2 * include/linux/cpu.h - generic cpu definition
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.
8 * Basic handling of the devices is done in drivers/base/cpu.c
9 * and system devices are handled in drivers/base/sys.c.
11 * CPUs are exported via sysfs in the class/cpu/devices/
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
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>
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;
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 *);
39 struct notifier_block;
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);
46 int cpu_up(unsigned int cpu);
50 static inline int register_cpu_notifier(struct notifier_block *nb)
54 static inline void unregister_cpu_notifier(struct notifier_block *nb)
58 #endif /* CONFIG_SMP */
59 extern struct sysdev_class cpu_sysdev_class;
61 #ifdef CONFIG_HOTPLUG_CPU
62 /* Stop CPUs going up and down. */
63 extern struct semaphore cpucontrol;
64 #define lock_cpu_hotplug() down(&cpucontrol)
65 #define unlock_cpu_hotplug() up(&cpucontrol)
66 #define lock_cpu_hotplug_interruptible() down_interruptible(&cpucontrol)
67 #define hotcpu_notifier(fn, pri) { \
68 static struct notifier_block fn##_nb = \
69 { .notifier_call = fn, .priority = pri }; \
70 register_cpu_notifier(&fn##_nb); \
72 int cpu_down(unsigned int cpu);
73 extern int __attribute__((weak)) smp_prepare_cpu(int cpu);
74 #define cpu_is_offline(cpu) unlikely(!cpu_online(cpu))
76 #define lock_cpu_hotplug() do { } while (0)
77 #define unlock_cpu_hotplug() do { } while (0)
78 #define lock_cpu_hotplug_interruptible() 0
79 #define hotcpu_notifier(fn, pri)
81 /* CPUs don't go offline once they're online w/o CONFIG_HOTPLUG_CPU */
82 static inline int cpu_is_offline(int cpu) { return 0; }
85 #endif /* _LINUX_CPU_H_ */