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 u64 uevent_seqnum;
  19 char uevent_helper[UEVENT_HELPER_PATH_LEN] = "/sbin/hotplug";
  20
  21 #define KERNEL_ATTR_RO(_name) \
  22 static struct subsys_attribute _name##_attr = __ATTR_RO(_name)
  23
  24 #define KERNEL_ATTR_RW(_name) \
  25 static struct subsys_attribute _name##_attr = \
  26         __ATTR(_name, 0644, _name##_show, _name##_store)
  27
  28 #ifdef CONFIG_HOTPLUG
  29 /* current uevent sequence number */
  30 static ssize_t uevent_seqnum_show(struct subsystem *subsys, char *page)
  31 {
  32         return sprintf(page, "%llu\n", (unsigned long long)uevent_seqnum);
  33 }
  34 KERNEL_ATTR_RO(uevent_seqnum);
  35
  36 /* uevent helper program, used during early boo */
  37 static ssize_t uevent_helper_show(struct subsystem *subsys, char *page)
  38 {
  39         return sprintf(page, "%s\n", uevent_helper);
  40 }
  41 static ssize_t uevent_helper_store(struct subsystem *subsys, const char *page, size_t count)
  42 {
  43         if (count+1 > UEVENT_HELPER_PATH_LEN)
  44                 return -ENOENT;
  45         memcpy(uevent_helper, page, count);
  46         uevent_helper[count] = '\0';
  47         if (count && uevent_helper[count-1] == '\n')
  48                 uevent_helper[count-1] = '\0';
  49         return count;
  50 }
  51 KERNEL_ATTR_RW(uevent_helper);
  52 #endif
  53
  54 decl_subsys(kernel, NULL, NULL);
  55 EXPORT_SYMBOL_GPL(kernel_subsys);
  56
  57 static struct attribute * kernel_attrs[] = {
  58 #ifdef CONFIG_HOTPLUG
  59         &uevent_seqnum_attr.attr,
  60         &uevent_helper_attr.attr,
  61 #endif
  62         NULL
  63 };
  64
  65 static struct attribute_group kernel_attr_group = {
  66         .attrs = kernel_attrs,
  67 };
  68
  69 static int __init ksysfs_init(void)
  70 {
  71         int error = subsystem_register(&kernel_subsys);
  72         if (!error)
  73                 error = sysfs_create_group(&kernel_subsys.kset.kobj,
  74                                            &kernel_attr_group);
  75
  76         return error;
  77 }
  78
  79 core_initcall(ksysfs_init);