drivers: sdma: Set watermark level for PDM

In order to enable PDM we need to use Multi-fifo support
and mcu_2_sai RAM script.

This script defines watermark level as follows:

r7 = Watermark
    bit0~11: watermark level(wml*fifo_number)
    bit15~12: to do-fifo number
    bit16~19: fifo offset
    bit27~24: sw done selector
    bit28~31: # audio channels in one frame, 0: 1 channel,1: 2 channels
    bit23: sw done enabled

Configuration parameters should come from DAI (PDM in our specific case)
but there is no easy way to forward such information so we just make
use of some default configuration, 4 fifos, 1 channel per fifo, sw done
enabled.

Signed-off-by: Daniel Baluta <[email protected]>

src/drivers/imx/sdma.c

@@ -69,6 +69,9 @@ struct sdma_chan {
 	int next_bd;
 	int sdma_chan_type;
 	int fifo_paddr;
+
+	unsigned int watermark_level;
+	unsigned int sw_done_sel; /* software done selector */
 };
 
 /* Private data for the whole controller */
@@ -603,6 +606,47 @@ static int sdma_status(struct dma_chan_data *channel,
 	return 0;
 }
 
+static void sdma_set_watermarklevel(struct dma_chan_data *chan)
+{
+	struct sdma_chan *pdata = dma_chan_get_data(chan);
+
+	/* TODO: retrieve this information from DAI */
+	unsigned int n_fifos = 4; /* number of HW fifos used */
+	unsigned int words_per_fifo = 1; /* number of audio channels per frame */
+
+	/* sw_done_sel mimics software done configuration from Linux
+	 * see Documentation/devicetree/bindings/fsl-imx-sdma.txt
+	 */
+	unsigned int sw_done_sel = 0;
+
+	/* sw_done_sel configuration
+	 * - bit31:  sw_done
+	 * - bit15:8 selector
+	 * - bit7-0  priority
+	 */
+	sw_done_sel |= BIT(31);
+
+	/* watermark level:
+	 * bit0~11: wartermark level(wml*fifo_number)
+	 * bit15~12: to do-fifo number
+	 * bit16~19: fifo offset
+	 * bit27~24: sw done selector
+	 * bit28~31: numbers of audio channels in one frame, 0: 1 channel,1: 2 channels
+	 * bit23: sw done enable
+	 */
+
+	pdata->watermark_level |= SDMA_WATERMARK_LEVEL_SW_DONE |
+		 (sw_done_sel & 0xff) << SDMA_WATERMARK_LEVEL_SW_DONE_SEL_OFF;
+
+	pdata->watermark_level |=
+		SDMA_WATERMARK_LEVEL_N_FIFOS(n_fifos);
+
+	pdata->watermark_level |=
+		SDMA_WATERMARK_LEVEL_WORDS_PER_FIFO(words_per_fifo - 1);
+
+	pdata->sw_done_sel = sw_done_sel;
+}
+
 static int sdma_read_config(struct dma_chan_data *channel,
 			    struct dma_sg_config *config)
 {
@@ -779,6 +823,13 @@ static int sdma_prep_desc(struct dma_chan_data *channel,
 
 	watermark = (config->burst_elems * width) / 8;
 
+	if (pdata->sdma_chan_type == SDMA_CHAN_TYPE_SAI2MCU) {
+		sdma_set_watermarklevel(channel);
+		watermark |= pdata->watermark_level;
+	} else {
+		watermark = (config->burst_elems * width) / 8;
+	}
+
 	memset(pdata->ctx, 0, sizeof(*pdata->ctx));
 	pdata->ctx->pc = sdma_script_addr;
 

src/include/sof/drivers/sdma.h

@@ -89,6 +89,12 @@
 #define SDMA_DONE0_CONFIG	0x1000
 #define SDMA_DONE1_CONFIG	0x1004
 
+#define SDMA_WATERMARK_LEVEL_N_FIFOS(x)		SET_BITS(15, 12, x)
+#define SDMA_WATERMARK_LEVEL_OFF_FIFOS(x)	SET_BITS(19, 16, x)
+#define SDMA_WATERMARK_LEVEL_WORDS_PER_FIFO(x)	SET_BITS(31, 28, x)
+#define SDMA_WATERMARK_LEVEL_SW_DONE		BIT(23)
+#define SDMA_WATERMARK_LEVEL_SW_DONE_SEL_OFF	24
+
 /* Buffer descriptor first word */
 /* Count: Data buffer size, in words */
 #define SDMA_BD_COUNT_MASK	MASK(15, 0)