iio: light: vl6180: Cleanup als_gain lookup, avoid register readback

Instead of manually iterating the array of allowed gain values, use
find_closest. Storing the current gain setting avoids accessing the
hardware on each query.

Signed-off-by: Stefan Brüns <stefan.bruens@rwth-aachen.de>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

diff --git a/drivers/iio/light/vl6180.c b/drivers/iio/light/vl6180.c
index d2a57596f4489f37569f8969f910ed772aa4b95d..561a993a2723b0a3f55d15648ee1a9f96bab41e6 100644 (file)
--- a/drivers/iio/light/vl6180.c
+++ b/drivers/iio/light/vl6180.c
@@ -24,6 +24,7 @@
 #include <linux/err.h>
 #include <linux/of.h>
 #include <linux/delay.h>
+#include <linux/util_macros.h>
 
 #include <linux/iio/iio.h>
 #include <linux/iio/sysfs.h>
@@ -86,6 +87,7 @@
 struct vl6180_data {
        struct i2c_client *client;
        struct mutex lock;
+       unsigned int als_gain_milli;
        unsigned int als_it_ms;
 };
 
@@ -276,19 +278,17 @@ static const struct iio_chan_spec vl6180_channels[] = {
 };
 
 /*
- * Columns 3 & 4 represent the same value in decimal and hex notations.
- * Kept in order to avoid the datatype conversion while reading the
- * hardware_gain.
+ * Available Ambient Light Sensor gain settings, 1/1000th, and
+ * corresponding setting for the VL6180_ALS_GAIN register
  */
-static const int vl6180_als_gain[8][4] = {
-       { 1,    0,      70,     VL6180_ALS_GAIN_1 },
-       { 1,    250000, 69,     VL6180_ALS_GAIN_1_25 },
-       { 1,    670000, 68,     VL6180_ALS_GAIN_1_67 },
-       { 2,    500000, 67,     VL6180_ALS_GAIN_2_5 },
-       { 5,    0,      66,     VL6180_ALS_GAIN_5 },
-       { 10,   0,      65,     VL6180_ALS_GAIN_10 },
-       { 20,   0,      64,     VL6180_ALS_GAIN_20 },
-       { 40,   0,      71,     VL6180_ALS_GAIN_40 }
+static const int vl6180_als_gain_tab[8] = {
+       1000, 1250, 1670, 2500, 5000, 10000, 20000, 40000
+};
+static const u8 vl6180_als_gain_tab_bits[8] = {
+       VL6180_ALS_GAIN_1,    VL6180_ALS_GAIN_1_25,
+       VL6180_ALS_GAIN_1_67, VL6180_ALS_GAIN_2_5,
+       VL6180_ALS_GAIN_5,    VL6180_ALS_GAIN_10,
+       VL6180_ALS_GAIN_20,   VL6180_ALS_GAIN_40
 };
 
 static int vl6180_read_raw(struct iio_dev *indio_dev,
@@ -296,7 +296,7 @@ static int vl6180_read_raw(struct iio_dev *indio_dev,
                                int *val, int *val2, long mask)
 {
        struct vl6180_data *data = iio_priv(indio_dev);
-       int ret, i;
+       int ret;
 
        switch (mask) {
        case IIO_CHAN_INFO_RAW:
@@ -328,17 +328,11 @@ static int vl6180_read_raw(struct iio_dev *indio_dev,
 
                return IIO_VAL_INT_PLUS_MICRO;
        case IIO_CHAN_INFO_HARDWAREGAIN:
-               ret = vl6180_read_byte(data->client, VL6180_ALS_GAIN);
-               if (ret < 0)
-                       return -EINVAL;
-               for (i = 0; i < ARRAY_SIZE(vl6180_als_gain); i++) {
-                       if (ret == vl6180_als_gain[i][2]) {
-                               *val = vl6180_als_gain[i][0];
-                               *val2 = vl6180_als_gain[i][1];
-                       }
-               }
+               *val = data->als_gain_milli;
+               *val2 = 1000;
+
+               return IIO_VAL_FRACTIONAL;
 
-               return IIO_VAL_INT_PLUS_MICRO;
        default:
                return -EINVAL;
        }
@@ -364,25 +358,33 @@ static int vl6180_hold(struct vl6180_data *data, bool hold)
 
 static int vl6180_set_als_gain(struct vl6180_data *data, int val, int val2)
 {
-       int i, ret;
-
-       for (i = 0; i < ARRAY_SIZE(vl6180_als_gain); i++) {
-               if (val == vl6180_als_gain[i][0] &&
-                       val2 == vl6180_als_gain[i][1]) {
-                       mutex_lock(&data->lock);
-                       ret = vl6180_hold(data, true);
-                       if (ret < 0)
-                               goto fail;
-                       ret = vl6180_write_byte(data->client, VL6180_ALS_GAIN,
-                               vl6180_als_gain[i][3]);
-fail:
-                       vl6180_hold(data, false);
-                       mutex_unlock(&data->lock);
-                       return ret;
-               }
-       }
+       int i, ret, gain;
+
+       if (val < 1 || val > 40)
+               return -EINVAL;
 
-       return -EINVAL;
+       gain = (val * 1000000 + val2) / 1000;
+       if (gain < 1 || gain > 40000)
+               return -EINVAL;
+
+       i = find_closest(gain, vl6180_als_gain_tab,
+                        ARRAY_SIZE(vl6180_als_gain_tab));
+
+       mutex_lock(&data->lock);
+       ret = vl6180_hold(data, true);
+       if (ret < 0)
+               goto fail;
+
+       ret = vl6180_write_byte(data->client, VL6180_ALS_GAIN,
+                               vl6180_als_gain_tab_bits[i]);
+
+       if (ret >= 0)
+               data->als_gain_milli = vl6180_als_gain_tab[i];
+
+fail:
+       vl6180_hold(data, false);
+       mutex_unlock(&data->lock);
+       return ret;
 }
 
 static int vl6180_set_it(struct vl6180_data *data, int val, int val2)
@@ -478,6 +480,7 @@ static int vl6180_init(struct vl6180_data *data)
                return ret;
 
        /* ALS gain: 1 */
+       data->als_gain_milli = 1000;
        ret = vl6180_write_byte(client, VL6180_ALS_GAIN, VL6180_ALS_GAIN_1);
        if (ret < 0)
                return ret;