cpu.c revision ad74557a49d1dea428fb0ad60e75a5aa37610e1d 
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
19static struct sys_device *cpu_sys_devices[NR_CPUS];
20
21#ifdef CONFIG_HOTPLUG_CPU
22int __attribute__((weak)) smp_prepare_cpu (int cpu)
23{
24	return 0;
25}
26
27static ssize_t show_online(struct sys_device *dev, char *buf)
28{
29	struct cpu *cpu = container_of(dev, struct cpu, sysdev);
30
31	return sprintf(buf, "%u\n", !!cpu_online(cpu->sysdev.id));
32}
33
34static ssize_t store_online(struct sys_device *dev, const char *buf,
35			    size_t count)
36{
37	struct cpu *cpu = container_of(dev, struct cpu, sysdev);
38	ssize_t ret;
39
40	switch (buf[0]) {
41	case '0':
42		ret = cpu_down(cpu->sysdev.id);
43		if (!ret)
44			kobject_hotplug(&dev->kobj, KOBJ_OFFLINE);
45		break;
46	case '1':
47		ret = smp_prepare_cpu(cpu->sysdev.id);
48		if (!ret)
49			ret = cpu_up(cpu->sysdev.id);
50		if (!ret)
51			kobject_hotplug(&dev->kobj, KOBJ_ONLINE);
52		break;
53	default:
54		ret = -EINVAL;
55	}
56
57	if (ret >= 0)
58		ret = count;
59	return ret;
60}
61static SYSDEV_ATTR(online, 0600, show_online, store_online);
62
63static void __devinit register_cpu_control(struct cpu *cpu)
64{
65	sysdev_create_file(&cpu->sysdev, &attr_online);
66}
67void unregister_cpu(struct cpu *cpu, struct node *root)
68{
69	int logical_cpu = cpu->sysdev.id;
70
71	if (root)
72		sysfs_remove_link(&root->sysdev.kobj,
73				  kobject_name(&cpu->sysdev.kobj));
74	sysdev_remove_file(&cpu->sysdev, &attr_online);
75
76	sysdev_unregister(&cpu->sysdev);
77	cpu_sys_devices[logical_cpu] = NULL;
78	return;
79}
80#else /* ... !CONFIG_HOTPLUG_CPU */
81static inline void register_cpu_control(struct cpu *cpu)
82{
83}
84#endif /* CONFIG_HOTPLUG_CPU */
85
86/*
87 * register_cpu - Setup a driverfs device for a CPU.
88 * @cpu - Callers can set the cpu->no_control field to 1, to indicate not to
89 *		  generate a control file in sysfs for this CPU.
90 * @num - CPU number to use when creating the device.
91 *
92 * Initialize and register the CPU device.
93 */
94int __devinit register_cpu(struct cpu *cpu, int num, struct node *root)
95{
96	int error;
97
98	cpu->node_id = cpu_to_node(num);
99	cpu->sysdev.id = num;
100	cpu->sysdev.cls = &cpu_sysdev_class;
101
102	error = sysdev_register(&cpu->sysdev);
103	if (!error && root)
104		error = sysfs_create_link(&root->sysdev.kobj,
105					  &cpu->sysdev.kobj,
106					  kobject_name(&cpu->sysdev.kobj));
107	if (!error && !cpu->no_control)
108		register_cpu_control(cpu);
109	if (!error)
110		cpu_sys_devices[num] = &cpu->sysdev;
111	return error;
112}
113
114struct sys_device *get_cpu_sysdev(int cpu)
115{
116	if (cpu < NR_CPUS)
117		return cpu_sys_devices[cpu];
118	else
119		return NULL;
120}
121EXPORT_SYMBOL_GPL(get_cpu_sysdev);
122
123int __init cpu_dev_init(void)
124{
125	return sysdev_class_register(&cpu_sysdev_class);
126}
127