linux-kernel - [PATCH v3 1/2] vsprintf: Add %p[mM]U for uppercase MAC address

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Message-Id: <20230427115120.241954-1-k.graefe@gateware.de>
Date:   Thu, 27 Apr 2023 13:51:19 +0200
From:   Konrad Gräfe <k.graefe@...eware.de>
To:     Quentin Schulz <quentin.schulz@...obroma-systems.com>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Petr Mladek <pmladek@...e.com>,
        Steven Rostedt <rostedt@...dmis.org>,
        Sergey Senozhatsky <senozhatsky@...omium.org>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Rasmus Villemoes <linux@...musvillemoes.dk>,
        linux-usb@...r.kernel.org, linux-kernel@...r.kernel.org,
        Kyungmin Park <kyungmin.park@...sung.com>,
        Andrzej Pietrasiewicz <andrzej.p@...labora.com>,
        Felipe Balbi <balbi@...com>
Cc:     Konrad Gräfe <k.graefe@...eware.de>,
        stable@...r.kernel.org
Subject: [PATCH v3 1/2] vsprintf: Add %p[mM]U for uppercase MAC address

The CDC-ECM specification requires an USB gadget to send the host MAC
address as uppercase hex string. This change adds the appropriate
modifier.

Cc: stable@...r.kernel.org
Signed-off-by: Konrad Gräfe <k.graefe@...eware.de>
---
Added in v3

 lib/vsprintf.c | 18 +++++++++++++++---
 1 file changed, 15 insertions(+), 3 deletions(-)

diff --git a/lib/vsprintf.c b/lib/vsprintf.c
index be71a03c936a..8aee1caabd9e 100644
--- a/lib/vsprintf.c
+++ b/lib/vsprintf.c
@@ -1269,9 +1269,10 @@ char *mac_address_string(char *buf, char *end, u8 *addr,
 {
 	char mac_addr[sizeof("xx:xx:xx:xx:xx:xx")];
 	char *p = mac_addr;
-	int i;
+	int i, pos;
 	char separator;
 	bool reversed = false;
+	bool uppercase = false;
 
 	if (check_pointer(&buf, end, addr, spec))
 		return buf;
@@ -1281,6 +1282,10 @@ char *mac_address_string(char *buf, char *end, u8 *addr,
 		separator = '-';
 		break;
 
+	case 'U':
+		uppercase = true;
+		break;
+
 	case 'R':
 		reversed = true;
 		fallthrough;
@@ -1292,9 +1297,14 @@ char *mac_address_string(char *buf, char *end, u8 *addr,
 
 	for (i = 0; i < 6; i++) {
 		if (reversed)
-			p = hex_byte_pack(p, addr[5 - i]);
+			pos = 5 - i;
+		else
+			pos = i;
+
+		if (uppercase)
+			p = hex_byte_pack_upper(p, addr[pos]);
 		else
-			p = hex_byte_pack(p, addr[i]);
+			p = hex_byte_pack(p, addr[pos]);
 
 		if (fmt[0] == 'M' && i != 5)
 			*p++ = separator;
@@ -2279,6 +2289,7 @@ char *rust_fmt_argument(char *buf, char *end, void *ptr);
  * - '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]U' For a 6-byte MAC address in uppercase hex
  * - '[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)
@@ -2407,6 +2418,7 @@ char *pointer(const char *fmt, char *buf, char *end, void *ptr,
 	case 'M':			/* Colon separated: 00:01:02:03:04:05 */
 	case 'm':			/* Contiguous: 000102030405 */
 					/* [mM]F (FDDI) */
+					/* [mM]U (Uppercase hex) */
 					/* [mM]R (Reverse order; Bluetooth) */
 		return mac_address_string(buf, end, ptr, spec, fmt);
 	case 'I':			/* Formatted IP supported
-- 
2.34.1