1 files changed, 42 insertions, 4 deletions

diff --git a/drivers/acpi/acpica/uthex.c b/drivers/acpi/acpica/uthex.c
index 4354fb800fe4..36d2fc789088 100644
--- a/drivers/acpi/acpica/uthex.c
+++ b/drivers/acpi/acpica/uthex.c
@@ -75,9 +75,41 @@ char acpi_ut_hex_to_ascii_char(u64 integer, u32 position)
 
 /*******************************************************************************
  *
+ * FUNCTION:    acpi_ut_ascii_to_hex_byte
+ *
+ * PARAMETERS:  two_ascii_chars             - Pointer to two ASCII characters
+ *              return_byte                 - Where converted byte is returned
+ *
+ * RETURN:      Status and converted hex byte
+ *
+ * DESCRIPTION: Perform ascii-to-hex translation, exactly two ASCII characters
+ *              to a single converted byte value.
+ *
+ ******************************************************************************/
+
+acpi_status acpi_ut_ascii_to_hex_byte(char *two_ascii_chars, u8 *return_byte)
+{
+
+        /* Both ASCII characters must be valid hex digits */
+
+        if (!isxdigit((int)two_ascii_chars[0]) ||
+            !isxdigit((int)two_ascii_chars[1])) {
+                return (AE_BAD_HEX_CONSTANT);
+        }
+
+        *return_byte =
+            acpi_ut_ascii_char_to_hex(two_ascii_chars[1]) |
+            (acpi_ut_ascii_char_to_hex(two_ascii_chars[0]) << 4);
+
+        return (AE_OK);
+}
+
+/*******************************************************************************
+ *
  * FUNCTION:    acpi_ut_ascii_char_to_hex
  *
- * PARAMETERS:  hex_char                - Hex character in Ascii
+ * PARAMETERS:  hex_char                - Hex character in Ascii. Must be:
+ *                                        0-9 or A-F or a-f
  *
  * RETURN:      The binary value of the ascii/hex character
  *
@@ -88,13 +120,19 @@ char acpi_ut_hex_to_ascii_char(u64 integer, u32 position)
 u8 acpi_ut_ascii_char_to_hex(int hex_char)
 {
 
-        if (hex_char <= 0x39) {
-                return ((u8)(hex_char - 0x30));
+        /* Values 0-9 */
+
+        if (hex_char <= '9') {
+                return ((u8)(hex_char - '0'));
         }
 
-        if (hex_char <= 0x46) {
+        /* Upper case A-F */
+
+        if (hex_char <= 'F') {
                 return ((u8)(hex_char - 0x37));
         }
 
+        /* Lower case a-f */
+
         return ((u8)(hex_char - 0x57));
 }