kernel/ksysfs.c

   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);