/*
* Stop circular DMA descriptor list
* We should not stop DMA in a middle of current transaction once we receive
* stop request from ALSA core. This function finds the next DMA descriptor
* and set it up to decrement DMA channel semaphore. So the current transaction
* is the last data transfer.
*/
static void mxs_pcm_stop(struct snd_pcm_substream *substream)
{
struct snd_pcm_runtime *runtime = substream->runtime;
struct mxs_runtime_data *prtd = runtime->private_data;
struct mxs_dma_info dma_info;
int desc;
int periods_num = prtd->dma_totsize / prtd->dma_period;
/* Freez DMA channel for a moment */
mxs_dma_freeze(prtd->dma_ch);
mxs_dma_get_info(prtd->dma_ch, &dma_info);
desc = (dma_info.buf_addr - runtime->dma_addr) / prtd->dma_period;
if (desc >= periods_num)
desc = 0;
else if (desc < 0)
desc = 0;
/* Set up the next descriptor to decrement DMA channel sempahore */
prtd->dma_desc_array[(desc + 1)%periods_num]->cmd.cmd.bits.bytes = 0;
prtd->dma_desc_array[(desc + 1)%periods_num]->cmd.cmd.bits.pio_words = \
0;
prtd->dma_desc_array[(desc + 1)%periods_num]->cmd.cmd.bits.dec_sem = 1;
prtd->dma_desc_array[(desc + 1)%periods_num]->cmd.cmd.bits.irq = 0;
prtd->dma_desc_array[(desc + 1)%periods_num]->cmd.cmd.bits.command = \
NO_DMA_XFER;
mxs_dma_unfreeze(prtd->dma_ch);
mxs_dma_disable(prtd->dma_ch);
}
static int mxs_pcm_trigger(struct snd_pcm_substream *substream, int cmd)
{
struct snd_pcm_runtime *runtime = substream->runtime;
struct mxs_runtime_data *prtd = substream->runtime->private_data;
int ret = 0;
switch (cmd) {
case SNDRV_PCM_TRIGGER_START:
if ((prtd->params->dma_ch == MXS_DMA_CHANNEL_AHB_APBX_SPDIF) &&
(substream->stream == SNDRV_PCM_STREAM_PLAYBACK) &&
(runtime->access == SNDRV_PCM_ACCESS_MMAP_INTERLEAVED) &&
((prtd->format == SNDRV_PCM_FORMAT_S24_LE)
|| (prtd->format == SNDRV_PCM_FORMAT_S20_3LE))) {
prtd->appl_ptr_bytes =
frames_to_bytes(runtime,
runtime->control->appl_ptr);
memmove(runtime->dma_area + 1, runtime->dma_area,
prtd->appl_ptr_bytes - 1);
}
mxs_dma_enable(prtd->dma_ch);
break;
case SNDRV_PCM_TRIGGER_STOP:
mxs_pcm_stop(substream);
break;
case SNDRV_PCM_TRIGGER_RESUME:
case SNDRV_PCM_TRIGGER_PAUSE_RELEASE:
mxs_dma_unfreeze(prtd->dma_ch);
break;
case SNDRV_PCM_TRIGGER_SUSPEND:
case SNDRV_PCM_TRIGGER_PAUSE_PUSH:
mxs_dma_freeze(prtd->dma_ch);
break;
default:
ret = -EINVAL;
break;
}
return ret;
}