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/random.h>
36 #include <linux/rwsem.h>
37 #include <linux/slab.h>
38 #include <linux/spinlock.h>
39 #include <linux/string.h>
40 #include <linux/workqueue.h>
41 
42 #include <linux/atomic.h>
43 #include <asm/byteorder.h>
44 
45 #include "core.h"
46 
47 void fw_csr_iterator_init(struct fw_csr_iterator *ci, const u32 *p)
48 {
49 	ci->p = p + 1;
50 	ci->end = ci->p + (p[0] >> 16);
51 }
52 EXPORT_SYMBOL(fw_csr_iterator_init);
53 
54 int fw_csr_iterator_next(struct fw_csr_iterator *ci, int *key, int *value)
55 {
56 	*key = *ci->p >> 24;
57 	*value = *ci->p & 0xffffff;
58 
59 	return ci->p++ < ci->end;
60 }
61 EXPORT_SYMBOL(fw_csr_iterator_next);
62 
63 static const u32 *search_leaf(const u32 *directory, int search_key)
64 {
65 	struct fw_csr_iterator ci;
66 	int last_key = 0, key, value;
67 
68 	fw_csr_iterator_init(&ci, directory);
69 	while (fw_csr_iterator_next(&ci, &key, &value)) {
70 		if (last_key == search_key &&
71 		    key == (CSR_DESCRIPTOR | CSR_LEAF))
72 			return ci.p - 1 + value;
73 
74 		last_key = key;
75 	}
76 
77 	return NULL;
78 }
79 
80 static int textual_leaf_to_string(const u32 *block, char *buf, size_t size)
81 {
82 	unsigned int quadlets, i;
83 	char c;
84 
85 	if (!size || !buf)
86 		return -EINVAL;
87 
88 	quadlets = min(block[0] >> 16, 256U);
89 	if (quadlets < 2)
90 		return -ENODATA;
91 
92 	if (block[1] != 0 || block[2] != 0)
93 		/* unknown language/character set */
94 		return -ENODATA;
95 
96 	block += 3;
97 	quadlets -= 2;
98 	for (i = 0; i < quadlets * 4 && i < size - 1; i++) {
99 		c = block[i / 4] >> (24 - 8 * (i % 4));
100 		if (c == '\0')
101 			break;
102 		buf[i] = c;
103 	}
104 	buf[i] = '\0';
105 
106 	return i;
107 }
108 
109 /**
110  * fw_csr_string() - reads a string from the configuration ROM
111  * @directory:	e.g. root directory or unit directory
112  * @key:	the key of the preceding directory entry
113  * @buf:	where to put the string
114  * @size:	size of @buf, in bytes
115  *
116  * The string is taken from a minimal ASCII text descriptor leaf after
117  * the immediate entry with @key.  The string is zero-terminated.
118  * An overlong string is silently truncated such that it and the
119  * zero byte fit into @size.
120  *
121  * Returns strlen(buf) or a negative error code.
122  */
123 int fw_csr_string(const u32 *directory, int key, char *buf, size_t size)
124 {
125 	const u32 *leaf = search_leaf(directory, key);
126 	if (!leaf)
127 		return -ENOENT;
128 
129 	return textual_leaf_to_string(leaf, buf, size);
130 }
131 EXPORT_SYMBOL(fw_csr_string);
132 
133 static void get_ids(const u32 *directory, int *id)
134 {
135 	struct fw_csr_iterator ci;
136 	int key, value;
137 
138 	fw_csr_iterator_init(&ci, directory);
139 	while (fw_csr_iterator_next(&ci, &key, &value)) {
140 		switch (key) {
141 		case CSR_VENDOR:	id[0] = value; break;
142 		case CSR_MODEL:		id[1] = value; break;
143 		case CSR_SPECIFIER_ID:	id[2] = value; break;
144 		case CSR_VERSION:	id[3] = value; break;
145 		}
146 	}
147 }
148 
149 static void get_modalias_ids(struct fw_unit *unit, int *id)
150 {
151 	get_ids(&fw_parent_device(unit)->config_rom[5], id);
152 	get_ids(unit->directory, id);
153 }
154 
155 static bool match_ids(const struct ieee1394_device_id *id_table, int *id)
156 {
157 	int match = 0;
158 
159 	if (id[0] == id_table->vendor_id)
160 		match |= IEEE1394_MATCH_VENDOR_ID;
161 	if (id[1] == id_table->model_id)
162 		match |= IEEE1394_MATCH_MODEL_ID;
163 	if (id[2] == id_table->specifier_id)
164 		match |= IEEE1394_MATCH_SPECIFIER_ID;
165 	if (id[3] == id_table->version)
166 		match |= IEEE1394_MATCH_VERSION;
167 
168 	return (match & id_table->match_flags) == id_table->match_flags;
169 }
170 
171 static const struct ieee1394_device_id *unit_match(struct device *dev,
172 						   struct device_driver *drv)
173 {
174 	const struct ieee1394_device_id *id_table =
175 			container_of(drv, struct fw_driver, driver)->id_table;
176 	int id[] = {0, 0, 0, 0};
177 
178 	get_modalias_ids(fw_unit(dev), id);
179 
180 	for (; id_table->match_flags != 0; id_table++)
181 		if (match_ids(id_table, id))
182 			return id_table;
183 
184 	return NULL;
185 }
186 
187 static bool is_fw_unit(struct device *dev);
188 
189 static int fw_unit_match(struct device *dev, struct device_driver *drv)
190 {
191 	/* We only allow binding to fw_units. */
192 	return is_fw_unit(dev) && unit_match(dev, drv) != NULL;
193 }
194 
195 static int fw_unit_probe(struct device *dev)
196 {
197 	struct fw_driver *driver =
198 			container_of(dev->driver, struct fw_driver, driver);
199 
200 	return driver->probe(fw_unit(dev), unit_match(dev, dev->driver));
201 }
202 
203 static int fw_unit_remove(struct device *dev)
204 {
205 	struct fw_driver *driver =
206 			container_of(dev->driver, struct fw_driver, driver);
207 
208 	return driver->remove(fw_unit(dev)), 0;
209 }
210 
211 static int get_modalias(struct fw_unit *unit, char *buffer, size_t buffer_size)
212 {
213 	int id[] = {0, 0, 0, 0};
214 
215 	get_modalias_ids(unit, id);
216 
217 	return snprintf(buffer, buffer_size,
218 			"ieee1394:ven%08Xmo%08Xsp%08Xver%08X",
219 			id[0], id[1], id[2], id[3]);
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 	.probe = fw_unit_probe,
239 	.remove = fw_unit_remove,
240 };
241 EXPORT_SYMBOL(fw_bus_type);
242 
243 int fw_device_enable_phys_dma(struct fw_device *device)
244 {
245 	int generation = device->generation;
246 
247 	/* device->node_id, accessed below, must not be older than generation */
248 	smp_rmb();
249 
250 	return device->card->driver->enable_phys_dma(device->card,
251 						     device->node_id,
252 						     generation);
253 }
254 EXPORT_SYMBOL(fw_device_enable_phys_dma);
255 
256 struct config_rom_attribute {
257 	struct device_attribute attr;
258 	u32 key;
259 };
260 
261 static ssize_t show_immediate(struct device *dev,
262 			      struct device_attribute *dattr, char *buf)
263 {
264 	struct config_rom_attribute *attr =
265 		container_of(dattr, struct config_rom_attribute, attr);
266 	struct fw_csr_iterator ci;
267 	const u32 *dir;
268 	int key, value, ret = -ENOENT;
269 
270 	down_read(&fw_device_rwsem);
271 
272 	if (is_fw_unit(dev))
273 		dir = fw_unit(dev)->directory;
274 	else
275 		dir = fw_device(dev)->config_rom + 5;
276 
277 	fw_csr_iterator_init(&ci, dir);
278 	while (fw_csr_iterator_next(&ci, &key, &value))
279 		if (attr->key == key) {
280 			ret = snprintf(buf, buf ? PAGE_SIZE : 0,
281 				       "0x%06x\n", value);
282 			break;
283 		}
284 
285 	up_read(&fw_device_rwsem);
286 
287 	return ret;
288 }
289 
290 #define IMMEDIATE_ATTR(name, key)				\
291 	{ __ATTR(name, S_IRUGO, show_immediate, NULL), key }
292 
293 static ssize_t show_text_leaf(struct device *dev,
294 			      struct device_attribute *dattr, char *buf)
295 {
296 	struct config_rom_attribute *attr =
297 		container_of(dattr, struct config_rom_attribute, attr);
298 	const u32 *dir;
299 	size_t bufsize;
300 	char dummy_buf[2];
301 	int ret;
302 
303 	down_read(&fw_device_rwsem);
304 
305 	if (is_fw_unit(dev))
306 		dir = fw_unit(dev)->directory;
307 	else
308 		dir = fw_device(dev)->config_rom + 5;
309 
310 	if (buf) {
311 		bufsize = PAGE_SIZE - 1;
312 	} else {
313 		buf = dummy_buf;
314 		bufsize = 1;
315 	}
316 
317 	ret = fw_csr_string(dir, attr->key, buf, bufsize);
318 
319 	if (ret >= 0) {
320 		/* Strip trailing whitespace and add newline. */
321 		while (ret > 0 && isspace(buf[ret - 1]))
322 			ret--;
323 		strcpy(buf + ret, "\n");
324 		ret++;
325 	}
326 
327 	up_read(&fw_device_rwsem);
328 
329 	return ret;
330 }
331 
332 #define TEXT_LEAF_ATTR(name, key)				\
333 	{ __ATTR(name, S_IRUGO, show_text_leaf, NULL), key }
334 
335 static struct config_rom_attribute config_rom_attributes[] = {
336 	IMMEDIATE_ATTR(vendor, CSR_VENDOR),
337 	IMMEDIATE_ATTR(hardware_version, CSR_HARDWARE_VERSION),
338 	IMMEDIATE_ATTR(specifier_id, CSR_SPECIFIER_ID),
339 	IMMEDIATE_ATTR(version, CSR_VERSION),
340 	IMMEDIATE_ATTR(model, CSR_MODEL),
341 	TEXT_LEAF_ATTR(vendor_name, CSR_VENDOR),
342 	TEXT_LEAF_ATTR(model_name, CSR_MODEL),
343 	TEXT_LEAF_ATTR(hardware_version_name, CSR_HARDWARE_VERSION),
344 };
345 
346 static void init_fw_attribute_group(struct device *dev,
347 				    struct device_attribute *attrs,
348 				    struct fw_attribute_group *group)
349 {
350 	struct device_attribute *attr;
351 	int i, j;
352 
353 	for (j = 0; attrs[j].attr.name != NULL; j++)
354 		group->attrs[j] = &attrs[j].attr;
355 
356 	for (i = 0; i < ARRAY_SIZE(config_rom_attributes); i++) {
357 		attr = &config_rom_attributes[i].attr;
358 		if (attr->show(dev, attr, NULL) < 0)
359 			continue;
360 		group->attrs[j++] = &attr->attr;
361 	}
362 
363 	group->attrs[j] = NULL;
364 	group->groups[0] = &group->group;
365 	group->groups[1] = NULL;
366 	group->group.attrs = group->attrs;
367 	dev->groups = (const struct attribute_group **) group->groups;
368 }
369 
370 static ssize_t modalias_show(struct device *dev,
371 			     struct device_attribute *attr, char *buf)
372 {
373 	struct fw_unit *unit = fw_unit(dev);
374 	int length;
375 
376 	length = get_modalias(unit, buf, PAGE_SIZE);
377 	strcpy(buf + length, "\n");
378 
379 	return length + 1;
380 }
381 
382 static ssize_t rom_index_show(struct device *dev,
383 			      struct device_attribute *attr, char *buf)
384 {
385 	struct fw_device *device = fw_device(dev->parent);
386 	struct fw_unit *unit = fw_unit(dev);
387 
388 	return snprintf(buf, PAGE_SIZE, "%d\n",
389 			(int)(unit->directory - device->config_rom));
390 }
391 
392 static struct device_attribute fw_unit_attributes[] = {
393 	__ATTR_RO(modalias),
394 	__ATTR_RO(rom_index),
395 	__ATTR_NULL,
396 };
397 
398 static ssize_t config_rom_show(struct device *dev,
399 			       struct device_attribute *attr, char *buf)
400 {
401 	struct fw_device *device = fw_device(dev);
402 	size_t length;
403 
404 	down_read(&fw_device_rwsem);
405 	length = device->config_rom_length * 4;
406 	memcpy(buf, device->config_rom, length);
407 	up_read(&fw_device_rwsem);
408 
409 	return length;
410 }
411 
412 static ssize_t guid_show(struct device *dev,
413 			 struct device_attribute *attr, char *buf)
414 {
415 	struct fw_device *device = fw_device(dev);
416 	int ret;
417 
418 	down_read(&fw_device_rwsem);
419 	ret = snprintf(buf, PAGE_SIZE, "0x%08x%08x\n",
420 		       device->config_rom[3], device->config_rom[4]);
421 	up_read(&fw_device_rwsem);
422 
423 	return ret;
424 }
425 
426 static ssize_t is_local_show(struct device *dev,
427 			     struct device_attribute *attr, char *buf)
428 {
429 	struct fw_device *device = fw_device(dev);
430 
431 	return sprintf(buf, "%u\n", device->is_local);
432 }
433 
434 static int units_sprintf(char *buf, const u32 *directory)
435 {
436 	struct fw_csr_iterator ci;
437 	int key, value;
438 	int specifier_id = 0;
439 	int version = 0;
440 
441 	fw_csr_iterator_init(&ci, directory);
442 	while (fw_csr_iterator_next(&ci, &key, &value)) {
443 		switch (key) {
444 		case CSR_SPECIFIER_ID:
445 			specifier_id = value;
446 			break;
447 		case CSR_VERSION:
448 			version = value;
449 			break;
450 		}
451 	}
452 
453 	return sprintf(buf, "0x%06x:0x%06x ", specifier_id, version);
454 }
455 
456 static ssize_t units_show(struct device *dev,
457 			  struct device_attribute *attr, char *buf)
458 {
459 	struct fw_device *device = fw_device(dev);
460 	struct fw_csr_iterator ci;
461 	int key, value, i = 0;
462 
463 	down_read(&fw_device_rwsem);
464 	fw_csr_iterator_init(&ci, &device->config_rom[5]);
465 	while (fw_csr_iterator_next(&ci, &key, &value)) {
466 		if (key != (CSR_UNIT | CSR_DIRECTORY))
467 			continue;
468 		i += units_sprintf(&buf[i], ci.p + value - 1);
469 		if (i >= PAGE_SIZE - (8 + 1 + 8 + 1))
470 			break;
471 	}
472 	up_read(&fw_device_rwsem);
473 
474 	if (i)
475 		buf[i - 1] = '\n';
476 
477 	return i;
478 }
479 
480 static struct device_attribute fw_device_attributes[] = {
481 	__ATTR_RO(config_rom),
482 	__ATTR_RO(guid),
483 	__ATTR_RO(is_local),
484 	__ATTR_RO(units),
485 	__ATTR_NULL,
486 };
487 
488 static int read_rom(struct fw_device *device,
489 		    int generation, int index, u32 *data)
490 {
491 	u64 offset = (CSR_REGISTER_BASE | CSR_CONFIG_ROM) + index * 4;
492 	int i, rcode;
493 
494 	/* device->node_id, accessed below, must not be older than generation */
495 	smp_rmb();
496 
497 	for (i = 10; i < 100; i += 10) {
498 		rcode = fw_run_transaction(device->card,
499 				TCODE_READ_QUADLET_REQUEST, device->node_id,
500 				generation, device->max_speed, offset, data, 4);
501 		if (rcode != RCODE_BUSY)
502 			break;
503 		msleep(i);
504 	}
505 	be32_to_cpus(data);
506 
507 	return rcode;
508 }
509 
510 #define MAX_CONFIG_ROM_SIZE 256
511 
512 /*
513  * Read the bus info block, perform a speed probe, and read all of the rest of
514  * the config ROM.  We do all this with a cached bus generation.  If the bus
515  * generation changes under us, read_config_rom will fail and get retried.
516  * It's better to start all over in this case because the node from which we
517  * are reading the ROM may have changed the ROM during the reset.
518  * Returns either a result code or a negative error code.
519  */
520 static int read_config_rom(struct fw_device *device, int generation)
521 {
522 	struct fw_card *card = device->card;
523 	const u32 *old_rom, *new_rom;
524 	u32 *rom, *stack;
525 	u32 sp, key;
526 	int i, end, length, ret;
527 
528 	rom = kmalloc(sizeof(*rom) * MAX_CONFIG_ROM_SIZE +
529 		      sizeof(*stack) * MAX_CONFIG_ROM_SIZE, GFP_KERNEL);
530 	if (rom == NULL)
531 		return -ENOMEM;
532 
533 	stack = &rom[MAX_CONFIG_ROM_SIZE];
534 	memset(rom, 0, sizeof(*rom) * MAX_CONFIG_ROM_SIZE);
535 
536 	device->max_speed = SCODE_100;
537 
538 	/* First read the bus info block. */
539 	for (i = 0; i < 5; i++) {
540 		ret = read_rom(device, generation, i, &rom[i]);
541 		if (ret != RCODE_COMPLETE)
542 			goto out;
543 		/*
544 		 * As per IEEE1212 7.2, during initialization, devices can
545 		 * reply with a 0 for the first quadlet of the config
546 		 * rom to indicate that they are booting (for example,
547 		 * if the firmware is on the disk of a external
548 		 * harddisk).  In that case we just fail, and the
549 		 * retry mechanism will try again later.
550 		 */
551 		if (i == 0 && rom[i] == 0) {
552 			ret = RCODE_BUSY;
553 			goto out;
554 		}
555 	}
556 
557 	device->max_speed = device->node->max_speed;
558 
559 	/*
560 	 * Determine the speed of
561 	 *   - devices with link speed less than PHY speed,
562 	 *   - devices with 1394b PHY (unless only connected to 1394a PHYs),
563 	 *   - all devices if there are 1394b repeaters.
564 	 * Note, we cannot use the bus info block's link_spd as starting point
565 	 * because some buggy firmwares set it lower than necessary and because
566 	 * 1394-1995 nodes do not have the field.
567 	 */
568 	if ((rom[2] & 0x7) < device->max_speed ||
569 	    device->max_speed == SCODE_BETA ||
570 	    card->beta_repeaters_present) {
571 		u32 dummy;
572 
573 		/* for S1600 and S3200 */
574 		if (device->max_speed == SCODE_BETA)
575 			device->max_speed = card->link_speed;
576 
577 		while (device->max_speed > SCODE_100) {
578 			if (read_rom(device, generation, 0, &dummy) ==
579 			    RCODE_COMPLETE)
580 				break;
581 			device->max_speed--;
582 		}
583 	}
584 
585 	/*
586 	 * Now parse the config rom.  The config rom is a recursive
587 	 * directory structure so we parse it using a stack of
588 	 * references to the blocks that make up the structure.  We
589 	 * push a reference to the root directory on the stack to
590 	 * start things off.
591 	 */
592 	length = i;
593 	sp = 0;
594 	stack[sp++] = 0xc0000005;
595 	while (sp > 0) {
596 		/*
597 		 * Pop the next block reference of the stack.  The
598 		 * lower 24 bits is the offset into the config rom,
599 		 * the upper 8 bits are the type of the reference the
600 		 * block.
601 		 */
602 		key = stack[--sp];
603 		i = key & 0xffffff;
604 		if (WARN_ON(i >= MAX_CONFIG_ROM_SIZE)) {
605 			ret = -ENXIO;
606 			goto out;
607 		}
608 
609 		/* Read header quadlet for the block to get the length. */
610 		ret = read_rom(device, generation, i, &rom[i]);
611 		if (ret != RCODE_COMPLETE)
612 			goto out;
613 		end = i + (rom[i] >> 16) + 1;
614 		if (end > MAX_CONFIG_ROM_SIZE) {
615 			/*
616 			 * This block extends outside the config ROM which is
617 			 * a firmware bug.  Ignore this whole block, i.e.
618 			 * simply set a fake block length of 0.
619 			 */
620 			fw_err(card, "skipped invalid ROM block %x at %llx\n",
621 			       rom[i],
622 			       i * 4 | CSR_REGISTER_BASE | CSR_CONFIG_ROM);
623 			rom[i] = 0;
624 			end = i;
625 		}
626 		i++;
627 
628 		/*
629 		 * Now read in the block.  If this is a directory
630 		 * block, check the entries as we read them to see if
631 		 * it references another block, and push it in that case.
632 		 */
633 		for (; i < end; i++) {
634 			ret = read_rom(device, generation, i, &rom[i]);
635 			if (ret != RCODE_COMPLETE)
636 				goto out;
637 
638 			if ((key >> 30) != 3 || (rom[i] >> 30) < 2)
639 				continue;
640 			/*
641 			 * Offset points outside the ROM.  May be a firmware
642 			 * bug or an Extended ROM entry (IEEE 1212-2001 clause
643 			 * 7.7.18).  Simply overwrite this pointer here by a
644 			 * fake immediate entry so that later iterators over
645 			 * the ROM don't have to check offsets all the time.
646 			 */
647 			if (i + (rom[i] & 0xffffff) >= MAX_CONFIG_ROM_SIZE) {
648 				fw_err(card,
649 				       "skipped unsupported ROM entry %x at %llx\n",
650 				       rom[i],
651 				       i * 4 | CSR_REGISTER_BASE | CSR_CONFIG_ROM);
652 				rom[i] = 0;
653 				continue;
654 			}
655 			stack[sp++] = i + rom[i];
656 		}
657 		if (length < i)
658 			length = i;
659 	}
660 
661 	old_rom = device->config_rom;
662 	new_rom = kmemdup(rom, length * 4, GFP_KERNEL);
663 	if (new_rom == NULL) {
664 		ret = -ENOMEM;
665 		goto out;
666 	}
667 
668 	down_write(&fw_device_rwsem);
669 	device->config_rom = new_rom;
670 	device->config_rom_length = length;
671 	up_write(&fw_device_rwsem);
672 
673 	kfree(old_rom);
674 	ret = RCODE_COMPLETE;
675 	device->max_rec	= rom[2] >> 12 & 0xf;
676 	device->cmc	= rom[2] >> 30 & 1;
677 	device->irmc	= rom[2] >> 31 & 1;
678  out:
679 	kfree(rom);
680 
681 	return ret;
682 }
683 
684 static void fw_unit_release(struct device *dev)
685 {
686 	struct fw_unit *unit = fw_unit(dev);
687 
688 	fw_device_put(fw_parent_device(unit));
689 	kfree(unit);
690 }
691 
692 static struct device_type fw_unit_type = {
693 	.uevent		= fw_unit_uevent,
694 	.release	= fw_unit_release,
695 };
696 
697 static bool is_fw_unit(struct device *dev)
698 {
699 	return dev->type == &fw_unit_type;
700 }
701 
702 static void create_units(struct fw_device *device)
703 {
704 	struct fw_csr_iterator ci;
705 	struct fw_unit *unit;
706 	int key, value, i;
707 
708 	i = 0;
709 	fw_csr_iterator_init(&ci, &device->config_rom[5]);
710 	while (fw_csr_iterator_next(&ci, &key, &value)) {
711 		if (key != (CSR_UNIT | CSR_DIRECTORY))
712 			continue;
713 
714 		/*
715 		 * Get the address of the unit directory and try to
716 		 * match the drivers id_tables against it.
717 		 */
718 		unit = kzalloc(sizeof(*unit), GFP_KERNEL);
719 		if (unit == NULL)
720 			continue;
721 
722 		unit->directory = ci.p + value - 1;
723 		unit->device.bus = &fw_bus_type;
724 		unit->device.type = &fw_unit_type;
725 		unit->device.parent = &device->device;
726 		dev_set_name(&unit->device, "%s.%d", dev_name(&device->device), i++);
727 
728 		BUILD_BUG_ON(ARRAY_SIZE(unit->attribute_group.attrs) <
729 				ARRAY_SIZE(fw_unit_attributes) +
730 				ARRAY_SIZE(config_rom_attributes));
731 		init_fw_attribute_group(&unit->device,
732 					fw_unit_attributes,
733 					&unit->attribute_group);
734 
735 		if (device_register(&unit->device) < 0)
736 			goto skip_unit;
737 
738 		fw_device_get(device);
739 		continue;
740 
741 	skip_unit:
742 		kfree(unit);
743 	}
744 }
745 
746 static int shutdown_unit(struct device *device, void *data)
747 {
748 	device_unregister(device);
749 
750 	return 0;
751 }
752 
753 /*
754  * fw_device_rwsem acts as dual purpose mutex:
755  *   - serializes accesses to fw_device_idr,
756  *   - serializes accesses to fw_device.config_rom/.config_rom_length and
757  *     fw_unit.directory, unless those accesses happen at safe occasions
758  */
759 DECLARE_RWSEM(fw_device_rwsem);
760 
761 DEFINE_IDR(fw_device_idr);
762 int fw_cdev_major;
763 
764 struct fw_device *fw_device_get_by_devt(dev_t devt)
765 {
766 	struct fw_device *device;
767 
768 	down_read(&fw_device_rwsem);
769 	device = idr_find(&fw_device_idr, MINOR(devt));
770 	if (device)
771 		fw_device_get(device);
772 	up_read(&fw_device_rwsem);
773 
774 	return device;
775 }
776 
777 struct workqueue_struct *fw_workqueue;
778 EXPORT_SYMBOL(fw_workqueue);
779 
780 static void fw_schedule_device_work(struct fw_device *device,
781 				    unsigned long delay)
782 {
783 	queue_delayed_work(fw_workqueue, &device->work, delay);
784 }
785 
786 /*
787  * These defines control the retry behavior for reading the config
788  * rom.  It shouldn't be necessary to tweak these; if the device
789  * doesn't respond to a config rom read within 10 seconds, it's not
790  * going to respond at all.  As for the initial delay, a lot of
791  * devices will be able to respond within half a second after bus
792  * reset.  On the other hand, it's not really worth being more
793  * aggressive than that, since it scales pretty well; if 10 devices
794  * are plugged in, they're all getting read within one second.
795  */
796 
797 #define MAX_RETRIES	10
798 #define RETRY_DELAY	(3 * HZ)
799 #define INITIAL_DELAY	(HZ / 2)
800 #define SHUTDOWN_DELAY	(2 * HZ)
801 
802 static void fw_device_shutdown(struct work_struct *work)
803 {
804 	struct fw_device *device =
805 		container_of(work, struct fw_device, work.work);
806 	int minor = MINOR(device->device.devt);
807 
808 	if (time_before64(get_jiffies_64(),
809 			  device->card->reset_jiffies + SHUTDOWN_DELAY)
810 	    && !list_empty(&device->card->link)) {
811 		fw_schedule_device_work(device, SHUTDOWN_DELAY);
812 		return;
813 	}
814 
815 	if (atomic_cmpxchg(&device->state,
816 			   FW_DEVICE_GONE,
817 			   FW_DEVICE_SHUTDOWN) != FW_DEVICE_GONE)
818 		return;
819 
820 	fw_device_cdev_remove(device);
821 	device_for_each_child(&device->device, NULL, shutdown_unit);
822 	device_unregister(&device->device);
823 
824 	down_write(&fw_device_rwsem);
825 	idr_remove(&fw_device_idr, minor);
826 	up_write(&fw_device_rwsem);
827 
828 	fw_device_put(device);
829 }
830 
831 static void fw_device_release(struct device *dev)
832 {
833 	struct fw_device *device = fw_device(dev);
834 	struct fw_card *card = device->card;
835 	unsigned long flags;
836 
837 	/*
838 	 * Take the card lock so we don't set this to NULL while a
839 	 * FW_NODE_UPDATED callback is being handled or while the
840 	 * bus manager work looks at this node.
841 	 */
842 	spin_lock_irqsave(&card->lock, flags);
843 	device->node->data = NULL;
844 	spin_unlock_irqrestore(&card->lock, flags);
845 
846 	fw_node_put(device->node);
847 	kfree(device->config_rom);
848 	kfree(device);
849 	fw_card_put(card);
850 }
851 
852 static struct device_type fw_device_type = {
853 	.release = fw_device_release,
854 };
855 
856 static bool is_fw_device(struct device *dev)
857 {
858 	return dev->type == &fw_device_type;
859 }
860 
861 static int update_unit(struct device *dev, void *data)
862 {
863 	struct fw_unit *unit = fw_unit(dev);
864 	struct fw_driver *driver = (struct fw_driver *)dev->driver;
865 
866 	if (is_fw_unit(dev) && driver != NULL && driver->update != NULL) {
867 		device_lock(dev);
868 		driver->update(unit);
869 		device_unlock(dev);
870 	}
871 
872 	return 0;
873 }
874 
875 static void fw_device_update(struct work_struct *work)
876 {
877 	struct fw_device *device =
878 		container_of(work, struct fw_device, work.work);
879 
880 	fw_device_cdev_update(device);
881 	device_for_each_child(&device->device, NULL, update_unit);
882 }
883 
884 /*
885  * If a device was pending for deletion because its node went away but its
886  * bus info block and root directory header matches that of a newly discovered
887  * device, revive the existing fw_device.
888  * The newly allocated fw_device becomes obsolete instead.
889  */
890 static int lookup_existing_device(struct device *dev, void *data)
891 {
892 	struct fw_device *old = fw_device(dev);
893 	struct fw_device *new = data;
894 	struct fw_card *card = new->card;
895 	int match = 0;
896 
897 	if (!is_fw_device(dev))
898 		return 0;
899 
900 	down_read(&fw_device_rwsem); /* serialize config_rom access */
901 	spin_lock_irq(&card->lock);  /* serialize node access */
902 
903 	if (memcmp(old->config_rom, new->config_rom, 6 * 4) == 0 &&
904 	    atomic_cmpxchg(&old->state,
905 			   FW_DEVICE_GONE,
906 			   FW_DEVICE_RUNNING) == FW_DEVICE_GONE) {
907 		struct fw_node *current_node = new->node;
908 		struct fw_node *obsolete_node = old->node;
909 
910 		new->node = obsolete_node;
911 		new->node->data = new;
912 		old->node = current_node;
913 		old->node->data = old;
914 
915 		old->max_speed = new->max_speed;
916 		old->node_id = current_node->node_id;
917 		smp_wmb();  /* update node_id before generation */
918 		old->generation = card->generation;
919 		old->config_rom_retries = 0;
920 		fw_notice(card, "rediscovered device %s\n", dev_name(dev));
921 
922 		old->workfn = fw_device_update;
923 		fw_schedule_device_work(old, 0);
924 
925 		if (current_node == card->root_node)
926 			fw_schedule_bm_work(card, 0);
927 
928 		match = 1;
929 	}
930 
931 	spin_unlock_irq(&card->lock);
932 	up_read(&fw_device_rwsem);
933 
934 	return match;
935 }
936 
937 enum { BC_UNKNOWN = 0, BC_UNIMPLEMENTED, BC_IMPLEMENTED, };
938 
939 static void set_broadcast_channel(struct fw_device *device, int generation)
940 {
941 	struct fw_card *card = device->card;
942 	__be32 data;
943 	int rcode;
944 
945 	if (!card->broadcast_channel_allocated)
946 		return;
947 
948 	/*
949 	 * The Broadcast_Channel Valid bit is required by nodes which want to
950 	 * transmit on this channel.  Such transmissions are practically
951 	 * exclusive to IP over 1394 (RFC 2734).  IP capable nodes are required
952 	 * to be IRM capable and have a max_rec of 8 or more.  We use this fact
953 	 * to narrow down to which nodes we send Broadcast_Channel updates.
954 	 */
955 	if (!device->irmc || device->max_rec < 8)
956 		return;
957 
958 	/*
959 	 * Some 1394-1995 nodes crash if this 1394a-2000 register is written.
960 	 * Perform a read test first.
961 	 */
962 	if (device->bc_implemented == BC_UNKNOWN) {
963 		rcode = fw_run_transaction(card, TCODE_READ_QUADLET_REQUEST,
964 				device->node_id, generation, device->max_speed,
965 				CSR_REGISTER_BASE + CSR_BROADCAST_CHANNEL,
966 				&data, 4);
967 		switch (rcode) {
968 		case RCODE_COMPLETE:
969 			if (data & cpu_to_be32(1 << 31)) {
970 				device->bc_implemented = BC_IMPLEMENTED;
971 				break;
972 			}
973 			/* else fall through to case address error */
974 		case RCODE_ADDRESS_ERROR:
975 			device->bc_implemented = BC_UNIMPLEMENTED;
976 		}
977 	}
978 
979 	if (device->bc_implemented == BC_IMPLEMENTED) {
980 		data = cpu_to_be32(BROADCAST_CHANNEL_INITIAL |
981 				   BROADCAST_CHANNEL_VALID);
982 		fw_run_transaction(card, TCODE_WRITE_QUADLET_REQUEST,
983 				device->node_id, generation, device->max_speed,
984 				CSR_REGISTER_BASE + CSR_BROADCAST_CHANNEL,
985 				&data, 4);
986 	}
987 }
988 
989 int fw_device_set_broadcast_channel(struct device *dev, void *gen)
990 {
991 	if (is_fw_device(dev))
992 		set_broadcast_channel(fw_device(dev), (long)gen);
993 
994 	return 0;
995 }
996 
997 static void fw_device_init(struct work_struct *work)
998 {
999 	struct fw_device *device =
1000 		container_of(work, struct fw_device, work.work);
1001 	struct fw_card *card = device->card;
1002 	struct device *revived_dev;
1003 	int minor, ret;
1004 
1005 	/*
1006 	 * All failure paths here set node->data to NULL, so that we
1007 	 * don't try to do device_for_each_child() on a kfree()'d
1008 	 * device.
1009 	 */
1010 
1011 	ret = read_config_rom(device, device->generation);
1012 	if (ret != RCODE_COMPLETE) {
1013 		if (device->config_rom_retries < MAX_RETRIES &&
1014 		    atomic_read(&device->state) == FW_DEVICE_INITIALIZING) {
1015 			device->config_rom_retries++;
1016 			fw_schedule_device_work(device, RETRY_DELAY);
1017 		} else {
1018 			if (device->node->link_on)
1019 				fw_notice(card, "giving up on node %x: reading config rom failed: %s\n",
1020 					  device->node_id,
1021 					  fw_rcode_string(ret));
1022 			if (device->node == card->root_node)
1023 				fw_schedule_bm_work(card, 0);
1024 			fw_device_release(&device->device);
1025 		}
1026 		return;
1027 	}
1028 
1029 	revived_dev = device_find_child(card->device,
1030 					device, lookup_existing_device);
1031 	if (revived_dev) {
1032 		put_device(revived_dev);
1033 		fw_device_release(&device->device);
1034 
1035 		return;
1036 	}
1037 
1038 	device_initialize(&device->device);
1039 
1040 	fw_device_get(device);
1041 	down_write(&fw_device_rwsem);
1042 	minor = idr_alloc(&fw_device_idr, device, 0, 1 << MINORBITS,
1043 			GFP_KERNEL);
1044 	up_write(&fw_device_rwsem);
1045 
1046 	if (minor < 0)
1047 		goto error;
1048 
1049 	device->device.bus = &fw_bus_type;
1050 	device->device.type = &fw_device_type;
1051 	device->device.parent = card->device;
1052 	device->device.devt = MKDEV(fw_cdev_major, minor);
1053 	dev_set_name(&device->device, "fw%d", minor);
1054 
1055 	BUILD_BUG_ON(ARRAY_SIZE(device->attribute_group.attrs) <
1056 			ARRAY_SIZE(fw_device_attributes) +
1057 			ARRAY_SIZE(config_rom_attributes));
1058 	init_fw_attribute_group(&device->device,
1059 				fw_device_attributes,
1060 				&device->attribute_group);
1061 
1062 	if (device_add(&device->device)) {
1063 		fw_err(card, "failed to add device\n");
1064 		goto error_with_cdev;
1065 	}
1066 
1067 	create_units(device);
1068 
1069 	/*
1070 	 * Transition the device to running state.  If it got pulled
1071 	 * out from under us while we did the initialization work, we
1072 	 * have to shut down the device again here.  Normally, though,
1073 	 * fw_node_event will be responsible for shutting it down when
1074 	 * necessary.  We have to use the atomic cmpxchg here to avoid
1075 	 * racing with the FW_NODE_DESTROYED case in
1076 	 * fw_node_event().
1077 	 */
1078 	if (atomic_cmpxchg(&device->state,
1079 			   FW_DEVICE_INITIALIZING,
1080 			   FW_DEVICE_RUNNING) == FW_DEVICE_GONE) {
1081 		device->workfn = fw_device_shutdown;
1082 		fw_schedule_device_work(device, SHUTDOWN_DELAY);
1083 	} else {
1084 		fw_notice(card, "created device %s: GUID %08x%08x, S%d00\n",
1085 			  dev_name(&device->device),
1086 			  device->config_rom[3], device->config_rom[4],
1087 			  1 << device->max_speed);
1088 		device->config_rom_retries = 0;
1089 
1090 		set_broadcast_channel(device, device->generation);
1091 
1092 		add_device_randomness(&device->config_rom[3], 8);
1093 	}
1094 
1095 	/*
1096 	 * Reschedule the IRM work if we just finished reading the
1097 	 * root node config rom.  If this races with a bus reset we
1098 	 * just end up running the IRM work a couple of extra times -
1099 	 * pretty harmless.
1100 	 */
1101 	if (device->node == card->root_node)
1102 		fw_schedule_bm_work(card, 0);
1103 
1104 	return;
1105 
1106  error_with_cdev:
1107 	down_write(&fw_device_rwsem);
1108 	idr_remove(&fw_device_idr, minor);
1109 	up_write(&fw_device_rwsem);
1110  error:
1111 	fw_device_put(device);		/* fw_device_idr's reference */
1112 
1113 	put_device(&device->device);	/* our reference */
1114 }
1115 
1116 /* Reread and compare bus info block and header of root directory */
1117 static int reread_config_rom(struct fw_device *device, int generation,
1118 			     bool *changed)
1119 {
1120 	u32 q;
1121 	int i, rcode;
1122 
1123 	for (i = 0; i < 6; i++) {
1124 		rcode = read_rom(device, generation, i, &q);
1125 		if (rcode != RCODE_COMPLETE)
1126 			return rcode;
1127 
1128 		if (i == 0 && q == 0)
1129 			/* inaccessible (see read_config_rom); retry later */
1130 			return RCODE_BUSY;
1131 
1132 		if (q != device->config_rom[i]) {
1133 			*changed = true;
1134 			return RCODE_COMPLETE;
1135 		}
1136 	}
1137 
1138 	*changed = false;
1139 	return RCODE_COMPLETE;
1140 }
1141 
1142 static void fw_device_refresh(struct work_struct *work)
1143 {
1144 	struct fw_device *device =
1145 		container_of(work, struct fw_device, work.work);
1146 	struct fw_card *card = device->card;
1147 	int ret, node_id = device->node_id;
1148 	bool changed;
1149 
1150 	ret = reread_config_rom(device, device->generation, &changed);
1151 	if (ret != RCODE_COMPLETE)
1152 		goto failed_config_rom;
1153 
1154 	if (!changed) {
1155 		if (atomic_cmpxchg(&device->state,
1156 				   FW_DEVICE_INITIALIZING,
1157 				   FW_DEVICE_RUNNING) == FW_DEVICE_GONE)
1158 			goto gone;
1159 
1160 		fw_device_update(work);
1161 		device->config_rom_retries = 0;
1162 		goto out;
1163 	}
1164 
1165 	/*
1166 	 * Something changed.  We keep things simple and don't investigate
1167 	 * further.  We just destroy all previous units and create new ones.
1168 	 */
1169 	device_for_each_child(&device->device, NULL, shutdown_unit);
1170 
1171 	ret = read_config_rom(device, device->generation);
1172 	if (ret != RCODE_COMPLETE)
1173 		goto failed_config_rom;
1174 
1175 	fw_device_cdev_update(device);
1176 	create_units(device);
1177 
1178 	/* Userspace may want to re-read attributes. */
1179 	kobject_uevent(&device->device.kobj, KOBJ_CHANGE);
1180 
1181 	if (atomic_cmpxchg(&device->state,
1182 			   FW_DEVICE_INITIALIZING,
1183 			   FW_DEVICE_RUNNING) == FW_DEVICE_GONE)
1184 		goto gone;
1185 
1186 	fw_notice(card, "refreshed device %s\n", dev_name(&device->device));
1187 	device->config_rom_retries = 0;
1188 	goto out;
1189 
1190  failed_config_rom:
1191 	if (device->config_rom_retries < MAX_RETRIES &&
1192 	    atomic_read(&device->state) == FW_DEVICE_INITIALIZING) {
1193 		device->config_rom_retries++;
1194 		fw_schedule_device_work(device, RETRY_DELAY);
1195 		return;
1196 	}
1197 
1198 	fw_notice(card, "giving up on refresh of device %s: %s\n",
1199 		  dev_name(&device->device), fw_rcode_string(ret));
1200  gone:
1201 	atomic_set(&device->state, FW_DEVICE_GONE);
1202 	device->workfn = fw_device_shutdown;
1203 	fw_schedule_device_work(device, SHUTDOWN_DELAY);
1204  out:
1205 	if (node_id == card->root_node->node_id)
1206 		fw_schedule_bm_work(card, 0);
1207 }
1208 
1209 static void fw_device_workfn(struct work_struct *work)
1210 {
1211 	struct fw_device *device = container_of(to_delayed_work(work),
1212 						struct fw_device, work);
1213 	device->workfn(work);
1214 }
1215 
1216 void fw_node_event(struct fw_card *card, struct fw_node *node, int event)
1217 {
1218 	struct fw_device *device;
1219 
1220 	switch (event) {
1221 	case FW_NODE_CREATED:
1222 		/*
1223 		 * Attempt to scan the node, regardless whether its self ID has
1224 		 * the L (link active) flag set or not.  Some broken devices
1225 		 * send L=0 but have an up-and-running link; others send L=1
1226 		 * without actually having a link.
1227 		 */
1228  create:
1229 		device = kzalloc(sizeof(*device), GFP_ATOMIC);
1230 		if (device == NULL)
1231 			break;
1232 
1233 		/*
1234 		 * Do minimal initialization of the device here, the
1235 		 * rest will happen in fw_device_init().
1236 		 *
1237 		 * Attention:  A lot of things, even fw_device_get(),
1238 		 * cannot be done before fw_device_init() finished!
1239 		 * You can basically just check device->state and
1240 		 * schedule work until then, but only while holding
1241 		 * card->lock.
1242 		 */
1243 		atomic_set(&device->state, FW_DEVICE_INITIALIZING);
1244 		device->card = fw_card_get(card);
1245 		device->node = fw_node_get(node);
1246 		device->node_id = node->node_id;
1247 		device->generation = card->generation;
1248 		device->is_local = node == card->local_node;
1249 		mutex_init(&device->client_list_mutex);
1250 		INIT_LIST_HEAD(&device->client_list);
1251 
1252 		/*
1253 		 * Set the node data to point back to this device so
1254 		 * FW_NODE_UPDATED callbacks can update the node_id
1255 		 * and generation for the device.
1256 		 */
1257 		node->data = device;
1258 
1259 		/*
1260 		 * Many devices are slow to respond after bus resets,
1261 		 * especially if they are bus powered and go through
1262 		 * power-up after getting plugged in.  We schedule the
1263 		 * first config rom scan half a second after bus reset.
1264 		 */
1265 		device->workfn = fw_device_init;
1266 		INIT_DELAYED_WORK(&device->work, fw_device_workfn);
1267 		fw_schedule_device_work(device, INITIAL_DELAY);
1268 		break;
1269 
1270 	case FW_NODE_INITIATED_RESET:
1271 	case FW_NODE_LINK_ON:
1272 		device = node->data;
1273 		if (device == NULL)
1274 			goto create;
1275 
1276 		device->node_id = node->node_id;
1277 		smp_wmb();  /* update node_id before generation */
1278 		device->generation = card->generation;
1279 		if (atomic_cmpxchg(&device->state,
1280 			    FW_DEVICE_RUNNING,
1281 			    FW_DEVICE_INITIALIZING) == FW_DEVICE_RUNNING) {
1282 			device->workfn = fw_device_refresh;
1283 			fw_schedule_device_work(device,
1284 				device->is_local ? 0 : INITIAL_DELAY);
1285 		}
1286 		break;
1287 
1288 	case FW_NODE_UPDATED:
1289 		device = node->data;
1290 		if (device == NULL)
1291 			break;
1292 
1293 		device->node_id = node->node_id;
1294 		smp_wmb();  /* update node_id before generation */
1295 		device->generation = card->generation;
1296 		if (atomic_read(&device->state) == FW_DEVICE_RUNNING) {
1297 			device->workfn = fw_device_update;
1298 			fw_schedule_device_work(device, 0);
1299 		}
1300 		break;
1301 
1302 	case FW_NODE_DESTROYED:
1303 	case FW_NODE_LINK_OFF:
1304 		if (!node->data)
1305 			break;
1306 
1307 		/*
1308 		 * Destroy the device associated with the node.  There
1309 		 * are two cases here: either the device is fully
1310 		 * initialized (FW_DEVICE_RUNNING) or we're in the
1311 		 * process of reading its config rom
1312 		 * (FW_DEVICE_INITIALIZING).  If it is fully
1313 		 * initialized we can reuse device->work to schedule a
1314 		 * full fw_device_shutdown().  If not, there's work
1315 		 * scheduled to read it's config rom, and we just put
1316 		 * the device in shutdown state to have that code fail
1317 		 * to create the device.
1318 		 */
1319 		device = node->data;
1320 		if (atomic_xchg(&device->state,
1321 				FW_DEVICE_GONE) == FW_DEVICE_RUNNING) {
1322 			device->workfn = fw_device_shutdown;
1323 			fw_schedule_device_work(device,
1324 				list_empty(&card->link) ? 0 : SHUTDOWN_DELAY);
1325 		}
1326 		break;
1327 	}
1328 }
1329