Commit 7e420b6a authored by Guenter Roeck's avatar Guenter Roeck
Browse files

hwmon: (ina238) Simplify voltage register accesses 



Calculate voltage LSB values in the probe function and use throughout
the code.

Use a single function to read all voltages, independently of the register
width. Use the pre-calculated LSB values to convert register values to
voltages and do not rely on runtime chip specific code.

Use ROUND_CLOSEST functions instead of divide operations to reduce
rounding errors.

Reviewed-by: default avatarChris Packham <chris.packham@alliedtelesis.co.nz>
Tested-by: Chris Packham <chris.packham@alliedtelesis.co.nz> # INA780
Signed-off-by: default avatarGuenter Roeck <linux@roeck-us.net>
parent 4a4fcd61

drivers/hwmon/ina238.c

+53 −108
Original line number Diff line number Diff line
@@ -101,9 +101,11 @@ 
#define INA238_CALIBRATION_VALUE	16384

#define INA238_FIXED_SHUNT		20000



#define INA238_SHUNT_VOLTAGE_LSB	5 /* 5 uV/lsb */

#define INA238_BUS_VOLTAGE_LSB		3125 /* 3.125 mV/lsb */

#define SQ52206_BUS_VOLTAGE_LSB		3750 /* 3.75 mV/lsb */

#define INA238_SHUNT_VOLTAGE_LSB	5000	/* 5 uV/lsb, in nV */

#define INA238_BUS_VOLTAGE_LSB		3125000	/* 3.125 mV/lsb, in nV */

#define SQ52206_BUS_VOLTAGE_LSB		3750000	/* 3.75 mV/lsb, in nV */



#define NUNIT_PER_MUNIT		1000000	/* n[AV] -> m[AV] */



static const struct regmap_config ina238_regmap_config = {

	.max_register = INA238_REGISTERS,
@@ -118,9 +120,9 @@ struct ina238_config { 
	bool has_power_highest;		/* chip detection power peak */

	bool has_energy;		/* chip detection energy */

	u8 temp_resolution;		/* temperature register resolution in bit */

	u32 power_calculate_factor;	/* fixed parameter for power calculation, from datasheet */

	u16 config_default;		/* Power-on default state */

	int bus_voltage_lsb;		/* use for temperature calculate, uV/lsb */

	u32 power_calculate_factor;	/* fixed parameter for power calculation, from datasheet */

	u32 bus_voltage_lsb;		/* bus voltage LSB, in nV */

	int current_lsb;		/* current LSB, in uA */

};
@@ -131,6 +133,7 @@ struct ina238_data { 
	struct regmap *regmap;

	u32 rshunt;

	int gain;

	u32 voltage_lsb[2];		/* shunt, bus voltage LSB, in nV */

	int current_lsb;		/* current LSB, in uA */

	int power_lsb;			/* power LSB, in uW */

	int energy_lsb;			/* energy LSB, in uJ */
@@ -226,45 +229,28 @@ static int ina238_read_field_s20(const struct i2c_client *client, u8 reg, s32 *v 
	return 0;

}



static int ina228_read_shunt_voltage(struct device *dev, u32 attr, int channel,

				     long *val)

static int ina228_read_voltage(struct ina238_data *data, int channel, long *val)

{

	struct ina238_data *data = dev_get_drvdata(dev);

	int regval;

	int err;

	int reg = channel ? INA238_BUS_VOLTAGE : INA238_SHUNT_VOLTAGE;

	u32 lsb = data->voltage_lsb[channel];

	u32 factor = NUNIT_PER_MUNIT;

	int err, regval;



	err = ina238_read_field_s20(data->client, INA238_SHUNT_VOLTAGE, &regval);

	if (data->config->has_20bit_voltage_current) {

		err = ina238_read_field_s20(data->client, reg, &regval);

		if (err)

			return err;



	/*

	 * gain of 1 -> LSB / 4

	 * This field has 16 bit on ina238. ina228 adds another 4 bits of

	 * precision. ina238 conversion factors can still be applied when

	 * dividing by 16.

	 */

	*val = (regval * INA238_SHUNT_VOLTAGE_LSB) * data->gain / (1000 * 4) / 16;

	return 0;

}



static int ina228_read_bus_voltage(struct device *dev, u32 attr, int channel,

				   long *val)

{

	struct ina238_data *data = dev_get_drvdata(dev);

	int regval;

	int err;



	err = ina238_read_field_s20(data->client, INA238_BUS_VOLTAGE, &regval);

		/* Adjust accuracy: LSB in units of 500 pV */

		lsb /= 8;

		factor *= 2;

	} else {

		err = regmap_read(data->regmap, reg, &regval);

		if (err)

			return err;

		regval = (s16)regval;

	}



	/*

	 * gain of 1 -> LSB / 4

	 * This field has 16 bit on ina238. ina228 adds another 4 bits of

	 * precision. ina238 conversion factors can still be applied when

	 * dividing by 16.

	 */

	*val = (regval * data->config->bus_voltage_lsb) / 1000 / 16;

	*val = DIV_S64_ROUND_CLOSEST((s64)regval * lsb, factor);

	return 0;

}
@@ -272,18 +258,16 @@ static int ina238_read_in(struct device *dev, u32 attr, int channel, 
			  long *val)

{

	struct ina238_data *data = dev_get_drvdata(dev);

	int reg, mask;

	int reg, mask = 0;

	int regval;

	int err;



	if (attr == hwmon_in_input)

		return ina228_read_voltage(data, channel, val);



	switch (channel) {

	case 0:

		switch (attr) {

		case hwmon_in_input:

			if (data->config->has_20bit_voltage_current)

				return ina228_read_shunt_voltage(dev, attr, channel, val);

			reg = INA238_SHUNT_VOLTAGE;

			break;

		case hwmon_in_max:

			reg = INA238_SHUNT_OVER_VOLTAGE;

			break;
@@ -304,11 +288,6 @@ static int ina238_read_in(struct device *dev, u32 attr, int channel, 
		break;

	case 1:

		switch (attr) {

		case hwmon_in_input:

			if (data->config->has_20bit_voltage_current)

				return ina228_read_bus_voltage(dev, attr, channel, val);

			reg = INA238_BUS_VOLTAGE;

			break;

		case hwmon_in_max:

			reg = INA238_BUS_OVER_VOLTAGE;

			break;
@@ -335,72 +314,35 @@ static int ina238_read_in(struct device *dev, u32 attr, int channel, 
	if (err < 0)

		return err;



	switch (attr) {

	case hwmon_in_input:

	case hwmon_in_max:

	case hwmon_in_min:

		/* signed register, value in mV */

		regval = (s16)regval;

		if (channel == 0)

			/* gain of 1 -> LSB / 4 */

			*val = (regval * INA238_SHUNT_VOLTAGE_LSB) *

				data->gain / (1000 * 4);

		else

			*val = (regval * data->config->bus_voltage_lsb) / 1000;

		break;

	case hwmon_in_max_alarm:

	case hwmon_in_min_alarm:

	if (mask)

		*val = !!(regval & mask);

		break;

	}

	else

		*val = DIV_S64_ROUND_CLOSEST((s64)(s16)regval * data->voltage_lsb[channel],

					     NUNIT_PER_MUNIT);



	return 0;

}



static int ina238_write_in(struct device *dev, u32 attr, int channel,

			   long val)

static int ina238_write_in(struct device *dev, u32 attr, int channel, long val)

{

	struct ina238_data *data = dev_get_drvdata(dev);

	static const int low_limits[2] = {-164, 0};

	static const int high_limits[2] = {164, 150000};

	static const u8 low_regs[2] = {INA238_SHUNT_UNDER_VOLTAGE, INA238_BUS_UNDER_VOLTAGE};

	static const u8 high_regs[2] = {INA238_SHUNT_OVER_VOLTAGE, INA238_BUS_OVER_VOLTAGE};

	int regval;



	if (attr != hwmon_in_max && attr != hwmon_in_min)

		return -EOPNOTSUPP;



	/* convert decimal to register value */

	switch (channel) {

	case 0:

		/* signed value, clamp to max range +/-163 mV */

		regval = clamp_val(val, -163, 163);

		regval = (regval * 1000 * 4) /

			 (INA238_SHUNT_VOLTAGE_LSB * data->gain);

		regval = clamp_val(regval, S16_MIN, S16_MAX) & 0xffff;

	/* Initial clamp to avoid overflows */

	val = clamp_val(val, low_limits[channel], high_limits[channel]);

	val = DIV_S64_ROUND_CLOSEST((s64)val * NUNIT_PER_MUNIT, data->voltage_lsb[channel]);

	/* Final clamp to register limits */

	regval = clamp_val(val, S16_MIN, S16_MAX) & 0xffff;



	switch (attr) {

		case hwmon_in_max:

			return regmap_write(data->regmap,

					    INA238_SHUNT_OVER_VOLTAGE, regval);

	case hwmon_in_min:

			return regmap_write(data->regmap,

					    INA238_SHUNT_UNDER_VOLTAGE, regval);

		default:

			return -EOPNOTSUPP;

		}

	case 1:

		/* signed value, positive values only. Clamp to max 102.396 V */

		regval = clamp_val(val, 0, 102396);

		regval = (regval * 1000) / data->config->bus_voltage_lsb;

		regval = clamp_val(regval, 0, S16_MAX);



		switch (attr) {

		return regmap_write(data->regmap, low_regs[channel], regval);

	case hwmon_in_max:

			return regmap_write(data->regmap,

					    INA238_BUS_OVER_VOLTAGE, regval);

		case hwmon_in_min:

			return regmap_write(data->regmap,

					    INA238_BUS_UNDER_VOLTAGE, regval);

		default:

			return -EOPNOTSUPP;

		}

		return regmap_write(data->regmap, high_regs[channel], regval);

	default:

		return -EOPNOTSUPP;

	}
@@ -812,6 +754,9 @@ static int ina238_probe(struct i2c_client *client) 
		return -ENODEV;

	}



	data->voltage_lsb[0] = INA238_SHUNT_VOLTAGE_LSB * data->gain / 4;

	data->voltage_lsb[1] = data->config->bus_voltage_lsb;



	if (data->config->current_lsb)

		data->current_lsb = data->config->current_lsb;

	else