iio: adc: ad799x: cache regulator voltages during probe

Since the reference voltage for this ADC is not expected to
change at runtime, determine the active reference voltage (either VREF
or VCC) during probe() and cache it in a single variable in the state
structure.

Suggested-by: Jonathan Cameron <jic23@kernel.org>
Suggested-by: David Lechner <dlechner@baylibre.com>
Reviewed-by: David Lechner <dlechner@baylibre.com>
Signed-off-by: Archit Anant <architanant5@gmail.com>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@intel.com>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

diff --git a/drivers/iio/adc/ad799x.c b/drivers/iio/adc/ad799x.c
index d8389b6e19b5567d60b7d39be9acaf0cb2f47184..e37bb64edd2b627693361b50d427b7f8827053f2 100644 (file)
--- a/drivers/iio/adc/ad799x.c
+++ b/drivers/iio/adc/ad799x.c
@@ -30,6 +30,7 @@
 #include <linux/slab.h>
 #include <linux/sysfs.h>
 #include <linux/types.h>
+#include <linux/units.h>
 
 #include <linux/iio/buffer.h>
 #include <linux/iio/events.h>
@@ -135,6 +136,9 @@ struct ad799x_state {
        u16                             config;
 
        unsigned int                    transfer_size;
+
+       int                             vref_uV;
+
        IIO_DECLARE_BUFFER_WITH_TS(__be16, rx_buf, AD799X_MAX_CHANNELS);
 };
 
@@ -303,14 +307,7 @@ static int ad799x_read_raw(struct iio_dev *indio_dev,
                        GENMASK(chan->scan_type.realbits - 1, 0);
                return IIO_VAL_INT;
        case IIO_CHAN_INFO_SCALE:
-               if (st->vref)
-                       ret = regulator_get_voltage(st->vref);
-               else
-                       ret = regulator_get_voltage(st->reg);
-
-               if (ret < 0)
-                       return ret;
-               *val = ret / 1000;
+               *val = st->vref_uV / (MICRO / MILLI);
                *val2 = chan->scan_type.realbits;
                return IIO_VAL_FRACTIONAL_LOG2;
        }
@@ -829,9 +826,20 @@ static int ad799x_probe(struct i2c_client *client)
                        ret = regulator_enable(st->vref);
                        if (ret)
                                goto error_disable_reg;
+                       ret = regulator_get_voltage(st->vref);
+                       if (ret < 0)
+                               goto error_disable_vref;
+                       st->vref_uV = ret;
                }
        }
 
+       if (!st->vref) {
+               ret = regulator_get_voltage(st->reg);
+               if (ret < 0)
+                       goto error_disable_reg;
+               st->vref_uV = ret;
+       }
+
        st->client = client;
 
        indio_dev->name = id->name;