[PATCH v3 4/5] ARM: kernel: add logical mappings look-up
Nicolas Pitre
nicolas.pitre at linaro.org
Sun Nov 18 22:14:53 EST 2012
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 at arm.com>
> Acked-by: Will Deacon <will.deacon at arm.com>
Acked-by: Nicolas Pitre <nico at 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
>
>
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