cpu.c revision fb69c3907ead36b9e9f41ea6f0d0e0ae10a38a47 
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
13struct sysdev_class cpu_sysdev_class = {
14	set_kset_name("cpu"),
15};
16EXPORT_SYMBOL(cpu_sysdev_class);
17
18#ifdef CONFIG_HOTPLUG_CPU
19int __attribute__((weak)) smp_prepare_cpu (int cpu)
20{
21	return 0;
22}
23
24static ssize_t show_online(struct sys_device *dev, char *buf)
25{
26	struct cpu *cpu = container_of(dev, struct cpu, sysdev);
27
28	return sprintf(buf, "%u\n", !!cpu_online(cpu->sysdev.id));
29}
30
31static ssize_t store_online(struct sys_device *dev, const char *buf,
32			    size_t count)
33{
34	struct cpu *cpu = container_of(dev, struct cpu, sysdev);
35	ssize_t ret;
36
37	switch (buf[0]) {
38	case '0':
39		ret = cpu_down(cpu->sysdev.id);
40		if (!ret)
41			kobject_hotplug(&dev->kobj, KOBJ_OFFLINE);
42		break;
43	case '1':
44		ret = smp_prepare_cpu(cpu->sysdev.id);
45		if (!ret)
46			ret = cpu_up(cpu->sysdev.id);
47		if (!ret)
48			kobject_hotplug(&dev->kobj, KOBJ_ONLINE);
49		break;
50	default:
51		ret = -EINVAL;
52	}
53
54	if (ret >= 0)
55		ret = count;
56	return ret;
57}
58static SYSDEV_ATTR(online, 0600, show_online, store_online);
59
60static void __devinit register_cpu_control(struct cpu *cpu)
61{
62	sysdev_create_file(&cpu->sysdev, &attr_online);
63}
64void unregister_cpu(struct cpu *cpu, struct node *root)
65{
66
67	if (root)
68		sysfs_remove_link(&root->sysdev.kobj,
69				  kobject_name(&cpu->sysdev.kobj));
70	sysdev_remove_file(&cpu->sysdev, &attr_online);
71
72	sysdev_unregister(&cpu->sysdev);
73
74	return;
75}
76#else /* ... !CONFIG_HOTPLUG_CPU */
77static inline void register_cpu_control(struct cpu *cpu)
78{
79}
80#endif /* CONFIG_HOTPLUG_CPU */
81
82/*
83 * register_cpu - Setup a driverfs device for a CPU.
84 * @cpu - Callers can set the cpu->no_control field to 1, to indicate not to
85 *		  generate a control file in sysfs for this CPU.
86 * @num - CPU number to use when creating the device.
87 *
88 * Initialize and register the CPU device.
89 */
90int __devinit register_cpu(struct cpu *cpu, int num, struct node *root)
91{
92	int error;
93
94	cpu->node_id = cpu_to_node(num);
95	cpu->sysdev.id = num;
96	cpu->sysdev.cls = &cpu_sysdev_class;
97
98	error = sysdev_register(&cpu->sysdev);
99	if (!error && root)
100		error = sysfs_create_link(&root->sysdev.kobj,
101					  &cpu->sysdev.kobj,
102					  kobject_name(&cpu->sysdev.kobj));
103	if (!error && !cpu->no_control)
104		register_cpu_control(cpu);
105	return error;
106}
107
108
109
110int __init cpu_dev_init(void)
111{
112	return sysdev_class_register(&cpu_sysdev_class);
113}
114