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/cpu.h>
9#include <linux/topology.h>
10#include <linux/device.h>
11
12#include "base.h"
13
14struct sysdev_class cpu_sysdev_class = {
15 set_kset_name("cpu"),
16};
17EXPORT_SYMBOL(cpu_sysdev_class);
18
19static struct sys_device *cpu_sys_devices[NR_CPUS];
20
21#ifdef CONFIG_HOTPLUG_CPU
22static ssize_t show_online(struct sys_device *dev, char *buf)
23{
24 struct cpu *cpu = container_of(dev, struct cpu, sysdev);
25
26 return sprintf(buf, "%u\n", !!cpu_online(cpu->sysdev.id));
27}
28
29static ssize_t store_online(struct sys_device *dev, const char *buf,
30 size_t count)
31{
32 struct cpu *cpu = container_of(dev, struct cpu, sysdev);
33 ssize_t ret;
34
35 switch (buf[0]) {
36 case '0':
37 ret = cpu_down(cpu->sysdev.id);
38 if (!ret)
39 kobject_uevent(&dev->kobj, KOBJ_OFFLINE);
40 break;
41 case '1':
42 ret = cpu_up(cpu->sysdev.id);
43 if (!ret)
44 kobject_uevent(&dev->kobj, KOBJ_ONLINE);
45 break;
46 default:
47 ret = -EINVAL;
48 }
49
50 if (ret >= 0)
51 ret = count;
52 return ret;
53}
54static SYSDEV_ATTR(online, 0600, show_online, store_online);
55
56static void __devinit register_cpu_control(struct cpu *cpu)
57{
58 sysdev_create_file(&cpu->sysdev, &attr_online);
59}
60void unregister_cpu(struct cpu *cpu, struct node *root)
61{
62 int logical_cpu = cpu->sysdev.id;
63
64 if (root)
65 sysfs_remove_link(&root->sysdev.kobj,
66 kobject_name(&cpu->sysdev.kobj));
67 sysdev_remove_file(&cpu->sysdev, &attr_online);
68
69 sysdev_unregister(&cpu->sysdev);
70 cpu_sys_devices[logical_cpu] = NULL;
71 return;
72}
73#else /* ... !CONFIG_HOTPLUG_CPU */
74static inline void register_cpu_control(struct cpu *cpu)
75{
76}
77#endif /* CONFIG_HOTPLUG_CPU */
78
79#ifdef CONFIG_KEXEC
80#include <linux/kexec.h>
81
82static ssize_t show_crash_notes(struct sys_device *dev, char *buf)
83{
84 struct cpu *cpu = container_of(dev, struct cpu, sysdev);
85 ssize_t rc;
86 unsigned long long addr;
87 int cpunum;
88
89 cpunum = cpu->sysdev.id;
90
91 /*
92 * Might be reading other cpu's data based on which cpu read thread
93 * has been scheduled. But cpu data (memory) is allocated once during
94 * boot up and this data does not change there after. Hence this
95 * operation should be safe. No locking required.
96 */
97 addr = __pa(per_cpu_ptr(crash_notes, cpunum));
98 rc = sprintf(buf, "%Lx\n", addr);
99 return rc;
100}
101static SYSDEV_ATTR(crash_notes, 0400, show_crash_notes, NULL);
102#endif
103
104/*
105 * register_cpu - Setup a driverfs device for a CPU.
106 * @cpu - Callers can set the cpu->no_control field to 1, to indicate not to
107 * generate a control file in sysfs for this CPU.
108 * @num - CPU number to use when creating the device.
109 *
110 * Initialize and register the CPU device.
111 */
112int __devinit register_cpu(struct cpu *cpu, int num, struct node *root)
113{
114 int error;
115
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 if (!error && root)
122 error = sysfs_create_link(&root->sysdev.kobj,
123 &cpu->sysdev.kobj,
124 kobject_name(&cpu->sysdev.kobj));
125 if (!error && !cpu->no_control)
126 register_cpu_control(cpu);
127 if (!error)
128 cpu_sys_devices[num] = &cpu->sysdev;
129
130#ifdef CONFIG_KEXEC
131 if (!error)
132 error = sysdev_create_file(&cpu->sysdev, &attr_crash_notes);
133#endif
134 return error;
135}
136
137struct sys_device *get_cpu_sysdev(unsigned cpu)
138{
139 if (cpu < NR_CPUS)
140 return cpu_sys_devices[cpu];
141 else
142 return NULL;
143}
144EXPORT_SYMBOL_GPL(get_cpu_sysdev);
145
146int __init cpu_dev_init(void)
147{
148 return sysdev_class_register(&cpu_sysdev_class);
149}