path: root/sound/usb/endpoint.c

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

#include <linux/gfp.h>
#include <linux/init.h>
#include <linux/ratelimit.h>
#include <linux/usb.h>
#include <linux/usb/audio.h>
#include <linux/slab.h>

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

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

#define EP_FLAG_RUNNING		1
#define EP_FLAG_STOPPING	2

/*
 * snd_usb_endpoint is a model that abstracts everything related to an
 * USB endpoint and its streaming.
 *
 * There are functions to activate and deactivate the streaming URBs and
 * optional callbacks to let the pcm logic handle the actual content of the
 * packets for playback and record. Thus, the bus streaming and the audio
 * handlers are fully decoupled.
 *
 * There are two different types of endpoints in audio applications.
 *
 * SND_USB_ENDPOINT_TYPE_DATA handles full audio data payload for both
 * inbound and outbound traffic.
 *
 * SND_USB_ENDPOINT_TYPE_SYNC endpoints are for inbound traffic only and
 * expect the payload to carry Q10.14 / Q16.16 formatted sync information
 * (3 or 4 bytes).
 *
 * Each endpoint has to be configured prior to being used by calling
 * snd_usb_endpoint_set_params().
 *
 * The model incorporates a reference counting, so that multiple users
 * can call snd_usb_endpoint_start() and snd_usb_endpoint_stop(), and
 * only the first user will effectively start the URBs, and only the last
 * one to stop it will tear the URBs down again.
 */

/*
 * convert a sampling rate into our full speed format (fs/1000 in Q16.16)
 * this will overflow at approx 524 kHz
 */
static inline unsigned get_usb_full_speed_rate(unsigned int rate)
{
	return ((rate << 13) + 62) / 125;
}

/*
 * convert a sampling rate into USB high speed format (fs/8000 in Q16.16)
 * this will overflow at approx 4 MHz
 */
static inline unsigned get_usb_high_speed_rate(unsigned int rate)
{
	return ((rate << 10) + 62) / 125;
}

/*
 * release a urb data
 */
static void release_urb_ctx(struct snd_urb_ctx *u)
{
	if (u->buffer_size)
		usb_free_coherent(u->ep->chip->dev, u->buffer_size,
				  u->urb->transfer_buffer,
				  u->urb->transfer_dma);
	usb_free_urb(u->urb);
	u->urb = NULL;
}

static const char *usb_error_string(int err)
{
	switch (err) {
	case -ENODEV:
		return "no device";
	case -ENOENT:
		return "endpoint not enabled";
	case -EPIPE:
		return "endpoint stalled";
	case -ENOSPC:
		return "not enough bandwidth";
	case -ESHUTDOWN:
		return "device disabled";
	case -EHOSTUNREACH:
		return "device suspended";
	case -EINVAL:
	case -EAGAIN:
	case -EFBIG:
	case -EMSGSIZE:
		return "internal error";
	default:
		return "unknown error";
	}
}

/**
 * snd_usb_endpoint_implicit_feedback_sink: Report endpoint usage type
 *
 * @ep: The snd_usb_endpoint
 *
 * Determine whether an endpoint is driven by an implicit feedback
 * data endpoint source.
 */
int snd_usb_endpoint_implicit_feedback_sink(struct snd_usb_endpoint *ep)
{
	return  ep->implicit_fb_sync && usb_pipeout(ep->pipe);
}

/*
 * Return the number of samples to be sent in the next packet
 * for streaming based on information derived from sync endpoints
 *
 * This won't be used for implicit feedback which takes the packet size
 * returned from the sync source
 */
static int slave_next_packet_size(struct snd_usb_endpoint *ep)
{
	unsigned long flags;
	int ret;

	if (ep->fill_max)
		return ep->maxframesize;

	spin_lock_irqsave(&ep->lock, flags);
	ep->phase = (ep->phase & 0xffff)
		+ (ep->freqm << ep->datainterval);
	ret = min(ep->phase >> 16, ep->maxframesize);
	spin_unlock_irqrestore(&ep->lock, flags);

	return ret;
}

/*
 * Return the number of samples to be sent in the next packet
 * for adaptive and synchronous endpoints
 */
static int next_packet_size(struct snd_usb_endpoint *ep)
{
	int ret;

	if (ep->fill_max)
		return ep->maxframesize;

	ep->sample_accum += ep->sample_rem;
	if (ep->sample_accum >= ep->pps) {
		ep->sample_accum -= ep->pps;
		ret = ep->packsize[1];
	} else {
		ret = ep->packsize[0];
	}

	return ret;
}

/*
 * snd_usb_endpoint_next_packet_size: Return the number of samples to be sent
 * in the next packet
 */
int snd_usb_endpoint_next_packet_size(struct snd_usb_endpoint *ep,
				      struct snd_urb_ctx *ctx, int idx)
{
	if (ctx->packet_size[idx])
		return ctx->packet_size[idx];
	else if (ep->sync_source)
		return slave_next_packet_size(ep);
	else
		return next_packet_size(ep);
}

static void call_retire_callback(struct snd_usb_endpoint *ep,
				 struct urb *urb)
{
	struct snd_usb_substream *data_subs;

	data_subs = READ_ONCE(ep->data_subs);
	if (data_subs && ep->retire_data_urb)
		ep->retire_data_urb(data_subs, urb);
}

static void retire_outbound_urb(struct snd_usb_endpoint *ep,
				struct snd_urb_ctx *urb_ctx)
{
	call_retire_callback(ep, urb_ctx->urb);
}

static void snd_usb_handle_sync_urb(struct snd_usb_endpoint *ep,
				    struct snd_usb_endpoint *sender,
				    const struct urb *urb);

static void retire_inbound_urb(struct snd_usb_endpoint *ep,
			       struct snd_urb_ctx *urb_ctx)
{
	struct urb *urb = urb_ctx->urb;
	struct snd_usb_endpoint *sync_sink;

	if (unlikely(ep->skip_packets > 0)) {
		ep->skip_packets--;
		return;
	}

	sync_sink = READ_ONCE(ep->sync_sink);
	if (sync_sink)
		snd_usb_handle_sync_urb(sync_sink, ep, urb);

	call_retire_callback(ep, urb);
}

static void prepare_silent_urb(struct snd_usb_endpoint *ep,
			       struct snd_urb_ctx *ctx)
{
	struct urb *urb = ctx->urb;
	unsigned int offs = 0;
	unsigned int extra = 0;
	__le32 packet_length;
	int i;

	/* For tx_length_quirk, put packet length at start of packet */
	if (ep->chip->tx_length_quirk)
		extra = sizeof(packet_length);

	for (i = 0; i < ctx->packets; ++i) {
		unsigned int offset;
		unsigned int length;
		int counts;

		counts = snd_usb_endpoint_next_packet_size(ep, ctx, i);
		length = counts * ep->stride; /* number of silent bytes */
		offset = offs * ep->stride + extra * i;
		urb->iso_frame_desc[i].offset = offset;
		urb->iso_frame_desc[i].length = length + extra;
		if (extra) {
			packet_length = cpu_to_le32(length);
			memcpy(urb->transfer_buffer + offset,
			       &packet_le