On Wed, Oct 11, 2017 at 10:03:01AM +0200, Geert Uytterhoeven wrote:
> PSCI support may be disabled at build time (by configuration) or at
> run-time (PSCI firmware not present). While CONFIG_ARM_PSCI_FW can be
> used to check for build time enablement, there is currently no simple
> way to check if PSCI is actually available and used.
>
> Hence add a helper function to check if PSCI is available.
Hi Geert,
excuse us the delay in responding. I think it would be better if the
check just carries out a DT/ACPI matching check rather than being based
on PSCI ops initialization but before doing that I would like first to
understand what this function can be actually used for (ie I do not
think the usage in the PSCI checker is relevant to this discussion).
Thanks,
Lorenzo
> This is useful for e.g. drivers that are used on platforms with and
> without PSCI. Such drivers may need to take provisions for proper
> operation when PSCI is used, and/or to implement functionality that is
> usually provided by PSCI.
>
> Signed-off-by: Geert Uytterhoeven <geert+renesas@xxxxxxxxx>
> ---
> drivers/firmware/psci.c | 5 +++++
> include/linux/psci.h | 2 ++
> 2 files changed, 7 insertions(+)
>
> diff --git a/drivers/firmware/psci.c b/drivers/firmware/psci.c
> index da469c972b503f83..a3a11e2d8ffffaaa 100644
> --- a/drivers/firmware/psci.c
> +++ b/drivers/firmware/psci.c
> @@ -670,6 +670,11 @@ int __init psci_dt_init(void)
> return init_fn(np);
> }
>
> +bool psci_is_available(void)
> +{
> + return psci_ops.cpu_off && psci_ops.cpu_on && psci_ops.cpu_suspend;
> +}
> +
> #ifdef CONFIG_ACPI
> /*
> * We use PSCI 0.2+ when ACPI is deployed on ARM64 and it's
> diff --git a/include/linux/psci.h b/include/linux/psci.h
> index bdea1cb5e1db142b..2bdee325aeb80cf6 100644
> --- a/include/linux/psci.h
> +++ b/include/linux/psci.h
> @@ -39,8 +39,10 @@ extern struct psci_operations psci_ops;
>
> #if defined(CONFIG_ARM_PSCI_FW)
> int __init psci_dt_init(void);
> +bool psci_is_available(void);
> #else
> static inline int psci_dt_init(void) { return 0; }
> +static inline bool psci_is_available(void) { return false; }
> #endif
>
> #if defined(CONFIG_ARM_PSCI_FW) && defined(CONFIG_ACPI)
