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watchdog: honour hw_margin_ms DT property

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Some watchdog devices, e.g. external gpio-triggered ones, must be
reset more often than once per second, which means that the current
rate-limiting logic in watchdog_reset() fails to keep the board alive.

gpio-wdt.txt in the linux source tree defines a "hw_margin_ms"
property used to specifiy the maximum time allowed between resetting
the device. Allow any watchdog device to specify such a property, and
then use a reset period of one quarter of that. We keep the current
default of resetting once every 1000ms.

Signed-off-by: Rasmus Villemoes <rasmus.villemoes@prevas.dk>
Reviewed-by: Stefan Roese <sr@denx.de>
This commit is contained in:
Rasmus Villemoes 2020-03-13 17:04:58 +01:00 committed by Stefan Roese
parent b4d9452c44
commit 40d7f3c8d1
1 changed files with 10 additions and 1 deletions
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11
drivers/watchdog/wdt-uclass.c
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@ -16,6 +16,12 @@ DECLARE_GLOBAL_DATA_PTR;
#define WATCHDOG_TIMEOUT_SECS (CONFIG_WATCHDOG_TIMEOUT_MSECS / 1000)
/*
* Reset every 1000ms, or however often is required as indicated by a
* hw_margin_ms property.
*/
static ulong reset_period = 1000;
int initr_watchdog(void)
{
u32 timeout = WATCHDOG_TIMEOUT_SECS;
@ -37,6 +43,9 @@ int initr_watchdog(void)
if (CONFIG_IS_ENABLED(OF_CONTROL) && !CONFIG_IS_ENABLED(OF_PLATDATA)) {
timeout = dev_read_u32_default(gd->watchdog_dev, "timeout-sec",
WATCHDOG_TIMEOUT_SECS);
reset_period = dev_read_u32_default(gd->watchdog_dev,
"hw_margin_ms",
4 * reset_period) / 4;
}
wdt_start(gd->watchdog_dev, timeout * 1000, 0);
@ -118,7 +127,7 @@ void watchdog_reset(void)
/* Do not reset the watchdog too often */
now = get_timer(0);
if (time_after(now, next_reset)) {
next_reset = now + 1000; /* reset every 1000ms */
next_reset = now + reset_period;
wdt_reset(gd->watchdog_dev);
}
}