hwmon: (ina2xx) Shift INA234 shunt and current registers

The INA219 has the lowest three bits of the bus voltage register
zero-reserved, the bus_voltage_shift ina2xx_config field was introduced
to accommodate for that.

The INA234 has four bits of the bus voltage, of the shunt voltage, and
of the current registers zero-reserved but the latter two were
implemented by choosing a 16x higher shunt_div instead of a separate
field specifying a bit shift.

This is possible because shunt voltage and current are divided by
shunt_div, hence a 16x higher shunt_div results in a 16x smaller LSB for
both the shunt voltage and the current register, perfectly accounting
for the missing bit shift.

For consistency and correctness, account for the reserved bits via
shunt_voltage_shift and current_shift configuration fields as already
done for voltage registers and use the conversion constants given in the
INA234 datasheet.

Signed-off-by: Jonas Rebmann <jre@pengutronix.de>
Link: https://lore.kernel.org/r/20260303-ina234-shift-v1-2-318c33ac4480@pengutronix.de
Signed-off-by: Guenter Roeck <linux@roeck-us.net>

diff --git a/drivers/hwmon/ina2xx.c b/drivers/hwmon/ina2xx.c
index 6a2cebbb9f157a4053ff4e3abbf3b7db4fb8eee6..613ffb622b7c42b8b6090d3b4ec7b2fa412e24a4 100644 (file)
--- a/drivers/hwmon/ina2xx.c
+++ b/drivers/hwmon/ina2xx.c
@@ -135,9 +135,11 @@ struct ina2xx_config {
        bool has_update_interval;
        int calibration_value;
        int shunt_div;
+       int shunt_voltage_shift;
        int bus_voltage_shift;
        int bus_voltage_lsb;    /* uV */
        int power_lsb_factor;
+       int current_shift;
 };
 
 struct ina2xx_data {
@@ -156,59 +158,69 @@ static const struct ina2xx_config ina2xx_config[] = {
                .config_default = INA219_CONFIG_DEFAULT,
                .calibration_value = 4096,
                .shunt_div = 100,
+               .shunt_voltage_shift = 0,
                .bus_voltage_shift = 3,
                .bus_voltage_lsb = 4000,
                .power_lsb_factor = 20,
                .has_alerts = false,
                .has_ishunt = false,
                .has_power_average = false,
+               .current_shift = 0,
                .has_update_interval = false,
        },
        [ina226] = {
                .config_default = INA226_CONFIG_DEFAULT,
                .calibration_value = 2048,
                .shunt_div = 400,
+               .shunt_voltage_shift = 0,
                .bus_voltage_shift = 0,
                .bus_voltage_lsb = 1250,
                .power_lsb_factor = 25,
                .has_alerts = true,
                .has_ishunt = false,
                .has_power_average = false,
+               .current_shift = 0,
                .has_update_interval = true,
        },
        [ina234] = {
                .config_default = INA226_CONFIG_DEFAULT,
                .calibration_value = 2048,
-               .shunt_div = 400, /* 2.5 µV/LSB raw ADC reading from INA2XX_SHUNT_VOLTAGE */
+               .shunt_div = 25, /* 2.5 µV/LSB raw ADC reading from INA2XX_SHUNT_VOLTAGE */
+               .shunt_voltage_shift = 4,
                .bus_voltage_shift = 4,
                .bus_voltage_lsb = 25600,
                .power_lsb_factor = 32,
                .has_alerts = true,
                .has_ishunt = false,
                .has_power_average = false,
+               .current_shift = 4,
                .has_update_interval = true,
        },
        [ina260] = {
                .config_default = INA260_CONFIG_DEFAULT,
                .shunt_div = 400,
+               .shunt_voltage_shift = 0,
                .bus_voltage_shift = 0,
                .bus_voltage_lsb = 1250,
                .power_lsb_factor = 8,
                .has_alerts = true,
                .has_ishunt = true,
                .has_power_average = false,
+               .current_shift = 0,
                .has_update_interval = true,
        },
        [sy24655] = {
                .config_default = SY24655_CONFIG_DEFAULT,
                .calibration_value = 4096,
                .shunt_div = 400,
+               .shunt_voltage_shift = 0,
                .bus_voltage_shift = 0,
                .bus_voltage_lsb = 1250,
                .power_lsb_factor = 25,
                .has_alerts = true,
                .has_ishunt = false,
                .has_power_average = true,
+               .current_shift = 0,
                .has_update_interval = false,
        },
 };
@@ -262,7 +274,8 @@ static int ina2xx_get_value(struct ina2xx_data *data, u8 reg,
        switch (reg) {
        case INA2XX_SHUNT_VOLTAGE:
                /* signed register */
-               val = DIV_ROUND_CLOSEST((s16)regval, data->config->shunt_div);
+               val = (s16)regval >> data->config->shunt_voltage_shift;
+               val = DIV_ROUND_CLOSEST(val, data->config->shunt_div);
                break;
        case INA2XX_BUS_VOLTAGE:
                val = (regval >> data->config->bus_voltage_shift) *
@@ -274,7 +287,8 @@ static int ina2xx_get_value(struct ina2xx_data *data, u8 reg,
                break;
        case INA2XX_CURRENT:
                /* signed register, result in mA */
-               val = (s16)regval * data->current_lsb_uA;
+               val = ((s16)regval >> data->config->current_shift) *
+                 data->current_lsb_uA;
                val = DIV_ROUND_CLOSEST(val, 1000);
                break;
        case INA2XX_CALIBRATION:
@@ -368,6 +382,7 @@ static u16 ina226_alert_to_reg(struct ina2xx_data *data, int reg, long val)
        case INA2XX_SHUNT_VOLTAGE:
                val = clamp_val(val, 0, SHRT_MAX * data->config->shunt_div);
                val *= data->config->shunt_div;
+               val <<= data->config->shunt_voltage_shift;
                return clamp_val(val, 0, SHRT_MAX);
        case INA2XX_BUS_VOLTAGE:
                val = clamp_val(val, 0, 200000);
@@ -382,6 +397,7 @@ static u16 ina226_alert_to_reg(struct ina2xx_data *data, int reg, long val)
                val = clamp_val(val, INT_MIN / 1000, INT_MAX / 1000);
                /* signed register, result in mA */
                val = DIV_ROUND_CLOSEST(val * 1000, data->current_lsb_uA);
+               val <<= data->config->current_shift;
                return clamp_val(val, SHRT_MIN, SHRT_MAX);
        default:
                /* programmer goofed */