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 DEFINE_PER_CPU(unsigned long, freq_scale) = SCHED_CAPACITY_SCALE;
  26
  27 void arch_set_freq_scale(struct cpumask *cpus, unsigned long cur_freq,
  28                          unsigned long max_freq)
  29 {
  30         unsigned long scale;
  31         int i;
  32
  33         scale = (cur_freq << SCHED_CAPACITY_SHIFT) / max_freq;
  34
  35         for_each_cpu(i, cpus)
  36                 per_cpu(freq_scale, i) = scale;
  37 }
  38
  39 static DEFINE_MUTEX(cpu_scale_mutex);
  40 DEFINE_PER_CPU(unsigned long, cpu_scale) = SCHED_CAPACITY_SCALE;
  41
  42 void topology_set_cpu_scale(unsigned int cpu, unsigned long capacity)
  43 {
  44         per_cpu(cpu_scale, cpu) = capacity;
  45 }
  46
  47 static ssize_t cpu_capacity_show(struct device *dev,
  48                                  struct device_attribute *attr,
  49                                  char *buf)
  50 {
  51         struct cpu *cpu = container_of(dev, struct cpu, dev);
  52
  53         return sprintf(buf, "%lu\n", topology_get_cpu_scale(NULL, cpu->dev.id));
  54 }
  55
  56 static ssize_t cpu_capacity_store(struct device *dev,
  57                                   struct device_attribute *attr,
  58                                   const char *buf,
  59                                   size_t count)
  60 {
  61         struct cpu *cpu = container_of(dev, struct cpu, dev);
  62         int this_cpu = cpu->dev.id;
  63         int i;
  64         unsigned long new_capacity;
  65         ssize_t ret;
  66
  67         if (!count)
  68                 return 0;
  69
  70         ret = kstrtoul(buf, 0, &new_capacity);
  71         if (ret)
  72                 return ret;
  73         if (new_capacity > SCHED_CAPACITY_SCALE)
  74                 return -EINVAL;
  75
  76         mutex_lock(&cpu_scale_mutex);
  77         for_each_cpu(i, &cpu_topology[this_cpu].core_sibling)
  78                 topology_set_cpu_scale(i, new_capacity);
  79         mutex_unlock(&cpu_scale_mutex);
  80
  81         return count;
  82 }
  83
  84 static DEVICE_ATTR_RW(cpu_capacity);
  85
  86 static int register_cpu_capacity_sysctl(void)
  87 {
  88         int i;
  89         struct device *cpu;
  90
  91         for_each_possible_cpu(i) {
  92                 cpu = get_cpu_device(i);
  93                 if (!cpu) {
  94                         pr_err("%s: too early to get CPU%d device!\n",
  95                                __func__, i);
  96                         continue;
  97                 }
  98                 device_create_file(cpu, &dev_attr_cpu_capacity);
  99         }
 100
 101         return 0;
 102 }
 103 subsys_initcall(register_cpu_capacity_sysctl);
 104
 105 static u32 capacity_scale;
 106 static u32 *raw_capacity;
 107
 108 static int free_raw_capacity(void)
 109 {
 110         kfree(raw_capacity);
 111         raw_capacity = NULL;
 112
 113         return 0;
 114 }
 115
 116 void topology_normalize_cpu_scale(void)
 117 {
 118         u64 capacity;
 119         int cpu;
 120
 121         if (!raw_capacity)
 122                 return;
 123
 124         pr_debug("cpu_capacity: capacity_scale=%u\n", capacity_scale);
 125         mutex_lock(&cpu_scale_mutex);
 126         for_each_possible_cpu(cpu) {
 127                 pr_debug("cpu_capacity: cpu=%d raw_capacity=%u\n",
 128                          cpu, raw_capacity[cpu]);
 129                 capacity = (raw_capacity[cpu] << SCHED_CAPACITY_SHIFT)
 130                         / capacity_scale;
 131                 topology_set_cpu_scale(cpu, capacity);
 132                 pr_debug("cpu_capacity: CPU%d cpu_capacity=%lu\n",
 133                         cpu, topology_get_cpu_scale(NULL, cpu));
 134         }
 135         mutex_unlock(&cpu_scale_mutex);
 136 }
 137
 138 bool __init topology_parse_cpu_capacity(struct device_node *cpu_node, int cpu)
 139 {
 140         static bool cap_parsing_failed;
 141         int ret;
 142         u32 cpu_capacity;
 143
 144         if (cap_parsing_failed)
 145                 return false;
 146
 147         ret = of_property_read_u32(cpu_node, "capacity-dmips-mhz",
 148                                    &cpu_capacity);
 149         if (!ret) {
 150                 if (!raw_capacity) {
 151                         raw_capacity = kcalloc(num_possible_cpus(),
 152                                                sizeof(*raw_capacity),
 153                                                GFP_KERNEL);
 154                         if (!raw_capacity) {
 155                                 pr_err("cpu_capacity: failed to allocate memory for raw capacities\n");
 156                                 cap_parsing_failed = true;
 157                                 return false;
 158                         }
 159                 }
 160                 capacity_scale = max(cpu_capacity, capacity_scale);
 161                 raw_capacity[cpu] = cpu_capacity;
 162                 pr_debug("cpu_capacity: %pOF cpu_capacity=%u (raw)\n",
 163                         cpu_node, raw_capacity[cpu]);
 164         } else {
 165                 if (raw_capacity) {
 166                         pr_err("cpu_capacity: missing %pOF raw capacity\n",
 167                                 cpu_node);
 168                         pr_err("cpu_capacity: partial information: fallback to 1024 for all CPUs\n");
 169                 }
 170                 cap_parsing_failed = true;
 171                 free_raw_capacity();
 172         }
 173
 174         return !ret;
 175 }
 176
 177 #ifdef CONFIG_CPU_FREQ
 178 static cpumask_var_t cpus_to_visit __initdata;
 179 static void __init parsing_done_workfn(struct work_struct *work);
 180 static __initdata DECLARE_WORK(parsing_done_work, parsing_done_workfn);
 181
 182 static int __init
 183 init_cpu_capacity_callback(struct notifier_block *nb,
 184                            unsigned long val,
 185                            void *data)
 186 {
 187         struct cpufreq_policy *policy = data;
 188         int cpu;
 189
 190         if (!raw_capacity)
 191                 return 0;
 192
 193         if (val != CPUFREQ_NOTIFY)
 194                 return 0;
 195
 196         pr_debug("cpu_capacity: init cpu capacity for CPUs [%*pbl] (to_visit=%*pbl)\n",
 197                  cpumask_pr_args(policy->related_cpus),
 198                  cpumask_pr_args(cpus_to_visit));
 199
 200         cpumask_andnot(cpus_to_visit, cpus_to_visit, policy->related_cpus);
 201
 202         for_each_cpu(cpu, policy->related_cpus) {
 203                 raw_capacity[cpu] = topology_get_cpu_scale(NULL, cpu) *
 204                                     policy->cpuinfo.max_freq / 1000UL;
 205                 capacity_scale = max(raw_capacity[cpu], capacity_scale);
 206         }
 207
 208         if (cpumask_empty(cpus_to_visit)) {
 209                 topology_normalize_cpu_scale();
 210                 free_raw_capacity();
 211                 pr_debug("cpu_capacity: parsing done\n");
 212                 schedule_work(&parsing_done_work);
 213         }
 214
 215         return 0;
 216 }
 217
 218 static struct notifier_block init_cpu_capacity_notifier __initdata = {
 219         .notifier_call = init_cpu_capacity_callback,
 220 };
 221
 222 static int __init register_cpufreq_notifier(void)
 223 {
 224         int ret;
 225
 226         /*
 227          * on ACPI-based systems we need to use the default cpu capacity
 228          * until we have the necessary code to parse the cpu capacity, so
 229          * skip registering cpufreq notifier.
 230          */
 231         if (!acpi_disabled || !raw_capacity)
 232                 return -EINVAL;
 233
 234         if (!alloc_cpumask_var(&cpus_to_visit, GFP_KERNEL)) {
 235                 pr_err("cpu_capacity: failed to allocate memory for cpus_to_visit\n");
 236                 return -ENOMEM;
 237         }
 238
 239         cpumask_copy(cpus_to_visit, cpu_possible_mask);
 240
 241         ret = cpufreq_register_notifier(&init_cpu_capacity_notifier,
 242                                         CPUFREQ_POLICY_NOTIFIER);
 243
 244         if (ret)
 245                 free_cpumask_var(cpus_to_visit);
 246
 247         return ret;
 248 }
 249 core_initcall(register_cpufreq_notifier);
 250
 251 static void __init parsing_done_workfn(struct work_struct *work)
 252 {
 253         cpufreq_unregister_notifier(&init_cpu_capacity_notifier,
 254                                          CPUFREQ_POLICY_NOTIFIER);
 255         free_cpumask_var(cpus_to_visit);
 256 }
 257
 258 #else
 259 core_initcall(free_raw_capacity);
 260 #endif