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); 80