include/linux/cpu.h

   1 /*
   2  * include/linux/cpu.h - generic cpu definition
   3  *
   4  * This is mainly for topological representation. We define the
   5  * basic 'struct cpu' here, which can be embedded in per-arch
   6  * definitions of processors.
   7  *
   8  * Basic handling of the devices is done in drivers/base/cpu.c
   9  * and system devices are handled in drivers/base/sys.c.
  10  *
  11  * CPUs are exported via sysfs in the class/cpu/devices/
  12  * directory.
  13  *
  14  * Per-cpu interfaces can be implemented using a struct device_interface.
  15  * See the following for how to do this:
  16  * - drivers/base/intf.c
  17  * - Documentation/driver-model/interface.txt
  18  */
  19 #ifndef _LINUX_CPU_H_
  20 #define _LINUX_CPU_H_
  21
  22 #include <linux/sysdev.h>
  23 #include <linux/node.h>
  24 #include <linux/compiler.h>
  25 #include <linux/cpumask.h>
  26 #include <asm/semaphore.h>
  27
  28 struct cpu {
  29         int node_id;            /* The node which contains the CPU */
  30         int no_control;         /* Should the sysfs control file be created? */
  31         struct sys_device sysdev;
  32 };
  33
  34 extern int register_cpu(struct cpu *, int, struct node *);
  35 #ifdef CONFIG_HOTPLUG_CPU
  36 extern void unregister_cpu(struct cpu *, struct node *);
  37 #endif
  38 struct notifier_block;
  39
  40 #ifdef CONFIG_SMP
  41 /* Need to know about CPUs going up/down? */
  42 extern int register_cpu_notifier(struct notifier_block *nb);
  43 extern void unregister_cpu_notifier(struct notifier_block *nb);
  44
  45 int cpu_up(unsigned int cpu);
  46
  47 #else
  48
  49 static inline int register_cpu_notifier(struct notifier_block *nb)
  50 {
  51         return 0;
  52 }
  53 static inline void unregister_cpu_notifier(struct notifier_block *nb)
  54 {
  55 }
  56
  57 #endif /* CONFIG_SMP */
  58 extern struct sysdev_class cpu_sysdev_class;
  59
  60 #ifdef CONFIG_HOTPLUG_CPU
  61 /* Stop CPUs going up and down. */
  62 extern struct semaphore cpucontrol;
  63 #define lock_cpu_hotplug()      down(&cpucontrol)
  64 #define unlock_cpu_hotplug()    up(&cpucontrol)
  65 #define lock_cpu_hotplug_interruptible() down_interruptible(&cpucontrol)
  66 #define hotcpu_notifier(fn, pri) {                              \
  67         static struct notifier_block fn##_nb =                  \
  68                 { .notifier_call = fn, .priority = pri };       \
  69         register_cpu_notifier(&fn##_nb);                        \
  70 }
  71 int cpu_down(unsigned int cpu);
  72 extern int __attribute__((weak)) smp_prepare_cpu(int cpu);
  73 #define cpu_is_offline(cpu) unlikely(!cpu_online(cpu))
  74 #else
  75 #define lock_cpu_hotplug()      do { } while (0)
  76 #define unlock_cpu_hotplug()    do { } while (0)
  77 #define lock_cpu_hotplug_interruptible() 0
  78 #define hotcpu_notifier(fn, pri)
  79
  80 /* CPUs don't go offline once they're online w/o CONFIG_HOTPLUG_CPU */
  81 static inline int cpu_is_offline(int cpu) { return 0; }
  82 #endif
  83
  84 #endif /* _LINUX_CPU_H_ */