[PATCH v3 2/5] max44000: Initial support for proximity reading

[Crestez Dan Leonard <leonard.crestez@intel.com>]

The proximity sensor relies on sending pulses to an external IR led and
it is disabled by default on powerup. The driver will enable it with a
default power setting.

Signed-off-by: Crestez Dan Leonard <leonard.crestez@intel.com>
---
 drivers/iio/light/max44000.c | 45 ++++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 43 insertions(+), 2 deletions(-)

diff --git a/drivers/iio/light/max44000.c b/drivers/iio/light/max44000.c
index 5ed7934..dc63de2 100644
--- a/drivers/iio/light/max44000.c
+++ b/drivers/iio/light/max44000.c
@@ -59,6 +59,11 @@
  */
 #define MAX44000_REG_CFG_RX_DEFAULT 0xf0
 
+/* REG_TX bits */
+#define MAX44000_LED_CURRENT_MASK	0xf
+#define MAX44000_LED_CURRENT_MAX	11
+#define MAX44000_LED_CURRENT_DEFAULT	6
+
 #define MAX44000_ALSDATA_OVERFLOW	0x4000
 
 struct max44000_data {
@@ -75,6 +80,11 @@ static const struct iio_chan_spec max44000_channels[] = {
 		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
 		.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),
 	},
+	{
+		.type = IIO_PROXIMITY,
+		.info_mask_separate = BIT(IIO_CHAN_INFO_RAW),
+		.info_mask_shared_by_type = BIT(IIO_CHAN_INFO_SCALE),
+	},
 };
 
 static int max44000_read_alsval(struct max44000_data *data)
@@ -104,11 +114,23 @@ static int max44000_read_alsval(struct max44000_data *data)
 	return regval;
 }
 
+static int max44000_write_led_current_raw(struct max44000_data *data, int val)
+{
+	/* Maybe we should clamp the value instead? */
+	if (val < 0 || val > MAX44000_LED_CURRENT_MAX)
+		return -ERANGE;
+	if (val >= 8)
+		val += 4;
+	return regmap_write_bits(data->regmap, MAX44000_REG_CFG_TX,
+				 MAX44000_LED_CURRENT_MASK, val);
+}
+
 static int max44000_read_raw(struct iio_dev *indio_dev,
 			     struct iio_chan_spec const *chan,
 			     int *val, int *val2, long mask)
 {
 	struct max44000_data *data = iio_priv(indio_dev);
+	unsigned int regval;
 	int ret;
 
 	switch (mask) {
@@ -123,6 +145,15 @@ static int max44000_read_raw(struct iio_dev *indio_dev,
 			*val = ret;
 			return IIO_VAL_INT;
 
+		case IIO_PROXIMITY:
+			mutex_lock(&data->lock);
+			ret = regmap_read(data->regmap, MAX44000_REG_PRX_DATA, &regval);
+			mutex_unlock(&data->lock);
+			if (ret < 0)
+				return ret;
+			*val = regval;
+			return IIO_VAL_INT;
+
 		default:
 			return -EINVAL;
 		}
@@ -266,8 +297,18 @@ static int max44000_probe(struct i2c_client *client,
 		return ret;
 	}
 
-	/* Reset CFG bits to ALS-only mode and no interrupts */
-	reg = MAX44000_CFG_TRIM | MAX44000_CFG_MODE_ALS_GIR;
+	/*
+	 * By default the LED pulse used for the proximity sensor is disabled.
+	 * Set a middle value so that we get some sort of valid data by default.
+	 */
+	ret = max44000_write_led_current_raw(data, MAX44000_LED_CURRENT_DEFAULT);
+	if (ret < 0) {
+		dev_err(&client->dev, "failed to write init config: %d\n", ret);
+		return ret;
+	}
+
+	/* Reset CFG bits to ALS_PRX mode which allows easy reading of both values. */
+	reg = MAX44000_CFG_TRIM | MAX44000_CFG_MODE_ALS_PRX;
 	ret = regmap_write(data->regmap, MAX44000_REG_CFG_MAIN, reg);
 	if (ret < 0) {
 		dev_err(&client->dev, "failed to write init config: %d\n", ret);
-- 
2.5.5