#include <linux/gpio.h>
 #include <linux/gpio/consumer.h>
 #include <linux/module.h>
+#include <linux/pm_runtime.h>
 #include <linux/regulator/consumer.h>
 #include <linux/slab.h>
 #include <linux/smiapp.h>
  * Power management
  */
 
-static int smiapp_power_on(struct smiapp_sensor *sensor)
+static int smiapp_power_on(struct device *dev)
 {
-       struct i2c_client *client = v4l2_get_subdevdata(&sensor->src->sd);
+       struct i2c_client *client = to_i2c_client(dev);
+       struct v4l2_subdev *subdev = i2c_get_clientdata(client);
+       struct smiapp_subdev *ssd = to_smiapp_subdev(subdev);
+       /*
+        * The sub-device related to the I2C device is always the
+        * source one, i.e. ssds[0].
+        */
+       struct smiapp_sensor *sensor =
+               container_of(ssd, struct smiapp_sensor, ssds[0]);
        unsigned int sleep;
        int rval;
 
        return 0;
 
 out_cci_addr_fail:
+
        gpiod_set_value(sensor->xshutdown, 0);
        clk_disable_unprepare(sensor->ext_clk);
 
 out_xclk_fail:
        regulator_disable(sensor->vana);
+
        return rval;
 }
 
-static void smiapp_power_off(struct smiapp_sensor *sensor)
+static int smiapp_power_off(struct device *dev)
 {
+       struct i2c_client *client = to_i2c_client(dev);
+       struct v4l2_subdev *subdev = i2c_get_clientdata(client);
+       struct smiapp_subdev *ssd = to_smiapp_subdev(subdev);
+       struct smiapp_sensor *sensor =
+               container_of(ssd, struct smiapp_sensor, ssds[0]);
+
        /*
         * Currently power/clock to lens are enable/disabled separately
         * but they are essentially the same signals. So if the sensor is
        usleep_range(5000, 5000);
        regulator_disable(sensor->vana);
        sensor->streaming = false;
+
+       return 0;
 }
 
 static int smiapp_set_power(struct v4l2_subdev *subdev, int on)
 {
-       struct smiapp_sensor *sensor = to_smiapp_sensor(subdev);
-       int ret = 0;
+       int rval = 0;
 
-       mutex_lock(&sensor->power_mutex);
+       if (on) {
+               rval = pm_runtime_get_sync(subdev->dev);
+               if (rval >= 0)
+                       return 0;
 
-       if (on && !sensor->power_count) {
-               /* Power on and perform initialisation. */
-               ret = smiapp_power_on(sensor);
-               if (ret < 0)
-                       goto out;
-       } else if (!on && sensor->power_count == 1) {
-               smiapp_power_off(sensor);
+               if (rval != -EBUSY && rval != -EAGAIN)
+                       pm_runtime_set_active(subdev->dev);
        }
 
-       /* Update the power count. */
-       sensor->power_count += on ? 1 : -1;
-       WARN_ON(sensor->power_count < 0);
+       pm_runtime_put(subdev->dev);
 
-out:
-       mutex_unlock(&sensor->power_mutex);
-       return ret;
+       return rval;
 }
 
 /* -----------------------------------------------------------------------------
                return -EBUSY;
 
        if (!sensor->nvm_size) {
+               int rval;
+
                /* NVM not read yet - read it now */
                sensor->nvm_size = sensor->hwcfg->nvm_size;
-               if (smiapp_set_power(subdev, 1) < 0)
+
+               rval = pm_runtime_get_sync(&client->dev);
+               if (rval < 0) {
+                       if (rval != -EBUSY && rval != -EAGAIN)
+                               pm_runtime_set_active(&client->dev);
+                       pm_runtime_put(&client->dev);
                        return -ENODEV;
+               }
+
                if (smiapp_read_nvm(sensor, sensor->nvm)) {
                        dev_err(&client->dev, "nvm read failed\n");
                        return -ENODEV;
                }
-               smiapp_set_power(subdev, 0);
+
+               pm_runtime_put(&client->dev);
        }
        /*
         * NVM is still way below a PAGE_SIZE, so we can safely
        struct smiapp_subdev *ssd = to_smiapp_subdev(sd);
        struct smiapp_sensor *sensor = ssd->sensor;
        unsigned int i;
+       int rval;
 
        mutex_lock(&sensor->mutex);
 
 
        mutex_unlock(&sensor->mutex);
 
-       return smiapp_set_power(sd, 1);
+       rval = pm_runtime_get_sync(sd->dev);
+       if (rval >= 0)
+               return 0;
+
+       if (rval != -EBUSY && rval != -EAGAIN)
+               pm_runtime_set_active(sd->dev);
+       pm_runtime_put(sd->dev);
+
+       return rval;
 }
 
 static int smiapp_close(struct v4l2_subdev *sd, struct v4l2_subdev_fh *fh)
 {
-       return smiapp_set_power(sd, 0);
+       pm_runtime_put(sd->dev);
+
+       return 0;
 }
 
 static const struct v4l2_subdev_video_ops smiapp_video_ops = {
        struct i2c_client *client = to_i2c_client(dev);
        struct v4l2_subdev *subdev = i2c_get_clientdata(client);
        struct smiapp_sensor *sensor = to_smiapp_sensor(subdev);
-       bool streaming;
+       bool streaming = sensor->streaming;
+       int rval;
 
-       if (sensor->power_count == 0)
-               return 0;
+       rval = pm_runtime_get_sync(dev);
+       if (rval < 0) {
+               if (rval != -EBUSY && rval != -EAGAIN)
+                       pm_runtime_set_active(&client->dev);
+               pm_runtime_put(dev);
+               return -EAGAIN;
+       }
 
        if (sensor->streaming)
                smiapp_stop_streaming(sensor);
 
-       streaming = sensor->streaming;
-
-       smiapp_power_off(sensor);
-
        /* save state for resume */
        sensor->streaming = streaming;
 
        struct i2c_client *client = to_i2c_client(dev);
        struct v4l2_subdev *subdev = i2c_get_clientdata(client);
        struct smiapp_sensor *sensor = to_smiapp_sensor(subdev);
-       int rval;
-
-       if (sensor->power_count == 0)
-               return 0;
+       int rval = 0;
 
-       rval = smiapp_power_on(sensor);
-       if (rval)
-               return rval;
+       pm_runtime_put(dev);
 
        if (sensor->streaming)
                rval = smiapp_start_streaming(sensor);
 
        sensor->hwcfg = hwcfg;
        mutex_init(&sensor->mutex);
-       mutex_init(&sensor->power_mutex);
        sensor->src = &sensor->ssds[sensor->ssds_used];
 
        v4l2_i2c_subdev_init(&sensor->src->sd, client, &smiapp_ops);
        if (IS_ERR(sensor->xshutdown))
                return PTR_ERR(sensor->xshutdown);
 
-       rval = smiapp_power_on(sensor);
-       if (rval)
-               return -ENODEV;
+       pm_runtime_enable(&client->dev);
+
+       rval = pm_runtime_get_sync(&client->dev);
+       if (rval < 0) {
+               rval = -ENODEV;
+               goto out_power_off;
+       }
 
        rval = smiapp_identify_module(sensor);
        if (rval) {
        sensor->streaming = false;
        sensor->dev_init_done = true;
 
-       smiapp_power_off(sensor);
-
        rval = media_entity_pads_init(&sensor->src->sd.entity, 2,
                                 sensor->src->pads);
        if (rval < 0)
        if (rval < 0)
                goto out_media_entity_cleanup;
 
+       pm_runtime_put(&client->dev);
+
        return 0;
 
 out_media_entity_cleanup:
        smiapp_cleanup(sensor);
 
 out_power_off:
-       smiapp_power_off(sensor);
+       pm_runtime_put(&client->dev);
+       pm_runtime_disable(&client->dev);
+
        return rval;
 }
 
 
        v4l2_async_unregister_subdev(subdev);
 
-       if (sensor->power_count) {
-               gpiod_set_value(sensor->xshutdown, 0);
-               clk_disable_unprepare(sensor->ext_clk);
-               sensor->power_count = 0;
-       }
+       pm_runtime_suspend(&client->dev);
+       pm_runtime_disable(&client->dev);
 
        for (i = 0; i < sensor->ssds_used; i++) {
                v4l2_device_unregister_subdev(&sensor->ssds[i].sd);
 
 static const struct dev_pm_ops smiapp_pm_ops = {
        SET_SYSTEM_SLEEP_PM_OPS(smiapp_suspend, smiapp_resume)
+       SET_RUNTIME_PM_OPS(smiapp_power_off, smiapp_power_on, NULL)
 };
 
 static struct i2c_driver smiapp_i2c_driver = {