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

2 files changed, 109 insertions, 0 deletions

diff --git a/drivers/gpu/drm/drm_gem_ttm_helper.c b/drivers/gpu/drm/drm_gem_ttm_helper.c
index 0e4fb9ba43ad..de28720757af 100644
--- a/drivers/gpu/drm/drm_gem_ttm_helper.c
+++ b/drivers/gpu/drm/drm_gem_ttm_helper.c
@@ -50,6 +50,43 @@ void drm_gem_ttm_print_info(struct drm_printer *p, unsigned int indent,
 EXPORT_SYMBOL(drm_gem_ttm_print_info);
 
 /**
+ * drm_gem_ttm_vmap() - vmap &ttm_buffer_object
+ * @gem: GEM object.
+ * @map: [out] returns the dma-buf mapping.
+ *
+ * Maps a GEM object with ttm_bo_vmap(). This function can be used as
+ * &drm_gem_object_funcs.vmap callback.
+ *
+ * Returns:
+ * 0 on success, or a negative errno code otherwise.
+ */
+int drm_gem_ttm_vmap(struct drm_gem_object *gem,
+		     struct dma_buf_map *map)
+{
+	struct ttm_buffer_object *bo = drm_gem_ttm_of_gem(gem);
+
+	return ttm_bo_vmap(bo, map);
+}
+EXPORT_SYMBOL(drm_gem_ttm_vmap);
+
+/**
+ * drm_gem_ttm_vunmap() - vunmap &ttm_buffer_object
+ * @gem: GEM object.
+ * @map: dma-buf mapping.
+ *
+ * Unmaps a GEM object with ttm_bo_vunmap(). This function can be used as
+ * &drm_gem_object_funcs.vmap callback.
+ */
+void drm_gem_ttm_vunmap(struct drm_gem_object *gem,
+			struct dma_buf_map *map)
+{
+	struct ttm_buffer_object *bo = drm_gem_ttm_of_gem(gem);
+
+	ttm_bo_vunmap(bo, map);
+}
+EXPORT_SYMBOL(drm_gem_ttm_vunmap);
+
+/**
  * drm_gem_ttm_mmap() - mmap &ttm_buffer_object
  * @gem: GEM object.
  * @vma: vm area.
diff --git a/drivers/gpu/drm/ttm/ttm_bo_util.c b/drivers/gpu/drm/ttm/ttm_bo_util.c
index ecb54415d1ca..7ccb2295cac1 100644
--- a/drivers/gpu/drm/ttm/ttm_bo_util.c
+++ b/drivers/gpu/drm/ttm/ttm_bo_util.c
@@ -32,6 +32,7 @@
 #include <drm/ttm/ttm_bo_driver.h>
 #include <drm/ttm/ttm_placement.h>
 #include <drm/drm_vma_manager.h>
+#include <linux/dma-buf-map.h>
 #include <linux/io.h>
 #include <linux/highmem.h>
 #include <linux/wait.h>
@@ -471,6 +472,77 @@ void ttm_bo_kunmap(struct ttm_bo_kmap_obj *map)
 }
 EXPORT_SYMBOL(ttm_bo_kunmap);
 
+int ttm_bo_vmap(struct ttm_buffer_object *bo, struct dma_buf_map *map)
+{
+	struct ttm_resource *mem = &bo->mem;
+	int ret;
+
+	ret = ttm_mem_io_reserve(bo->bdev, mem);
+	if (ret)
+		return ret;
+
+	if (mem->bus.is_iomem) {
+		void __iomem *vaddr_iomem;
+		size_t size = bo->num_pages << PAGE_SHIFT;
+
+		if (mem->bus.addr)
+			vaddr_iomem = (void __iomem *)mem->bus.addr;
+		else if (mem->bus.caching == ttm_write_combined)
+			vaddr_iomem = ioremap_wc(mem->bus.offset, size);
+		else
+			vaddr_iomem = ioremap(mem->bus.offset, size);
+
+		if (!vaddr_iomem)
+			return -ENOMEM;
+
+		dma_buf_map_set_vaddr_iomem(map, vaddr_iomem);
+
+	} else {
+		struct ttm_operation_ctx ctx = {
+			.interruptible = false,
+			.no_wait_gpu = false
+		};
+		struct ttm_tt *ttm = bo->ttm;
+		pgprot_t prot;
+		void *vaddr;
+
+		ret = ttm_tt_populate(bo->bdev, ttm, &ctx);
+		if (ret)
+			return ret;
+
+		/*
+		 * We need to use vmap to get the desired page protection
+		 * or to make the buffer object look contiguous.
+		 */
+		prot = ttm_io_prot(bo, mem, PAGE_KERNEL);
+		vaddr = vmap(ttm->pages, bo->num_pages, 0, prot);
+		if (!vaddr)
+			return -ENOMEM;
+
+		dma_buf_map_set_vaddr(map, vaddr);
+	}
+
+	return 0;
+}
+EXPORT_SYMBOL(ttm_bo_vmap);
+
+void ttm_bo_vunmap(struct ttm_buffer_object *bo, struct dma_buf_map *map)
+{
+	struct ttm_resource *mem = &bo->mem;
+
+	if (dma_buf_map_is_null(map))
+		return;
+
+	if (!map->is_iomem)
+		vunmap(map->vaddr);
+	else if (!mem->bus.addr)
+		iounmap(map->vaddr_iomem);
+	dma_buf_map_clear(map);
+
+	ttm_mem_io_free(bo->bdev, &bo->mem);
+}
+EXPORT_SYMBOL(ttm_bo_vunmap);
+
 static int ttm_bo_wait_free_node(struct ttm_buffer_object *bo,
 				 bool dst_use_tt)
 {