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/cpu.h> 9 #include <linux/topology.h> 10 #include <linux/device.h> 11 12 13 struct sysdev_class cpu_sysdev_class = { 14 set_kset_name("cpu"), 15 }; 16 EXPORT_SYMBOL(cpu_sysdev_class); 17 18 #ifdef CONFIG_HOTPLUG_CPU 19 int __attribute__((weak)) smp_prepare_cpu (int cpu) 20 { 21 return 0; 22 } 23 24 static ssize_t show_online(struct sys_device *dev, char *buf) 25 { 26 struct cpu *cpu = container_of(dev, struct cpu, sysdev); 27 28 return sprintf(buf, "%u\n", !!cpu_online(cpu->sysdev.id)); 29 } 30 31 static ssize_t store_online(struct sys_device *dev, const char *buf, 32 size_t count) 33 { 34 struct cpu *cpu = container_of(dev, struct cpu, sysdev); 35 ssize_t ret; 36 37 switch (buf[0]) { 38 case '0': 39 ret = cpu_down(cpu->sysdev.id); 40 if (!ret) 41 kobject_hotplug(&dev->kobj, KOBJ_OFFLINE); 42 break; 43 case '1': 44 ret = smp_prepare_cpu(cpu->sysdev.id); 45 if (!ret) 46 ret = cpu_up(cpu->sysdev.id); 47 if (!ret) 48 kobject_hotplug(&dev->kobj, KOBJ_ONLINE); 49 break; 50 default: 51 ret = -EINVAL; 52 } 53 54 if (ret >= 0) 55 ret = count; 56 return ret; 57 } 58 static SYSDEV_ATTR(online, 0600, show_online, store_online); 59 60 static void __devinit register_cpu_control(struct cpu *cpu) 61 { 62 sysdev_create_file(&cpu->sysdev, &attr_online); 63 } 64 void unregister_cpu(struct cpu *cpu, struct node *root) 65 { 66 67 if (root) 68 sysfs_remove_link(&root->sysdev.kobj, 69 kobject_name(&cpu->sysdev.kobj)); 70 sysdev_remove_file(&cpu->sysdev, &attr_online); 71 72 sysdev_unregister(&cpu->sysdev); 73 74 return; 75 } 76 #else /* ... !CONFIG_HOTPLUG_CPU */ 77 static inline void register_cpu_control(struct cpu *cpu) 78 { 79 } 80 #endif /* CONFIG_HOTPLUG_CPU */ 81 82 /* 83 * register_cpu - Setup a driverfs device for a CPU. 84 * @cpu - Callers can set the cpu->no_control field to 1, to indicate not to 85 * generate a control file in sysfs for this CPU. 86 * @num - CPU number to use when creating the device. 87 * 88 * Initialize and register the CPU device. 89 */ 90 int __devinit register_cpu(struct cpu *cpu, int num, struct node *root) 91 { 92 int error; 93 94 cpu->node_id = cpu_to_node(num); 95 cpu->sysdev.id = num; 96 cpu->sysdev.cls = &cpu_sysdev_class; 97 98 error = sysdev_register(&cpu->sysdev); 99 if (!error && root) 100 error = sysfs_create_link(&root->sysdev.kobj, 101 &cpu->sysdev.kobj, 102 kobject_name(&cpu->sysdev.kobj)); 103 if (!error && !cpu->no_control) 104 register_cpu_control(cpu); 105 return error; 106 } 107 108 109 110 int __init cpu_dev_init(void) 111 { 112 return sysdev_class_register(&cpu_sysdev_class); 113 } 114