libpayload: Implement new CBFS access API

This commit adds new CBFS API, which is based on the one available in
the main coreboot source tree. Libpayload implementation supports RO/RW
file lookups and file contents verification.

Change-Id: I00da0658dbac0cddf92ad55611def947932d23c7
Signed-off-by: Jakub Czapiga <jacz@semihalf.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/59497
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Julius Werner <jwerner@chromium.org>

payloads/libpayload/include/cbfs_glue.h

@@ -0,0 +1,46 @@
+/* SPDX-License-Identifier: BSD-3-Clause */
+
+#ifndef _CBFS_CBFS_GLUE_H
+#define _CBFS_CBFS_GLUE_H
+
+#include <libpayload-config.h>
+#include <boot_device.h>
+#include <stdio.h>
+
+#define CBFS_ENABLE_HASHING CONFIG(LP_CBFS_VERIFICATION)
+
+#define ERROR(...) printf("CBFS ERROR: " __VA_ARGS__)
+#define LOG(...) printf("CBFS: " __VA_ARGS__)
+#define DEBUG(...)                                                                             \
+	do {                                                                                   \
+		if (CONFIG(LP_DEBUG_CBFS))                                                     \
+			printf("CBFS DEBUG: " __VA_ARGS__);                                    \
+	} while (0)
+
+struct cbfs_dev {
+	size_t offset;
+	size_t size;
+};
+
+struct cbfs_boot_device {
+	struct cbfs_dev dev;
+	void *mcache;
+	size_t mcache_size;
+};
+
+typedef const struct cbfs_dev *cbfs_dev_t;
+
+static inline ssize_t cbfs_dev_read(cbfs_dev_t dev, void *buffer, size_t offset, size_t size)
+{
+	if (offset + size < offset || offset + size > dev->size)
+		return CB_ERR_ARG;
+
+	return boot_device_read(buffer, dev->offset + offset, size);
+}
+
+static inline size_t cbfs_dev_size(cbfs_dev_t dev)
+{
+	return dev->size;
+}
+
+#endif /* _CBFS_CBFS_GLUE_H */