iio: accel: bmc150-accel: Add rudimentary regulator support

These Bosch accelerometers have two supplies, VDD and VDDIO.
Add some rudimentary support to obtain and enable these
regulators during probe() and disable them during remove()
or on the errorpath.

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

drivers/iio/accel/bmc150-accel-core.c

···
 #include <linux/iio/trigger_consumer.h>
 #include <linux/iio/triggered_buffer.h>
 #include <linux/regmap.h>
+#include <linux/regulator/consumer.h>
 
 #include "bmc150-accel.h"
 
···
 
 struct bmc150_accel_data {
 	struct regmap *regmap;
+	struct regulator_bulk_data regulators[2];
 	int irq;
 	struct bmc150_accel_interrupt interrupts[BMC150_ACCEL_INTERRUPTS];
 	struct bmc150_accel_trigger triggers[BMC150_ACCEL_TRIGGERS];
···
 				     &data->orientation);
 	if (ret)
 		return ret;
+	/*
+	 * VDD   is the analog and digital domain voltage supply
+	 * VDDIO is the digital I/O voltage supply
+	 */
+	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 = regulator_bulk_enable(ARRAY_SIZE(data->regulators),
+				    data->regulators);
+	if (ret) {
+		dev_err(dev, "failed to enable regulators: %d\n", ret);
+		return ret;
+	}
+	/*
+	 * 2ms or 3ms power-on time according to datasheets, let's better
+	 * be safe than sorry and set this delay to 5ms.
+	 */
+	msleep(5);
 
 	ret = bmc150_accel_chip_init(data);
 	if (ret < 0)
-		return ret;
+		goto err_disable_regulators;
 
 	mutex_init(&data->mutex);
 
···
 					     fifo_attrs);
 	if (ret < 0) {
 		dev_err(dev, "Failed: iio triggered buffer setup\n");
-		return ret;
+		goto err_disable_regulators;
 	}
 
 	if (data->irq > 0) {
···
 	bmc150_accel_unregister_triggers(data, BMC150_ACCEL_TRIGGERS - 1);
 err_buffer_cleanup:
 	iio_triggered_buffer_cleanup(indio_dev);
+err_disable_regulators:
+	regulator_bulk_disable(ARRAY_SIZE(data->regulators),
+			       data->regulators);
 
 	return ret;
 }
···
 	mutex_lock(&data->mutex);
 	bmc150_accel_set_mode(data, BMC150_ACCEL_SLEEP_MODE_DEEP_SUSPEND, 0);
 	mutex_unlock(&data->mutex);
+
+	regulator_bulk_disable(ARRAY_SIZE(data->regulators),
+			       data->regulators);
 
 	return 0;
 }