iio: magnetometer: bmc150: Add rudimentary regulator support

BMC150 needs VDD and VDDIO regulators that might need to be explicitly
enabled. Add some rudimentary support to obtain and enable these
regulators during probe() and disable them during remove()
or on the error path.
Reviewed-by: NLinus Walleij <linus.walleij@linaro.org>
Signed-off-by: NStephan Gerhold <stephan@gerhold.net>
Link: https://lore.kernel.org/r/20210109152327.512538-2-stephan@gerhold.netSigned-off-by: NJonathan Cameron <Jonathan.Cameron@huawei.com>

drivers/iio/magnetometer/bmc150_magn.c

@@ -25,6 +25,7 @@
 #include <linux/iio/trigger_consumer.h>
 #include <linux/iio/triggered_buffer.h>
 #include <linux/regmap.h>
+#include <linux/regulator/consumer.h>
 
 #include "bmc150_magn.h"
 
@@ -135,6 +136,7 @@ struct bmc150_magn_data {
 	 */
 	struct mutex mutex;
 	struct regmap *regmap;
+	struct regulator_bulk_data regulators[2];
 	struct iio_mount_matrix orientation;
 	/* 4 x 32 bits for x, y z, 4 bytes align, 64 bits timestamp */
 	s32 buffer[6];
@@ -692,12 +694,24 @@ static int bmc150_magn_init(struct bmc150_magn_data *data)
 	int ret, chip_id;
 	struct bmc150_magn_preset preset;
 
+	ret = regulator_bulk_enable(ARRAY_SIZE(data->regulators),
+				    data->regulators);
+	if (ret < 0) {
+		dev_err(data->dev, "Failed to enable regulators: %d\n", ret);
+		return ret;
+	}
+	/*
+	 * 3ms power-on time according to datasheet, let's better
+	 * be safe than sorry and set this delay to 5ms.
+	 */
+	msleep(5);
+
 	ret = bmc150_magn_set_power_mode(data, BMC150_MAGN_POWER_MODE_SUSPEND,
 					 false);
 	if (ret < 0) {
 		dev_err(data->dev,
 			"Failed to bring up device from suspend mode\n");
-		return ret;
+		goto err_regulator_disable;
 	}
 
 	ret = regmap_read(data->regmap, BMC150_MAGN_REG_CHIP_ID, &chip_id);
@@ -752,6 +766,8 @@ static int bmc150_magn_init(struct bmc150_magn_data *data)
 
 err_poweroff:
 	bmc150_magn_set_power_mode(data, BMC150_MAGN_POWER_MODE_SUSPEND, true);
+err_regulator_disable:
+	regulator_bulk_disable(ARRAY_SIZE(data->regulators), data->regulators);
 	return ret;
 }
 
@@ -867,6 +883,13 @@ int bmc150_magn_probe(struct device *dev, struct regmap *regmap,
 	data->irq = irq;
 	data->dev = dev;
 
+	data->regulators[0].supply = "vdd";
+	data->regulators[1].supply = "vddio";
+	ret = devm_regulator_bulk_get(dev, ARRAY_SIZE(data->regulators),
+				      data->regulators);
+	if (ret)
+		return dev_err_probe(dev, ret, "failed to get regulators\n");
+
 	ret = iio_read_mount_matrix(dev, "mount-matrix",
 				&data->orientation);
 	if (ret)
@@ -984,6 +1007,7 @@ int bmc150_magn_remove(struct device *dev)
 	bmc150_magn_set_power_mode(data, BMC150_MAGN_POWER_MODE_SUSPEND, true);
 	mutex_unlock(&data->mutex);
 
+	regulator_bulk_disable(ARRAY_SIZE(data->regulators), data->regulators);
 	return 0;
 }
 EXPORT_SYMBOL(bmc150_magn_remove);