drivers/base/cpu.c

   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_hotplug(&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_hotplug(&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 /*
  87  * register_cpu - Setup a driverfs device for a CPU.
  88  * @cpu - Callers can set the cpu->no_control field to 1, to indicate not to
  89  *                generate a control file in sysfs for this CPU.
  90  * @num - CPU number to use when creating the device.
  91  *
  92  * Initialize and register the CPU device.
  93  */
  94 int __devinit register_cpu(struct cpu *cpu, int num, struct node *root)
  95 {
  96         int error;
  97
  98         cpu->node_id = cpu_to_node(num);
  99         cpu->sysdev.id = num;
 100         cpu->sysdev.cls = &cpu_sysdev_class;
 101
 102         error = sysdev_register(&cpu->sysdev);
 103         if (!error && root)
 104                 error = sysfs_create_link(&root->sysdev.kobj,
 105                                           &cpu->sysdev.kobj,
 106                                           kobject_name(&cpu->sysdev.kobj));
 107         if (!error && !cpu->no_control)
 108                 register_cpu_control(cpu);
 109         if (!error)
 110                 cpu_sys_devices[num] = &cpu->sysdev;
 111         return error;
 112 }
 113
 114 struct sys_device *get_cpu_sysdev(int cpu)
 115 {
 116         if (cpu < NR_CPUS)
 117                 return cpu_sys_devices[cpu];
 118         else
 119                 return NULL;
 120 }
 121 EXPORT_SYMBOL_GPL(get_cpu_sysdev);
 122
 123 int __init cpu_dev_init(void)
 124 {
 125         return sysdev_class_register(&cpu_sysdev_class);
 126 }