drivers/base/arch_topology.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Arch specific cpu topology information
   4  *
   5  * Copyright (C) 2016, ARM Ltd.
   6  * Written by: Juri Lelli, ARM Ltd.
   7  */
   8
   9 #include <linux/acpi.h>
  10 #include <linux/cpu.h>
  11 #include <linux/cpufreq.h>
  12 #include <linux/device.h>
  13 #include <linux/of.h>
  14 #include <linux/slab.h>
  15 #include <linux/string.h>
  16 #include <linux/sched/topology.h>
  17 #include <linux/cpuset.h>
  18
  19 DEFINE_PER_CPU(unsigned long, freq_scale) = SCHED_CAPACITY_SCALE;
  20
  21 void arch_set_freq_scale(struct cpumask *cpus, unsigned long cur_freq,
  22                          unsigned long max_freq)
  23 {
  24         unsigned long scale;
  25         int i;
  26
  27         scale = (cur_freq << SCHED_CAPACITY_SHIFT) / max_freq;
  28
  29         for_each_cpu(i, cpus)
  30                 per_cpu(freq_scale, i) = scale;
  31 }
  32
  33 DEFINE_PER_CPU(unsigned long, cpu_scale) = SCHED_CAPACITY_SCALE;
  34
  35 void topology_set_cpu_scale(unsigned int cpu, unsigned long capacity)
  36 {
  37         per_cpu(cpu_scale, cpu) = capacity;
  38 }
  39
  40 static ssize_t cpu_capacity_show(struct device *dev,
  41                                  struct device_attribute *attr,
  42                                  char *buf)
  43 {
  44         struct cpu *cpu = container_of(dev, struct cpu, dev);
  45
  46         return sprintf(buf, "%lu\n", topology_get_cpu_scale(cpu->dev.id));
  47 }
  48
  49 static void update_topology_flags_workfn(struct work_struct *work);
  50 static DECLARE_WORK(update_topology_flags_work, update_topology_flags_workfn);
  51
  52 static DEVICE_ATTR_RO(cpu_capacity);
  53
  54 static int register_cpu_capacity_sysctl(void)
  55 {
  56         int i;
  57         struct device *cpu;
  58
  59         for_each_possible_cpu(i) {
  60                 cpu = get_cpu_device(i);
  61                 if (!cpu) {
  62                         pr_err("%s: too early to get CPU%d device!\n",
  63                                __func__, i);
  64                         continue;
  65                 }
  66                 device_create_file(cpu, &dev_attr_cpu_capacity);
  67         }
  68
  69         return 0;
  70 }
  71 subsys_initcall(register_cpu_capacity_sysctl);
  72
  73 static int update_topology;
  74
  75 int topology_update_cpu_topology(void)
  76 {
  77         return update_topology;
  78 }
  79
  80 /*
  81  * Updating the sched_domains can't be done directly from cpufreq callbacks
  82  * due to locking, so queue the work for later.
  83  */
  84 static void update_topology_flags_workfn(struct work_struct *work)
  85 {
  86         update_topology = 1;
  87         rebuild_sched_domains();
  88         pr_debug("sched_domain hierarchy rebuilt, flags updated\n");
  89         update_topology = 0;
  90 }
  91
  92 static u32 capacity_scale;
  93 static u32 *raw_capacity;
  94
  95 static int free_raw_capacity(void)
  96 {
  97         kfree(raw_capacity);
  98         raw_capacity = NULL;
  99
 100         return 0;
 101 }
 102
 103 void topology_normalize_cpu_scale(void)
 104 {
 105         u64 capacity;
 106         int cpu;
 107
 108         if (!raw_capacity)
 109                 return;
 110
 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)
 116                         / capacity_scale;
 117                 topology_set_cpu_scale(cpu, capacity);
 118                 pr_debug("cpu_capacity: CPU%d cpu_capacity=%lu\n",
 119                         cpu, topology_get_cpu_scale(cpu));
 120         }
 121 }
 122
 123 bool __init topology_parse_cpu_capacity(struct device_node *cpu_node, int cpu)
 124 {
 125         static bool cap_parsing_failed;
 126         int ret;
 127         u32 cpu_capacity;
 128
 129         if (cap_parsing_failed)
 130                 return false;
 131
 132         ret = of_property_read_u32(cpu_node, "capacity-dmips-mhz",
 133                                    &cpu_capacity);
 134         if (!ret) {
 135                 if (!raw_capacity) {
 136                         raw_capacity = kcalloc(num_possible_cpus(),
 137                                                sizeof(*raw_capacity),
 138                                                GFP_KERNEL);
 139                         if (!raw_capacity) {
 140                                 cap_parsing_failed = true;
 141                                 return false;
 142                         }
 143                 }
 144                 capacity_scale = max(cpu_capacity, capacity_scale);
 145                 raw_capacity[cpu] = cpu_capacity;
 146                 pr_debug("cpu_capacity: %pOF cpu_capacity=%u (raw)\n",
 147                         cpu_node, raw_capacity[cpu]);
 148         } else {
 149                 if (raw_capacity) {
 150                         pr_err("cpu_capacity: missing %pOF raw capacity\n",
 151                                 cpu_node);
 152                         pr_err("cpu_capacity: partial information: fallback to 1024 for all CPUs\n");
 153                 }
 154                 cap_parsing_failed = true;
 155                 free_raw_capacity();
 156         }
 157
 158         return !ret;
 159 }
 160
 161 #ifdef CONFIG_CPU_FREQ
 162 static cpumask_var_t cpus_to_visit;
 163 static void parsing_done_workfn(struct work_struct *work);
 164 static DECLARE_WORK(parsing_done_work, parsing_done_workfn);
 165
 166 static int
 167 init_cpu_capacity_callback(struct notifier_block *nb,
 168                            unsigned long val,
 169                            void *data)
 170 {
 171         struct cpufreq_policy *policy = data;
 172         int cpu;
 173
 174         if (!raw_capacity)
 175                 return 0;
 176
 177         if (val != CPUFREQ_NOTIFY)
 178                 return 0;
 179
 180         pr_debug("cpu_capacity: init cpu capacity for CPUs [%*pbl] (to_visit=%*pbl)\n",
 181                  cpumask_pr_args(policy->related_cpus),
 182                  cpumask_pr_args(cpus_to_visit));
 183
 184         cpumask_andnot(cpus_to_visit, cpus_to_visit, policy->related_cpus);
 185
 186         for_each_cpu(cpu, policy->related_cpus) {
 187                 raw_capacity[cpu] = topology_get_cpu_scale(cpu) *
 188                                     policy->cpuinfo.max_freq / 1000UL;
 189                 capacity_scale = max(raw_capacity[cpu], capacity_scale);
 190         }
 191
 192         if (cpumask_empty(cpus_to_visit)) {
 193                 topology_normalize_cpu_scale();
 194                 schedule_work(&update_topology_flags_work);
 195                 free_raw_capacity();
 196                 pr_debug("cpu_capacity: parsing done\n");
 197                 schedule_work(&parsing_done_work);
 198         }
 199
 200         return 0;
 201 }
 202
 203 static struct notifier_block init_cpu_capacity_notifier = {
 204         .notifier_call = init_cpu_capacity_callback,
 205 };
 206
 207 static int __init register_cpufreq_notifier(void)
 208 {
 209         int ret;
 210
 211         /*
 212          * on ACPI-based systems we need to use the default cpu capacity
 213          * until we have the necessary code to parse the cpu capacity, so
 214          * skip registering cpufreq notifier.
 215          */
 216         if (!acpi_disabled || !raw_capacity)
 217                 return -EINVAL;
 218
 219         if (!alloc_cpumask_var(&cpus_to_visit, GFP_KERNEL))
 220                 return -ENOMEM;
 221
 222         cpumask_copy(cpus_to_visit, cpu_possible_mask);
 223
 224         ret = cpufreq_register_notifier(&init_cpu_capacity_notifier,
 225                                         CPUFREQ_POLICY_NOTIFIER);
 226
 227         if (ret)
 228                 free_cpumask_var(cpus_to_visit);
 229
 230         return ret;
 231 }
 232 core_initcall(register_cpufreq_notifier);
 233
 234 static void parsing_done_workfn(struct work_struct *work)
 235 {
 236         cpufreq_unregister_notifier(&init_cpu_capacity_notifier,
 237                                          CPUFREQ_POLICY_NOTIFIER);
 238         free_cpumask_var(cpus_to_visit);
 239 }
 240
 241 #else
 242 core_initcall(free_raw_capacity);
 243 #endif