[PATCH v3 09/14] iio: adc: ad7768: Add VCM regulator support
From: Janani Sunil
Date: Thu Aug 13 2026 - 10:04:15 EST
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@xxxxxxxxxx>
---
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