cpu.c revision e057d7aea9d8f2a46cd440d8bfb72245d4e72d79 
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, struct sysdev_attribute *attr,
25			   char *buf)
26{
27	struct cpu *cpu = container_of(dev, struct cpu, sysdev);
28
29	return sprintf(buf, "%u\n", !!cpu_online(cpu->sysdev.id));
30}
31
32static ssize_t __ref store_online(struct sys_device *dev, struct sysdev_attribute *attr,
33				 const char *buf, size_t count)
34{
35	struct cpu *cpu = container_of(dev, struct cpu, sysdev);
36	ssize_t ret;
37
38	switch (buf[0]) {
39	case '0':
40		ret = cpu_down(cpu->sysdev.id);
41		if (!ret)
42			kobject_uevent(&dev->kobj, KOBJ_OFFLINE);
43		break;
44	case '1':
45		ret = cpu_up(cpu->sysdev.id);
46		if (!ret)
47			kobject_uevent(&dev->kobj, KOBJ_ONLINE);
48		break;
49	default:
50		ret = -EINVAL;
51	}
52
53	if (ret >= 0)
54		ret = count;
55	return ret;
56}
57static SYSDEV_ATTR(online, 0644, show_online, store_online);
58
59static void __cpuinit register_cpu_control(struct cpu *cpu)
60{
61	sysdev_create_file(&cpu->sysdev, &attr_online);
62}
63void unregister_cpu(struct cpu *cpu)
64{
65	int logical_cpu = cpu->sysdev.id;
66
67	unregister_cpu_under_node(logical_cpu, cpu_to_node(logical_cpu));
68
69	sysdev_remove_file(&cpu->sysdev, &attr_online);
70
71	sysdev_unregister(&cpu->sysdev);
72	per_cpu(cpu_sys_devices, logical_cpu) = NULL;
73	return;
74}
75#else /* ... !CONFIG_HOTPLUG_CPU */
76static inline void register_cpu_control(struct cpu *cpu)
77{
78}
79#endif /* CONFIG_HOTPLUG_CPU */
80
81#ifdef CONFIG_KEXEC
82#include <linux/kexec.h>
83
84static ssize_t show_crash_notes(struct sys_device *dev, struct sysdev_attribute *attr,
85				char *buf)
86{
87	struct cpu *cpu = container_of(dev, struct cpu, sysdev);
88	ssize_t rc;
89	unsigned long long addr;
90	int cpunum;
91
92	cpunum = cpu->sysdev.id;
93
94	/*
95	 * Might be reading other cpu's data based on which cpu read thread
96	 * has been scheduled. But cpu data (memory) is allocated once during
97	 * boot up and this data does not change there after. Hence this
98	 * operation should be safe. No locking required.
99	 */
100	addr = __pa(per_cpu_ptr(crash_notes, cpunum));
101	rc = sprintf(buf, "%Lx\n", addr);
102	return rc;
103}
104static SYSDEV_ATTR(crash_notes, 0400, show_crash_notes, NULL);
105#endif
106
107/*
108 * Print cpu online, possible, present, and system maps
109 */
110static ssize_t print_cpus_map(char *buf, cpumask_t *map)
111{
112	int n = cpulist_scnprintf(buf, PAGE_SIZE-2, map);
113
114	buf[n++] = '\n';
115	buf[n] = '\0';
116	return n;
117}
118
119#define	print_cpus_func(type) \
120static ssize_t print_cpus_##type(struct sysdev_class *class, char *buf)	\
121{									\
122	return print_cpus_map(buf, &cpu_##type##_map);			\
123}									\
124static struct sysdev_class_attribute attr_##type##_map = 		\
125	_SYSDEV_CLASS_ATTR(type, 0444, print_cpus_##type, NULL)
126
127print_cpus_func(online);
128print_cpus_func(possible);
129print_cpus_func(present);
130
131/*
132 * Print values for NR_CPUS and offlined cpus
133 */
134static ssize_t print_cpus_kernel_max(struct sysdev_class *class, char *buf)
135{
136	int n = snprintf(buf, PAGE_SIZE-2, "%d\n", CONFIG_NR_CPUS - 1);
137	return n;
138}
139static SYSDEV_CLASS_ATTR(kernel_max, 0444, print_cpus_kernel_max, NULL);
140
141/* arch-optional setting to enable display of offline cpus >= nr_cpu_ids */
142unsigned int total_cpus;
143
144static ssize_t print_cpus_offline(struct sysdev_class *class, char *buf)
145{
146	int n = 0, len = PAGE_SIZE-2;
147	cpumask_var_t offline;
148
149	/* display offline cpus < nr_cpu_ids */
150	if (!alloc_cpumask_var(&offline, GFP_KERNEL))
151		return -ENOMEM;
152	cpumask_complement(offline, cpu_online_mask);
153	n = cpulist_scnprintf(buf, len, offline);
154	free_cpumask_var(offline);
155
156	/* display offline cpus >= nr_cpu_ids */
157	if (total_cpus && nr_cpu_ids < total_cpus) {
158		if (n && n < len)
159			buf[n++] = ',';
160
161		if (nr_cpu_ids == total_cpus-1)
162			n += snprintf(&buf[n], len - n, "%d", nr_cpu_ids);
163		else
164			n += snprintf(&buf[n], len - n, "%d-%d",
165						      nr_cpu_ids, total_cpus-1);
166	}
167
168	n += snprintf(&buf[n], len - n, "\n");
169	return n;
170}
171static SYSDEV_CLASS_ATTR(offline, 0444, print_cpus_offline, NULL);
172
173static struct sysdev_class_attribute *cpu_state_attr[] = {
174	&attr_online_map,
175	&attr_possible_map,
176	&attr_present_map,
177	&attr_kernel_max,
178	&attr_offline,
179};
180
181static int cpu_states_init(void)
182{
183	int i;
184	int err = 0;
185
186	for (i = 0;  i < ARRAY_SIZE(cpu_state_attr); i++) {
187		int ret;
188		ret = sysdev_class_create_file(&cpu_sysdev_class,
189						cpu_state_attr[i]);
190		if (!err)
191			err = ret;
192	}
193	return err;
194}
195
196/*
197 * register_cpu - Setup a sysfs device for a CPU.
198 * @cpu - cpu->hotpluggable field set to 1 will generate a control file in
199 *	  sysfs for this CPU.
200 * @num - CPU number to use when creating the device.
201 *
202 * Initialize and register the CPU device.
203 */
204int __cpuinit register_cpu(struct cpu *cpu, int num)
205{
206	int error;
207	cpu->node_id = cpu_to_node(num);
208	cpu->sysdev.id = num;
209	cpu->sysdev.cls = &cpu_sysdev_class;
210
211	error = sysdev_register(&cpu->sysdev);
212
213	if (!error && cpu->hotpluggable)
214		register_cpu_control(cpu);
215	if (!error)
216		per_cpu(cpu_sys_devices, num) = &cpu->sysdev;
217	if (!error)
218		register_cpu_under_node(num, cpu_to_node(num));
219
220#ifdef CONFIG_KEXEC
221	if (!error)
222		error = sysdev_create_file(&cpu->sysdev, &attr_crash_notes);
223#endif
224	return error;
225}
226
227struct sys_device *get_cpu_sysdev(unsigned cpu)
228{
229	if (cpu < nr_cpu_ids && cpu_possible(cpu))
230		return per_cpu(cpu_sys_devices, cpu);
231	else
232		return NULL;
233}
234EXPORT_SYMBOL_GPL(get_cpu_sysdev);
235
236int __init cpu_dev_init(void)
237{
238	int err;
239
240	err = sysdev_class_register(&cpu_sysdev_class);
241	if (!err)
242		err = cpu_states_init();
243
244#if defined(CONFIG_SCHED_MC) || defined(CONFIG_SCHED_SMT)
245	if (!err)
246		err = sched_create_sysfs_power_savings_entries(&cpu_sysdev_class);
247#endif
248
249	return err;
250}
251