1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 * Copyright (C) 2005-2007 Kristian Hoegsberg <krh@bitplanet.net>
4 */
5
6#include <linux/bug.h>
7#include <linux/completion.h>
8#include <linux/crc-itu-t.h>
9#include <linux/device.h>
10#include <linux/errno.h>
11#include <linux/firewire.h>
12#include <linux/firewire-constants.h>
13#include <linux/jiffies.h>
14#include <linux/kernel.h>
15#include <linux/kref.h>
16#include <linux/list.h>
17#include <linux/module.h>
18#include <linux/mutex.h>
19#include <linux/spinlock.h>
20#include <linux/workqueue.h>
21
22#include <linux/atomic.h>
23#include <asm/byteorder.h>
24
25#include "core.h"
26
27#define define_fw_printk_level(func, kern_level) \
28void func(const struct fw_card *card, const char *fmt, ...) \
29{ \
30 struct va_format vaf; \
31 va_list args; \
32 \
33 va_start(args, fmt); \
34 vaf.fmt = fmt; \
35 vaf.va = &args; \
36 printk(kern_level KBUILD_MODNAME " %s: %pV", \
37 dev_name(card->device), &vaf); \
38 va_end(args); \
39}
40define_fw_printk_level(fw_err, KERN_ERR);
41define_fw_printk_level(fw_notice, KERN_NOTICE);
42
43int fw_compute_block_crc(__be32 *block)
44{
45 int length;
46 u16 crc;
47
48 length = (be32_to_cpu(block[0]) >> 16) & 0xff;
49 crc = crc_itu_t(crc: 0, buffer: (u8 *)&block[1], len: length * 4);
50 *block |= cpu_to_be32(crc);
51
52 return length;
53}
54
55static DEFINE_MUTEX(card_mutex);
56static LIST_HEAD(card_list);
57
58static LIST_HEAD(descriptor_list);
59static int descriptor_count;
60
61static __be32 tmp_config_rom[256];
62/* ROM header, bus info block, root dir header, capabilities = 7 quadlets */
63static size_t config_rom_length = 1 + 4 + 1 + 1;
64
65#define BIB_CRC(v) ((v) << 0)
66#define BIB_CRC_LENGTH(v) ((v) << 16)
67#define BIB_INFO_LENGTH(v) ((v) << 24)
68#define BIB_BUS_NAME 0x31333934 /* "1394" */
69#define BIB_LINK_SPEED(v) ((v) << 0)
70#define BIB_GENERATION(v) ((v) << 4)
71#define BIB_MAX_ROM(v) ((v) << 8)
72#define BIB_MAX_RECEIVE(v) ((v) << 12)
73#define BIB_CYC_CLK_ACC(v) ((v) << 16)
74#define BIB_PMC ((1) << 27)
75#define BIB_BMC ((1) << 28)
76#define BIB_ISC ((1) << 29)
77#define BIB_CMC ((1) << 30)
78#define BIB_IRMC ((1) << 31)
79#define NODE_CAPABILITIES 0x0c0083c0 /* per IEEE 1394 clause 8.3.2.6.5.2 */
80
81/*
82 * IEEE-1394 specifies a default SPLIT_TIMEOUT value of 800 cycles (100 ms),
83 * but we have to make it longer because there are many devices whose firmware
84 * is just too slow for that.
85 */
86#define DEFAULT_SPLIT_TIMEOUT (2 * 8000)
87
88#define CANON_OUI 0x000085
89
90static void generate_config_rom(struct fw_card *card, __be32 *config_rom)
91{
92 struct fw_descriptor *desc;
93 int i, j, k, length;
94
95 /*
96 * Initialize contents of config rom buffer. On the OHCI
97 * controller, block reads to the config rom accesses the host
98 * memory, but quadlet read access the hardware bus info block
99 * registers. That's just crack, but it means we should make
100 * sure the contents of bus info block in host memory matches
101 * the version stored in the OHCI registers.
102 */
103
104 config_rom[0] = cpu_to_be32(
105 BIB_CRC_LENGTH(4) | BIB_INFO_LENGTH(4) | BIB_CRC(0));
106 config_rom[1] = cpu_to_be32(BIB_BUS_NAME);
107 config_rom[2] = cpu_to_be32(
108 BIB_LINK_SPEED(card->link_speed) |
109 BIB_GENERATION(card->config_rom_generation++ % 14 + 2) |
110 BIB_MAX_ROM(2) |
111 BIB_MAX_RECEIVE(card->max_receive) |
112 BIB_BMC | BIB_ISC | BIB_CMC | BIB_IRMC);
113 config_rom[3] = cpu_to_be32(card->guid >> 32);
114 config_rom[4] = cpu_to_be32(card->guid);
115
116 /* Generate root directory. */
117 config_rom[6] = cpu_to_be32(NODE_CAPABILITIES);
118 i = 7;
119 j = 7 + descriptor_count;
120
121 /* Generate root directory entries for descriptors. */
122 list_for_each_entry (desc, &descriptor_list, link) {
123 if (desc->immediate > 0)
124 config_rom[i++] = cpu_to_be32(desc->immediate);
125 config_rom[i] = cpu_to_be32(desc->key | (j - i));
126 i++;
127 j += desc->length;
128 }
129
130 /* Update root directory length. */
131 config_rom[5] = cpu_to_be32((i - 5 - 1) << 16);
132
133 /* End of root directory, now copy in descriptors. */
134 list_for_each_entry (desc, &descriptor_list, link) {
135 for (k = 0; k < desc->length; k++)
136 config_rom[i + k] = cpu_to_be32(desc->data[k]);
137 i += desc->length;
138 }
139
140 /* Calculate CRCs for all blocks in the config rom. This
141 * assumes that CRC length and info length are identical for
142 * the bus info block, which is always the case for this
143 * implementation. */
144 for (i = 0; i < j; i += length + 1)
145 length = fw_compute_block_crc(block: config_rom + i);
146
147 WARN_ON(j != config_rom_length);
148}
149
150static void update_config_roms(void)
151{
152 struct fw_card *card;
153
154 list_for_each_entry (card, &card_list, link) {
155 generate_config_rom(card, config_rom: tmp_config_rom);
156 card->driver->set_config_rom(card, tmp_config_rom,
157 config_rom_length);
158 }
159}
160
161static size_t required_space(struct fw_descriptor *desc)
162{
163 /* descriptor + entry into root dir + optional immediate entry */
164 return desc->length + 1 + (desc->immediate > 0 ? 1 : 0);
165}
166
167int fw_core_add_descriptor(struct fw_descriptor *desc)
168{
169 size_t i;
170 int ret;
171
172 /*
173 * Check descriptor is valid; the length of all blocks in the
174 * descriptor has to add up to exactly the length of the
175 * block.
176 */
177 i = 0;
178 while (i < desc->length)
179 i += (desc->data[i] >> 16) + 1;
180
181 if (i != desc->length)
182 return -EINVAL;
183
184 mutex_lock(&card_mutex);
185
186 if (config_rom_length + required_space(desc) > 256) {
187 ret = -EBUSY;
188 } else {
189 list_add_tail(new: &desc->link, head: &descriptor_list);
190 config_rom_length += required_space(desc);
191 descriptor_count++;
192 if (desc->immediate > 0)
193 descriptor_count++;
194 update_config_roms();
195 ret = 0;
196 }
197
198 mutex_unlock(lock: &card_mutex);
199
200 return ret;
201}
202EXPORT_SYMBOL(fw_core_add_descriptor);
203
204void fw_core_remove_descriptor(struct fw_descriptor *desc)
205{
206 mutex_lock(&card_mutex);
207
208 list_del(entry: &desc->link);
209 config_rom_length -= required_space(desc);
210 descriptor_count--;
211 if (desc->immediate > 0)
212 descriptor_count--;
213 update_config_roms();
214
215 mutex_unlock(lock: &card_mutex);
216}
217EXPORT_SYMBOL(fw_core_remove_descriptor);
218
219static int reset_bus(struct fw_card *card, bool short_reset)
220{
221 int reg = short_reset ? 5 : 1;
222 int bit = short_reset ? PHY_BUS_SHORT_RESET : PHY_BUS_RESET;
223
224 return card->driver->update_phy_reg(card, reg, 0, bit);
225}
226
227void fw_schedule_bus_reset(struct fw_card *card, bool delayed, bool short_reset)
228{
229 /* We don't try hard to sort out requests of long vs. short resets. */
230 card->br_short = short_reset;
231
232 /* Use an arbitrary short delay to combine multiple reset requests. */
233 fw_card_get(card);
234 if (!queue_delayed_work(wq: fw_workqueue, dwork: &card->br_work,
235 delay: delayed ? DIV_ROUND_UP(HZ, 100) : 0))
236 fw_card_put(card);
237}
238EXPORT_SYMBOL(fw_schedule_bus_reset);
239
240static void br_work(struct work_struct *work)
241{
242 struct fw_card *card = container_of(work, struct fw_card, br_work.work);
243
244 /* Delay for 2s after last reset per IEEE 1394 clause 8.2.1. */
245 if (card->reset_jiffies != 0 &&
246 time_before64(get_jiffies_64(), card->reset_jiffies + 2 * HZ)) {
247 if (!queue_delayed_work(wq: fw_workqueue, dwork: &card->br_work, delay: 2 * HZ))
248 fw_card_put(card);
249 return;
250 }
251
252 fw_send_phy_config(card, FW_PHY_CONFIG_NO_NODE_ID, generation: card->generation,
253 FW_PHY_CONFIG_CURRENT_GAP_COUNT);
254 reset_bus(card, short_reset: card->br_short);
255 fw_card_put(card);
256}
257
258static void allocate_broadcast_channel(struct fw_card *card, int generation)
259{
260 int channel, bandwidth = 0;
261
262 if (!card->broadcast_channel_allocated) {
263 fw_iso_resource_manage(card, generation, channels_mask: 1ULL << 31,
264 channel: &channel, bandwidth: &bandwidth, allocate: true);
265 if (channel != 31) {
266 fw_notice(card, fmt: "failed to allocate broadcast channel\n");
267 return;
268 }
269 card->broadcast_channel_allocated = true;
270 }
271
272 device_for_each_child(dev: card->device, data: (void *)(long)generation,
273 fn: fw_device_set_broadcast_channel);
274}
275
276static const char gap_count_table[] = {
277 63, 5, 7, 8, 10, 13, 16, 18, 21, 24, 26, 29, 32, 35, 37, 40
278};
279
280void fw_schedule_bm_work(struct fw_card *card, unsigned long delay)
281{
282 fw_card_get(card);
283 if (!schedule_delayed_work(dwork: &card->bm_work, delay))
284 fw_card_put(card);
285}
286
287static void bm_work(struct work_struct *work)
288{
289 struct fw_card *card = container_of(work, struct fw_card, bm_work.work);
290 struct fw_device *root_device, *irm_device;
291 struct fw_node *root_node;
292 int root_id, new_root_id, irm_id, bm_id, local_id;
293 int gap_count, generation, grace, rcode;
294 bool do_reset = false;
295 bool root_device_is_running;
296 bool root_device_is_cmc;
297 bool irm_is_1394_1995_only;
298 bool keep_this_irm;
299 __be32 transaction_data[2];
300
301 spin_lock_irq(lock: &card->lock);
302
303 if (card->local_node == NULL) {
304 spin_unlock_irq(lock: &card->lock);
305 goto out_put_card;
306 }
307
308 generation = card->generation;
309
310 root_node = card->root_node;
311 fw_node_get(node: root_node);
312 root_device = root_node->data;
313 root_device_is_running = root_device &&
314 atomic_read(v: &root_device->state) == FW_DEVICE_RUNNING;
315 root_device_is_cmc = root_device && root_device->cmc;
316
317 irm_device = card->irm_node->data;
318 irm_is_1394_1995_only = irm_device && irm_device->config_rom &&
319 (irm_device->config_rom[2] & 0x000000f0) == 0;
320
321 /* Canon MV5i works unreliably if it is not root node. */
322 keep_this_irm = irm_device && irm_device->config_rom &&
323 irm_device->config_rom[3] >> 8 == CANON_OUI;
324
325 root_id = root_node->node_id;
326 irm_id = card->irm_node->node_id;
327 local_id = card->local_node->node_id;
328
329 grace = time_after64(get_jiffies_64(),
330 card->reset_jiffies + DIV_ROUND_UP(HZ, 8));
331
332 if ((is_next_generation(new_generation: generation, old_generation: card->bm_generation) &&
333 !card->bm_abdicate) ||
334 (card->bm_generation != generation && grace)) {
335 /*
336 * This first step is to figure out who is IRM and
337 * then try to become bus manager. If the IRM is not
338 * well defined (e.g. does not have an active link
339 * layer or does not responds to our lock request, we
340 * will have to do a little vigilante bus management.
341 * In that case, we do a goto into the gap count logic
342 * so that when we do the reset, we still optimize the
343 * gap count. That could well save a reset in the
344 * next generation.
345 */
346
347 if (!card->irm_node->link_on) {
348 new_root_id = local_id;
349 fw_notice(card, fmt: "%s, making local node (%02x) root\n",
350 "IRM has link off", new_root_id);
351 goto pick_me;
352 }
353
354 if (irm_is_1394_1995_only && !keep_this_irm) {
355 new_root_id = local_id;
356 fw_notice(card, fmt: "%s, making local node (%02x) root\n",
357 "IRM is not 1394a compliant", new_root_id);
358 goto pick_me;
359 }
360
361 transaction_data[0] = cpu_to_be32(0x3f);
362 transaction_data[1] = cpu_to_be32(local_id);
363
364 spin_unlock_irq(lock: &card->lock);
365
366 rcode = fw_run_transaction(card, TCODE_LOCK_COMPARE_SWAP,
367 destination_id: irm_id, generation, SCODE_100,
368 CSR_REGISTER_BASE + CSR_BUS_MANAGER_ID,
369 payload: transaction_data, length: 8);
370
371 if (rcode == RCODE_GENERATION)
372 /* Another bus reset, BM work has been rescheduled. */
373 goto out;
374
375 bm_id = be32_to_cpu(transaction_data[0]);
376
377 spin_lock_irq(lock: &card->lock);
378 if (rcode == RCODE_COMPLETE && generation == card->generation)
379 card->bm_node_id =
380 bm_id == 0x3f ? local_id : 0xffc0 | bm_id;
381 spin_unlock_irq(lock: &card->lock);
382
383 if (rcode == RCODE_COMPLETE && bm_id != 0x3f) {
384 /* Somebody else is BM. Only act as IRM. */
385 if (local_id == irm_id)
386 allocate_broadcast_channel(card, generation);
387
388 goto out;
389 }
390
391 if (rcode == RCODE_SEND_ERROR) {
392 /*
393 * We have been unable to send the lock request due to
394 * some local problem. Let's try again later and hope
395 * that the problem has gone away by then.
396 */
397 fw_schedule_bm_work(card, DIV_ROUND_UP(HZ, 8));
398 goto out;
399 }
400
401 spin_lock_irq(lock: &card->lock);
402
403 if (rcode != RCODE_COMPLETE && !keep_this_irm) {
404 /*
405 * The lock request failed, maybe the IRM
406 * isn't really IRM capable after all. Let's
407 * do a bus reset and pick the local node as
408 * root, and thus, IRM.
409 */
410 new_root_id = local_id;
411 fw_notice(card, fmt: "BM lock failed (%s), making local node (%02x) root\n",
412 fw_rcode_string(rcode), new_root_id);
413 goto pick_me;
414 }
415 } else if (card->bm_generation != generation) {
416 /*
417 * We weren't BM in the last generation, and the last
418 * bus reset is less than 125ms ago. Reschedule this job.
419 */
420 spin_unlock_irq(lock: &card->lock);
421 fw_schedule_bm_work(card, DIV_ROUND_UP(HZ, 8));
422 goto out;
423 }
424
425 /*
426 * We're bus manager for this generation, so next step is to
427 * make sure we have an active cycle master and do gap count
428 * optimization.
429 */
430 card->bm_generation = generation;
431
432 if (root_device == NULL) {
433 /*
434 * Either link_on is false, or we failed to read the
435 * config rom. In either case, pick another root.
436 */
437 new_root_id = local_id;
438 } else if (!root_device_is_running) {
439 /*
440 * If we haven't probed this device yet, bail out now
441 * and let's try again once that's done.
442 */
443 spin_unlock_irq(lock: &card->lock);
444 goto out;
445 } else if (root_device_is_cmc) {
446 /*
447 * We will send out a force root packet for this
448 * node as part of the gap count optimization.
449 */
450 new_root_id = root_id;
451 } else {
452 /*
453 * Current root has an active link layer and we
454 * successfully read the config rom, but it's not
455 * cycle master capable.
456 */
457 new_root_id = local_id;
458 }
459
460 pick_me:
461 /*
462 * Pick a gap count from 1394a table E-1. The table doesn't cover
463 * the typically much larger 1394b beta repeater delays though.
464 */
465 if (!card->beta_repeaters_present &&
466 root_node->max_hops < ARRAY_SIZE(gap_count_table))
467 gap_count = gap_count_table[root_node->max_hops];
468 else
469 gap_count = 63;
470
471 /*
472 * Finally, figure out if we should do a reset or not. If we have
473 * done less than 5 resets with the same physical topology and we
474 * have either a new root or a new gap count setting, let's do it.
475 */
476
477 if (card->bm_retries++ < 5 &&
478 (card->gap_count != gap_count || new_root_id != root_id))
479 do_reset = true;
480
481 spin_unlock_irq(lock: &card->lock);
482
483 if (do_reset) {
484 fw_notice(card, fmt: "phy config: new root=%x, gap_count=%d\n",
485 new_root_id, gap_count);
486 fw_send_phy_config(card, node_id: new_root_id, generation, gap_count);
487 reset_bus(card, short_reset: true);
488 /* Will allocate broadcast channel after the reset. */
489 goto out;
490 }
491
492 if (root_device_is_cmc) {
493 /*
494 * Make sure that the cycle master sends cycle start packets.
495 */
496 transaction_data[0] = cpu_to_be32(CSR_STATE_BIT_CMSTR);
497 rcode = fw_run_transaction(card, TCODE_WRITE_QUADLET_REQUEST,
498 destination_id: root_id, generation, SCODE_100,
499 CSR_REGISTER_BASE + CSR_STATE_SET,
500 payload: transaction_data, length: 4);
501 if (rcode == RCODE_GENERATION)
502 goto out;
503 }
504
505 if (local_id == irm_id)
506 allocate_broadcast_channel(card, generation);
507
508 out:
509 fw_node_put(node: root_node);
510 out_put_card:
511 fw_card_put(card);
512}
513
514void fw_card_initialize(struct fw_card *card,
515 const struct fw_card_driver *driver,
516 struct device *device)
517{
518 static atomic_t index = ATOMIC_INIT(-1);
519
520 card->index = atomic_inc_return(v: &index);
521 card->driver = driver;
522 card->device = device;
523 card->current_tlabel = 0;
524 card->tlabel_mask = 0;
525 card->split_timeout_hi = DEFAULT_SPLIT_TIMEOUT / 8000;
526 card->split_timeout_lo = (DEFAULT_SPLIT_TIMEOUT % 8000) << 19;
527 card->split_timeout_cycles = DEFAULT_SPLIT_TIMEOUT;
528 card->split_timeout_jiffies =
529 DIV_ROUND_UP(DEFAULT_SPLIT_TIMEOUT * HZ, 8000);
530 card->color = 0;
531 card->broadcast_channel = BROADCAST_CHANNEL_INITIAL;
532
533 kref_init(kref: &card->kref);
534 init_completion(x: &card->done);
535 INIT_LIST_HEAD(list: &card->transaction_list);
536 INIT_LIST_HEAD(list: &card->phy_receiver_list);
537 spin_lock_init(&card->lock);
538
539 card->local_node = NULL;
540
541 INIT_DELAYED_WORK(&card->br_work, br_work);
542 INIT_DELAYED_WORK(&card->bm_work, bm_work);
543}
544EXPORT_SYMBOL(fw_card_initialize);
545
546int fw_card_add(struct fw_card *card,
547 u32 max_receive, u32 link_speed, u64 guid)
548{
549 int ret;
550
551 card->max_receive = max_receive;
552 card->link_speed = link_speed;
553 card->guid = guid;
554
555 mutex_lock(&card_mutex);
556
557 generate_config_rom(card, config_rom: tmp_config_rom);
558 ret = card->driver->enable(card, tmp_config_rom, config_rom_length);
559 if (ret == 0)
560 list_add_tail(new: &card->link, head: &card_list);
561
562 mutex_unlock(lock: &card_mutex);
563
564 return ret;
565}
566EXPORT_SYMBOL(fw_card_add);
567
568/*
569 * The next few functions implement a dummy driver that is used once a card
570 * driver shuts down an fw_card. This allows the driver to cleanly unload,
571 * as all IO to the card will be handled (and failed) by the dummy driver
572 * instead of calling into the module. Only functions for iso context
573 * shutdown still need to be provided by the card driver.
574 *
575 * .read/write_csr() should never be called anymore after the dummy driver
576 * was bound since they are only used within request handler context.
577 * .set_config_rom() is never called since the card is taken out of card_list
578 * before switching to the dummy driver.
579 */
580
581static int dummy_read_phy_reg(struct fw_card *card, int address)
582{
583 return -ENODEV;
584}
585
586static int dummy_update_phy_reg(struct fw_card *card, int address,
587 int clear_bits, int set_bits)
588{
589 return -ENODEV;
590}
591
592static void dummy_send_request(struct fw_card *card, struct fw_packet *packet)
593{
594 packet->callback(packet, card, RCODE_CANCELLED);
595}
596
597static void dummy_send_response(struct fw_card *card, struct fw_packet *packet)
598{
599 packet->callback(packet, card, RCODE_CANCELLED);
600}
601
602static int dummy_cancel_packet(struct fw_card *card, struct fw_packet *packet)
603{
604 return -ENOENT;
605}
606
607static int dummy_enable_phys_dma(struct fw_card *card,
608 int node_id, int generation)
609{
610 return -ENODEV;
611}
612
613static struct fw_iso_context *dummy_allocate_iso_context(struct fw_card *card,
614 int type, int channel, size_t header_size)
615{
616 return ERR_PTR(error: -ENODEV);
617}
618
619static u32 dummy_read_csr(struct fw_card *card, int csr_offset)
620{
621 return 0;
622}
623
624static void dummy_write_csr(struct fw_card *card, int csr_offset, u32 value)
625{
626}
627
628static int dummy_start_iso(struct fw_iso_context *ctx,
629 s32 cycle, u32 sync, u32 tags)
630{
631 return -ENODEV;
632}
633
634static int dummy_set_iso_channels(struct fw_iso_context *ctx, u64 *channels)
635{
636 return -ENODEV;
637}
638
639static int dummy_queue_iso(struct fw_iso_context *ctx, struct fw_iso_packet *p,
640 struct fw_iso_buffer *buffer, unsigned long payload)
641{
642 return -ENODEV;
643}
644
645static void dummy_flush_queue_iso(struct fw_iso_context *ctx)
646{
647}
648
649static int dummy_flush_iso_completions(struct fw_iso_context *ctx)
650{
651 return -ENODEV;
652}
653
654static const struct fw_card_driver dummy_driver_template = {
655 .read_phy_reg = dummy_read_phy_reg,
656 .update_phy_reg = dummy_update_phy_reg,
657 .send_request = dummy_send_request,
658 .send_response = dummy_send_response,
659 .cancel_packet = dummy_cancel_packet,
660 .enable_phys_dma = dummy_enable_phys_dma,
661 .read_csr = dummy_read_csr,
662 .write_csr = dummy_write_csr,
663 .allocate_iso_context = dummy_allocate_iso_context,
664 .start_iso = dummy_start_iso,
665 .set_iso_channels = dummy_set_iso_channels,
666 .queue_iso = dummy_queue_iso,
667 .flush_queue_iso = dummy_flush_queue_iso,
668 .flush_iso_completions = dummy_flush_iso_completions,
669};
670
671void fw_card_release(struct kref *kref)
672{
673 struct fw_card *card = container_of(kref, struct fw_card, kref);
674
675 complete(&card->done);
676}
677EXPORT_SYMBOL_GPL(fw_card_release);
678
679void fw_core_remove_card(struct fw_card *card)
680{
681 struct fw_card_driver dummy_driver = dummy_driver_template;
682 unsigned long flags;
683
684 card->driver->update_phy_reg(card, 4,
685 PHY_LINK_ACTIVE | PHY_CONTENDER, 0);
686 fw_schedule_bus_reset(card, false, true);
687
688 mutex_lock(&card_mutex);
689 list_del_init(entry: &card->link);
690 mutex_unlock(lock: &card_mutex);
691
692 /* Switch off most of the card driver interface. */
693 dummy_driver.free_iso_context = card->driver->free_iso_context;
694 dummy_driver.stop_iso = card->driver->stop_iso;
695 card->driver = &dummy_driver;
696
697 spin_lock_irqsave(&card->lock, flags);
698 fw_destroy_nodes(card);
699 spin_unlock_irqrestore(lock: &card->lock, flags);
700
701 /* Wait for all users, especially device workqueue jobs, to finish. */
702 fw_card_put(card);
703 wait_for_completion(&card->done);
704
705 WARN_ON(!list_empty(&card->transaction_list));
706}
707EXPORT_SYMBOL(fw_core_remove_card);
708
709/**
710 * fw_card_read_cycle_time: read from Isochronous Cycle Timer Register of 1394 OHCI in MMIO region
711 * for controller card.
712 * @card: The instance of card for 1394 OHCI controller.
713 * @cycle_time: The mutual reference to value of cycle time for the read operation.
714 *
715 * Read value from Isochronous Cycle Timer Register of 1394 OHCI in MMIO region for the given
716 * controller card. This function accesses the region without any lock primitives or IRQ mask.
717 * When returning successfully, the content of @value argument has value aligned to host endianness,
718 * formetted by CYCLE_TIME CSR Register of IEEE 1394 std.
719 *
720 * Context: Any context.
721 * Return:
722 * * 0 - Read successfully.
723 * * -ENODEV - The controller is unavailable due to being removed or unbound.
724 */
725int fw_card_read_cycle_time(struct fw_card *card, u32 *cycle_time)
726{
727 if (card->driver->read_csr == dummy_read_csr)
728 return -ENODEV;
729
730 // It's possible to switch to dummy driver between the above and the below. This is the best
731 // effort to return -ENODEV.
732 *cycle_time = card->driver->read_csr(card, CSR_CYCLE_TIME);
733 return 0;
734}
735EXPORT_SYMBOL_GPL(fw_card_read_cycle_time);
736

source code of linux/drivers/firewire/core-card.c