1/*
  2 * arch/arm/kernel/topology.c
  3 *
  4 * Copyright (C) 2011 Linaro Limited.
  5 * Written by: Vincent Guittot
  6 *
  7 * based on arch/sh/kernel/topology.c
  8 *
  9 * This file is subject to the terms and conditions of the GNU General Public
 10 * License.  See the file "COPYING" in the main directory of this archive
 11 * for more details.
 12 */
 13
 14#include <linux/cpu.h>
 15#include <linux/cpumask.h>
 16#include <linux/init.h>
 17#include <linux/percpu.h>
 18#include <linux/node.h>
 19#include <linux/nodemask.h>
 20#include <linux/sched.h>
 21
 22#include <asm/cputype.h>
 23#include <asm/topology.h>
 24
 25#define MPIDR_SMP_BITMASK (0x3 << 30)
 26#define MPIDR_SMP_VALUE (0x2 << 30)
 27
 28#define MPIDR_MT_BITMASK (0x1 << 24)
 29
 30/*
 31 * These masks reflect the current use of the affinity levels.
 32 * The affinity level can be up to 16 bits according to ARM ARM
 33 */
 34
 35#define MPIDR_LEVEL0_MASK 0x3
 36#define MPIDR_LEVEL0_SHIFT 0
 37
 38#define MPIDR_LEVEL1_MASK 0xF
 39#define MPIDR_LEVEL1_SHIFT 8
 40
 41#define MPIDR_LEVEL2_MASK 0xFF
 42#define MPIDR_LEVEL2_SHIFT 16
 43
 44struct cputopo_arm cpu_topology[NR_CPUS];
 45
 46const struct cpumask *cpu_coregroup_mask(int cpu)
 47{
 48	return &cpu_topology[cpu].core_sibling;
 49}
 50
 51/*
 52 * store_cpu_topology is called at boot when only one cpu is running
 53 * and with the mutex cpu_hotplug.lock locked, when several cpus have booted,
 54 * which prevents simultaneous write access to cpu_topology array
 55 */
 56void store_cpu_topology(unsigned int cpuid)
 57{
 58	struct cputopo_arm *cpuid_topo = &cpu_topology[cpuid];
 59	unsigned int mpidr;
 60	unsigned int cpu;
 61
 62	/* If the cpu topology has been already set, just return */
 63	if (cpuid_topo->core_id != -1)
 64		return;
 65
 66	mpidr = read_cpuid_mpidr();
 67
 68	/* create cpu topology mapping */
 69	if ((mpidr & MPIDR_SMP_BITMASK) == MPIDR_SMP_VALUE) {
 70		/*
 71		 * This is a multiprocessor system
 72		 * multiprocessor format & multiprocessor mode field are set
 73		 */
 74
 75		if (mpidr & MPIDR_MT_BITMASK) {
 76			/* core performance interdependency */
 77			cpuid_topo->thread_id = (mpidr >> MPIDR_LEVEL0_SHIFT)
 78				& MPIDR_LEVEL0_MASK;
 79			cpuid_topo->core_id = (mpidr >> MPIDR_LEVEL1_SHIFT)
 80				& MPIDR_LEVEL1_MASK;
 81			cpuid_topo->socket_id = (mpidr >> MPIDR_LEVEL2_SHIFT)
 82				& MPIDR_LEVEL2_MASK;
 83		} else {
 84			/* largely independent cores */
 85			cpuid_topo->thread_id = -1;
 86			cpuid_topo->core_id = (mpidr >> MPIDR_LEVEL0_SHIFT)
 87				& MPIDR_LEVEL0_MASK;
 88			cpuid_topo->socket_id = (mpidr >> MPIDR_LEVEL1_SHIFT)
 89				& MPIDR_LEVEL1_MASK;
 90		}
 91	} else {
 92		/*
 93		 * This is an uniprocessor system
 94		 * we are in multiprocessor format but uniprocessor system
 95		 * or in the old uniprocessor format
 96		 */
 97		cpuid_topo->thread_id = -1;
 98		cpuid_topo->core_id = 0;
 99		cpuid_topo->socket_id = -1;
100	}
101
102	/* update core and thread sibling masks */
103	for_each_possible_cpu(cpu) {
104		struct cputopo_arm *cpu_topo = &cpu_topology[cpu];
105
106		if (cpuid_topo->socket_id == cpu_topo->socket_id) {
107			cpumask_set_cpu(cpuid, &cpu_topo->core_sibling);
108			if (cpu != cpuid)
109				cpumask_set_cpu(cpu,
110					&cpuid_topo->core_sibling);
111
112			if (cpuid_topo->core_id == cpu_topo->core_id) {
113				cpumask_set_cpu(cpuid,
114					&cpu_topo->thread_sibling);
115				if (cpu != cpuid)
116					cpumask_set_cpu(cpu,
117						&cpuid_topo->thread_sibling);
118			}
119		}
120	}
121	smp_wmb();
122
123	printk(KERN_INFO "CPU%u: thread %d, cpu %d, socket %d, mpidr %x\n",
124		cpuid, cpu_topology[cpuid].thread_id,
125		cpu_topology[cpuid].core_id,
126		cpu_topology[cpuid].socket_id, mpidr);
127}
128
129/*
130 * init_cpu_topology is called at boot when only one cpu is running
131 * which prevent simultaneous write access to cpu_topology array
132 */
133void init_cpu_topology(void)
134{
135	unsigned int cpu;
136
137	/* init core mask */
138	for_each_possible_cpu(cpu) {
139		struct cputopo_arm *cpu_topo = &(cpu_topology[cpu]);
140
141		cpu_topo->thread_id = -1;
142		cpu_topo->core_id =  -1;
143		cpu_topo->socket_id = -1;
144		cpumask_clear(&cpu_topo->core_sibling);
145		cpumask_clear(&cpu_topo->thread_sibling);
146	}
147	smp_wmb();
148}