diff options
Diffstat (limited to 'drivers')
| -rw-r--r-- | drivers/hwmon/ina2xx.c | 87 |
1 files changed, 50 insertions, 37 deletions
diff --git a/drivers/hwmon/ina2xx.c b/drivers/hwmon/ina2xx.c index 62e38fa8cda2..e362a932fe8c 100644 --- a/drivers/hwmon/ina2xx.c +++ b/drivers/hwmon/ina2xx.c @@ -95,18 +95,20 @@ enum ina2xx_ids { ina219, ina226 }; struct ina2xx_config { u16 config_default; - int calibration_factor; + int calibration_value; int registers; int shunt_div; int bus_voltage_shift; int bus_voltage_lsb; /* uV */ - int power_lsb; /* uW */ + int power_lsb_factor; }; struct ina2xx_data { const struct ina2xx_config *config; long rshunt; + long current_lsb_uA; + long power_lsb_uW; struct mutex config_lock; struct regmap *regmap; @@ -116,21 +118,21 @@ struct ina2xx_data { static const struct ina2xx_config ina2xx_config[] = { [ina219] = { .config_default = INA219_CONFIG_DEFAULT, - .calibration_factor = 40960000, + .calibration_value = 4096, .registers = INA219_REGISTERS, .shunt_div = 100, .bus_voltage_shift = 3, .bus_voltage_lsb = 4000, - .power_lsb = 20000, + .power_lsb_factor = 20, }, [ina226] = { .config_default = INA226_CONFIG_DEFAULT, - .calibration_factor = 5120000, + .calibration_value = 2048, .registers = INA226_REGISTERS, .shunt_div = 400, .bus_voltage_shift = 0, .bus_voltage_lsb = 1250, - .power_lsb = 25000, + .power_lsb_factor = 25, }, }; @@ -169,12 +171,16 @@ static u16 ina226_interval_to_reg(int interval) return INA226_SHIFT_AVG(avg_bits); } +/* + * Calibration register is set to the best value, which eliminates + * truncation errors on calculating current register in hardware. + * According to datasheet (eq. 3) the best values are 2048 for + * ina226 and 4096 for ina219. They are hardcoded as calibration_value. + */ static int ina2xx_calibrate(struct ina2xx_data *data) { - u16 val = DIV_ROUND_CLOSEST(data->config->calibration_factor, - data->rshunt); - - return regmap_write(data->regmap, INA2XX_CALIBRATION, val); + return regmap_write(data->regmap, INA2XX_CALIBRATION, + data->config->calibration_value); } /* @@ -187,10 +193,6 @@ static int ina2xx_init(struct ina2xx_data *data) if (ret < 0) return ret; - /* - * Set current LSB to 1mA, shunt is in uOhms - * (equation 13 in datasheet). - */ return ina2xx_calibrate(data); } @@ -268,15 +270,15 @@ static int ina2xx_get_value(struct ina2xx_data *data, u8 reg, val = DIV_ROUND_CLOSEST(val, 1000); break; case INA2XX_POWER: - val = regval * data->config->power_lsb; + val = regval * data->power_lsb_uW; break; case INA2XX_CURRENT: - /* signed register, LSB=1mA (selected), in mA */ - val = (s16)regval; + /* signed register, result in mA */ + val = regval * data->current_lsb_uA; + val = DIV_ROUND_CLOSEST(val, 1000); break; case INA2XX_CALIBRATION: - val = DIV_ROUND_CLOSEST(data->config->calibration_factor, - regval); + val = regval; break; default: /* programmer goofed */ @@ -304,9 +306,32 @@ static ssize_t ina2xx_show_value(struct device *dev, ina2xx_get_value(data, attr->index, regval)); } -static ssize_t ina2xx_set_shunt(struct device *dev, - struct device_attribute *da, - const char *buf, size_t count) +/* + * In order to keep calibration register value fixed, the product + * of current_lsb and shunt_resistor should also be fixed and equal + * to shunt_voltage_lsb = 1 / shunt_div multiplied by 10^9 in order + * to keep the scale. + */ +static int ina2xx_set_shunt(struct ina2xx_data *data, long val) +{ + unsigned int dividend = DIV_ROUND_CLOSEST(1000000000, + data->config->shunt_div); + if (val <= 0 || val > dividend) + return -EINVAL; + + mutex_lock(&data->config_lock); + data->rshunt = val; + data->current_lsb_uA = DIV_ROUND_CLOSEST(dividend, val); + data->power_lsb_uW = data->config->power_lsb_factor * + data->current_lsb_uA; + mutex_unlock(&data->config_lock); + + return 0; +} + +static ssize_t ina2xx_store_shunt(struct device *dev, + struct device_attribute *da, + const char *buf, size_t count) { unsigned long val; int status; @@ -316,18 +341,9 @@ static ssize_t ina2xx_set_shunt(struct device *dev, 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->config_lock); - data->rshunt = val; - status = ina2xx_calibrate(data); - mutex_unlock(&data->config_lock); + status = ina2xx_set_shunt(data, val); if (status < 0) return status; - return count; } @@ -387,7 +403,7 @@ static SENSOR_DEVICE_ATTR(power1_input, S_IRUGO, ina2xx_show_value, NULL, /* shunt resistance */ static SENSOR_DEVICE_ATTR(shunt_resistor, S_IRUGO | S_IWUSR, - ina2xx_show_value, ina2xx_set_shunt, + ina2xx_show_value, ina2xx_store_shunt, INA2XX_CALIBRATION); /* update interval (ina226 only) */ @@ -448,10 +464,7 @@ static int ina2xx_probe(struct i2c_client *client, val = INA2XX_RSHUNT_DEFAULT; } - if (val <= 0 || val > data->config->calibration_factor) - return -ENODEV; - - data->rshunt = val; + ina2xx_set_shunt(data, val); ina2xx_regmap_config.max_register = data->config->registers; |