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Message-Id: <20240820-ad4695-gain-offset-v1-2-c8f6e3b47551@baylibre.com>
Date: Tue, 20 Aug 2024 10:58:36 -0500
From: David Lechner <dlechner@...libre.com>
To: Jonathan Cameron <jic23@...nel.org>
Cc: Michael Hennerich <Michael.Hennerich@...log.com>,
Nuno Sá <nuno.sa@...log.com>,
Jonathan Corbet <corbet@....net>, linux-iio@...r.kernel.org,
linux-kernel@...r.kernel.org, linux-doc@...r.kernel.org,
David Lechner <dlechner@...libre.com>
Subject: [PATCH 2/4] iio: adc: ad4695: implement calibration support
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@...libre.com>
---
drivers/iio/adc/ad4695.c | 159 ++++++++++++++++++++++++++++++++++++++++++++++-
1 file changed, 157 insertions(+), 2 deletions(-)
diff --git a/drivers/iio/adc/ad4695.c b/drivers/iio/adc/ad4695.c
index 63d816ad2d1f..181c4146188c 100644
--- a/drivers/iio/adc/ad4695.c
+++ b/drivers/iio/adc/ad4695.c
@@ -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 +676,153 @@ 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),
+ ®_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),
+ ®_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;
+ int ret;
+
+ 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 +858,8 @@ 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,
};
--
2.43.0
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