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 #include "base.h" 13 14 struct sysdev_class cpu_sysdev_class = { 15 set_kset_name("cpu"), 16 }; 17 EXPORT_SYMBOL(cpu_sysdev_class); 18 19 static struct sys_device *cpu_sys_devices[NR_CPUS]; 20 21 #ifdef CONFIG_HOTPLUG_CPU 22 int __attribute__((weak)) smp_prepare_cpu (int cpu) 23 { 24 return 0; 25 } 26 27 static ssize_t show_online(struct sys_device *dev, char *buf) 28 { 29 struct cpu *cpu = container_of(dev, struct cpu, sysdev); 30 31 return sprintf(buf, "%u\n", !!cpu_online(cpu->sysdev.id)); 32 } 33 34 static ssize_t store_online(struct sys_device *dev, const char *buf, 35 size_t count) 36 { 37 struct cpu *cpu = container_of(dev, struct cpu, sysdev); 38 ssize_t ret; 39 40 switch (buf[0]) { 41 case '0': 42 ret = cpu_down(cpu->sysdev.id); 43 if (!ret) 44 kobject_hotplug(&dev->kobj, KOBJ_OFFLINE); 45 break; 46 case '1': 47 ret = smp_prepare_cpu(cpu->sysdev.id); 48 if (!ret) 49 ret = cpu_up(cpu->sysdev.id); 50 if (!ret) 51 kobject_hotplug(&dev->kobj, KOBJ_ONLINE); 52 break; 53 default: 54 ret = -EINVAL; 55 } 56 57 if (ret >= 0) 58 ret = count; 59 return ret; 60 } 61 static SYSDEV_ATTR(online, 0600, show_online, store_online); 62 63 static void __devinit register_cpu_control(struct cpu *cpu) 64 { 65 sysdev_create_file(&cpu->sysdev, &attr_online); 66 } 67 void unregister_cpu(struct cpu *cpu, struct node *root) 68 { 69 int logical_cpu = cpu->sysdev.id; 70 71 if (root) 72 sysfs_remove_link(&root->sysdev.kobj, 73 kobject_name(&cpu->sysdev.kobj)); 74 sysdev_remove_file(&cpu->sysdev, &attr_online); 75 76 sysdev_unregister(&cpu->sysdev); 77 cpu_sys_devices[logical_cpu] = NULL; 78 return; 79 } 80 #else /* ... !CONFIG_HOTPLUG_CPU */ 81 static inline void register_cpu_control(struct cpu *cpu) 82 { 83 } 84 #endif /* CONFIG_HOTPLUG_CPU */ 85 86 /* 87 * register_cpu - Setup a driverfs device for a CPU. 88 * @cpu - Callers can set the cpu->no_control field to 1, to indicate not to 89 * generate a control file in sysfs for this CPU. 90 * @num - CPU number to use when creating the device. 91 * 92 * Initialize and register the CPU device. 93 */ 94 int __devinit register_cpu(struct cpu *cpu, int num, struct node *root) 95 { 96 int error; 97 98 cpu->node_id = cpu_to_node(num); 99 cpu->sysdev.id = num; 100 cpu->sysdev.cls = &cpu_sysdev_class; 101 102 error = sysdev_register(&cpu->sysdev); 103 if (!error && root) 104 error = sysfs_create_link(&root->sysdev.kobj, 105 &cpu->sysdev.kobj, 106 kobject_name(&cpu->sysdev.kobj)); 107 if (!error && !cpu->no_control) 108 register_cpu_control(cpu); 109 if (!error) 110 cpu_sys_devices[num] = &cpu->sysdev; 111 return error; 112 } 113 114 struct sys_device *get_cpu_sysdev(int cpu) 115 { 116 if (cpu < NR_CPUS) 117 return cpu_sys_devices[cpu]; 118 else 119 return NULL; 120 } 121 EXPORT_SYMBOL_GPL(get_cpu_sysdev); 122 123 int __init cpu_dev_init(void) 124 { 125 return sysdev_class_register(&cpu_sysdev_class); 126 } 127