iio: sx9324: Add setting for CS idle mode

Based on device tree setting, set the CS idle mode.
Reviewed-by: Gwendal Grignou <gwendal@chromium.org>
Signed-off-by: Stephen Boyd <swboyd@chromium.org>
Link: https://lore.kernel.org/r/20220503193937.3794477-3-swboyd@chromium.orgSigned-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

drivers/iio/proximity/sx9324.c

@@ -57,6 +57,11 @@
 	GENMASK(SX9324_REG_AFE_CTRL0_RINT_SHIFT + 1, \
 		SX9324_REG_AFE_CTRL0_RINT_SHIFT)
 #define SX9324_REG_AFE_CTRL0_RINT_LOWEST	0x00
+#define SX9324_REG_AFE_CTRL0_CSIDLE_SHIFT	4
+#define SX9324_REG_AFE_CTRL0_CSIDLE_MASK \
+	GENMASK(SX9324_REG_AFE_CTRL0_CSIDLE_SHIFT + 1, \
+		SX9324_REG_AFE_CTRL0_CSIDLE_SHIFT)
+#define SX9324_REG_AFE_CTRL0_RINT_LOWEST	0x00
 #define SX9324_REG_AFE_CTRL1		0x21
 #define SX9324_REG_AFE_CTRL2		0x22
 #define SX9324_REG_AFE_CTRL3		0x23
@@ -872,6 +877,8 @@ sx9324_get_default_reg(struct device *dev, int idx,
 {
 	static const char * const sx9324_rints[] = { "lowest", "low", "high",
 		"highest" };
+	static const char * const sx9324_csidle[] = { "hi-z", "hi-z", "gnd",
+		"vdd" };
 #define SX9324_PIN_DEF "semtech,ph0-pin"
 #define SX9324_RESOLUTION_DEF "semtech,ph01-resolution"
 #define SX9324_PROXRAW_DEF "semtech,ph01-proxraw-strength"
@@ -901,6 +908,15 @@ sx9324_get_default_reg(struct device *dev, int idx,
 		reg_def->def = raw;
 		break;
 	case SX9324_REG_AFE_CTRL0:
+		ret = device_property_read_string(dev,
+				"semtech,cs-idle-sleep", &res);
+		if (!ret)
+			ret = match_string(sx9324_csidle, ARRAY_SIZE(sx9324_csidle), res);
+		if (ret >= 0) {
+			reg_def->def &= ~SX9324_REG_AFE_CTRL0_CSIDLE_MASK;
+			reg_def->def |= ret << SX9324_REG_AFE_CTRL0_CSIDLE_SHIFT;
+		}
+
 		ret = device_property_read_string(dev,
 				"semtech,int-comp-resistor", &res);
 		if (ret)