iio: adc: Fix polling of INA219 conversion ready flag

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>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

diff --git a/drivers/iio/adc/ina2xx-adc.c b/drivers/iio/adc/ina2xx-adc.c
index 232c0b8..68884d2 100644 (file)
--- 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);