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linux-sg2042/arch/arm64/kernel/topology.c

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/*
* arch/arm64/kernel/topology.c
*
* Copyright (C) 2011,2013,2014 Linaro Limited.
*
* Based on the arm32 version written by Vincent Guittot in turn 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/acpi.h>
#include <linux/arch_topology.h>
#include <linux/cacheinfo.h>
#include <linux/cpufreq.h>
#include <linux/init.h>
#include <linux/percpu.h>
#include <asm/cpu.h>
#include <asm/cputype.h>
#include <asm/topology.h>
void store_cpu_topology(unsigned int cpuid)
{
struct cpu_topology *cpuid_topo = &cpu_topology[cpuid];
u64 mpidr;
if (cpuid_topo->package_id != -1)
goto topology_populated;
mpidr = read_cpuid_mpidr();
/* Uniprocessor systems can rely on default topology values */
if (mpidr & MPIDR_UP_BITMASK)
return;
/* Create cpu topology mapping based on MPIDR. */
if (mpidr & MPIDR_MT_BITMASK) {
/* Multiprocessor system : Multi-threads per core */
cpuid_topo->thread_id = MPIDR_AFFINITY_LEVEL(mpidr, 0);
cpuid_topo->core_id = MPIDR_AFFINITY_LEVEL(mpidr, 1);
cpuid_topo->package_id = MPIDR_AFFINITY_LEVEL(mpidr, 2) |
MPIDR_AFFINITY_LEVEL(mpidr, 3) << 8;
} else {
/* Multiprocessor system : Single-thread per core */
cpuid_topo->thread_id = -1;
cpuid_topo->core_id = MPIDR_AFFINITY_LEVEL(mpidr, 0);
cpuid_topo->package_id = MPIDR_AFFINITY_LEVEL(mpidr, 1) |
MPIDR_AFFINITY_LEVEL(mpidr, 2) << 8 |
MPIDR_AFFINITY_LEVEL(mpidr, 3) << 16;
}
pr_debug("CPU%u: cluster %d core %d thread %d mpidr %#016llx\n",
cpuid, cpuid_topo->package_id, cpuid_topo->core_id,
cpuid_topo->thread_id, mpidr);
topology_populated:
update_siblings_masks(cpuid);
}
#ifdef CONFIG_ACPI
static bool __init acpi_cpu_is_threaded(int cpu)
{
int is_threaded = acpi_pptt_cpu_is_thread(cpu);
/*
* if the PPTT doesn't have thread information, assume a homogeneous
* machine and return the current CPU's thread state.
*/
if (is_threaded < 0)
is_threaded = read_cpuid_mpidr() & MPIDR_MT_BITMASK;
return !!is_threaded;
}
/*
* Propagate the topology information of the processor_topology_node tree to the
* cpu_topology array.
*/
int __init parse_acpi_topology(void)
{
int cpu, topology_id;
if (acpi_disabled)
return 0;
for_each_possible_cpu(cpu) {
int i, cache_id;
topology_id = find_acpi_cpu_topology(cpu, 0);
if (topology_id < 0)
return topology_id;
if (acpi_cpu_is_threaded(cpu)) {
cpu_topology[cpu].thread_id = topology_id;
topology_id = find_acpi_cpu_topology(cpu, 1);
cpu_topology[cpu].core_id = topology_id;
} else {
cpu_topology[cpu].thread_id = -1;
cpu_topology[cpu].core_id = topology_id;
}
topology_id = find_acpi_cpu_topology_package(cpu);
cpu_topology[cpu].package_id = topology_id;
i = acpi_find_last_cache_level(cpu);
if (i > 0) {
/*
* this is the only part of cpu_topology that has
* a direct relationship with the cache topology
*/
cache_id = find_acpi_cpu_cache_topology(cpu, i);
if (cache_id > 0)
cpu_topology[cpu].llc_id = cache_id;
}
}
return 0;
}
#endif
#ifdef CONFIG_ARM64_AMU_EXTN
#undef pr_fmt
#define pr_fmt(fmt) "AMU: " fmt
static DEFINE_PER_CPU_READ_MOSTLY(unsigned long, arch_max_freq_scale);
static DEFINE_PER_CPU(u64, arch_const_cycles_prev);
static DEFINE_PER_CPU(u64, arch_core_cycles_prev);
static cpumask_var_t amu_fie_cpus;
/* Initialize counter reference per-cpu variables for the current CPU */
void init_cpu_freq_invariance_counters(void)
{
this_cpu_write(arch_core_cycles_prev,
read_sysreg_s(SYS_AMEVCNTR0_CORE_EL0));
this_cpu_write(arch_const_cycles_prev,
read_sysreg_s(SYS_AMEVCNTR0_CONST_EL0));
}
static int validate_cpu_freq_invariance_counters(int cpu)
{
u64 max_freq_hz, ratio;
if (!cpu_has_amu_feat(cpu)) {
pr_debug("CPU%d: counters are not supported.\n", cpu);
return -EINVAL;
}
if (unlikely(!per_cpu(arch_const_cycles_prev, cpu) ||
!per_cpu(arch_core_cycles_prev, cpu))) {
pr_debug("CPU%d: cycle counters are not enabled.\n", cpu);
return -EINVAL;
}
/* Convert maximum frequency from KHz to Hz and validate */
max_freq_hz = cpufreq_get_hw_max_freq(cpu) * 1000;
if (unlikely(!max_freq_hz)) {
pr_debug("CPU%d: invalid maximum frequency.\n", cpu);
return -EINVAL;
}
/*
* Pre-compute the fixed ratio between the frequency of the constant
* counter and the maximum frequency of the CPU.
*
* const_freq
* arch_max_freq_scale = ---------------- * SCHED_CAPACITY_SCALE²
* cpuinfo_max_freq
*
* We use a factor of 2 * SCHED_CAPACITY_SHIFT -> SCHED_CAPACITY_SCALE²
* in order to ensure a good resolution for arch_max_freq_scale for
* very low arch timer frequencies (down to the KHz range which should
* be unlikely).
*/
ratio = (u64)arch_timer_get_rate() << (2 * SCHED_CAPACITY_SHIFT);
ratio = div64_u64(ratio, max_freq_hz);
if (!ratio) {
WARN_ONCE(1, "System timer frequency too low.\n");
return -EINVAL;
}
per_cpu(arch_max_freq_scale, cpu) = (unsigned long)ratio;
return 0;
}
static inline bool
enable_policy_freq_counters(int cpu, cpumask_var_t valid_cpus)
{
struct cpufreq_policy *policy = cpufreq_cpu_get(cpu);
if (!policy) {
pr_debug("CPU%d: No cpufreq policy found.\n", cpu);
return false;
}
if (cpumask_subset(policy->related_cpus, valid_cpus))
cpumask_or(amu_fie_cpus, policy->related_cpus,
amu_fie_cpus);
cpufreq_cpu_put(policy);
return true;
}
static DEFINE_STATIC_KEY_FALSE(amu_fie_key);
#define amu_freq_invariant() static_branch_unlikely(&amu_fie_key)
static int __init init_amu_fie(void)
{
cpumask_var_t valid_cpus;
bool have_policy = false;
int ret = 0;
int cpu;
if (!zalloc_cpumask_var(&valid_cpus, GFP_KERNEL))
return -ENOMEM;
if (!zalloc_cpumask_var(&amu_fie_cpus, GFP_KERNEL)) {
ret = -ENOMEM;
goto free_valid_mask;
}
for_each_present_cpu(cpu) {
if (validate_cpu_freq_invariance_counters(cpu))
continue;
cpumask_set_cpu(cpu, valid_cpus);
have_policy |= enable_policy_freq_counters(cpu, valid_cpus);
}
/*
* If we are not restricted by cpufreq policies, we only enable
* the use of the AMU feature for FIE if all CPUs support AMU.
* Otherwise, enable_policy_freq_counters has already enabled
* policy cpus.
*/
if (!have_policy && cpumask_equal(valid_cpus, cpu_present_mask))
cpumask_or(amu_fie_cpus, amu_fie_cpus, valid_cpus);
if (!cpumask_empty(amu_fie_cpus)) {
pr_info("CPUs[%*pbl]: counters will be used for FIE.",
cpumask_pr_args(amu_fie_cpus));
static_branch_enable(&amu_fie_key);
}
free_valid_mask:
free_cpumask_var(valid_cpus);
return ret;
}
late_initcall_sync(init_amu_fie);
bool arch_freq_counters_available(struct cpumask *cpus)
{
return amu_freq_invariant() &&
cpumask_subset(cpus, amu_fie_cpus);
}
void topology_scale_freq_tick(void)
{
u64 prev_core_cnt, prev_const_cnt;
u64 core_cnt, const_cnt, scale;
int cpu = smp_processor_id();
if (!amu_freq_invariant())
return;
if (!cpumask_test_cpu(cpu, amu_fie_cpus))
return;
const_cnt = read_sysreg_s(SYS_AMEVCNTR0_CONST_EL0);
core_cnt = read_sysreg_s(SYS_AMEVCNTR0_CORE_EL0);
prev_const_cnt = this_cpu_read(arch_const_cycles_prev);
prev_core_cnt = this_cpu_read(arch_core_cycles_prev);
if (unlikely(core_cnt <= prev_core_cnt ||
const_cnt <= prev_const_cnt))
goto store_and_exit;
/*
* /\core arch_max_freq_scale
* scale = ------- * --------------------
* /\const SCHED_CAPACITY_SCALE
*
* See validate_cpu_freq_invariance_counters() for details on
* arch_max_freq_scale and the use of SCHED_CAPACITY_SHIFT.
*/
scale = core_cnt - prev_core_cnt;
scale *= this_cpu_read(arch_max_freq_scale);
scale = div64_u64(scale >> SCHED_CAPACITY_SHIFT,
const_cnt - prev_const_cnt);
scale = min_t(unsigned long, scale, SCHED_CAPACITY_SCALE);
this_cpu_write(freq_scale, (unsigned long)scale);
store_and_exit:
this_cpu_write(arch_core_cycles_prev, core_cnt);
this_cpu_write(arch_const_cycles_prev, const_cnt);
}
#endif /* CONFIG_ARM64_AMU_EXTN */
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