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authorMoritz Fischer <mdf@kernel.org>2017-04-24 15:05:11 -0700
committerGreg Kroah-Hartman <gregkh@linuxfoundation.org>2018-03-24 10:58:46 +0100
commitf20cb85e6f167b3341d9130f60af49123b915ae4 (patch)
tree27e8f9fc85d9382130e04421375210696d70a2e4
parent8a58463396944a0ad3f991aecedce319d48dee72 (diff)
downloadlinux-linaro-stable-f20cb85e6f167b3341d9130f60af49123b915ae4.tar.gz
rtc: ds1374: wdt: Fix issue with timeout scaling from secs to wdt ticks
[ Upstream commit 453d0744f6c6ca3f9749b8c57c2e85b5b9f52514 ] 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: 920f91e50c5b ("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> Signed-off-by: Sasha Levin <alexander.levin@microsoft.com> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
-rw-r--r--drivers/rtc/rtc-ds1374.c7
1 files changed, 6 insertions, 1 deletions
diff --git a/drivers/rtc/rtc-ds1374.c b/drivers/rtc/rtc-ds1374.c
index 3b3049c8c9e0..5b5bc7dc3a1c 100644
--- a/drivers/rtc/rtc-ds1374.c
+++ b/drivers/rtc/rtc-ds1374.c
@@ -527,6 +527,10 @@ 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;
@@ -535,7 +539,8 @@ 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;