Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
tjh.dev
kernel
os
linux
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
131static struct sysdev_class_attribute *cpu_state_attr[] = {
132 &attr_online_map,
133 &attr_possible_map,
134 &attr_present_map,
135};
136
137static int cpu_states_init(void)
138{
139 int i;
140 int err = 0;
141
142 for (i = 0; i < ARRAY_SIZE(cpu_state_attr); i++) {
143 int ret;
144 ret = sysdev_class_create_file(&cpu_sysdev_class,
145 cpu_state_attr[i]);
146 if (!err)
147 err = ret;
148 }
149 return err;
150}
151
152/*
153 * register_cpu - Setup a sysfs device for a CPU.
154 * @cpu - cpu->hotpluggable field set to 1 will generate a control file in
155 * sysfs for this CPU.
156 * @num - CPU number to use when creating the device.
157 *
158 * Initialize and register the CPU device.
159 */
160int __cpuinit register_cpu(struct cpu *cpu, int num)
161{
162 int error;
163 cpu->node_id = cpu_to_node(num);
164 cpu->sysdev.id = num;
165 cpu->sysdev.cls = &cpu_sysdev_class;
166
167 error = sysdev_register(&cpu->sysdev);
168
169 if (!error && cpu->hotpluggable)
170 register_cpu_control(cpu);
171 if (!error)
172 per_cpu(cpu_sys_devices, num) = &cpu->sysdev;
173 if (!error)
174 register_cpu_under_node(num, cpu_to_node(num));
175
176#ifdef CONFIG_KEXEC
177 if (!error)
178 error = sysdev_create_file(&cpu->sysdev, &attr_crash_notes);
179#endif
180 return error;
181}
182
183struct sys_device *get_cpu_sysdev(unsigned cpu)
184{
185 if (cpu < nr_cpu_ids && cpu_possible(cpu))
186 return per_cpu(cpu_sys_devices, cpu);
187 else
188 return NULL;
189}
190EXPORT_SYMBOL_GPL(get_cpu_sysdev);
191
192int __init cpu_dev_init(void)
193{
194 int err;
195
196 err = sysdev_class_register(&cpu_sysdev_class);
197 if (!err)
198 err = cpu_states_init();
199
200#if defined(CONFIG_SCHED_MC) || defined(CONFIG_SCHED_SMT)
201 if (!err)
202 err = sched_create_sysfs_power_savings_entries(&cpu_sysdev_class);
203#endif
204
205 return err;
206}