iio: light: us5182d: Add property for choosing default power mode

This chip supports two power modes.
1. "one-shot" mode - the chip activates and executes one complete
conversion loop and then shuts itself down. This is the default mode
chosen for raw reads.
2. "continuous" mode - the chip takes continuous measurements.

Continuous mode is more expensive power-wise but may be more reliable.
Add a property so that if preferred, the default power mode for raw
reads can be set to continuous.
Separate one-shot enabling in a separate function that will be used
depending on the chosen power mode. Also create a function for
powering the chip on and off.

Signed-off-by: Adriana Reus <adriana.reus@intel.com>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

drivers/iio/light/us5182d.c

@@ -99,6 +99,11 @@ enum mode {
 	US5182D_PX_ONLY
 };
 
+enum pmode {
+	US5182D_CONTINUOUS,
+	US5182D_ONESHOT
+};
+
 struct us5182d_data {
 	struct i2c_client *client;
 	struct mutex lock;
@@ -112,6 +117,9 @@ struct us5182d_data {
 	u16 *us5182d_dark_ths;
 
 	u8 opmode;
+	u8 power_mode;
+
+	bool default_continuous;
 };
 
 static IIO_CONST_ATTR(in_illuminance_scale_available,
@@ -130,13 +138,11 @@ static const struct {
 	u8 reg;
 	u8 val;
 } us5182d_regvals[] = {
-	{US5182D_REG_CFG0, (US5182D_CFG0_SHUTDOWN_EN |
-			    US5182D_CFG0_WORD_ENABLE)},
+	{US5182D_REG_CFG0, US5182D_CFG0_WORD_ENABLE},
 	{US5182D_REG_CFG1, US5182D_CFG1_ALS_RES16},
 	{US5182D_REG_CFG2, (US5182D_CFG2_PX_RES16 |
 			    US5182D_CFG2_PXGAIN_DEFAULT)},
 	{US5182D_REG_CFG3, US5182D_CFG3_LED_CURRENT100},
-	{US5182D_REG_MODE_STORE, US5182D_STORE_MODE},
 	{US5182D_REG_CFG4, 0x00},
 };
 
@@ -169,7 +175,7 @@ static int us5182d_get_als(struct us5182d_data *data)
 	return result;
 }
 
-static int us5182d_set_opmode(struct us5182d_data *data, u8 mode)
+static int us5182d_oneshot_en(struct us5182d_data *data)
 {
 	int ret;
 
@@ -183,6 +189,20 @@ static int us5182d_set_opmode(struct us5182d_data *data, u8 mode)
 	 */
 	ret = ret | US5182D_CFG0_ONESHOT_EN;
 
+	return i2c_smbus_write_byte_data(data->client, US5182D_REG_CFG0, ret);
+}
+
+static int us5182d_set_opmode(struct us5182d_data *data, u8 mode)
+{
+	int ret;
+
+	if (mode == data->opmode)
+		return 0;
+
+	ret = i2c_smbus_read_byte_data(data->client, US5182D_REG_CFG0);
+	if (ret < 0)
+		return ret;
+
 	/* update mode */
 	ret = ret & ~US5182D_OPMODE_MASK;
 	ret = ret | (mode << US5182D_OPMODE_SHIFT);
@@ -196,9 +216,6 @@ static int us5182d_set_opmode(struct us5182d_data *data, u8 mode)
 	if (ret < 0)
 		return ret;
 
-	if (mode == data->opmode)
-		return 0;
-
 	ret = i2c_smbus_write_byte_data(data->client, US5182D_REG_MODE_STORE,
 					US5182D_STORE_MODE);
 	if (ret < 0)
@@ -210,6 +227,23 @@ static int us5182d_set_opmode(struct us5182d_data *data, u8 mode)
 	return 0;
 }
 
+static int us5182d_shutdown_en(struct us5182d_data *data, u8 state)
+{
+	int ret;
+
+	if (data->power_mode == US5182D_ONESHOT)
+		return 0;
+
+	ret = i2c_smbus_read_byte_data(data->client, US5182D_REG_CFG0);
+	if (ret < 0)
+		return ret;
+
+	ret = ret & ~US5182D_CFG0_SHUTDOWN_EN;
+	ret = ret | state;
+
+	return i2c_smbus_write_byte_data(data->client, US5182D_REG_CFG0, ret);
+}
+
 static int us5182d_read_raw(struct iio_dev *indio_dev,
 			    struct iio_chan_spec const *chan, int *val,
 			    int *val2, long mask)
@@ -222,6 +256,11 @@ static int us5182d_read_raw(struct iio_dev *indio_dev,
 		switch (chan->type) {
 		case IIO_LIGHT:
 			mutex_lock(&data->lock);
+			if (data->power_mode == US5182D_ONESHOT) {
+				ret = us5182d_oneshot_en(data);
+				if (ret < 0)
+					goto out_err;
+			}
 			ret = us5182d_set_opmode(data, US5182D_OPMODE_ALS);
 			if (ret < 0)
 				goto out_err;
@@ -234,6 +273,11 @@ static int us5182d_read_raw(struct iio_dev *indio_dev,
 			return IIO_VAL_INT;
 		case IIO_PROXIMITY:
 			mutex_lock(&data->lock);
+			if (data->power_mode == US5182D_ONESHOT) {
+				ret = us5182d_oneshot_en(data);
+				if (ret < 0)
+					goto out_err;
+			}
 			ret = us5182d_set_opmode(data, US5182D_OPMODE_PX);
 			if (ret < 0)
 				goto out_err;
@@ -368,6 +412,7 @@ static int us5182d_init(struct iio_dev *indio_dev)
 		return ret;
 
 	data->opmode = 0;
+	data->power_mode = US5182D_CONTINUOUS;
 	for (i = 0; i < ARRAY_SIZE(us5182d_regvals); i++) {
 		ret = i2c_smbus_write_byte_data(data->client,
 						us5182d_regvals[i].reg,
@@ -376,7 +421,15 @@ static int us5182d_init(struct iio_dev *indio_dev)
 			return ret;
 	}
 
-	return 0;
+	if (!data->default_continuous) {
+		ret = us5182d_shutdown_en(data, US5182D_CFG0_SHUTDOWN_EN);
+		if (ret < 0)
+			return ret;
+		data->power_mode = US5182D_ONESHOT;
+	}
+
+
+	return ret;
 }
 
 static void us5182d_get_platform_data(struct iio_dev *indio_dev)
@@ -399,6 +452,8 @@ static void us5182d_get_platform_data(struct iio_dev *indio_dev)
 				    "upisemi,lower-dark-gain",
 				    &data->lower_dark_gain))
 		data->lower_dark_gain = US5182D_REG_AUTO_LDARK_GAIN_DEFAULT;
+	data->default_continuous = device_property_read_bool(&data->client->dev,
+							     "upisemi,continuous");
 }
 
 static int  us5182d_dark_gain_config(struct iio_dev *indio_dev)
@@ -464,16 +519,27 @@ static int us5182d_probe(struct i2c_client *client,
 
 	ret = us5182d_dark_gain_config(indio_dev);
 	if (ret < 0)
-		return ret;
+		goto out_err;
+
+	ret = iio_device_register(indio_dev);
+	if (ret < 0)
+		goto out_err;
+
+	return 0;
+
+out_err:
+	us5182d_shutdown_en(data, US5182D_CFG0_SHUTDOWN_EN);
+	return ret;
 
-	return iio_device_register(indio_dev);
 }
 
 static int us5182d_remove(struct i2c_client *client)
 {
+	struct us5182d_data *data = iio_priv(i2c_get_clientdata(client));
+
 	iio_device_unregister(i2c_get_clientdata(client));
-	return i2c_smbus_write_byte_data(client, US5182D_REG_CFG0,
-					 US5182D_CFG0_SHUTDOWN_EN);
+
+	return us5182d_shutdown_en(data, US5182D_CFG0_SHUTDOWN_EN);
 }
 
 static const struct acpi_device_id us5182d_acpi_match[] = {