[PATCH v2 3/5] iio:magnetometer:ak8975: power regulator support

[Gregor Boirie <gregor.boirie@xxxxxxxxxx>]

Add support for an optional regulator which, if found into device-tree,
will power on device at probing time.
The regulator is declared into ak8975 DTS entry as a "vdd-supply" property.

Signed-off-by: Gregor Boirie <gregor.boirie@xxxxxxxxxx>
---
 .../devicetree/bindings/iio/magnetometer/ak8975.txt      |  2 ++
 drivers/iio/magnetometer/ak8975.c                        | 16 ++++++++++++++++
 2 files changed, 18 insertions(+)

diff --git a/Documentation/devicetree/bindings/iio/magnetometer/ak8975.txt b/Documentation/devicetree/bindings/iio/magnetometer/ak8975.txt
index 011679f..34a3206 100644
--- a/Documentation/devicetree/bindings/iio/magnetometer/ak8975.txt
+++ b/Documentation/devicetree/bindings/iio/magnetometer/ak8975.txt
@@ -8,6 +8,7 @@ Required properties:
 Optional properties:
 
   - gpios : should be device tree identifier of the magnetometer DRDY pin
+  - vdd-supply: an optional regulator that needs to be on to provide VDD
 
 Example:
 
@@ -15,4 +16,5 @@ ak8975@0c {
         compatible = "asahi-kasei,ak8975";
         reg = <0x0c>;
         gpios = <&gpj0 7 0>;
+        vdd-supply = <&ldo_3v3_gnss>;
 };
diff --git a/drivers/iio/magnetometer/ak8975.c b/drivers/iio/magnetometer/ak8975.c
index 896b13e3..72c03d9 100644
--- a/drivers/iio/magnetometer/ak8975.c
+++ b/drivers/iio/magnetometer/ak8975.c
@@ -32,6 +32,7 @@
 #include <linux/gpio.h>
 #include <linux/of_gpio.h>
 #include <linux/acpi.h>
+#include <linux/regulator/consumer.h>
 
 #include <linux/iio/iio.h>
 #include <linux/iio/sysfs.h>
@@ -379,8 +380,23 @@ static int ak8975_who_i_am(struct i2c_client *client,
 			   enum asahi_compass_chipset type)
 {
 	u8 wia_val[2];
+	struct regulator *vdd = devm_regulator_get_optional(&client->dev,
+							    "vdd");
 	int ret;
 
+	/* Enable attached regulator if any. */
+	if (!IS_ERR(vdd)) {
+		ret = regulator_enable(vdd);
+		if (ret) {
+			dev_err(&client->dev, "Failed to enable Vdd supply\n");
+			return ret;
+		}
+	} else {
+		ret = PTR_ERR(vdd);
+		if (ret != -ENODEV)
+			return ret;
+	}
+
 	/*
 	 * Signature for each device:
 	 * Device   |  WIA1      |  WIA2
-- 
2.1.4

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