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SubjectRe: [RFC PATCH 23/33] irqchip/gic-v3-its: Add VPENDBASER/VPROPBASER accessors
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Hi Marc,


On 01/17/2017 04:20 AM, Marc Zyngier wrote:
> V{PEND,PROP}BASER being 64bit registers, they need some ad-hoc
> accessors on 32bit, specially given that VPENDBASER contains
> a Valid bit, making the access a bit convoluted.
>
> Signed-off-by: Marc Zyngier <marc.zyngier@arm.com>
> ---
> arch/arm/include/asm/arch_gicv3.h | 28 ++++++++++++++++++++++++++++
> arch/arm64/include/asm/arch_gicv3.h | 5 +++++
> 2 files changed, 33 insertions(+)
>
> diff --git a/arch/arm/include/asm/arch_gicv3.h
> b/arch/arm/include/asm/arch_gicv3.h
> index 2747590..3f18832 100644
> --- a/arch/arm/include/asm/arch_gicv3.h
> +++ b/arch/arm/include/asm/arch_gicv3.h
> @@ -291,5 +291,33 @@ static inline u64 __gic_readq_nonatomic(const
> volatile void __iomem *addr)
> */
> #define gits_write_cwriter(v, c) __gic_writeq_nonatomic(v, c)
>
> +/*
> + * GITS_VPROPBASER - hi and lo bits may be accessed independently.
> + */
> +#define gits_write_vpropbaser(v, c) __gic_writeq_nonatomic(v, c)
> +
> +/*
> + * GITS_VPENDBASER - the Valid bit must be cleared before changing
> + * anything else.
> + */
> +static inline void gits_write_vpendbaser(u64 val, void * __iomem addr)
> +{
> + u32 tmp;
> +
> + tmp = readl_relaxed(addr + 4);
> + if (tmp & GICR_PENDBASER_Valid) {
> + tmp &= ~GICR_PENDBASER_Valid;
> + writel_relaxed(tmp, addr + 4);
> + }
> +
> + /*
> + * Use the fact that __gic_writeq_nonatomic writes the second
> + * half of the 64bit quantity after the first.
> + */
> + __gic_writeq_nonatomic(val, addr);
I'm not sure whether software has to check a register write pending bit
GICR_CTLR.RWP or not. GICv3 spec says, the effect of a write to
GICR_VPENDBASER register is not guaranteed to be visible throughout the
affinity hierarchy,as indicated by GICR_CTLR.RWP == 0.

--
Shanker Donthineni
Qualcomm Datacenter Technologies, Inc. as an affiliate of Qualcomm Technologies, Inc.
Qualcomm Technologies, Inc. is a member of the Code Aurora Forum, a Linux Foundation Collaborative Project.

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