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
22int __attribute__((weak)) smp_prepare_cpu (int cpu)
23{
24 return 0;
25}
26
27static ssize_t show_online(struct sys_device *dev, char *buf)
28{
29 struct cpu *cpu = container_of(dev, struct cpu, sysdev);
30
31 return sprintf(buf, "%u\n", !!cpu_online(cpu->sysdev.id));
32}
33
34static ssize_t store_online(struct sys_device *dev, const char *buf,
35 size_t count)
36{
37 struct cpu *cpu = container_of(dev, struct cpu, sysdev);
38 ssize_t ret;
39
40 switch (buf[0]) {
41 case '0':
42 ret = cpu_down(cpu->sysdev.id);
43 if (!ret)
44 kobject_uevent(&dev->kobj, KOBJ_OFFLINE);
45 break;
46 case '1':
47 ret = smp_prepare_cpu(cpu->sysdev.id);
48 if (!ret)
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
57 if (ret >= 0)
58 ret = count;
59 return ret;
60}
61static SYSDEV_ATTR(online, 0600, show_online, store_online);
62
63static void __devinit register_cpu_control(struct cpu *cpu)
64{
65 sysdev_create_file(&cpu->sysdev, &attr_online);
66}
67void unregister_cpu(struct cpu *cpu, struct node *root)
68{
69 int logical_cpu = cpu->sysdev.id;
70
71 if (root)
72 sysfs_remove_link(&root->sysdev.kobj,
73 kobject_name(&cpu->sysdev.kobj));
74 sysdev_remove_file(&cpu->sysdev, &attr_online);
75
76 sysdev_unregister(&cpu->sysdev);
77 cpu_sys_devices[logical_cpu] = NULL;
78 return;
79}
80#else /* ... !CONFIG_HOTPLUG_CPU */
81static inline void register_cpu_control(struct cpu *cpu)
82{
83}
84#endif /* CONFIG_HOTPLUG_CPU */
85
86#ifdef CONFIG_KEXEC
87#include <linux/kexec.h>
88
89static ssize_t show_crash_notes(struct sys_device *dev, char *buf)
90{
91 struct cpu *cpu = container_of(dev, struct cpu, sysdev);
92 ssize_t rc;
93 unsigned long long addr;
94 int cpunum;
95
96 cpunum = cpu->sysdev.id;
97
98 /*
99 * Might be reading other cpu's data based on which cpu read thread
100 * has been scheduled. But cpu data (memory) is allocated once during
101 * boot up and this data does not change there after. Hence this
102 * operation should be safe. No locking required.
103 */
104 addr = __pa(per_cpu_ptr(crash_notes, cpunum));
105 rc = sprintf(buf, "%Lx\n", addr);
106 return rc;
107}
108static SYSDEV_ATTR(crash_notes, 0400, show_crash_notes, NULL);
109#endif
110
111/*
112 * register_cpu - Setup a driverfs device for a CPU.
113 * @cpu - Callers can set the cpu->no_control field to 1, to indicate not to
114 * generate a control file in sysfs for this CPU.
115 * @num - CPU number to use when creating the device.
116 *
117 * Initialize and register the CPU device.
118 */
119int __devinit register_cpu(struct cpu *cpu, int num, struct node *root)
120{
121 int error;
122
123 cpu->node_id = cpu_to_node(num);
124 cpu->sysdev.id = num;
125 cpu->sysdev.cls = &cpu_sysdev_class;
126
127 error = sysdev_register(&cpu->sysdev);
128 if (!error && root)
129 error = sysfs_create_link(&root->sysdev.kobj,
130 &cpu->sysdev.kobj,
131 kobject_name(&cpu->sysdev.kobj));
132 if (!error && !cpu->no_control)
133 register_cpu_control(cpu);
134 if (!error)
135 cpu_sys_devices[num] = &cpu->sysdev;
136
137#ifdef CONFIG_KEXEC
138 if (!error)
139 error = sysdev_create_file(&cpu->sysdev, &attr_crash_notes);
140#endif
141 return error;
142}
143
144struct sys_device *get_cpu_sysdev(int cpu)
145{
146 if (cpu < NR_CPUS)
147 return cpu_sys_devices[cpu];
148 else
149 return NULL;
150}
151EXPORT_SYMBOL_GPL(get_cpu_sysdev);
152
153int __init cpu_dev_init(void)
154{
155 return sysdev_class_register(&cpu_sysdev_class);
156}