From mboxrd@z Thu Jan  1 00:00:00 1970
From: Nicolas Pitre <nicolas.pitre@linaro.org>
Subject: Re: [PATCH v3 4/5] ARM: kernel: add logical mappings look-up
Date: Sun, 18 Nov 2012 22:14:53 -0500 (EST)
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To: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
Cc: Mark Rutland <Mark.Rutland@arm.com>, Dave Martin <dave.martin@linaro.org>, Kukjin Kim <kgene.kim@samsung.com>, Russell King <linux@arm.linux.org.uk>, Pawel Moll <Pawel.Moll@arm.com>, Stephen Warren <swarren@wwwdotorg.org>, Tony Lindgren <tony@atomide.com>, Catalin Marinas <Catalin.Marinas@arm.com>, devicetree-discuss@lists.ozlabs.org, Will Deacon <will.deacon@arm.com>, Amit Kucheria <amit.kucheria@linaro.org>, Grant Likely <grant.likely@secretlab.ca>, Rob Herring <rob.herring@calxeda.com>, Benjamin Herrenschmidt <benh@kernel.crashing.org>, David Brown <davidb@codeaurora.org>, Magnus Damm <magnus.damm@gmail.com>, linux-arm-kernel@lists.infradead.org
List-Id: devicetree@vger.kernel.org

On Thu, 15 Nov 2012, Lorenzo Pieralisi wrote:

> In ARM SMP systems the MPIDR register ([23:0] bits) is used to uniquely
> identify CPUs.
> 
> In order to retrieve the logical CPU index corresponding to a given
> MPIDR value and guarantee a consistent translation throughout the kernel,
> this patch adds a look-up based on the MPIDR[23:0] so that kernel subsystems
> can use it whenever the logical cpu index corresponding to a given MPIDR
> value is needed.
> 
> Signed-off-by: Lorenzo Pieralisi <lorenzo.pieralisi@arm.com>
> Acked-by: Will Deacon <will.deacon@arm.com>

Acked-by: Nicolas Pitre <nico@linaro.org>

> ---
>  arch/arm/include/asm/smp_plat.h | 17 +++++++++++++++++
>  1 file changed, 17 insertions(+)
> 
> diff --git a/arch/arm/include/asm/smp_plat.h b/arch/arm/include/asm/smp_plat.h
> index 558d6c8..aaa61b6 100644
> --- a/arch/arm/include/asm/smp_plat.h
> +++ b/arch/arm/include/asm/smp_plat.h
> @@ -5,6 +5,9 @@
>  #ifndef __ASMARM_SMP_PLAT_H
>  #define __ASMARM_SMP_PLAT_H
>  
> +#include <linux/cpumask.h>
> +#include <linux/err.h>
> +
>  #include <asm/cputype.h>
>  
>  /*
> @@ -48,5 +51,19 @@ static inline int cache_ops_need_broadcast(void)
>   */
>  extern int __cpu_logical_map[];
>  #define cpu_logical_map(cpu)	__cpu_logical_map[cpu]
> +/*
> + * Retrieve logical cpu index corresponding to a given MPIDR[23:0]
> + *  - mpidr: MPIDR[23:0] to be used for the look-up
> + *
> + * Returns the cpu logical index or -EINVAL on look-up error
> + */
> +static inline int get_logical_index(u32 mpidr)
> +{
> +	int cpu;
> +	for (cpu = 0; cpu < nr_cpu_ids; cpu++)
> +		if (cpu_logical_map(cpu) == mpidr)
> +			return cpu;
> +	return -EINVAL;
> +}
>  
>  #endif
> -- 
> 1.7.12
> 
>