diff options
Diffstat (limited to 'drivers/base/arch_topology.c')
| -rw-r--r-- | drivers/base/arch_topology.c | 243 |
1 files changed, 243 insertions, 0 deletions
diff --git a/drivers/base/arch_topology.c b/drivers/base/arch_topology.c new file mode 100644 index 000000000000..d1c33a85059e --- /dev/null +++ b/drivers/base/arch_topology.c @@ -0,0 +1,243 @@ +/* + * Arch specific cpu topology information + * + * Copyright (C) 2016, ARM Ltd. + * Written by: Juri Lelli, ARM Ltd. + * + * 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. + * + * Released under the GPLv2 only. + * SPDX-License-Identifier: GPL-2.0 + */ + +#include <linux/acpi.h> +#include <linux/arch_topology.h> +#include <linux/cpu.h> +#include <linux/cpufreq.h> +#include <linux/device.h> +#include <linux/of.h> +#include <linux/slab.h> +#include <linux/string.h> +#include <linux/sched/topology.h> + +static DEFINE_MUTEX(cpu_scale_mutex); +static DEFINE_PER_CPU(unsigned long, cpu_scale) = SCHED_CAPACITY_SCALE; + +unsigned long topology_get_cpu_scale(struct sched_domain *sd, int cpu) +{ + return per_cpu(cpu_scale, cpu); +} + +void topology_set_cpu_scale(unsigned int cpu, unsigned long capacity) +{ + per_cpu(cpu_scale, cpu) = capacity; +} + +static ssize_t cpu_capacity_show(struct device *dev, + struct device_attribute *attr, + char *buf) +{ + struct cpu *cpu = container_of(dev, struct cpu, dev); + + return sprintf(buf, "%lu\n", + topology_get_cpu_scale(NULL, cpu->dev.id)); +} + +static ssize_t cpu_capacity_store(struct device *dev, + struct device_attribute *attr, + const char *buf, + size_t count) +{ + struct cpu *cpu = container_of(dev, struct cpu, dev); + int this_cpu = cpu->dev.id; + int i; + unsigned long new_capacity; + ssize_t ret; + + if (!count) + return 0; + + ret = kstrtoul(buf, 0, &new_capacity); + if (ret) + return ret; + if (new_capacity > SCHED_CAPACITY_SCALE) + return -EINVAL; + + mutex_lock(&cpu_scale_mutex); + for_each_cpu(i, &cpu_topology[this_cpu].core_sibling) + topology_set_cpu_scale(i, new_capacity); + mutex_unlock(&cpu_scale_mutex); + + return count; +} + +static DEVICE_ATTR_RW(cpu_capacity); + +static int register_cpu_capacity_sysctl(void) +{ + int i; + struct device *cpu; + + for_each_possible_cpu(i) { + cpu = get_cpu_device(i); + if (!cpu) { + pr_err("%s: too early to get CPU%d device!\n", + __func__, i); + continue; + } + device_create_file(cpu, &dev_attr_cpu_capacity); + } + + return 0; +} +subsys_initcall(register_cpu_capacity_sysctl); + +static u32 capacity_scale; +static u32 *raw_capacity; +static bool cap_parsing_failed; + +void topology_normalize_cpu_scale(void) +{ + u64 capacity; + int cpu; + + if (!raw_capacity || cap_parsing_failed) + return; + + pr_debug("cpu_capacity: capacity_scale=%u\n", capacity_scale); + mutex_lock(&cpu_scale_mutex); + for_each_possible_cpu(cpu) { + pr_debug("cpu_capacity: cpu=%d raw_capacity=%u\n", + cpu, raw_capacity[cpu]); + capacity = (raw_capacity[cpu] << SCHED_CAPACITY_SHIFT) + / capacity_scale; + topology_set_cpu_scale(cpu, capacity); + pr_debug("cpu_capacity: CPU%d cpu_capacity=%lu\n", + cpu, topology_get_cpu_scale(NULL, cpu)); + } + mutex_unlock(&cpu_scale_mutex); +} + +int __init topology_parse_cpu_capacity(struct device_node *cpu_node, int cpu) +{ + int ret = 1; + u32 cpu_capacity; + + if (cap_parsing_failed) + return !ret; + + ret = of_property_read_u32(cpu_node, + "capacity-dmips-mhz", + &cpu_capacity); + if (!ret) { + if (!raw_capacity) { + raw_capacity = kcalloc(num_possible_cpus(), + sizeof(*raw_capacity), + GFP_KERNEL); + if (!raw_capacity) { + pr_err("cpu_capacity: failed to allocate memory for raw capacities\n"); + cap_parsing_failed = true; + return 0; + } + } + capacity_scale = max(cpu_capacity, capacity_scale); + raw_capacity[cpu] = cpu_capacity; + pr_debug("cpu_capacity: %s cpu_capacity=%u (raw)\n", + cpu_node->full_name, raw_capacity[cpu]); + } else { + if (raw_capacity) { + pr_err("cpu_capacity: missing %s raw capacity\n", + cpu_node->full_name); + pr_err("cpu_capacity: partial information: fallback to 1024 for all CPUs\n"); + } + cap_parsing_failed = true; + kfree(raw_capacity); + } + + return !ret; +} + +#ifdef CONFIG_CPU_FREQ +static cpumask_var_t cpus_to_visit; +static bool cap_parsing_done; +static void parsing_done_workfn(struct work_struct *work); +static DECLARE_WORK(parsing_done_work, parsing_done_workfn); + +static int +init_cpu_capacity_callback(struct notifier_block *nb, + unsigned long val, + void *data) +{ + struct cpufreq_policy *policy = data; + int cpu; + + if (cap_parsing_failed || cap_parsing_done) + return 0; + + switch (val) { + case CPUFREQ_NOTIFY: + pr_debug("cpu_capacity: init cpu capacity for CPUs [%*pbl] (to_visit=%*pbl)\n", + cpumask_pr_args(policy->related_cpus), + cpumask_pr_args(cpus_to_visit)); + cpumask_andnot(cpus_to_visit, + cpus_to_visit, + policy->related_cpus); + for_each_cpu(cpu, policy->related_cpus) { + raw_capacity[cpu] = topology_get_cpu_scale(NULL, cpu) * + policy->cpuinfo.max_freq / 1000UL; + capacity_scale = max(raw_capacity[cpu], capacity_scale); + } + if (cpumask_empty(cpus_to_visit)) { + topology_normalize_cpu_scale(); + kfree(raw_capacity); + pr_debug("cpu_capacity: parsing done\n"); + cap_parsing_done = true; + schedule_work(&parsing_done_work); + } + } + return 0; +} + +static struct notifier_block init_cpu_capacity_notifier = { + .notifier_call = init_cpu_capacity_callback, +}; + +static int __init register_cpufreq_notifier(void) +{ + /* + * on ACPI-based systems we need to use the default cpu capacity + * until we have the necessary code to parse the cpu capacity, so + * skip registering cpufreq notifier. + */ + if (!acpi_disabled || !raw_capacity) + return -EINVAL; + + if (!alloc_cpumask_var(&cpus_to_visit, GFP_KERNEL)) { + pr_err("cpu_capacity: failed to allocate memory for cpus_to_visit\n"); + return -ENOMEM; + } + + cpumask_copy(cpus_to_visit, cpu_possible_mask); + + return cpufreq_register_notifier(&init_cpu_capacity_notifier, + CPUFREQ_POLICY_NOTIFIER); +} +core_initcall(register_cpufreq_notifier); + +static void parsing_done_workfn(struct work_struct *work) +{ + cpufreq_unregister_notifier(&init_cpu_capacity_notifier, + CPUFREQ_POLICY_NOTIFIER); +} + +#else +static int __init free_raw_capacity(void) +{ + kfree(raw_capacity); + + return 0; +} +core_initcall(free_raw_capacity); +#endif |