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 set_kset_name("cpu"), 18 }; 19 EXPORT_SYMBOL(cpu_sysdev_class); 20 21 static struct sys_device *cpu_sys_devices[NR_CPUS]; 22 23 #ifdef CONFIG_HOTPLUG_CPU 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_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 } 56 static SYSDEV_ATTR(online, 0600, show_online, store_online); 57 58 static void __devinit register_cpu_control(struct cpu *cpu) 59 { 60 sysdev_create_file(&cpu->sysdev, &attr_online); 61 } 62 void 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 */ 75 static 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 83 static 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 } 102 static 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 */ 113 int __devinit 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 } 135 136 struct 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 } 143 EXPORT_SYMBOL_GPL(get_cpu_sysdev); 144 145 int __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