iio: adc: meson: init voltage control bits

Define and init voltage configuration bits. Those bits are inited in
vendor boot code (bl2, bl33) already so do it in the driver to not depend
on other code.

Introduced bits:
REG11[0] - selects Vref. 0 - calibration voltage, 1 - VDDA. txlx and later
           SoCs support VDDA or calibration voltage as Vref, but others
           support only calibration voltage. For newer platforms vendor
	   uses VDDA as default.
REG11[1] - reserved bit. g12a and later SoCs must write 1, others SoCs
           write 0.
REG11[5] - Vref voltage. 0 - 0.9v, 1 - 1.8v. g12a and later SoCs must
           write 0, others SoCs write 1.
REG11[6] - selects common-mode voltage, 0: from AVDD, 1: from Vref.
           g12a and later SoCs must write 0, others SoCs write 1.
Signed-off-by: George Stark <gnstark@sberdevices.ru>
Link: https://lore.kernel.org/r/20230715110654.6035-4-gnstark@sberdevices.ruSigned-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

drivers/iio/adc/meson_saradc.c

@@ -156,6 +156,10 @@
  */
 #define MESON_SAR_ADC_REG11					0x2c
 	#define MESON_SAR_ADC_REG11_BANDGAP_EN			BIT(13)
+	#define MESON_SAR_ADC_REG11_CMV_SEL                     BIT(6)
+	#define MESON_SAR_ADC_REG11_VREF_VOLTAGE                BIT(5)
+	#define MESON_SAR_ADC_REG11_EOC                         BIT(1)
+	#define MESON_SAR_ADC_REG11_VREF_SEL                    BIT(0)
 
 #define MESON_SAR_ADC_REG13					0x34
 	#define MESON_SAR_ADC_REG13_12BIT_CALIBRATION_MASK	GENMASK(13, 8)
@@ -216,6 +220,11 @@
 	.datasheet_name = "SAR_ADC_MUX_"#_sel,				\
 }
 
+enum meson_sar_adc_vref_sel {
+	VREF_CALIBATION_VOLTAGE = 0,
+	VREF_VDDA = 1,
+};
+
 enum meson_sar_adc_avg_mode {
 	NO_AVERAGING = 0x0,
 	MEAN_AVERAGING = 0x1,
@@ -314,6 +323,12 @@ struct meson_sar_adc_param {
 	unsigned int				temperature_multiplier;
 	unsigned int				temperature_divider;
 	u8					disable_ring_counter;
+	bool					has_reg11;
+	bool					has_vref_select;
+	u8					vref_select;
+	u8					cmv_select;
+	u8					adc_eoc;
+	enum meson_sar_adc_vref_sel		vref_volatge;
 };
 
 struct meson_sar_adc_data {
@@ -974,6 +989,29 @@ static int meson_sar_adc_init(struct iio_dev *indio_dev)
 			   MESON_SAR_ADC_REG3_CTRL_CONT_RING_COUNTER_EN,
 			   regval);
 
+	if (priv->param->has_reg11) {
+		regval = FIELD_PREP(MESON_SAR_ADC_REG11_EOC, priv->param->adc_eoc);
+		regmap_update_bits(priv->regmap, MESON_SAR_ADC_REG11,
+				   MESON_SAR_ADC_REG11_EOC, regval);
+
+		if (priv->param->has_vref_select) {
+			regval = FIELD_PREP(MESON_SAR_ADC_REG11_VREF_SEL,
+					    priv->param->vref_select);
+			regmap_update_bits(priv->regmap, MESON_SAR_ADC_REG11,
+					   MESON_SAR_ADC_REG11_VREF_SEL, regval);
+		}
+
+		regval = FIELD_PREP(MESON_SAR_ADC_REG11_VREF_VOLTAGE,
+				    priv->param->vref_volatge);
+		regmap_update_bits(priv->regmap, MESON_SAR_ADC_REG11,
+				   MESON_SAR_ADC_REG11_VREF_VOLTAGE, regval);
+
+		regval = FIELD_PREP(MESON_SAR_ADC_REG11_CMV_SEL,
+				    priv->param->cmv_select);
+		regmap_update_bits(priv->regmap, MESON_SAR_ADC_REG11,
+				   MESON_SAR_ADC_REG11_CMV_SEL, regval);
+	}
+
 	ret = clk_set_parent(priv->adc_sel_clk, priv->clkin);
 	if (ret)
 		return dev_err_probe(dev, ret, "failed to set adc parent to clkin\n");
@@ -1195,6 +1233,9 @@ static const struct meson_sar_adc_param meson_sar_adc_gxbb_param = {
 	.bandgap_reg = MESON_SAR_ADC_REG11,
 	.regmap_config = &meson_sar_adc_regmap_config_gxbb,
 	.resolution = 10,
+	.has_reg11 = true,
+	.vref_volatge = 1,
+	.cmv_select = 1,
 };
 
 static const struct meson_sar_adc_param meson_sar_adc_gxl_param = {
@@ -1204,6 +1245,9 @@ static const struct meson_sar_adc_param meson_sar_adc_gxl_param = {
 	.regmap_config = &meson_sar_adc_regmap_config_gxbb,
 	.resolution = 12,
 	.disable_ring_counter = 1,
+	.has_reg11 = true,
+	.vref_volatge = 1,
+	.cmv_select = 1,
 };
 
 static const struct meson_sar_adc_param meson_sar_adc_g12a_param = {
@@ -1213,6 +1257,10 @@ static const struct meson_sar_adc_param meson_sar_adc_g12a_param = {
 	.regmap_config = &meson_sar_adc_regmap_config_gxbb,
 	.resolution = 12,
 	.disable_ring_counter = 1,
+	.has_reg11 = true,
+	.adc_eoc = 1,
+	.has_vref_select = true,
+	.vref_select = VREF_VDDA,
 };
 
 static const struct meson_sar_adc_data meson_sar_adc_meson8_data = {