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", topology_get_cpu_scale(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                 topology_set_cpu_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
  99 static int __init free_raw_capacity(void)
 100 {
 101         kfree(raw_capacity);
 102         raw_capacity = NULL;
 103
 104         return 0;
 105 }
 106
 107 void topology_normalize_cpu_scale(void)
 108 {
 109         u64 capacity;
 110         int cpu;
 111
 112         if (!raw_capacity)
 113                 return;
 114
 115         pr_debug("cpu_capacity: capacity_scale=%u\n", capacity_scale);
 116         mutex_lock(&cpu_scale_mutex);
 117         for_each_possible_cpu(cpu) {
 118                 pr_debug("cpu_capacity: cpu=%d raw_capacity=%u\n",
 119                          cpu, raw_capacity[cpu]);
 120                 capacity = (raw_capacity[cpu] << SCHED_CAPACITY_SHIFT)
 121                         / capacity_scale;
 122                 topology_set_cpu_scale(cpu, capacity);
 123                 pr_debug("cpu_capacity: CPU%d cpu_capacity=%lu\n",
 124                         cpu, topology_get_cpu_scale(NULL, cpu));
 125         }
 126         mutex_unlock(&cpu_scale_mutex);
 127 }
 128
 129 bool __init topology_parse_cpu_capacity(struct device_node *cpu_node, int cpu)
 130 {
 131         static bool cap_parsing_failed;
 132         int ret;
 133         u32 cpu_capacity;
 134
 135         if (cap_parsing_failed)
 136                 return false;
 137
 138         ret = of_property_read_u32(cpu_node, "capacity-dmips-mhz",
 139                                    &cpu_capacity);
 140         if (!ret) {
 141                 if (!raw_capacity) {
 142                         raw_capacity = kcalloc(num_possible_cpus(),
 143                                                sizeof(*raw_capacity),
 144                                                GFP_KERNEL);
 145                         if (!raw_capacity) {
 146                                 pr_err("cpu_capacity: failed to allocate memory for raw capacities\n");
 147                                 cap_parsing_failed = true;
 148                                 return false;
 149                         }
 150                 }
 151                 capacity_scale = max(cpu_capacity, capacity_scale);
 152                 raw_capacity[cpu] = cpu_capacity;
 153                 pr_debug("cpu_capacity: %pOF cpu_capacity=%u (raw)\n",
 154                         cpu_node, raw_capacity[cpu]);
 155         } else {
 156                 if (raw_capacity) {
 157                         pr_err("cpu_capacity: missing %pOF raw capacity\n",
 158                                 cpu_node);
 159                         pr_err("cpu_capacity: partial information: fallback to 1024 for all CPUs\n");
 160                 }
 161                 cap_parsing_failed = true;
 162                 free_raw_capacity();
 163         }
 164
 165         return !ret;
 166 }
 167
 168 #ifdef CONFIG_CPU_FREQ
 169 static cpumask_var_t cpus_to_visit __initdata;
 170 static void __init parsing_done_workfn(struct work_struct *work);
 171 static __initdata DECLARE_WORK(parsing_done_work, parsing_done_workfn);
 172
 173 static int __init
 174 init_cpu_capacity_callback(struct notifier_block *nb,
 175                            unsigned long val,
 176                            void *data)
 177 {
 178         struct cpufreq_policy *policy = data;
 179         int cpu;
 180
 181         if (!raw_capacity)
 182                 return 0;
 183
 184         if (val != CPUFREQ_NOTIFY)
 185                 return 0;
 186
 187         pr_debug("cpu_capacity: init cpu capacity for CPUs [%*pbl] (to_visit=%*pbl)\n",
 188                  cpumask_pr_args(policy->related_cpus),
 189                  cpumask_pr_args(cpus_to_visit));
 190
 191         cpumask_andnot(cpus_to_visit, cpus_to_visit, policy->related_cpus);
 192
 193         for_each_cpu(cpu, policy->related_cpus) {
 194                 raw_capacity[cpu] = topology_get_cpu_scale(NULL, cpu) *
 195                                     policy->cpuinfo.max_freq / 1000UL;
 196                 capacity_scale = max(raw_capacity[cpu], capacity_scale);
 197         }
 198
 199         if (cpumask_empty(cpus_to_visit)) {
 200                 topology_normalize_cpu_scale();
 201                 free_raw_capacity();
 202                 pr_debug("cpu_capacity: parsing done\n");
 203                 schedule_work(&parsing_done_work);
 204         }
 205
 206         return 0;
 207 }
 208
 209 static struct notifier_block init_cpu_capacity_notifier __initdata = {
 210         .notifier_call = init_cpu_capacity_callback,
 211 };
 212
 213 static int __init register_cpufreq_notifier(void)
 214 {
 215         /*
 216          * on ACPI-based systems we need to use the default cpu capacity
 217          * until we have the necessary code to parse the cpu capacity, so
 218          * skip registering cpufreq notifier.
 219          */
 220         if (!acpi_disabled || !raw_capacity)
 221                 return -EINVAL;
 222
 223         if (!alloc_cpumask_var(&cpus_to_visit, GFP_KERNEL)) {
 224                 pr_err("cpu_capacity: failed to allocate memory for cpus_to_visit\n");
 225                 return -ENOMEM;
 226         }
 227
 228         cpumask_copy(cpus_to_visit, cpu_possible_mask);
 229
 230         return cpufreq_register_notifier(&init_cpu_capacity_notifier,
 231                                          CPUFREQ_POLICY_NOTIFIER);
 232 }
 233 core_initcall(register_cpufreq_notifier);
 234
 235 static void __init parsing_done_workfn(struct work_struct *work)
 236 {
 237         cpufreq_unregister_notifier(&init_cpu_capacity_notifier,
 238                                          CPUFREQ_POLICY_NOTIFIER);
 239 }
 240
 241 #else
 242 core_initcall(free_raw_capacity);
 243 #endif