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>

1 files changed, 39 insertions, 13 deletions

diff --git a/drivers/iio/adc/max1363.c b/drivers/iio/adc/max1363.c
index c5e46c62ffbb..6c1cfb74bdfc 100644
--- 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);