);
	up_read(&fw_device_rwsem);

	return ret;
}

static struct device_attribute fw_device_attributes[] = {
	__ATTR_RO(config_rom),
	__ATTR_RO(guid),
	__ATTR_NULL,
};

static int
read_rom(struct fw_device *device, int generation, int index, u32 *data)
{
	int rcode;

	/* device->node_id, accessed below, must not be older than generation */
	smp_rmb();

	rcode = fw_run_transaction(device->card, TCODE_READ_QUADLET_REQUEST,
			device->node_id, generation, device->max_speed,
			(CSR_REGISTER_BASE | CSR_CONFIG_ROM) + index * 4,
			data, 4);
	be32_to_cpus(data);

	return rcode;
}

#define READ_BIB_ROM_SIZE	256
#define READ_BIB_STACK_SIZE	16

/*
 * Read the bus info block, perform a speed probe, and read all of the rest of
 * the config ROM.  We do all this with a cached bus generation.  If the bus
 * generation changes under us, read_bus_info_block will fail and get retried.
 * It's better to start all over in this case because the node from which we
 * are reading the ROM may have changed the ROM during the reset.
 */
static int read_bus_info_block(struct fw_device *device, int generation)
{
	u32 *rom, *stack, *old_rom, *new_rom;
	u32 sp, key;
	int i, end, length, ret = -1;

	rom = kmalloc(sizeof(*rom) * READ_BIB_ROM_SIZE +
		      sizeof(*stack) * READ_BIB_STACK_SIZE, GFP_KERNEL);
	if (rom == NULL)
		return -ENOMEM;

	stack = &rom[READ_BIB_ROM_SIZE];

	device->max_speed = SCODE_100;

	/* First read the bus info block. */
	for (i = 0; i < 5; i++) {
		if (read_rom(device, generation, i, &rom[i]) != RCODE_COMPLETE)
			goto out;
		/*
		 * As per IEEE1212 7.2, during power-up, devices can
		 * reply with a 0 for the first quadlet of the config
		 * rom to indicate that they are booting (for example,
		 * if the firmware is on the disk of a external
		 * harddisk).  In that case we just fail, and the
		 * retry mechanism will try again later.
		 */
		if (i == 0 && rom[i] == 0)
			goto out;
	}

	device->max_speed = device->node->max_speed;

	/*
	 * Determine the speed of
	 *   - devices with link speed less than PHY speed,
	 *   - devices with 1394b PHY (unless only connected to 1394a PHYs),
	 *   - all devices if there are 1394b repeaters.
	 * Note, we cannot use the bus info block's link_spd as starting point
	 * because some buggy firmwares set it lower than necessary and because
	 * 1394-1995 nodes do not have the field.
	 */
	if ((rom[2] & 0x7) < device->max_speed ||
	    device->max_speed == SCODE_BETA ||
	    device->card->beta_repeaters_present) {
		u32 dummy;

		/* for S1600 and S3200 */
		if (device->max_speed == SCODE_BETA)
			device->max_speed = device->card->link_speed;

		while (device->max_speed > SCODE_100) {
			if (read_rom(device, generation, 0, &dummy) ==
			    RCODE_COMPLETE)
				break;
			device->max_speed--;
		}
	}

	/*
	 * Now parse the config rom.  The config rom is a recursive
	 * directory structure so we parse it using a stack of
	 * references to the blocks that make up the structure.  We
	 * push a reference to the root directory on the stack to
	 * start things off.
	 */
	length = i;
	sp = 0;
	stack[sp++] = 0xc0000005;
	while (sp > 0) {
		/*
		 * Pop the next block reference of the stack.  The
		 * lower 24 bits is the offset into the config rom,
		 * the upper 8 bits are the type of the reference the
		 * block.
		 */
		key = stack[--sp];
		i = key & 0xffffff;
		if (i >= READ_BIB_ROM_SIZE)
			/*
			 * The reference points outside the standard
			 * config rom area, something's fishy.
			 */
			goto out;

		/* Read header quadlet for the block to get the length. */
		if (read_rom(device, generation, i, &rom[i]) != RCODE_COMPLETE)
			goto out;
		end = i + (rom[i] >> 16) + 1;
		i++;
		if (end > READ_BIB_ROM_SIZE)
			/*
			 * This block extends outside standard config
			 * area (and the array we're reading it
			 * into).  That's broken, so ignore this
			 * device.
			 */
			goto out;

		/*
		 * Now read in the block.  If this is a directory
		 * block, check the entries as we read them to see if
		 * it references another block, and push it in that case.
		 */
		while (i < end) {
			if (read_rom(device, generation, i, &rom[i]) !=
			    RCODE_COMPLETE)
				goto out;
			if ((key >> 30) == 3 && (rom[i] >> 30) > 1 &&
			    sp < READ_BIB_STACK_SIZE)
				stack[sp++] = i + rom[i];
			i++;
		}
		if (length < i)
			length = i;
	}

	old_rom = device->config_rom;
	new_rom = kmemdup(rom, length * 4, GFP_KERNEL);
	if (new_rom == NULL)
		goto out;

	down_write(&fw_device_rwsem);
	device->config_rom = new_rom;
	device->config_rom_length = length;
	up_write(&fw_device_rwsem);

	kfree(old_rom);
	ret = 0;
	device->cmc = rom[2] & 1 << 30;
 out:
	kfree(rom);

	return ret;
}

static void fw_unit_release(struct device *dev)
{
	struct fw_unit *unit = fw_unit(dev);

	kfree(unit);
}

static struct device_type fw_unit_type = {
	.uevent		= fw_unit_uevent,
	.release	= fw_unit_release,
};

static int is_fw_unit(struct device *dev)
{
	return dev->type == &fw_unit_type;
}

static void create_units(struct fw_device *device)
{
	struct fw_csr_iterator ci;
	struct fw_unit *unit;
	int key, value, i;

	i = 0;
	fw_csr_iterator_init(&ci, &device->config_rom[5]);
	while (fw_csr_iterator_next(&ci, &key, &value)) {
		if (key != (CSR_UNIT | CSR_DIRECTORY))
			continue;

		/*
		 * Get the address of the unit directory and try to
		 * match the drivers id_tables against it.
		 */
		unit = kzalloc(sizeof(*unit), GFP_KERNEL);
		if (unit == NULL) {
			fw_error("failed to allocate memory for unit\n");
			continue;
		}

		unit->directory = ci.p + value - 1;
		unit->device.bus = &fw_bus_type;
		unit->device.type = &fw_unit_type;
		unit->device.parent = &device->device;
		dev_set_name(&unit->device, "%s.%d", dev_name(&device->device), i++);

		init_fw_attribute_group(&unit->device,
					fw_unit_attributes,
					&unit->attribute_group);
		if (device_register(&unit->device) < 0)
			goto skip_unit;

		continue;

	skip_unit:
		kfree(unit);
	}
}

static int shutdown_unit(struct device *device, void *data)
{
	device_unregister(device);

	return 0;
}

/*
 * fw_device_rwsem acts as dual purpose mutex:
 *   - serializes accesses to fw_device_idr,
 *   - serializes accesses to fw_device.config_rom/.config_rom_length and
 *     fw_unit.directory, unless those accesses happen at safe occasions
 */
DECLARE_RWSEM(fw_device_rwsem);

DEFINE_IDR(fw_device_idr);
int fw_cdev_major;

struct fw_device *fw_device_get_by_devt(dev_t devt)
{
	struct fw_device *device;

	down_read(&fw_device_rwsem);
	device = idr_find(&fw_device_idr, MINOR(devt));
	if (device)
		fw_device_get(device);
	up_read(&fw_device_rwsem);

	return device;
}

static void fw_device_shutdown(struct work_struct *work)
{
	struct fw_device *device =
		container_of(work, struct fw_device, work.work);
	int minor = MINOR(device->device.devt);

	fw_device_cdev_remove(device);
	device_for_each_child(&device->device, NULL, shutdown_unit);
	device_unregister(&device->device);

	down_write(&fw_device_rwsem);
	idr_remove(&fw_device_idr, minor);
	up_write(&fw_device_rwsem);
	fw_device_put(device);
}

static struct device_type fw_device_type = {
	.release	= fw_device_release,
};

/*
 * These defines control the retry behavior for reading the config
 * rom.  It shouldn't be necessary to tweak these; if the device
 * doesn't respond to a config rom read within 10 seconds, it's not
 * going to respond at all.  As for the initial delay, a lot of
 * devices will be able to respond within half a second after bus
 * reset.  On the other hand, it's not really worth being more
 * aggressive than that, since it scales pretty well; if 10 devices
 * are plugged in, they're all getting read within one second.
 */

#define MAX_RETRIES	10
#define RETRY_DELAY	(3 * HZ)
#define INITIAL_DELAY	(HZ / 2)

static void fw_device_init(struct work_struct *work)
{
	struct fw_device *device =
		container_of(work, struct fw_device, work.work);
	int minor, err;

	/*
	 * All failure paths here set node->data to NULL, so that we
	 * don't try to do device_for_each_child() on a kfree()'d
	 * device.
	 */

	if (read_bus_info_block(device, device->generation) < 0) {
		if (device->config_rom_retries < MAX_RETRIES &&
		    atomic_read(&device->state) == FW_DEVICE_INITIALIZING) {
			device->config_rom_retries++;
			schedule_delayed_work(&device->work, RETRY_DELAY);
		} else {
			fw_notify("giving up on config rom for node id %x\n",
				  device->node_id);
			if (device->node == device->card->root_node)
				fw_schedule_bm_work(device->card, 0);
			fw_device_release(&device->device);
		}
		return;
	}

	device_initialize(&device->device);

	fw_device_get(device);
	down_write(&fw_device_rwsem);
	err = idr_pre_get(&fw_device_idr, GFP_KERNEL) ?
	      idr_get_new(&fw_device_idr, device, &minor) :
	      -ENOMEM;
	up_write(&fw_device_rwsem);

	if (err < 0)
		goto error;

	device->device.bus = &fw_bus_type;
	device->device.type = &fw_device_type;
	device->device.parent = device->card->device;
	device->device.devt = MKDEV(fw_cdev_major, minor);
	dev_set_name(&device->device, "fw%d", minor);

	init_fw_attribute_group(&device->device,
				fw_device_attributes,
				&device->attribute_group);
	if (device_add(&device->device)) {
		fw_error("Failed to add device.\n");
		goto error_with_cdev;
	}

	create_units(device);

	/*
	 * Transition the device to running state.  If it got pulled
	 * out from under us while we did the intialization work, we
	 * have to shut down the device again here.  Normally, though,
	 * fw_node_event will be responsible for shutting it down when
	 * necessary.  We have to use the atomic cmpxchg here to avoid
	 * racing with the FW_NODE_DESTROYED case in
	 * fw_node_event().
	 */
	if (atomic_cmpxchg(&device->state,
		    FW_DEVICE_INITIALIZING,
		    FW_DEVICE_RUNNING) == FW_DEVICE_SHUTDOWN) {
		fw_device_shutdown(work);
	} else {
		if (device->config_rom_retries)
			fw_notify("created device %s: GUID %08x%08x, S%d00, "
				  "%d config ROM retries\n",
				  dev_name(&device->device),
				  device->config_rom[3], device->config_rom[4],
				  1 << device->max_speed,
				  device->config_rom_retries);
		else
			fw_notify("created device %s: GUID %08x%08x, S%d00\n",
				  dev_name(&device->device),
				  device->config_rom[3], device->config_rom[4],
				  1 << device->max_speed);
		device->config_rom_retries = 0;
	}

	/*
	 * Reschedule the IRM work if we just finished reading the
	 * root node config rom.  If this races with a bus reset we
	 * just end up running the IRM work a couple of extra times -
	 * pretty harmless.
	 */
	if (device->node == device->card->root_node)
		fw_schedule_bm_work(device->card, 0);

	return;

 error_with_cdev:
	down_write(&fw_device_rwsem);
	idr_remove(&fw_device_idr, minor);
	up_write(&fw_device_rwsem);
 error:
	fw_device_put(device);		/* fw_device_idr's reference */

	put_device(&device->device);	/* our reference */
}

static int update_unit(struct device *dev, void *data)
{
	struct fw_unit *unit = fw_unit(dev);
	struct fw_driver *driver = (struct fw_driver *)dev->driver;

	if (is_fw_unit(dev) && driver != NULL && driver->update != NULL) {
		down(&dev->sem);
		driver->update(unit);
		up(&dev->sem);
	}

	return 0;
}

static void fw_device_update(struct work_struct *work)
{
	struct fw_device *device =
		container_of(work, struct fw_device, work.work);

	fw_device_cdev_update(device);
	device_for_each_child(&device->device, NULL, update_unit);
}

enum {
	REREAD_BIB_ERROR,
	REREAD_BIB_GONE,
	REREAD_BIB_UNCHANGED,
	REREAD_BIB_CHANGED,
};

/* Reread and compare bus info block and header of root directory */
static int reread_bus_info_block(struct fw_device *device, int generation)
{
	u32 q;
	int i;

	for (i = 0; i < 6; i++) {
		if (read_rom(device, generation, i, &q) != RCODE_COMPLETE)
			return REREAD_BIB_ERROR;

		if (i == 0 && q == 0)
			return REREAD_BIB_GONE;

		if (i > device->config_rom_length || q != device->config_rom[i])
			return REREAD_BIB_CHANGED;
	}

	return REREAD_BIB_UNCHANGED;
}

static void fw_device_refresh(struct work_struct *work)
{
	struct fw_device *device =
		container_of(work, struct fw_device, work.work);
	struct fw_card *card = device->card;
	int node_id = device->node_id;

	switch (reread_bus_info_block(device, device->generation)) {
	case REREAD_BIB_ERROR:
		if (device->config_rom_retries < MAX_RETRIES / 2 &&
		    atomic_read(&device->state) == FW_DEVICE_INITIALIZING) {
			device->config_rom_retries++;
			schedule_delayed_work(&device->work, RETRY_DELAY / 2);

			return;
		}
		goto give_up;

	case REREAD_BIB_GONE:
		goto gone;

	case REREAD_BIB_UNCHANGED:
		if (atomic_cmpxchg(&device->state,
			    FW_DEVICE_INITIALIZING,
			    FW_DEVICE_RUNNING) == FW_DEVICE_SHUTDOWN)
			goto gone;

		fw_device_update(work);
		device->config_rom_retries = 0;
		goto out;

	case REREAD_BIB_CHANGED:
		break;
	}

	/*
	 * Something changed.  We keep things simple and don't investigate
	 * further.  We just destroy all previous units and create new ones.
	 */
	device_for_each_child(&device->device, NULL, shutdown_unit);

	if (read_bus_info_block(device, device->generation) < 0) {
		if (device->config_rom_retries < MAX_RETRIES &&
		    atomic_read(&device->state) == FW_DEVICE_INITIALIZING) {
			device->config_rom_retries++;
			schedule_delayed_work(&device->work, RETRY_DELAY);

			return;
		}
		goto give_up;
	}

	create_units(device);

	if (atomic_cmpxchg(&device->state,
		    FW_DEVICE_INITIALIZING,
		    FW_DEVICE_RUNNING) == FW_DEVICE_SHUTDOWN)
		goto gone;

	fw_notify("refreshed device %s\n", dev_name(&device->device));
	device->config_rom_retries = 0;
	goto out;

 give_up:
	fw_notify("giving up on refresh of device %s\n", dev_name(&device->device));
 gone:
	atomic_set(&device->state, FW_DEVICE_SHUTDOWN);
	fw_device_shutdown(work);
 out:
	if (node_id == card->root_node->node_id)
		fw_schedule_bm_work(card, 0);
}

void fw_node_event(struct fw_card *card, struct fw_node *node, int event)
{
	struct fw_device *device;

	switch (event) {
	case FW_NODE_CREATED:
	case FW_NODE_LINK_ON:
		if (!node->link_on)
			break;
 create:
		device = kzalloc(sizeof(*device), GFP_ATOMIC);
		if (device == NULL)
			break;

		/*
		 * Do minimal intialization of the device here, the
		 * rest will happen in fw_device_init().
		 *
		 * Attention:  A lot of things, even fw_device_get(),
		 * cannot be done before fw_device_init() finished!
		 * You can basically just check device->state and
		 * schedule work until then, but only while holding
		 * card->lock.
		 */
		atomic_set(&device->state, FW_DEVICE_INITIALIZING);
		device->card = fw_card_get(card);
		device->node = fw_node_get(node);
		device->node_id = node->node_id;
		device->generation = card->generation;
		INIT_LIST_HEAD(&device->client_list);

		/*
		 * Set the node data to point back to this device so
		 * FW_NODE_UPDATED callbacks can update the node_id
		 * and generation for the device.
		 */
		node->data = device;

		/*
		 * Many devices are slow to respond after bus resets,
		 * especially if they are bus powered and go through
		 * power-up after getting plugged in.  We schedule the
		 * first config rom scan half a second after bus reset.
		 */
		INIT_DELAYED_WORK(&device->work, fw_device_init);
		schedule_delayed_work(&device->work, INITIAL_DELAY);
		break;

	case FW_NODE_INITIATED_RESET:
		device = node->data;
		if (device == NULL)
			goto create;

		device->node_id = node->node_id;
		smp_wmb();  /* update node_id before generation */
		device->generation = card->generation;
		if (atomic_cmpxchg(&device->state,
			    FW_DEVICE_RUNNING,
			    FW_DEVICE_INITIALIZING) == FW_DEVICE_RUNNING) {
			PREPARE_DELAYED_WORK(&device->work, fw_device_refresh);
			schedule_delayed_work(&device->work,
				node == card->local_node ? 0 : INITIAL_DELAY);
		}
		break;

	case FW_NODE_UPDATED:
		if (!node->link_on || node->data == NULL)
			break;

		device = node->data;
		device->node_id = node->node_id;
		smp_wmb();  /* update node_id before generation */
		device->generation = card->generation;
		if (atomic_read(&device->state) == FW_DEVICE_RUNNING) {
			PREPARE_DELAYED_WORK(&device->work, fw_device_update);
			schedule_delayed_work(&device->work, 0);
		}
		break;

	case FW_NODE_DESTROYED:
	case FW_NODE_LINK_OFF:
		if (!node->data)
			break;

		/*
		 * Destroy the device associated with the node.  There
		 * are two cases here: either the device is fully
		 * initialized (FW_DEVICE_RUNNING) or we're in the
		 * process of reading its config rom
		 * (FW_DEVICE_INITIALIZING).  If it is fully
		 * initialized we can reuse device->work to schedule a
		 * full fw_device_shutdown().  If not, there's work
		 * scheduled to read it's config rom, and we just put
		 * the device in shutdown state to have that code fail
		 * to create the device.
		 */
		device = node->data;
		if (atomic_xchg(&device->state,
				FW_DEVICE_SHUTDOWN) == FW_DEVICE_RUNNING) {
			PREPARE_DELAYED_WORK(&device->work, fw_device_shutdown);
			schedule_delayed_work(&device->work, 0);
		}
		break;
	}
}