1 // SPDX-License-Identifier: GPL-2.0
3 * Arch specific cpu topology information
5 * Copyright (C) 2016, ARM Ltd.
6 * Written by: Juri Lelli, ARM Ltd.
9 #include <linux/acpi.h>
10 #include <linux/cpu.h>
11 #include <linux/cpufreq.h>
12 #include <linux/device.h>
14 #include <linux/slab.h>
15 #include <linux/string.h>
16 #include <linux/sched/topology.h>
17 #include <linux/cpuset.h>
19 DEFINE_PER_CPU(unsigned long, freq_scale) = SCHED_CAPACITY_SCALE;
21 void arch_set_freq_scale(struct cpumask *cpus, unsigned long cur_freq,
22 unsigned long max_freq)
27 scale = (cur_freq << SCHED_CAPACITY_SHIFT) / max_freq;
30 per_cpu(freq_scale, i) = scale;
33 DEFINE_PER_CPU(unsigned long, cpu_scale) = SCHED_CAPACITY_SCALE;
35 void topology_set_cpu_scale(unsigned int cpu, unsigned long capacity)
37 per_cpu(cpu_scale, cpu) = capacity;
40 static ssize_t cpu_capacity_show(struct device *dev,
41 struct device_attribute *attr,
44 struct cpu *cpu = container_of(dev, struct cpu, dev);
46 return sprintf(buf, "%lu\n", topology_get_cpu_scale(NULL, cpu->dev.id));
49 static void update_topology_flags_workfn(struct work_struct *work);
50 static DECLARE_WORK(update_topology_flags_work, update_topology_flags_workfn);
52 static DEVICE_ATTR_RO(cpu_capacity);
54 static int register_cpu_capacity_sysctl(void)
59 for_each_possible_cpu(i) {
60 cpu = get_cpu_device(i);
62 pr_err("%s: too early to get CPU%d device!\n",
66 device_create_file(cpu, &dev_attr_cpu_capacity);
71 subsys_initcall(register_cpu_capacity_sysctl);
73 static int update_topology;
75 int topology_update_cpu_topology(void)
77 return update_topology;
81 * Updating the sched_domains can't be done directly from cpufreq callbacks
82 * due to locking, so queue the work for later.
84 static void update_topology_flags_workfn(struct work_struct *work)
87 rebuild_sched_domains();
88 pr_debug("sched_domain hierarchy rebuilt, flags updated\n");
92 static u32 capacity_scale;
93 static u32 *raw_capacity;
95 static int free_raw_capacity(void)
103 void topology_normalize_cpu_scale(void)
111 pr_debug("cpu_capacity: capacity_scale=%u\n", capacity_scale);
112 for_each_possible_cpu(cpu) {
113 pr_debug("cpu_capacity: cpu=%d raw_capacity=%u\n",
114 cpu, raw_capacity[cpu]);
115 capacity = (raw_capacity[cpu] << SCHED_CAPACITY_SHIFT)
117 topology_set_cpu_scale(cpu, capacity);
118 pr_debug("cpu_capacity: CPU%d cpu_capacity=%lu\n",
119 cpu, topology_get_cpu_scale(NULL, cpu));
123 bool __init topology_parse_cpu_capacity(struct device_node *cpu_node, int cpu)
125 static bool cap_parsing_failed;
129 if (cap_parsing_failed)
132 ret = of_property_read_u32(cpu_node, "capacity-dmips-mhz",
136 raw_capacity = kcalloc(num_possible_cpus(),
137 sizeof(*raw_capacity),
140 pr_err("cpu_capacity: failed to allocate memory for raw capacities\n");
141 cap_parsing_failed = true;
145 capacity_scale = max(cpu_capacity, capacity_scale);
146 raw_capacity[cpu] = cpu_capacity;
147 pr_debug("cpu_capacity: %pOF cpu_capacity=%u (raw)\n",
148 cpu_node, raw_capacity[cpu]);
151 pr_err("cpu_capacity: missing %pOF raw capacity\n",
153 pr_err("cpu_capacity: partial information: fallback to 1024 for all CPUs\n");
155 cap_parsing_failed = true;
162 #ifdef CONFIG_CPU_FREQ
163 static cpumask_var_t cpus_to_visit;
164 static void parsing_done_workfn(struct work_struct *work);
165 static DECLARE_WORK(parsing_done_work, parsing_done_workfn);
168 init_cpu_capacity_callback(struct notifier_block *nb,
172 struct cpufreq_policy *policy = data;
178 if (val != CPUFREQ_NOTIFY)
181 pr_debug("cpu_capacity: init cpu capacity for CPUs [%*pbl] (to_visit=%*pbl)\n",
182 cpumask_pr_args(policy->related_cpus),
183 cpumask_pr_args(cpus_to_visit));
185 cpumask_andnot(cpus_to_visit, cpus_to_visit, policy->related_cpus);
187 for_each_cpu(cpu, policy->related_cpus) {
188 raw_capacity[cpu] = topology_get_cpu_scale(NULL, cpu) *
189 policy->cpuinfo.max_freq / 1000UL;
190 capacity_scale = max(raw_capacity[cpu], capacity_scale);
193 if (cpumask_empty(cpus_to_visit)) {
194 topology_normalize_cpu_scale();
195 schedule_work(&update_topology_flags_work);
197 pr_debug("cpu_capacity: parsing done\n");
198 schedule_work(&parsing_done_work);
204 static struct notifier_block init_cpu_capacity_notifier = {
205 .notifier_call = init_cpu_capacity_callback,
208 static int __init register_cpufreq_notifier(void)
213 * on ACPI-based systems we need to use the default cpu capacity
214 * until we have the necessary code to parse the cpu capacity, so
215 * skip registering cpufreq notifier.
217 if (!acpi_disabled || !raw_capacity)
220 if (!alloc_cpumask_var(&cpus_to_visit, GFP_KERNEL)) {
221 pr_err("cpu_capacity: failed to allocate memory for cpus_to_visit\n");
225 cpumask_copy(cpus_to_visit, cpu_possible_mask);
227 ret = cpufreq_register_notifier(&init_cpu_capacity_notifier,
228 CPUFREQ_POLICY_NOTIFIER);
231 free_cpumask_var(cpus_to_visit);
235 core_initcall(register_cpufreq_notifier);
237 static void parsing_done_workfn(struct work_struct *work)
239 cpufreq_unregister_notifier(&init_cpu_capacity_notifier,
240 CPUFREQ_POLICY_NOTIFIER);
241 free_cpumask_var(cpus_to_visit);
245 core_initcall(free_raw_capacity);