drm/radeon/kms: add support to atom parser for FB read/write

FB read/write really doesn't need to access the actual VRAM, we
can just use a scratch area. This is required for using atom displayport
calls later.

Signed-off-by: Dave Airlie <airlied@redhat.com>
diff --git a/drivers/gpu/drm/radeon/atom.h b/drivers/gpu/drm/radeon/atom.h
index e6eb38f..6671848 100644
--- a/drivers/gpu/drm/radeon/atom.h
+++ b/drivers/gpu/drm/radeon/atom.h
@@ -132,6 +132,7 @@
 	uint8_t shift;
 	int cs_equal, cs_above;
 	int io_mode;
+	uint32_t *scratch;
 };
 
 extern int atom_debug;
@@ -142,6 +143,7 @@
 void atom_destroy(struct atom_context *);
 void atom_parse_data_header(struct atom_context *ctx, int index, uint16_t *size, uint8_t *frev, uint8_t *crev, uint16_t *data_start);
 void atom_parse_cmd_header(struct atom_context *ctx, int index, uint8_t *frev, uint8_t *crev);
+int atom_allocate_fb_scratch(struct atom_context *ctx);
 #include "atom-types.h"
 #include "atombios.h"
 #include "ObjectID.h"