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ARM: kernel: add logical mappings look-up

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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>
This commit is contained in:
Lorenzo Pieralisi 2011-11-17 17:36:24 +00:00
parent 5587164eea
commit 7f124aaf01
1 changed files with 17 additions and 0 deletions
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17
arch/arm/include/asm/smp_plat.h
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@ -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