From: Ahmad Fatoum <a.fatoum@pengutronix.de>
Date: Wed, 23 Nov 2022 09:55:26 +0000 (+0100)
Subject: include/linux/bcd.h: provide bcd_is_valid() helper
X-Git-Tag: v6.6.17~5374^2~40
X-Git-Url: http://review.tizen.org/git/?a=commitdiff_plain;h=19409796578c879a41e88ddbdbce50c19457658d;p=platform%2Fkernel%2Flinux-rpi.git

include/linux/bcd.h: provide bcd_is_valid() helper

bcd2bin(0x0A) happily returns 10, despite this being an invalid BCD
value. RTC drivers converting possibly corrupted BCD timestamps might
want to validate their input before calling bcd2bin().

Provide a macro to do so. Unlike bcd2bin and bin2bcd, out-of-line
versions are not implemented. Should the macro experience enough use,
this can be retrofitted.

Signed-off-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
Link: https://lore.kernel.org/r/20221123095527.2771434-2-s.hauer@pengutronix.de
Signed-off-by: Alexandre Belloni <alexandre.belloni@bootlin.com>
---

diff --git a/include/linux/bcd.h b/include/linux/bcd.h
index 118bea3..abbc814 100644
--- a/include/linux/bcd.h
+++ b/include/linux/bcd.h
@@ -14,8 +14,12 @@
 		const_bin2bcd(x) :			\
 		_bin2bcd(x))
 
+#define bcd_is_valid(x)					\
+		const_bcd_is_valid(x)
+
 #define const_bcd2bin(x)	(((x) & 0x0f) + ((x) >> 4) * 10)
 #define const_bin2bcd(x)	((((x) / 10) << 4) + (x) % 10)
+#define const_bcd_is_valid(x)	(((x) & 0x0f) < 10 && ((x) >> 4) < 10)
 
 unsigned _bcd2bin(unsigned char val) __attribute_const__;
 unsigned char _bin2bcd(unsigned val) __attribute_const__;