[PATCH v3 09/14] iio: adc: ad7768: Add VCM regulator support

[Janani Sunil <janani.sunil@analog.com>]

Expose the on-chip common mode voltage output through the regulator
framework. Support the three fixed output levels and the
supply-dependent AVDD1/2 setting.

Keep the ADC runtime active while VCM is enabled and release the runtime
PM reference when the output is disabled.

Signed-off-by: Janani Sunil <janani.sunil@analog.com>
---
 drivers/iio/adc/ad7768.c | 157 ++++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 155 insertions(+), 2 deletions(-)

diff --git a/drivers/iio/adc/ad7768.c b/drivers/iio/adc/ad7768.c
index d332695cc75d..d7151b1fa863 100644
--- a/drivers/iio/adc/ad7768.c
+++ b/drivers/iio/adc/ad7768.c
@@ -22,6 +22,7 @@
 #include <linux/property.h>
 #include <linux/regmap.h>
 #include <linux/regulator/consumer.h>
+#include <linux/regulator/driver.h>
 #include <linux/reset.h>
 #include <linux/spi/spi.h>
 #include <linux/time64.h>
@@ -89,6 +90,8 @@
 #define   AD7768_INTERFACE_CFG_CRC_SELECT	FIELD_PREP(GENMASK(3, 2), 0x01)
 
 /* AD7768_REG_GENERAL_CONFIG */
+#define   AD7768_GEN_CONFIG_VCM_SEL_MSK		GENMASK(1, 0)
+#define   AD7768_GEN_CONFIG_VCM_PD		BIT(4)
 /* AD7768_REG_PRECHARGE_BUF1 and 2*/
 #define   AD7768_PREBUF_POS_EN(ch)	BIT((ch) * 2)
 #define   AD7768_PREBUF_NEG_EN(ch)	BIT(((ch) * 2) + 1)
@@ -167,10 +170,154 @@ struct ad7768_state {
 	u64 ch_convdelay_ps[AD7768_MAX_CHANNEL];
 	enum ad7768_filter_type ch_filter[AD7768_MAX_CHANNEL];
 	struct iio_backend *back;
+	struct regulator_dev *vcm_rdev;
+	unsigned int avdd1_uV;
 
 	__be16 d16 __aligned(IIO_DMA_MINALIGN);
 };
 
+static const unsigned int ad7768_vcm_voltage_table[] = {
+	0, 1650000, 2500000, 2140000,
+};
+
+static int ad7768_vcm_list_voltage(struct regulator_dev *rdev,
+				   unsigned int selector)
+{
+	struct ad7768_state *st = rdev_get_drvdata(rdev);
+
+	if (selector >= ARRAY_SIZE(ad7768_vcm_voltage_table))
+		return -EINVAL;
+
+	if (!selector)
+		return DIV_ROUND_CLOSEST(st->avdd1_uV, 2);
+
+	return ad7768_vcm_voltage_table[selector];
+}
+
+static int ad7768_vcm_enable(struct regulator_dev *rdev)
+{
+	struct ad7768_state *st = rdev_get_drvdata(rdev);
+	int ret;
+
+	ret = pm_runtime_resume_and_get(regmap_get_device(st->regmap));
+	if (ret < 0)
+		return ret;
+
+	ret = regmap_clear_bits(st->regmap, AD7768_REG_GENERAL_CONFIG,
+				AD7768_GEN_CONFIG_VCM_PD);
+	if (ret)
+		pm_runtime_put_autosuspend(regmap_get_device(st->regmap));
+
+	return ret;
+}
+
+static int ad7768_vcm_disable(struct regulator_dev *rdev)
+{
+	struct ad7768_state *st = rdev_get_drvdata(rdev);
+	int ret;
+
+	ret = regmap_set_bits(st->regmap, AD7768_REG_GENERAL_CONFIG,
+			      AD7768_GEN_CONFIG_VCM_PD);
+	if (ret)
+		return ret;
+
+	pm_runtime_put_autosuspend(regmap_get_device(st->regmap));
+
+	return 0;
+}
+
+static int ad7768_vcm_is_enabled(struct regulator_dev *rdev)
+{
+	struct ad7768_state *st = rdev_get_drvdata(rdev);
+	int ret;
+
+	PM_RUNTIME_ACQUIRE_IF_ENABLED_AUTOSUSPEND(regmap_get_device(st->regmap), pm);
+	ret = PM_RUNTIME_ACQUIRE_ERR(&pm);
+	if (ret)
+		return ret;
+
+	ret = regmap_test_bits(st->regmap, AD7768_REG_GENERAL_CONFIG,
+			       AD7768_GEN_CONFIG_VCM_PD);
+	if (ret < 0)
+		return ret;
+
+	return !ret;
+}
+
+static int ad7768_vcm_set_voltage_sel(struct regulator_dev *rdev,
+				      unsigned int selector)
+{
+	struct ad7768_state *st = rdev_get_drvdata(rdev);
+	int ret;
+
+	PM_RUNTIME_ACQUIRE_IF_ENABLED_AUTOSUSPEND(regmap_get_device(st->regmap), pm);
+	ret = PM_RUNTIME_ACQUIRE_ERR(&pm);
+	if (ret)
+		return ret;
+
+	return regmap_update_bits(st->regmap, AD7768_REG_GENERAL_CONFIG,
+				  AD7768_GEN_CONFIG_VCM_SEL_MSK, selector);
+}
+
+static int ad7768_vcm_get_voltage_sel(struct regulator_dev *rdev)
+{
+	struct ad7768_state *st = rdev_get_drvdata(rdev);
+	unsigned int val;
+	int ret;
+
+	PM_RUNTIME_ACQUIRE_IF_ENABLED_AUTOSUSPEND(regmap_get_device(st->regmap), pm);
+	ret = PM_RUNTIME_ACQUIRE_ERR(&pm);
+	if (ret)
+		return ret;
+
+	ret = regmap_read(st->regmap, AD7768_REG_GENERAL_CONFIG, &val);
+	if (ret)
+		return ret;
+
+	return FIELD_GET(AD7768_GEN_CONFIG_VCM_SEL_MSK, val);
+}
+
+static const struct regulator_ops ad7768_vcm_ops = {
+	.enable = ad7768_vcm_enable,
+	.disable = ad7768_vcm_disable,
+	.is_enabled = ad7768_vcm_is_enabled,
+	.list_voltage = ad7768_vcm_list_voltage,
+	.set_voltage_sel = ad7768_vcm_set_voltage_sel,
+	.get_voltage_sel = ad7768_vcm_get_voltage_sel,
+};
+
+static const struct regulator_desc ad7768_vcm_desc = {
+	.name = "vcm",
+	.of_match = of_match_ptr("vcm-output"),
+	.regulators_node = "regulators",
+	.n_voltages = ARRAY_SIZE(ad7768_vcm_voltage_table),
+	.ops = &ad7768_vcm_ops,
+	.type = REGULATOR_VOLTAGE,
+	.owner = THIS_MODULE,
+};
+
+static int ad7768_register_vcm_regulator(struct device *dev,
+					 struct ad7768_state *st)
+{
+	struct regulator_config config = {
+		.dev = dev,
+		.driver_data = st,
+	};
+	int ret;
+
+	/*
+	 * Start with VCM disabled so each enabled state is paired with the
+	 * runtime PM reference acquired by ad7768_vcm_enable().
+	 */
+	ret = regmap_set_bits(st->regmap, AD7768_REG_GENERAL_CONFIG,
+			      AD7768_GEN_CONFIG_VCM_PD);
+	if (ret)
+		return ret;
+
+	st->vcm_rdev = devm_regulator_register(dev, &ad7768_vcm_desc, &config);
+	return PTR_ERR_OR_ZERO(st->vcm_rdev);
+}
+
 static const int ad7768_dec_rate[MAX_FREQ_PER_MODE] = {
 	32, 64, 128, 256, 512, 1024,
 };
@@ -1354,10 +1501,12 @@ static int ad7768_probe(struct spi_device *spi)
 
 	st->chip_info = spi_get_device_match_data(spi);
 
-	ret = devm_regulator_get_enable(dev, "avdd1");
-	if (ret)
+	ret = devm_regulator_get_enable_read_voltage(dev, "avdd1");
+	if (ret < 0)
 		return dev_err_probe(dev, ret, "Failed to enable AVDD1 supply\n");
 
+	st->avdd1_uV = ret;
+
 	ret = devm_regulator_bulk_get_enable(dev,
 					     ARRAY_SIZE(ad7768_supply_names),
 					     ad7768_supply_names);
@@ -1430,6 +1579,10 @@ static int ad7768_probe(struct spi_device *spi)
 	if (ret)
 		return ret;
 
+	ret = ad7768_register_vcm_regulator(dev, st);
+	if (ret)
+		return dev_err_probe(dev, ret, "Failed to register VCM regulator\n");
+
 	indio_dev->setup_ops = &ad7768_buffer_ops;
 
 	ret = devm_iio_device_register(dev, indio_dev);

-- 
2.43.0