The shunt resistance can only be set via platform_data or device tree. This
isn't suitable for devices in which the shunt resistance can change/isn't
known at boot-time.
Add a sysfs attribute that allows to read and set the shunt resistance.
Signed-off-by: Bartosz Golaszewski <bgolaszewski@xxxxxxxxxxxx>
---
Documentation/hwmon/ina2xx | 5 +++--
drivers/hwmon/ina2xx.c | 48 ++++++++++++++++++++++++++++++++++++++++++++--
2 files changed, 49 insertions(+), 4 deletions(-)
diff --git a/Documentation/hwmon/ina2xx b/Documentation/hwmon/ina2xx
index 4223c2d..320dd69 100644
--- a/Documentation/hwmon/ina2xx
+++ b/Documentation/hwmon/ina2xx
@@ -44,6 +44,7 @@ The INA226 monitors both a shunt voltage drop and bus supply voltage.
The INA230 is a high or low side current shunt and power monitor with an I2C
interface. The INA230 monitors both a shunt voltage drop and bus supply voltage.
-The shunt value in micro-ohms can be set via platform data or device tree.
-Please refer to the Documentation/devicetree/bindings/i2c/ina2xx.txt for bindings
+The shunt value in micro-ohms can be set via platform data or device tree at
+compile-time or via the shunt_resistor attribute in sysfs at run-time. Please
+refer to the Documentation/devicetree/bindings/i2c/ina2xx.txt for bindings
if the device tree is used.
diff --git a/drivers/hwmon/ina2xx.c b/drivers/hwmon/ina2xx.c
index 12f0e12..c7358e8 100644
--- a/drivers/hwmon/ina2xx.c
+++ b/drivers/hwmon/ina2xx.c
@@ -115,6 +115,12 @@ static const struct ina2xx_config ina2xx_config[] = {
},
};
+static int ina2xx_calibrate(struct ina2xx_data *data)
+{
+ return i2c_smbus_write_word_swapped(data->client, INA2XX_CALIBRATION,
+ data->config->calibration_factor / data->rshunt);
+}
+
/*
* Initialize the configuration and calibration registers.
*/
@@ -133,8 +139,7 @@ static int ina2xx_init(struct ina2xx_data *data)
* Set current LSB to 1mA, shunt is in uOhms
* (equation 13 in datasheet).
*/
- return i2c_smbus_write_word_swapped(client, INA2XX_CALIBRATION,
- data->config->calibration_factor / data->rshunt);
+ return ina2xx_calibrate(data);
}
static struct ina2xx_data *ina2xx_update_device(struct device *dev)
@@ -217,6 +222,9 @@ static int ina2xx_get_value(struct ina2xx_data *data, u8 reg)
/* signed register, LSB=1mA (selected), in mA */
val = (s16)data->regs[reg];
break;
+ case INA2XX_CALIBRATION:
+ val = data->config->calibration_factor / data->regs[reg];
+ break;
default:
/* programmer goofed */
WARN_ON_ONCE(1);
@@ -240,6 +248,36 @@ static ssize_t ina2xx_show_value(struct device *dev,
ina2xx_get_value(data, attr->index));
}
+static ssize_t ina2xx_set_shunt(struct device *dev,
+ struct device_attribute *da,
+ const char *buf, size_t count)
+{
+ struct ina2xx_data *data = ina2xx_update_device(dev);
+ unsigned long val;
+ int status;
+
+ if (IS_ERR(data))
+ return PTR_ERR(data);
+
+ status = kstrtoul(buf, 10, &val);
+ if (status < 0)
+ return status;
+
+ if (val == 0 ||
+ /* Values greater than the calibration factor make no sense. */
+ val > data->config->calibration_factor)
+ return -EINVAL;
+
+ mutex_lock(&data->update_lock);
+ data->rshunt = val;
+ status = ina2xx_calibrate(data);
+ mutex_unlock(&data->update_lock);
+ if (status < 0)
+ return status;
+
+ return count;
+}
+
/* shunt voltage */
static SENSOR_DEVICE_ATTR(in0_input, S_IRUGO, ina2xx_show_value, NULL,
INA2XX_SHUNT_VOLTAGE);
@@ -256,12 +294,18 @@ static SENSOR_DEVICE_ATTR(curr1_input, S_IRUGO, ina2xx_show_value, NULL,
static SENSOR_DEVICE_ATTR(power1_input, S_IRUGO, ina2xx_show_value, NULL,
INA2XX_POWER);
+/* shunt resistance */
+static SENSOR_DEVICE_ATTR(shunt_resistor, S_IRUGO | S_IWUSR,
+ ina2xx_show_value, ina2xx_set_shunt,
+ INA2XX_CALIBRATION);
+
/* pointers to created device attributes */
static struct attribute *ina2xx_attrs[] = {
&sensor_dev_attr_in0_input.dev_attr.attr,
&sensor_dev_attr_in1_input.dev_attr.attr,
&sensor_dev_attr_curr1_input.dev_attr.attr,
&sensor_dev_attr_power1_input.dev_attr.attr,
+ &sensor_dev_attr_shunt_resistor.dev_attr.attr,
NULL,
};
ATTRIBUTE_GROUPS(ina2xx);
--
2.1.3
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