ASoC: ux500: Add DMA slave config prepare routine

Implement a DMA slave config prepare routine, as until now the MSP
driver depended on the DMA controller completing the channel
configuration on its own, but this is not the case anymore since the
recent DMA driver updates.
Signed-off-by: Fabio Baltieri <fabio.baltieri@linaro.org>
Acked-by: Linus Walleij <linus.walleij@linaro.org>
Acked-by: Lee Jones <lee.jones@linaro.org>
Signed-off-by: Mark Brown <broonie@linaro.org>

sound/soc/ux500/ux500_pcm.c

@@ -103,10 +103,40 @@ static struct dma_chan *ux500_pcm_request_chan(struct snd_soc_pcm_runtime *rtd,
 	return snd_dmaengine_pcm_request_channel(stedma40_filter, dma_cfg);
 }
 
+static int ux500_pcm_prepare_slave_config(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 ux500_msp_dma_params *dma_params;
+	struct stedma40_chan_cfg *dma_cfg;
+	int ret;
+
+	dma_params = snd_soc_dai_get_dma_data(rtd->cpu_dai, substream);
+	dma_cfg = dma_params->dma_cfg;
+
+	ret = snd_hwparams_to_dma_slave_config(substream, params, slave_config);
+	if (ret)
+		return ret;
+
+	slave_config->dst_maxburst = 4;
+	slave_config->dst_addr_width = dma_cfg->dst_info.data_width;
+	slave_config->src_maxburst = 4;
+	slave_config->src_addr_width = dma_cfg->src_info.data_width;
+
+	if (substream->stream == SNDRV_PCM_STREAM_PLAYBACK)
+		slave_config->dst_addr = dma_params->tx_rx_addr;
+	else
+		slave_config->src_addr = dma_params->tx_rx_addr;
+
+	return 0;
+}
+
 static const struct snd_dmaengine_pcm_config ux500_dmaengine_pcm_config = {
 	.pcm_hardware = &ux500_pcm_hw,
 	.compat_request_channel = ux500_pcm_request_chan,
 	.prealloc_buffer_size = 128 * 1024,
+	.prepare_slave_config = ux500_pcm_prepare_slave_config,
 };
 
 int ux500_pcm_register_platform(struct platform_device *pdev)