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
  13 struct sysdev_class cpu_sysdev_class = {
  14         set_kset_name("cpu"),
  15 };
  16 EXPORT_SYMBOL(cpu_sysdev_class);
  17
  18 #ifdef CONFIG_HOTPLUG_CPU
  19 int __attribute__((weak)) smp_prepare_cpu (int cpu)
  20 {
  21         return 0;
  22 }
  23
  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_hotplug(&dev->kobj, KOBJ_OFFLINE);
  42                 break;
  43         case '1':
  44                 ret = smp_prepare_cpu(cpu->sysdev.id);
  45                 if (!ret)
  46                         ret = cpu_up(cpu->sysdev.id);
  47                 if (!ret)
  48                         kobject_hotplug(&dev->kobj, KOBJ_ONLINE);
  49                 break;
  50         default:
  51                 ret = -EINVAL;
  52         }
  53
  54         if (ret >= 0)
  55                 ret = count;
  56         return ret;
  57 }
  58 static SYSDEV_ATTR(online, 0600, show_online, store_online);
  59
  60 static void __devinit register_cpu_control(struct cpu *cpu)
  61 {
  62         sysdev_create_file(&cpu->sysdev, &attr_online);
  63 }
  64 void unregister_cpu(struct cpu *cpu, struct node *root)
  65 {
  66
  67         if (root)
  68                 sysfs_remove_link(&root->sysdev.kobj,
  69                                   kobject_name(&cpu->sysdev.kobj));
  70         sysdev_remove_file(&cpu->sysdev, &attr_online);
  71
  72         sysdev_unregister(&cpu->sysdev);
  73
  74         return;
  75 }
  76 #else /* ... !CONFIG_HOTPLUG_CPU */
  77 static inline void register_cpu_control(struct cpu *cpu)
  78 {
  79 }
  80 #endif /* CONFIG_HOTPLUG_CPU */
  81
  82 /*
  83  * register_cpu - Setup a driverfs device for a CPU.
  84  * @cpu - Callers can set the cpu->no_control field to 1, to indicate not to
  85  *                generate a control file in sysfs for this CPU.
  86  * @num - CPU number to use when creating the device.
  87  *
  88  * Initialize and register the CPU device.
  89  */
  90 int __devinit register_cpu(struct cpu *cpu, int num, struct node *root)
  91 {
  92         int error;
  93
  94         cpu->node_id = cpu_to_node(num);
  95         cpu->sysdev.id = num;
  96         cpu->sysdev.cls = &cpu_sysdev_class;
  97
  98         error = sysdev_register(&cpu->sysdev);
  99         if (!error && root)
 100                 error = sysfs_create_link(&root->sysdev.kobj,
 101                                           &cpu->sysdev.kobj,
 102                                           kobject_name(&cpu->sysdev.kobj));
 103         if (!error && !cpu->no_control)
 104                 register_cpu_control(cpu);
 105         return error;
 106 }
 107
 108
 109
 110 int __init cpu_dev_init(void)
 111 {
 112         return sysdev_class_register(&cpu_sysdev_class);
 113 }