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 extern struct sys_device *get_cpu_sysdev(int cpu);
  36 #ifdef CONFIG_HOTPLUG_CPU
  37 extern void unregister_cpu(struct cpu *, struct node *);
  38 #endif
  39 struct notifier_block;
  40
  41 #ifdef CONFIG_SMP
  42 /* Need to know about CPUs going up/down? */
  43 extern int register_cpu_notifier(struct notifier_block *nb);
  44 extern void unregister_cpu_notifier(struct notifier_block *nb);
  45 extern int current_in_cpu_hotplug(void);
  46
  47 int cpu_up(unsigned int cpu);
  48
  49 #else
  50
  51 static inline int register_cpu_notifier(struct notifier_block *nb)
  52 {
  53         return 0;
  54 }
  55 static inline void unregister_cpu_notifier(struct notifier_block *nb)
  56 {
  57 }
  58 static inline int current_in_cpu_hotplug(void)
  59 {
  60         return 0;
  61 }
  62
  63 #endif /* CONFIG_SMP */
  64 extern struct sysdev_class cpu_sysdev_class;
  65
  66 #ifdef CONFIG_HOTPLUG_CPU
  67 /* Stop CPUs going up and down. */
  68 extern struct semaphore cpucontrol;
  69 #define lock_cpu_hotplug()      down(&cpucontrol)
  70 #define unlock_cpu_hotplug()    up(&cpucontrol)
  71 #define lock_cpu_hotplug_interruptible() down_interruptible(&cpucontrol)
  72 #define hotcpu_notifier(fn, pri) {                              \
  73         static struct notifier_block fn##_nb =                  \
  74                 { .notifier_call = fn, .priority = pri };       \
  75         register_cpu_notifier(&fn##_nb);                        \
  76 }
  77 int cpu_down(unsigned int cpu);
  78 extern int __attribute__((weak)) smp_prepare_cpu(int cpu);
  79 #define cpu_is_offline(cpu) unlikely(!cpu_online(cpu))
  80 #else
  81 #define lock_cpu_hotplug()      do { } while (0)
  82 #define unlock_cpu_hotplug()    do { } while (0)
  83 #define lock_cpu_hotplug_interruptible() 0
  84 #define hotcpu_notifier(fn, pri)
  85
  86 /* CPUs don't go offline once they're online w/o CONFIG_HOTPLUG_CPU */
  87 static inline int cpu_is_offline(int cpu) { return 0; }
  88 #endif
  89
  90 #endif /* _LINUX_CPU_H_ */