Re: [PATCH-vs-togreg v2 1/2] iio: ina2xx-adc: update the CALIB. register when RShunt changes

[Marc Titinger]

On 20/03/2016 12:24, Jonathan Cameron wrote:

On 14/03/16 10:20, Marc Titinger wrote:

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.titin...@baylibre.com>
---
  v2 of http://www.spinics.net/lists/linux-iio/msg23402.html:

        - remove unnecessary line insertions
        - cleanup leftover unused variable (build warning)
        - patch 2/2 is unchanged (see v1)

Err, can't find it for some reason.

sorry, it's here http://www.spinics.net/lists/linux-iio/msg23401.html
or here: pwclient get 8565821

BR,
Marc.

Anyhow, applied this one to the togreg branch of iio.git - pushed
out as testing for the autobuilders to play with it.

Thanks,

Jonathan

---
  drivers/iio/adc/ina2xx-adc.c | 39 ++++++++++++++++++++++++---------------
  1 file changed, 24 insertions(+), 15 deletions(-)

diff --git a/drivers/iio/adc/ina2xx-adc.c b/drivers/iio/adc/ina2xx-adc.c
index 65909d5..4e56fe3 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;
  }

@@ -602,24 +624,11 @@ static const struct iio_info ina2xx_info = {
  /* Initialize the configuration and calibration registers. */
  static int ina2xx_init(struct ina2xx_chip_info *chip, unsigned int config)
  {
-       u16 regval;
-       int ret;
-
-       ret = regmap_write(chip->regmap, INA2XX_CONFIG, config);
+       int ret = regmap_write(chip->regmap, INA2XX_CONFIG, 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,