[PATCH v4 03/10] lib: uuid: introduce be_uuid_str_to_le_bin function

[Abdellatif El Khlifi]

convert big endian UUID string to little endian buffer

Changelog:
===============

v4:

* rename ffa_uuid_str_to_bin to be_uuid_str_to_le_bin and put in
  a standalone commit (the current)

v3:

* introduce ffa_uuid_str_to_bin (provided by
  arm_ffa: introduce Arm FF-A low-level driver)

Signed-off-by: Abdellatif El Khlifi <abdellatif.elkhlifi at arm.com>
Cc: Tom Rini <trini at konsulko.com>
Cc: Simon Glass <sjg at chromium.org>
Cc: Ilias Apalodimas <ilias.apalodimas at linaro.org>
Cc: Jens Wiklander <jens.wiklander at linaro.org>
---
 include/uuid.h |  8 +++++++
 lib/uuid.c     | 64 ++++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 72 insertions(+)

diff --git a/include/uuid.h b/include/uuid.h
index 4a4883d3b5..ad3af350f9 100644
--- a/include/uuid.h
+++ b/include/uuid.h
@@ -2,6 +2,8 @@
 /*
  * Copyright (C) 2014 Samsung Electronics
  * Przemyslaw Marczak <p.marczak at samsung.com>
+ * (C) Copyright 2022 ARM Limited
+ * Abdellatif El Khlifi <abdellatif.elkhlifi at arm.com>
  */
 #ifndef __UUID_H__
 #define __UUID_H__
@@ -44,4 +46,10 @@ int uuid_guid_get_bin(const char *guid_str, unsigned char *guid_bin);
 const char *uuid_guid_get_str(const unsigned char *guid_bin);
 void gen_rand_uuid(unsigned char *uuid_bin);
 void gen_rand_uuid_str(char *uuid_str, int str_format);
+
+/**
+ * be_uuid_str_to_le_bin - Converts a big endian UUID string to a little endian buffer
+ */
+int be_uuid_str_to_le_bin(const char *uuid_str, unsigned char *uuid_bin);
+
 #endif
diff --git a/lib/uuid.c b/lib/uuid.c
index 465e1ac38f..15a9ab49d5 100644
--- a/lib/uuid.c
+++ b/lib/uuid.c
@@ -1,6 +1,8 @@
 // SPDX-License-Identifier: GPL-2.0+
 /*
  * Copyright 2011 Calxeda, Inc.
+ * (C) Copyright 2022 ARM Limited
+ * Abdellatif El Khlifi <abdellatif.elkhlifi at arm.com>
  */
 
 #include <common.h>
@@ -346,6 +348,68 @@ int uuid_str_to_bin(const char *uuid_str, unsigned char *uuid_bin,
 	return 0;
 }
 
+/**
+ * be_uuid_str_to_le_bin - Converts a big endian UUID string to a little endian buffer
+ * @uuid_str:	UUID string in big endian format (36 bytes wide + '/0')
+ * @uuid_bin:	preallocated 16 bytes UUID buffer in little endian format
+ *
+ * UUID string is 36 characters (36 bytes):
+ *
+ * xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx
+ * be		     be	     be	      be      be
+ *
+ * where x is a hexadecimal character. Fields are separated by '-'s.
+ * When converting to a binary UUID, these endianness rules apply:
+ *     be: means the field in the string is considered a big endian hex number
+ *	   and should be converted to little endian binary format
+ *
+ * Return:
+ *
+ *    uuid_bin filled with little endian UUID data
+ *    On success 0 is returned. Otherwise, failure code.
+ */
+int be_uuid_str_to_le_bin(const char *uuid_str, unsigned char *uuid_bin)
+{
+	u16 tmp16 = 0;
+	u32 tmp32 = 0;
+	u64 tmp64 = 0;
+
+	if (!uuid_str_valid(uuid_str) || !uuid_bin)
+		return -EINVAL;
+
+	/*
+	 * reverse bytes from big to little endian
+	 */
+	tmp32 = simple_strtoul(uuid_str, NULL, 16);
+	memcpy(uuid_bin, &tmp32, 4);
+
+	/*
+	 * reverse bytes from big to little endian
+	 */
+	tmp16 = simple_strtoul(uuid_str + 9, NULL, 16);
+	memcpy(uuid_bin + 4, &tmp16, 2);
+
+	/*
+	 * reverse bytes from big to little endian
+	 */
+	tmp16 = simple_strtoul(uuid_str + 14, NULL, 16);
+	memcpy(uuid_bin + 6, &tmp16, 2);
+
+	/*
+	 * reverse bytes from big to little endian
+	 */
+	tmp16 = simple_strtoul(uuid_str + 19, NULL, 16);
+	memcpy(uuid_bin + 8, &tmp16, 2);
+
+	/*
+	 * reverse bytes from big to little endian
+	 */
+	tmp64 = simple_strtoull(uuid_str + 24, NULL, 16);
+	memcpy(uuid_bin + 10, (char *)&tmp64, 6);
+
+	return 0;
+}
+
 /*
  * uuid_bin_to_str() - convert big endian binary data to string UUID or GUID.
  *
-- 
2.17.1