[PATCH v2 1/3] iio: adc: ina2xx: Shift bus voltage register to mask flag bits

[Stefan BrÃns]

Lower bits of the INA219/220 bus voltage register are conversion
status flags, properly shift the value.

When reading via IIO buffer, the value is passed on unaltered,
shifting is the responsibility of the user.

Signed-off-by: Stefan BrÃns <stefan.bruens@xxxxxxxxxxxxxx>

---

Changes in v2:
- Apply to the shunt voltage, not bus voltage register
- Shift instead of masking the LSBs

 drivers/iio/adc/ina2xx-adc.c | 26 +++++++++++++++++---------
 1 file changed, 17 insertions(+), 9 deletions(-)

diff --git a/drivers/iio/adc/ina2xx-adc.c b/drivers/iio/adc/ina2xx-adc.c
index 3aff9556678f..84094235ff7e 100644
--- a/drivers/iio/adc/ina2xx-adc.c
+++ b/drivers/iio/adc/ina2xx-adc.c
@@ -44,7 +44,6 @@
 
 #define INA226_MASK_ENABLE		0x06
 #define INA226_CVRF			BIT(3)
-#define INA219_CNVR			BIT(1)
 
 #define INA2XX_MAX_REGISTERS            8
 
@@ -79,6 +78,11 @@
 #define INA226_ITS_MASK		GENMASK(5, 3)
 #define INA226_SHIFT_ITS(val)	((val) << 3)
 
+/* INA219 Bus voltage register, low bits are flags */
+#define INA219_OVF		BIT(0)
+#define INA219_CNVR		BIT(1)
+#define INA219_BUS_VOLTAGE_SHIFT	3
+
 /* Cosmetic macro giving the sampling period for a full P=UxI cycle */
 #define SAMPLING_PERIOD(c)	((c->int_time_vbus + c->int_time_vshunt) \
 				 * c->avg)
@@ -112,7 +116,7 @@ struct ina2xx_config {
 	u16 config_default;
 	int calibration_factor;
 	int shunt_div;
-	int bus_voltage_shift;
+	int bus_voltage_shift;	/* position of lsb */
 	int bus_voltage_lsb;	/* uV */
 	int power_lsb;		/* uW */
 	enum ina2xx_ids chip_id;
@@ -135,7 +139,7 @@ static const struct ina2xx_config ina2xx_config[] = {
 		.config_default = INA219_CONFIG_DEFAULT,
 		.calibration_factor = 40960000,
 		.shunt_div = 100,
-		.bus_voltage_shift = 3,
+		.bus_voltage_shift = INA219_BUS_VOLTAGE_SHIFT,
 		.bus_voltage_lsb = 4000,
 		.power_lsb = 20000,
 		.chip_id = ina219,
@@ -170,6 +174,9 @@ static int ina2xx_read_raw(struct iio_dev *indio_dev,
 		else
 			*val  = regval;
 
+		if (chan->address == INA2XX_BUS_VOLTAGE)
+			*val >>= chip->config->bus_voltage_shift;
+
 		return IIO_VAL_INT;
 
 	case IIO_CHAN_INFO_OVERSAMPLING_RATIO:
@@ -203,9 +210,9 @@ static int ina2xx_read_raw(struct iio_dev *indio_dev,
 			return IIO_VAL_FRACTIONAL;
 
 		case INA2XX_BUS_VOLTAGE:
-			/* processed (mV) = raw*lsb (uV) / (1000 << shift) */
+			/* processed (mV) = raw * lsb (uV) / 1000 */
 			*val = chip->config->bus_voltage_lsb;
-			*val2 = 1000 << chip->config->bus_voltage_shift;
+			*val2 = 1000;
 			return IIO_VAL_FRACTIONAL;
 
 		case INA2XX_POWER:
@@ -532,7 +539,7 @@ static ssize_t ina2xx_shunt_resistor_store(struct device *dev,
  * Sampling Freq is a consequence of the integration times of
  * the Voltage channels.
  */
-#define INA219_CHAN_VOLTAGE(_index, _address) { \
+#define INA219_CHAN_VOLTAGE(_index, _address, _shift) { \
 	.type = IIO_VOLTAGE, \
 	.address = (_address), \
 	.indexed = 1, \
@@ -544,7 +551,8 @@ static ssize_t ina2xx_shunt_resistor_store(struct device *dev,
 	.scan_index = (_index), \
 	.scan_type = { \
 		.sign = 'u', \
-		.realbits = 16, \
+		.shift = _shift, \
+		.realbits = 16 - _shift, \
 		.storagebits = 16, \
 		.endianness = IIO_LE, \
 	} \
@@ -579,8 +587,8 @@ static const struct iio_chan_spec ina226_channels[] = {
 };
 
 static const struct iio_chan_spec ina219_channels[] = {
-	INA219_CHAN_VOLTAGE(0, INA2XX_SHUNT_VOLTAGE),
-	INA219_CHAN_VOLTAGE(1, INA2XX_BUS_VOLTAGE),
+	INA219_CHAN_VOLTAGE(0, INA2XX_SHUNT_VOLTAGE, 0),
+	INA219_CHAN_VOLTAGE(1, INA2XX_BUS_VOLTAGE, INA219_BUS_VOLTAGE_SHIFT),
 	INA219_CHAN(IIO_POWER, 2, INA2XX_POWER),
 	INA219_CHAN(IIO_CURRENT, 3, INA2XX_CURRENT),
 	IIO_CHAN_SOFT_TIMESTAMP(4),
-- 
2.14.3