include/linux/kobject.h

   1 /*
   2  * kobject.h - generic kernel object infrastructure.
   3  *
   4  * Copyright (c) 2002-2003      Patrick Mochel
   5  * Copyright (c) 2002-2003      Open Source Development Labs
   6  *
   7  * This file is released under the GPLv2.
   8  *
   9  *
  10  * Please read Documentation/kobject.txt before using the kobject
  11  * interface, ESPECIALLY the parts about reference counts and object
  12  * destructors.
  13  */
  14
  15 #ifndef _KOBJECT_H_
  16 #define _KOBJECT_H_
  17
  18 #ifdef __KERNEL__
  19
  20 #include <linux/types.h>
  21 #include <linux/list.h>
  22 #include <linux/sysfs.h>
  23 #include <linux/spinlock.h>
  24 #include <linux/rwsem.h>
  25 #include <linux/kref.h>
  26 #include <linux/kobject_uevent.h>
  27 #include <linux/kernel.h>
  28 #include <asm/atomic.h>
  29
  30 #define KOBJ_NAME_LEN   20
  31
  32 /* counter to tag the hotplug event, read only except for the kobject core */
  33 extern u64 hotplug_seqnum;
  34
  35 struct kobject {
  36         const char              * k_name;
  37         char                    name[KOBJ_NAME_LEN];
  38         struct kref             kref;
  39         struct list_head        entry;
  40         struct kobject          * parent;
  41         struct kset             * kset;
  42         struct kobj_type        * ktype;
  43         struct dentry           * dentry;
  44 };
  45
  46 extern int kobject_set_name(struct kobject *, const char *, ...)
  47         __attribute__((format(printf,2,3)));
  48
  49 static inline const char * kobject_name(const struct kobject * kobj)
  50 {
  51         return kobj->k_name;
  52 }
  53
  54 extern void kobject_init(struct kobject *);
  55 extern void kobject_cleanup(struct kobject *);
  56
  57 extern int kobject_add(struct kobject *);
  58 extern void kobject_del(struct kobject *);
  59
  60 extern int kobject_rename(struct kobject *, const char *new_name);
  61
  62 extern int kobject_register(struct kobject *);
  63 extern void kobject_unregister(struct kobject *);
  64
  65 extern struct kobject * kobject_get(struct kobject *);
  66 extern void kobject_put(struct kobject *);
  67
  68 extern char * kobject_get_path(struct kobject *, gfp_t);
  69
  70 struct kobj_type {
  71         void (*release)(struct kobject *);
  72         struct sysfs_ops        * sysfs_ops;
  73         struct attribute        ** default_attrs;
  74 };
  75
  76
  77 /**
  78  *      kset - a set of kobjects of a specific type, belonging
  79  *      to a specific subsystem.
  80  *
  81  *      All kobjects of a kset should be embedded in an identical
  82  *      type. This type may have a descriptor, which the kset points
  83  *      to. This allows there to exist sets of objects of the same
  84  *      type in different subsystems.
  85  *
  86  *      A subsystem does not have to be a list of only one type
  87  *      of object; multiple ksets can belong to one subsystem. All
  88  *      ksets of a subsystem share the subsystem's lock.
  89  *
  90  *      Each kset can support hotplugging; if it does, it will be given
  91  *      the opportunity to filter out specific kobjects from being
  92  *      reported, as well as to add its own "data" elements to the
  93  *      environment being passed to the hotplug helper.
  94  */
  95 struct kset_hotplug_ops {
  96         int (*filter)(struct kset *kset, struct kobject *kobj);
  97         const char *(*name)(struct kset *kset, struct kobject *kobj);
  98         int (*hotplug)(struct kset *kset, struct kobject *kobj, char **envp,
  99                         int num_envp, char *buffer, int buffer_size);
 100 };
 101
 102 struct kset {
 103         struct subsystem        * subsys;
 104         struct kobj_type        * ktype;
 105         struct list_head        list;
 106         spinlock_t              list_lock;
 107         struct kobject          kobj;
 108         struct kset_hotplug_ops * hotplug_ops;
 109 };
 110
 111
 112 extern void kset_init(struct kset * k);
 113 extern int kset_add(struct kset * k);
 114 extern int kset_register(struct kset * k);
 115 extern void kset_unregister(struct kset * k);
 116
 117 static inline struct kset * to_kset(struct kobject * kobj)
 118 {
 119         return kobj ? container_of(kobj,struct kset,kobj) : NULL;
 120 }
 121
 122 static inline struct kset * kset_get(struct kset * k)
 123 {
 124         return k ? to_kset(kobject_get(&k->kobj)) : NULL;
 125 }
 126
 127 static inline void kset_put(struct kset * k)
 128 {
 129         kobject_put(&k->kobj);
 130 }
 131
 132 static inline struct kobj_type * get_ktype(struct kobject * k)
 133 {
 134         if (k->kset && k->kset->ktype)
 135                 return k->kset->ktype;
 136         else
 137                 return k->ktype;
 138 }
 139
 140 extern struct kobject * kset_find_obj(struct kset *, const char *);
 141
 142
 143 /**
 144  * Use this when initializing an embedded kset with no other
 145  * fields to initialize.
 146  */
 147 #define set_kset_name(str)      .kset = { .kobj = { .name = str } }
 148
 149
 150
 151 struct subsystem {
 152         struct kset             kset;
 153         struct rw_semaphore     rwsem;
 154 };
 155
 156 #define decl_subsys(_name,_type,_hotplug_ops) \
 157 struct subsystem _name##_subsys = { \
 158         .kset = { \
 159                 .kobj = { .name = __stringify(_name) }, \
 160                 .ktype = _type, \
 161                 .hotplug_ops =_hotplug_ops, \
 162         } \
 163 }
 164 #define decl_subsys_name(_varname,_name,_type,_hotplug_ops) \
 165 struct subsystem _varname##_subsys = { \
 166         .kset = { \
 167                 .kobj = { .name = __stringify(_name) }, \
 168                 .ktype = _type, \
 169                 .hotplug_ops =_hotplug_ops, \
 170         } \
 171 }
 172
 173 /* The global /sys/kernel/ subsystem for people to chain off of */
 174 extern struct subsystem kernel_subsys;
 175
 176 /**
 177  * Helpers for setting the kset of registered objects.
 178  * Often, a registered object belongs to a kset embedded in a
 179  * subsystem. These do no magic, just make the resulting code
 180  * easier to follow.
 181  */
 182
 183 /**
 184  *      kobj_set_kset_s(obj,subsys) - set kset for embedded kobject.
 185  *      @obj:           ptr to some object type.
 186  *      @subsys:        a subsystem object (not a ptr).
 187  *
 188  *      Can be used for any object type with an embedded ->kobj.
 189  */
 190
 191 #define kobj_set_kset_s(obj,subsys) \
 192         (obj)->kobj.kset = &(subsys).kset
 193
 194 /**
 195  *      kset_set_kset_s(obj,subsys) - set kset for embedded kset.
 196  *      @obj:           ptr to some object type.
 197  *      @subsys:        a subsystem object (not a ptr).
 198  *
 199  *      Can be used for any object type with an embedded ->kset.
 200  *      Sets the kset of @obj's  embedded kobject (via its embedded
 201  *      kset) to @subsys.kset. This makes @obj a member of that
 202  *      kset.
 203  */
 204
 205 #define kset_set_kset_s(obj,subsys) \
 206         (obj)->kset.kobj.kset = &(subsys).kset
 207
 208 /**
 209  *      subsys_set_kset(obj,subsys) - set kset for subsystem
 210  *      @obj:           ptr to some object type.
 211  *      @subsys:        a subsystem object (not a ptr).
 212  *
 213  *      Can be used for any object type with an embedded ->subsys.
 214  *      Sets the kset of @obj's kobject to @subsys.kset. This makes
 215  *      the object a member of that kset.
 216  */
 217
 218 #define subsys_set_kset(obj,_subsys) \
 219         (obj)->subsys.kset.kobj.kset = &(_subsys).kset
 220
 221 extern void subsystem_init(struct subsystem *);
 222 extern int subsystem_register(struct subsystem *);
 223 extern void subsystem_unregister(struct subsystem *);
 224
 225 static inline struct subsystem * subsys_get(struct subsystem * s)
 226 {
 227         return s ? container_of(kset_get(&s->kset),struct subsystem,kset) : NULL;
 228 }
 229
 230 static inline void subsys_put(struct subsystem * s)
 231 {
 232         kset_put(&s->kset);
 233 }
 234
 235 struct subsys_attribute {
 236         struct attribute attr;
 237         ssize_t (*show)(struct subsystem *, char *);
 238         ssize_t (*store)(struct subsystem *, const char *, size_t);
 239 };
 240
 241 extern int subsys_create_file(struct subsystem * , struct subsys_attribute *);
 242 extern void subsys_remove_file(struct subsystem * , struct subsys_attribute *);
 243
 244 #ifdef CONFIG_HOTPLUG
 245 void kobject_hotplug(struct kobject *kobj, enum kobject_action action);
 246 int add_hotplug_env_var(char **envp, int num_envp, int *cur_index,
 247                         char *buffer, int buffer_size, int *cur_len,
 248                         const char *format, ...)
 249         __attribute__((format (printf, 7, 8)));
 250 #else
 251 static inline void kobject_hotplug(struct kobject *kobj, enum kobject_action action) { }
 252 static inline int add_hotplug_env_var(char **envp, int num_envp, int *cur_index,
 253                                       char *buffer, int buffer_size, int *cur_len,
 254                                       const char *format, ...)
 255 { return 0; }
 256 #endif
 257
 258 #endif /* __KERNEL__ */
 259 #endif /* _KOBJECT_H_ */