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;