ASoC: davinci-mcasp: Implement configurable dismod handling

If the dismod is specified in the DT node, use the specified custom value
to configure the drive on state of the inactive TX slots.

If the dismod is not present or booted in legacy mode, the dismod is set
to low as it was the original behavior.

Signed-off-by: Peter Ujfalusi <[e-mail]>
Signed-off-by: Mark Brown <[e-mail]>

include/linux/platform_data/davinci_asp.h

···
 	/* McASP specific fields */
 	int tdm_slots;
 	u8 op_mode;
+	u8 dismod;
 	u8 num_serializer;
 	u8 *serial_dir;
 	u8 version;

sound/soc/davinci/davinci-mcasp.c

···
 	u32	tdm_mask[2];
 	int	slot_width;
 	u8	op_mode;
+	u8	dismod;
 	u8	num_serializer;
 	u8	*serial_dir;
 	u8	version;
···
 		if (mcasp->serial_dir[i] == TX_MODE &&
 					tx_ser < max_active_serializers) {
 			mcasp_mod_bits(mcasp, DAVINCI_MCASP_XRSRCTL_REG(i),
-				       DISMOD_LOW, DISMOD_MASK);
+				       mcasp->dismod, DISMOD_MASK);
 			set_bit(PIN_BIT_AXR(i), &mcasp->pdir);
 			tx_ser++;
 		} else if (mcasp->serial_dir[i] == RX_MODE &&
···
 			clear_bit(PIN_BIT_AXR(i), &mcasp->pdir);
 		} else if (mcasp->serial_dir[i] == TX_MODE) {
 			/* Unused TX pins, clear PDIR  */
+			mcasp_mod_bits(mcasp, DAVINCI_MCASP_XRSRCTL_REG(i),
+				       mcasp->dismod, DISMOD_MASK);
 			clear_bit(PIN_BIT_AXR(i), &mcasp->pdir);
 		}
 	}
···
 
 	if (pdev->dev.platform_data) {
 		pdata = pdev->dev.platform_data;
+		pdata->dismod = DISMOD_LOW;
 		return pdata;
 	} else if (match) {
 		pdata = devm_kmemdup(&pdev->dev, match->data, sizeof(*pdata),
···
 	ret = of_property_read_u32(np, "sram-size-capture", &val);
 	if (ret >= 0)
 		pdata->sram_size_capture = val;
+
+	ret = of_property_read_u32(np, "dismod", &val);
+	if (ret >= 0) {
+		if (val == 0 || val == 2 || val == 3) {
+			pdata->dismod = DISMOD_VAL(val);
+		} else {
+			dev_warn(&pdev->dev, "Invalid dismod value: %u\n", val);
+			pdata->dismod = DISMOD_LOW;
+		}
+	} else {
+		pdata->dismod = DISMOD_LOW;
+	}
 
 	return  pdata;
 
···
 	mcasp->version = pdata->version;
 	mcasp->txnumevt = pdata->txnumevt;
 	mcasp->rxnumevt = pdata->rxnumevt;
+	mcasp->dismod = pdata->dismod;
 
 	mcasp->dev = &pdev->dev;
 

sound/soc/davinci/davinci-mcasp.h

···
 #define DISMOD_3STATE	(0x0)
 #define DISMOD_LOW	(0x2 << 2)
 #define DISMOD_HIGH	(0x3 << 2)
+#define DISMOD_VAL(x)	((x) << 2)
 #define DISMOD_MASK	DISMOD_HIGH
 #define TXSTATE		BIT(4)
 #define RXSTATE		BIT(5)