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Subject[PATCH V4 3/4] staging: iio: adc: ad7192: Add system calibration support
Date
This patch will add a system calibration attribute for each channel. Using
this option the user will have the ability to calibrate each channel for
zero scale and full scale. It uses the iio_chan_spec_ext_info and IIO_ENUM
to implement the functionality.

Signed-off-by: Mircea Caprioru <mircea.caprioru@analog.com>
---
Changelog V2:
- no changes here

Changelog V3:
- no changes here

Changelog V4:
- add an attribute to start the system calibration
- the mode attribute does not trigger the calibration
- added ABI documentation

.../ABI/testing/sysfs-bus-iio-adc-ad7192 | 24 ++++++
drivers/staging/iio/adc/ad7192.c | 79 ++++++++++++++++++-
2 files changed, 102 insertions(+), 1 deletion(-)

diff --git a/Documentation/ABI/testing/sysfs-bus-iio-adc-ad7192 b/Documentation/ABI/testing/sysfs-bus-iio-adc-ad7192
index 74a2873045bf..7627d3be08f5 100644
--- a/Documentation/ABI/testing/sysfs-bus-iio-adc-ad7192
+++ b/Documentation/ABI/testing/sysfs-bus-iio-adc-ad7192
@@ -13,3 +13,27 @@ Description:
need to minimize the system current consumption.
Reading gives the state of the bridge switch.
Writing '1' enables the bridge switch.
+
+What: /sys/bus/iio/devices/iio:deviceX/in_voltagex_sys_calibration
+KernelVersion:
+Contact: linux-iio@vger.kernel.org
+Description:
+ Initiates the system calibration procedure. This is done on a
+ single channel at a time. Write '1' to start the calibration.
+
+What: /sys/bus/iio/devices/iio:deviceX/in_voltagex_sys_calibration_mode_available
+KernelVersion:
+Contact: linux-iio@vger.kernel.org
+Description:
+ Reading returns a list with the possible calibration modes.
+ There are two available options:
+ "zero_scale" - calibrate to zero scale
+ "full_scale" - calibrate to full scale
+
+What: /sys/bus/iio/devices/iio:deviceX/in_voltagex_sys_calibration_mode
+KernelVersion:
+Contact: linux-iio@vger.kernel.org
+Description:
+ Sets up the calibration mode used in the system calibration
+ procedure. Reading returns the current calibration mode.
+ Writing sets the system calibration mode.
diff --git a/drivers/staging/iio/adc/ad7192.c b/drivers/staging/iio/adc/ad7192.c
index d58ce08f3693..c5106d98c9b3 100644
--- a/drivers/staging/iio/adc/ad7192.c
+++ b/drivers/staging/iio/adc/ad7192.c
@@ -155,6 +155,11 @@
* The DOUT/RDY output must also be wired to an interrupt capable GPIO.
*/

+enum {
+ AD7192_SYSCALIB_ZERO_SCALE,
+ AD7192_SYSCALIB_FULL_SCALE,
+};
+
struct ad7192_state {
struct regulator *avdd;
struct regulator *dvdd;
@@ -169,10 +174,80 @@ struct ad7192_state {
u8 devid;
u8 clock_sel;
struct mutex lock; /* protect sensor state */
+ u8 syscalib_mode[8];

struct ad_sigma_delta sd;
};

+static const char * const ad7192_syscalib_modes[] = {
+ [AD7192_SYSCALIB_ZERO_SCALE] = "zero_scale",
+ [AD7192_SYSCALIB_FULL_SCALE] = "full_scale",
+};
+
+static int ad7192_set_syscalib_mode(struct iio_dev *indio_dev,
+ const struct iio_chan_spec *chan,
+ unsigned int mode)
+{
+ struct ad7192_state *st = iio_priv(indio_dev);
+
+ st->syscalib_mode[chan->channel] = mode;
+
+ return 0;
+}
+
+static int ad7192_get_syscalib_mode(struct iio_dev *indio_dev,
+ const struct iio_chan_spec *chan)
+{
+ struct ad7192_state *st = iio_priv(indio_dev);
+
+ return st->syscalib_mode[chan->channel];
+}
+
+static ssize_t ad7192_write_syscalib(struct iio_dev *indio_dev,
+ uintptr_t private,
+ const struct iio_chan_spec *chan,
+ const char *buf, size_t len)
+{
+ struct ad7192_state *st = iio_priv(indio_dev);
+ bool sys_calib;
+ int ret, temp;
+
+ ret = strtobool(buf, &sys_calib);
+ if (ret)
+ return ret;
+
+ temp = st->syscalib_mode[chan->channel];
+ if (sys_calib) {
+ if (temp == AD7192_SYSCALIB_ZERO_SCALE)
+ ret = ad_sd_calibrate(&st->sd, AD7192_MODE_CAL_SYS_ZERO,
+ chan->address);
+ else
+ ret = ad_sd_calibrate(&st->sd, AD7192_MODE_CAL_SYS_FULL,
+ chan->address);
+ }
+
+ return ret ? ret : len;
+}
+
+static const struct iio_enum ad7192_syscalib_mode_enum = {
+ .items = ad7192_syscalib_modes,
+ .num_items = ARRAY_SIZE(ad7192_syscalib_modes),
+ .set = ad7192_set_syscalib_mode,
+ .get = ad7192_get_syscalib_mode
+};
+
+static const struct iio_chan_spec_ext_info ad7192_calibsys_ext_info[] = {
+ {
+ .name = "sys_calibration",
+ .write = ad7192_write_syscalib,
+ .shared = IIO_SEPARATE,
+ },
+ IIO_ENUM("sys_calibration_mode", IIO_SEPARATE,
+ &ad7192_syscalib_mode_enum),
+ IIO_ENUM_AVAILABLE("sys_calibration_mode", &ad7192_syscalib_mode_enum),
+ {}
+};
+
static struct ad7192_state *ad_sigma_delta_to_ad7192(struct ad_sigma_delta *sd)
{
return container_of(sd, struct ad7192_state, sd);
@@ -769,9 +844,11 @@ static int ad7192_channels_config(struct iio_dev *indio_dev)
*chan = channels[i];
chan->info_mask_shared_by_all |=
BIT(IIO_CHAN_INFO_LOW_PASS_FILTER_3DB_FREQUENCY);
- if (chan->type != IIO_TEMP)
+ if (chan->type != IIO_TEMP) {
chan->info_mask_shared_by_type_available |=
BIT(IIO_CHAN_INFO_SCALE);
+ chan->ext_info = ad7192_calibsys_ext_info;
+ }
chan++;
}

--
2.17.1
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