Quelle  sdma-pcm.c   Sprache: C

// SPDX-License-Identifier: GPL-2.0
/*
 *  Copyright (C) 2018 Texas Instruments Incorporated - https://www.ti.com
 *  Author: Peter Ujfalusi <peter.ujfalusi@ti.com>
 */

#include <linux/device.h>
#include <linux/module.h>
#include <sound/core.h>
#include <sound/pcm.h>
#include <sound/pcm_params.h>
#include <sound/soc.h>
#include <sound/dmaengine_pcm.h>

#include "sdma-pcm.h"

static const struct snd_pcm_hardware sdma_pcm_hardware = {
 .info   = SNDRV_PCM_INFO_MMAP |
      SNDRV_PCM_INFO_MMAP_VALID |
      SNDRV_PCM_INFO_PAUSE | SNDRV_PCM_INFO_RESUME |
      SNDRV_PCM_INFO_NO_PERIOD_WAKEUP |
      SNDRV_PCM_INFO_INTERLEAVED,
 .period_bytes_min = 32,
 .period_bytes_max = 64 * 1024,
 .buffer_bytes_max = 128 * 1024,
 .periods_min  = 2,
 .periods_max  = 255,
};

static const struct snd_dmaengine_pcm_config sdma_dmaengine_pcm_config = {
 .pcm_hardware = &sdma_pcm_hardware,
 .prepare_slave_config = snd_dmaengine_pcm_prepare_slave_config,
 .prealloc_buffer_size = 128 * 1024,
};

int sdma_pcm_platform_register(struct device *dev,
          char *txdmachan, char *rxdmachan)
{
 struct snd_dmaengine_pcm_config *config;
 unsigned int flags = 0;

 /* Standard names for the directions: 'tx' and 'rx' */
 if (!txdmachan && !rxdmachan)
  return devm_snd_dmaengine_pcm_register(dev,
      &sdma_dmaengine_pcm_config, 0);

 config = devm_kzalloc(dev, sizeof(*config), GFP_KERNEL);
 if (!config)
  return -ENOMEM;

 *config = sdma_dmaengine_pcm_config;

 if (!txdmachan || !rxdmachan) {
  /* One direction only PCM */
  flags |= SND_DMAENGINE_PCM_FLAG_HALF_DUPLEX;
  if (!txdmachan) {
   txdmachan = rxdmachan;
   rxdmachan = NULL;
  }
 }

 config->chan_names[0] = txdmachan;
 config->chan_names[1] = rxdmachan;

 return devm_snd_dmaengine_pcm_register(dev, config, flags);
}
EXPORT_SYMBOL_GPL(sdma_pcm_platform_register);

MODULE_AUTHOR("Peter Ujfalusi ");
MODULE_DESCRIPTION("sDMA PCM ASoC platform driver");
MODULE_LICENSE("GPL v2");