1 /* 2 * drivers/base/cpu.c - basic CPU class support 3 */ 4 5 #include <linux/sysdev.h> 6 #include <linux/module.h> 7 #include <linux/init.h> 8 #include <linux/sched.h> 9 #include <linux/cpu.h> 10 #include <linux/topology.h> 11 #include <linux/device.h> 12 #include <linux/node.h> 13 14 #include "base.h" 15 16 struct sysdev_class cpu_sysdev_class = { 17 .name = "cpu", 18 }; 19 EXPORT_SYMBOL(cpu_sysdev_class); 20 21 static DEFINE_PER_CPU(struct sys_device *, cpu_sys_devices); 22 23 #ifdef CONFIG_HOTPLUG_CPU 24 static ssize_t show_online(struct sys_device *dev, struct sysdev_attribute *attr, 25 char *buf) 26 { 27 struct cpu *cpu = container_of(dev, struct cpu, sysdev); 28 29 return sprintf(buf, "%u\n", !!cpu_online(cpu->sysdev.id)); 30 } 31 32 static ssize_t __ref store_online(struct sys_device *dev, struct sysdev_attribute *attr, 33 const char *buf, size_t count) 34 { 35 struct cpu *cpu = container_of(dev, struct cpu, sysdev); 36 ssize_t ret; 37 38 switch (buf[0]) { 39 case '0': 40 ret = cpu_down(cpu->sysdev.id); 41 if (!ret) 42 kobject_uevent(&dev->kobj, KOBJ_OFFLINE); 43 break; 44 case '1': 45 ret = cpu_up(cpu->sysdev.id); 46 if (!ret) 47 kobject_uevent(&dev->kobj, KOBJ_ONLINE); 48 break; 49 default: 50 ret = -EINVAL; 51 } 52 53 if (ret >= 0) 54 ret = count; 55 return ret; 56 } 57 static SYSDEV_ATTR(online, 0644, show_online, store_online); 58 59 static void __cpuinit register_cpu_control(struct cpu *cpu) 60 { 61 sysdev_create_file(&cpu->sysdev, &attr_online); 62 } 63 void unregister_cpu(struct cpu *cpu) 64 { 65 int logical_cpu = cpu->sysdev.id; 66 67 unregister_cpu_under_node(logical_cpu, cpu_to_node(logical_cpu)); 68 69 sysdev_remove_file(&cpu->sysdev, &attr_online); 70 71 sysdev_unregister(&cpu->sysdev); 72 per_cpu(cpu_sys_devices, logical_cpu) = NULL; 73 return; 74 } 75 #else /* ... !CONFIG_HOTPLUG_CPU */ 76 static inline void register_cpu_control(struct cpu *cpu) 77 { 78 } 79 #endif /* CONFIG_HOTPLUG_CPU */ 80 81 #ifdef CONFIG_KEXEC 82 #include <linux/kexec.h> 83 84 static ssize_t show_crash_notes(struct sys_device *dev, struct sysdev_attribute *attr, 85 char *buf) 86 { 87 struct cpu *cpu = container_of(dev, struct cpu, sysdev); 88 ssize_t rc; 89 unsigned long long addr; 90 int cpunum; 91 92 cpunum = cpu->sysdev.id; 93 94 /* 95 * Might be reading other cpu's data based on which cpu read thread 96 * has been scheduled. But cpu data (memory) is allocated once during 97 * boot up and this data does not change there after. Hence this 98 * operation should be safe. No locking required. 99 */ 100 addr = __pa(per_cpu_ptr(crash_notes, cpunum)); 101 rc = sprintf(buf, "%Lx\n", addr); 102 return rc; 103 } 104 static SYSDEV_ATTR(crash_notes, 0400, show_crash_notes, NULL); 105 #endif 106 107 /* 108 * Print cpu online, possible, present, and system maps 109 */ 110 static ssize_t print_cpus_map(char *buf, const struct cpumask *map) 111 { 112 int n = cpulist_scnprintf(buf, PAGE_SIZE-2, map); 113 114 buf[n++] = '\n'; 115 buf[n] = '\0'; 116 return n; 117 } 118 119 #define print_cpus_func(type) \ 120 static ssize_t print_cpus_##type(struct sysdev_class *class, char *buf) \ 121 { \ 122 return print_cpus_map(buf, cpu_##type##_mask); \ 123 } \ 124 static struct sysdev_class_attribute attr_##type##_map = \ 125 _SYSDEV_CLASS_ATTR(type, 0444, print_cpus_##type, NULL) 126 127 print_cpus_func(online); 128 print_cpus_func(possible); 129 print_cpus_func(present); 130 131 /* 132 * Print values for NR_CPUS and offlined cpus 133 */ 134 static ssize_t print_cpus_kernel_max(struct sysdev_class *class, char *buf) 135 { 136 int n = snprintf(buf, PAGE_SIZE-2, "%d\n", NR_CPUS - 1); 137 return n; 138 } 139 static SYSDEV_CLASS_ATTR(kernel_max, 0444, print_cpus_kernel_max, NULL); 140 141 /* arch-optional setting to enable display of offline cpus >= nr_cpu_ids */ 142 unsigned int total_cpus; 143 144 static ssize_t print_cpus_offline(struct sysdev_class *class, char *buf) 145 { 146 int n = 0, len = PAGE_SIZE-2; 147 cpumask_var_t offline; 148 149 /* display offline cpus < nr_cpu_ids */ 150 if (!alloc_cpumask_var(&offline, GFP_KERNEL)) 151 return -ENOMEM; 152 cpumask_complement(offline, cpu_online_mask); 153 n = cpulist_scnprintf(buf, len, offline); 154 free_cpumask_var(offline); 155 156 /* display offline cpus >= nr_cpu_ids */ 157 if (total_cpus && nr_cpu_ids < total_cpus) { 158 if (n && n < len) 159 buf[n++] = ','; 160 161 if (nr_cpu_ids == total_cpus-1) 162 n += snprintf(&buf[n], len - n, "%d", nr_cpu_ids); 163 else 164 n += snprintf(&buf[n], len - n, "%d-%d", 165 nr_cpu_ids, total_cpus-1); 166 } 167 168 n += snprintf(&buf[n], len - n, "\n"); 169 return n; 170 } 171 static SYSDEV_CLASS_ATTR(offline, 0444, print_cpus_offline, NULL); 172 173 static struct sysdev_class_attribute *cpu_state_attr[] = { 174 &attr_online_map, 175 &attr_possible_map, 176 &attr_present_map, 177 &attr_kernel_max, 178 &attr_offline, 179 }; 180 181 static int cpu_states_init(void) 182 { 183 int i; 184 int err = 0; 185 186 for (i = 0; i < ARRAY_SIZE(cpu_state_attr); i++) { 187 int ret; 188 ret = sysdev_class_create_file(&cpu_sysdev_class, 189 cpu_state_attr[i]); 190 if (!err) 191 err = ret; 192 } 193 return err; 194 } 195 196 /* 197 * register_cpu - Setup a sysfs device for a CPU. 198 * @cpu - cpu->hotpluggable field set to 1 will generate a control file in 199 * sysfs for this CPU. 200 * @num - CPU number to use when creating the device. 201 * 202 * Initialize and register the CPU device. 203 */ 204 int __cpuinit register_cpu(struct cpu *cpu, int num) 205 { 206 int error; 207 cpu->node_id = cpu_to_node(num); 208 cpu->sysdev.id = num; 209 cpu->sysdev.cls = &cpu_sysdev_class; 210 211 error = sysdev_register(&cpu->sysdev); 212 213 if (!error && cpu->hotpluggable) 214 register_cpu_control(cpu); 215 if (!error) 216 per_cpu(cpu_sys_devices, num) = &cpu->sysdev; 217 if (!error) 218 register_cpu_under_node(num, cpu_to_node(num)); 219 220 #ifdef CONFIG_KEXEC 221 if (!error) 222 error = sysdev_create_file(&cpu->sysdev, &attr_crash_notes); 223 #endif 224 return error; 225 } 226 227 struct sys_device *get_cpu_sysdev(unsigned cpu) 228 { 229 if (cpu < nr_cpu_ids && cpu_possible(cpu)) 230 return per_cpu(cpu_sys_devices, cpu); 231 else 232 return NULL; 233 } 234 EXPORT_SYMBOL_GPL(get_cpu_sysdev); 235 236 int __init cpu_dev_init(void) 237 { 238 int err; 239 240 err = sysdev_class_register(&cpu_sysdev_class); 241 if (!err) 242 err = cpu_states_init(); 243 244 #if defined(CONFIG_SCHED_MC) || defined(CONFIG_SCHED_SMT) 245 if (!err) 246 err = sched_create_sysfs_power_savings_entries(&cpu_sysdev_class); 247 #endif 248 249 return err; 250 } 251