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(NULL, 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(NULL, 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                                 pr_err("cpu_capacity: failed to allocate memory for raw capacities\n");
 141                                 cap_parsing_failed = true;
 142                                 return false;
 143                         }
 144                 }
 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]);
 149         } else {
 150                 if (raw_capacity) {
 151                         pr_err("cpu_capacity: missing %pOF raw capacity\n",
 152                                 cpu_node);
 153                         pr_err("cpu_capacity: partial information: fallback to 1024 for all CPUs\n");
 154                 }
 155                 cap_parsing_failed = true;
 156                 free_raw_capacity();
 157         }
 158
 159         return !ret;
 160 }
 161
 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);
 166
 167 static int
 168 init_cpu_capacity_callback(struct notifier_block *nb,
 169                            unsigned long val,
 170                            void *data)
 171 {
 172         struct cpufreq_policy *policy = data;
 173         int cpu;
 174
 175         if (!raw_capacity)
 176                 return 0;
 177
 178         if (val != CPUFREQ_NOTIFY)
 179                 return 0;
 180
 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));
 184
 185         cpumask_andnot(cpus_to_visit, cpus_to_visit, policy->related_cpus);
 186
 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);
 191         }
 192
 193         if (cpumask_empty(cpus_to_visit)) {
 194                 topology_normalize_cpu_scale();
 195                 schedule_work(&update_topology_flags_work);
 196                 free_raw_capacity();
 197                 pr_debug("cpu_capacity: parsing done\n");
 198                 schedule_work(&parsing_done_work);
 199         }
 200
 201         return 0;
 202 }
 203
 204 static struct notifier_block init_cpu_capacity_notifier = {
 205         .notifier_call = init_cpu_capacity_callback,
 206 };
 207
 208 static int __init register_cpufreq_notifier(void)
 209 {
 210         int ret;
 211
 212         /*
 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.
 216          */
 217         if (!acpi_disabled || !raw_capacity)
 218                 return -EINVAL;
 219
 220         if (!alloc_cpumask_var(&cpus_to_visit, GFP_KERNEL)) {
 221                 pr_err("cpu_capacity: failed to allocate memory for cpus_to_visit\n");
 222                 return -ENOMEM;
 223         }
 224
 225         cpumask_copy(cpus_to_visit, cpu_possible_mask);
 226
 227         ret = cpufreq_register_notifier(&init_cpu_capacity_notifier,
 228                                         CPUFREQ_POLICY_NOTIFIER);
 229
 230         if (ret)
 231                 free_cpumask_var(cpus_to_visit);
 232
 233         return ret;
 234 }
 235 core_initcall(register_cpufreq_notifier);
 236
 237 static void parsing_done_workfn(struct work_struct *work)
 238 {
 239         cpufreq_unregister_notifier(&init_cpu_capacity_notifier,
 240                                          CPUFREQ_POLICY_NOTIFIER);
 241         free_cpumask_var(cpus_to_visit);
 242 }
 243
 244 #else
 245 core_initcall(free_raw_capacity);
 246 #endif