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iio: adc: ad4695: implement calibration support

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The AD4695 has a calibration feature that allows the user to compensate
for variations in the analog front end. This implements this feature in
the driver using the standard `calibgain` and `calibbias` attributes.

Signed-off-by: David Lechner <dlechner@baylibre.com>
Link: https://patch.msgid.link/20240820-ad4695-gain-offset-v1-2-c8f6e3b47551@baylibre.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
This commit is contained in:
David Lechner 2024-08-20 10:58:36 -05:00 committed by Jonathan Cameron
parent 2ba49fc41b
commit 7763e40f35
1 changed files with 156 additions and 2 deletions
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158
drivers/iio/adc/ad4695.c
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@ -23,6 +23,7 @@
#include <linux/iio/iio.h>
#include <linux/iio/triggered_buffer.h>
#include <linux/iio/trigger_consumer.h>
#include <linux/minmax.h>
#include <linux/property.h>
#include <linux/regmap.h>
#include <linux/regulator/consumer.h>
@ -225,7 +226,11 @@ static const struct iio_chan_spec ad4695_channel_template = {
.indexed = 1,
.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
BIT(IIO_CHAN_INFO_SCALE) |
BIT(IIO_CHAN_INFO_OFFSET),
BIT(IIO_CHAN_INFO_OFFSET) |
BIT(IIO_CHAN_INFO_CALIBSCALE) |
BIT(IIO_CHAN_INFO_CALIBBIAS),
.info_mask_separate_available = BIT(IIO_CHAN_INFO_CALIBSCALE) |
BIT(IIO_CHAN_INFO_CALIBBIAS),
.scan_type = {
.sign = 'u',
.realbits = 16,
@ -619,7 +624,8 @@ static int ad4695_read_raw(struct iio_dev *indio_dev,
struct ad4695_state *st = iio_priv(indio_dev);
struct ad4695_channel_config *cfg = &st->channels_cfg[chan->scan_index];
u8 realbits = chan->scan_type.realbits;
int ret;
unsigned int reg_val;
int ret, tmp;
switch (mask) {
case IIO_CHAN_INFO_RAW:
@ -670,6 +676,152 @@ static int ad4695_read_raw(struct iio_dev *indio_dev,
default:
return -EINVAL;
}
case IIO_CHAN_INFO_CALIBSCALE:
switch (chan->type) {
case IIO_VOLTAGE:
iio_device_claim_direct_scoped(return -EBUSY, indio_dev) {
ret = regmap_read(st->regmap16,
AD4695_REG_GAIN_IN(chan->scan_index),
&reg_val);
if (ret)
return ret;
*val = reg_val;
*val2 = 15;
return IIO_VAL_FRACTIONAL_LOG2;
}
unreachable();
default:
return -EINVAL;
}
case IIO_CHAN_INFO_CALIBBIAS:
switch (chan->type) {
case IIO_VOLTAGE:
iio_device_claim_direct_scoped(return -EBUSY, indio_dev) {
ret = regmap_read(st->regmap16,
AD4695_REG_OFFSET_IN(chan->scan_index),
&reg_val);
if (ret)
return ret;
tmp = sign_extend32(reg_val, 15);
*val = tmp / 4;
*val2 = abs(tmp) % 4 * MICRO / 4;
if (tmp < 0 && *val2) {
*val *= -1;
*val2 *= -1;
}
return IIO_VAL_INT_PLUS_MICRO;
}
unreachable();
default:
return -EINVAL;
}
default:
return -EINVAL;
}
}
static int ad4695_write_raw(struct iio_dev *indio_dev,
struct iio_chan_spec const *chan,
int val, int val2, long mask)
{
struct ad4695_state *st = iio_priv(indio_dev);
unsigned int reg_val;
iio_device_claim_direct_scoped(return -EBUSY, indio_dev) {
switch (mask) {
case IIO_CHAN_INFO_CALIBSCALE:
switch (chan->type) {
case IIO_VOLTAGE:
if (val < 0 || val2 < 0)
reg_val = 0;
else if (val > 1)
reg_val = U16_MAX;
else
reg_val = (val * (1 << 16) +
mul_u64_u32_div(val2, 1 << 16,
MICRO)) / 2;
return regmap_write(st->regmap16,
AD4695_REG_GAIN_IN(chan->scan_index),
reg_val);
default:
return -EINVAL;
}
case IIO_CHAN_INFO_CALIBBIAS:
switch (chan->type) {
case IIO_VOLTAGE:
if (val2 >= 0 && val > S16_MAX / 4)
reg_val = S16_MAX;
else if ((val2 < 0 ? -val : val) < S16_MIN / 4)
reg_val = S16_MIN;
else if (val2 < 0)
reg_val = clamp_t(int,
-(val * 4 + -val2 * 4 / MICRO),
S16_MIN, S16_MAX);
else if (val < 0)
reg_val = clamp_t(int,
val * 4 - val2 * 4 / MICRO,
S16_MIN, S16_MAX);
else
reg_val = clamp_t(int,
val * 4 + val2 * 4 / MICRO,
S16_MIN, S16_MAX);
return regmap_write(st->regmap16,
AD4695_REG_OFFSET_IN(chan->scan_index),
reg_val);
default:
return -EINVAL;
}
default:
return -EINVAL;
}
}
unreachable();
}
static int ad4695_read_avail(struct iio_dev *indio_dev,
struct iio_chan_spec const *chan,
const int **vals, int *type, int *length,
long mask)
{
static const int ad4695_calibscale_available[6] = {
/* Range of 0 (inclusive) to 2 (exclusive) */
0, 15, 1, 15, U16_MAX, 15
};
static const int ad4695_calibbias_available[6] = {
/*
* Datasheet says FSR/8 which translates to signed/4. The step
* depends on oversampling ratio which is always 1 for now.
*/
S16_MIN / 4, 0, 0, MICRO / 4, S16_MAX / 4, S16_MAX % 4 * MICRO / 4
};
switch (mask) {
case IIO_CHAN_INFO_CALIBSCALE:
switch (chan->type) {
case IIO_VOLTAGE:
*vals = ad4695_calibscale_available;
*type = IIO_VAL_FRACTIONAL_LOG2;
return IIO_AVAIL_RANGE;
default:
return -EINVAL;
}
case IIO_CHAN_INFO_CALIBBIAS:
switch (chan->type) {
case IIO_VOLTAGE:
*vals = ad4695_calibbias_available;
*type = IIO_VAL_INT_PLUS_MICRO;
return IIO_AVAIL_RANGE;
default:
return -EINVAL;
}
default:
return -EINVAL;
}
@ -705,6 +857,8 @@ static int ad4695_debugfs_reg_access(struct iio_dev *indio_dev,
static const struct iio_info ad4695_info = {
.read_raw = &ad4695_read_raw,
.write_raw = &ad4695_write_raw,
.read_avail = &ad4695_read_avail,
.debugfs_reg_access = &ad4695_debugfs_reg_access,
};