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 #include <linux/node.h> 12 13 #include "base.h" 14 15 struct sysdev_class cpu_sysdev_class = { 16 set_kset_name("cpu"), 17 }; 18 EXPORT_SYMBOL(cpu_sysdev_class); 19 20 static struct sys_device *cpu_sys_devices[NR_CPUS]; 21 22 #ifdef CONFIG_HOTPLUG_CPU 23 static ssize_t show_online(struct sys_device *dev, char *buf) 24 { 25 struct cpu *cpu = container_of(dev, struct cpu, sysdev); 26 27 return sprintf(buf, "%u\n", !!cpu_online(cpu->sysdev.id)); 28 } 29 30 static ssize_t store_online(struct sys_device *dev, const char *buf, 31 size_t count) 32 { 33 struct cpu *cpu = container_of(dev, struct cpu, sysdev); 34 ssize_t ret; 35 36 switch (buf[0]) { 37 case '0': 38 ret = cpu_down(cpu->sysdev.id); 39 if (!ret) 40 kobject_uevent(&dev->kobj, KOBJ_OFFLINE); 41 break; 42 case '1': 43 ret = cpu_up(cpu->sysdev.id); 44 if (!ret) 45 kobject_uevent(&dev->kobj, KOBJ_ONLINE); 46 break; 47 default: 48 ret = -EINVAL; 49 } 50 51 if (ret >= 0) 52 ret = count; 53 return ret; 54 } 55 static SYSDEV_ATTR(online, 0600, show_online, store_online); 56 57 static void __devinit register_cpu_control(struct cpu *cpu) 58 { 59 sysdev_create_file(&cpu->sysdev, &attr_online); 60 } 61 void unregister_cpu(struct cpu *cpu) 62 { 63 int logical_cpu = cpu->sysdev.id; 64 65 unregister_cpu_under_node(logical_cpu, cpu_to_node(logical_cpu)); 66 67 sysdev_remove_file(&cpu->sysdev, &attr_online); 68 69 sysdev_unregister(&cpu->sysdev); 70 cpu_sys_devices[logical_cpu] = NULL; 71 return; 72 } 73 #else /* ... !CONFIG_HOTPLUG_CPU */ 74 static inline void register_cpu_control(struct cpu *cpu) 75 { 76 } 77 #endif /* CONFIG_HOTPLUG_CPU */ 78 79 #ifdef CONFIG_KEXEC 80 #include <linux/kexec.h> 81 82 static ssize_t show_crash_notes(struct sys_device *dev, char *buf) 83 { 84 struct cpu *cpu = container_of(dev, struct cpu, sysdev); 85 ssize_t rc; 86 unsigned long long addr; 87 int cpunum; 88 89 cpunum = cpu->sysdev.id; 90 91 /* 92 * Might be reading other cpu's data based on which cpu read thread 93 * has been scheduled. But cpu data (memory) is allocated once during 94 * boot up and this data does not change there after. Hence this 95 * operation should be safe. No locking required. 96 */ 97 addr = __pa(per_cpu_ptr(crash_notes, cpunum)); 98 rc = sprintf(buf, "%Lx\n", addr); 99 return rc; 100 } 101 static SYSDEV_ATTR(crash_notes, 0400, show_crash_notes, NULL); 102 #endif 103 104 /* 105 * register_cpu - Setup a driverfs device for a CPU. 106 * @cpu - Callers can set the cpu->no_control field to 1, to indicate not to 107 * generate a control file in sysfs for this CPU. 108 * @num - CPU number to use when creating the device. 109 * 110 * Initialize and register the CPU device. 111 */ 112 int __devinit register_cpu(struct cpu *cpu, int num) 113 { 114 int error; 115 cpu->node_id = cpu_to_node(num); 116 cpu->sysdev.id = num; 117 cpu->sysdev.cls = &cpu_sysdev_class; 118 119 error = sysdev_register(&cpu->sysdev); 120 121 if (!error && !cpu->no_control) 122 register_cpu_control(cpu); 123 if (!error) 124 cpu_sys_devices[num] = &cpu->sysdev; 125 if (!error) 126 register_cpu_under_node(num, cpu_to_node(num)); 127 128 #ifdef CONFIG_KEXEC 129 if (!error) 130 error = sysdev_create_file(&cpu->sysdev, &attr_crash_notes); 131 #endif 132 return error; 133 } 134 135 struct sys_device *get_cpu_sysdev(unsigned cpu) 136 { 137 if (cpu < NR_CPUS) 138 return cpu_sys_devices[cpu]; 139 else 140 return NULL; 141 } 142 EXPORT_SYMBOL_GPL(get_cpu_sysdev); 143 144 int __init cpu_dev_init(void) 145 { 146 int err; 147 148 err = sysdev_class_register(&cpu_sysdev_class); 149 #if defined(CONFIG_SCHED_MC) || defined(CONFIG_SCHED_SMT) 150 if (!err) 151 err = sched_create_sysfs_power_savings_entries(&cpu_sysdev_class); 152 #endif 153 154 return err; 155 } 156