vboot: provide RW region device support

Explicitly provide a RW view of an vboot FMAP region. This is
required for platforms which have separate implementations of
a RO boot device and a RW boot device.

BUG=chrome-os-partner:56151

Change-Id: If8bf2e1c7ca9bff536fc5c578fe0cf92ccbd2ebc
Signed-off-by: Aaron Durbin <adurbin@chromium.org>
Reviewed-on: https://review.coreboot.org/16205
Reviewed-by: Furquan Shaikh <furquan@google.com>
Tested-by: build bot (Jenkins)

src/vboot/vboot_common.c

@@ -30,6 +30,11 @@ int vboot_named_region_device(const char *name, struct region_device *rdev)
 	return fmap_locate_area_as_rdev(name, rdev);
 }
 
+int vboot_named_region_device_rw(const char *name, struct region_device *rdev)
+{
+	return fmap_locate_area_as_rdev(name, rdev);
+}
+
 /* ========================== VBOOT HANDOFF APIs =========================== */
 int vboot_get_handoff_info(void **addr, uint32_t *size)
 {

src/vboot/vboot_common.h

@@ -23,6 +23,9 @@
 /* Locate vboot area by name. Returns 0 on success and -1 on error. */
 int vboot_named_region_device(const char *name, struct region_device *rdev);
 
+/* Like vboot_named_region_device() but provides a RW region device. */
+int vboot_named_region_device_rw(const char *name, struct region_device *rdev);
+
 /*
  * Function to check if there is a request to enter recovery mode. Returns
  * reason code if request to enter recovery mode is present, otherwise 0.