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/arch_topology.h>
  17 #include <linux/cpu.h>
  18 #include <linux/cpufreq.h>
  19 #include <linux/device.h>
  20 #include <linux/of.h>
  21 #include <linux/slab.h>
  22 #include <linux/string.h>
  23 #include <linux/sched/topology.h>
  24
  25 static DEFINE_MUTEX(cpu_scale_mutex);
  26 static DEFINE_PER_CPU(unsigned long, cpu_scale) = SCHED_CAPACITY_SCALE;
  27
  28 unsigned long topology_get_cpu_scale(struct sched_domain *sd, int cpu)
  29 {
  30         return per_cpu(cpu_scale, cpu);
  31 }
  32
  33 void topology_set_cpu_scale(unsigned int cpu, unsigned long capacity)
  34 {
  35         per_cpu(cpu_scale, cpu) = capacity;
  36 }
  37
  38 static ssize_t cpu_capacity_show(struct device *dev,
  39                                  struct device_attribute *attr,
  40                                  char *buf)
  41 {
  42         struct cpu *cpu = container_of(dev, struct cpu, dev);
  43
  44         return sprintf(buf, "%lu\n",
  45                         topology_get_cpu_scale(NULL, cpu->dev.id));
  46 }
  47
  48 static ssize_t cpu_capacity_store(struct device *dev,
  49                                   struct device_attribute *attr,
  50                                   const char *buf,
  51                                   size_t count)
  52 {
  53         struct cpu *cpu = container_of(dev, struct cpu, dev);
  54         int this_cpu = cpu->dev.id;
  55         int i;
  56         unsigned long new_capacity;
  57         ssize_t ret;
  58
  59         if (!count)
  60                 return 0;
  61
  62         ret = kstrtoul(buf, 0, &new_capacity);
  63         if (ret)
  64                 return ret;
  65         if (new_capacity > SCHED_CAPACITY_SCALE)
  66                 return -EINVAL;
  67
  68         mutex_lock(&cpu_scale_mutex);
  69         for_each_cpu(i, &cpu_topology[this_cpu].core_sibling)
  70                 topology_set_cpu_scale(i, new_capacity);
  71         mutex_unlock(&cpu_scale_mutex);
  72
  73         return count;
  74 }
  75
  76 static DEVICE_ATTR_RW(cpu_capacity);
  77
  78 static int register_cpu_capacity_sysctl(void)
  79 {
  80         int i;
  81         struct device *cpu;
  82
  83         for_each_possible_cpu(i) {
  84                 cpu = get_cpu_device(i);
  85                 if (!cpu) {
  86                         pr_err("%s: too early to get CPU%d device!\n",
  87                                __func__, i);
  88                         continue;
  89                 }
  90                 device_create_file(cpu, &dev_attr_cpu_capacity);
  91         }
  92
  93         return 0;
  94 }
  95 subsys_initcall(register_cpu_capacity_sysctl);
  96
  97 static u32 capacity_scale;
  98 static u32 *raw_capacity;
  99 static bool cap_parsing_failed;
 100
 101 void topology_normalize_cpu_scale(void)
 102 {
 103         u64 capacity;
 104         int cpu;
 105
 106         if (!raw_capacity || cap_parsing_failed)
 107                 return;
 108
 109         pr_debug("cpu_capacity: capacity_scale=%u\n", capacity_scale);
 110         mutex_lock(&cpu_scale_mutex);
 111         for_each_possible_cpu(cpu) {
 112                 pr_debug("cpu_capacity: cpu=%d raw_capacity=%u\n",
 113                          cpu, raw_capacity[cpu]);
 114                 capacity = (raw_capacity[cpu] << SCHED_CAPACITY_SHIFT)
 115                         / capacity_scale;
 116                 topology_set_cpu_scale(cpu, capacity);
 117                 pr_debug("cpu_capacity: CPU%d cpu_capacity=%lu\n",
 118                         cpu, topology_get_cpu_scale(NULL, cpu));
 119         }
 120         mutex_unlock(&cpu_scale_mutex);
 121 }
 122
 123 int __init topology_parse_cpu_capacity(struct device_node *cpu_node, int cpu)
 124 {
 125         int ret = 1;
 126         u32 cpu_capacity;
 127
 128         if (cap_parsing_failed)
 129                 return !ret;
 130
 131         ret = of_property_read_u32(cpu_node,
 132                                    "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 0;
 143                         }
 144                 }
 145                 capacity_scale = max(cpu_capacity, capacity_scale);
 146                 raw_capacity[cpu] = cpu_capacity;
 147                 pr_debug("cpu_capacity: %s cpu_capacity=%u (raw)\n",
 148                         cpu_node->full_name, raw_capacity[cpu]);
 149         } else {
 150                 if (raw_capacity) {
 151                         pr_err("cpu_capacity: missing %s raw capacity\n",
 152                                 cpu_node->full_name);
 153                         pr_err("cpu_capacity: partial information: fallback to 1024 for all CPUs\n");
 154                 }
 155                 cap_parsing_failed = true;
 156                 kfree(raw_capacity);
 157         }
 158
 159         return !ret;
 160 }
 161
 162 #ifdef CONFIG_CPU_FREQ
 163 static cpumask_var_t cpus_to_visit;
 164 static bool cap_parsing_done;
 165 static void parsing_done_workfn(struct work_struct *work);
 166 static DECLARE_WORK(parsing_done_work, parsing_done_workfn);
 167
 168 static int
 169 init_cpu_capacity_callback(struct notifier_block *nb,
 170                            unsigned long val,
 171                            void *data)
 172 {
 173         struct cpufreq_policy *policy = data;
 174         int cpu;
 175
 176         if (cap_parsing_failed || cap_parsing_done)
 177                 return 0;
 178
 179         switch (val) {
 180         case 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));
 184                 cpumask_andnot(cpus_to_visit,
 185                                cpus_to_visit,
 186                                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);
 191                 }
 192                 if (cpumask_empty(cpus_to_visit)) {
 193                         topology_normalize_cpu_scale();
 194                         kfree(raw_capacity);
 195                         pr_debug("cpu_capacity: parsing done\n");
 196                         cap_parsing_done = true;
 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         /*
 210          * on ACPI-based systems we need to use the default cpu capacity
 211          * until we have the necessary code to parse the cpu capacity, so
 212          * skip registering cpufreq notifier.
 213          */
 214         if (!acpi_disabled || !raw_capacity)
 215                 return -EINVAL;
 216
 217         if (!alloc_cpumask_var(&cpus_to_visit, GFP_KERNEL)) {
 218                 pr_err("cpu_capacity: failed to allocate memory for cpus_to_visit\n");
 219                 return -ENOMEM;
 220         }
 221
 222         cpumask_copy(cpus_to_visit, cpu_possible_mask);
 223
 224         return cpufreq_register_notifier(&init_cpu_capacity_notifier,
 225                                          CPUFREQ_POLICY_NOTIFIER);
 226 }
 227 core_initcall(register_cpufreq_notifier);
 228
 229 static void parsing_done_workfn(struct work_struct *work)
 230 {
 231         cpufreq_unregister_notifier(&init_cpu_capacity_notifier,
 232                                          CPUFREQ_POLICY_NOTIFIER);
 233 }
 234
 235 #else
 236 static int __init free_raw_capacity(void)
 237 {
 238         kfree(raw_capacity);
 239
 240         return 0;
 241 }
 242 core_initcall(free_raw_capacity);
 243 #endif