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