xref: /openbmc/linux/kernel/ksysfs.c (revision d5cb9783536a41df9f9cba5b0a1d78047ed787f7)
1 /*
2  * kernel/ksysfs.c - sysfs attributes in /sys/kernel, which
3  * 		     are not related to any other subsystem
4  *
5  * Copyright (C) 2004 Kay Sievers <kay.sievers@vrfy.org>
6  *
7  * This file is release under the GPLv2
8  *
9  */
10 
11 #include <linux/config.h>
12 #include <linux/kobject.h>
13 #include <linux/string.h>
14 #include <linux/sysfs.h>
15 #include <linux/module.h>
16 #include <linux/init.h>
17 
18 #define KERNEL_ATTR_RO(_name) \
19 static struct subsys_attribute _name##_attr = __ATTR_RO(_name)
20 
21 #define KERNEL_ATTR_RW(_name) \
22 static struct subsys_attribute _name##_attr = \
23 	__ATTR(_name, 0644, _name##_show, _name##_store)
24 
25 #ifdef CONFIG_HOTPLUG
26 static ssize_t hotplug_seqnum_show(struct subsystem *subsys, char *page)
27 {
28 	return sprintf(page, "%llu\n", (unsigned long long)hotplug_seqnum);
29 }
30 KERNEL_ATTR_RO(hotplug_seqnum);
31 #endif
32 
33 #ifdef CONFIG_KEXEC
34 #include <asm/kexec.h>
35 
36 static ssize_t crash_notes_show(struct subsystem *subsys, char *page)
37 {
38 	return sprintf(page, "%p\n", (void *)crash_notes);
39 }
40 KERNEL_ATTR_RO(crash_notes);
41 #endif
42 
43 decl_subsys(kernel, NULL, NULL);
44 EXPORT_SYMBOL_GPL(kernel_subsys);
45 
46 static struct attribute * kernel_attrs[] = {
47 #ifdef CONFIG_HOTPLUG
48 	&hotplug_seqnum_attr.attr,
49 #endif
50 #ifdef CONFIG_KEXEC
51 	&crash_notes_attr.attr,
52 #endif
53 	NULL
54 };
55 
56 static struct attribute_group kernel_attr_group = {
57 	.attrs = kernel_attrs,
58 };
59 
60 static int __init ksysfs_init(void)
61 {
62 	int error = subsystem_register(&kernel_subsys);
63 	if (!error)
64 		error = sysfs_create_group(&kernel_subsys.kset.kobj,
65 					   &kernel_attr_group);
66 
67 	return error;
68 }
69 
70 core_initcall(ksysfs_init);
71