text: /*
   * atmel-pcm-dma.c  --  ALSA PCM DMA support for the Atmel SoC.
   *
   *  Copyright (C) 2012 Atmel
   *
   * Author: Bo Shen <voice.shen@atmel.com>
   *
   * Based on atmel-pcm by:
   * Sedji Gaouaou <sedji.gaouaou@atmel.com>
   * Copyright 2008 Atmel
   *
   * 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., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
   */
  
  #include <linux/module.h>
  #include <linux/init.h>
  #include <linux/platform_device.h>
  #include <linux/slab.h>
  #include <linux/dma-mapping.h>
  #include <linux/dmaengine.h>
  #include <linux/atmel-ssc.h>
  #include <linux/platform_data/dma-atmel.h>
  
  #include <sound/core.h>
  #include <sound/pcm.h>
  #include <sound/pcm_params.h>
  #include <sound/soc.h>
  #include <sound/dmaengine_pcm.h>
  
  #include "atmel-pcm.h"
  
  /*--------------------------------------------------------------------------*\
   * Hardware definition
  \*--------------------------------------------------------------------------*/
  static const struct snd_pcm_hardware atmel_pcm_dma_hardware = {
  	.info			= SNDRV_PCM_INFO_MMAP |
  				  SNDRV_PCM_INFO_MMAP_VALID |
  				  SNDRV_PCM_INFO_INTERLEAVED |
  				  SNDRV_PCM_INFO_RESUME |
  				  SNDRV_PCM_INFO_PAUSE,
  	.formats		= SNDRV_PCM_FMTBIT_S16_LE,
  	.period_bytes_min	= 256,		/* lighting DMA overhead */
  	.period_bytes_max	= 2 * 0xffff,	/* if 2 bytes format */
  	.periods_min		= 8,
  	.periods_max		= 1024,		/* no limit */
  	.buffer_bytes_max	= ATMEL_SSC_DMABUF_SIZE,
  };
  
  /**
   * atmel_pcm_dma_irq: SSC interrupt handler for DMAENGINE enabled SSC
   *
   * We use DMAENGINE to send/receive data to/from SSC so this ISR is only to
   * check if any overrun occured.
   */
  static void atmel_pcm_dma_irq(u32 ssc_sr,
  	struct snd_pcm_substream *substream)
  {
  	struct snd_soc_pcm_runtime *rtd = substream->private_data;
  	struct atmel_pcm_dma_params *prtd;
  
  	prtd = snd_soc_dai_get_dma_data(rtd->cpu_dai, substream);
  
  	if (ssc_sr & prtd->mask->ssc_error) {
  		if (snd_pcm_running(substream))
  			pr_warn("atmel-pcm: buffer %s on %s (SSC_SR=%#x)\n",
  				substream->stream == SNDRV_PCM_STREAM_PLAYBACK
  				? "underrun" : "overrun", prtd->name,
  				ssc_sr);
  
  		/* stop RX and capture: will be enabled again at restart */
  		ssc_writex(prtd->ssc->regs, SSC_CR, prtd->mask->ssc_disable);
  		snd_pcm_stream_lock(substream);
  		snd_pcm_stop(substream, SNDRV_PCM_STATE_XRUN);
  		snd_pcm_stream_unlock(substream);
  
  		/* now drain RHR and read status to remove xrun condition */
  		ssc_readx(prtd->ssc->regs, SSC_RHR);
  		ssc_readx(prtd->ssc->regs, SSC_SR);
  	}
  }
  
  static int atmel_pcm_configure_dma(struct snd_pcm_substream *substream,
  	struct snd_pcm_hw_params *params, struct dma_slave_config *slave_config)
  {
  	struct snd_soc_pcm_runtime *rtd = substream->private_data;
  	struct atmel_pcm_dma_params *prtd;
  	struct ssc_device *ssc;
  	int ret;
  
  	prtd = snd_soc_dai_get_dma_data(rtd->cpu_dai, substream);
  	ssc = prtd->ssc;
  
  	ret = snd_hwparams_to_dma_slave_config(substream, params, slave_config);
  	if (ret) {
  		pr_err("atmel-pcm: hwparams to dma slave configure failed\n");
  		return ret;
  	}
  
  	if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK) {
  		slave_config->dst_addr = ssc->phybase + SSC_THR;
  		slave_config->dst_maxburst = 1;
  	} else {
  		slave_config->src_addr = ssc->phybase + SSC_RHR;
  		slave_config->src_maxburst = 1;
  	}
  
  	prtd->dma_intr_handler = atmel_pcm_dma_irq;
  
  	return 0;
  }
  
  static const struct snd_dmaengine_pcm_config atmel_dmaengine_pcm_config = {
  	.prepare_slave_config = atmel_pcm_configure_dma,
  	.pcm_hardware = &atmel_pcm_dma_hardware,
  	.prealloc_buffer_size = ATMEL_SSC_DMABUF_SIZE,
  };
  
  int atmel_pcm_dma_platform_register(struct device *dev)
  {
  	return snd_dmaengine_pcm_register(dev, &atmel_dmaengine_pcm_config,
  			SND_DMAENGINE_PCM_FLAG_NO_RESIDUE);
  }
  EXPORT_SYMBOL(atmel_pcm_dma_platform_register);
  
  void atmel_pcm_dma_platform_unregister(struct device *dev)
  {
  	snd_dmaengine_pcm_unregister(dev);
  }
  EXPORT_SYMBOL(atmel_pcm_dma_platform_unregister);
  
  MODULE_AUTHOR("Bo Shen <voice.shen@atmel.com>");
  MODULE_DESCRIPTION("Atmel DMA based PCM module");
  MODULE_LICENSE("GPL");
  