ASoC: SDCA: Fix some holes in the regmap readable/writeable helpers

The current regmap readable/writeable helper functions always
allow the Next flag and allows any Control Number. Mask the Next
flag based on SDCA_ACCESS_MODE_DUAL which is the only Mode that
supports it. Also check that the Control Number is valid for
the given control.

Fixes: e3f7caf ("ASoC: SDCA: Add generic regmap SDCA helpers")
Signed-off-by: Charles Keepax <ckeepax@opensource.cirrus.com>
Link: https://patch.msgid.link/20250718135432.1048566-2-ckeepax@opensource.cirrus.com
Signed-off-by: Mark Brown <broonie@kernel.org>

Author: charleskeepax

sound/soc/sdca/sdca_regmap.c

@@ -72,12 +72,18 @@ bool sdca_regmap_readable(struct sdca_function_data *function, unsigned int reg)
 	if (!control)
 		return false;
 
+	if (!(BIT(SDW_SDCA_CTL_CNUM(reg)) & control->cn_list))
+		return false;
+
 	switch (control->mode) {
 	case SDCA_ACCESS_MODE_RW:
 	case SDCA_ACCESS_MODE_RO:
-	case SDCA_ACCESS_MODE_DUAL:
 	case SDCA_ACCESS_MODE_RW1S:
 	case SDCA_ACCESS_MODE_RW1C:
+		if (SDW_SDCA_NEXT_CTL(0) & reg)
+			return false;
+		fallthrough;
+	case SDCA_ACCESS_MODE_DUAL:
 		/* No access to registers marked solely for device use */
 		return control->layers & ~SDCA_ACCESS_LAYER_DEVICE;
 	default:
@@ -104,11 +110,17 @@ bool sdca_regmap_writeable(struct sdca_function_data *function, unsigned int reg
 	if (!control)
 		return false;
 
+	if (!(BIT(SDW_SDCA_CTL_CNUM(reg)) & control->cn_list))
+		return false;
+
 	switch (control->mode) {
 	case SDCA_ACCESS_MODE_RW:
-	case SDCA_ACCESS_MODE_DUAL:
 	case SDCA_ACCESS_MODE_RW1S:
 	case SDCA_ACCESS_MODE_RW1C:
+		if (SDW_SDCA_NEXT_CTL(0) & reg)
+			return false;
+		fallthrough;
+	case SDCA_ACCESS_MODE_DUAL:
 		/* No access to registers marked solely for device use */
 		return control->layers & ~SDCA_ACCESS_LAYER_DEVICE;
 	default: