pcm.c

linux 内核源代码

	if (pcm->private_free)
		pcm->private_free(pcm);
	snd_pcm_lib_preallocate_free_for_all(pcm);
	snd_pcm_free_stream(&pcm->streams[SNDRV_PCM_STREAM_PLAYBACK]);
	snd_pcm_free_stream(&pcm->streams[SNDRV_PCM_STREAM_CAPTURE]);
	kfree(pcm);
	return 0;
}

static int snd_pcm_dev_free(struct snd_device *device)
{
	struct snd_pcm *pcm = device->device_data;
	return snd_pcm_free(pcm);
}

static void snd_pcm_tick_timer_func(unsigned long data)
{
	struct snd_pcm_substream *substream = (struct snd_pcm_substream *) data;
	snd_pcm_tick_elapsed(substream);
}

int snd_pcm_attach_substream(struct snd_pcm *pcm, int stream,
			     struct file *file,
			     struct snd_pcm_substream **rsubstream)
{
	struct snd_pcm_str * pstr;
	struct snd_pcm_substream *substream;
	struct snd_pcm_runtime *runtime;
	struct snd_ctl_file *kctl;
	struct snd_card *card;
	int prefer_subdevice = -1;
	size_t size;

	snd_assert(rsubstream != NULL, return -EINVAL);
	*rsubstream = NULL;
	snd_assert(pcm != NULL, return -ENXIO);
	pstr = &pcm->streams[stream];
	if (pstr->substream == NULL || pstr->substream_count == 0)
		return -ENODEV;

	card = pcm->card;
	down_read(&card->controls_rwsem);
	list_for_each_entry(kctl, &card->ctl_files, list) {
		if (kctl->pid == current->pid) {
			prefer_subdevice = kctl->prefer_pcm_subdevice;
			if (prefer_subdevice != -1)
				break;
		}
	}
	up_read(&card->controls_rwsem);

	switch (stream) {
	case SNDRV_PCM_STREAM_PLAYBACK:
		if (pcm->info_flags & SNDRV_PCM_INFO_HALF_DUPLEX) {
			for (substream = pcm->streams[SNDRV_PCM_STREAM_CAPTURE].substream; substream; substream = substream->next) {
				if (SUBSTREAM_BUSY(substream))
					return -EAGAIN;
			}
		}
		break;
	case SNDRV_PCM_STREAM_CAPTURE:
		if (pcm->info_flags & SNDRV_PCM_INFO_HALF_DUPLEX) {
			for (substream = pcm->streams[SNDRV_PCM_STREAM_PLAYBACK].substream; substream; substream = substream->next) {
				if (SUBSTREAM_BUSY(substream))
					return -EAGAIN;
			}
		}
		break;
	default:
		return -EINVAL;
	}

	if (file->f_flags & O_APPEND) {
		if (prefer_subdevice < 0) {
			if (pstr->substream_count > 1)
				return -EINVAL; /* must be unique */
			substream = pstr->substream;
		} else {
			for (substream = pstr->substream; substream;
			     substream = substream->next)
				if (substream->number == prefer_subdevice)
					break;
		}
		if (! substream)
			return -ENODEV;
		if (! SUBSTREAM_BUSY(substream))
			return -EBADFD;
		substream->ref_count++;
		*rsubstream = substream;
		return 0;
	}

	if (prefer_subdevice >= 0) {
		for (substream = pstr->substream; substream; substream = substream->next)
			if (!SUBSTREAM_BUSY(substream) && substream->number == prefer_subdevice)
				goto __ok;
	}
	for (substream = pstr->substream; substream; substream = substream->next)
		if (!SUBSTREAM_BUSY(substream))
			break;
      __ok:
	if (substream == NULL)
		return -EAGAIN;

	runtime = kzalloc(sizeof(*runtime), GFP_KERNEL);
	if (runtime == NULL)
		return -ENOMEM;

	size = PAGE_ALIGN(sizeof(struct snd_pcm_mmap_status));
	runtime->status = snd_malloc_pages(size, GFP_KERNEL);
	if (runtime->status == NULL) {
		kfree(runtime);
		return -ENOMEM;
	}
	memset((void*)runtime->status, 0, size);

	size = PAGE_ALIGN(sizeof(struct snd_pcm_mmap_control));
	runtime->control = snd_malloc_pages(size, GFP_KERNEL);
	if (runtime->control == NULL) {
		snd_free_pages((void*)runtime->status,
			       PAGE_ALIGN(sizeof(struct snd_pcm_mmap_status)));
		kfree(runtime);
		return -ENOMEM;
	}
	memset((void*)runtime->control, 0, size);

	init_waitqueue_head(&runtime->sleep);
	init_timer(&runtime->tick_timer);
	runtime->tick_timer.function = snd_pcm_tick_timer_func;
	runtime->tick_timer.data = (unsigned long) substream;

	runtime->status->state = SNDRV_PCM_STATE_OPEN;

	substream->runtime = runtime;
	substream->private_data = pcm->private_data;
	substream->ref_count = 1;
	substream->f_flags = file->f_flags;
	pstr->substream_opened++;
	*rsubstream = substream;
	return 0;
}

void snd_pcm_detach_substream(struct snd_pcm_substream *substream)
{
	struct snd_pcm_runtime *runtime;

	runtime = substream->runtime;
	snd_assert(runtime != NULL, return);
	if (runtime->private_free != NULL)
		runtime->private_free(runtime);
	snd_free_pages((void*)runtime->status,
		       PAGE_ALIGN(sizeof(struct snd_pcm_mmap_status)));
	snd_free_pages((void*)runtime->control,
		       PAGE_ALIGN(sizeof(struct snd_pcm_mmap_control)));
	kfree(runtime->hw_constraints.rules);
	kfree(runtime);
	substream->runtime = NULL;
	substream->pstr->substream_opened--;
}

static ssize_t show_pcm_class(struct device *dev,
			      struct device_attribute *attr, char *buf)
{
	struct snd_pcm *pcm;
	const char *str;
	static const char *strs[SNDRV_PCM_CLASS_LAST + 1] = {
		[SNDRV_PCM_CLASS_GENERIC] = "generic",
		[SNDRV_PCM_CLASS_MULTI] = "multi",
		[SNDRV_PCM_CLASS_MODEM] = "modem",
		[SNDRV_PCM_CLASS_DIGITIZER] = "digitizer",
	};

	if (! (pcm = dev_get_drvdata(dev)) ||
	    pcm->dev_class > SNDRV_PCM_CLASS_LAST)
		str = "none";
	else
		str = strs[pcm->dev_class];
        return snprintf(buf, PAGE_SIZE, "%s\n", str);
}

static struct device_attribute pcm_attrs =
	__ATTR(pcm_class, S_IRUGO, show_pcm_class, NULL);

static int snd_pcm_dev_register(struct snd_device *device)
{
	int cidx, err;
	struct snd_pcm_substream *substream;
	struct snd_pcm_notify *notify;
	char str[16];
	struct snd_pcm *pcm = device->device_data;
	struct device *dev;

	snd_assert(pcm != NULL && device != NULL, return -ENXIO);
	mutex_lock(&register_mutex);
	if (snd_pcm_search(pcm->card, pcm->device)) {
		mutex_unlock(&register_mutex);
		return -EBUSY;
	}
	list_add_tail(&pcm->list, &snd_pcm_devices);
	for (cidx = 0; cidx < 2; cidx++) {
		int devtype = -1;
		if (pcm->streams[cidx].substream == NULL)
			continue;
		switch (cidx) {
		case SNDRV_PCM_STREAM_PLAYBACK:
			sprintf(str, "pcmC%iD%ip", pcm->card->number, pcm->device);
			devtype = SNDRV_DEVICE_TYPE_PCM_PLAYBACK;
			break;
		case SNDRV_PCM_STREAM_CAPTURE:
			sprintf(str, "pcmC%iD%ic", pcm->card->number, pcm->device);
			devtype = SNDRV_DEVICE_TYPE_PCM_CAPTURE;
			break;
		}
		/* device pointer to use, pcm->dev takes precedence if
		 * it is assigned, otherwise fall back to card's device
		 * if possible */
		dev = pcm->dev;
		if (!dev)
			dev = snd_card_get_device_link(pcm->card);
		/* register pcm */
		err = snd_register_device_for_dev(devtype, pcm->card,
						  pcm->device,
						  &snd_pcm_f_ops[cidx],
						  pcm, str, dev);
		if (err < 0) {
			list_del(&pcm->list);
			mutex_unlock(&register_mutex);
			return err;
		}
		snd_add_device_sysfs_file(devtype, pcm->card, pcm->device,
					  &pcm_attrs);
		for (substream = pcm->streams[cidx].substream; substream; substream = substream->next)
			snd_pcm_timer_init(substream);
	}

	list_for_each_entry(notify, &snd_pcm_notify_list, list)
		notify->n_register(pcm);

	mutex_unlock(&register_mutex);
	return 0;
}

static int snd_pcm_dev_disconnect(struct snd_device *device)
{
	struct snd_pcm *pcm = device->device_data;
	struct snd_pcm_notify *notify;
	struct snd_pcm_substream *substream;
	int cidx, devtype;

	mutex_lock(&register_mutex);
	if (list_empty(&pcm->list))
		goto unlock;

	list_del_init(&pcm->list);
	for (cidx = 0; cidx < 2; cidx++)
		for (substream = pcm->streams[cidx].substream; substream; substream = substream->next)
			if (substream->runtime)
				substream->runtime->status->state = SNDRV_PCM_STATE_DISCONNECTED;
	list_for_each_entry(notify, &snd_pcm_notify_list, list) {
		notify->n_disconnect(pcm);
	}
	for (cidx = 0; cidx < 2; cidx++) {
		devtype = -1;
		switch (cidx) {
		case SNDRV_PCM_STREAM_PLAYBACK:
			devtype = SNDRV_DEVICE_TYPE_PCM_PLAYBACK;
			break;
		case SNDRV_PCM_STREAM_CAPTURE:
			devtype = SNDRV_DEVICE_TYPE_PCM_CAPTURE;
			break;
		}
		snd_unregister_device(devtype, pcm->card, pcm->device);
	}
 unlock:
	mutex_unlock(&register_mutex);
	return 0;
}

int snd_pcm_notify(struct snd_pcm_notify *notify, int nfree)
{
	struct snd_pcm *pcm;

	snd_assert(notify != NULL &&
		   notify->n_register != NULL &&
		   notify->n_unregister != NULL &&
		   notify->n_disconnect, return -EINVAL);
	mutex_lock(&register_mutex);
	if (nfree) {
		list_del(&notify->list);
		list_for_each_entry(pcm, &snd_pcm_devices, list)
			notify->n_unregister(pcm);
	} else {
		list_add_tail(&notify->list, &snd_pcm_notify_list);
		list_for_each_entry(pcm, &snd_pcm_devices, list)
			notify->n_register(pcm);
	}
	mutex_unlock(&register_mutex);
	return 0;
}

EXPORT_SYMBOL(snd_pcm_notify);

#ifdef CONFIG_PROC_FS
/*
 *  Info interface
 */

static void snd_pcm_proc_read(struct snd_info_entry *entry,
			      struct snd_info_buffer *buffer)
{
	struct snd_pcm *pcm;

	mutex_lock(&register_mutex);
	list_for_each_entry(pcm, &snd_pcm_devices, list) {
		snd_iprintf(buffer, "%02i-%02i: %s : %s",
			    pcm->card->number, pcm->device, pcm->id, pcm->name);
		if (pcm->streams[SNDRV_PCM_STREAM_PLAYBACK].substream)
			snd_iprintf(buffer, " : playback %i",
				    pcm->streams[SNDRV_PCM_STREAM_PLAYBACK].substream_count);
		if (pcm->streams[SNDRV_PCM_STREAM_CAPTURE].substream)
			snd_iprintf(buffer, " : capture %i",
				    pcm->streams[SNDRV_PCM_STREAM_CAPTURE].substream_count);
		snd_iprintf(buffer, "\n");
	}
	mutex_unlock(&register_mutex);
}

static struct snd_info_entry *snd_pcm_proc_entry;

static void snd_pcm_proc_init(void)
{
	struct snd_info_entry *entry;

	if ((entry = snd_info_create_module_entry(THIS_MODULE, "pcm", NULL)) != NULL) {
		snd_info_set_text_ops(entry, NULL, snd_pcm_proc_read);
		if (snd_info_register(entry) < 0) {
			snd_info_free_entry(entry);
			entry = NULL;
		}
	}
	snd_pcm_proc_entry = entry;
}

static void snd_pcm_proc_done(void)
{
	snd_info_free_entry(snd_pcm_proc_entry);
}

#else /* !CONFIG_PROC_FS */
#define snd_pcm_proc_init()
#define snd_pcm_proc_done()
#endif /* CONFIG_PROC_FS */


/*
 *  ENTRY functions
 */

static int __init alsa_pcm_init(void)
{
	snd_ctl_register_ioctl(snd_pcm_control_ioctl);
	snd_ctl_register_ioctl_compat(snd_pcm_control_ioctl);
	snd_pcm_proc_init();
	return 0;
}

static void __exit alsa_pcm_exit(void)
{
	snd_ctl_unregister_ioctl(snd_pcm_control_ioctl);
	snd_ctl_unregister_ioctl_compat(snd_pcm_control_ioctl);
	snd_pcm_proc_done();
}

module_init(alsa_pcm_init)
module_exit(alsa_pcm_exit)