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iio: dac: ad5686: add gain control support

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Most of the supported devices rely on a GAIN pin to control a 2x
multiplier applied to the output voltage. Other devices, e.g. the
single-channel ones, provides a gain control through a bit field in
the control register. Some designs might have the GAIN pin hardwired
to VDD/VLOGIC or GND, which would have no "gain-gpios" device property,
being able to set "adi,range-double" if it is hardwired to VDD. The
vref_mv field is moved down in the struct ad5686_state, so that the
overall size increase is reduced.

Reviewed-by: David Lechner <dlechner@baylibre.com>
Signed-off-by: Rodrigo Alencar <rodrigo.alencar@analog.com>
Signed-off-by: Jonathan Cameron <jonathan.cameron@oss.qualcomm.com>
This commit is contained in:
Rodrigo Alencar 2026-07-16 13:14:24 +01:00 committed by Jonathan Cameron
parent a3c37fa97b
commit 23f66b58b1
2 changed files with 125 additions and 7 deletions
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120
drivers/iio/dac/ad5686.c
View File

@ -15,10 +15,13 @@
#include <linux/export.h>
#include <linux/gpio/consumer.h>
#include <linux/kstrtox.h>
#include <linux/math64.h>
#include <linux/module.h>
#include <linux/property.h>
#include <linux/regulator/consumer.h>
#include <linux/reset.h>
#include <linux/sysfs.h>
#include <linux/units.h>
#include <linux/wordpart.h>
#include <linux/iio/buffer.h>
@ -41,7 +44,8 @@ static int ad5310_control_sync(struct ad5686_state *st)
return ad5686_write(st, AD5686_CMD_CONTROL_REG, 0,
FIELD_PREP(AD5310_DATA_PD_MSK, pd_val & AD5686_PD_MSK) |
FIELD_PREP(AD5310_DATA_REF_MSK, st->use_internal_vref ? 0 : 1));
FIELD_PREP(AD5310_DATA_REF_MSK, st->use_internal_vref ? 0 : 1) |
FIELD_PREP(AD5310_DATA_GAIN_MSK, st->double_scale ? 1 : 0));
}
static int ad5683_control_sync(struct ad5686_state *st)
@ -50,7 +54,8 @@ static int ad5683_control_sync(struct ad5686_state *st)
return ad5686_write(st, AD5686_CMD_CONTROL_REG, 0,
FIELD_PREP(AD5683_DATA_PD_MSK, pd_val & AD5686_PD_MSK) |
FIELD_PREP(AD5683_DATA_REF_MSK, st->use_internal_vref ? 0 : 1));
FIELD_PREP(AD5683_DATA_REF_MSK, st->use_internal_vref ? 0 : 1) |
FIELD_PREP(AD5683_DATA_GAIN_MSK, st->double_scale ? 1 : 0));
}
static inline unsigned int ad5686_pd_mask_shift(const struct iio_chan_spec *chan)
@ -193,9 +198,14 @@ static int ad5686_read_raw(struct iio_dev *indio_dev,
GENMASK(chan->scan_type.realbits - 1, 0);
return IIO_VAL_INT;
case IIO_CHAN_INFO_SCALE:
*val = st->vref_mv;
*val2 = chan->scan_type.realbits;
return IIO_VAL_FRACTIONAL_LOG2;
if (st->double_scale) {
*val = st->scale_avail[2];
*val2 = st->scale_avail[3];
} else {
*val = st->scale_avail[0];
*val2 = st->scale_avail[1];
}
return IIO_VAL_INT_PLUS_NANO;
}
return -EINVAL;
}
@ -207,6 +217,8 @@ static int ad5686_write_raw(struct iio_dev *indio_dev,
long mask)
{
struct ad5686_state *st = iio_priv(indio_dev);
bool double_scale;
int ret;
guard(mutex)(&st->lock);
@ -217,6 +229,82 @@ static int ad5686_write_raw(struct iio_dev *indio_dev,
return ad5686_write(st, AD5686_CMD_WRITE_INPUT_N_UPDATE_N,
chan->address, val << chan->scan_type.shift);
case IIO_CHAN_INFO_SCALE:
if (val == st->scale_avail[0] && val2 == st->scale_avail[1])
double_scale = false;
else if (val == st->scale_avail[2] && val2 == st->scale_avail[3])
double_scale = true;
else
return -EINVAL;
if (st->double_scale == double_scale)
return 0; /* no change */
if (st->chip_info->regmap_type == AD5686_REGMAP && !st->gain_gpio)
return -EINVAL; /* GAIN pin is board-strapped */
st->double_scale = double_scale;
switch (st->chip_info->regmap_type) {
case AD5310_REGMAP:
ret = ad5310_control_sync(st);
break;
case AD5683_REGMAP:
ret = ad5683_control_sync(st);
break;
case AD5686_REGMAP:
ret = gpiod_set_value_cansleep(st->gain_gpio,
st->double_scale ? 1 : 0);
break;
default:
ret = -EINVAL;
}
if (ret)
st->double_scale = !double_scale; /* revert on failure */
return ret;
default:
return -EINVAL;
}
}
static int ad5686_write_raw_get_fmt(struct iio_dev *indio_dev,
struct iio_chan_spec const *chan,
long mask)
{
switch (mask) {
case IIO_CHAN_INFO_RAW:
return IIO_VAL_INT;
case IIO_CHAN_INFO_SCALE:
return IIO_VAL_INT_PLUS_NANO;
default:
return -EINVAL;
}
}
static int ad5686_read_avail(struct iio_dev *indio_dev,
struct iio_chan_spec const *chan,
const int **vals, int *type, int *length,
long mask)
{
struct ad5686_state *st = iio_priv(indio_dev);
switch (mask) {
case IIO_CHAN_INFO_SCALE:
*type = IIO_VAL_INT_PLUS_NANO;
if (st->chip_info->regmap_type == AD5686_REGMAP && !st->gain_gpio) {
/*
* GAIN pin is board-strapped, so only the current
* scale is available.
*/
*vals = st->double_scale ? &st->scale_avail[2] :
&st->scale_avail[0];
*length = 2;
return IIO_AVAIL_LIST;
}
*vals = st->scale_avail;
*length = ARRAY_SIZE(st->scale_avail);
return IIO_AVAIL_LIST;
default:
return -EINVAL;
}
@ -225,6 +313,8 @@ static int ad5686_write_raw(struct iio_dev *indio_dev,
static const struct iio_info ad5686_info = {
.read_raw = ad5686_read_raw,
.write_raw = ad5686_write_raw,
.write_raw_get_fmt = ad5686_write_raw_get_fmt,
.read_avail = ad5686_read_avail,
};
static const struct iio_chan_spec_ext_info ad5686_ext_info[] = {
@ -246,6 +336,7 @@ static const struct iio_chan_spec_ext_info ad5686_ext_info[] = {
.channel = chan, \
.info_mask_separate = BIT(IIO_CHAN_INFO_RAW), \
.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),\
.info_mask_shared_by_type_available = BIT(IIO_CHAN_INFO_SCALE),\
.address = addr, \
.scan_index = chan, \
.scan_type = { \
@ -472,6 +563,15 @@ const struct ad5686_chip_info ad5679r_chip_info = {
};
EXPORT_SYMBOL_NS_GPL(ad5679r_chip_info, "IIO_AD5686");
static void ad5686_init_scale_avail(struct ad5686_state *st)
{
int realbits = st->chip_info->channels[0].scan_type.realbits;
s64 tmp = 2ULL * st->vref_mv * NANO >> realbits;
st->scale_avail[2] = div_s64_rem(tmp, NANO, &st->scale_avail[3]);
st->scale_avail[0] = div_s64_rem(tmp >> 1, NANO, &st->scale_avail[1]);
}
static void do_ad5686_trigger_handler(struct iio_dev *indio_dev)
{
struct ad5686_state *st = iio_priv(indio_dev);
@ -584,6 +684,16 @@ int ad5686_probe(struct device *dev,
return dev_err_probe(dev, PTR_ERR(st->ldac_gpio),
"Failed to get LDAC GPIO\n");
st->double_scale = device_property_read_bool(dev, "adi,range-double");
st->gain_gpio = devm_gpiod_get_optional(dev, "gain",
st->double_scale ? GPIOD_OUT_HIGH :
GPIOD_OUT_LOW);
if (IS_ERR(st->gain_gpio))
return dev_err_probe(dev, PTR_ERR(st->gain_gpio),
"Failed to get GAIN GPIO\n");
ad5686_init_scale_avail(st);
/* Initialize masks to all ones */
st->pwr_down_mask = ~0;
st->pwr_down_mode = ~0;

12
drivers/iio/dac/ad5686.h
View File

@ -41,9 +41,11 @@
#define AD5686_CMD_CONTROL_REG 0x4
#define AD5686_CMD_READBACK_ENABLE_V2 0x5
#define AD5310_DATA_GAIN_MSK BIT(7)
#define AD5310_DATA_REF_MSK BIT(8)
#define AD5310_DATA_PD_MSK GENMASK(10, 9)
#define AD5683_DATA_GAIN_MSK BIT(11) /* DB15 */
#define AD5683_DATA_REF_MSK BIT(12) /* DB16 */
#define AD5683_DATA_PD_MSK GENMASK(14, 13) /* DB18:DB17 */
@ -127,9 +129,12 @@ extern const struct ad5686_chip_info ad5679r_chip_info;
* @chip_info: chip model specific constants, available modes etc
* @ops: bus specific operations
* @ldac_gpio: LDAC pin GPIO descriptor
* @vref_mv: actual reference voltage used
* @gain_gpio: GAIN pin GPIO descriptor
* @pwr_down_mask: power down mask
* @pwr_down_mode: current power down mode
* @scale_avail: pre-calculated available scale values
* @vref_mv: actual reference voltage used
* @double_scale: flag to indicate the gain multiplier is applied
* @use_internal_vref: set to true if the internal reference voltage is used
* @lock: lock to protect access to state fields, which includes
* the data buffer during regmap ops
@ -141,9 +146,12 @@ struct ad5686_state {
const struct ad5686_chip_info *chip_info;
const struct ad5686_bus_ops *ops;
struct gpio_desc *ldac_gpio;
unsigned short vref_mv;
struct gpio_desc *gain_gpio;
unsigned int pwr_down_mask;
unsigned int pwr_down_mode;
int scale_avail[4];
unsigned short vref_mv;
bool double_scale;
bool use_internal_vref;
struct mutex lock;
void *bus_data;