The accelerometer's power supply could be controlled by regulator
on some platforms, such as i.MX6Q-SABRESD board, the mma8451's
power supply is controlled by a GPIO fixed regulator, need to make
sure the regulator is enabled before any communication with mma8451,
this patch adds optional vcc regulator operation support.

Signed-off-by: Anson Huang <anson.hu...@nxp.com>
---
 drivers/iio/accel/mma8452.c | 88 +++++++++++++++++++++++++++++++++++++++++++--
 1 file changed, 86 insertions(+), 2 deletions(-)

diff --git a/drivers/iio/accel/mma8452.c b/drivers/iio/accel/mma8452.c
index 421a0a8..8f6123f 100644
--- a/drivers/iio/accel/mma8452.c
+++ b/drivers/iio/accel/mma8452.c
@@ -31,6 +31,7 @@
 #include <linux/of_device.h>
 #include <linux/of_irq.h>
 #include <linux/pm_runtime.h>
+#include <linux/regulator/consumer.h>
 
 #define MMA8452_STATUS                         0x00
 #define  MMA8452_STATUS_DRDY                   (BIT(2) | BIT(1) | BIT(0))
@@ -107,6 +108,7 @@ struct mma8452_data {
        u8 data_cfg;
        const struct mma_chip_info *chip_info;
        int sleep_val;
+       struct regulator *vcc_reg;
 };
 
  /**
@@ -1533,6 +1535,14 @@ static int mma8452_probe(struct i2c_client *client,
        data->client = client;
        mutex_init(&data->lock);
        data->chip_info = match->data;
+       data->vcc_reg = devm_regulator_get_optional(&client->dev, "vcc");
+       if (!IS_ERR(data->vcc_reg)) {
+               ret = regulator_enable(data->vcc_reg);
+               if (ret) {
+                       dev_err(&client->dev, "failed to enable VCC 
regulator\n");
+                       return ret;
+               }
+       }
 
        ret = i2c_smbus_read_byte_data(client, MMA8452_WHO_AM_I);
        if (ret < 0)
@@ -1667,6 +1677,8 @@ static int mma8452_probe(struct i2c_client *client,
 static int mma8452_remove(struct i2c_client *client)
 {
        struct iio_dev *indio_dev = i2c_get_clientdata(client);
+       struct mma8452_data *data = iio_priv(indio_dev);
+       int ret;
 
        iio_device_unregister(indio_dev);
 
@@ -1678,6 +1690,14 @@ static int mma8452_remove(struct i2c_client *client)
        mma8452_trigger_cleanup(indio_dev);
        mma8452_standby(iio_priv(indio_dev));
 
+       if (!IS_ERR(data->vcc_reg)) {
+               ret = regulator_disable(data->vcc_reg);
+               if (ret) {
+                       dev_err(&client->dev, "failed to disable VCC 
regulator\n");
+                       return ret;
+               }
+       }
+
        return 0;
 }
 
@@ -1696,6 +1716,14 @@ static int mma8452_runtime_suspend(struct device *dev)
                return -EAGAIN;
        }
 
+       if (!IS_ERR(data->vcc_reg)) {
+               ret = regulator_disable(data->vcc_reg);
+               if (ret) {
+                       dev_err(dev, "failed to disable VCC regulator\n");
+                       return ret;
+               }
+       }
+
        return 0;
 }
 
@@ -1705,6 +1733,14 @@ static int mma8452_runtime_resume(struct device *dev)
        struct mma8452_data *data = iio_priv(indio_dev);
        int ret, sleep_val;
 
+       if (!IS_ERR(data->vcc_reg)) {
+               ret = regulator_enable(data->vcc_reg);
+               if (ret) {
+                       dev_err(dev, "failed to enable VCC regulator\n");
+                       return ret;
+               }
+       }
+
        ret = mma8452_active(data);
        if (ret < 0)
                return ret;
@@ -1723,14 +1759,62 @@ static int mma8452_runtime_resume(struct device *dev)
 #ifdef CONFIG_PM_SLEEP
 static int mma8452_suspend(struct device *dev)
 {
-       return mma8452_standby(iio_priv(i2c_get_clientdata(
+       struct iio_dev *indio_dev = i2c_get_clientdata(to_i2c_client(dev));
+       struct mma8452_data *data = iio_priv(indio_dev);
+       int ret;
+
+       if (!IS_ERR(data->vcc_reg)) {
+               ret = regulator_enable(data->vcc_reg);
+               if (ret) {
+                       dev_err(dev, "failed to enable VCC regulator\n");
+                       return ret;
+               }
+       }
+
+       ret = mma8452_standby(iio_priv(i2c_get_clientdata(
                to_i2c_client(dev))));
+       if (ret)
+               return ret;
+
+       if (!IS_ERR(data->vcc_reg)) {
+               ret = regulator_disable(data->vcc_reg);
+               if (ret) {
+                       dev_err(dev, "failed to disable VCC regulator\n");
+                       return ret;
+               }
+       }
+
+       return 0;
 }
 
 static int mma8452_resume(struct device *dev)
 {
-       return mma8452_active(iio_priv(i2c_get_clientdata(
+       struct iio_dev *indio_dev = i2c_get_clientdata(to_i2c_client(dev));
+       struct mma8452_data *data = iio_priv(indio_dev);
+       int ret;
+
+       if (!IS_ERR(data->vcc_reg)) {
+               ret = regulator_enable(data->vcc_reg);
+               if (ret) {
+                       dev_err(dev, "failed to enable VCC regulator\n");
+                       return ret;
+               }
+       }
+
+       ret = mma8452_active(iio_priv(i2c_get_clientdata(
                to_i2c_client(dev))));
+       if (ret)
+               return ret;
+
+       if (!IS_ERR(data->vcc_reg)) {
+               ret = regulator_disable(data->vcc_reg);
+               if (ret) {
+                       dev_err(dev, "failed to disable VCC regulator\n");
+                       return ret;
+               }
+       }
+
+       return 0;
 }
 #endif
 
-- 
2.7.4

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