iio: adc: ina2xx: add INA236 support

The calibration divisor is not directly specified in the datasheet, but can be calculated:

I = Current_LSB * Current
Current = ShuntVoltage * CAL / calibration_divisor
CAL = 0.00512 / (Current_LSB * Rshunt)
ShuntVoltage = Vshunt / ShuntVoltage_LSB

=> I = (0.00512 / (calibration_divisor*ShuntVoltage_LSB)) * (Vshunt / Rshunt)

Ohm's law, I = Vshunt / Rshunt
=> 0.00512 / (calibration_divisor*ShuntVoltage_LSB) = 1

ShuntVoltage_LSB = 2.5 uV = 0.0000025 V
=> calibration_divisor = 2048

Signed-off-by: Chuang Zhu <git@chuang.cz>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

diff --git a/drivers/iio/adc/ina2xx-adc.c b/drivers/iio/adc/ina2xx-adc.c
index 857e1b69d6cd4d65d7ebe5de222fe92875eccdcc..dd37109a008af8cc3c6fc6757e6698d36c0518f9 100644 (file)
--- a/drivers/iio/adc/ina2xx-adc.c
+++ b/drivers/iio/adc/ina2xx-adc.c
@@ -121,7 +121,7 @@ static const struct regmap_config ina2xx_regmap_config = {
        .volatile_reg = ina2xx_is_volatile_reg,
 };
 
-enum ina2xx_ids { ina219, ina226 };
+enum ina2xx_ids { ina219, ina226, ina236 };
 
 struct ina2xx_config {
        const char *name;
@@ -175,6 +175,16 @@ static const struct ina2xx_config ina2xx_config[] = {
                .power_lsb_factor = 25,
                .chip_id = ina226,
        },
+       [ina236] = {
+               .name = "ina236",
+               .config_default = INA226_CONFIG_DEFAULT,
+               .calibration_value = 2048,
+               .shunt_voltage_lsb = 2500,
+               .bus_voltage_shift = 0,
+               .bus_voltage_lsb = 1600,
+               .power_lsb_factor = 32,
+               .chip_id = ina236,
+       },
 };
 
 static int ina2xx_read_raw(struct iio_dev *indio_dev,
@@ -499,20 +509,26 @@ static int ina2xx_write_raw(struct iio_dev *indio_dev,
                break;
 
        case IIO_CHAN_INFO_INT_TIME:
-               if (chip->config->chip_id == ina226) {
+               switch (chip->config->chip_id) {
+               case ina226:
+               case ina236:
                        if (chan->address == INA2XX_SHUNT_VOLTAGE)
                                ret = ina226_set_int_time_vshunt(chip, val2,
                                                                 &tmp);
                        else
                                ret = ina226_set_int_time_vbus(chip, val2,
                                                               &tmp);
-               } else {
+                       break;
+               case ina219:
                        if (chan->address == INA2XX_SHUNT_VOLTAGE)
                                ret = ina219_set_int_time_vshunt(chip, val2,
                                                                 &tmp);
                        else
                                ret = ina219_set_int_time_vbus(chip, val2,
                                                               &tmp);
+                       break;
+               default:
+                       ret = -EINVAL;
                }
                break;
 
@@ -727,19 +743,27 @@ static int ina2xx_conversion_ready(struct iio_dev *indio_dev)
         * For now, we do an extra read of the MASK_ENABLE register (INA226)
         * resp. the BUS_VOLTAGE register (INA219).
         */
-       if (chip->config->chip_id == ina226) {
+       switch (chip->config->chip_id) {
+       case ina226:
+       case ina236:
                ret = regmap_read(chip->regmap,
                                  INA226_MASK_ENABLE, &alert);
+               if (ret < 0)
+                       return ret;
+
                alert &= INA226_CVRF;
-       } else {
+               break;
+       case ina219:
                ret = regmap_read(chip->regmap,
                                  INA2XX_BUS_VOLTAGE, &alert);
+               if (ret < 0)
+                       return ret;
                alert &= INA219_CNVR;
+               break;
+       default:
+               return -EINVAL;
        }
 
-       if (ret < 0)
-               return ret;
-
        return !!alert;
 }
 
@@ -998,16 +1022,22 @@ static int ina2xx_probe(struct i2c_client *client)
        /* Patch the current config register with default. */
        val = chip->config->config_default;
 
-       if (type == ina226) {
+       switch (type) {
+       case ina226:
+       case ina236:
                ina226_set_average(chip, INA226_DEFAULT_AVG, &val);
                ina226_set_int_time_vbus(chip, INA226_DEFAULT_IT, &val);
                ina226_set_int_time_vshunt(chip, INA226_DEFAULT_IT, &val);
-       } else {
+               break;
+       case ina219:
                chip->avg = 1;
                ina219_set_int_time_vbus(chip, INA219_DEFAULT_IT, &val);
                ina219_set_int_time_vshunt(chip, INA219_DEFAULT_IT, &val);
                ina219_set_vbus_range_denom(chip, INA219_DEFAULT_BRNG, &val);
                ina219_set_vshunt_pga_gain(chip, INA219_DEFAULT_PGA, &val);
+               break;
+       default:
+               return -EINVAL;
        }
 
        ret = ina2xx_init(chip, val);
@@ -1017,14 +1047,20 @@ static int ina2xx_probe(struct i2c_client *client)
        }
 
        indio_dev->modes = INDIO_DIRECT_MODE;
-       if (type == ina226) {
+       switch (type) {
+       case ina226:
+       case ina236:
                indio_dev->channels = ina226_channels;
                indio_dev->num_channels = ARRAY_SIZE(ina226_channels);
                indio_dev->info = &ina226_info;
-       } else {
+               break;
+       case ina219:
                indio_dev->channels = ina219_channels;
                indio_dev->num_channels = ARRAY_SIZE(ina219_channels);
                indio_dev->info = &ina219_info;
+               break;
+       default:
+               return -EINVAL;
        }
        indio_dev->name = id ? id->name : chip->config->name;
 
@@ -1057,6 +1093,7 @@ static const struct i2c_device_id ina2xx_id[] = {
        { "ina226", ina226 },
        { "ina230", ina226 },
        { "ina231", ina226 },
+       { "ina236", ina236 },
        { }
 };
 MODULE_DEVICE_TABLE(i2c, ina2xx_id);
@@ -1082,6 +1119,10 @@ static const struct of_device_id ina2xx_of_match[] = {
                .compatible = "ti,ina231",
                .data = (void *)ina226
        },
+       {
+               .compatible = "ti,ina236",
+               .data = (void *)ina236
+       },
        { }
 };
 MODULE_DEVICE_TABLE(of, ina2xx_of_match);