iio: light: vcnl4000: Add calibration bias for 4040/4200

The calibration bias is setting the LED current to change the detection
distance. Add read/write attribute for proximity calibration bias and
read attribute for available values. This is supported for vcnl4040 and
vcnl4200.
Signed-off-by: Astrid Rost <astrid.rost@axis.com>
Link: https://lore.kernel.org/r/20230613135025.2596641-9-astrid.rost@axis.comSigned-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

drivers/iio/light/vcnl4000.c

@@ -92,6 +92,7 @@
 #define VCNL4040_CONF1_PS_PERS	GENMASK(5, 4) /* Proximity interrupt persistence setting */
 #define VCNL4040_PS_CONF2_PS_INT	GENMASK(9, 8) /* Proximity interrupt mode */
 #define VCNL4040_PS_CONF3_MPS		GENMASK(6, 5) /* Proximity multi pulse number */
+#define VCNL4040_PS_MS_LED_I		GENMASK(10, 8) /* Proximity current */
 #define VCNL4040_PS_IF_AWAY		BIT(8) /* Proximity event cross low threshold */
 #define VCNL4040_PS_IF_CLOSE		BIT(9) /* Proximity event cross high threshold */
 #define VCNL4040_ALS_RISING		BIT(12) /* Ambient Light cross high threshold */
@@ -158,6 +159,17 @@ static const int vcnl4200_als_it_times[][2] = {
 	{0, 400000},
 };
 
+static const int vcnl4040_ps_calibbias_ua[][2] = {
+	{0, 50000},
+	{0, 75000},
+	{0, 100000},
+	{0, 120000},
+	{0, 140000},
+	{0, 160000},
+	{0, 180000},
+	{0, 200000},
+};
+
 static const int vcnl4040_als_persistence[] = {1, 2, 4, 8};
 static const int vcnl4040_ps_persistence[] = {1, 2, 3, 4};
 static const int vcnl4040_ps_oversampling_ratio[] = {1, 2, 4, 8};
@@ -820,6 +832,54 @@ static ssize_t vcnl4040_write_ps_oversampling_ratio(struct vcnl4000_data *data,
 	return ret;
 }
 
+static ssize_t vcnl4040_read_ps_calibbias(struct vcnl4000_data *data, int *val, int *val2)
+{
+	int ret;
+
+	ret = i2c_smbus_read_word_data(data->client, VCNL4200_PS_CONF3);
+	if (ret < 0)
+		return ret;
+
+	ret = FIELD_GET(VCNL4040_PS_MS_LED_I, ret);
+	if (ret >= ARRAY_SIZE(vcnl4040_ps_calibbias_ua))
+		return -EINVAL;
+
+	*val = vcnl4040_ps_calibbias_ua[ret][0];
+	*val2 = vcnl4040_ps_calibbias_ua[ret][1];
+
+	return ret;
+}
+
+static ssize_t vcnl4040_write_ps_calibbias(struct vcnl4000_data *data, int val)
+{
+	unsigned int i;
+	int ret;
+	u16 regval;
+
+	for (i = 0; i < ARRAY_SIZE(vcnl4040_ps_calibbias_ua); i++) {
+		if (val == vcnl4040_ps_calibbias_ua[i][1])
+			break;
+	}
+
+	if (i >= ARRAY_SIZE(vcnl4040_ps_calibbias_ua))
+		return -EINVAL;
+
+	mutex_lock(&data->vcnl4000_lock);
+
+	ret = i2c_smbus_read_word_data(data->client, VCNL4200_PS_CONF3);
+	if (ret < 0)
+		goto out_unlock;
+
+	regval = (ret & ~VCNL4040_PS_MS_LED_I);
+	regval |= FIELD_PREP(VCNL4040_PS_MS_LED_I, i);
+	ret = i2c_smbus_write_word_data(data->client, VCNL4200_PS_CONF3,
+					regval);
+
+out_unlock:
+	mutex_unlock(&data->vcnl4000_lock);
+	return ret;
+}
+
 static int vcnl4000_read_raw(struct iio_dev *indio_dev,
 				struct iio_chan_spec const *chan,
 				int *val, int *val2, long mask)
@@ -880,6 +940,16 @@ static int vcnl4000_read_raw(struct iio_dev *indio_dev,
 		default:
 			return -EINVAL;
 		}
+	case IIO_CHAN_INFO_CALIBBIAS:
+		switch (chan->type) {
+		case IIO_PROXIMITY:
+			ret = vcnl4040_read_ps_calibbias(data, val, val2);
+			if (ret < 0)
+				return ret;
+			return IIO_VAL_INT_PLUS_MICRO;
+		default:
+			return -EINVAL;
+		}
 	default:
 		return -EINVAL;
 	}
@@ -910,6 +980,13 @@ static int vcnl4040_write_raw(struct iio_dev *indio_dev,
 		default:
 			return -EINVAL;
 		}
+	case IIO_CHAN_INFO_CALIBBIAS:
+		switch (chan->type) {
+		case IIO_PROXIMITY:
+			return vcnl4040_write_ps_calibbias(data, val2);
+		default:
+			return -EINVAL;
+		}
 	default:
 		return -EINVAL;
 	}
@@ -948,6 +1025,16 @@ static int vcnl4040_read_avail(struct iio_dev *indio_dev,
 		default:
 			return -EINVAL;
 		}
+	case IIO_CHAN_INFO_CALIBBIAS:
+		switch (chan->type) {
+		case IIO_PROXIMITY:
+			*vals = (int *)vcnl4040_ps_calibbias_ua;
+			*length = 2 * ARRAY_SIZE(vcnl4040_ps_calibbias_ua);
+			*type = IIO_VAL_INT_PLUS_MICRO;
+			return IIO_AVAIL_LIST;
+		default:
+			return -EINVAL;
+		}
 	default:
 		return -EINVAL;
 	}
@@ -1721,9 +1808,11 @@ static const struct iio_chan_spec vcnl4040_channels[] = {
 		.type = IIO_PROXIMITY,
 		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW) |
 			BIT(IIO_CHAN_INFO_INT_TIME) |
-			BIT(IIO_CHAN_INFO_OVERSAMPLING_RATIO),
+			BIT(IIO_CHAN_INFO_OVERSAMPLING_RATIO) |
+			BIT(IIO_CHAN_INFO_CALIBBIAS),
 		.info_mask_separate_available = BIT(IIO_CHAN_INFO_INT_TIME) |
-			BIT(IIO_CHAN_INFO_OVERSAMPLING_RATIO),
+			BIT(IIO_CHAN_INFO_OVERSAMPLING_RATIO) |
+			BIT(IIO_CHAN_INFO_CALIBBIAS),
 		.ext_info = vcnl4000_ext_info,
 		.event_spec = vcnl4040_event_spec,
 		.num_event_specs = ARRAY_SIZE(vcnl4040_event_spec),