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_uevent(&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_uevent(&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 #ifdef CONFIG_KEXEC 87 #include <linux/kexec.h> 88 89 static ssize_t show_crash_notes(struct sys_device *dev, char *buf) 90 { 91 struct cpu *cpu = container_of(dev, struct cpu, sysdev); 92 ssize_t rc; 93 unsigned long long addr; 94 int cpunum; 95 96 cpunum = cpu->sysdev.id; 97 98 /* 99 * Might be reading other cpu's data based on which cpu read thread 100 * has been scheduled. But cpu data (memory) is allocated once during 101 * boot up and this data does not change there after. Hence this 102 * operation should be safe. No locking required. 103 */ 104 addr = __pa(per_cpu_ptr(crash_notes, cpunum)); 105 rc = sprintf(buf, "%Lx\n", addr); 106 return rc; 107 } 108 static SYSDEV_ATTR(crash_notes, 0400, show_crash_notes, NULL); 109 #endif 110 111 /* 112 * register_cpu - Setup a driverfs device for a CPU. 113 * @cpu - Callers can set the cpu->no_control field to 1, to indicate not to 114 * generate a control file in sysfs for this CPU. 115 * @num - CPU number to use when creating the device. 116 * 117 * Initialize and register the CPU device. 118 */ 119 int __devinit register_cpu(struct cpu *cpu, int num, struct node *root) 120 { 121 int error; 122 123 cpu->node_id = cpu_to_node(num); 124 cpu->sysdev.id = num; 125 cpu->sysdev.cls = &cpu_sysdev_class; 126 127 error = sysdev_register(&cpu->sysdev); 128 if (!error && root) 129 error = sysfs_create_link(&root->sysdev.kobj, 130 &cpu->sysdev.kobj, 131 kobject_name(&cpu->sysdev.kobj)); 132 if (!error && !cpu->no_control) 133 register_cpu_control(cpu); 134 if (!error) 135 cpu_sys_devices[num] = &cpu->sysdev; 136 137 #ifdef CONFIG_KEXEC 138 if (!error) 139 error = sysdev_create_file(&cpu->sysdev, &attr_crash_notes); 140 #endif 141 return error; 142 } 143 144 struct sys_device *get_cpu_sysdev(int cpu) 145 { 146 if (cpu < NR_CPUS) 147 return cpu_sys_devices[cpu]; 148 else 149 return NULL; 150 } 151 EXPORT_SYMBOL_GPL(get_cpu_sysdev); 152 153 int __init cpu_dev_init(void) 154 { 155 return sysdev_class_register(&cpu_sysdev_class); 156 } 157