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: Linus Walleij <[e-mail]>
Signed-off-by: Stephan Gerhold <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Jonathan Cameron <[e-mail]>

drivers/iio/magnetometer/bmc150_magn.c

···
 #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"
 
···
 	 */
 	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];
···
 	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);
···
 
 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;
 }
 
···
 	data->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);
···
 	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);