[PATCH-vs-togreg 1/2] iio: ina2xx-adc: update the CALIB. register when RShunt changes

[Marc Titinger]

The user (or an init script) may setup RShunt via sysfs after the
driver was initialized, for instance based on the EEPROM contents
of a modular probe. The calibration register must be set accordingly.

Signed-off-by: Marc Titinger <marc.titinger@xxxxxxxxxxxx>
---
tested with BeagleBone-black and BayLibre-acme.
---
 drivers/iio/adc/ina2xx-adc.c | 36 +++++++++++++++++++++++++-----------
 1 file changed, 25 insertions(+), 11 deletions(-)

diff --git a/drivers/iio/adc/ina2xx-adc.c b/drivers/iio/adc/ina2xx-adc.c
index 65909d5..e5ac120 100644
--- a/drivers/iio/adc/ina2xx-adc.c
+++ b/drivers/iio/adc/ina2xx-adc.c
@@ -350,6 +350,23 @@ static ssize_t ina2xx_allow_async_readout_store(struct device *dev,
 	return len;
 }
 
+/*
+ * Set current LSB to 1mA, shunt is in uOhms
+ * (equation 13 in datasheet). We hardcode a Current_LSB
+ * of 1.0 x10-6. The only remaining parameter is RShunt.
+ * There is no need to expose the CALIBRATION register
+ * to the user for now. But we need to reset this register
+ * if the user updates RShunt after driver init, e.g upon
+ * reading an EEPROM/Probe-type value.
+ */
+static int ina2xx_set_calibration(struct ina2xx_chip_info *chip)
+{
+	u16 regval = DIV_ROUND_CLOSEST(chip->config->calibration_factor,
+				   chip->shunt_resistor);
+
+	return regmap_write(chip->regmap, INA2XX_CALIBRATION, regval);
+}
+
 static int set_shunt_resistor(struct ina2xx_chip_info *chip, unsigned int val)
 {
 	if (val <= 0 || val > chip->config->calibration_factor)
@@ -385,6 +402,11 @@ static ssize_t ina2xx_shunt_resistor_store(struct device *dev,
 	if (ret)
 		return ret;
 
+	/* Update the Calibration register */
+	ret = ina2xx_set_calibration(chip);
+	if (ret)
+		return ret;
+
 	return len;
 }
 
@@ -599,6 +621,8 @@ static const struct iio_info ina2xx_info = {
 	.debugfs_reg_access = ina2xx_debug_reg,
 };
 
+
+
 /* Initialize the configuration and calibration registers. */
 static int ina2xx_init(struct ina2xx_chip_info *chip, unsigned int config)
 {
@@ -609,17 +633,7 @@ static int ina2xx_init(struct ina2xx_chip_info *chip, unsigned int config)
 	if (ret)
 		return ret;
 
-	/*
-	 * Set current LSB to 1mA, shunt is in uOhms
-	 * (equation 13 in datasheet). We hardcode a Current_LSB
-	 * of 1.0 x10-6. The only remaining parameter is RShunt.
-	 * There is no need to expose the CALIBRATION register
-	 * to the user for now.
-	 */
-	regval = DIV_ROUND_CLOSEST(chip->config->calibration_factor,
-				   chip->shunt_resistor);
-
-	return regmap_write(chip->regmap, INA2XX_CALIBRATION, regval);
+	return ina2xx_set_calibration(chip);
 }
 
 static int ina2xx_probe(struct i2c_client *client,
-- 
2.5.0