drm: Add devm_drm_dev_init()

This adds a resource managed (devres) version of drm_dev_init().

v2: Remove devm_drm_dev_register() since we can't touch hw in devm
    release functions and drivers want to disable hw on driver module
    unload (Daniel Vetter, Greg KH)

Cc: Daniel Vetter <daniel@ffwll.ch>
Cc: Greg KH <gregkh@linuxfoundation.org>
Signed-off-by: Noralf Trønnes <noralf@tronnes.org>
Acked-by: Gerd Hoffmann <kraxel@redhat.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20190225144232.20761-3-noralf@tronnes.org

Documentation/driver-model/devres.txt

@@ -254,6 +254,9 @@ DMA
   dmam_pool_create()
   dmam_pool_destroy()
 
+DRM
+  devm_drm_dev_init()
+
 GPIO
   devm_gpiod_get()
   devm_gpiod_get_index()

drivers/gpu/drm/drm_drv.c

@@ -601,6 +601,45 @@ err_free:
 }
 EXPORT_SYMBOL(drm_dev_init);
 
+static void devm_drm_dev_init_release(void *data)
+{
+	drm_dev_put(data);
+}
+
+/**
+ * devm_drm_dev_init - Resource managed drm_dev_init()
+ * @parent: Parent device object
+ * @dev: DRM device
+ * @driver: DRM driver
+ *
+ * Managed drm_dev_init(). The DRM device initialized with this function is
+ * automatically put on driver detach using drm_dev_put(). You must supply a
+ * &drm_driver.release callback to control the finalization explicitly.
+ *
+ * RETURNS:
+ * 0 on success, or error code on failure.
+ */
+int devm_drm_dev_init(struct device *parent,
+		      struct drm_device *dev,
+		      struct drm_driver *driver)
+{
+	int ret;
+
+	if (WARN_ON(!parent || !driver->release))
+		return -EINVAL;
+
+	ret = drm_dev_init(dev, driver, parent);
+	if (ret)
+		return ret;
+
+	ret = devm_add_action(parent, devm_drm_dev_init_release, dev);
+	if (ret)
+		devm_drm_dev_init_release(dev);
+
+	return ret;
+}
+EXPORT_SYMBOL(devm_drm_dev_init);
+
 /**
  * drm_dev_fini - Finalize a dead DRM device
  * @dev: DRM device

include/drm/drm_drv.h

@@ -718,6 +718,9 @@ extern unsigned int drm_debug;
 int drm_dev_init(struct drm_device *dev,
 		 struct drm_driver *driver,
 		 struct device *parent);
+int devm_drm_dev_init(struct device *parent,
+		      struct drm_device *dev,
+		      struct drm_driver *driver);
 void drm_dev_fini(struct drm_device *dev);
 
 struct drm_device *drm_dev_alloc(struct drm_driver *driver,