iio: light: vl6180: Add configurable inter-measurement period support

Expose the IIO_CHAN_INFO_SAMP_FREQ attribute as a way to configure the
inter-measurement period for both the IIO_DISTANCE and IIO_LIGHT
channels. The inter-measurement period must be given in milihertz.

Signed-off-by: Abhash Jha <abhashkumarjha123@gmail.com>
Link: https://patch.msgid.link/20241007152223.59008-2-abhashkumarjha123@gmail.com
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

diff --git a/drivers/iio/light/vl6180.c b/drivers/iio/light/vl6180.c
index a1b2b3c0b4c8895e0e2e07412194978998735441..67aa2f101598f90e53185bd700e8578fb0ece645 100644 (file)
--- a/drivers/iio/light/vl6180.c
+++ b/drivers/iio/light/vl6180.c
@@ -38,7 +38,9 @@
 #define VL6180_OUT_OF_RESET 0x016
 #define VL6180_HOLD 0x017
 #define VL6180_RANGE_START 0x018
+#define VL6180_RANGE_INTER_MEAS_TIME 0x01b
 #define VL6180_ALS_START 0x038
+#define VL6180_ALS_INTER_MEAS_TIME 0x03e
 #define VL6180_ALS_GAIN 0x03f
 #define VL6180_ALS_IT 0x040
 
@@ -86,6 +88,8 @@ struct vl6180_data {
        struct mutex lock;
        unsigned int als_gain_milli;
        unsigned int als_it_ms;
+       unsigned int als_meas_rate;
+       unsigned int range_meas_rate;
 };
 
 enum { VL6180_ALS, VL6180_RANGE, VL6180_PROX };
@@ -261,12 +265,14 @@ static const struct iio_chan_spec vl6180_channels[] = {
                .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
                        BIT(IIO_CHAN_INFO_INT_TIME) |
                        BIT(IIO_CHAN_INFO_SCALE) |
-                       BIT(IIO_CHAN_INFO_HARDWAREGAIN),
+                       BIT(IIO_CHAN_INFO_HARDWAREGAIN) |
+                       BIT(IIO_CHAN_INFO_SAMP_FREQ),
        }, {
                .type = IIO_DISTANCE,
                .address = VL6180_RANGE,
                .info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
-                       BIT(IIO_CHAN_INFO_SCALE),
+                       BIT(IIO_CHAN_INFO_SCALE) |
+                       BIT(IIO_CHAN_INFO_SAMP_FREQ),
        }, {
                .type = IIO_PROXIMITY,
                .address = VL6180_PROX,
@@ -333,6 +339,18 @@ static int vl6180_read_raw(struct iio_dev *indio_dev,
 
                return IIO_VAL_FRACTIONAL;
 
+       case IIO_CHAN_INFO_SAMP_FREQ:
+               switch (chan->type) {
+               case IIO_DISTANCE:
+                       *val = data->range_meas_rate;
+                       return IIO_VAL_INT;
+               case IIO_LIGHT:
+                       *val = data->als_meas_rate;
+                       return IIO_VAL_INT;
+               default:
+                       return -EINVAL;
+               }
+
        default:
                return -EINVAL;
        }
@@ -412,11 +430,23 @@ fail:
        return ret;
 }
 
+static int vl6180_meas_reg_val_from_mhz(unsigned int mhz)
+{
+       unsigned int period = DIV_ROUND_CLOSEST(1000 * 1000, mhz);
+       unsigned int reg_val = 0;
+
+       if (period > 10)
+               reg_val = period < 2550 ? (DIV_ROUND_CLOSEST(period, 10) - 1) : 254;
+
+       return reg_val;
+}
+
 static int vl6180_write_raw(struct iio_dev *indio_dev,
                             struct iio_chan_spec const *chan,
                             int val, int val2, long mask)
 {
        struct vl6180_data *data = iio_priv(indio_dev);
+       unsigned int reg_val;
 
        switch (mask) {
        case IIO_CHAN_INFO_INT_TIME:
@@ -427,6 +457,28 @@ static int vl6180_write_raw(struct iio_dev *indio_dev,
                        return -EINVAL;
 
                return vl6180_set_als_gain(data, val, val2);
+
+       case IIO_CHAN_INFO_SAMP_FREQ:
+       {
+               guard(mutex)(&data->lock);
+               switch (chan->type) {
+               case IIO_DISTANCE:
+                       data->range_meas_rate = val;
+                       reg_val = vl6180_meas_reg_val_from_mhz(val);
+                       return vl6180_write_byte(data->client,
+                               VL6180_RANGE_INTER_MEAS_TIME, reg_val);
+
+               case IIO_LIGHT:
+                       data->als_meas_rate = val;
+                       reg_val = vl6180_meas_reg_val_from_mhz(val);
+                       return vl6180_write_byte(data->client,
+                               VL6180_ALS_INTER_MEAS_TIME, reg_val);
+
+               default:
+                       return -EINVAL;
+               }
+       }
+
        default:
                return -EINVAL;
        }
@@ -473,6 +525,20 @@ static int vl6180_init(struct vl6180_data *data)
        if (ret < 0)
                return ret;
 
+       /* Default Range inter-measurement time: 50ms or 20000 mHz */
+       ret = vl6180_write_byte(client, VL6180_RANGE_INTER_MEAS_TIME,
+                               vl6180_meas_reg_val_from_mhz(20000));
+       if (ret < 0)
+               return ret;
+       data->range_meas_rate = 20000;
+
+       /* Default ALS inter-measurement time: 10ms or 100000 mHz */
+       ret = vl6180_write_byte(client, VL6180_ALS_INTER_MEAS_TIME,
+                               vl6180_meas_reg_val_from_mhz(100000));
+       if (ret < 0)
+               return ret;
+       data->als_meas_rate = 100000;
+
        /* ALS integration time: 100ms */
        data->als_it_ms = 100;
        ret = vl6180_write_word(client, VL6180_ALS_IT, VL6180_ALS_IT_100);