libpayload/libc/fmap: Implement new FlashMap API

This patch introduces new FlashMap API, the fmap_locate_area().
It works on cached FlashMap provided in lib_sysinfo.fmap_cache.

Change-Id: Idbf9016ce73aa58e17f3ee19920ab83dc6c25abb
Signed-off-by: Jakub Czapiga <jacz@semihalf.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/59494
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Julius Werner <jwerner@chromium.org>

payloads/libpayload/include/fmap.h

@@ -0,0 +1,12 @@
+/* SPDX_License-Identifier: BSD-3-Clause */
+
+#ifndef _FMAP_H
+#define _FMAP_H
+
+#include <commonlib/bsd/cb_err.h>
+#include <stddef.h>
+
+/* Looks for area with |name| in FlashMap. Requires lib_sysinfo.fmap_cache. */
+cb_err_t fmap_locate_area(const char *name, size_t *offset, size_t *size);
+
+#endif /* _FMAP_H */