watchdog: Handle timer wrap around

On some platforms/architectures the value from get_timer() can wrap.
This is particularly problematic when long-running code needs to measure
a time difference as is the case with watchdog_reset() which tries to
avoid tickling the watchdog too frequently.

Use time_after() from time.h instead of a plain > comparison to avoid
any issues with the time wrapping on a system that has been sitting in
u-boot for a long time.

Signed-off-by: Chris Packham <judge.packham@gmail.com>
Reviewed-by: Stefan Roese <sr@denx.de>

diff --git a/drivers/watchdog/wdt-uclass.c b/drivers/watchdog/wdt-uclass.c
index cf1c527..d9e4dc7 100644 (file)
--- a/drivers/watchdog/wdt-uclass.c
+++ b/drivers/watchdog/wdt-uclass.c
@@ -7,6 +7,7 @@
 #include <dm.h>
 #include <errno.h>
 #include <hang.h>
+#include <time.h>
 #include <wdt.h>
 #include <dm/device-internal.h>
 #include <dm/lists.h>
@@ -83,7 +84,7 @@ void watchdog_reset(void)
 
        /* Do not reset the watchdog too often */
        now = get_timer(0);
-       if (now > next_reset) {
+       if (time_after(now, next_reset)) {
                next_reset = now + 1000;        /* reset every 1000ms */
                wdt_reset(gd->watchdog_dev);
        }