drm: Add DRM_GEM_FOPS

The DEFINE_DRM_GEM_FOPS() helper is a bit limiting if a driver wants to
provide additional file ops, like show_fdinfo().

v2: Split out DRM_GEM_FOPS instead of making DEFINE_DRM_GEM_FOPS
    varardic
v3: nits

Signed-off-by: Rob Clark <robdclark@chromium.org>
Acked-by: Thomas Zimmermann <tzimmermann@suse.de>
Patchwork: https://patchwork.freedesktop.org/patch/488904/
Link: https://lore.kernel.org/r/20220609174213.2265938-1-robdclark@gmail.com
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>

include/drm/drm_gem.h

@@ -314,6 +314,23 @@ struct drm_gem_object {
 	const struct drm_gem_object_funcs *funcs;
 };
 
+/**
+ * DRM_GEM_FOPS - Default drm GEM file operations
+ *
+ * This macro provides a shorthand for setting the GEM file ops in the
+ * &file_operations structure.  If all you need are the default ops, use
+ * DEFINE_DRM_GEM_FOPS instead.
+ */
+#define DRM_GEM_FOPS \
+	.open		= drm_open,\
+	.release	= drm_release,\
+	.unlocked_ioctl	= drm_ioctl,\
+	.compat_ioctl	= drm_compat_ioctl,\
+	.poll		= drm_poll,\
+	.read		= drm_read,\
+	.llseek		= noop_llseek,\
+	.mmap		= drm_gem_mmap
+
 /**
  * DEFINE_DRM_GEM_FOPS() - macro to generate file operations for GEM drivers
  * @name: name for the generated structure
@@ -330,14 +347,7 @@ struct drm_gem_object {
 #define DEFINE_DRM_GEM_FOPS(name) \
 	static const struct file_operations name = {\
 		.owner		= THIS_MODULE,\
-		.open		= drm_open,\
-		.release	= drm_release,\
-		.unlocked_ioctl	= drm_ioctl,\
-		.compat_ioctl	= drm_compat_ioctl,\
-		.poll		= drm_poll,\
-		.read		= drm_read,\
-		.llseek		= noop_llseek,\
-		.mmap		= drm_gem_mmap,\
+		DRM_GEM_FOPS,\
 	}
 
 void drm_gem_object_release(struct drm_gem_object *obj);