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 static ssize_t show_online(struct sys_device *dev, char *buf) 23 { 24 struct cpu *cpu = container_of(dev, struct cpu, sysdev); 25 26 return sprintf(buf, "%u\n", !!cpu_online(cpu->sysdev.id)); 27 } 28 29 static ssize_t store_online(struct sys_device *dev, const char *buf, 30 size_t count) 31 { 32 struct cpu *cpu = container_of(dev, struct cpu, sysdev); 33 ssize_t ret; 34 35 switch (buf[0]) { 36 case '0': 37 ret = cpu_down(cpu->sysdev.id); 38 if (!ret) 39 kobject_uevent(&dev->kobj, KOBJ_OFFLINE); 40 break; 41 case '1': 42 ret = cpu_up(cpu->sysdev.id); 43 if (!ret) 44 kobject_uevent(&dev->kobj, KOBJ_ONLINE); 45 break; 46 default: 47 ret = -EINVAL; 48 } 49 50 if (ret >= 0) 51 ret = count; 52 return ret; 53 } 54 static SYSDEV_ATTR(online, 0600, show_online, store_online); 55 56 static void __devinit register_cpu_control(struct cpu *cpu) 57 { 58 sysdev_create_file(&cpu->sysdev, &attr_online); 59 } 60 void unregister_cpu(struct cpu *cpu, struct node *root) 61 { 62 int logical_cpu = cpu->sysdev.id; 63 64 if (root) 65 sysfs_remove_link(&root->sysdev.kobj, 66 kobject_name(&cpu->sysdev.kobj)); 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, struct node *root) 113 { 114 int error; 115 116 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 if (!error && root) 122 error = sysfs_create_link(&root->sysdev.kobj, 123 &cpu->sysdev.kobj, 124 kobject_name(&cpu->sysdev.kobj)); 125 if (!error && !cpu->no_control) 126 register_cpu_control(cpu); 127 if (!error) 128 cpu_sys_devices[num] = &cpu->sysdev; 129 130 #ifdef CONFIG_KEXEC 131 if (!error) 132 error = sysdev_create_file(&cpu->sysdev, &attr_crash_notes); 133 #endif 134 return error; 135 } 136 137 struct sys_device *get_cpu_sysdev(unsigned cpu) 138 { 139 if (cpu < NR_CPUS) 140 return cpu_sys_devices[cpu]; 141 else 142 return NULL; 143 } 144 EXPORT_SYMBOL_GPL(get_cpu_sysdev); 145 146 int __init cpu_dev_init(void) 147 { 148 return sysdev_class_register(&cpu_sysdev_class); 149 } 150