iio: adc: meson-saradc: initialize the bandgap correctly on older SoCs

Meson8 and Meson8b do not have the MESON_SAR_ADC_REG11 register. The
bandgap setting for these SoCs is configured in the
MESON_SAR_ADC_DELTA_10 register instead.
Make the driver aware of this difference and use the correct bandgap
register depending on the SoC.
This has worked fine on Meson8 and Meson8b because the bootloader is
already initializing the bandgap setting.

Fixes: 6c76ed3 ("iio: adc: meson-saradc: add Meson8b SoC compatibility")
Signed-off-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
Cc: <Stable@vger.kernel.org>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

drivers/iio/adc/meson_saradc.c

@@ -221,6 +221,7 @@ enum meson_sar_adc_chan7_mux_sel {
 
 struct meson_sar_adc_data {
 	bool					has_bl30_integration;
+	u32					bandgap_reg;
 	unsigned int				resolution;
 	const char				*name;
 };
@@ -685,6 +686,20 @@ static int meson_sar_adc_init(struct iio_dev *indio_dev)
 	return 0;
 }
 
+static void meson_sar_adc_set_bandgap(struct iio_dev *indio_dev, bool on_off)
+{
+	struct meson_sar_adc_priv *priv = iio_priv(indio_dev);
+	u32 enable_mask;
+
+	if (priv->data->bandgap_reg == MESON_SAR_ADC_REG11)
+		enable_mask = MESON_SAR_ADC_REG11_BANDGAP_EN;
+	else
+		enable_mask = MESON_SAR_ADC_DELTA_10_TS_VBG_EN;
+
+	regmap_update_bits(priv->regmap, priv->data->bandgap_reg, enable_mask,
+			   on_off ? enable_mask : 0);
+}
+
 static int meson_sar_adc_hw_enable(struct iio_dev *indio_dev)
 {
 	struct meson_sar_adc_priv *priv = iio_priv(indio_dev);
@@ -717,9 +732,9 @@ static int meson_sar_adc_hw_enable(struct iio_dev *indio_dev)
 	regval = FIELD_PREP(MESON_SAR_ADC_REG0_FIFO_CNT_IRQ_MASK, 1);
 	regmap_update_bits(priv->regmap, MESON_SAR_ADC_REG0,
 			   MESON_SAR_ADC_REG0_FIFO_CNT_IRQ_MASK, regval);
-	regmap_update_bits(priv->regmap, MESON_SAR_ADC_REG11,
-			   MESON_SAR_ADC_REG11_BANDGAP_EN,
-			   MESON_SAR_ADC_REG11_BANDGAP_EN);
+
+	meson_sar_adc_set_bandgap(indio_dev, true);
+
 	regmap_update_bits(priv->regmap, MESON_SAR_ADC_REG3,
 			   MESON_SAR_ADC_REG3_ADC_EN,
 			   MESON_SAR_ADC_REG3_ADC_EN);
@@ -739,8 +754,7 @@ static int meson_sar_adc_hw_enable(struct iio_dev *indio_dev)
 err_adc_clk:
 	regmap_update_bits(priv->regmap, MESON_SAR_ADC_REG3,
 			   MESON_SAR_ADC_REG3_ADC_EN, 0);
-	regmap_update_bits(priv->regmap, MESON_SAR_ADC_REG11,
-			   MESON_SAR_ADC_REG11_BANDGAP_EN, 0);
+	meson_sar_adc_set_bandgap(indio_dev, false);
 	clk_disable_unprepare(priv->sana_clk);
 err_sana_clk:
 	clk_disable_unprepare(priv->core_clk);
@@ -765,8 +779,8 @@ static int meson_sar_adc_hw_disable(struct iio_dev *indio_dev)
 
 	regmap_update_bits(priv->regmap, MESON_SAR_ADC_REG3,
 			   MESON_SAR_ADC_REG3_ADC_EN, 0);
-	regmap_update_bits(priv->regmap, MESON_SAR_ADC_REG11,
-			   MESON_SAR_ADC_REG11_BANDGAP_EN, 0);
+
+	meson_sar_adc_set_bandgap(indio_dev, false);
 
 	clk_disable_unprepare(priv->sana_clk);
 	clk_disable_unprepare(priv->core_clk);
@@ -844,30 +858,35 @@ static const struct iio_info meson_sar_adc_iio_info = {
 
 static const struct meson_sar_adc_data meson_sar_adc_meson8_data = {
 	.has_bl30_integration = false,
+	.bandgap_reg = MESON_SAR_ADC_DELTA_10,
 	.resolution = 10,
 	.name = "meson-meson8-saradc",
 };
 
 static const struct meson_sar_adc_data meson_sar_adc_meson8b_data = {
 	.has_bl30_integration = false,
+	.bandgap_reg = MESON_SAR_ADC_DELTA_10,
 	.resolution = 10,
 	.name = "meson-meson8b-saradc",
 };
 
 static const struct meson_sar_adc_data meson_sar_adc_gxbb_data = {
 	.has_bl30_integration = true,
+	.bandgap_reg = MESON_SAR_ADC_REG11,
 	.resolution = 10,
 	.name = "meson-gxbb-saradc",
 };
 
 static const struct meson_sar_adc_data meson_sar_adc_gxl_data = {
 	.has_bl30_integration = true,
+	.bandgap_reg = MESON_SAR_ADC_REG11,
 	.resolution = 12,
 	.name = "meson-gxl-saradc",
 };
 
 static const struct meson_sar_adc_data meson_sar_adc_gxm_data = {
 	.has_bl30_integration = true,
+	.bandgap_reg = MESON_SAR_ADC_REG11,
 	.resolution = 12,
 	.name = "meson-gxm-saradc",
 };