lib/uuid: Add UUID parsing function

Implement a simple function that parses a canonical UUID string into the
common byte representation. Inspired by acpigen_write_uuid().

Change-Id: Ia1bd883c740873699814fde6c6ddc1937a40093e
Signed-off-by: Nico Huber <nico.huber@secunet.com>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/36297
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Angel Pons <th3fanbus@gmail.com>

src/include/uuid.h

@@ -18,6 +18,22 @@
 
 #include <string.h>
 
+#define UUID_LEN	16
+#define UUID_STRLEN	36
+
+/*
+ * Parses a canonical UUID string into the common byte representation
+ * where the first three words are interpreted as little endian:
+ *
+ * The UUID
+ *   "00112233-4455-6677-8899-aabbccddeeff"
+ * is stored as
+ *   33 22 11 00 55 44 77 66 88 99 aa bb cc dd ee ff
+ *
+ * Returns negative value on error, 0 on success.
+ */
+int parse_uuid(uint8_t *uuid, const char *uuid_str);
+
 typedef struct {
 	uint8_t b[16];
 } __packed guid_t;

src/lib/Makefile.inc

@@ -346,3 +346,5 @@ cbfs-files-$(CONFIG_GENERIC_SPD_BIN) += spd.bin
 spd.bin-file := $(LIB_SPD_BIN)
 spd.bin-type := spd
 endif
+
+ramstage-y += uuid.c

src/lib/uuid.c

@@ -0,0 +1,35 @@
+/*
+ * This file is part of the coreboot project.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; version 2 of the License.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ */
+
+#include <stdint.h>
+#include <lib.h>
+#include <uuid.h>
+
+int parse_uuid(uint8_t *const uuid, const char *const uuid_str)
+{
+	const uint8_t order[] = { 3, 2, 1, 0, 5, 4, 7, 6, 8, 9, 10, 11, 12, 13, 14, 15 };
+	uint8_t uuid_binstr[UUID_LEN];
+	unsigned int i;
+
+	if (strlen(uuid_str) != UUID_STRLEN)
+		return -1;
+	if (uuid_str[8] != '-' || uuid_str[13] != '-' ||
+	    uuid_str[18] != '-' || uuid_str[23] != '-')
+		return -1;
+	if (hexstrtobin(uuid_str, uuid_binstr, UUID_LEN) != UUID_LEN)
+		return -1;
+	for (i = 0; i < UUID_LEN; ++i)
+		uuid[i] = uuid_binstr[order[i]];
+
+	return 0;
+}