diff mbox series

[v2,1/2] include/linux/bcd.h: provide bcd_is_valid() helper

Message ID 20220817085330.1050492-2-s.hauer@pengutronix.de
State Superseded
Headers show
Series rtc: rv8803 patches | expand

Commit Message

Sascha Hauer Aug. 17, 2022, 8:53 a.m. UTC 
From: Ahmad Fatoum <a.fatoum@pengutronix.de>

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>
---
 include/linux/bcd.h | 4 ++++
 1 file changed, 4 insertions(+)
diff mbox series

Patch

diff --git a/include/linux/bcd.h b/include/linux/bcd.h
index 118bea36d7d49..abbc8149178e6 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__;