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List: linux-rtc
Subject: [PATCH 4/5] include/linux/bcd.h: provide bcd_is_valid() helper
From: Sascha Hauer <s.hauer () pengutronix ! de>
Date: 2022-04-26 7:10:55
Message-ID: 20220426071056.1187235-5-s.hauer () pengutronix ! de
[Download RAW message or body]
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>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>
---
include/linux/bcd.h | 4 ++++
1 file changed, 4 insertions(+)
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__;
--
2.30.2
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