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rtc: ds1374: wdt: Fix issue with timeout scaling from secs to wdt ticks 

The issue is that the internal counter that triggers the watchdog reset
is actually running at 4096 Hz instead of 1Hz, therefore the value
given by userland (in sec) needs to be multiplied by 4096 to get the
correct behavior.

Fixes: 920f91e50c ("drivers/rtc/rtc-ds1374.c: add watchdog support")
Signed-off-by: Moritz Fischer <mdf@kernel.org>
Signed-off-by: Alexandre Belloni <alexandre.belloni@free-electrons.com>
This commit is contained in:
Moritz Fischer 2017-04-24 15:05:11 -07:00 committed by Alexandre Belloni
parent 5d05e81516
commit 453d0744f6
1 changed files with 6 additions and 1 deletions
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7
drivers/rtc/rtc-ds1374.c
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@ -525,6 +525,10 @@ static long ds1374_wdt_ioctl(struct file *file, unsigned int cmd,
if (get_user(new_margin, (int __user *)arg))
return -EFAULT;
/* the hardware's tick rate is 4096 Hz, so
* the counter value needs to be scaled accordingly
*/
new_margin <<= 12;
if (new_margin < 1 || new_margin > 16777216)
return -EINVAL;
@ -533,7 +537,8 @@ static long ds1374_wdt_ioctl(struct file *file, unsigned int cmd,
ds1374_wdt_ping();
/* fallthrough */
case WDIOC_GETTIMEOUT:
return put_user(wdt_margin, (int __user *)arg);
/* when returning ... inverse is true */
return put_user((wdt_margin >> 12), (int __user *)arg);
case WDIOC_SETOPTIONS:
if (copy_from_user(&options, (int __user *)arg, sizeof(int)))
return -EFAULT;