Re: [PATCH edk2-platforms] [PATCH v3 2/9] Platform/NXP : Add support for Watchdog driver

[Leif Lindholm <leif.lindholm@linaro.org>]

Mike, Liming, as MdePkg mainteiners - one question below:

On Mon, Nov 27, 2017 at 04:21:50PM +0530, Meenakshi Aggarwal wrote:
> diff --git a/Platform/NXP/Drivers/WatchDog/WatchDog.c b/Platform/NXP/Drivers/WatchDog/WatchDog.c
> new file mode 100644
> index 0000000..a9c70ef
> --- /dev/null
> +++ b/Platform/NXP/Drivers/WatchDog/WatchDog.c
> @@ -0,0 +1,421 @@

...

> +/**
> +  This function registers the handler NotifyFunction so it is called every time
> +  the watchdog timer expires.  It also passes the amount of time since the last
> +  handler call to the NotifyFunction.
> +  If NotifyFunction is not NULL and a handler is not already registered,
> +  then the new handler is registered and EFI_SUCCESS is returned.
> +  If NotifyFunction is NULL, and a handler is already registered,
> +  then that handler is unregistered.
> +  If an attempt is made to register a handler when a handler is already registered,
> +  then EFI_ALREADY_STARTED is returned.
> +  If an attempt is made to unregister a handler when a handler is not registered,
> +  then EFI_INVALID_PARAMETER is returned.
> +
> +  @param  This             The EFI_TIMER_ARCH_PROTOCOL instance.
> +  @param  NotifyFunction   The function to call when a timer interrupt fires. This
> +                           function executes at TPL_HIGH_LEVEL. The DXE Core will
> +                           register a handler for the timer interrupt, so it can know
> +                           how much time has passed. This information is used to
> +                           signal timer based events. NULL will unregister the handler.
> +
> +  @retval EFI_SUCCESS           The watchdog timer handler was registered.
> +  @retval EFI_ALREADY_STARTED   NotifyFunction is not NULL, and a handler is already
> +                                registered.
> +  @retval EFI_INVALID_PARAMETER NotifyFunction is NULL, and a handler was not
> +                                previously registered.
> +
> +**/
> +STATIC
> +EFI_STATUS
> +EFIAPI
> +WdogRegisterHandler (
> +  IN EFI_WATCHDOG_TIMER_ARCH_PROTOCOL   *This,
> +  IN EFI_WATCHDOG_TIMER_NOTIFY          NotifyFunction
> +  )
> +{
> +  // ERROR: This function is not supported.
> +  // The hardware watchdog will reset the board
> +  return EFI_INVALID_PARAMETER;

Michael, Liming - what's your take on this?

Is EFI_WATCHDOG_TIMER_ARCH_PROTOCOL suitable for use with a pure-hw
watchdog such as this?

If so, what would be a suitable return code here?
EFI_INVALID_PARAMETER does not look ideal.

/
    Leif