hwmon: (ina2xx) make shunt resistance configurable at run-time
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@baylibre.com> Signed-off-by: Guenter Roeck <linux@roeck-us.net>
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@ -44,6 +44,7 @@ The INA226 monitors both a shunt voltage drop and bus supply voltage.
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The INA230 is a high or low side current shunt and power monitor with an I2C
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interface. The INA230 monitors both a shunt voltage drop and bus supply voltage.
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The shunt value in micro-ohms can be set via platform data or device tree.
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Please refer to the Documentation/devicetree/bindings/i2c/ina2xx.txt for bindings
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The shunt value in micro-ohms can be set via platform data or device tree at
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compile-time or via the shunt_resistor attribute in sysfs at run-time. Please
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refer to the Documentation/devicetree/bindings/i2c/ina2xx.txt for bindings
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if the device tree is used.
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@ -115,6 +115,12 @@ static const struct ina2xx_config ina2xx_config[] = {
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},
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};
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static int ina2xx_calibrate(struct ina2xx_data *data)
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{
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return i2c_smbus_write_word_swapped(data->client, INA2XX_CALIBRATION,
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data->config->calibration_factor / data->rshunt);
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}
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/*
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* Initialize the configuration and calibration registers.
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*/
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@ -133,8 +139,7 @@ static int ina2xx_init(struct ina2xx_data *data)
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* Set current LSB to 1mA, shunt is in uOhms
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* (equation 13 in datasheet).
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*/
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return i2c_smbus_write_word_swapped(client, INA2XX_CALIBRATION,
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data->config->calibration_factor / data->rshunt);
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return ina2xx_calibrate(data);
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}
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static int ina2xx_do_update(struct device *dev)
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@ -231,6 +236,9 @@ static int ina2xx_get_value(struct ina2xx_data *data, u8 reg)
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/* signed register, LSB=1mA (selected), in mA */
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val = (s16)data->regs[reg];
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break;
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case INA2XX_CALIBRATION:
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val = data->config->calibration_factor / data->regs[reg];
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break;
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default:
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/* programmer goofed */
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WARN_ON_ONCE(1);
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@ -254,6 +262,36 @@ static ssize_t ina2xx_show_value(struct device *dev,
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ina2xx_get_value(data, attr->index));
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}
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static ssize_t ina2xx_set_shunt(struct device *dev,
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struct device_attribute *da,
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const char *buf, size_t count)
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{
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struct ina2xx_data *data = ina2xx_update_device(dev);
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unsigned long val;
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int status;
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if (IS_ERR(data))
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return PTR_ERR(data);
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status = kstrtoul(buf, 10, &val);
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if (status < 0)
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return status;
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if (val == 0 ||
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/* Values greater than the calibration factor make no sense. */
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val > data->config->calibration_factor)
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return -EINVAL;
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mutex_lock(&data->update_lock);
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data->rshunt = val;
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status = ina2xx_calibrate(data);
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mutex_unlock(&data->update_lock);
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if (status < 0)
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return status;
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return count;
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}
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/* shunt voltage */
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static SENSOR_DEVICE_ATTR(in0_input, S_IRUGO, ina2xx_show_value, NULL,
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INA2XX_SHUNT_VOLTAGE);
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@ -270,12 +308,18 @@ static SENSOR_DEVICE_ATTR(curr1_input, S_IRUGO, ina2xx_show_value, NULL,
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static SENSOR_DEVICE_ATTR(power1_input, S_IRUGO, ina2xx_show_value, NULL,
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INA2XX_POWER);
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/* shunt resistance */
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static SENSOR_DEVICE_ATTR(shunt_resistor, S_IRUGO | S_IWUSR,
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ina2xx_show_value, ina2xx_set_shunt,
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INA2XX_CALIBRATION);
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/* pointers to created device attributes */
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static struct attribute *ina2xx_attrs[] = {
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&sensor_dev_attr_in0_input.dev_attr.attr,
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&sensor_dev_attr_in1_input.dev_attr.attr,
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&sensor_dev_attr_curr1_input.dev_attr.attr,
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&sensor_dev_attr_power1_input.dev_attr.attr,
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&sensor_dev_attr_shunt_resistor.dev_attr.attr,
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NULL,
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};
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ATTRIBUTE_GROUPS(ina2xx);
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