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, cpumask_t *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##_map); \ 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 static struct sysdev_class_attribute *cpu_state_attr[] = { 132 &attr_online_map, 133 &attr_possible_map, 134 &attr_present_map, 135 }; 136 137 static int cpu_states_init(void) 138 { 139 int i; 140 int err = 0; 141 142 for (i = 0; i < ARRAY_SIZE(cpu_state_attr); i++) { 143 int ret; 144 ret = sysdev_class_create_file(&cpu_sysdev_class, 145 cpu_state_attr[i]); 146 if (!err) 147 err = ret; 148 } 149 return err; 150 } 151 152 /* 153 * register_cpu - Setup a sysfs device for a CPU. 154 * @cpu - cpu->hotpluggable field set to 1 will generate a control file in 155 * sysfs for this CPU. 156 * @num - CPU number to use when creating the device. 157 * 158 * Initialize and register the CPU device. 159 */ 160 int __cpuinit register_cpu(struct cpu *cpu, int num) 161 { 162 int error; 163 cpu->node_id = cpu_to_node(num); 164 cpu->sysdev.id = num; 165 cpu->sysdev.cls = &cpu_sysdev_class; 166 167 error = sysdev_register(&cpu->sysdev); 168 169 if (!error && cpu->hotpluggable) 170 register_cpu_control(cpu); 171 if (!error) 172 per_cpu(cpu_sys_devices, num) = &cpu->sysdev; 173 if (!error) 174 register_cpu_under_node(num, cpu_to_node(num)); 175 176 #ifdef CONFIG_KEXEC 177 if (!error) 178 error = sysdev_create_file(&cpu->sysdev, &attr_crash_notes); 179 #endif 180 return error; 181 } 182 183 struct sys_device *get_cpu_sysdev(unsigned cpu) 184 { 185 if (cpu < nr_cpu_ids && cpu_possible(cpu)) 186 return per_cpu(cpu_sys_devices, cpu); 187 else 188 return NULL; 189 } 190 EXPORT_SYMBOL_GPL(get_cpu_sysdev); 191 192 int __init cpu_dev_init(void) 193 { 194 int err; 195 196 err = sysdev_class_register(&cpu_sysdev_class); 197 if (!err) 198 err = cpu_states_init(); 199 200 #if defined(CONFIG_SCHED_MC) || defined(CONFIG_SCHED_SMT) 201 if (!err) 202 err = sched_create_sysfs_power_savings_entries(&cpu_sysdev_class); 203 #endif 204 205 return err; 206 } 207