diff options
Diffstat (limited to 'alsa.c')
| -rwxr-xr-x | alsa.c | 255 |
1 files changed, 255 insertions, 0 deletions
@@ -0,0 +1,255 @@ +// SPDX-License-Identifier: GPL-2.0+ +/* + * ALSA Virtual Soundcard + * + * alsa.c - ALSA PCM driver for virtual ALSA card + * + * Copyright (C) 2010-2018 Fiberdyne Systems Pty Ltd + */ + +#include <linux/slab.h> +#include <sound/core.h> +#include <sound/initval.h> + +#include "alsa.h" +#include "core.h" + +static struct avirt_alsa_driver *_driver = NULL; + +extern struct snd_pcm_ops pcm_ops; + +/** + * pcm_constructor - Constructs the ALSA PCM middle devices for this driver + * @card: The snd_card struct to construct the devices for + * @return 0 on success or error code otherwise + */ +static int pcm_constructor(struct snd_card *card) +{ + struct snd_pcm *pcm; + int i; + + // Allocate Playback PCM instances + for (i = 0; i < _driver->playback.devices; i++) { + CHK_ERR(snd_pcm_new(card, + _driver->playback.config[i].devicename, i, + 1, 0, &pcm)); + + /** Register driver callbacks */ + snd_pcm_set_ops(pcm, SNDRV_PCM_STREAM_PLAYBACK, &pcm_ops); + + pcm->info_flags = 0; + strcpy(pcm->name, _driver->playback.config[i].devicename); + } + + // Allocate Capture PCM instances + for (i = 0; i < _driver->capture.devices; i++) { + CHK_ERR(snd_pcm_new(card, _driver->capture.config[i].devicename, + i, 0, 1, &pcm)); + + /** Register driver callbacks */ + snd_pcm_set_ops(pcm, SNDRV_PCM_STREAM_CAPTURE, &pcm_ops); + + pcm->info_flags = 0; + strcpy(pcm->name, _driver->capture.config[i].devicename); + } + + return 0; +} + +/** + * alloc_dev_config - Allocates memory for ALSA device configuration + * @return: 0 on success or error code otherwise + */ +static int alloc_dev_config(struct avirt_alsa_dev_config **devconfig, + struct avirt_alsa_dev_config *userconfig, + unsigned numdevices) +{ + if (numdevices == 0) + return 0; + + *devconfig = kzalloc(sizeof(struct avirt_alsa_dev_config) * numdevices, + GFP_KERNEL); + if (!(*devconfig)) + return -ENOMEM; + + memcpy(*devconfig, userconfig, + sizeof(struct avirt_alsa_dev_config) * numdevices); + + return 0; +} + +/** + * alloc_dev_streams - Initializes ALSA device substream buffers + * @return: 0 on success or error code otherwise + */ +static int alloc_dev_streams(struct avirt_alsa_dev_config *config, + struct avirt_alsa_stream **streams, + unsigned numdevices) +{ + unsigned i; + + if (numdevices == 0) + return 0; + + *streams = kzalloc(sizeof(struct avirt_alsa_stream) * numdevices, + GFP_KERNEL); + + if (!(*streams)) + return -EFAULT; + + for (i = 0; i < numdevices; i++) + (*streams)[i].hw_frame_idx = 0; + + return 0; +} + +struct avirt_alsa_dev_group *avirt_alsa_get_dev_group(int direction) +{ + if (!_driver) { + pr_err("[%s] _driver is NULL", __func__); + return NULL; + } + + switch (direction) { + case SNDRV_PCM_STREAM_PLAYBACK: + return &_driver->playback; + case SNDRV_PCM_STREAM_CAPTURE: + return &_driver->capture; + default: + pr_err("[%s] Direction must be SNDRV_PCM_STREAM_XXX!", + __func__); + return NULL; + } +} + +/** + * avirt_alsa_init - Initializes the ALSA driver + * @return: 0 on success or error code otherwise + */ +int avirt_alsa_init() +{ + // Allocate memory for the driver + _driver = kzalloc(sizeof(struct avirt_alsa_driver), GFP_KERNEL); + if (!_driver) + return -ENOMEM; + + return 0; +} + +/** + * avirt_alsa_configure_pcm- Configure the PCM device + * @config: Device configuration structure array + * @direction: Direction of PCM (SNDRV_PCM_STREAM_XXX) + * @numdevices: Number of devices (array length) + * @return: 0 on success or error code otherwise + */ +int avirt_alsa_configure_pcm(struct avirt_alsa_dev_config *config, + int direction, unsigned numdevices) +{ + struct avirt_alsa_dev_group *group; + + group = avirt_alsa_get_dev_group(direction); + CHK_NULL(group); + + CHK_ERR(alloc_dev_config(&group->config, config, numdevices)); + + group->devices = numdevices; + + CHK_ERR(alloc_dev_streams(group->config, &group->streams, + group->devices)); + return 0; +} + +/** + * avirt_alsa_register - Registers the ALSA driver + * @devptr: Platform driver device + * @return: 0 on success or error code otherwise + */ +int avirt_alsa_register(struct platform_device *devptr) +{ + struct snd_card *card; + static struct snd_device_ops device_ops; + + if (!_driver) + return -EFAULT; + + // Create the card instance + CHK_ERR_V(snd_card_new(&devptr->dev, SNDRV_DEFAULT_IDX1, "avirt", + THIS_MODULE, 0, &card), + "Failed to create sound card"); + + strcpy(card->driver, "avirt-alsa-device"); + strcpy(card->shortname, "avirt"); + strcpy(card->longname, "A virtual sound card driver for ALSA"); + _driver->card = card; + + // Create new sound device + CHK_ERR_V((snd_device_new(card, SNDRV_DEV_LOWLEVEL, _driver, + &device_ops)), + "Failed to create sound device"); + + CHK_ERR((pcm_constructor(card))); + + /** Register with the ALSA framework */ + CHK_ERR_V(snd_card_register(card), "Device registration failed"); + + return 0; +} + +/** + * avirt_alsa_deregister - Deregisters the ALSA driver + * @devptr: Platform driver device + * @return: 0 on success or error code otherwise + */ +int avirt_alsa_deregister(void) +{ + snd_card_free(_driver->card); + + if (_driver->playback.config) + kfree(_driver->playback.config); + if (_driver->playback.streams) + kfree(_driver->playback.streams); + if (_driver->capture.config) + kfree(_driver->capture.config); + if (_driver->capture.streams) + kfree(_driver->capture.streams); + + kfree(_driver); + + return 0; +} + +/** + * pcm_buff_complete_cb - PCM buffer complete callback + * @substreamid: pointer to ALSA PCM substream + * @return 0 on success or error code otherwise + * + * This should be called from a child Audio Path once it has finished processing + * the pcm buffer + */ +int pcm_buff_complete_cb(struct snd_pcm_substream *substream) +{ + int maxframe, deviceid; + struct avirt_audiopath *audiopath; + struct avirt_alsa_dev_group *group; + + deviceid = substream->pcm->device; + + group = avirt_alsa_get_dev_group(substream->stream); + CHK_NULL(group); + + audiopath = avirt_get_current_audiopath(); + CHK_NULL_V(audiopath, "Cannot find Audio Path!"); + + group->streams[deviceid].hw_frame_idx += audiopath->blocksize; + maxframe = audiopath->blocksize * audiopath->hw->periods_max; + + // Once the index reaches the DMA buffer boundary, reset it to 0 + if (group->streams[deviceid].hw_frame_idx >= maxframe) + group->streams[deviceid].hw_frame_idx = 0; + + // Notify ALSA middle layer of the elapsed period boundary + snd_pcm_period_elapsed(group->streams[deviceid].substream); + + return 0; +} |