Fix the issue of max_timeout being calculated larger than actual value.
The calculation result of freq / (S3C2410_WTCON_PRESCALE_MAX + 1) /
S3C2410_WTCON_MAXDIV is smaller than the actual value because the remainder
is discarded during the calculation process. This leads to a larger
calculated value for max_timeout compared to the actual settable value.
To resolve this issue, the order of calculations in the computation process
has been adjusted.
Reviewed-by: Sam Protsenko <semen.protsenko@xxxxxxxxxx>
Signed-off-by: Sangwook Shin <sw617.shin@xxxxxxxxxxx>
---
drivers/watchdog/s3c2410_wdt.c | 10 ++++++++--
1 file changed, 8 insertions(+), 2 deletions(-)
diff --git a/drivers/watchdog/s3c2410_wdt.c b/drivers/watchdog/s3c2410_wdt.c
index 95f7207e390a..1e8cf0299713 100644
--- a/drivers/watchdog/s3c2410_wdt.c
+++ b/drivers/watchdog/s3c2410_wdt.c
@@ -27,6 +27,7 @@
#include <linux/mfd/syscon.h>
#include <linux/regmap.h>
#include <linux/delay.h>
+#include <linux/math64.h>
#define S3C2410_WTCON 0x00
#define S3C2410_WTDAT 0x04
@@ -410,9 +411,14 @@ static inline unsigned long s3c2410wdt_get_freq(struct s3c2410_wdt *wdt)
static inline unsigned int s3c2410wdt_max_timeout(struct s3c2410_wdt *wdt)
{
const unsigned long freq = s3c2410wdt_get_freq(wdt);
+ const u64 n_max = (u64)(S3C2410_WTCON_PRESCALE_MAX + 1) *
+ S3C2410_WTCON_MAXDIV * S3C2410_WTCNT_MAXCNT;
+ u64 t_max = div64_ul(n_max, freq);
- return S3C2410_WTCNT_MAXCNT / (freq / (S3C2410_WTCON_PRESCALE_MAX + 1)
- / S3C2410_WTCON_MAXDIV);
+ if (t_max > UINT_MAX)
+ t_max = UINT_MAX;
+
+ return t_max;
}
static int s3c2410wdt_disable_wdt_reset(struct s3c2410_wdt *wdt, bool mask)
--
2.25.1
