cpu.c revision 52a119feaad92d44a0e97d01b22afbcbaf3fc079 
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		break;
48	default:
49		ret = -EINVAL;
50	}
51
52	if (ret >= 0)
53		ret = count;
54	return ret;
55}
56static SYSDEV_ATTR(online, 0600, show_online, store_online);
57
58static void __devinit register_cpu_control(struct cpu *cpu)
59{
60	sysdev_create_file(&cpu->sysdev, &attr_online);
61}
62void unregister_cpu(struct cpu *cpu, struct node *root)
63{
64
65	if (root)
66		sysfs_remove_link(&root->sysdev.kobj,
67				  kobject_name(&cpu->sysdev.kobj));
68	sysdev_remove_file(&cpu->sysdev, &attr_online);
69
70	sysdev_unregister(&cpu->sysdev);
71
72	return;
73}
74#else /* ... !CONFIG_HOTPLUG_CPU */
75static inline void register_cpu_control(struct cpu *cpu)
76{
77}
78#endif /* CONFIG_HOTPLUG_CPU */
79
80/*
81 * register_cpu - Setup a driverfs device for a CPU.
82 * @cpu - Callers can set the cpu->no_control field to 1, to indicate not to
83 *		  generate a control file in sysfs for this CPU.
84 * @num - CPU number to use when creating the device.
85 *
86 * Initialize and register the CPU device.
87 */
88int __devinit register_cpu(struct cpu *cpu, int num, struct node *root)
89{
90	int error;
91
92	cpu->node_id = cpu_to_node(num);
93	cpu->sysdev.id = num;
94	cpu->sysdev.cls = &cpu_sysdev_class;
95
96	error = sysdev_register(&cpu->sysdev);
97	if (!error && root)
98		error = sysfs_create_link(&root->sysdev.kobj,
99					  &cpu->sysdev.kobj,
100					  kobject_name(&cpu->sysdev.kobj));
101	if (!error && !cpu->no_control)
102		register_cpu_control(cpu);
103	return error;
104}
105
106
107
108int __init cpu_dev_init(void)
109{
110	return sysdev_class_register(&cpu_sysdev_class);
111}
112