diff options
| author | Bartosz Golaszewski <bgolaszewski@baylibre.com> | 2015-01-05 17:20:55 +0300 |
|---|---|---|
| committer | Guenter Roeck <linux@roeck-us.net> | 2015-01-26 08:23:59 +0300 |
| commit | 8a5fc79513afe325fd755026299d0bfdb47e42de (patch) | |
| tree | 0e61597ce857a95050ecafc262a0902d47e49e99 /drivers/hwmon/ina2xx.c | |
| parent | e794704000cf7954039b8daab9dfae2a74142f07 (diff) | |
| download | linux-8a5fc79513afe325fd755026299d0bfdb47e42de.tar.xz | |
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>
Diffstat (limited to 'drivers/hwmon/ina2xx.c')
| -rw-r--r-- | drivers/hwmon/ina2xx.c | 48 |
1 files changed, 46 insertions, 2 deletions
diff --git a/drivers/hwmon/ina2xx.c b/drivers/hwmon/ina2xx.c index 3234e571805c..49537ea80748 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 int ina2xx_do_update(struct device *dev) @@ -231,6 +236,9 @@ 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); @@ -254,6 +262,36 @@ 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); @@ -270,12 +308,18 @@ 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); |