iio: ina2xx: re-instate a sysfs show/store for the shunt resistor value

Different probe modules use different resistor values. The front-end
application may read a probe ID (from eeprom) and set the shunt value
accordingly.

Signed-off-by: Marc Titinger <mtitinger@baylibre.com>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

diff --git a/drivers/iio/adc/ina2xx-adc.c b/drivers/iio/adc/ina2xx-adc.c
index ff31f5b49a4164e49baf381c8a81dba8dcfb6866..dd4ff08d7b62e8ce7ef18297ec552b37dfe230b6 100644 (file)
--- a/drivers/iio/adc/ina2xx-adc.c
+++ b/drivers/iio/adc/ina2xx-adc.c
@@ -111,7 +111,7 @@ struct ina2xx_chip_info {
        struct task_struct *task;
        const struct ina2xx_config *config;
        struct mutex state_lock;
-       long rshunt;
+       unsigned int shunt_resistor;
        int avg;
        s64 prev_ns;    /* track buffer capture time, check for underruns*/
        int int_time_vbus; /* Bus voltage integration time uS */
@@ -349,6 +349,42 @@ static ssize_t ina2xx_allow_async_readout_store(struct device *dev,
        return len;
 }
 
+static int set_shunt_resistor(struct ina2xx_chip_info *chip, unsigned int val)
+{
+       if (val <= 0 || val > chip->config->calibration_factor)
+               return -EINVAL;
+
+       chip->shunt_resistor = val;
+       return 0;
+}
+
+static ssize_t ina2xx_shunt_resistor_show(struct device *dev,
+                                         struct device_attribute *attr,
+                                         char *buf)
+{
+       struct ina2xx_chip_info *chip = iio_priv(dev_to_iio_dev(dev));
+
+       return sprintf(buf, "%d\n", chip->shunt_resistor);
+}
+
+static ssize_t ina2xx_shunt_resistor_store(struct device *dev,
+                                          struct device_attribute *attr,
+                                          const char *buf, size_t len)
+{
+       struct ina2xx_chip_info *chip = iio_priv(dev_to_iio_dev(dev));
+       unsigned long val;
+       int ret;
+
+       ret = kstrtoul((const char *) buf, 10, &val);
+       if (ret)
+               return ret;
+
+       ret = set_shunt_resistor(chip, val);
+       if (ret)
+               return ret;
+
+       return len;
+}
 
 #define INA2XX_CHAN(_type, _index, _address) { \
        .type = (_type), \
@@ -545,9 +581,14 @@ static IIO_DEVICE_ATTR(in_allow_async_readout, S_IRUGO | S_IWUSR,
                       ina2xx_allow_async_readout_show,
                       ina2xx_allow_async_readout_store, 0);
 
+static IIO_DEVICE_ATTR(in_shunt_resistor, S_IRUGO | S_IWUSR,
+                      ina2xx_shunt_resistor_show,
+                      ina2xx_shunt_resistor_store, 0);
+
 static struct attribute *ina2xx_attributes[] = {
        &iio_dev_attr_in_allow_async_readout.dev_attr.attr,
        &iio_const_attr_integration_time_available.dev_attr.attr,
+       &iio_dev_attr_in_shunt_resistor.dev_attr.attr,
        NULL,
 };
 
@@ -579,7 +620,7 @@ static int ina2xx_init(struct ina2xx_chip_info *chip, unsigned int config)
         * to the user for now.
         */
        regval = DIV_ROUND_CLOSEST(chip->config->calibration_factor,
-                           chip->rshunt);
+                           chip->shunt_resistor);
 
        return regmap_write(chip->regmap, INA2XX_CALIBRATION, regval);
 }
@@ -612,10 +653,9 @@ static int ina2xx_probe(struct i2c_client *client,
                        val = INA2XX_RSHUNT_DEFAULT;
        }
 
-       if (val <= 0 || val > chip->config->calibration_factor)
-               return -ENODEV;
-
-       chip->rshunt = val;
+       ret = set_shunt_resistor(chip, val);
+       if (ret)
+               return ret;
 
        mutex_init(&chip->state_lock);