drm/gem: Provide drm_gem_fb_{vmap,vunmap}()

Move framebuffer vmap code from shadow-buffered plane state into the new
interfaces drm_gem_fb_vmap() and drm_gem_fb_vunmap(). These functions
provide mappings of a framebuffer's BOs into kernel address space. No
functional changes.

v4:
	* remove duplicated blank line
v2:
	* using [static N] for array parameters enables compile-time checks
	* include <drm/drm_fourcc.h> for DRM_FORMAT_MAX_PLANES (kernel
	  test robot)

Signed-off-by: Thomas Zimmermann <tzimmermann@suse.de>
Reviewed-by: Sam Ravnborg <sam@ravnborg.org>
Link: https://patchwork.freedesktop.org/patch/msgid/20210730183511.20080-3-tzimmermann@suse.de

1 files changed, 72 insertions, 0 deletions

diff --git a/drivers/gpu/drm/drm_gem_framebuffer_helper.c b/drivers/gpu/drm/drm_gem_framebuffer_helper.c
index 421e029a6b3e..2bc0605c8bca 100644
--- a/drivers/gpu/drm/drm_gem_framebuffer_helper.c
+++ b/drivers/gpu/drm/drm_gem_framebuffer_helper.c
@@ -15,6 +15,8 @@
 #include <drm/drm_gem_framebuffer_helper.h>
 #include <drm/drm_modeset_helper.h>
 
+#include "drm_internal.h"
+
 #define AFBC_HEADER_SIZE		16
 #define AFBC_TH_LAYOUT_ALIGNMENT	8
 #define AFBC_HDR_ALIGN			64
@@ -310,6 +312,76 @@ drm_gem_fb_create_with_dirty(struct drm_device *dev, struct drm_file *file,
 EXPORT_SYMBOL_GPL(drm_gem_fb_create_with_dirty);
 
 /**
+ * drm_gem_fb_vmap - maps all framebuffer BOs into kernel address space
+ * @fb: the framebuffer
+ * @map: returns the mapping's address for each BO
+ *
+ * This function maps all buffer objects of the given framebuffer into
+ * kernel address space and stores them in struct dma_buf_map. If the
+ * mapping operation fails for one of the BOs, the function unmaps the
+ * already established mappings automatically.
+ *
+ * See drm_gem_fb_vunmap() for unmapping.
+ *
+ * Returns:
+ * 0 on success, or a negative errno code otherwise.
+ */
+int drm_gem_fb_vmap(struct drm_framebuffer *fb,
+		    struct dma_buf_map map[static DRM_FORMAT_MAX_PLANES])
+{
+	struct drm_gem_object *obj;
+	unsigned int i;
+	int ret;
+
+	for (i = 0; i < DRM_FORMAT_MAX_PLANES; ++i) {
+		obj = drm_gem_fb_get_obj(fb, i);
+		if (!obj)
+			continue;
+		ret = drm_gem_vmap(obj, &map[i]);
+		if (ret)
+			goto err_drm_gem_vunmap;
+	}
+
+	return 0;
+
+err_drm_gem_vunmap:
+	while (i) {
+		--i;
+		obj = drm_gem_fb_get_obj(fb, i);
+		if (!obj)
+			continue;
+		drm_gem_vunmap(obj, &map[i]);
+	}
+	return ret;
+}
+EXPORT_SYMBOL(drm_gem_fb_vmap);
+
+/**
+ * drm_gem_fb_vunmap - unmaps framebuffer BOs from kernel address space
+ * @fb: the framebuffer
+ * @map: mapping addresses as returned by drm_gem_fb_vmap()
+ *
+ * This function unmaps all buffer objects of the given framebuffer.
+ *
+ * See drm_gem_fb_vmap() for more information.
+ */
+void drm_gem_fb_vunmap(struct drm_framebuffer *fb,
+		       struct dma_buf_map map[static DRM_FORMAT_MAX_PLANES])
+{
+	unsigned int i = DRM_FORMAT_MAX_PLANES;
+	struct drm_gem_object *obj;
+
+	while (i) {
+		--i;
+		obj = drm_gem_fb_get_obj(fb, i);
+		if (!obj)
+			continue;
+		drm_gem_vunmap(obj, &map[i]);
+	}
+}
+EXPORT_SYMBOL(drm_gem_fb_vunmap);
+
+/**
  * drm_gem_fb_begin_cpu_access - prepares GEM buffer objects for CPU access
  * @fb: the framebuffer
  * @dir: access mode