[PATCHv3] vsprintf: Add %pMR for Bluetooth MAC address

[Andrei Emeltchenko <Andrei.Emeltchenko.news@gmail.com>]

From: Andrei Emeltchenko <andrei.emeltchenko@intel.com>

Bluetooth uses mostly LE byte order which is reversed for visual
interpretation. Currently in Bluetooth in use unsafe batostr function.

This is slightly modified version of Joe Perches <joe@perches.com>
patch (sent Sat, Dec 4, 2010).

Signed-off-by: Andrei Emeltchenko <andrei.emeltchenko@intel.com>
---
	v3: removed extra variable index
	v2: changed bluetooth to reversed, syntax fixes

 lib/vsprintf.c |   23 +++++++++++++++++++----
 1 file changed, 19 insertions(+), 4 deletions(-)

diff --git a/lib/vsprintf.c b/lib/vsprintf.c
index abbabec..55052fa 100644
--- a/lib/vsprintf.c
+++ b/lib/vsprintf.c
@@ -559,15 +559,28 @@ char *mac_address_string(char *buf, char *end, u8 *addr,
 	char *p = mac_addr;
 	int i;
 	char separator;
+	bool reversed = false;
 
-	if (fmt[1] == 'F') {		/* FDDI canonical format */
+	switch (fmt[1]) {
+	case 'F':
 		separator = '-';
-	} else {
+		break;
+
+	case 'R':
+		reversed = true;
+		/* fall through */
+
+	default:
 		separator = ':';
+		break;
 	}
 
 	for (i = 0; i < 6; i++) {
-		p = hex_byte_pack(p, addr[i]);
+		if (reversed)
+			p = hex_byte_pack(p, addr[5 - i]);
+		else
+			p = hex_byte_pack(p, addr[i]);
+
 		if (fmt[0] == 'M' && i != 5)
 			*p++ = separator;
 	}
@@ -830,6 +843,7 @@ int kptr_restrict __read_mostly;
  * - 'm' For a 6-byte MAC address, it prints the hex address without colons
  * - 'MF' For a 6-byte MAC FDDI address, it prints the address
  *       with a dash-separated hex notation
+ * - '[mM]R For a 6-byte MAC address, Reverse order (Bluetooth)
  * - 'I' [46] for IPv4/IPv6 addresses printed in the usual way
  *       IPv4 uses dot-separated decimal without leading 0's (1.2.3.4)
  *       IPv6 uses colon separated network-order 16 bit hex with leading 0's
@@ -890,7 +904,8 @@ char *pointer(const char *fmt, char *buf, char *end, void *ptr,
 		return resource_string(buf, end, ptr, spec, fmt);
 	case 'M':			/* Colon separated: 00:01:02:03:04:05 */
 	case 'm':			/* Contiguous: 000102030405 */
-					/* [mM]F (FDDI, bit reversed) */
+					/* [mM]F (FDDI) */
+					/* [mM]R (Reverse order; Bluetooth) */
 		return mac_address_string(buf, end, ptr, spec, fmt);
 	case 'I':			/* Formatted IP supported
 					 * 4:	1.2.3.4
-- 
1.7.9.5