cpu.c revision 51be5606d9ff9eb27ed6514f6172fbd7578a25d6 
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_uevent(&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_uevent(&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#ifdef CONFIG_KEXEC
87#include <linux/kexec.h>
88
89static ssize_t show_crash_notes(struct sys_device *dev, char *buf)
90{
91	struct cpu *cpu = container_of(dev, struct cpu, sysdev);
92	ssize_t rc;
93	unsigned long long addr;
94	int cpunum;
95
96	cpunum = cpu->sysdev.id;
97
98	/*
99	 * Might be reading other cpu's data based on which cpu read thread
100	 * has been scheduled. But cpu data (memory) is allocated once during
101	 * boot up and this data does not change there after. Hence this
102	 * operation should be safe. No locking required.
103	 */
104	get_cpu();
105	addr = __pa(per_cpu_ptr(crash_notes, cpunum));
106	rc = sprintf(buf, "%Lx\n", addr);
107	put_cpu();
108	return rc;
109}
110static SYSDEV_ATTR(crash_notes, 0400, show_crash_notes, NULL);
111#endif
112
113/*
114 * register_cpu - Setup a driverfs device for a CPU.
115 * @cpu - Callers can set the cpu->no_control field to 1, to indicate not to
116 *		  generate a control file in sysfs for this CPU.
117 * @num - CPU number to use when creating the device.
118 *
119 * Initialize and register the CPU device.
120 */
121int __devinit register_cpu(struct cpu *cpu, int num, struct node *root)
122{
123	int error;
124
125	cpu->node_id = cpu_to_node(num);
126	cpu->sysdev.id = num;
127	cpu->sysdev.cls = &cpu_sysdev_class;
128
129	error = sysdev_register(&cpu->sysdev);
130	if (!error && root)
131		error = sysfs_create_link(&root->sysdev.kobj,
132					  &cpu->sysdev.kobj,
133					  kobject_name(&cpu->sysdev.kobj));
134	if (!error && !cpu->no_control)
135		register_cpu_control(cpu);
136	if (!error)
137		cpu_sys_devices[num] = &cpu->sysdev;
138
139#ifdef CONFIG_KEXEC
140	if (!error)
141		error = sysdev_create_file(&cpu->sysdev, &attr_crash_notes);
142#endif
143	return error;
144}
145
146struct sys_device *get_cpu_sysdev(int cpu)
147{
148	if (cpu < NR_CPUS)
149		return cpu_sys_devices[cpu];
150	else
151		return NULL;
152}
153EXPORT_SYMBOL_GPL(get_cpu_sysdev);
154
155int __init cpu_dev_init(void)
156{
157	return sysdev_class_register(&cpu_sysdev_class);
158}
159