atmel-pcm-dma.c
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/*
* 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,
.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");