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 244