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>

1 files changed, 16 insertions, 0 deletions

diff --git a/drivers/iio/magnetometer/ak8975.c b/drivers/iio/magnetometer/ak8975.c
index 896b13e39dae..72c03d9fbeb2 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