cpu.c revision af5ca3f4ec5cc4432a42a73b050dd8898ce8fd00 
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/sched.h>
9#include <linux/cpu.h>
10#include <linux/topology.h>
11#include <linux/device.h>
12#include <linux/node.h>
13
14#include "base.h"
15
16struct sysdev_class cpu_sysdev_class = {
17	.name = "cpu",
18};
19EXPORT_SYMBOL(cpu_sysdev_class);
20
21static struct sys_device *cpu_sys_devices[NR_CPUS];
22
23#ifdef CONFIG_HOTPLUG_CPU
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_uevent(&dev->kobj, KOBJ_OFFLINE);
42		break;
43	case '1':
44		ret = cpu_up(cpu->sysdev.id);
45		if (!ret)
46			kobject_uevent(&dev->kobj, KOBJ_ONLINE);
47		break;
48	default:
49		ret = -EINVAL;
50	}
51
52	if (ret >= 0)
53		ret = count;
54	return ret;
55}
56static SYSDEV_ATTR(online, 0644, 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)
63{
64	int logical_cpu = cpu->sysdev.id;
65
66	unregister_cpu_under_node(logical_cpu, cpu_to_node(logical_cpu));
67
68	sysdev_remove_file(&cpu->sysdev, &attr_online);
69
70	sysdev_unregister(&cpu->sysdev);
71	cpu_sys_devices[logical_cpu] = NULL;
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#ifdef CONFIG_KEXEC
81#include <linux/kexec.h>
82
83static ssize_t show_crash_notes(struct sys_device *dev, char *buf)
84{
85	struct cpu *cpu = container_of(dev, struct cpu, sysdev);
86	ssize_t rc;
87	unsigned long long addr;
88	int cpunum;
89
90	cpunum = cpu->sysdev.id;
91
92	/*
93	 * Might be reading other cpu's data based on which cpu read thread
94	 * has been scheduled. But cpu data (memory) is allocated once during
95	 * boot up and this data does not change there after. Hence this
96	 * operation should be safe. No locking required.
97	 */
98	addr = __pa(per_cpu_ptr(crash_notes, cpunum));
99	rc = sprintf(buf, "%Lx\n", addr);
100	return rc;
101}
102static SYSDEV_ATTR(crash_notes, 0400, show_crash_notes, NULL);
103#endif
104
105/*
106 * register_cpu - Setup a sysfs device for a CPU.
107 * @cpu - cpu->hotpluggable field set to 1 will generate a control file in
108 *	  sysfs for this CPU.
109 * @num - CPU number to use when creating the device.
110 *
111 * Initialize and register the CPU device.
112 */
113int __devinit register_cpu(struct cpu *cpu, int num)
114{
115	int error;
116	cpu->node_id = cpu_to_node(num);
117	cpu->sysdev.id = num;
118	cpu->sysdev.cls = &cpu_sysdev_class;
119
120	error = sysdev_register(&cpu->sysdev);
121
122	if (!error && cpu->hotpluggable)
123		register_cpu_control(cpu);
124	if (!error)
125		cpu_sys_devices[num] = &cpu->sysdev;
126	if (!error)
127		register_cpu_under_node(num, cpu_to_node(num));
128
129#ifdef CONFIG_KEXEC
130	if (!error)
131		error = sysdev_create_file(&cpu->sysdev, &attr_crash_notes);
132#endif
133	return error;
134}
135
136struct sys_device *get_cpu_sysdev(unsigned cpu)
137{
138	if (cpu < NR_CPUS)
139		return cpu_sys_devices[cpu];
140	else
141		return NULL;
142}
143EXPORT_SYMBOL_GPL(get_cpu_sysdev);
144
145int __init cpu_dev_init(void)
146{
147	int err;
148
149	err = sysdev_class_register(&cpu_sysdev_class);
150#if defined(CONFIG_SCHED_MC) || defined(CONFIG_SCHED_SMT)
151	if (!err)
152		err = sched_create_sysfs_power_savings_entries(&cpu_sysdev_class);
153#endif
154
155	return err;
156}
157