iio:magnetometer:ak8975: power regulator support

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@parrot.com>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

diff --git a/Documentation/devicetree/bindings/iio/magnetometer/ak8975.txt b/Documentation/devicetree/bindings/iio/magnetometer/ak8975.txt
index 011679f..34a3206 100644 (file)
--- 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 896b13e..72c03d9 100644 (file)
--- 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