1. Patchew
  2. linux
  3. View series

[PATCH] watchdog: arm_smc_wdt: get wdt status through SMCWD_GET_TIMELEFT

Antonio Borneo posted 1 patch 7 months ago
There is a newer version of this series
drivers/watchdog/arm_smc_wdt.c | 18 +++++++++++++++---
1 file changed, 15 insertions(+), 3 deletions(-)
[PATCH] watchdog: arm_smc_wdt: get wdt status through SMCWD_GET_TIMELEFT
Posted by Antonio Borneo 7 months ago 
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].

If CONFIG_WATCHDOG_HANDLE_BOOT_ENABLED is set, 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>
---
 drivers/watchdog/arm_smc_wdt.c | 18 +++++++++++++++---
 1 file changed, 15 insertions(+), 3 deletions(-)

diff --git a/drivers/watchdog/arm_smc_wdt.c b/drivers/watchdog/arm_smc_wdt.c
index 8f3d0c3a005fb..f1268f43327ea 100644
--- a/drivers/watchdog/arm_smc_wdt.c
+++ b/drivers/watchdog/arm_smc_wdt.c
@@ -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 +133,20 @@ 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:
+		if (IS_ENABLED(CONFIG_WATCHDOG_HANDLE_BOOT_ENABLED))
+			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;

base-commit: a5806cd506af5a7c19bcd596e4708b5c464bfd21
-- 
2.34.1
Re: [PATCH] watchdog: arm_smc_wdt: get wdt status through SMCWD_GET_TIMELEFT
Posted by Guenter Roeck 7 months ago 
On 5/19/25 10:00, Antonio Borneo wrote:
> 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].
> 
> If CONFIG_WATCHDOG_HANDLE_BOOT_ENABLED is set, 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>
> ---
>   drivers/watchdog/arm_smc_wdt.c | 18 +++++++++++++++---
>   1 file changed, 15 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/watchdog/arm_smc_wdt.c b/drivers/watchdog/arm_smc_wdt.c
> index 8f3d0c3a005fb..f1268f43327ea 100644
> --- a/drivers/watchdog/arm_smc_wdt.c
> +++ b/drivers/watchdog/arm_smc_wdt.c
> @@ -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 +133,20 @@ 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:
> +		if (IS_ENABLED(CONFIG_WATCHDOG_HANDLE_BOOT_ENABLED))
> +			set_bit(WDOG_HW_RUNNING, &wdd->status);

This is the wrong use of this configuration option. It is only needed
in a driver if the watchdog status can not be read from hardware.
That is not the case here. Worse, using it in a driver like this
overrides the watchdog core module parameter "handle_boot_enabled".

Guenter

> +		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;
> 
> base-commit: a5806cd506af5a7c19bcd596e4708b5c464bfd21
Re: [PATCH] watchdog: arm_smc_wdt: get wdt status through SMCWD_GET_TIMELEFT
Posted by Julius Werner 7 months ago 
I don't really know about the issue Guenter mentioned, but otherwise,
from the driver's side this looks good to me.

Reviewed-by: Julius Werner <jwerner@chromium.org>

On Mon, May 19, 2025 at 10:58 AM Guenter Roeck <linux@roeck-us.net> wrote:
>
> On 5/19/25 10:00, Antonio Borneo wrote:
> > 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].
> >
> > If CONFIG_WATCHDOG_HANDLE_BOOT_ENABLED is set, 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>
> > ---
> >   drivers/watchdog/arm_smc_wdt.c | 18 +++++++++++++++---
> >   1 file changed, 15 insertions(+), 3 deletions(-)
> >
> > diff --git a/drivers/watchdog/arm_smc_wdt.c b/drivers/watchdog/arm_smc_wdt.c
> > index 8f3d0c3a005fb..f1268f43327ea 100644
> > --- a/drivers/watchdog/arm_smc_wdt.c
> > +++ b/drivers/watchdog/arm_smc_wdt.c
> > @@ -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 +133,20 @@ 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:
> > +             if (IS_ENABLED(CONFIG_WATCHDOG_HANDLE_BOOT_ENABLED))
> > +                     set_bit(WDOG_HW_RUNNING, &wdd->status);
>
> This is the wrong use of this configuration option. It is only needed
> in a driver if the watchdog status can not be read from hardware.
> That is not the case here. Worse, using it in a driver like this
> overrides the watchdog core module parameter "handle_boot_enabled".
>
> Guenter
>
> > +             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;
> >
> > base-commit: a5806cd506af5a7c19bcd596e4708b5c464bfd21
>
Re: [PATCH] watchdog: arm_smc_wdt: get wdt status through SMCWD_GET_TIMELEFT
Posted by Guenter Roeck 7 months ago 
On 5/19/25 17:12, Julius Werner wrote:
> I don't really know about the issue Guenter mentioned, but otherwise,
> from the driver's side this looks good to me.
> 

It should just be
	set_bit(WDOG_HW_RUNNING, &wdd->status);

There should be no dependency on CONFIG_WATCHDOG_HANDLE_BOOT_ENABLED.

Guenter
	
> Reviewed-by: Julius Werner <jwerner@chromium.org>
> 
> On Mon, May 19, 2025 at 10:58 AM Guenter Roeck <linux@roeck-us.net> wrote:
>>
>> On 5/19/25 10:00, Antonio Borneo wrote:
>>> 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].
>>>
>>> If CONFIG_WATCHDOG_HANDLE_BOOT_ENABLED is set, 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>
>>> ---
>>>    drivers/watchdog/arm_smc_wdt.c | 18 +++++++++++++++---
>>>    1 file changed, 15 insertions(+), 3 deletions(-)
>>>
>>> diff --git a/drivers/watchdog/arm_smc_wdt.c b/drivers/watchdog/arm_smc_wdt.c
>>> index 8f3d0c3a005fb..f1268f43327ea 100644
>>> --- a/drivers/watchdog/arm_smc_wdt.c
>>> +++ b/drivers/watchdog/arm_smc_wdt.c
>>> @@ -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 +133,20 @@ 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:
>>> +             if (IS_ENABLED(CONFIG_WATCHDOG_HANDLE_BOOT_ENABLED))
>>> +                     set_bit(WDOG_HW_RUNNING, &wdd->status);
>>
>> This is the wrong use of this configuration option. It is only needed
>> in a driver if the watchdog status can not be read from hardware.
>> That is not the case here. Worse, using it in a driver like this
>> overrides the watchdog core module parameter "handle_boot_enabled".
>>
>> Guenter
>>
>>> +             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;
>>>
>>> base-commit: a5806cd506af5a7c19bcd596e4708b5c464bfd21
>>
Re: [PATCH] watchdog: arm_smc_wdt: get wdt status through SMCWD_GET_TIMELEFT
Posted by Antonio Borneo 7 months ago 
On Mon, 2025-05-19 at 18:13 -0700, Guenter Roeck wrote:
> On 5/19/25 17:12, Julius Werner wrote:
> > I don't really know about the issue Guenter mentioned, but otherwise,
> > from the driver's side this looks good to me.
> > 
> 
> It should just be
>         set_bit(WDOG_HW_RUNNING, &wdd->status);
> 
> There should be no dependency on CONFIG_WATCHDOG_HANDLE_BOOT_ENABLED.
> 
> Guenter
> 

Thanks for the review!
I agree on Guenter's comment and I will send a V2 shortly.

Regards
Antonio
[PATCH v2] watchdog: arm_smc_wdt: get wdt status through SMCWD_GET_TIMELEFT
Posted by Antonio Borneo 7 months ago 
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>
---
 drivers/watchdog/arm_smc_wdt.c | 17 ++++++++++++++---
 1 file changed, 14 insertions(+), 3 deletions(-)

diff --git a/drivers/watchdog/arm_smc_wdt.c b/drivers/watchdog/arm_smc_wdt.c
index 8f3d0c3a005fb..bbba23ace7b85 100644
--- a/drivers/watchdog/arm_smc_wdt.c
+++ b/drivers/watchdog/arm_smc_wdt.c
@@ -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;

base-commit: a5806cd506af5a7c19bcd596e4708b5c464bfd21
-- 
2.34.1
Re: [PATCH v2] watchdog: arm_smc_wdt: get wdt status through SMCWD_GET_TIMELEFT
Posted by Guenter Roeck 7 months ago 
On 5/20/25 01:59, Antonio Borneo wrote:
> 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>

> ---
>   drivers/watchdog/arm_smc_wdt.c | 17 ++++++++++++++---
>   1 file changed, 14 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/watchdog/arm_smc_wdt.c b/drivers/watchdog/arm_smc_wdt.c
> index 8f3d0c3a005fb..bbba23ace7b85 100644
> --- a/drivers/watchdog/arm_smc_wdt.c
> +++ b/drivers/watchdog/arm_smc_wdt.c
> @@ -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;
> 
> base-commit: a5806cd506af5a7c19bcd596e4708b5c464bfd21

Patchew 2.1-devel-b67e4c2

© 2016 - 2025 Red Hat, Inc.