cpu.c revision 6c847402e1c69c1cfe2bddeadc8391bacbb3d0a5
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 16struct sysdev_class cpu_sysdev_class = { 17 .name = "cpu", 18}; 19EXPORT_SYMBOL(cpu_sysdev_class); 20 21static struct sys_device *cpu_sys_devices[NR_CPUS]; 22 23#ifdef CONFIG_HOTPLUG_CPU 24static 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 31static ssize_t __ref 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_uevent(&dev->kobj, KOBJ_OFFLINE); 42 break; 43 case '1': 44 ret = cpu_up(cpu->sysdev.id); 45 if (!ret) 46 kobject_uevent(&dev->kobj, KOBJ_ONLINE); 47 break; 48 default: 49 ret = -EINVAL; 50 } 51 52 if (ret >= 0) 53 ret = count; 54 return ret; 55} 56static SYSDEV_ATTR(online, 0644, show_online, store_online); 57 58static void __cpuinit register_cpu_control(struct cpu *cpu) 59{ 60 sysdev_create_file(&cpu->sysdev, &attr_online); 61} 62void unregister_cpu(struct cpu *cpu) 63{ 64 int logical_cpu = cpu->sysdev.id; 65 66 unregister_cpu_under_node(logical_cpu, cpu_to_node(logical_cpu)); 67 68 sysdev_remove_file(&cpu->sysdev, &attr_online); 69 70 sysdev_unregister(&cpu->sysdev); 71 cpu_sys_devices[logical_cpu] = NULL; 72 return; 73} 74#else /* ... !CONFIG_HOTPLUG_CPU */ 75static inline void register_cpu_control(struct cpu *cpu) 76{ 77} 78#endif /* CONFIG_HOTPLUG_CPU */ 79 80#ifdef CONFIG_KEXEC 81#include <linux/kexec.h> 82 83static ssize_t show_crash_notes(struct sys_device *dev, char *buf) 84{ 85 struct cpu *cpu = container_of(dev, struct cpu, sysdev); 86 ssize_t rc; 87 unsigned long long addr; 88 int cpunum; 89 90 cpunum = cpu->sysdev.id; 91 92 /* 93 * Might be reading other cpu's data based on which cpu read thread 94 * has been scheduled. But cpu data (memory) is allocated once during 95 * boot up and this data does not change there after. Hence this 96 * operation should be safe. No locking required. 97 */ 98 addr = __pa(per_cpu_ptr(crash_notes, cpunum)); 99 rc = sprintf(buf, "%Lx\n", addr); 100 return rc; 101} 102static SYSDEV_ATTR(crash_notes, 0400, show_crash_notes, NULL); 103#endif 104 105/* 106 * register_cpu - Setup a sysfs device for a CPU. 107 * @cpu - cpu->hotpluggable field set to 1 will generate a control file in 108 * sysfs for this CPU. 109 * @num - CPU number to use when creating the device. 110 * 111 * Initialize and register the CPU device. 112 */ 113int __cpuinit register_cpu(struct cpu *cpu, int num) 114{ 115 int error; 116 cpu->node_id = cpu_to_node(num); 117 cpu->sysdev.id = num; 118 cpu->sysdev.cls = &cpu_sysdev_class; 119 120 error = sysdev_register(&cpu->sysdev); 121 122 if (!error && cpu->hotpluggable) 123 register_cpu_control(cpu); 124 if (!error) 125 cpu_sys_devices[num] = &cpu->sysdev; 126 if (!error) 127 register_cpu_under_node(num, cpu_to_node(num)); 128 129#ifdef CONFIG_KEXEC 130 if (!error) 131 error = sysdev_create_file(&cpu->sysdev, &attr_crash_notes); 132#endif 133 return error; 134} 135 136struct sys_device *get_cpu_sysdev(unsigned cpu) 137{ 138 if (cpu < NR_CPUS) 139 return cpu_sys_devices[cpu]; 140 else 141 return NULL; 142} 143EXPORT_SYMBOL_GPL(get_cpu_sysdev); 144 145int __init cpu_dev_init(void) 146{ 147 int err; 148 149 err = sysdev_class_register(&cpu_sysdev_class); 150#if defined(CONFIG_SCHED_MC) || defined(CONFIG_SCHED_SMT) 151 if (!err) 152 err = sched_create_sysfs_power_savings_entries(&cpu_sysdev_class); 153#endif 154 155 return err; 156} 157