[libsigrok.git] / hardware / alsa / alsa.c

/*
 * This file is part of the sigrok project.
 *
 * Copyright (C) 2011 Daniel Ribeiro <drwyrm@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.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301 USA
 */

#include "config.h" /* Must come before sigrok.h */
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <alsa/asoundlib.h>
#include "sigrok.h"
#include "sigrok-internal.h"

#define NUM_PROBES 2
#define SAMPLE_WIDTH 16
#define AUDIO_DEV "plughw:0,0"

static int capabilities[] = {
	SR_HWCAP_SAMPLERATE,
	SR_HWCAP_LIMIT_SAMPLES,
	SR_HWCAP_CONTINUOUS,
};

static const char *probe_names[NUM_PROBES + 1] = {
	"0",
	"1",
	NULL,
};

static GSList *device_instances = NULL;

struct alsa {
	uint64_t cur_rate;
	uint64_t limit_samples;
	snd_pcm_t *capture_handle;
	snd_pcm_hw_params_t *hw_params;
	gpointer session_id;
};

static int hw_init(const char *deviceinfo)
{
	struct sr_device_instance *sdi;
	struct alsa *alsa;

	/* Avoid compiler warnings. */
	deviceinfo = deviceinfo;

	if (!(alsa = g_try_malloc0(sizeof(struct alsa)))) {
		sr_err("alsa: %s: alsa malloc failed", __func__);
		return 0;
	}

	sdi = sr_device_instance_new(0, SR_ST_ACTIVE, "alsa", NULL, NULL);
	if (!sdi)
		goto free_alsa;

	sdi->priv = alsa;

	device_instances = g_slist_append(device_instances, sdi);

	return 1;
free_alsa:
	g_free(alsa);
	return 0;
}

static int hw_opendev(int device_index)
{
	struct sr_device_instance *sdi;
	struct alsa *alsa;
	int err;

	if (!(sdi = sr_get_device_instance(device_instances, device_index)))
		return SR_ERR;
	alsa = sdi->priv;

	err = snd_pcm_open(&alsa->capture_handle, AUDIO_DEV,
					SND_PCM_STREAM_CAPTURE, 0);
	if (err < 0) {
		sr_warn("cannot open audio device %s (%s)", AUDIO_DEV,
			snd_strerror(err));
		return SR_ERR;
	}

	err = snd_pcm_hw_params_malloc(&alsa->hw_params);
	if (err < 0) {
		sr_warn("cannot allocate hardware parameter structure (%s)",
			snd_strerror(err));
		return SR_ERR;
	}

	err = snd_pcm_hw_params_any(alsa->capture_handle, alsa->hw_params);
	if (err < 0) {
		sr_warn("cannot initialize hardware parameter structure (%s)",
				snd_strerror(err));
		return SR_ERR;
	}

	return SR_OK;
}

static int hw_closedev(int device_index)
{
	struct sr_device_instance *sdi;
	struct alsa *alsa;

	if (!(sdi = sr_get_device_instance(device_instances, device_index))) {
		sr_err("alsa: %s: sdi was NULL", __func__);
		return SR_ERR; /* TODO: SR_ERR_ARG? */
	}

	if (!(alsa = sdi->priv)) {
		sr_err("alsa: %s: sdi->priv was NULL", __func__);
		return SR_ERR; /* TODO: SR_ERR_ARG? */
	}

	// TODO: Return values of snd_*?
	if (alsa->hw_params)
		snd_pcm_hw_params_free(alsa->hw_params);
	if (alsa->capture_handle)
		snd_pcm_close(alsa->capture_handle);

	return SR_OK;
}

static void hw_cleanup(void)
{
	struct sr_device_instance *sdi;

	if (!(sdi = sr_get_device_instance(device_instances, 0)))
		return;

	free(sdi->priv);
	sr_device_instance_free(sdi);
}

static void *hw_get_device_info(int device_index, int device_info_id)
{
	struct sr_device_instance *sdi;
	struct alsa *alsa;
	void *info = NULL;

	if (!(sdi = sr_get_device_instance(device_instances, device_index)))
		return NULL;
	alsa = sdi->priv;

	switch (device_info_id) {
	case SR_DI_INSTANCE:
		info = sdi;
		break;
	case SR_DI_NUM_PROBES:
		info = GINT_TO_POINTER(NUM_PROBES);
		break;
	case SR_DI_PROBE_NAMES:
		info = probe_names;
		break;
	case SR_DI_CUR_SAMPLERATE:
		info = &alsa->cur_rate;
		break;
	// case SR_DI_PROBE_TYPE:
	// 	info = GINT_TO_POINTER(SR_PROBE_TYPE_ANALOG);
	// 	break;
	}

	return info;
}

static int hw_get_status(int device_index)
{
	/* Avoid compiler warnings. */
	device_index = device_index;

	return SR_ST_ACTIVE;
}

static int *hw_get_capabilities(void)
{
	return capabilities;
}

static int hw_set_configuration(int device_index, int capability, void *value)
{
	struct sr_device_instance *sdi;
	struct alsa *alsa;

	if (!(sdi = sr_get_device_instance(device_instances, device_index)))
		return SR_ERR;
	alsa = sdi->priv;

	switch (capability) {
	case SR_HWCAP_PROBECONFIG:
		return SR_OK;
	case SR_HWCAP_SAMPLERATE:
		alsa->cur_rate = *(uint64_t *) value;
		return SR_OK;
	case SR_HWCAP_LIMIT_SAMPLES:
		alsa->limit_samples = *(uint64_t *) value;
		return SR_OK;
	default:
		return SR_ERR;
	}
}

static int receive_data(int fd, int revents, void *user_data)
{
	struct sr_device_instance *sdi = user_data;
	struct alsa *alsa = sdi->priv;
	struct sr_datafeed_packet packet;
	struct sr_analog_sample *sample;
	unsigned int sample_size = sizeof(struct sr_analog_sample) +
		(NUM_PROBES * sizeof(struct sr_analog_probe));
	char *outb;
	char inb[4096];
	int i, x, count;

	fd = fd;
	revents = revents;

	do {
		memset(inb, 0, sizeof(inb));
		count = snd_pcm_readi(alsa->capture_handle, inb,
			MIN(4096/4, alsa->limit_samples));
		if (count < 1) {
			sr_warn("Failed to read samples");
			return FALSE;
		}

		if (!(outb = g_try_malloc(sample_size * count))) {
			sr_err("alsa: %s: outb malloc failed", __func__);
			return FALSE;
		}

		for (i = 0; i < count; i++) {
			sample = (struct sr_analog_sample *)
						(outb + (i * sample_size));
			sample->num_probes = NUM_PROBES;

			for (x = 0; x < NUM_PROBES; x++) {
				sample->probes[x].val =
					*(uint16_t *) (inb + (i * 4) + (x * 2));
				sample->probes[x].val &= ((1 << 16) - 1);
				sample->probes[x].res = 16;
			}
		}

		packet.type = SR_DF_ANALOG;
		packet.length = count * sample_size;
		packet.unitsize = sample_size;
		packet.payload = outb;
		sr_session_bus(user_data, &packet);
		g_free(outb);
		alsa->limit_samples -= count;

	} while (alsa->limit_samples > 0);

	packet.type = SR_DF_END;
	sr_session_bus(user_data, &packet);

	return TRUE;
}

static int hw_start_acquisition(int device_index, gpointer session_device_id)
{
	struct sr_device_instance *sdi;
	struct alsa *alsa;
	struct sr_datafeed_packet packet;
	struct sr_datafeed_header header;
	struct pollfd *ufds;
	int count;
	int err;

	if (!(sdi = sr_get_device_instance(device_instances, device_index)))
		return SR_ERR;
	alsa = sdi->priv;

	err = snd_pcm_hw_params_set_access(alsa->capture_handle,
			alsa->hw_params, SND_PCM_ACCESS_RW_INTERLEAVED);
	if (err < 0) {
		sr_warn("cannot set access type (%s)", snd_strerror(err));
		return SR_ERR;
	}

	/* FIXME: Hardcoded for 16bits */
	err = snd_pcm_hw_params_set_format(alsa->capture_handle,
			alsa->hw_params, SND_PCM_FORMAT_S16_LE);
	if (err < 0) {
		sr_warn("cannot set sample format (%s)", snd_strerror(err));
		return SR_ERR;
	}

	err = snd_pcm_hw_params_set_rate_near(alsa->capture_handle,
			alsa->hw_params, (unsigned int *) &alsa->cur_rate, 0);
	if (err < 0) {
		sr_warn("cannot set sample rate (%s)", snd_strerror(err));
		return SR_ERR;
	}

	err = snd_pcm_hw_params_set_channels(alsa->capture_handle,
			alsa->hw_params, NUM_PROBES);
	if (err < 0) {
		sr_warn("cannot set channel count (%s)", snd_strerror(err));
		return SR_ERR;
	}

	err = snd_pcm_hw_params(alsa->capture_handle, alsa->hw_params);
	if (err < 0) {
		sr_warn("cannot set parameters (%s)", snd_strerror(err));
		return SR_ERR;
	}

	err = snd_pcm_prepare(alsa->capture_handle);
	if (err < 0) {
		sr_warn("cannot prepare audio interface for use (%s)",
				snd_strerror(err));
		return SR_ERR;
	}

	count = snd_pcm_poll_descriptors_count(alsa->capture_handle);
	if (count < 1) {
		sr_warn("Unable to obtain poll descriptors count");
		return SR_ERR;
	}

	if (!(ufds = g_try_malloc(count * sizeof(struct pollfd)))) {
		sr_warn("alsa: %s: ufds malloc failed", __func__);
		return SR_ERR_MALLOC;
	}

	err = snd_pcm_poll_descriptors(alsa->capture_handle, ufds, count);
	if (err < 0) {
		sr_warn("Unable to obtain poll descriptors (%s)",
				snd_strerror(err));
		g_free(ufds);
		return SR_ERR;
	}

	alsa->session_id = session_device_id;
	sr_source_add(ufds[0].fd, ufds[0].events, 10, receive_data, sdi);

	packet.type = SR_DF_HEADER;
	packet.length = sizeof(struct sr_datafeed_header);
	packet.payload = (unsigned char *) &header;
	header.feed_version = 1;
	gettimeofday(&header.starttime, NULL);
	header.samplerate = alsa->cur_rate;
	header.num_analog_probes = NUM_PROBES;
	header.num_logic_probes = 0;
	header.protocol_id = SR_PROTO_RAW;
	sr_session_bus(session_device_id, &packet);
	g_free(ufds);

	return SR_OK;
}

static void hw_stop_acquisition(int device_index, gpointer session_device_id)
{
	/* Avoid compiler warnings. */
	device_index = device_index;
	session_device_id = session_device_id;
}

struct sr_device_plugin alsa_plugin_info = {
	.name = "alsa",
	.longname = "ALSA driver",
	.api_version = 1,
	.init = hw_init,
	.cleanup = hw_cleanup,
	.opendev = hw_opendev,
	.closedev = hw_closedev,
	.get_device_info = hw_get_device_info,
	.get_status = hw_get_status,
	.get_capabilities = hw_get_capabilities,
	.set_configuration = hw_set_configuration,
	.start_acquisition = hw_start_acquisition,
	.stop_acquisition = hw_stop_acquisition,
};
Commit	Line	Data
	1	/*
	2	* This file is part of the sigrok project.
	3	*
	4	* Copyright (C) 2011 Daniel Ribeiro <drwyrm@gmail.com>
	5	*
	6	* This program is free software; you can redistribute it and/or modify
	7	* it under the terms of the GNU General Public License as published by
	8	* the Free Software Foundation; either version 2 of the License, or
	9	* (at your option) any later version.
	10	*
	11	* This program is distributed in the hope that it will be useful,
	12	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	13	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	14	* GNU General Public License for more details.
	15	*
	16	* You should have received a copy of the GNU General Public License
	17	* along with this program; if not, write to the Free Software
	18	* Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
	19	*/
	20
	21	#include "config.h" /* Must come before sigrok.h */
	22	#include <stdlib.h>
	23	#include <unistd.h>
	24	#include <string.h>
	25	#include <alsa/asoundlib.h>
	26	#include "sigrok.h"
	27	#include "sigrok-internal.h"
	28
	29	#define NUM_PROBES 2
	30	#define SAMPLE_WIDTH 16
	31	#define AUDIO_DEV "plughw:0,0"
	32
	33	static int capabilities[] = {
	34	SR_HWCAP_SAMPLERATE,
	35	SR_HWCAP_LIMIT_SAMPLES,
	36	SR_HWCAP_CONTINUOUS,
	37	};
	38
	39	static const char *probe_names[NUM_PROBES + 1] = {
	40	"0",
	41	"1",
	42	NULL,
	43	};
	44
	45	static GSList *device_instances = NULL;
	46
	47	struct alsa {
	48	uint64_t cur_rate;
	49	uint64_t limit_samples;
	50	snd_pcm_t *capture_handle;
	51	snd_pcm_hw_params_t *hw_params;
	52	gpointer session_id;
	53	};
	54
	55	static int hw_init(const char *deviceinfo)
	56	{
	57	struct sr_device_instance *sdi;
	58	struct alsa *alsa;
	59
	60	/* Avoid compiler warnings. */
	61	deviceinfo = deviceinfo;
	62
	63	if (!(alsa = g_try_malloc0(sizeof(struct alsa)))) {
	64	sr_err("alsa: %s: alsa malloc failed", __func__);
	65	return 0;
	66	}
	67
	68	sdi = sr_device_instance_new(0, SR_ST_ACTIVE, "alsa", NULL, NULL);
	69	if (!sdi)
	70	goto free_alsa;
	71
	72	sdi->priv = alsa;
	73
	74	device_instances = g_slist_append(device_instances, sdi);
	75
	76	return 1;
	77	free_alsa:
	78	g_free(alsa);
	79	return 0;
	80	}
	81
	82	static int hw_opendev(int device_index)
	83	{
	84	struct sr_device_instance *sdi;
	85	struct alsa *alsa;
	86	int err;
	87
	88	if (!(sdi = sr_get_device_instance(device_instances, device_index)))
	89	return SR_ERR;
	90	alsa = sdi->priv;
	91
	92	err = snd_pcm_open(&alsa->capture_handle, AUDIO_DEV,
	93	SND_PCM_STREAM_CAPTURE, 0);
	94	if (err < 0) {
	95	sr_warn("cannot open audio device %s (%s)", AUDIO_DEV,
	96	snd_strerror(err));
	97	return SR_ERR;
	98	}
	99
	100	err = snd_pcm_hw_params_malloc(&alsa->hw_params);
	101	if (err < 0) {
	102	sr_warn("cannot allocate hardware parameter structure (%s)",
	103	snd_strerror(err));
	104	return SR_ERR;
	105	}
	106
	107	err = snd_pcm_hw_params_any(alsa->capture_handle, alsa->hw_params);
	108	if (err < 0) {
	109	sr_warn("cannot initialize hardware parameter structure (%s)",
	110	snd_strerror(err));
	111	return SR_ERR;
	112	}
	113
	114	return SR_OK;
	115	}
	116
	117	static int hw_closedev(int device_index)
	118	{
	119	struct sr_device_instance *sdi;
	120	struct alsa *alsa;
	121
	122	if (!(sdi = sr_get_device_instance(device_instances, device_index))) {
	123	sr_err("alsa: %s: sdi was NULL", __func__);
	124	return SR_ERR; /* TODO: SR_ERR_ARG? */
	125	}
	126
	127	if (!(alsa = sdi->priv)) {
	128	sr_err("alsa: %s: sdi->priv was NULL", __func__);
	129	return SR_ERR; /* TODO: SR_ERR_ARG? */
	130	}
	131
	132	// TODO: Return values of snd_*?
	133	if (alsa->hw_params)
	134	snd_pcm_hw_params_free(alsa->hw_params);
	135	if (alsa->capture_handle)
	136	snd_pcm_close(alsa->capture_handle);
	137
	138	return SR_OK;
	139	}
	140
	141	static void hw_cleanup(void)
	142	{
	143	struct sr_device_instance *sdi;
	144
	145	if (!(sdi = sr_get_device_instance(device_instances, 0)))
	146	return;
	147
	148	free(sdi->priv);
	149	sr_device_instance_free(sdi);
	150	}
	151
	152	static void *hw_get_device_info(int device_index, int device_info_id)
	153	{
	154	struct sr_device_instance *sdi;
	155	struct alsa *alsa;
	156	void *info = NULL;
	157
	158	if (!(sdi = sr_get_device_instance(device_instances, device_index)))
	159	return NULL;
	160	alsa = sdi->priv;
	161
	162	switch (device_info_id) {
	163	case SR_DI_INSTANCE:
	164	info = sdi;
	165	break;
	166	case SR_DI_NUM_PROBES:
	167	info = GINT_TO_POINTER(NUM_PROBES);
	168	break;
	169	case SR_DI_PROBE_NAMES:
	170	info = probe_names;
	171	break;
	172	case SR_DI_CUR_SAMPLERATE:
	173	info = &alsa->cur_rate;
	174	break;
	175	// case SR_DI_PROBE_TYPE:
	176	// info = GINT_TO_POINTER(SR_PROBE_TYPE_ANALOG);
	177	// break;
	178	}
	179
	180	return info;
	181	}
	182
	183	static int hw_get_status(int device_index)
	184	{
	185	/* Avoid compiler warnings. */
	186	device_index = device_index;
	187
	188	return SR_ST_ACTIVE;
	189	}
	190
	191	static int *hw_get_capabilities(void)
	192	{
	193	return capabilities;
	194	}
	195
	196	static int hw_set_configuration(int device_index, int capability, void *value)
	197	{
	198	struct sr_device_instance *sdi;
	199	struct alsa *alsa;
	200
	201	if (!(sdi = sr_get_device_instance(device_instances, device_index)))
	202	return SR_ERR;
	203	alsa = sdi->priv;
	204
	205	switch (capability) {
	206	case SR_HWCAP_PROBECONFIG:
	207	return SR_OK;
	208	case SR_HWCAP_SAMPLERATE:
	209	alsa->cur_rate = (uint64_t ) value;
	210	return SR_OK;
	211	case SR_HWCAP_LIMIT_SAMPLES:
	212	alsa->limit_samples = (uint64_t ) value;
	213	return SR_OK;
	214	default:
	215	return SR_ERR;
	216	}
	217	}
	218
	219	static int receive_data(int fd, int revents, void *user_data)
	220	{
	221	struct sr_device_instance *sdi = user_data;
	222	struct alsa *alsa = sdi->priv;
	223	struct sr_datafeed_packet packet;
	224	struct sr_analog_sample *sample;
	225	unsigned int sample_size = sizeof(struct sr_analog_sample) +
	226	(NUM_PROBES * sizeof(struct sr_analog_probe));
	227	char *outb;
	228	char inb[4096];
	229	int i, x, count;
	230
	231	fd = fd;
	232	revents = revents;
	233
	234	do {
	235	memset(inb, 0, sizeof(inb));
	236	count = snd_pcm_readi(alsa->capture_handle, inb,
	237	MIN(4096/4, alsa->limit_samples));
	238	if (count < 1) {
	239	sr_warn("Failed to read samples");
	240	return FALSE;
	241	}
	242
	243	if (!(outb = g_try_malloc(sample_size * count))) {
	244	sr_err("alsa: %s: outb malloc failed", __func__);
	245	return FALSE;
	246	}
	247
	248	for (i = 0; i < count; i++) {
	249	sample = (struct sr_analog_sample *)
	250	(outb + (i * sample_size));
	251	sample->num_probes = NUM_PROBES;
	252
	253	for (x = 0; x < NUM_PROBES; x++) {
	254	sample->probes[x].val =
	255	(uint16_t ) (inb + (i * 4) + (x * 2));
	256	sample->probes[x].val &= ((1 << 16) - 1);
	257	sample->probes[x].res = 16;
	258	}
	259	}
	260
	261	packet.type = SR_DF_ANALOG;
	262	packet.length = count * sample_size;
	263	packet.unitsize = sample_size;
	264	packet.payload = outb;
	265	sr_session_bus(user_data, &packet);
	266	g_free(outb);
	267	alsa->limit_samples -= count;
	268
	269	} while (alsa->limit_samples > 0);
	270
	271	packet.type = SR_DF_END;
	272	sr_session_bus(user_data, &packet);
	273
	274	return TRUE;
	275	}
	276
	277	static int hw_start_acquisition(int device_index, gpointer session_device_id)
	278	{
	279	struct sr_device_instance *sdi;
	280	struct alsa *alsa;
	281	struct sr_datafeed_packet packet;
	282	struct sr_datafeed_header header;
	283	struct pollfd *ufds;
	284	int count;
	285	int err;
	286
	287	if (!(sdi = sr_get_device_instance(device_instances, device_index)))
	288	return SR_ERR;
	289	alsa = sdi->priv;
	290
	291	err = snd_pcm_hw_params_set_access(alsa->capture_handle,
	292	alsa->hw_params, SND_PCM_ACCESS_RW_INTERLEAVED);
	293	if (err < 0) {
	294	sr_warn("cannot set access type (%s)", snd_strerror(err));
	295	return SR_ERR;
	296	}
	297
	298	/* FIXME: Hardcoded for 16bits */
	299	err = snd_pcm_hw_params_set_format(alsa->capture_handle,
	300	alsa->hw_params, SND_PCM_FORMAT_S16_LE);
	301	if (err < 0) {
	302	sr_warn("cannot set sample format (%s)", snd_strerror(err));
	303	return SR_ERR;
	304	}
	305
	306	err = snd_pcm_hw_params_set_rate_near(alsa->capture_handle,
	307	alsa->hw_params, (unsigned int *) &alsa->cur_rate, 0);
	308	if (err < 0) {
	309	sr_warn("cannot set sample rate (%s)", snd_strerror(err));
	310	return SR_ERR;
	311	}
	312
	313	err = snd_pcm_hw_params_set_channels(alsa->capture_handle,
	314	alsa->hw_params, NUM_PROBES);
	315	if (err < 0) {
	316	sr_warn("cannot set channel count (%s)", snd_strerror(err));
	317	return SR_ERR;
	318	}
	319
	320	err = snd_pcm_hw_params(alsa->capture_handle, alsa->hw_params);
	321	if (err < 0) {
	322	sr_warn("cannot set parameters (%s)", snd_strerror(err));
	323	return SR_ERR;
	324	}
	325
	326	err = snd_pcm_prepare(alsa->capture_handle);
	327	if (err < 0) {
	328	sr_warn("cannot prepare audio interface for use (%s)",
	329	snd_strerror(err));
	330	return SR_ERR;
	331	}
	332
	333	count = snd_pcm_poll_descriptors_count(alsa->capture_handle);
	334	if (count < 1) {
	335	sr_warn("Unable to obtain poll descriptors count");
	336	return SR_ERR;
	337	}
	338
	339	if (!(ufds = g_try_malloc(count * sizeof(struct pollfd)))) {
	340	sr_warn("alsa: %s: ufds malloc failed", __func__);
	341	return SR_ERR_MALLOC;
	342	}
	343
	344	err = snd_pcm_poll_descriptors(alsa->capture_handle, ufds, count);
	345	if (err < 0) {
	346	sr_warn("Unable to obtain poll descriptors (%s)",
	347	snd_strerror(err));
	348	g_free(ufds);
	349	return SR_ERR;
	350	}
	351
	352	alsa->session_id = session_device_id;
	353	sr_source_add(ufds[0].fd, ufds[0].events, 10, receive_data, sdi);
	354
	355	packet.type = SR_DF_HEADER;
	356	packet.length = sizeof(struct sr_datafeed_header);
	357	packet.payload = (unsigned char *) &header;
	358	header.feed_version = 1;
	359	gettimeofday(&header.starttime, NULL);
	360	header.samplerate = alsa->cur_rate;
	361	header.num_analog_probes = NUM_PROBES;
	362	header.num_logic_probes = 0;
	363	header.protocol_id = SR_PROTO_RAW;
	364	sr_session_bus(session_device_id, &packet);
	365	g_free(ufds);
	366
	367	return SR_OK;
	368	}
	369
	370	static void hw_stop_acquisition(int device_index, gpointer session_device_id)
	371	{
	372	/* Avoid compiler warnings. */
	373	device_index = device_index;
	374	session_device_id = session_device_id;
	375	}
	376
	377	struct sr_device_plugin alsa_plugin_info = {
	378	.name = "alsa",
	379	.longname = "ALSA driver",
	380	.api_version = 1,
	381	.init = hw_init,
	382	.cleanup = hw_cleanup,
	383	.opendev = hw_opendev,
	384	.closedev = hw_closedev,
	385	.get_device_info = hw_get_device_info,
	386	.get_status = hw_get_status,
	387	.get_capabilities = hw_get_capabilities,
	388	.set_configuration = hw_set_configuration,
	389	.start_acquisition = hw_start_acquisition,
	390	.stop_acquisition = hw_stop_acquisition,
	391	};