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/*
* arch/arm/kernel/topology.c
*
* Copyright (C) 2011 Linaro Limited.
* Written by: Vincent Guittot
*
* based on arch/sh/kernel/topology.c
*
* This file is subject to the terms and conditions of the GNU General Public
* License. See the file "COPYING" in the main directory of this archive
* for more details.
*/
#include <linux/cpu.h>
#include <linux/cpumask.h>
#include <linux/init.h>
#include <linux/percpu.h>
#include <linux/node.h>
#include <linux/nodemask.h>
#include <linux/sched.h>
#include <asm/cputype.h>
#include <asm/topology.h>
#define MPIDR_SMP_BITMASK (0x3 << 30)
#define MPIDR_SMP_VALUE (0x2 << 30)
#define MPIDR_MT_BITMASK (0x1 << 24)
/*
* These masks reflect the current use of the affinity levels.
* The affinity level can be up to 16 bits according to ARM ARM
*/
#define MPIDR_LEVEL0_MASK 0x3
#define MPIDR_LEVEL0_SHIFT 0
#define MPIDR_LEVEL1_MASK 0xF
#define MPIDR_LEVEL1_SHIFT 8
#define MPIDR_LEVEL2_MASK 0xFF
#define MPIDR_LEVEL2_SHIFT 16
struct cputopo_arm cpu_topology[NR_CPUS];
const struct cpumask *cpu_coregroup_mask(unsigned int cpu)
{
return &cpu_topology[cpu].core_sibling;
}
/*
* store_cpu_topology is called at boot when only one cpu is running
* and with the mutex cpu_hotplug.lock locked, when several cpus have booted,
* which prevents simultaneous write access to cpu_topology array
*/
void store_cpu_topology(unsigned int cpuid)
{
struct cputopo_arm *cpuid_topo = &cpu_topology[cpuid];
unsigned int mpidr;
unsigned int cpu;
/* If the cpu topology has been already set, just return */
if (cpuid_topo->core_id != -1)
return;
mpidr = read_cpuid_mpidr();
/* create cpu topology mapping */
if ((mpidr & MPIDR_SMP_BITMASK) == MPIDR_SMP_VALUE) {
/*
* This is a multiprocessor system
* multiprocessor format & multiprocessor mode field are set
*/
if (mpidr & MPIDR_MT_BITMASK) {
/* core performance interdependency */
cpuid_topo->thread_id = (mpidr >> MPIDR_LEVEL0_SHIFT)
& MPIDR_LEVEL0_MASK;
cpuid_topo->core_id = (mpidr >> MPIDR_LEVEL1_SHIFT)
& MPIDR_LEVEL1_MASK;
cpuid_topo->socket_id = (mpidr >> MPIDR_LEVEL2_SHIFT)
& MPIDR_LEVEL2_MASK;
} else {
/* largely independent cores */
cpuid_topo->thread_id = -1;
cpuid_topo->core_id = (mpidr >> MPIDR_LEVEL0_SHIFT)
& MPIDR_LEVEL0_MASK;
cpuid_topo->socket_id = (mpidr >> MPIDR_LEVEL1_SHIFT)
& MPIDR_LEVEL1_MASK;
}
} else {
/*
* This is an uniprocessor system
* we are in multiprocessor format but uniprocessor system
* or in the old uniprocessor format
*/
cpuid_topo->thread_id = -1;
cpuid_topo->core_id = 0;
cpuid_topo->socket_id = -1;
}
/* update core and thread sibling masks */
for_each_possible_cpu(cpu) {
struct cputopo_arm *cpu_topo = &cpu_topology[cpu];
if (cpuid_topo->socket_id == cpu_topo->socket_id) {
cpumask_set_cpu(cpuid, &cpu_topo->core_sibling);
if (cpu != cpuid)
cpumask_set_cpu(cpu,
&cpuid_topo->core_sibling);
if (cpuid_topo->core_id == cpu_topo->core_id) {
cpumask_set_cpu(cpuid,
&cpu_topo->thread_sibling);
if (cpu != cpuid)
cpumask_set_cpu(cpu,
&cpuid_topo->thread_sibling);
}
}
}
smp_wmb();
printk(KERN_INFO "CPU%u: thread %d, cpu %d, socket %d, mpidr %x\n",
cpuid, cpu_topology[cpuid].thread_id,
cpu_topology[cpuid].core_id,
cpu_topology[cpuid].socket_id, mpidr);
}
/*
* init_cpu_topology is called at boot when only one cpu is running
* which prevent simultaneous write access to cpu_topology array
*/
void init_cpu_topology(void)
{
unsigned int cpu;
/* init core mask */
for_each_possible_cpu(cpu) {
struct cputopo_arm *cpu_topo = &(cpu_topology[cpu]);
cpu_topo->thread_id = -1;
cpu_topo->core_id = -1;
cpu_topo->socket_id = -1;
cpumask_clear(&cpu_topo->core_sibling);
cpumask_clear(&cpu_topo->thread_sibling);
}
smp_wmb();
}
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