iio/adc: (max1363) Add support for external reference voltage

Implement external reference voltage as regulator named "vref".

Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

diff --git a/drivers/iio/adc/max1363.c b/drivers/iio/adc/max1363.c
index c5e46c6..6c1cfb7 100644 (file)
--- a/drivers/iio/adc/max1363.c
+++ b/drivers/iio/adc/max1363.c
@@ -163,6 +163,8 @@ struct max1363_chip_info {
  * @mask_low:          bitmask for enabled low thresholds
  * @thresh_high:       high threshold values
  * @thresh_low:                low threshold values
+ * @vref:              Reference voltage regulator
+ * @vref_uv:           Actual (external or internal) reference voltage
  */
 struct max1363_state {
        struct i2c_client               *client;
@@ -182,6 +184,8 @@ struct max1363_state {
        /* 4x unipolar first then the fours bipolar ones */
        s16                             thresh_high[8];
        s16                             thresh_low[8];
+       struct regulator                *vref;
+       u32                             vref_uv;
 };
 
 #define MAX1363_MODE_SINGLE(_num, _mask) {                             \
@@ -393,6 +397,8 @@ static int max1363_read_raw(struct iio_dev *indio_dev,
 {
        struct max1363_state *st = iio_priv(indio_dev);
        int ret;
+       unsigned long scale_uv;
+
        switch (m) {
        case IIO_CHAN_INFO_RAW:
                ret = max1363_read_single_chan(indio_dev, chan, val, m);
@@ -400,16 +406,10 @@ static int max1363_read_raw(struct iio_dev *indio_dev,
                        return ret;
                return IIO_VAL_INT;
        case IIO_CHAN_INFO_SCALE:
-               if ((1 << (st->chip_info->bits + 1)) >
-                   st->chip_info->int_vref_mv) {
-                       *val = 0;
-                       *val2 = 500000;
-                       return IIO_VAL_INT_PLUS_MICRO;
-               } else {
-                       *val = (st->chip_info->int_vref_mv)
-                               >> st->chip_info->bits;
-                       return IIO_VAL_INT;
-               }
+               scale_uv = st->vref_uv >> st->chip_info->bits;
+               *val = scale_uv / 1000;
+               *val2 = (scale_uv % 1000) * 1000;
+               return IIO_VAL_INT_PLUS_MICRO;
        default:
                return -EINVAL;
        }
@@ -1390,12 +1390,16 @@ static const struct max1363_chip_info max1363_chip_info_tbl[] = {
 
 static int max1363_initial_setup(struct max1363_state *st)
 {
-       st->setupbyte = MAX1363_SETUP_AIN3_IS_AIN3_REF_IS_VDD
-               | MAX1363_SETUP_POWER_UP_INT_REF
-               | MAX1363_SETUP_INT_CLOCK
+       st->setupbyte = MAX1363_SETUP_INT_CLOCK
                | MAX1363_SETUP_UNIPOLAR
                | MAX1363_SETUP_NORESET;
 
+       if (st->vref)
+               st->setupbyte |= MAX1363_SETUP_AIN3_IS_REF_EXT_TO_REF;
+       else
+               st->setupbyte |= MAX1363_SETUP_POWER_UP_INT_REF
+                 | MAX1363_SETUP_AIN3_IS_AIN3_REF_IS_INT;
+
        /* Set scan mode writes the config anyway so wait until then */
        st->setupbyte = MAX1363_SETUP_BYTE(st->setupbyte);
        st->current_mode = &max1363_mode_table[st->chip_info->default_mode];
@@ -1491,6 +1495,7 @@ static int max1363_probe(struct i2c_client *client,
        int ret;
        struct max1363_state *st;
        struct iio_dev *indio_dev;
+       struct regulator *vref;
 
        indio_dev = iio_device_alloc(sizeof(struct max1363_state));
        if (indio_dev == NULL) {
@@ -1521,6 +1526,23 @@ static int max1363_probe(struct i2c_client *client,
        st->chip_info = &max1363_chip_info_tbl[id->driver_data];
        st->client = client;
 
+       st->vref_uv = st->chip_info->int_vref_mv * 1000;
+       vref = devm_regulator_get(&client->dev, "vref");
+       if (!IS_ERR(vref)) {
+               int vref_uv;
+
+               ret = regulator_enable(vref);
+               if (ret)
+                       goto error_disable_reg;
+               st->vref = vref;
+               vref_uv = regulator_get_voltage(vref);
+               if (vref_uv <= 0) {
+                       ret = -EINVAL;
+                       goto error_disable_reg;
+               }
+               st->vref_uv = vref_uv;
+       }
+
        ret = max1363_alloc_scan_masks(indio_dev);
        if (ret)
                goto error_disable_reg;
@@ -1562,6 +1584,8 @@ static int max1363_probe(struct i2c_client *client,
 error_uninit_buffer:
        iio_triggered_buffer_cleanup(indio_dev);
 error_disable_reg:
+       if (st->vref)
+               regulator_disable(st->vref);
        regulator_disable(st->reg);
 error_unregister_map:
        iio_map_array_unregister(indio_dev);
@@ -1578,6 +1602,8 @@ static int max1363_remove(struct i2c_client *client)
 
        iio_device_unregister(indio_dev);
        iio_triggered_buffer_cleanup(indio_dev);
+       if (st->vref)
+               regulator_disable(st->vref);
        regulator_disable(st->reg);
        iio_map_array_unregister(indio_dev);
        iio_device_free(indio_dev);