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 #ifdef CONFIG_HOTPLUG_CPU
  20 int __attribute__((weak)) smp_prepare_cpu (int cpu)
  21 {
  22         return 0;
  23 }
  24
  25 static ssize_t show_online(struct sys_device *dev, char *buf)
  26 {
  27         struct cpu *cpu = container_of(dev, struct cpu, sysdev);
  28
  29         return sprintf(buf, "%u\n", !!cpu_online(cpu->sysdev.id));
  30 }
  31
  32 static ssize_t store_online(struct sys_device *dev, const char *buf,
  33                             size_t count)
  34 {
  35         struct cpu *cpu = container_of(dev, struct cpu, sysdev);
  36         ssize_t ret;
  37
  38         switch (buf[0]) {
  39         case '0':
  40                 ret = cpu_down(cpu->sysdev.id);
  41                 if (!ret)
  42                         kobject_hotplug(&dev->kobj, KOBJ_OFFLINE);
  43                 break;
  44         case '1':
  45                 ret = smp_prepare_cpu(cpu->sysdev.id);
  46                 if (!ret)
  47                         ret = cpu_up(cpu->sysdev.id);
  48                 if (!ret)
  49                         kobject_hotplug(&dev->kobj, KOBJ_ONLINE);
  50                 break;
  51         default:
  52                 ret = -EINVAL;
  53         }
  54
  55         if (ret >= 0)
  56                 ret = count;
  57         return ret;
  58 }
  59 static SYSDEV_ATTR(online, 0600, show_online, store_online);
  60
  61 static void __devinit register_cpu_control(struct cpu *cpu)
  62 {
  63         sysdev_create_file(&cpu->sysdev, &attr_online);
  64 }
  65 void unregister_cpu(struct cpu *cpu, struct node *root)
  66 {
  67
  68         if (root)
  69                 sysfs_remove_link(&root->sysdev.kobj,
  70                                   kobject_name(&cpu->sysdev.kobj));
  71         sysdev_remove_file(&cpu->sysdev, &attr_online);
  72
  73         sysdev_unregister(&cpu->sysdev);
  74
  75         return;
  76 }
  77 #else /* ... !CONFIG_HOTPLUG_CPU */
  78 static inline void register_cpu_control(struct cpu *cpu)
  79 {
  80 }
  81 #endif /* CONFIG_HOTPLUG_CPU */
  82
  83 /*
  84  * register_cpu - Setup a driverfs device for a CPU.
  85  * @cpu - Callers can set the cpu->no_control field to 1, to indicate not to
  86  *                generate a control file in sysfs for this CPU.
  87  * @num - CPU number to use when creating the device.
  88  *
  89  * Initialize and register the CPU device.
  90  */
  91 int __devinit register_cpu(struct cpu *cpu, int num, struct node *root)
  92 {
  93         int error;
  94
  95         cpu->node_id = cpu_to_node(num);
  96         cpu->sysdev.id = num;
  97         cpu->sysdev.cls = &cpu_sysdev_class;
  98
  99         error = sysdev_register(&cpu->sysdev);
 100         if (!error && root)
 101                 error = sysfs_create_link(&root->sysdev.kobj,
 102                                           &cpu->sysdev.kobj,
 103                                           kobject_name(&cpu->sysdev.kobj));
 104         if (!error && !cpu->no_control)
 105                 register_cpu_control(cpu);
 106         return error;
 107 }
 108
 109
 110
 111 int __init cpu_dev_init(void)
 112 {
 113         return sysdev_class_register(&cpu_sysdev_class);
 114 }