[PATCH v2 3/3] iio: adc: Fix polling of INA219 conversion ready flag

Stefan Brüns
2017-05-24T00:09:35Z

While the INA226 has a conversion ready flag (CVRF) in the R/W Mask/Enable
register with read-to-clear semantics, the corresponding bit of the INA219
(CNVR) is part of the bus voltage register. The flag is cleared by reading
the power register.

Signed-off-by: Stefan Brüns <stefan.bruens@rwth-aachen.de>
---
drivers/iio/adc/ina2xx-adc.c | 36 +++++++++++++++++++++++++++++-------
1 file changed, 29 insertions(+), 7 deletions(-)

diff --git a/drivers/iio/adc/ina2xx-adc.c b/drivers/iio/adc/ina2xx-adc.c
index 232c0b80d658..68884d26b50c 100644
--- a/drivers/iio/adc/ina2xx-adc.c
+++ b/drivers/iio/adc/ina2xx-adc.c
@@ -44,6 +44,7 @@

#define INA226_MASK_ENABLE 0x06
#define INA226_CVRF BIT(3)
+#define INA219_CNVR BIT(1)

#define INA2XX_MAX_REGISTERS 8

@@ -592,6 +593,7 @@ static int ina2xx_work_buffer(struct iio_dev *indio_dev)
int bit, ret, i = 0;
s64 time_a, time_b;
unsigned int alert;
+ int cnvr_need_clear = 0;

time_a = iio_get_time_ns(indio_dev);

@@ -603,22 +605,30 @@ static int ina2xx_work_buffer(struct iio_dev *indio_dev)
* we check the ConVersionReadyFlag.
* On hardware that supports using the ALERT pin to toggle a
* GPIO a triggered buffer could be used instead.
- * For now, we pay for that extra read of the ALERT register
+ * For now, we do an extra read of the MASK_ENABLE register (INA226)
+ * resp. the BUS_VOLTAGE register (INA219).
*/
if (!chip->allow_async_readout)
do {
- ret = regmap_read(chip->regmap, INA226_MASK_ENABLE,
- &alert);
+ if (chip->config->chip_id == ina226) {
+ ret = regmap_read(chip->regmap,
+ INA226_MASK_ENABLE, &alert);
+ alert &= INA226_CVRF;
+ } else {
+ ret = regmap_read(chip->regmap,
+ INA2XX_BUS_VOLTAGE, &alert);
+ alert &= INA219_CNVR;
+ cnvr_need_clear = alert;
+ }
+
if (ret < 0)
return ret;

- alert &= INA226_CVRF;
} while (!alert);

/*
- * Single register reads: bulk_read will not work with ina226
- * as there is no auto-increment of the address register for
- * data length longer than 16bits.
+ * Single register reads: bulk_read will not work with ina226/219
+ * as there is no auto-increment of the register pointer.
*/
for_each_set_bit(bit, indio_dev->active_scan_mask,
indio_dev->masklength) {
@@ -630,6 +640,18 @@ static int ina2xx_work_buffer(struct iio_dev *indio_dev)
return ret;

data[i++] = val;
+
+ if (INA2XX_SHUNT_VOLTAGE + bit == INA2XX_POWER)
+ cnvr_need_clear = 0;
+ }
+
+ /* Dummy read on INA219 power register to clear CNVR flag */
+ if (cnvr_need_clear && chip->config->chip_id == ina219) {
+ unsigned int val;
+
+ ret = regmap_read(chip->regmap, INA2XX_POWER, &val);
+ if (ret < 0)
+ return ret;
}

time_b = iio_get_time_ns(indio_dev);
--
2.12.2