cpu.c revision a1bdc7aad8b557176ccecff1da137ebe3090871e 
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
14struct sysdev_class cpu_sysdev_class = {
15	set_kset_name("cpu"),
16};
17EXPORT_SYMBOL(cpu_sysdev_class);
18
19#ifdef CONFIG_HOTPLUG_CPU
20int __attribute__((weak)) smp_prepare_cpu (int cpu)
21{
22	return 0;
23}
24
25static 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
32static 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}
59static SYSDEV_ATTR(online, 0600, show_online, store_online);
60
61static void __devinit register_cpu_control(struct cpu *cpu)
62{
63	sysdev_create_file(&cpu->sysdev, &attr_online);
64}
65void 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 */
78static 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 */
91int __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
111int __init cpu_dev_init(void)
112{
113	return sysdev_class_register(&cpu_sysdev_class);
114}
115