cpu.c revision 143aa5c53bd3895d42d7c08753fe58293988a69d 
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 DEFINE_PER_CPU(struct sys_device *, cpu_sys_devices);
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 __ref 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 __cpuinit 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	per_cpu(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 * Print cpu online, possible, present, and system maps
107 */
108static ssize_t print_cpus_map(char *buf, cpumask_t *map)
109{
110	int n = cpulist_scnprintf(buf, PAGE_SIZE-2, *map);
111
112	buf[n++] = '\n';
113	buf[n] = '\0';
114	return n;
115}
116
117#define	print_cpus_func(type) \
118static ssize_t print_cpus_##type(struct sysdev_class *class, char *buf)	\
119{									\
120	return print_cpus_map(buf, &cpu_##type##_map);			\
121}									\
122static struct sysdev_class_attribute attr_##type##_map = 		\
123	_SYSDEV_CLASS_ATTR(type, 0444, print_cpus_##type, NULL)
124
125print_cpus_func(online);
126print_cpus_func(possible);
127print_cpus_func(present);
128
129static struct sysdev_class_attribute *cpu_state_attr[] = {
130	&attr_online_map,
131	&attr_possible_map,
132	&attr_present_map,
133};
134
135static int cpu_states_init(void)
136{
137	int i;
138	int err = 0;
139
140	for (i = 0;  i < ARRAY_SIZE(cpu_state_attr); i++) {
141		int ret;
142		ret = sysdev_class_create_file(&cpu_sysdev_class,
143						cpu_state_attr[i]);
144		if (!err)
145			err = ret;
146	}
147	return err;
148}
149
150/*
151 * register_cpu - Setup a sysfs device for a CPU.
152 * @cpu - cpu->hotpluggable field set to 1 will generate a control file in
153 *	  sysfs for this CPU.
154 * @num - CPU number to use when creating the device.
155 *
156 * Initialize and register the CPU device.
157 */
158int __cpuinit register_cpu(struct cpu *cpu, int num)
159{
160	int error;
161	cpu->node_id = cpu_to_node(num);
162	cpu->sysdev.id = num;
163	cpu->sysdev.cls = &cpu_sysdev_class;
164
165	error = sysdev_register(&cpu->sysdev);
166
167	if (!error && cpu->hotpluggable)
168		register_cpu_control(cpu);
169	if (!error)
170		per_cpu(cpu_sys_devices, num) = &cpu->sysdev;
171	if (!error)
172		register_cpu_under_node(num, cpu_to_node(num));
173
174#ifdef CONFIG_KEXEC
175	if (!error)
176		error = sysdev_create_file(&cpu->sysdev, &attr_crash_notes);
177#endif
178	return error;
179}
180
181struct sys_device *get_cpu_sysdev(unsigned cpu)
182{
183	if (cpu < nr_cpu_ids && cpu_possible(cpu))
184		return per_cpu(cpu_sys_devices, cpu);
185	else
186		return NULL;
187}
188EXPORT_SYMBOL_GPL(get_cpu_sysdev);
189
190int __init cpu_dev_init(void)
191{
192	int err;
193
194	err = sysdev_class_register(&cpu_sysdev_class);
195	if (!err)
196		err = cpu_states_init();
197
198#if defined(CONFIG_SCHED_MC) || defined(CONFIG_SCHED_SMT)
199	if (!err)
200		err = sched_create_sysfs_power_savings_entries(&cpu_sysdev_class);
201#endif
202
203	return err;
204}
205