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Diffstat (limited to 'arch/arm64/kernel/topology.c')
| -rw-r--r-- | arch/arm64/kernel/topology.c | 407 |
1 files changed, 407 insertions, 0 deletions
diff --git a/arch/arm64/kernel/topology.c b/arch/arm64/kernel/topology.c new file mode 100644 index 000000000000..5d24dc53799b --- /dev/null +++ b/arch/arm64/kernel/topology.c @@ -0,0 +1,407 @@ +/* + * 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/cpu_smt.h> +#include <linux/init.h> +#include <linux/percpu.h> +#include <linux/sched/isolation.h> +#include <linux/xarray.h> + +#include <asm/cpu.h> +#include <asm/cputype.h> +#include <asm/topology.h> + +#ifdef CONFIG_ARM64_AMU_EXTN +#define read_corecnt() read_sysreg_s(SYS_AMEVCNTR0_CORE_EL0) +#define read_constcnt() read_sysreg_s(SYS_AMEVCNTR0_CONST_EL0) +#else +#define read_corecnt() (0UL) +#define read_constcnt() (0UL) +#endif + +#undef pr_fmt +#define pr_fmt(fmt) "AMU: " fmt + +/* + * Ensure that amu_scale_freq_tick() will return SCHED_CAPACITY_SCALE until + * the CPU capacity and its associated frequency have been correctly + * initialized. + */ +static DEFINE_PER_CPU_READ_MOSTLY(unsigned long, arch_max_freq_scale) = 1UL << (2 * SCHED_CAPACITY_SHIFT); +static cpumask_var_t amu_fie_cpus; + +struct amu_cntr_sample { + u64 arch_const_cycles_prev; + u64 arch_core_cycles_prev; + unsigned long last_scale_update; +}; + +static DEFINE_PER_CPU_SHARED_ALIGNED(struct amu_cntr_sample, cpu_amu_samples); + +void update_freq_counters_refs(void) +{ + struct amu_cntr_sample *amu_sample = this_cpu_ptr(&cpu_amu_samples); + + amu_sample->arch_core_cycles_prev = read_corecnt(); + amu_sample->arch_const_cycles_prev = read_constcnt(); +} + +static inline bool freq_counters_valid(int cpu) +{ + struct amu_cntr_sample *amu_sample = per_cpu_ptr(&cpu_amu_samples, cpu); + + if ((cpu >= nr_cpu_ids) || !cpumask_test_cpu(cpu, cpu_present_mask)) + return false; + + if (!cpu_has_amu_feat(cpu)) { + pr_debug("CPU%d: counters are not supported.\n", cpu); + return false; + } + + if (unlikely(!amu_sample->arch_const_cycles_prev || + !amu_sample->arch_core_cycles_prev)) { + pr_debug("CPU%d: cycle counters are not enabled.\n", cpu); + return false; + } + + return true; +} + +void freq_inv_set_max_ratio(int cpu, u64 max_rate) +{ + u64 ratio, ref_rate = arch_timer_get_rate(); + + if (unlikely(!max_rate || !ref_rate)) { + WARN_ONCE(1, "CPU%d: invalid maximum or reference frequency.\n", + cpu); + return; + } + + /* + * Pre-compute the fixed ratio between the frequency of the constant + * reference counter and the maximum frequency of the CPU. + * + * ref_rate + * arch_max_freq_scale = ---------- * SCHED_CAPACITY_SCALE² + * max_rate + * + * 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 reference frequencies (down to the KHz range which should + * be unlikely). + */ + ratio = ref_rate << (2 * SCHED_CAPACITY_SHIFT); + ratio = div64_u64(ratio, max_rate); + if (!ratio) { + WARN_ONCE(1, "Reference frequency too low.\n"); + return; + } + + WRITE_ONCE(per_cpu(arch_max_freq_scale, cpu), (unsigned long)ratio); +} + +static void amu_scale_freq_tick(void) +{ + struct amu_cntr_sample *amu_sample = this_cpu_ptr(&cpu_amu_samples); + u64 prev_core_cnt, prev_const_cnt; + u64 core_cnt, const_cnt, scale; + + prev_const_cnt = amu_sample->arch_const_cycles_prev; + prev_core_cnt = amu_sample->arch_core_cycles_prev; + + update_freq_counters_refs(); + + const_cnt = amu_sample->arch_const_cycles_prev; + core_cnt = amu_sample->arch_core_cycles_prev; + + /* + * This should not happen unless the AMUs have been reset and the + * counter values have not been restored - unlikely + */ + if (unlikely(core_cnt <= prev_core_cnt || + const_cnt <= prev_const_cnt)) + return; + + /* + * /\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(arch_freq_scale, (unsigned long)scale); + + amu_sample->last_scale_update = jiffies; +} + +static struct scale_freq_data amu_sfd = { + .source = SCALE_FREQ_SOURCE_ARCH, + .set_freq_scale = amu_scale_freq_tick, +}; + +static __always_inline bool amu_fie_cpu_supported(unsigned int cpu) +{ + return cpumask_available(amu_fie_cpus) && + cpumask_test_cpu(cpu, amu_fie_cpus); +} + +void arch_cpu_idle_enter(void) +{ + unsigned int cpu = smp_processor_id(); + + if (!amu_fie_cpu_supported(cpu)) + return; + + /* Kick in AMU update but only if one has not happened already */ + if (housekeeping_cpu(cpu, HK_TYPE_TICK) && + time_is_before_jiffies(per_cpu(cpu_amu_samples.last_scale_update, cpu))) + amu_scale_freq_tick(); +} + +#define AMU_SAMPLE_EXP_MS 20 + +int arch_freq_get_on_cpu(int cpu) +{ + struct amu_cntr_sample *amu_sample; + unsigned int start_cpu = cpu; + unsigned long last_update; + unsigned int freq = 0; + u64 scale; + + if (!amu_fie_cpu_supported(cpu) || !arch_scale_freq_ref(cpu)) + return -EOPNOTSUPP; + + while (1) { + + amu_sample = per_cpu_ptr(&cpu_amu_samples, cpu); + + last_update = amu_sample->last_scale_update; + + /* + * For those CPUs that are in full dynticks mode, or those that have + * not seen tick for a while, try an alternative source for the counters + * (and thus freq scale), if available, for given policy: this boils + * down to identifying an active cpu within the same freq domain, if any. + */ + if (!housekeeping_cpu(cpu, HK_TYPE_TICK) || + time_is_before_jiffies(last_update + msecs_to_jiffies(AMU_SAMPLE_EXP_MS))) { + struct cpufreq_policy *policy = cpufreq_cpu_get(cpu); + int ref_cpu; + + if (!policy) + return -EINVAL; + + if (!cpumask_intersects(policy->related_cpus, + housekeeping_cpumask(HK_TYPE_TICK))) { + cpufreq_cpu_put(policy); + return -EOPNOTSUPP; + } + + for_each_cpu_wrap(ref_cpu, policy->cpus, cpu + 1) { + if (ref_cpu == start_cpu) { + /* Prevent verifying same CPU twice */ + ref_cpu = nr_cpu_ids; + break; + } + if (!idle_cpu(ref_cpu)) + break; + } + + cpufreq_cpu_put(policy); + + if (ref_cpu >= nr_cpu_ids) + /* No alternative to pull info from */ + return -EAGAIN; + + cpu = ref_cpu; + } else { + break; + } + } + /* + * Reversed computation to the one used to determine + * the arch_freq_scale value + * (see amu_scale_freq_tick for details) + */ + scale = arch_scale_freq_capacity(cpu); + freq = scale * arch_scale_freq_ref(cpu); + freq >>= SCHED_CAPACITY_SHIFT; + return freq; +} + +static void amu_fie_setup(const struct cpumask *cpus) +{ + int cpu; + + /* We are already set since the last insmod of cpufreq driver */ + if (cpumask_available(amu_fie_cpus) && + unlikely(cpumask_subset(cpus, amu_fie_cpus))) + return; + + for_each_cpu(cpu, cpus) + if (!freq_counters_valid(cpu)) + return; + + if (!cpumask_available(amu_fie_cpus) && + !zalloc_cpumask_var(&amu_fie_cpus, GFP_KERNEL)) { + WARN_ONCE(1, "Failed to allocate FIE cpumask for CPUs[%*pbl]\n", + cpumask_pr_args(cpus)); + return; + } + + cpumask_or(amu_fie_cpus, amu_fie_cpus, cpus); + + topology_set_scale_freq_source(&amu_sfd, amu_fie_cpus); + + pr_debug("CPUs[%*pbl]: counters will be used for FIE.", + cpumask_pr_args(cpus)); +} + +static int init_amu_fie_callback(struct notifier_block *nb, unsigned long val, + void *data) +{ + struct cpufreq_policy *policy = data; + + if (val == CPUFREQ_CREATE_POLICY) + amu_fie_setup(policy->related_cpus); + + /* + * We don't need to handle CPUFREQ_REMOVE_POLICY event as the AMU + * counters don't have any dependency on cpufreq driver once we have + * initialized AMU support and enabled invariance. The AMU counters will + * keep on working just fine in the absence of the cpufreq driver, and + * for the CPUs for which there are no counters available, the last set + * value of arch_freq_scale will remain valid as that is the frequency + * those CPUs are running at. + */ + + return 0; +} + +static struct notifier_block init_amu_fie_notifier = { + .notifier_call = init_amu_fie_callback, +}; + +static int __init init_amu_fie(void) +{ + return cpufreq_register_notifier(&init_amu_fie_notifier, + CPUFREQ_POLICY_NOTIFIER); +} +core_initcall(init_amu_fie); + +#ifdef CONFIG_ACPI_CPPC_LIB +#include <acpi/cppc_acpi.h> + +static void cpu_read_corecnt(void *val) +{ + /* + * A value of 0 can be returned if the current CPU does not support AMUs + * or if the counter is disabled for this CPU. A return value of 0 at + * counter read is properly handled as an error case by the users of the + * counter. + */ + *(u64 *)val = read_corecnt(); +} + +static void cpu_read_constcnt(void *val) +{ + /* + * Return 0 if the current CPU is affected by erratum 2457168. A value + * of 0 is also returned if the current CPU does not support AMUs or if + * the counter is disabled. A return value of 0 at counter read is + * properly handled as an error case by the users of the counter. + */ + *(u64 *)val = this_cpu_has_cap(ARM64_WORKAROUND_2457168) ? + 0UL : read_constcnt(); +} + +static inline +int counters_read_on_cpu(int cpu, smp_call_func_t func, u64 *val) +{ + /* + * Abort call on counterless CPU or when interrupts are + * disabled - can lead to deadlock in smp sync call. + */ + if (!cpu_has_amu_feat(cpu)) + return -EOPNOTSUPP; + + if (WARN_ON_ONCE(irqs_disabled())) + return -EPERM; + + smp_call_function_single(cpu, func, val, 1); + + return 0; +} + +/* + * Refer to drivers/acpi/cppc_acpi.c for the description of the functions + * below. + */ +bool cpc_ffh_supported(void) +{ + int cpu = get_cpu_with_amu_feat(); + + /* + * FFH is considered supported if there is at least one present CPU that + * supports AMUs. Using FFH to read core and reference counters for CPUs + * that do not support AMUs, have counters disabled or that are affected + * by errata, will result in a return value of 0. + * + * This is done to allow any enabled and valid counters to be read + * through FFH, knowing that potentially returning 0 as counter value is + * properly handled by the users of these counters. + */ + if ((cpu >= nr_cpu_ids) || !cpumask_test_cpu(cpu, cpu_present_mask)) + return false; + + return true; +} + +int cpc_read_ffh(int cpu, struct cpc_reg *reg, u64 *val) +{ + int ret = -EOPNOTSUPP; + + switch ((u64)reg->address) { + case 0x0: + ret = counters_read_on_cpu(cpu, cpu_read_corecnt, val); + break; + case 0x1: + ret = counters_read_on_cpu(cpu, cpu_read_constcnt, val); + break; + } + + if (!ret) { + *val &= GENMASK_ULL(reg->bit_offset + reg->bit_width - 1, + reg->bit_offset); + *val >>= reg->bit_offset; + } + + return ret; +} + +int cpc_write_ffh(int cpunum, struct cpc_reg *reg, u64 val) +{ + return -EOPNOTSUPP; +} +#endif /* CONFIG_ACPI_CPPC_LIB */ |