xref: /openbmc/linux/drivers/base/cpu.c (revision d5cb9783536a41df9f9cba5b0a1d78047ed787f7)
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 
14 struct sysdev_class cpu_sysdev_class = {
15 	set_kset_name("cpu"),
16 };
17 EXPORT_SYMBOL(cpu_sysdev_class);
18 
19 static struct sys_device *cpu_sys_devices[NR_CPUS];
20 
21 #ifdef CONFIG_HOTPLUG_CPU
22 int __attribute__((weak)) smp_prepare_cpu (int cpu)
23 {
24 	return 0;
25 }
26 
27 static 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 
34 static 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_hotplug(&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_hotplug(&dev->kobj, KOBJ_ONLINE);
52 		break;
53 	default:
54 		ret = -EINVAL;
55 	}
56 
57 	if (ret >= 0)
58 		ret = count;
59 	return ret;
60 }
61 static SYSDEV_ATTR(online, 0600, show_online, store_online);
62 
63 static void __devinit register_cpu_control(struct cpu *cpu)
64 {
65 	sysdev_create_file(&cpu->sysdev, &attr_online);
66 }
67 void 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 */
81 static inline void register_cpu_control(struct cpu *cpu)
82 {
83 }
84 #endif /* CONFIG_HOTPLUG_CPU */
85 
86 /*
87  * register_cpu - Setup a driverfs device for a CPU.
88  * @cpu - Callers can set the cpu->no_control field to 1, to indicate not to
89  *		  generate a control file in sysfs for this CPU.
90  * @num - CPU number to use when creating the device.
91  *
92  * Initialize and register the CPU device.
93  */
94 int __devinit register_cpu(struct cpu *cpu, int num, struct node *root)
95 {
96 	int error;
97 
98 	cpu->node_id = cpu_to_node(num);
99 	cpu->sysdev.id = num;
100 	cpu->sysdev.cls = &cpu_sysdev_class;
101 
102 	error = sysdev_register(&cpu->sysdev);
103 	if (!error && root)
104 		error = sysfs_create_link(&root->sysdev.kobj,
105 					  &cpu->sysdev.kobj,
106 					  kobject_name(&cpu->sysdev.kobj));
107 	if (!error && !cpu->no_control)
108 		register_cpu_control(cpu);
109 	if (!error)
110 		cpu_sys_devices[num] = &cpu->sysdev;
111 	return error;
112 }
113 
114 struct sys_device *get_cpu_sysdev(int cpu)
115 {
116 	if (cpu < NR_CPUS)
117 		return cpu_sys_devices[cpu];
118 	else
119 		return NULL;
120 }
121 EXPORT_SYMBOL_GPL(get_cpu_sysdev);
122 
123 int __init cpu_dev_init(void)
124 {
125 	return sysdev_class_register(&cpu_sysdev_class);
126 }
127