ASoC: dmaengine_pcm: Add port_window_size to DAI dma data struct

The port_window_size is a struct member of dma slave channel runtime
config. It's the length of the register area in words the data need to
be accessed on the device side. It is only used for devices which is
using an area instead of a single register to send or receive the data.
Typically the DMA loops in this area in order to transfer the data.

It's useful for cases that reading/writing multiple registers in DMA
transactions.

Signed-off-by: Chancel Liu <[e-mail]>
Link: https://patch.msgid.link/[e-mail]
Signed-off-by: Mark Brown <[e-mail]>

include/sound/dmaengine_pcm.h

···
  * @peripheral_config: peripheral configuration for programming peripheral
  * for dmaengine transfer
  * @peripheral_size: peripheral configuration buffer size
+ * @port_window_size: The length of the register area in words the data need
+ * to be accessed on the device side. It is only used for devices which is using
+ * an area instead of a single register to send/receive the data. Typically the
+ * DMA loops in this area in order to transfer the data.
  */
 struct snd_dmaengine_dai_dma_data {
 	dma_addr_t addr;
···
 	unsigned int flags;
 	void *peripheral_config;
 	size_t peripheral_size;
+	u32 port_window_size;
 };
 
 void snd_dmaengine_pcm_set_config_from_dai_data(

sound/core/pcm_dmaengine.c

···
 	if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK) {
 		slave_config->dst_addr = dma_data->addr;
 		slave_config->dst_maxburst = dma_data->maxburst;
+		slave_config->dst_port_window_size = dma_data->port_window_size;
 		if (dma_data->flags & SND_DMAENGINE_PCM_DAI_FLAG_PACK)
 			slave_config->dst_addr_width =
 				DMA_SLAVE_BUSWIDTH_UNDEFINED;
···
 	} else {
 		slave_config->src_addr = dma_data->addr;
 		slave_config->src_maxburst = dma_data->maxburst;
+		slave_config->src_port_window_size = dma_data->port_window_size;
 		if (dma_data->flags & SND_DMAENGINE_PCM_DAI_FLAG_PACK)
 			slave_config->src_addr_width =
 				DMA_SLAVE_BUSWIDTH_UNDEFINED;