path: root/sound/usb/pcm.c

// SPDX-License-Identifier: GPL-2.0-or-later
/*
 */

#include <linux/init.h>
#include <linux/slab.h>
#include <linux/bitrev.h>
#include <linux/ratelimit.h>
#include <linux/usb.h>
#include <linux/usb/audio.h>
#include <linux/usb/audio-v2.h>

#include <sound/core.h>
#include <sound/pcm.h>
#include <sound/pcm_params.h>

#include "usbaudio.h"
#include "card.h"
#include "quirks.h"
#include "endpoint.h"
#include "helper.h"
#include "pcm.h"
#include "clock.h"
#include "power.h"
#include "media.h"
#include "implicit.h"

#define SUBSTREAM_FLAG_DATA_EP_STARTED	0
#define SUBSTREAM_FLAG_SYNC_EP_STARTED	1

/* return the estimated delay based on USB frame counters */
snd_pcm_uframes_t snd_usb_pcm_delay(struct snd_usb_substream *subs,
				    unsigned int rate)
{
	int current_frame_number;
	int frame_diff;
	int est_delay;

	if (!subs->last_delay)
		return 0; /* short path */

	current_frame_number = usb_get_current_frame_number(subs->dev);
	/*
	 * HCD implementations use different widths, use lower 8 bits.
	 * The delay will be managed up to 256ms, which is more than
	 * enough
	 */
	frame_diff = (current_frame_number - subs->last_frame_number) & 0xff;

	/* Approximation based on number of samples per USB frame (ms),
	   some truncation for 44.1 but the estimate is good enough */
	est_delay =  frame_diff * rate / 1000;
	if (subs->direction == SNDRV_PCM_STREAM_PLAYBACK)
		est_delay = subs->last_delay - est_delay;
	else
		est_delay = subs->last_delay + est_delay;

	if (est_delay < 0)
		est_delay = 0;
	return est_delay;
}

/*
 * return the current pcm pointer.  just based on the hwptr_done value.
 */
static snd_pcm_uframes_t snd_usb_pcm_pointer(struct snd_pcm_substream *substream)
{
	struct snd_usb_substream *subs = substream->runtime->private_data;
	unsigned int hwptr_done;

	if (atomic_read(&subs->stream->chip->shutdown))
		return SNDRV_PCM_POS_XRUN;
	spin_lock(&subs->lock);
	hwptr_done = subs->hwptr_done;
	substream->runtime->delay = snd_usb_pcm_delay(subs,
						substream->runtime->rate);
	spin_unlock(&subs->lock);
	return hwptr_done / (substream->runtime->frame_bits >> 3);
}

/*
 * find a matching audio format
 */
static const struct audioformat *
find_format(struct list_head *fmt_list_head, snd_pcm_format_t format,
	    unsigned int rate, unsigned int channels, bool strict_match,
	    struct snd_usb_substream *subs)
{
	const struct audioformat *fp;
	const struct audioformat *found = NULL;
	int cur_attr = 0, attr;

	list_for_each_entry(fp, fmt_list_head, list) {
		if (strict_match) {
			if (!(fp->formats & pcm_format_to_bits(format)))
				continue;
			if (fp->channels != channels)
				continue;
		}
		if (rate < fp->rate_min || rate > fp->rate_max)
			continue;
		if (!(fp->rates & SNDRV_PCM_RATE_CONTINUOUS)) {
			unsigned int i;
			for (i = 0; i < fp->nr_rates; i++)
				if (fp->rate_table[i] == rate)
					break;
			if (i >= fp->nr_rates)
				continue;
		}
		attr = fp->ep_attr & USB_ENDPOINT_SYNCTYPE;
		if (!found) {
			found = fp;
			cur_attr = attr;
			continue;
		}
		/* avoid async out and adaptive in if the other method
		 * supports the same format.
		 * this is a workaround for the case like
		 * M-audio audiophile USB.
		 */
		if (subs && attr != cur_attr) {
			if ((attr == USB_ENDPOINT_SYNC_ASYNC &&
			     subs->direction == SNDRV_PCM_STREAM_PLAYBACK) ||
			    (attr == USB_ENDPOINT_SYNC_ADAPTIVE &&
			     subs->direction == SNDRV_PCM_STREAM_CAPTURE))
				continue;
			if ((cur_attr == USB_ENDPOINT_SYNC_ASYNC &&
			     subs->direction == SNDRV_PCM_STREAM_PLAYBACK) ||
			    (cur_attr == USB_ENDPOINT_SYNC_ADAPTIVE &&
			     subs->direction == SNDRV_PCM_STREAM_CAPTURE)) {
				found = fp;
				cur_attr = attr;
				continue;
			}
		}
		/* find the format with the largest max. packet size */
		if (fp->maxpacksize > found->maxpacksize) {
			found = fp;
			cur_attr = attr;
		}
	}
	return found;
}

static const struct audioformat *
find_substream_format(struct snd_usb_substream *subs,
		      const struct snd_pcm_hw_params *params)
{
	return find_format(&subs->fmt_list, params_format(params),
			   params_rate(params), params_channels(params),
			   true, subs);
}

static int init_pitch_v1(struct snd_usb_audio *chip, int ep)
{
	struct usb_device *dev = chip->dev;
	unsigned char data[1];
	int err;

	data[0] = 1;
	err = snd_usb_ctl_msg(dev, usb_sndctrlpipe(dev, 0), UAC_SET_CUR,
			      USB_TYPE_CLASS|USB_RECIP_ENDPOINT|USB_DIR_OUT,
			      UAC_EP_CS_ATTR_PITCH_CONTROL << 8, ep,
			      data, sizeof(data));
	return err;
}

static int init_pitch_v2(struct snd_usb_audio *chip, int ep)
{
	struct usb_device *dev = chip->dev;
	unsigned char data[1];
	int err;

	data[0] = 1;
	err = snd_usb_ctl_msg(dev, usb_sndctrlpipe(dev, 0), UAC2_CS_CUR,
			      USB_TYPE_CLASS | USB_RECIP_ENDPOINT | USB_DIR_OUT,
			      UAC2_EP_CS_PITCH << 8, 0,
			      data, sizeof(data));
	return err;
}

/*
 * initialize the pitch control and sample rate
 */
int snd_usb_init_pitch(struct snd_usb_audio *chip,
		       const struct audioformat *fmt)
{
	int err;

	/* if endpoint doesn't have pitch control, bail out */
	if (!(fmt->attributes & UAC_EP_CS_ATTR_PITCH_CONTROL))
		return 0;

	usb_audio_dbg(chip, "enable PITCH for EP 0x%x\n", fmt->endpoint);

	switch (fmt->protocol) {
	case UAC_VERSION_1:
		err = init_pitch_v1(chip, fmt->endpoint);
		break;
	case UAC_VERSION_2:
		err = init_pitch_v2(chip, fmt->endpoint);
		break;
	default:
		return 0;
	}

	if (err < 0) {
		usb_audio_err(chip, "failed to enable PITCH for EP 0x%x\n",
			      fmt->endpoint);
		return err;
	}

	return 0;
}

static bool stop_endpoints(struct snd_usb_substream *subs)
{
	bool stopped = 0;

	if (test_and_clear_bit(SUBSTREAM_FLAG_SYNC_EP_STARTED, &subs->flags)) {
		snd_usb_endpoint_stop(subs->sync_endpoint);
		stopped = true;
	}
	if (test_and_clear_bit(SUBSTREAM_FLAG_DATA_EP_STARTED, &subs->flags)) {
		snd_usb_endpoint_stop(subs->data_endpoint);
		stopped = true;
	}
	return stopped;
}

static int start_endpoints(struct snd_usb_substream *subs)
{
	int err;

	if (!subs->data_endpoint)
		return -EINVAL;

	if (!test_and_set_bit(SUBSTREAM_FLAG_DATA_EP_STARTED, &subs->flags)) {
		err = snd_usb_endpoint_start(subs->data_endpoint);
		if (err < 0) {
			clear_bit(SUBSTREAM_FLAG_DATA_EP_STARTED, &subs->flags);
			goto error;
		}
	}

	if (subs->sync_endpoint &&
	    !test_and_set_bit(SUBSTREAM_FLAG_SYNC_EP_STARTED, &subs->flags)) {
		err = snd_usb_endpoint_start(subs->sync_endpoint);
		if (err < 0) {
			clear_bit(SUBSTREAM_FLAG_SYNC_EP_STARTED, &subs->flags);
			goto error;
		}
	}

	return 0;

 error:
	stop_endpoints(subs);
	return err;
}

static void sync_pending_stops(struct snd_usb_substream *subs)
{
	snd_usb_endpoint_sync_pending_stop(subs->sync_endpoint);
	snd_usb_endpoint_sync_pending_stop(subs->data_endpoint);
}

/* PCM sync_stop callback */
static int snd_usb_pcm_sync_stop(struct snd_pcm_substream *substream)
{
	struct snd_usb_substream *subs = substream->runtime->private_data;

	if (!snd_usb_lock_shutdown(subs->stream->chip)) {
		sync_pending_stops(subs);
		snd_usb_unlock_shutdown(subs->stream->chip);
	}
	return 0;
}

/* Set up sync endpoint */
int snd_usb_audioformat_set_sync_ep(struct snd_usb_audio *chip,
				    struct audioformat *fmt)
{
	struct usb_device *dev = chip->dev;
	struct usb_host_interface *alts;
	struct usb_interface_descriptor *altsd;
	unsigned int ep, attr, sync_attr;
	bool is_playback;
	int err;

	alts = snd_usb_get_host_interface(chip, fmt->iface, fmt->altsetting);
	if (!alts)
		return 0;
	altsd = get_iface_desc(alts);

	err = snd_usb_parse_implicit_fb_quirk(chip, fmt, alts);
	if (err > 0)
		return 0; /* matched */

	/*
	 * Generic sync EP handling
	 */