[PATCH 1/3] arm64: Add cpuidle context save/restore helpers

[Lorenzo Pieralisi]

On Tue, Jun 08, 2021 at 06:27:13PM +0100, Marc Zyngier wrote:
> As we need to start doing some additional work on all idle
> paths, let's introduce a set of macros that will perform
> the work related to the GICv3 pseudo-NMI idle entry exit.
> 
> Stubs are introduced to 32bit ARM for compatibility.
> As these helpers are currently unused, the is no functional

s/the/there

> change.
> 
> Signed-off-by: Marc Zyngier <maz at kernel.org>
> ---
>  arch/arm/include/asm/cpuidle.h   |  5 +++++
>  arch/arm64/include/asm/cpuidle.h | 35 ++++++++++++++++++++++++++++++++
>  2 files changed, 40 insertions(+)
> 
> diff --git a/arch/arm/include/asm/cpuidle.h b/arch/arm/include/asm/cpuidle.h
> index 0d67ed682e07..1e0b8da12d96 100644
> --- a/arch/arm/include/asm/cpuidle.h
> +++ b/arch/arm/include/asm/cpuidle.h
> @@ -49,4 +49,9 @@ extern int arm_cpuidle_suspend(int index);
>  
>  extern int arm_cpuidle_init(int cpu);
>  
> +struct arm_cpuidle_context { };
> +
> +#define arm_cpuidle_save_context(c)	(void)c
> +#define arm_cpuidle_restore_context(c)	(void)c
> +
>  #endif
> diff --git a/arch/arm64/include/asm/cpuidle.h b/arch/arm64/include/asm/cpuidle.h
> index 3c5ddb429ea2..53adad0a5c7e 100644
> --- a/arch/arm64/include/asm/cpuidle.h
> +++ b/arch/arm64/include/asm/cpuidle.h
> @@ -18,4 +18,39 @@ static inline int arm_cpuidle_suspend(int index)
>  	return -EOPNOTSUPP;
>  }
>  #endif
> +
> +#ifdef CONFIG_ARM64_PSEUDO_NMI
> +#include <asm/arch_gicv3.h>
> +
> +struct arm_cpuidle_context {
> +	unsigned long pmr;
> +	unsigned long daif_bits;
> +};
> +
> +#define arm_cpuidle_save_context(__c)					\
> +	do {								\
> +		struct arm_cpuidle_context *c = __c;			\
> +		if (system_uses_irq_prio_masking()) {			\
> +			c->daif_bits = read_sysreg(daif);		\
> +			write_sysreg(c->daif_bits | PSR_I_BIT | PSR_F_BIT, \
> +				     daif);				\
> +			c->pmr = gic_read_pmr();			\
> +			gic_write_pmr(GIC_PRIO_IRQON | GIC_PRIO_PSR_I_SET); \
> +		}							\
> +	} while (0)
> +
> +#define arm_cpuidle_restore_context(__c)				\
> +	do {								\
> +		struct arm_cpuidle_context *c = __c;			\
> +		if (system_uses_irq_prio_masking()) {			\
> +			gic_write_pmr(c->pmr);				\
> +			write_sysreg(c->daif_bits, daif);		\
> +		}							\
> +	} while (0)
> +#else
> +struct arm_cpuidle_context { };
> +
> +#define arm_cpuidle_save_context(c)	(void)c
> +#define arm_cpuidle_restore_context(c)	(void)c
> +#endif
>  #endif

It looks good to me - maybe I would define it irq_context for clarity
but that's just a naming convention.

Reviewed-by: Lorenzo Pieralisi <lorenzo.pieralisi at arm.com>