media: hi556: Add support for avdd regulator

On some ACPI platforms, such as Chromebooks the ACPI methods to
change the power-state (_PS0 and _PS3) fully take care of powering
on/off the sensor.

On other ACPI platforms, such as e.g. various HP models with IPU6 +
hi556 sensor, the sensor driver must control the avdd regulator itself.

Add support for having the driver control the sensor's avdd regulator.
Note this relies on the regulator-core providing a dummy regulator
(which it does by default) on platforms where Linux is not aware of
the avdd regulator.
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Sakari Ailus <sakari.ailus@linux.intel.com>
Signed-off-by: Hans Verkuil <hverkuil-cisco@xs4all.nl>

drivers/media/i2c/hi556.c

@@ -9,6 +9,7 @@
 #include <linux/i2c.h>
 #include <linux/module.h>
 #include <linux/pm_runtime.h>
+#include <linux/regulator/consumer.h>
 #include <media/v4l2-ctrls.h>
 #include <media/v4l2-device.h>
 #include <media/v4l2-fwnode.h>
@@ -638,6 +639,7 @@ struct hi556 {
 	/* GPIOs, clocks, etc. */
 	struct gpio_desc *reset_gpio;
 	struct clk *clk;
+	struct regulator *avdd;
 
 	/* Current mode */
 	const struct hi556_mode *cur_mode;
@@ -1286,8 +1288,17 @@ static int hi556_suspend(struct device *dev)
 {
 	struct v4l2_subdev *sd = dev_get_drvdata(dev);
 	struct hi556 *hi556 = to_hi556(sd);
+	int ret;
 
 	gpiod_set_value_cansleep(hi556->reset_gpio, 1);
+
+	ret = regulator_disable(hi556->avdd);
+	if (ret) {
+		dev_err(dev, "failed to disable avdd: %d\n", ret);
+		gpiod_set_value_cansleep(hi556->reset_gpio, 0);
+		return ret;
+	}
+
 	clk_disable_unprepare(hi556->clk);
 	return 0;
 }
@@ -1302,6 +1313,13 @@ static int hi556_resume(struct device *dev)
 	if (ret)
 		return ret;
 
+	ret = regulator_enable(hi556->avdd);
+	if (ret) {
+		dev_err(dev, "failed to enable avdd: %d\n", ret);
+		clk_disable_unprepare(hi556->clk);
+		return ret;
+	}
+
 	gpiod_set_value_cansleep(hi556->reset_gpio, 0);
 	usleep_range(5000, 5500);
 	return 0;
@@ -1337,6 +1355,12 @@ static int hi556_probe(struct i2c_client *client)
 		return dev_err_probe(&client->dev, PTR_ERR(hi556->clk),
 				     "failed to get clock\n");
 
+	/* The regulator core will provide a "dummy" regulator if necessary */
+	hi556->avdd = devm_regulator_get(&client->dev, "avdd");
+	if (IS_ERR(hi556->avdd))
+		return dev_err_probe(&client->dev, PTR_ERR(hi556->avdd),
+				     "failed to get avdd regulator\n");
+
 	full_power = acpi_dev_state_d0(&client->dev);
 	if (full_power) {
 		/* Ensure non ACPI managed resources are enabled */