cpu.c revision 67fc233f4fb67907861b4077cea5294035f80dc7 
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
16static struct sysdev_class_attribute *cpu_sysdev_class_attrs[];
17
18struct sysdev_class cpu_sysdev_class = {
19	.name = "cpu",
20	.attrs = cpu_sysdev_class_attrs,
21};
22EXPORT_SYMBOL(cpu_sysdev_class);
23
24static DEFINE_PER_CPU(struct sys_device *, cpu_sys_devices);
25
26#ifdef CONFIG_HOTPLUG_CPU
27static ssize_t show_online(struct sys_device *dev, struct sysdev_attribute *attr,
28			   char *buf)
29{
30	struct cpu *cpu = container_of(dev, struct cpu, sysdev);
31
32	return sprintf(buf, "%u\n", !!cpu_online(cpu->sysdev.id));
33}
34
35static ssize_t __ref store_online(struct sys_device *dev, struct sysdev_attribute *attr,
36				 const char *buf, size_t count)
37{
38	struct cpu *cpu = container_of(dev, struct cpu, sysdev);
39	ssize_t ret;
40
41	cpu_hotplug_driver_lock();
42	switch (buf[0]) {
43	case '0':
44		ret = cpu_down(cpu->sysdev.id);
45		if (!ret)
46			kobject_uevent(&dev->kobj, KOBJ_OFFLINE);
47		break;
48	case '1':
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	cpu_hotplug_driver_unlock();
57
58	if (ret >= 0)
59		ret = count;
60	return ret;
61}
62static SYSDEV_ATTR(online, 0644, show_online, store_online);
63
64static void __cpuinit register_cpu_control(struct cpu *cpu)
65{
66	sysdev_create_file(&cpu->sysdev, &attr_online);
67}
68void unregister_cpu(struct cpu *cpu)
69{
70	int logical_cpu = cpu->sysdev.id;
71
72	unregister_cpu_under_node(logical_cpu, cpu_to_node(logical_cpu));
73
74	sysdev_remove_file(&cpu->sysdev, &attr_online);
75
76	sysdev_unregister(&cpu->sysdev);
77	per_cpu(cpu_sys_devices, logical_cpu) = NULL;
78	return;
79}
80
81#ifdef CONFIG_ARCH_CPU_PROBE_RELEASE
82static ssize_t cpu_probe_store(struct sysdev_class *class,
83			       struct sysdev_class_attribute *attr,
84			       const char *buf,
85			       size_t count)
86{
87	return arch_cpu_probe(buf, count);
88}
89
90static ssize_t cpu_release_store(struct sysdev_class *class,
91				 struct sysdev_class_attribute *attr,
92				 const char *buf,
93				 size_t count)
94{
95	return arch_cpu_release(buf, count);
96}
97
98static SYSDEV_CLASS_ATTR(probe, S_IWUSR, NULL, cpu_probe_store);
99static SYSDEV_CLASS_ATTR(release, S_IWUSR, NULL, cpu_release_store);
100#endif /* CONFIG_ARCH_CPU_PROBE_RELEASE */
101
102#else /* ... !CONFIG_HOTPLUG_CPU */
103static inline void register_cpu_control(struct cpu *cpu)
104{
105}
106#endif /* CONFIG_HOTPLUG_CPU */
107
108#ifdef CONFIG_KEXEC
109#include <linux/kexec.h>
110
111static ssize_t show_crash_notes(struct sys_device *dev, struct sysdev_attribute *attr,
112				char *buf)
113{
114	struct cpu *cpu = container_of(dev, struct cpu, sysdev);
115	ssize_t rc;
116	unsigned long long addr;
117	int cpunum;
118
119	cpunum = cpu->sysdev.id;
120
121	/*
122	 * Might be reading other cpu's data based on which cpu read thread
123	 * has been scheduled. But cpu data (memory) is allocated once during
124	 * boot up and this data does not change there after. Hence this
125	 * operation should be safe. No locking required.
126	 */
127	addr = per_cpu_ptr_to_phys(per_cpu_ptr(crash_notes, cpunum));
128	rc = sprintf(buf, "%Lx\n", addr);
129	return rc;
130}
131static SYSDEV_ATTR(crash_notes, 0400, show_crash_notes, NULL);
132#endif
133
134/*
135 * Print cpu online, possible, present, and system maps
136 */
137
138struct cpu_attr {
139	struct sysdev_class_attribute attr;
140	const struct cpumask *const * const map;
141};
142
143static ssize_t show_cpus_attr(struct sysdev_class *class,
144			      struct sysdev_class_attribute *attr,
145			      char *buf)
146{
147	struct cpu_attr *ca = container_of(attr, struct cpu_attr, attr);
148	int n = cpulist_scnprintf(buf, PAGE_SIZE-2, *(ca->map));
149
150	buf[n++] = '\n';
151	buf[n] = '\0';
152	return n;
153}
154
155#define _CPU_ATTR(name, map)						\
156	{ _SYSDEV_CLASS_ATTR(name, 0444, show_cpus_attr, NULL), map }
157
158/* Keep in sync with cpu_sysdev_class_attrs */
159static struct cpu_attr cpu_attrs[] = {
160	_CPU_ATTR(online, &cpu_online_mask),
161	_CPU_ATTR(possible, &cpu_possible_mask),
162	_CPU_ATTR(present, &cpu_present_mask),
163};
164
165/*
166 * Print values for NR_CPUS and offlined cpus
167 */
168static ssize_t print_cpus_kernel_max(struct sysdev_class *class,
169				     struct sysdev_class_attribute *attr, char *buf)
170{
171	int n = snprintf(buf, PAGE_SIZE-2, "%d\n", NR_CPUS - 1);
172	return n;
173}
174static SYSDEV_CLASS_ATTR(kernel_max, 0444, print_cpus_kernel_max, NULL);
175
176/* arch-optional setting to enable display of offline cpus >= nr_cpu_ids */
177unsigned int total_cpus;
178
179static ssize_t print_cpus_offline(struct sysdev_class *class,
180				  struct sysdev_class_attribute *attr, char *buf)
181{
182	int n = 0, len = PAGE_SIZE-2;
183	cpumask_var_t offline;
184
185	/* display offline cpus < nr_cpu_ids */
186	if (!alloc_cpumask_var(&offline, GFP_KERNEL))
187		return -ENOMEM;
188	cpumask_complement(offline, cpu_online_mask);
189	n = cpulist_scnprintf(buf, len, offline);
190	free_cpumask_var(offline);
191
192	/* display offline cpus >= nr_cpu_ids */
193	if (total_cpus && nr_cpu_ids < total_cpus) {
194		if (n && n < len)
195			buf[n++] = ',';
196
197		if (nr_cpu_ids == total_cpus-1)
198			n += snprintf(&buf[n], len - n, "%d", nr_cpu_ids);
199		else
200			n += snprintf(&buf[n], len - n, "%d-%d",
201						      nr_cpu_ids, total_cpus-1);
202	}
203
204	n += snprintf(&buf[n], len - n, "\n");
205	return n;
206}
207static SYSDEV_CLASS_ATTR(offline, 0444, print_cpus_offline, NULL);
208
209/*
210 * register_cpu - Setup a sysfs device for a CPU.
211 * @cpu - cpu->hotpluggable field set to 1 will generate a control file in
212 *	  sysfs for this CPU.
213 * @num - CPU number to use when creating the device.
214 *
215 * Initialize and register the CPU device.
216 */
217int __cpuinit register_cpu(struct cpu *cpu, int num)
218{
219	int error;
220	cpu->node_id = cpu_to_node(num);
221	cpu->sysdev.id = num;
222	cpu->sysdev.cls = &cpu_sysdev_class;
223
224	error = sysdev_register(&cpu->sysdev);
225
226	if (!error && cpu->hotpluggable)
227		register_cpu_control(cpu);
228	if (!error)
229		per_cpu(cpu_sys_devices, num) = &cpu->sysdev;
230	if (!error)
231		register_cpu_under_node(num, cpu_to_node(num));
232
233#ifdef CONFIG_KEXEC
234	if (!error)
235		error = sysdev_create_file(&cpu->sysdev, &attr_crash_notes);
236#endif
237	return error;
238}
239
240struct sys_device *get_cpu_sysdev(unsigned cpu)
241{
242	if (cpu < nr_cpu_ids && cpu_possible(cpu))
243		return per_cpu(cpu_sys_devices, cpu);
244	else
245		return NULL;
246}
247EXPORT_SYMBOL_GPL(get_cpu_sysdev);
248
249int __init cpu_dev_init(void)
250{
251	int err;
252
253	err = sysdev_class_register(&cpu_sysdev_class);
254#if defined(CONFIG_SCHED_MC) || defined(CONFIG_SCHED_SMT)
255	if (!err)
256		err = sched_create_sysfs_power_savings_entries(&cpu_sysdev_class);
257#endif
258
259	return err;
260}
261
262static struct sysdev_class_attribute *cpu_sysdev_class_attrs[] = {
263#ifdef CONFIG_ARCH_CPU_PROBE_RELEASE
264	&attr_probe,
265	&attr_release,
266#endif
267	&cpu_attrs[0].attr,
268	&cpu_attrs[1].attr,
269	&cpu_attrs[2].attr,
270	&attr_kernel_max,
271	&attr_offline,
272	NULL
273};
274