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; 170 static void parsing_done_workfn(struct work_struct *work); 171 static DECLARE_WORK(parsing_done_work, parsing_done_workfn); 172 173 static int 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 = { 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 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 244