1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Apple iSight audio driver
4 *
5 * Copyright (c) Clemens Ladisch <clemens@ladisch.de>
6 */
7
8#include <asm/byteorder.h>
9#include <linux/delay.h>
10#include <linux/device.h>
11#include <linux/firewire.h>
12#include <linux/firewire-constants.h>
13#include <linux/module.h>
14#include <linux/mod_devicetable.h>
15#include <linux/mutex.h>
16#include <linux/string.h>
17#include <sound/control.h>
18#include <sound/core.h>
19#include <sound/initval.h>
20#include <sound/pcm.h>
21#include <sound/tlv.h>
22#include "lib.h"
23#include "iso-resources.h"
24#include "packets-buffer.h"
25
26#define OUI_APPLE 0x000a27
27#define MODEL_APPLE_ISIGHT 0x000008
28#define SW_ISIGHT_AUDIO 0x000010
29
30#define REG_AUDIO_ENABLE 0x000
31#define AUDIO_ENABLE 0x80000000
32#define REG_DEF_AUDIO_GAIN 0x204
33#define REG_GAIN_RAW_START 0x210
34#define REG_GAIN_RAW_END 0x214
35#define REG_GAIN_DB_START 0x218
36#define REG_GAIN_DB_END 0x21c
37#define REG_SAMPLE_RATE_INQUIRY 0x280
38#define REG_ISO_TX_CONFIG 0x300
39#define SPEED_SHIFT 16
40#define REG_SAMPLE_RATE 0x400
41#define RATE_48000 0x80000000
42#define REG_GAIN 0x500
43#define REG_MUTE 0x504
44
45#define MAX_FRAMES_PER_PACKET 475
46
47#define QUEUE_LENGTH 20
48
49struct isight {
50 struct snd_card *card;
51 struct fw_unit *unit;
52 struct fw_device *device;
53 u64 audio_base;
54 struct snd_pcm_substream *pcm;
55 struct mutex mutex;
56 struct iso_packets_buffer buffer;
57 struct fw_iso_resources resources;
58 struct fw_iso_context *context;
59 bool pcm_active;
60 bool pcm_running;
61 bool first_packet;
62 int packet_index;
63 u32 total_samples;
64 unsigned int buffer_pointer;
65 unsigned int period_counter;
66 s32 gain_min, gain_max;
67 unsigned int gain_tlv[4];
68};
69
70struct audio_payload {
71 __be32 sample_count;
72 __be32 signature;
73 __be32 sample_total;
74 __be32 reserved;
75 __be16 samples[2 * MAX_FRAMES_PER_PACKET];
76};
77
78MODULE_DESCRIPTION("iSight audio driver");
79MODULE_AUTHOR("Clemens Ladisch <clemens@ladisch.de>");
80MODULE_LICENSE("GPL");
81
82static struct fw_iso_packet audio_packet = {
83 .payload_length = sizeof(struct audio_payload),
84 .interrupt = 1,
85 .header_length = 4,
86};
87
88static void isight_update_pointers(struct isight *isight, unsigned int count)
89{
90 struct snd_pcm_runtime *runtime = isight->pcm->runtime;
91 unsigned int ptr;
92
93 smp_wmb(); /* update buffer data before buffer pointer */
94
95 ptr = isight->buffer_pointer;
96 ptr += count;
97 if (ptr >= runtime->buffer_size)
98 ptr -= runtime->buffer_size;
99 WRITE_ONCE(isight->buffer_pointer, ptr);
100
101 isight->period_counter += count;
102 if (isight->period_counter >= runtime->period_size) {
103 isight->period_counter -= runtime->period_size;
104 snd_pcm_period_elapsed(substream: isight->pcm);
105 }
106}
107
108static void isight_samples(struct isight *isight,
109 const __be16 *samples, unsigned int count)
110{
111 struct snd_pcm_runtime *runtime;
112 unsigned int count1;
113
114 if (!READ_ONCE(isight->pcm_running))
115 return;
116
117 runtime = isight->pcm->runtime;
118 if (isight->buffer_pointer + count <= runtime->buffer_size) {
119 memcpy(runtime->dma_area + isight->buffer_pointer * 4,
120 samples, count * 4);
121 } else {
122 count1 = runtime->buffer_size - isight->buffer_pointer;
123 memcpy(runtime->dma_area + isight->buffer_pointer * 4,
124 samples, count1 * 4);
125 samples += count1 * 2;
126 memcpy(runtime->dma_area, samples, (count - count1) * 4);
127 }
128
129 isight_update_pointers(isight, count);
130}
131
132static void isight_pcm_abort(struct isight *isight)
133{
134 if (READ_ONCE(isight->pcm_active))
135 snd_pcm_stop_xrun(substream: isight->pcm);
136}
137
138static void isight_dropped_samples(struct isight *isight, unsigned int total)
139{
140 struct snd_pcm_runtime *runtime;
141 u32 dropped;
142 unsigned int count1;
143
144 if (!READ_ONCE(isight->pcm_running))
145 return;
146
147 runtime = isight->pcm->runtime;
148 dropped = total - isight->total_samples;
149 if (dropped < runtime->buffer_size) {
150 if (isight->buffer_pointer + dropped <= runtime->buffer_size) {
151 memset(runtime->dma_area + isight->buffer_pointer * 4,
152 0, dropped * 4);
153 } else {
154 count1 = runtime->buffer_size - isight->buffer_pointer;
155 memset(runtime->dma_area + isight->buffer_pointer * 4,
156 0, count1 * 4);
157 memset(runtime->dma_area, 0, (dropped - count1) * 4);
158 }
159 isight_update_pointers(isight, count: dropped);
160 } else {
161 isight_pcm_abort(isight);
162 }
163}
164
165static void isight_packet(struct fw_iso_context *context, u32 cycle,
166 size_t header_length, void *header, void *data)
167{
168 struct isight *isight = data;
169 const struct audio_payload *payload;
170 unsigned int index, length, count, total;
171 int err;
172
173 if (isight->packet_index < 0)
174 return;
175 index = isight->packet_index;
176 payload = isight->buffer.packets[index].buffer;
177 length = be32_to_cpup(p: header) >> 16;
178
179 if (likely(length >= 16 &&
180 payload->signature == cpu_to_be32(0x73676874/*"sght"*/))) {
181 count = be32_to_cpu(payload->sample_count);
182 if (likely(count <= (length - 16) / 4)) {
183 total = be32_to_cpu(payload->sample_total);
184 if (unlikely(total != isight->total_samples)) {
185 if (!isight->first_packet)
186 isight_dropped_samples(isight, total);
187 isight->first_packet = false;
188 isight->total_samples = total;
189 }
190
191 isight_samples(isight, samples: payload->samples, count);
192 isight->total_samples += count;
193 }
194 }
195
196 err = fw_iso_context_queue(ctx: isight->context, packet: &audio_packet,
197 buffer: &isight->buffer.iso_buffer,
198 payload: isight->buffer.packets[index].offset);
199 if (err < 0) {
200 dev_err(&isight->unit->device, "queueing error: %d\n", err);
201 isight_pcm_abort(isight);
202 isight->packet_index = -1;
203 return;
204 }
205 fw_iso_context_queue_flush(ctx: isight->context);
206
207 if (++index >= QUEUE_LENGTH)
208 index = 0;
209 isight->packet_index = index;
210}
211
212static int isight_connect(struct isight *isight)
213{
214 int ch, err;
215 __be32 value;
216
217retry_after_bus_reset:
218 ch = fw_iso_resources_allocate(r: &isight->resources,
219 max_payload_bytes: sizeof(struct audio_payload),
220 speed: isight->device->max_speed);
221 if (ch < 0) {
222 err = ch;
223 goto error;
224 }
225
226 value = cpu_to_be32(ch | (isight->device->max_speed << SPEED_SHIFT));
227 err = snd_fw_transaction(unit: isight->unit, TCODE_WRITE_QUADLET_REQUEST,
228 offset: isight->audio_base + REG_ISO_TX_CONFIG,
229 buffer: &value, length: 4, FW_FIXED_GENERATION |
230 isight->resources.generation);
231 if (err == -EAGAIN) {
232 fw_iso_resources_free(r: &isight->resources);
233 goto retry_after_bus_reset;
234 } else if (err < 0) {
235 goto err_resources;
236 }
237
238 return 0;
239
240err_resources:
241 fw_iso_resources_free(r: &isight->resources);
242error:
243 return err;
244}
245
246static int isight_open(struct snd_pcm_substream *substream)
247{
248 static const struct snd_pcm_hardware hardware = {
249 .info = SNDRV_PCM_INFO_MMAP |
250 SNDRV_PCM_INFO_MMAP_VALID |
251 SNDRV_PCM_INFO_BATCH |
252 SNDRV_PCM_INFO_INTERLEAVED |
253 SNDRV_PCM_INFO_BLOCK_TRANSFER,
254 .formats = SNDRV_PCM_FMTBIT_S16_BE,
255 .rates = SNDRV_PCM_RATE_48000,
256 .rate_min = 48000,
257 .rate_max = 48000,
258 .channels_min = 2,
259 .channels_max = 2,
260 .buffer_bytes_max = 4 * 1024 * 1024,
261 .period_bytes_min = MAX_FRAMES_PER_PACKET * 4,
262 .period_bytes_max = 1024 * 1024,
263 .periods_min = 2,
264 .periods_max = UINT_MAX,
265 };
266 struct isight *isight = substream->private_data;
267
268 substream->runtime->hw = hardware;
269
270 return iso_packets_buffer_init(b: &isight->buffer, unit: isight->unit,
271 QUEUE_LENGTH,
272 packet_size: sizeof(struct audio_payload),
273 direction: DMA_FROM_DEVICE);
274}
275
276static int isight_close(struct snd_pcm_substream *substream)
277{
278 struct isight *isight = substream->private_data;
279
280 iso_packets_buffer_destroy(b: &isight->buffer, unit: isight->unit);
281
282 return 0;
283}
284
285static int isight_hw_params(struct snd_pcm_substream *substream,
286 struct snd_pcm_hw_params *hw_params)
287{
288 struct isight *isight = substream->private_data;
289
290 WRITE_ONCE(isight->pcm_active, true);
291
292 return 0;
293}
294
295static int reg_read(struct isight *isight, int offset, __be32 *value)
296{
297 return snd_fw_transaction(unit: isight->unit, TCODE_READ_QUADLET_REQUEST,
298 offset: isight->audio_base + offset, buffer: value, length: 4, flags: 0);
299}
300
301static int reg_write(struct isight *isight, int offset, __be32 value)
302{
303 return snd_fw_transaction(unit: isight->unit, TCODE_WRITE_QUADLET_REQUEST,
304 offset: isight->audio_base + offset, buffer: &value, length: 4, flags: 0);
305}
306
307static void isight_stop_streaming(struct isight *isight)
308{
309 __be32 value;
310
311 if (!isight->context)
312 return;
313
314 fw_iso_context_stop(ctx: isight->context);
315 fw_iso_context_destroy(ctx: isight->context);
316 isight->context = NULL;
317 fw_iso_resources_free(r: &isight->resources);
318 value = 0;
319 snd_fw_transaction(unit: isight->unit, TCODE_WRITE_QUADLET_REQUEST,
320 offset: isight->audio_base + REG_AUDIO_ENABLE,
321 buffer: &value, length: 4, FW_QUIET);
322}
323
324static int isight_hw_free(struct snd_pcm_substream *substream)
325{
326 struct isight *isight = substream->private_data;
327
328 WRITE_ONCE(isight->pcm_active, false);
329
330 mutex_lock(&isight->mutex);
331 isight_stop_streaming(isight);
332 mutex_unlock(lock: &isight->mutex);
333
334 return 0;
335}
336
337static int isight_start_streaming(struct isight *isight)
338{
339 unsigned int i;
340 int err;
341
342 if (isight->context) {
343 if (isight->packet_index < 0)
344 isight_stop_streaming(isight);
345 else
346 return 0;
347 }
348
349 err = reg_write(isight, REG_SAMPLE_RATE, cpu_to_be32(RATE_48000));
350 if (err < 0)
351 goto error;
352
353 err = isight_connect(isight);
354 if (err < 0)
355 goto error;
356
357 err = reg_write(isight, REG_AUDIO_ENABLE, cpu_to_be32(AUDIO_ENABLE));
358 if (err < 0)
359 goto err_resources;
360
361 isight->context = fw_iso_context_create(card: isight->device->card,
362 FW_ISO_CONTEXT_RECEIVE,
363 channel: isight->resources.channel,
364 speed: isight->device->max_speed,
365 header_size: 4, callback: isight_packet, callback_data: isight);
366 if (IS_ERR(ptr: isight->context)) {
367 err = PTR_ERR(ptr: isight->context);
368 isight->context = NULL;
369 goto err_resources;
370 }
371
372 for (i = 0; i < QUEUE_LENGTH; ++i) {
373 err = fw_iso_context_queue(ctx: isight->context, packet: &audio_packet,
374 buffer: &isight->buffer.iso_buffer,
375 payload: isight->buffer.packets[i].offset);
376 if (err < 0)
377 goto err_context;
378 }
379
380 isight->first_packet = true;
381 isight->packet_index = 0;
382
383 err = fw_iso_context_start(ctx: isight->context, cycle: -1, sync: 0,
384 FW_ISO_CONTEXT_MATCH_ALL_TAGS/*?*/);
385 if (err < 0)
386 goto err_context;
387
388 return 0;
389
390err_context:
391 fw_iso_context_destroy(ctx: isight->context);
392 isight->context = NULL;
393err_resources:
394 fw_iso_resources_free(r: &isight->resources);
395 reg_write(isight, REG_AUDIO_ENABLE, value: 0);
396error:
397 return err;
398}
399
400static int isight_prepare(struct snd_pcm_substream *substream)
401{
402 struct isight *isight = substream->private_data;
403 int err;
404
405 isight->buffer_pointer = 0;
406 isight->period_counter = 0;
407
408 mutex_lock(&isight->mutex);
409 err = isight_start_streaming(isight);
410 mutex_unlock(lock: &isight->mutex);
411
412 return err;
413}
414
415static int isight_trigger(struct snd_pcm_substream *substream, int cmd)
416{
417 struct isight *isight = substream->private_data;
418
419 switch (cmd) {
420 case SNDRV_PCM_TRIGGER_START:
421 WRITE_ONCE(isight->pcm_running, true);
422 break;
423 case SNDRV_PCM_TRIGGER_STOP:
424 WRITE_ONCE(isight->pcm_running, false);
425 break;
426 default:
427 return -EINVAL;
428 }
429 return 0;
430}
431
432static snd_pcm_uframes_t isight_pointer(struct snd_pcm_substream *substream)
433{
434 struct isight *isight = substream->private_data;
435
436 return READ_ONCE(isight->buffer_pointer);
437}
438
439static int isight_create_pcm(struct isight *isight)
440{
441 static const struct snd_pcm_ops ops = {
442 .open = isight_open,
443 .close = isight_close,
444 .hw_params = isight_hw_params,
445 .hw_free = isight_hw_free,
446 .prepare = isight_prepare,
447 .trigger = isight_trigger,
448 .pointer = isight_pointer,
449 };
450 struct snd_pcm *pcm;
451 int err;
452
453 err = snd_pcm_new(card: isight->card, id: "iSight", device: 0, playback_count: 0, capture_count: 1, rpcm: &pcm);
454 if (err < 0)
455 return err;
456 pcm->private_data = isight;
457 strcpy(p: pcm->name, q: "iSight");
458 isight->pcm = pcm->streams[SNDRV_PCM_STREAM_CAPTURE].substream;
459 isight->pcm->ops = &ops;
460 snd_pcm_set_managed_buffer_all(pcm, SNDRV_DMA_TYPE_VMALLOC, NULL, size: 0, max: 0);
461
462 return 0;
463}
464
465static int isight_gain_info(struct snd_kcontrol *ctl,
466 struct snd_ctl_elem_info *info)
467{
468 struct isight *isight = ctl->private_data;
469
470 info->type = SNDRV_CTL_ELEM_TYPE_INTEGER;
471 info->count = 1;
472 info->value.integer.min = isight->gain_min;
473 info->value.integer.max = isight->gain_max;
474
475 return 0;
476}
477
478static int isight_gain_get(struct snd_kcontrol *ctl,
479 struct snd_ctl_elem_value *value)
480{
481 struct isight *isight = ctl->private_data;
482 __be32 gain;
483 int err;
484
485 err = reg_read(isight, REG_GAIN, value: &gain);
486 if (err < 0)
487 return err;
488
489 value->value.integer.value[0] = (s32)be32_to_cpu(gain);
490
491 return 0;
492}
493
494static int isight_gain_put(struct snd_kcontrol *ctl,
495 struct snd_ctl_elem_value *value)
496{
497 struct isight *isight = ctl->private_data;
498
499 if (value->value.integer.value[0] < isight->gain_min ||
500 value->value.integer.value[0] > isight->gain_max)
501 return -EINVAL;
502
503 return reg_write(isight, REG_GAIN,
504 cpu_to_be32(value->value.integer.value[0]));
505}
506
507static int isight_mute_get(struct snd_kcontrol *ctl,
508 struct snd_ctl_elem_value *value)
509{
510 struct isight *isight = ctl->private_data;
511 __be32 mute;
512 int err;
513
514 err = reg_read(isight, REG_MUTE, value: &mute);
515 if (err < 0)
516 return err;
517
518 value->value.integer.value[0] = !mute;
519
520 return 0;
521}
522
523static int isight_mute_put(struct snd_kcontrol *ctl,
524 struct snd_ctl_elem_value *value)
525{
526 struct isight *isight = ctl->private_data;
527
528 return reg_write(isight, REG_MUTE,
529 value: (__force __be32)!value->value.integer.value[0]);
530}
531
532static int isight_create_mixer(struct isight *isight)
533{
534 static const struct snd_kcontrol_new gain_control = {
535 .iface = SNDRV_CTL_ELEM_IFACE_MIXER,
536 .name = "Mic Capture Volume",
537 .access = SNDRV_CTL_ELEM_ACCESS_READWRITE |
538 SNDRV_CTL_ELEM_ACCESS_TLV_READ,
539 .info = isight_gain_info,
540 .get = isight_gain_get,
541 .put = isight_gain_put,
542 };
543 static const struct snd_kcontrol_new mute_control = {
544 .iface = SNDRV_CTL_ELEM_IFACE_MIXER,
545 .name = "Mic Capture Switch",
546 .info = snd_ctl_boolean_mono_info,
547 .get = isight_mute_get,
548 .put = isight_mute_put,
549 };
550 __be32 value;
551 struct snd_kcontrol *ctl;
552 int err;
553
554 err = reg_read(isight, REG_GAIN_RAW_START, value: &value);
555 if (err < 0)
556 return err;
557 isight->gain_min = be32_to_cpu(value);
558
559 err = reg_read(isight, REG_GAIN_RAW_END, value: &value);
560 if (err < 0)
561 return err;
562 isight->gain_max = be32_to_cpu(value);
563
564 isight->gain_tlv[SNDRV_CTL_TLVO_TYPE] = SNDRV_CTL_TLVT_DB_MINMAX;
565 isight->gain_tlv[SNDRV_CTL_TLVO_LEN] = 2 * sizeof(unsigned int);
566
567 err = reg_read(isight, REG_GAIN_DB_START, value: &value);
568 if (err < 0)
569 return err;
570 isight->gain_tlv[SNDRV_CTL_TLVO_DB_MINMAX_MIN] =
571 (s32)be32_to_cpu(value) * 100;
572
573 err = reg_read(isight, REG_GAIN_DB_END, value: &value);
574 if (err < 0)
575 return err;
576 isight->gain_tlv[SNDRV_CTL_TLVO_DB_MINMAX_MAX] =
577 (s32)be32_to_cpu(value) * 100;
578
579 ctl = snd_ctl_new1(kcontrolnew: &gain_control, private_data: isight);
580 if (ctl)
581 ctl->tlv.p = isight->gain_tlv;
582 err = snd_ctl_add(card: isight->card, kcontrol: ctl);
583 if (err < 0)
584 return err;
585
586 err = snd_ctl_add(card: isight->card, kcontrol: snd_ctl_new1(kcontrolnew: &mute_control, private_data: isight));
587 if (err < 0)
588 return err;
589
590 return 0;
591}
592
593static void isight_card_free(struct snd_card *card)
594{
595 struct isight *isight = card->private_data;
596
597 fw_iso_resources_destroy(r: &isight->resources);
598}
599
600static u64 get_unit_base(struct fw_unit *unit)
601{
602 struct fw_csr_iterator i;
603 int key, value;
604
605 fw_csr_iterator_init(ci: &i, p: unit->directory);
606 while (fw_csr_iterator_next(ci: &i, key: &key, value: &value))
607 if (key == CSR_OFFSET)
608 return CSR_REGISTER_BASE + value * 4;
609 return 0;
610}
611
612static int isight_probe(struct fw_unit *unit,
613 const struct ieee1394_device_id *id)
614{
615 struct fw_device *fw_dev = fw_parent_device(unit);
616 struct snd_card *card;
617 struct isight *isight;
618 int err;
619
620 err = snd_card_new(parent: &unit->device, idx: -1, NULL, THIS_MODULE,
621 extra_size: sizeof(*isight), card_ret: &card);
622 if (err < 0)
623 return err;
624
625 isight = card->private_data;
626 isight->card = card;
627 mutex_init(&isight->mutex);
628 isight->unit = fw_unit_get(unit);
629 isight->device = fw_dev;
630 isight->audio_base = get_unit_base(unit);
631 if (!isight->audio_base) {
632 dev_err(&unit->device, "audio unit base not found\n");
633 err = -ENXIO;
634 goto error;
635 }
636 fw_iso_resources_init(r: &isight->resources, unit);
637
638 card->private_free = isight_card_free;
639
640 strcpy(p: card->driver, q: "iSight");
641 strcpy(p: card->shortname, q: "Apple iSight");
642 snprintf(buf: card->longname, size: sizeof(card->longname),
643 fmt: "Apple iSight (GUID %08x%08x) at %s, S%d",
644 fw_dev->config_rom[3], fw_dev->config_rom[4],
645 dev_name(dev: &unit->device), 100 << fw_dev->max_speed);
646 strcpy(p: card->mixername, q: "iSight");
647
648 err = isight_create_pcm(isight);
649 if (err < 0)
650 goto error;
651
652 err = isight_create_mixer(isight);
653 if (err < 0)
654 goto error;
655
656 err = snd_card_register(card);
657 if (err < 0)
658 goto error;
659
660 dev_set_drvdata(dev: &unit->device, data: isight);
661
662 return 0;
663error:
664 snd_card_free(card);
665
666 mutex_destroy(lock: &isight->mutex);
667 fw_unit_put(unit: isight->unit);
668
669 return err;
670}
671
672static void isight_bus_reset(struct fw_unit *unit)
673{
674 struct isight *isight = dev_get_drvdata(dev: &unit->device);
675
676 if (fw_iso_resources_update(r: &isight->resources) < 0) {
677 isight_pcm_abort(isight);
678
679 mutex_lock(&isight->mutex);
680 isight_stop_streaming(isight);
681 mutex_unlock(lock: &isight->mutex);
682 }
683}
684
685static void isight_remove(struct fw_unit *unit)
686{
687 struct isight *isight = dev_get_drvdata(dev: &unit->device);
688
689 isight_pcm_abort(isight);
690
691 snd_card_disconnect(card: isight->card);
692
693 mutex_lock(&isight->mutex);
694 isight_stop_streaming(isight);
695 mutex_unlock(lock: &isight->mutex);
696
697 // Block till all of ALSA character devices are released.
698 snd_card_free(card: isight->card);
699
700 mutex_destroy(lock: &isight->mutex);
701 fw_unit_put(unit: isight->unit);
702}
703
704static const struct ieee1394_device_id isight_id_table[] = {
705 {
706 .match_flags = IEEE1394_MATCH_SPECIFIER_ID |
707 IEEE1394_MATCH_VERSION,
708 .specifier_id = OUI_APPLE,
709 .version = SW_ISIGHT_AUDIO,
710 },
711 { }
712};
713MODULE_DEVICE_TABLE(ieee1394, isight_id_table);
714
715static struct fw_driver isight_driver = {
716 .driver = {
717 .owner = THIS_MODULE,
718 .name = KBUILD_MODNAME,
719 .bus = &fw_bus_type,
720 },
721 .probe = isight_probe,
722 .update = isight_bus_reset,
723 .remove = isight_remove,
724 .id_table = isight_id_table,
725};
726
727static int __init alsa_isight_init(void)
728{
729 return driver_register(drv: &isight_driver.driver);
730}
731
732static void __exit alsa_isight_exit(void)
733{
734 driver_unregister(drv: &isight_driver.driver);
735}
736
737module_init(alsa_isight_init);
738module_exit(alsa_isight_exit);
739

source code of linux/sound/firewire/isight.c