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watchdog: arm_smc_wdt: get wdt status through SMCWD_GET_TIMELEFT

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The optional SMCWD_GET_TIMELEFT command can be used to detect if
the watchdog has already been started.
See the implementation in OP-TEE secure OS [1].

At probe time, check if the watchdog is already started and then
set WDOG_HW_RUNNING in the watchdog status. This will cause the
watchdog framework to ping the watchdog until a userspace watchdog
daemon takes over the control.

Link: https://github.com/OP-TEE/optee_os/commit/a7f2d4bd8632 [1]

Signed-off-by: Antonio Borneo <antonio.borneo@foss.st.com>
Reviewed-by: Guenter Roeck <linux@roeck-us.net>
Link: https://lore.kernel.org/r/20250520085952.210723-1-antonio.borneo@foss.st.com
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Wim Van Sebroeck <wim@linux-watchdog.org>
This commit is contained in:
Antonio Borneo
2025-05-20 10:59:52 +02:00
committed by Wim Van Sebroeck
parent 27a46a0f08
commit cc0df5eba1
1 changed files with 14 additions and 3 deletions
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17
drivers/watchdog/arm_smc_wdt.c
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@@ -46,6 +46,8 @@ static int smcwd_call(struct watchdog_device *wdd, enum smcwd_call call,
return -ENODEV;
if (res->a0 == PSCI_RET_INVALID_PARAMS)
return -EINVAL;
if (res->a0 == PSCI_RET_DISABLED)
return -ENODATA;
if (res->a0 != PSCI_RET_SUCCESS)
return -EIO;
return 0;
@@ -131,10 +133,19 @@ static int smcwd_probe(struct platform_device *pdev)
wdd->info = &smcwd_info;
/* get_timeleft is optional */
if (smcwd_call(wdd, SMCWD_GET_TIMELEFT, 0, NULL))
wdd->ops = &smcwd_ops;
else
err = smcwd_call(wdd, SMCWD_GET_TIMELEFT, 0, NULL);
switch (err) {
case 0:
set_bit(WDOG_HW_RUNNING, &wdd->status);
fallthrough;
case -ENODATA:
wdd->ops = &smcwd_timeleft_ops;
break;
default:
wdd->ops = &smcwd_ops;
break;
}
wdd->timeout = res.a2;
wdd->max_timeout = res.a2;
wdd->min_timeout = res.a1;