drm/ttm: add drm_gem_ttm_mmap()

Add helper function to mmap ttm bo's using &drm_gem_object_funcs.mmap().

Note that with this code path access verification is done by
drm_gem_mmap() (which calls drm_vma_node_is_allowed(()).
The &ttm_bo_driver.verify_access() callback is is not used.

v3: use ttm_bo_mmap_obj instead of ttm_bo_mmap_vma_setup
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Reviewed-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Link: http://patchwork.freedesktop.org/patch/msgid/20191016115203.20095-9-kraxel@redhat.com

drivers/gpu/drm/drm_gem_ttm_helper.c

@@ -52,5 +52,22 @@ void drm_gem_ttm_print_info(struct drm_printer *p, unsigned int indent,
 }
 EXPORT_SYMBOL(drm_gem_ttm_print_info);
 
+/**
+ * drm_gem_ttm_mmap() - mmap &ttm_buffer_object
+ * @gem: GEM object.
+ * @vma: vm area.
+ *
+ * This function can be used as &drm_gem_object_funcs.mmap
+ * callback.
+ */
+int drm_gem_ttm_mmap(struct drm_gem_object *gem,
+		     struct vm_area_struct *vma)
+{
+	struct ttm_buffer_object *bo = drm_gem_ttm_of_gem(gem);
+
+	return ttm_bo_mmap_obj(vma, bo);
+}
+EXPORT_SYMBOL(drm_gem_ttm_mmap);
+
 MODULE_DESCRIPTION("DRM gem ttm helpers");
 MODULE_LICENSE("GPL");

include/drm/drm_gem_ttm_helper.h

@@ -15,5 +15,7 @@
 
 void drm_gem_ttm_print_info(struct drm_printer *p, unsigned int indent,
 			    const struct drm_gem_object *gem);
+int drm_gem_ttm_mmap(struct drm_gem_object *gem,
+		     struct vm_area_struct *vma);
 
 #endif