drm: Convert drm class driver from legacy pm ops to dev_pm_ops

Convert drivers/gpu/drm class to use dev_pm_ops for power management and
remove Legacy PM ops hooks. With this change, drm class registers
suspend/resume callbacks via class->pm (dev_pm_ops) instead of Legacy
class->suspend/resume. When __device_suspend() runs call-backs, it will
find class->pm ops for the drm class.

drm_class_suspend() hook calls driver legacy ops with the state information.
e.g: drm_class_suspend() calls into driver suspend routines
via drm_dev->driver->suspend(drm_dev, state).

Once drm_class_suspend() is converted to dev_pm_ops, it will no longer
have access to pm_transition which it has to pass into driver legacy
suspend calls. A new freeze and suspend hooks are added to address the not
having access to the state information. The new freeze and suspend hooks
simply call __drm_class_suspend() with the appropriate pm state information.
__drm_class_suspend() is the original suspend hook with a new name.

Signed-off-by: Shuah Khan <[e-mail]>
Signed-off-by: Dave Airlie <[e-mail]>

drivers/gpu/drm/drm_sysfs.c

···
 };
 
 /**
- * drm_class_suspend - DRM class suspend hook
+ * __drm_class_suspend - internal DRM class suspend routine
  * @dev: Linux device to suspend
  * @state: power state to enter
  *
  * Just figures out what the actual struct drm_device associated with
  * @dev is and calls its suspend hook, if present.
  */
-static int drm_class_suspend(struct device *dev, pm_message_t state)
+static int __drm_class_suspend(struct device *dev, pm_message_t state)
 {
 	if (dev->type == &drm_sysfs_device_minor) {
 		struct drm_minor *drm_minor = to_drm_minor(dev);
···
 			return drm_dev->driver->suspend(drm_dev, state);
 	}
 	return 0;
+}
+
+/**
+ * drm_class_suspend - internal DRM class suspend hook. Simply calls
+ * __drm_class_suspend() with the correct pm state.
+ * @dev: Linux device to suspend
+ */
+static int drm_class_suspend(struct device *dev)
+{
+	return __drm_class_suspend(dev, PMSG_SUSPEND);
+}
+
+/**
+ * drm_class_freeze - internal DRM class freeze hook. Simply calls
+ * __drm_class_suspend() with the correct pm state.
+ * @dev: Linux device to freeze
+ */
+static int drm_class_freeze(struct device *dev)
+{
+	return __drm_class_suspend(dev, PMSG_FREEZE);
 }
 
 /**
···
 	}
 	return 0;
 }
+
+static const struct dev_pm_ops drm_class_dev_pm_ops = {
+	.suspend	= drm_class_suspend,
+	.resume		= drm_class_resume,
+	.freeze		= drm_class_freeze,
+};
 
 static char *drm_devnode(struct device *dev, umode_t *mode)
 {
···
 		goto err_out;
 	}
 
-	class->suspend = drm_class_suspend;
-	class->resume = drm_class_resume;
+	class->pm = &drm_class_dev_pm_ops;
 
 	err = class_create_file(class, &class_attr_version.attr);
 	if (err)