disk: part_efi: parse and store partition UUID

Each EFI partition table entry contains a UUID. Extend U-Boot's struct
disk_partition to be able to store this information, and modify
get_partition_info_efi() to fill it in.

The implementation of uuid_string() was derived from the Linux kernel,
tag v3.6-rc4 file lib/vsprintf.c function uuid_string().

Signed-off-by: Stephen Warren <swarren@nvidia.com>
diff --git a/disk/part_efi.c b/disk/part_efi.c
index 2962fd8..264ea9c 100644
--- a/disk/part_efi.c
+++ b/disk/part_efi.c
@@ -154,6 +154,28 @@
 	return;
 }
 
+#ifdef CONFIG_PARTITION_UUIDS
+static void uuid_string(unsigned char *uuid, char *str)
+{
+	static const u8 le[16] = {3, 2, 1, 0, 5, 4, 7, 6, 8, 9, 10, 11,
+				  12, 13, 14, 15};
+	int i;
+
+	for (i = 0; i < 16; i++) {
+		sprintf(str, "%02x", uuid[le[i]]);
+		str += 2;
+		switch (i) {
+		case 3:
+		case 5:
+		case 7:
+		case 9:
+			*str++ = '-';
+			break;
+		}
+	}
+}
+#endif
+
 int get_partition_info_efi(block_dev_desc_t * dev_desc, int part,
 				disk_partition_t * info)
 {
@@ -190,6 +212,9 @@
 	sprintf((char *)info->name, "%s",
 			print_efiname(&gpt_pte[part - 1]));
 	sprintf((char *)info->type, "U-Boot");
+#ifdef CONFIG_PARTITION_UUIDS
+	uuid_string(gpt_pte[part - 1].unique_partition_guid.b, info->uuid);
+#endif
 
 	debug("%s: start 0x%lX, size 0x%lX, name %s", __func__,
 		info->start, info->size, info->name);