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Commit e83bff72 authored by Ajay Agarwal's avatar Ajay Agarwal
Browse files

usb: gadget: split out audio core 



Abstract the peripheral side ALSA sound card code into a
component that can be called by various functions, so the
various flavors can be split apart and selectively reused.

Visible changes:
 - add uac_params structure to pass audio paramteres for
   g_audio_setup
 - make ALSA sound card's name configurable
 - add [in/out]_ep_maxpsize
 - allocate snd_uac_chip structure during g_audio_setup
 - add u_audio_[start/stop]_[capture/playback] functions

This change differs from opensource patch in that it does not
modify the UAC2 driver to use u_audio helper file for ALSA
sound card support.

Change-Id: Ia67ec02ed442a67bc359efc2655aa9ba49b79368
Signed-off-by: default avatarRuslan Bilovol <ruslan.bilovol@gmail.com>
Signed-off-by: default avatarFelipe Balbi <felipe.balbi@linux.intel.com>
Git-commit: eb9fecb9e69b0be8c267c55b0bb52a08e8fb6bee
Git-repo: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git


Signed-off-by: default avatarAjay Agarwal <ajaya@codeaurora.org>
parent a1f2b053

drivers/usb/gadget/Kconfig

+3 −0
Original line number Diff line number Diff line
@@ -151,6 +151,9 @@ config USB_U_SERIAL 
config USB_U_ETHER

	tristate



config USB_U_AUDIO

	tristate



config USB_F_SERIAL

	tristate

drivers/usb/gadget/function/Makefile

+1 −0
Original line number Diff line number Diff line
@@ -32,6 +32,7 @@ usb_f_mass_storage-y := f_mass_storage.o storage_common.o 
obj-$(CONFIG_USB_F_MASS_STORAGE)+= usb_f_mass_storage.o

usb_f_fs-y			:= f_fs.o

obj-$(CONFIG_USB_F_FS)		+= usb_f_fs.o

obj-$(CONFIG_USB_U_AUDIO)	+= u_audio.o

usb_f_uac1-y			:= f_uac1.o u_uac1.o

obj-$(CONFIG_USB_F_UAC1)	+= usb_f_uac1.o

usb_f_uac2-y			:= f_uac2.o

drivers/usb/gadget/function/u_audio.c

0 → 100644
+662 −0
Original line number Diff line number Diff line 
/*

 * u_audio.c -- interface to USB gadget "ALSA sound card" utilities

 *

 * Copyright (C) 2016

 * Author: Ruslan Bilovol <ruslan.bilovol@gmail.com>

 *

 * Sound card implementation was cut-and-pasted with changes

 * from f_uac2.c and has:

 *    Copyright (C) 2011

 *    Yadwinder Singh (yadi.brar01@gmail.com)

 *    Jaswinder Singh (jaswinder.singh@linaro.org)

 *

 * This program is free software; you can redistribute it and/or modify

 * it under the terms of the GNU General Public License as published by

 * the Free Software Foundation; either version 2 of the License, or

 * (at your option) any later version.

 *

 * This program is distributed in the hope that it will be useful,

 * but WITHOUT ANY WARRANTY; without even the implied warranty of

 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

 * GNU General Public License for more details.

 */



#include <linux/module.h>

#include <sound/core.h>

#include <sound/pcm.h>

#include <sound/pcm_params.h>



#include "u_audio.h"



#define BUFF_SIZE_MAX	(PAGE_SIZE * 16)

#define PRD_SIZE_MAX	PAGE_SIZE

#define MIN_PERIODS	4



struct uac_req {

	struct uac_rtd_params *pp; /* parent param */

	struct usb_request *req;

};



/* Runtime data params for one stream */

struct uac_rtd_params {

	struct snd_uac_chip *uac; /* parent chip */

	bool ep_enabled; /* if the ep is enabled */

	/* Size of the ring buffer */

	size_t dma_bytes;

	unsigned char *dma_area;



	struct snd_pcm_substream *ss;



	/* Ring buffer */

	ssize_t hw_ptr;



	void *rbuf;



	size_t period_size;



	unsigned max_psize;	/* MaxPacketSize of endpoint */

	struct uac_req *ureq;



	spinlock_t lock;

};



struct snd_uac_chip {

	struct g_audio *audio_dev;



	struct uac_rtd_params p_prm;

	struct uac_rtd_params c_prm;



	struct snd_card *card;

	struct snd_pcm *pcm;



	/* timekeeping for the playback endpoint */

	unsigned int p_interval;

	unsigned int p_residue;



	/* pre-calculated values for playback iso completion */

	unsigned int p_pktsize;

	unsigned int p_pktsize_residue;

	unsigned int p_framesize;

};



static struct snd_pcm_hardware uac_pcm_hardware = {

	.info = SNDRV_PCM_INFO_INTERLEAVED | SNDRV_PCM_INFO_BLOCK_TRANSFER

		 | SNDRV_PCM_INFO_MMAP | SNDRV_PCM_INFO_MMAP_VALID

		 | SNDRV_PCM_INFO_PAUSE | SNDRV_PCM_INFO_RESUME,

	.rates = SNDRV_PCM_RATE_CONTINUOUS,

	.periods_max = BUFF_SIZE_MAX / PRD_SIZE_MAX,

	.buffer_bytes_max = BUFF_SIZE_MAX,

	.period_bytes_max = PRD_SIZE_MAX,

	.periods_min = MIN_PERIODS,

};



static void u_audio_iso_complete(struct usb_ep *ep, struct usb_request *req)

{

	unsigned pending;

	unsigned long flags;

	unsigned int hw_ptr;

	bool update_alsa = false;

	int status = req->status;

	struct uac_req *ur = req->context;

	struct snd_pcm_substream *substream;

	struct uac_rtd_params *prm = ur->pp;

	struct snd_uac_chip *uac = prm->uac;



	/* i/f shutting down */

	if (!prm->ep_enabled || req->status == -ESHUTDOWN)

		return;



	/*

	 * We can't really do much about bad xfers.

	 * Afterall, the ISOCH xfers could fail legitimately.

	 */

	if (status)

		pr_debug("%s: iso_complete status(%d) %d/%d\n",

			__func__, status, req->actual, req->length);



	substream = prm->ss;



	/* Do nothing if ALSA isn't active */

	if (!substream)

		goto exit;



	spin_lock_irqsave(&prm->lock, flags);



	if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK) {

		/*

		 * For each IN packet, take the quotient of the current data

		 * rate and the endpoint's interval as the base packet size.

		 * If there is a residue from this division, add it to the

		 * residue accumulator.

		 */

		req->length = uac->p_pktsize;

		uac->p_residue += uac->p_pktsize_residue;



		/*

		 * Whenever there are more bytes in the accumulator than we

		 * need to add one more sample frame, increase this packet's

		 * size and decrease the accumulator.

		 */

		if (uac->p_residue / uac->p_interval >= uac->p_framesize) {

			req->length += uac->p_framesize;

			uac->p_residue -= uac->p_framesize *

					   uac->p_interval;

		}



		req->actual = req->length;

	}



	pending = prm->hw_ptr % prm->period_size;

	pending += req->actual;

	if (pending >= prm->period_size)

		update_alsa = true;



	hw_ptr = prm->hw_ptr;

	prm->hw_ptr = (prm->hw_ptr + req->actual) % prm->dma_bytes;



	spin_unlock_irqrestore(&prm->lock, flags);



	/* Pack USB load in ALSA ring buffer */

	pending = prm->dma_bytes - hw_ptr;



	if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK) {

		if (unlikely(pending < req->actual)) {

			memcpy(req->buf, prm->dma_area + hw_ptr, pending);

			memcpy(req->buf + pending, prm->dma_area,

			       req->actual - pending);

		} else {

			memcpy(req->buf, prm->dma_area + hw_ptr, req->actual);

		}

	} else {

		if (unlikely(pending < req->actual)) {

			memcpy(prm->dma_area + hw_ptr, req->buf, pending);

			memcpy(prm->dma_area, req->buf + pending,

			       req->actual - pending);

		} else {

			memcpy(prm->dma_area + hw_ptr, req->buf, req->actual);

		}

	}



exit:

	if (usb_ep_queue(ep, req, GFP_ATOMIC))

		dev_err(uac->card->dev, "%d Error!\n", __LINE__);



	if (update_alsa)

		snd_pcm_period_elapsed(substream);

}



static int uac_pcm_trigger(struct snd_pcm_substream *substream, int cmd)

{

	struct snd_uac_chip *uac = snd_pcm_substream_chip(substream);

	struct uac_rtd_params *prm;

	struct g_audio *audio_dev;

	struct uac_params *params;

	unsigned long flags;

	int err = 0;



	audio_dev = uac->audio_dev;

	params = &audio_dev->params;



	if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK)

		prm = &uac->p_prm;

	else

		prm = &uac->c_prm;



	spin_lock_irqsave(&prm->lock, flags);



	/* Reset */

	prm->hw_ptr = 0;



	switch (cmd) {

	case SNDRV_PCM_TRIGGER_START:

	case SNDRV_PCM_TRIGGER_RESUME:

		prm->ss = substream;

		break;

	case SNDRV_PCM_TRIGGER_STOP:

	case SNDRV_PCM_TRIGGER_SUSPEND:

		prm->ss = NULL;

		break;

	default:

		err = -EINVAL;

	}



	spin_unlock_irqrestore(&prm->lock, flags);



	/* Clear buffer after Play stops */

	if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK && !prm->ss)

		memset(prm->rbuf, 0, prm->max_psize * params->req_number);



	return err;

}



static snd_pcm_uframes_t uac_pcm_pointer(struct snd_pcm_substream *substream)

{

	struct snd_uac_chip *uac = snd_pcm_substream_chip(substream);

	struct uac_rtd_params *prm;



	if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK)

		prm = &uac->p_prm;

	else

		prm = &uac->c_prm;



	return bytes_to_frames(substream->runtime, prm->hw_ptr);

}



static int uac_pcm_hw_params(struct snd_pcm_substream *substream,

			       struct snd_pcm_hw_params *hw_params)

{

	struct snd_uac_chip *uac = snd_pcm_substream_chip(substream);

	struct uac_rtd_params *prm;

	int err;



	if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK)

		prm = &uac->p_prm;

	else

		prm = &uac->c_prm;



	err = snd_pcm_lib_malloc_pages(substream,

					params_buffer_bytes(hw_params));

	if (err >= 0) {

		prm->dma_bytes = substream->runtime->dma_bytes;

		prm->dma_area = substream->runtime->dma_area;

		prm->period_size = params_period_bytes(hw_params);

	}



	return err;

}



static int uac_pcm_hw_free(struct snd_pcm_substream *substream)

{

	struct snd_uac_chip *uac = snd_pcm_substream_chip(substream);

	struct uac_rtd_params *prm;



	if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK)

		prm = &uac->p_prm;

	else

		prm = &uac->c_prm;



	prm->dma_area = NULL;

	prm->dma_bytes = 0;

	prm->period_size = 0;



	return snd_pcm_lib_free_pages(substream);

}



static int uac_pcm_open(struct snd_pcm_substream *substream)

{

	struct snd_uac_chip *uac = snd_pcm_substream_chip(substream);

	struct snd_pcm_runtime *runtime = substream->runtime;

	struct g_audio *audio_dev;

	struct uac_params *params;

	int p_ssize, c_ssize;

	int p_srate, c_srate;

	int p_chmask, c_chmask;



	audio_dev = uac->audio_dev;

	params = &audio_dev->params;

	p_ssize = params->p_ssize;

	c_ssize = params->c_ssize;

	p_srate = params->p_srate;

	c_srate = params->c_srate;

	p_chmask = params->p_chmask;

	c_chmask = params->c_chmask;

	uac->p_residue = 0;



	runtime->hw = uac_pcm_hardware;



	if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK) {

		spin_lock_init(&uac->p_prm.lock);

		runtime->hw.rate_min = p_srate;

		switch (p_ssize) {

		case 3:

			runtime->hw.formats = SNDRV_PCM_FMTBIT_S24_3LE;

			break;

		case 4:

			runtime->hw.formats = SNDRV_PCM_FMTBIT_S32_LE;

			break;

		default:

			runtime->hw.formats = SNDRV_PCM_FMTBIT_S16_LE;

			break;

		}

		runtime->hw.channels_min = num_channels(p_chmask);

		runtime->hw.period_bytes_min = 2 * uac->p_prm.max_psize

						/ runtime->hw.periods_min;

	} else {

		spin_lock_init(&uac->c_prm.lock);

		runtime->hw.rate_min = c_srate;

		switch (c_ssize) {

		case 3:

			runtime->hw.formats = SNDRV_PCM_FMTBIT_S24_3LE;

			break;

		case 4:

			runtime->hw.formats = SNDRV_PCM_FMTBIT_S32_LE;

			break;

		default:

			runtime->hw.formats = SNDRV_PCM_FMTBIT_S16_LE;

			break;

		}

		runtime->hw.channels_min = num_channels(c_chmask);

		runtime->hw.period_bytes_min = 2 * uac->c_prm.max_psize

						/ runtime->hw.periods_min;

	}



	runtime->hw.rate_max = runtime->hw.rate_min;

	runtime->hw.channels_max = runtime->hw.channels_min;



	snd_pcm_hw_constraint_integer(runtime, SNDRV_PCM_HW_PARAM_PERIODS);



	return 0;

}



/* ALSA cries without these function pointers */

static int uac_pcm_null(struct snd_pcm_substream *substream)

{

	return 0;

}



static struct snd_pcm_ops uac_pcm_ops = {

	.open = uac_pcm_open,

	.close = uac_pcm_null,

	.ioctl = snd_pcm_lib_ioctl,

	.hw_params = uac_pcm_hw_params,

	.hw_free = uac_pcm_hw_free,

	.trigger = uac_pcm_trigger,

	.pointer = uac_pcm_pointer,

	.prepare = uac_pcm_null,

};



static inline void free_ep(struct uac_rtd_params *prm, struct usb_ep *ep)

{

	struct snd_uac_chip *uac = prm->uac;

	struct g_audio *audio_dev;

	struct uac_params *params;

	int i;



	if (!prm->ep_enabled)

		return;



	prm->ep_enabled = false;



	audio_dev = uac->audio_dev;

	params = &audio_dev->params;



	for (i = 0; i < params->req_number; i++) {

		if (prm->ureq[i].req) {

			usb_ep_dequeue(ep, prm->ureq[i].req);

			usb_ep_free_request(ep, prm->ureq[i].req);

			prm->ureq[i].req = NULL;

		}

	}



	if (usb_ep_disable(ep))

		dev_err(uac->card->dev, "%s:%d Error!\n", __func__, __LINE__);

}





int u_audio_start_capture(struct g_audio *audio_dev)

{

	struct snd_uac_chip *uac = audio_dev->uac;

	struct usb_gadget *gadget = audio_dev->gadget;

	struct device *dev = &gadget->dev;

	struct usb_request *req;

	struct usb_ep *ep;

	struct uac_rtd_params *prm;

	struct uac_params *params = &audio_dev->params;

	int req_len, i;



	ep = audio_dev->out_ep;

	prm = &uac->c_prm;

	config_ep_by_speed(gadget, &audio_dev->func, ep);

	req_len = prm->max_psize;



	prm->ep_enabled = true;

	usb_ep_enable(ep);



	for (i = 0; i < params->req_number; i++) {

		if (!prm->ureq[i].req) {

			req = usb_ep_alloc_request(ep, GFP_ATOMIC);

			if (req == NULL)

				return -ENOMEM;



			prm->ureq[i].req = req;

			prm->ureq[i].pp = prm;



			req->zero = 0;

			req->context = &prm->ureq[i];

			req->length = req_len;

			req->complete = u_audio_iso_complete;

			req->buf = prm->rbuf + i * prm->max_psize;

		}



		if (usb_ep_queue(ep, prm->ureq[i].req, GFP_ATOMIC))

			dev_err(dev, "%s:%d Error!\n", __func__, __LINE__);

	}



	return 0;

}

EXPORT_SYMBOL_GPL(u_audio_start_capture);



void u_audio_stop_capture(struct g_audio *audio_dev)

{

	struct snd_uac_chip *uac = audio_dev->uac;



	free_ep(&uac->c_prm, audio_dev->out_ep);

}

EXPORT_SYMBOL_GPL(u_audio_stop_capture);



int u_audio_start_playback(struct g_audio *audio_dev)

{

	struct snd_uac_chip *uac = audio_dev->uac;

	struct usb_gadget *gadget = audio_dev->gadget;

	struct device *dev = &gadget->dev;

	struct usb_request *req;

	struct usb_ep *ep;

	struct uac_rtd_params *prm;

	struct uac_params *params = &audio_dev->params;

	unsigned int factor, rate;

	const struct usb_endpoint_descriptor *ep_desc;

	int req_len, i;



	ep = audio_dev->in_ep;

	prm = &uac->p_prm;

	config_ep_by_speed(gadget, &audio_dev->func, ep);



	ep_desc = ep->desc;



	/* pre-calculate the playback endpoint's interval */

	if (gadget->speed == USB_SPEED_FULL)

		factor = 1000;

	else

		factor = 8000;



	/* pre-compute some values for iso_complete() */

	uac->p_framesize = params->p_ssize *

			    num_channels(params->p_chmask);

	rate = params->p_srate * uac->p_framesize;

	uac->p_interval = factor / (1 << (ep_desc->bInterval - 1));

	uac->p_pktsize = min_t(unsigned int, rate / uac->p_interval,

				prm->max_psize);



	if (uac->p_pktsize < prm->max_psize)

		uac->p_pktsize_residue = rate % uac->p_interval;

	else

		uac->p_pktsize_residue = 0;



	req_len = uac->p_pktsize;

	uac->p_residue = 0;



	prm->ep_enabled = true;

	usb_ep_enable(ep);



	for (i = 0; i < params->req_number; i++) {

		if (!prm->ureq[i].req) {

			req = usb_ep_alloc_request(ep, GFP_ATOMIC);

			if (req == NULL)

				return -ENOMEM;



			prm->ureq[i].req = req;

			prm->ureq[i].pp = prm;



			req->zero = 0;

			req->context = &prm->ureq[i];

			req->length = req_len;

			req->complete = u_audio_iso_complete;

			req->buf = prm->rbuf + i * prm->max_psize;

		}



		if (usb_ep_queue(ep, prm->ureq[i].req, GFP_ATOMIC))

			dev_err(dev, "%s:%d Error!\n", __func__, __LINE__);

	}



	return 0;

}

EXPORT_SYMBOL_GPL(u_audio_start_playback);



void u_audio_stop_playback(struct g_audio *audio_dev)

{

	struct snd_uac_chip *uac = audio_dev->uac;



	free_ep(&uac->p_prm, audio_dev->in_ep);

}

EXPORT_SYMBOL_GPL(u_audio_stop_playback);



int g_audio_setup(struct g_audio *g_audio, const char *pcm_name,

					const char *card_name)

{

	struct snd_uac_chip *uac;

	struct snd_card *card;

	struct snd_pcm *pcm;

	struct uac_params *params;

	int p_chmask, c_chmask;

	int err;



	if (!g_audio)

		return -EINVAL;



	uac = kzalloc(sizeof(*uac), GFP_KERNEL);

	if (!uac)

		return -ENOMEM;

	g_audio->uac = uac;

	uac->audio_dev = g_audio;



	params = &g_audio->params;

	p_chmask = params->p_chmask;

	c_chmask = params->c_chmask;



	if (c_chmask) {

		struct uac_rtd_params *prm = &uac->c_prm;



		uac->c_prm.uac = uac;

		prm->max_psize = g_audio->out_ep_maxpsize;



		prm->ureq = kcalloc(params->req_number, sizeof(struct uac_req),

				GFP_KERNEL);

		if (!prm->ureq) {

			err = -ENOMEM;

			goto fail;

		}



		prm->rbuf = kcalloc(params->req_number, prm->max_psize,

				GFP_KERNEL);

		if (!prm->rbuf) {

			prm->max_psize = 0;

			err = -ENOMEM;

			goto fail;

		}

	}



	if (p_chmask) {

		struct uac_rtd_params *prm = &uac->p_prm;



		uac->p_prm.uac = uac;

		prm->max_psize = g_audio->in_ep_maxpsize;



		prm->ureq = kcalloc(params->req_number, sizeof(struct uac_req),

				GFP_KERNEL);

		if (!prm->ureq) {

			err = -ENOMEM;

			goto fail;

		}



		prm->rbuf = kcalloc(params->req_number, prm->max_psize,

				GFP_KERNEL);

		if (!prm->rbuf) {

			prm->max_psize = 0;

			err = -ENOMEM;

			goto fail;

		}

	}



	/* Choose any slot, with no id */

	err = snd_card_new(&g_audio->gadget->dev,

			-1, NULL, THIS_MODULE, 0, &card);

	if (err < 0)

		goto fail;



	uac->card = card;



	/*

	 * Create first PCM device

	 * Create a substream only for non-zero channel streams

	 */

	err = snd_pcm_new(uac->card, pcm_name, 0,

			       p_chmask ? 1 : 0, c_chmask ? 1 : 0, &pcm);

	if (err < 0)

		goto snd_fail;



	strcpy(pcm->name, pcm_name);

	pcm->private_data = uac;

	uac->pcm = pcm;



	snd_pcm_set_ops(pcm, SNDRV_PCM_STREAM_PLAYBACK, &uac_pcm_ops);

	snd_pcm_set_ops(pcm, SNDRV_PCM_STREAM_CAPTURE, &uac_pcm_ops);



	strcpy(card->driver, card_name);

	strcpy(card->shortname, card_name);

	sprintf(card->longname, "%s %i", card_name, card->dev->id);



	snd_pcm_lib_preallocate_pages_for_all(pcm, SNDRV_DMA_TYPE_CONTINUOUS,

		snd_dma_continuous_data(GFP_KERNEL), 0, BUFF_SIZE_MAX);



	err = snd_card_register(card);



	if (!err)

		return 0;



snd_fail:

	snd_card_free(card);

fail:

	kfree(uac->p_prm.ureq);

	kfree(uac->c_prm.ureq);

	kfree(uac->p_prm.rbuf);

	kfree(uac->c_prm.rbuf);

	kfree(uac);



	return err;

}

EXPORT_SYMBOL_GPL(g_audio_setup);



void g_audio_cleanup(struct g_audio *g_audio)

{

	struct snd_uac_chip *uac;

	struct snd_card *card;



	if (!g_audio || !g_audio->uac)

		return;



	uac = g_audio->uac;

	card = uac->card;

	if (card)

		snd_card_free(card);



	kfree(uac->p_prm.ureq);

	kfree(uac->c_prm.ureq);

	kfree(uac->p_prm.rbuf);

	kfree(uac->c_prm.rbuf);

	kfree(uac);

}

EXPORT_SYMBOL_GPL(g_audio_cleanup);



MODULE_LICENSE("GPL");

MODULE_DESCRIPTION("USB gadget \"ALSA sound card\" utilities");

MODULE_AUTHOR("Ruslan Bilovol");

drivers/usb/gadget/function/u_audio.h

0 → 100644
+95 −0
Original line number Diff line number Diff line 
/*

 * u_audio.h -- interface to USB gadget "ALSA sound card" utilities

 *

 * Copyright (C) 2016

 * Author: Ruslan Bilovol <ruslan.bilovol@gmail.com>

 *

 * This program is free software; you can redistribute it and/or modify

 * it under the terms of the GNU General Public License as published by

 * the Free Software Foundation; either version 2 of the License, or

 * (at your option) any later version.

 *

 * This program is distributed in the hope that it will be useful,

 * but WITHOUT ANY WARRANTY; without even the implied warranty of

 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

 * GNU General Public License for more details.

 *

 */



#ifndef __U_AUDIO_H

#define __U_AUDIO_H



#include <linux/usb/composite.h>



struct uac_params {

	/* playback */

	int p_chmask;	/* channel mask */

	int p_srate;	/* rate in Hz */

	int p_ssize;	/* sample size */



	/* capture */

	int c_chmask;	/* channel mask */

	int c_srate;	/* rate in Hz */

	int c_ssize;	/* sample size */



	int req_number; /* number of preallocated requests */

};



struct g_audio {

	struct usb_function func;

	struct usb_gadget *gadget;



	struct usb_ep *in_ep;

	struct usb_ep *out_ep;



	/* Max packet size for all in_ep possible speeds */

	unsigned int in_ep_maxpsize;

	/* Max packet size for all out_ep possible speeds */

	unsigned int out_ep_maxpsize;



	/* The ALSA Sound Card it represents on the USB-Client side */

	struct snd_uac_chip *uac;



	struct uac_params params;

};



static inline struct g_audio *func_to_g_audio(struct usb_function *f)

{

	return container_of(f, struct g_audio, func);

}



static inline uint num_channels(uint chanmask)

{

	uint num = 0;



	while (chanmask) {

		num += (chanmask & 1);

		chanmask >>= 1;

	}



	return num;

}



/*

 * g_audio_setup - initialize one virtual ALSA sound card

 * @g_audio: struct with filled params, in_ep_maxpsize, out_ep_maxpsize

 * @pcm_name: the id string for a PCM instance of this sound card

 * @card_name: name of this soundcard

 *

 * This sets up the single virtual ALSA sound card that may be exported by a

 * gadget driver using this framework.

 *

 * Context: may sleep

 *

 * Returns zero on success, or a negative error on failure.

 */

int g_audio_setup(struct g_audio *g_audio, const char *pcm_name,

					const char *card_name);

void g_audio_cleanup(struct g_audio *g_audio);



int u_audio_start_capture(struct g_audio *g_audio);

void u_audio_stop_capture(struct g_audio *g_audio);

int u_audio_start_playback(struct g_audio *g_audio);

void u_audio_stop_playback(struct g_audio *g_audio);



#endif /* __U_AUDIO_H */