Commit 5d389b12 authored by Maciej Purski's avatar Maciej Purski Committed by Guenter Roeck
Browse files

hwmon: (ina2xx) Make calibration register value fixed 



Calibration register is used for calculating current register in
hardware according to datasheet:
current = shunt_volt * calib_register / 2048 (ina 226)
current = shunt_volt * calib_register / 4096 (ina 219)

Fix calib_register value to 2048 for ina226 and 4096 for ina 219 in
order to avoid truncation error and provide best precision allowed
by shunt_voltage measurement. Make current scale value follow changes
of shunt_resistor from sysfs as calib_register value is now fixed.

Power_lsb value should also follow shunt_resistor changes as stated in
datasheet:
power_lsb = 25 * current_lsb (ina 226)
power_lsb = 20 * current_lsb (ina 219)

Signed-off-by: default avatarMaciej Purski <m.purski@samsung.com>
Signed-off-by: default avatarGuenter Roeck <linux@roeck-us.net>
parent cf583b42

drivers/hwmon/ina2xx.c

+50 −37
Original line number Diff line number Diff line
@@ -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 */
@@ -304,7 +306,30 @@ 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,

/*

 * 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)

{
@@ -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;

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