iio: pressure: bmp280: support supply regulators

The BMP085/BMP180/BMP280 is supplied with two power sources:
VDDA (analog power) and VDDD (digital power). As these may come
from regulators (as on the APQ8060 Dragonboard) we need the driver
to attempt to fetch and enable these regulators.

We FAIL if we cannot: boards should either define:
- Proper regulators if present
- Define fixed regulators if power is hardwired to the component
- Rely on dummy regulators (will be present on all DT systems and
  any boardfile system that calls regulator_has_full_constraints().

Cc: Mark Brown <broonie@kernel.org>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

drivers/iio/pressure/bmp280.c

@@ -24,6 +24,7 @@
 #include <linux/iio/iio.h>
 #include <linux/iio/sysfs.h>
 #include <linux/gpio/consumer.h>
+#include <linux/regulator/consumer.h>
 
 /* BMP280 specific registers */
 #define BMP280_REG_HUMIDITY_LSB		0xFE
@@ -124,6 +125,9 @@ struct bmp280_data {
 	struct mutex lock;
 	struct regmap *regmap;
 	const struct bmp280_chip_info *chip_info;
+	struct regulator *vddd;
+	struct regulator *vdda;
+	unsigned int start_up_time; /* in milliseconds */
 
 	/* log of base 2 of oversampling rate */
 	u8 oversampling_press;
@@ -1047,12 +1051,14 @@ static int bmp280_probe(struct i2c_client *client,
 		data->chip_info = &bmp180_chip_info;
 		data->oversampling_press = ilog2(8);
 		data->oversampling_temp = ilog2(1);
+		data->start_up_time = 10;
 		break;
 	case BMP280_CHIP_ID:
 		indio_dev->num_channels = 2;
 		data->chip_info = &bmp280_chip_info;
 		data->oversampling_press = ilog2(16);
 		data->oversampling_temp = ilog2(2);
+		data->start_up_time = 2;
 		break;
 	case BME280_CHIP_ID:
 		indio_dev->num_channels = 3;
@@ -1060,11 +1066,37 @@ static int bmp280_probe(struct i2c_client *client,
 		data->oversampling_press = ilog2(16);
 		data->oversampling_humid = ilog2(16);
 		data->oversampling_temp = ilog2(2);
+		data->start_up_time = 2;
 		break;
 	default:
 		return -EINVAL;
 	}
 
+	/* Bring up regulators */
+	data->vddd = devm_regulator_get(&client->dev, "vddd");
+	if (IS_ERR(data->vddd)) {
+		dev_err(&client->dev, "failed to get VDDD regulator\n");
+		return PTR_ERR(data->vddd);
+	}
+	ret = regulator_enable(data->vddd);
+	if (ret) {
+		dev_err(&client->dev, "failed to enable VDDD regulator\n");
+		return ret;
+	}
+	data->vdda = devm_regulator_get(&client->dev, "vdda");
+	if (IS_ERR(data->vdda)) {
+		dev_err(&client->dev, "failed to get VDDA regulator\n");
+		ret = PTR_ERR(data->vddd);
+		goto out_disable_vddd;
+	}
+	ret = regulator_enable(data->vdda);
+	if (ret) {
+		dev_err(&client->dev, "failed to enable VDDA regulator\n");
+		goto out_disable_vddd;
+	}
+	/* Wait to make sure we started up properly */
+	mdelay(data->start_up_time);
+
 	/* Bring chip out of reset if there is an assigned GPIO line */
 	gpiod = devm_gpiod_get(&client->dev, "reset", GPIOD_OUT_HIGH);
 	/* Deassert the signal */
@@ -1077,7 +1109,8 @@ static int bmp280_probe(struct i2c_client *client,
 					data->chip_info->regmap_config);
 	if (IS_ERR(data->regmap)) {
 		dev_err(&client->dev, "failed to allocate register map\n");
-		return PTR_ERR(data->regmap);
+		ret = PTR_ERR(data->regmap);
+		goto out_disable_vdda;
 	}
 
 	ret = regmap_read(data->regmap, BMP280_REG_ID, &chip_id);
@@ -1086,14 +1119,38 @@ static int bmp280_probe(struct i2c_client *client,
 	if (chip_id != id->driver_data) {
 		dev_err(&client->dev, "bad chip id.  expected %lx got %x\n",
 			id->driver_data, chip_id);
-		return -EINVAL;
+		ret = -EINVAL;
+		goto out_disable_vdda;
 	}
 
 	ret = data->chip_info->chip_config(data);
 	if (ret < 0)
+		goto out_disable_vdda;
+
+	i2c_set_clientdata(client, indio_dev);
+
+	ret = iio_device_register(indio_dev);
+	if (ret)
+		goto out_disable_vdda;
+
+	return 0;
+
+out_disable_vdda:
+	regulator_disable(data->vdda);
+out_disable_vddd:
+	regulator_disable(data->vddd);
 	return ret;
+}
 
-	return devm_iio_device_register(&client->dev, indio_dev);
+static int bmp280_remove(struct i2c_client *client)
+{
+	struct iio_dev *indio_dev = i2c_get_clientdata(client);
+	struct bmp280_data *data = iio_priv(indio_dev);
+
+	iio_device_unregister(indio_dev);
+	regulator_disable(data->vdda);
+	regulator_disable(data->vddd);
+	return 0;
 }
 
 static const struct acpi_device_id bmp280_acpi_match[] = {
@@ -1134,6 +1191,7 @@ static struct i2c_driver bmp280_driver = {
 		.of_match_table = of_match_ptr(bmp280_of_match),
 	},
 	.probe		= bmp280_probe,
+	.remove		= bmp280_remove,
 	.id_table	= bmp280_id,
 };
 module_i2c_driver(bmp280_driver);