drm/ttm: Add vmap/vunmap to TTM and TTM GEM helpers

The new functions ttm_bo_{vmap,vunmap}() map and unmap a TTM BO in kernel
address space. The mapping's address is returned as struct dma_buf_map.
Each function is a simplified version of TTM's existing kmap code. Both
functions respect the memory's location ani/or writecombine flags.

On top TTM's functions, GEM TTM helpers got drm_gem_ttm_{vmap,vunmap}(),
two helpers that convert a GEM object into the TTM BO and forward the call
to TTM's vmap/vunmap. These helpers can be dropped into the rsp GEM object
callbacks.

v5:
	* use size_t for storing mapping size (Christian)
	* ignore premapped memory areas correctly in ttm_bo_vunmap()
	* rebase onto latest TTM interfaces (Christian)
	* remove BUG() from ttm_bo_vmap() (Christian)
v4:
	* drop ttm_kmap_obj_to_dma_buf() in favor of vmap helpers (Daniel,
	  Christian)

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Christian König <christian.koenig@amd.com>
Acked-by: Daniel Vetter <daniel.vetter@ffwll.ch>
Tested-by: Sam Ravnborg <sam@ravnborg.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20201103093015.1063-6-tzimmermann@suse.de

1 files changed, 28 insertions, 0 deletions

diff --git a/include/drm/ttm/ttm_bo_api.h b/include/drm/ttm/ttm_bo_api.h
index 5ddad88ae6ed..2564e66e67d7 100644
--- a/include/drm/ttm/ttm_bo_api.h
+++ b/include/drm/ttm/ttm_bo_api.h
@@ -48,6 +48,8 @@ struct ttm_bo_global;
 
 struct ttm_bo_device;
 
+struct dma_buf_map;
+
 struct drm_mm_node;
 
 struct ttm_placement;
@@ -496,6 +498,32 @@ int ttm_bo_kmap(struct ttm_buffer_object *bo, unsigned long start_page,
 void ttm_bo_kunmap(struct ttm_bo_kmap_obj *map);
 
 /**
+ * ttm_bo_vmap
+ *
+ * @bo: The buffer object.
+ * @map: pointer to a struct dma_buf_map representing the map.
+ *
+ * Sets up a kernel virtual mapping, using ioremap or vmap to the
+ * data in the buffer object. The parameter @map returns the virtual
+ * address as struct dma_buf_map. Unmap the buffer with ttm_bo_vunmap().
+ *
+ * Returns
+ * -ENOMEM: Out of memory.
+ * -EINVAL: Invalid range.
+ */
+int ttm_bo_vmap(struct ttm_buffer_object *bo, struct dma_buf_map *map);
+
+/**
+ * ttm_bo_vunmap
+ *
+ * @bo: The buffer object.
+ * @map: Object describing the map to unmap.
+ *
+ * Unmaps a kernel map set up by ttm_bo_vmap().
+ */
+void ttm_bo_vunmap(struct ttm_buffer_object *bo, struct dma_buf_map *map);
+
+/**
  * ttm_bo_mmap_obj - mmap memory backed by a ttm buffer object.
  *
  * @vma:       vma as input from the fbdev mmap method.