drivers/base/arch_topology.c

   1 /*
   2  * Arch specific cpu topology information
   3  *
   4  * Copyright (C) 2016, ARM Ltd.
   5  * Written by: Juri Lelli, ARM Ltd.
   6  *
   7  * This file is subject to the terms and conditions of the GNU General Public
   8  * License.  See the file "COPYING" in the main directory of this archive
   9  * for more details.
  10  *
  11  * Released under the GPLv2 only.
  12  * SPDX-License-Identifier: GPL-2.0
  13  */
  14
  15 #include <linux/acpi.h>
  16 #include <linux/cpu.h>
  17 #include <linux/cpufreq.h>
  18 #include <linux/device.h>
  19 #include <linux/of.h>
  20 #include <linux/slab.h>
  21 #include <linux/string.h>
  22 #include <linux/sched/topology.h>
  23
  24 static DEFINE_MUTEX(cpu_scale_mutex);
  25 static DEFINE_PER_CPU(unsigned long, cpu_scale) = SCHED_CAPACITY_SCALE;
  26
  27 unsigned long arch_scale_cpu_capacity(struct sched_domain *sd, int cpu)
  28 {
  29         return per_cpu(cpu_scale, cpu);
  30 }
  31
  32 void set_capacity_scale(unsigned int cpu, unsigned long capacity)
  33 {
  34         per_cpu(cpu_scale, cpu) = capacity;
  35 }
  36
  37 static ssize_t cpu_capacity_show(struct device *dev,
  38                                  struct device_attribute *attr,
  39                                  char *buf)
  40 {
  41         struct cpu *cpu = container_of(dev, struct cpu, dev);
  42
  43         return sprintf(buf, "%lu\n",
  44                         arch_scale_cpu_capacity(NULL, cpu->dev.id));
  45 }
  46
  47 static ssize_t cpu_capacity_store(struct device *dev,
  48                                   struct device_attribute *attr,
  49                                   const char *buf,
  50                                   size_t count)
  51 {
  52         struct cpu *cpu = container_of(dev, struct cpu, dev);
  53         int this_cpu = cpu->dev.id;
  54         int i;
  55         unsigned long new_capacity;
  56         ssize_t ret;
  57
  58         if (!count)
  59                 return 0;
  60
  61         ret = kstrtoul(buf, 0, &new_capacity);
  62         if (ret)
  63                 return ret;
  64         if (new_capacity > SCHED_CAPACITY_SCALE)
  65                 return -EINVAL;
  66
  67         mutex_lock(&cpu_scale_mutex);
  68         for_each_cpu(i, &cpu_topology[this_cpu].core_sibling)
  69                 set_capacity_scale(i, new_capacity);
  70         mutex_unlock(&cpu_scale_mutex);
  71
  72         return count;
  73 }
  74
  75 static DEVICE_ATTR_RW(cpu_capacity);
  76
  77 static int register_cpu_capacity_sysctl(void)
  78 {
  79         int i;
  80         struct device *cpu;
  81
  82         for_each_possible_cpu(i) {
  83                 cpu = get_cpu_device(i);
  84                 if (!cpu) {
  85                         pr_err("%s: too early to get CPU%d device!\n",
  86                                __func__, i);
  87                         continue;
  88                 }
  89                 device_create_file(cpu, &dev_attr_cpu_capacity);
  90         }
  91
  92         return 0;
  93 }
  94 subsys_initcall(register_cpu_capacity_sysctl);
  95
  96 static u32 capacity_scale;
  97 static u32 *raw_capacity;
  98 static bool cap_parsing_failed;
  99
 100 void normalize_cpu_capacity(void)
 101 {
 102         u64 capacity;
 103         int cpu;
 104
 105         if (!raw_capacity || cap_parsing_failed)
 106                 return;
 107
 108         pr_debug("cpu_capacity: capacity_scale=%u\n", capacity_scale);
 109         mutex_lock(&cpu_scale_mutex);
 110         for_each_possible_cpu(cpu) {
 111                 pr_debug("cpu_capacity: cpu=%d raw_capacity=%u\n",
 112                          cpu, raw_capacity[cpu]);
 113                 capacity = (raw_capacity[cpu] << SCHED_CAPACITY_SHIFT)
 114                         / capacity_scale;
 115                 set_capacity_scale(cpu, capacity);
 116                 pr_debug("cpu_capacity: CPU%d cpu_capacity=%lu\n",
 117                         cpu, arch_scale_cpu_capacity(NULL, cpu));
 118         }
 119         mutex_unlock(&cpu_scale_mutex);
 120 }
 121
 122 int __init parse_cpu_capacity(struct device_node *cpu_node, int cpu)
 123 {
 124         int ret = 1;
 125         u32 cpu_capacity;
 126
 127         if (cap_parsing_failed)
 128                 return !ret;
 129
 130         ret = of_property_read_u32(cpu_node,
 131                                    "capacity-dmips-mhz",
 132                                    &cpu_capacity);
 133         if (!ret) {
 134                 if (!raw_capacity) {
 135                         raw_capacity = kcalloc(num_possible_cpus(),
 136                                                sizeof(*raw_capacity),
 137                                                GFP_KERNEL);
 138                         if (!raw_capacity) {
 139                                 pr_err("cpu_capacity: failed to allocate memory for raw capacities\n");
 140                                 cap_parsing_failed = true;
 141                                 return 0;
 142                         }
 143                 }
 144                 capacity_scale = max(cpu_capacity, capacity_scale);
 145                 raw_capacity[cpu] = cpu_capacity;
 146                 pr_debug("cpu_capacity: %s cpu_capacity=%u (raw)\n",
 147                         cpu_node->full_name, raw_capacity[cpu]);
 148         } else {
 149                 if (raw_capacity) {
 150                         pr_err("cpu_capacity: missing %s raw capacity\n",
 151                                 cpu_node->full_name);
 152                         pr_err("cpu_capacity: partial information: fallback to 1024 for all CPUs\n");
 153                 }
 154                 cap_parsing_failed = true;
 155                 kfree(raw_capacity);
 156         }
 157
 158         return !ret;
 159 }
 160
 161 #ifdef CONFIG_CPU_FREQ
 162 static cpumask_var_t cpus_to_visit;
 163 static bool cap_parsing_done;
 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 (cap_parsing_failed || cap_parsing_done)
 176                 return 0;
 177
 178         switch (val) {
 179         case CPUFREQ_NOTIFY:
 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                 cpumask_andnot(cpus_to_visit,
 184                                cpus_to_visit,
 185                                policy->related_cpus);
 186                 for_each_cpu(cpu, policy->related_cpus) {
 187                         raw_capacity[cpu] = arch_scale_cpu_capacity(NULL, cpu) *
 188                                             policy->cpuinfo.max_freq / 1000UL;
 189                         capacity_scale = max(raw_capacity[cpu], capacity_scale);
 190                 }
 191                 if (cpumask_empty(cpus_to_visit)) {
 192                         normalize_cpu_capacity();
 193                         kfree(raw_capacity);
 194                         pr_debug("cpu_capacity: parsing done\n");
 195                         cap_parsing_done = true;
 196                         schedule_work(&parsing_done_work);
 197                 }
 198         }
 199         return 0;
 200 }
 201
 202 static struct notifier_block init_cpu_capacity_notifier = {
 203         .notifier_call = init_cpu_capacity_callback,
 204 };
 205
 206 static int __init register_cpufreq_notifier(void)
 207 {
 208         /*
 209          * on ACPI-based systems we need to use the default cpu capacity
 210          * until we have the necessary code to parse the cpu capacity, so
 211          * skip registering cpufreq notifier.
 212          */
 213         if (!acpi_disabled || !raw_capacity)
 214                 return -EINVAL;
 215
 216         if (!alloc_cpumask_var(&cpus_to_visit, GFP_KERNEL)) {
 217                 pr_err("cpu_capacity: failed to allocate memory for cpus_to_visit\n");
 218                 return -ENOMEM;
 219         }
 220
 221         cpumask_copy(cpus_to_visit, cpu_possible_mask);
 222
 223         return cpufreq_register_notifier(&init_cpu_capacity_notifier,
 224                                          CPUFREQ_POLICY_NOTIFIER);
 225 }
 226 core_initcall(register_cpufreq_notifier);
 227
 228 static void parsing_done_workfn(struct work_struct *work)
 229 {
 230         cpufreq_unregister_notifier(&init_cpu_capacity_notifier,
 231                                          CPUFREQ_POLICY_NOTIFIER);
 232 }
 233
 234 #else
 235 static int __init free_raw_capacity(void)
 236 {
 237         kfree(raw_capacity);
 238
 239         return 0;
 240 }
 241 core_initcall(free_raw_capacity);
 242 #endif