drivers/base/class.c

   1 /*
   2  * class.c - basic device class management
   3  *
   4  * Copyright (c) 2002-3 Patrick Mochel
   5  * Copyright (c) 2002-3 Open Source Development Labs
   6  * Copyright (c) 2003-2004 Greg Kroah-Hartman
   7  * Copyright (c) 2003-2004 IBM Corp.
   8  *
   9  * This file is released under the GPLv2
  10  *
  11  */
  12
  13 #include <linux/device.h>
  14 #include <linux/module.h>
  15 #include <linux/init.h>
  16 #include <linux/string.h>
  17 #include <linux/kdev_t.h>
  18 #include <linux/err.h>
  19 #include <linux/slab.h>
  20 #include <linux/genhd.h>
  21 #include <linux/mutex.h>
  22 #include "base.h"
  23
  24 #define to_class_attr(_attr) container_of(_attr, struct class_attribute, attr)
  25
  26 static ssize_t class_attr_show(struct kobject *kobj, struct attribute *attr,
  27                                char *buf)
  28 {
  29         struct class_attribute *class_attr = to_class_attr(attr);
  30         struct class_private *cp = to_class(kobj);
  31         ssize_t ret = -EIO;
  32
  33         if (class_attr->show)
  34                 ret = class_attr->show(cp->class, buf);
  35         return ret;
  36 }
  37
  38 static ssize_t class_attr_store(struct kobject *kobj, struct attribute *attr,
  39                                 const char *buf, size_t count)
  40 {
  41         struct class_attribute *class_attr = to_class_attr(attr);
  42         struct class_private *cp = to_class(kobj);
  43         ssize_t ret = -EIO;
  44
  45         if (class_attr->store)
  46                 ret = class_attr->store(cp->class, buf, count);
  47         return ret;
  48 }
  49
  50 static void class_release(struct kobject *kobj)
  51 {
  52         struct class_private *cp = to_class(kobj);
  53         struct class *class = cp->class;
  54
  55         pr_debug("class '%s': release.\n", class->name);
  56
  57         if (class->class_release)
  58                 class->class_release(class);
  59         else
  60                 pr_debug("class '%s' does not have a release() function, "
  61                          "be careful\n", class->name);
  62 }
  63
  64 static struct sysfs_ops class_sysfs_ops = {
  65         .show   = class_attr_show,
  66         .store  = class_attr_store,
  67 };
  68
  69 static struct kobj_type class_ktype = {
  70         .sysfs_ops      = &class_sysfs_ops,
  71         .release        = class_release,
  72 };
  73
  74 /* Hotplug events for classes go to the class class_subsys */
  75 static struct kset *class_kset;
  76
  77
  78 int class_create_file(struct class *cls, const struct class_attribute *attr)
  79 {
  80         int error;
  81         if (cls)
  82                 error = sysfs_create_file(&cls->p->class_subsys.kobj,
  83                                           &attr->attr);
  84         else
  85                 error = -EINVAL;
  86         return error;
  87 }
  88
  89 void class_remove_file(struct class *cls, const struct class_attribute *attr)
  90 {
  91         if (cls)
  92                 sysfs_remove_file(&cls->p->class_subsys.kobj, &attr->attr);
  93 }
  94
  95 static struct class *class_get(struct class *cls)
  96 {
  97         if (cls)
  98                 kset_get(&cls->p->class_subsys);
  99         return cls;
 100 }
 101
 102 static void class_put(struct class *cls)
 103 {
 104         if (cls)
 105                 kset_put(&cls->p->class_subsys);
 106 }
 107
 108 static int add_class_attrs(struct class *cls)
 109 {
 110         int i;
 111         int error = 0;
 112
 113         if (cls->class_attrs) {
 114                 for (i = 0; attr_name(cls->class_attrs[i]); i++) {
 115                         error = class_create_file(cls, &cls->class_attrs[i]);
 116                         if (error)
 117                                 goto error;
 118                 }
 119         }
 120 done:
 121         return error;
 122 error:
 123         while (--i >= 0)
 124                 class_remove_file(cls, &cls->class_attrs[i]);
 125         goto done;
 126 }
 127
 128 static void remove_class_attrs(struct class *cls)
 129 {
 130         int i;
 131
 132         if (cls->class_attrs) {
 133                 for (i = 0; attr_name(cls->class_attrs[i]); i++)
 134                         class_remove_file(cls, &cls->class_attrs[i]);
 135         }
 136 }
 137
 138 static void klist_class_dev_get(struct klist_node *n)
 139 {
 140         struct device *dev = container_of(n, struct device, knode_class);
 141
 142         get_device(dev);
 143 }
 144
 145 static void klist_class_dev_put(struct klist_node *n)
 146 {
 147         struct device *dev = container_of(n, struct device, knode_class);
 148
 149         put_device(dev);
 150 }
 151
 152 int __class_register(struct class *cls, struct lock_class_key *key)
 153 {
 154         struct class_private *cp;
 155         int error;
 156
 157         pr_debug("device class '%s': registering\n", cls->name);
 158
 159         cp = kzalloc(sizeof(*cp), GFP_KERNEL);
 160         if (!cp)
 161                 return -ENOMEM;
 162         klist_init(&cp->class_devices, klist_class_dev_get, klist_class_dev_put);
 163         INIT_LIST_HEAD(&cp->class_interfaces);
 164         kset_init(&cp->class_dirs);
 165         __mutex_init(&cp->class_mutex, "struct class mutex", key);
 166         error = kobject_set_name(&cp->class_subsys.kobj, "%s", cls->name);
 167         if (error) {
 168                 kfree(cp);
 169                 return error;
 170         }
 171
 172         /* set the default /sys/dev directory for devices of this class */
 173         if (!cls->dev_kobj)
 174                 cls->dev_kobj = sysfs_dev_char_kobj;
 175
 176 #if defined(CONFIG_SYSFS_DEPRECATED) && defined(CONFIG_BLOCK)
 177         /* let the block class directory show up in the root of sysfs */
 178         if (cls != &block_class)
 179                 cp->class_subsys.kobj.kset = class_kset;
 180 #else
 181         cp->class_subsys.kobj.kset = class_kset;
 182 #endif
 183         cp->class_subsys.kobj.ktype = &class_ktype;
 184         cp->class = cls;
 185         cls->p = cp;
 186
 187         error = kset_register(&cp->class_subsys);
 188         if (error) {
 189                 kfree(cp);
 190                 return error;
 191         }
 192         error = add_class_attrs(class_get(cls));
 193         class_put(cls);
 194         return error;
 195 }
 196 EXPORT_SYMBOL_GPL(__class_register);
 197
 198 void class_unregister(struct class *cls)
 199 {
 200         pr_debug("device class '%s': unregistering\n", cls->name);
 201         remove_class_attrs(cls);
 202         kset_unregister(&cls->p->class_subsys);
 203 }
 204
 205 static void class_create_release(struct class *cls)
 206 {
 207         pr_debug("%s called for %s\n", __func__, cls->name);
 208         kfree(cls);
 209 }
 210
 211 /**
 212  * class_create - create a struct class structure
 213  * @owner: pointer to the module that is to "own" this struct class
 214  * @name: pointer to a string for the name of this class.
 215  * @key: the lock_class_key for this class; used by mutex lock debugging
 216  *
 217  * This is used to create a struct class pointer that can then be used
 218  * in calls to device_create().
 219  *
 220  * Note, the pointer created here is to be destroyed when finished by
 221  * making a call to class_destroy().
 222  */
 223 struct class *__class_create(struct module *owner, const char *name,
 224                              struct lock_class_key *key)
 225 {
 226         struct class *cls;
 227         int retval;
 228
 229         cls = kzalloc(sizeof(*cls), GFP_KERNEL);
 230         if (!cls) {
 231                 retval = -ENOMEM;
 232                 goto error;
 233         }
 234
 235         cls->name = name;
 236         cls->owner = owner;
 237         cls->class_release = class_create_release;
 238
 239         retval = __class_register(cls, key);
 240         if (retval)
 241                 goto error;
 242
 243         return cls;
 244
 245 error:
 246         kfree(cls);
 247         return ERR_PTR(retval);
 248 }
 249 EXPORT_SYMBOL_GPL(__class_create);
 250
 251 /**
 252  * class_destroy - destroys a struct class structure
 253  * @cls: pointer to the struct class that is to be destroyed
 254  *
 255  * Note, the pointer to be destroyed must have been created with a call
 256  * to class_create().
 257  */
 258 void class_destroy(struct class *cls)
 259 {
 260         if ((cls == NULL) || (IS_ERR(cls)))
 261                 return;
 262
 263         class_unregister(cls);
 264 }
 265
 266 #ifdef CONFIG_SYSFS_DEPRECATED
 267 char *make_class_name(const char *name, struct kobject *kobj)
 268 {
 269         char *class_name;
 270         int size;
 271
 272         size = strlen(name) + strlen(kobject_name(kobj)) + 2;
 273
 274         class_name = kmalloc(size, GFP_KERNEL);
 275         if (!class_name)
 276                 return NULL;
 277
 278         strcpy(class_name, name);
 279         strcat(class_name, ":");
 280         strcat(class_name, kobject_name(kobj));
 281         return class_name;
 282 }
 283 #endif
 284
 285 /**
 286  * class_dev_iter_init - initialize class device iterator
 287  * @iter: class iterator to initialize
 288  * @class: the class we wanna iterate over
 289  * @start: the device to start iterating from, if any
 290  * @type: device_type of the devices to iterate over, NULL for all
 291  *
 292  * Initialize class iterator @iter such that it iterates over devices
 293  * of @class.  If @start is set, the list iteration will start there,
 294  * otherwise if it is NULL, the iteration starts at the beginning of
 295  * the list.
 296  */
 297 void class_dev_iter_init(struct class_dev_iter *iter, struct class *class,
 298                          struct device *start, const struct device_type *type)
 299 {
 300         struct klist_node *start_knode = NULL;
 301
 302         if (start)
 303                 start_knode = &start->knode_class;
 304         klist_iter_init_node(&class->p->class_devices, &iter->ki, start_knode);
 305         iter->type = type;
 306 }
 307 EXPORT_SYMBOL_GPL(class_dev_iter_init);
 308
 309 /**
 310  * class_dev_iter_next - iterate to the next device
 311  * @iter: class iterator to proceed
 312  *
 313  * Proceed @iter to the next device and return it.  Returns NULL if
 314  * iteration is complete.
 315  *
 316  * The returned device is referenced and won't be released till
 317  * iterator is proceed to the next device or exited.  The caller is
 318  * free to do whatever it wants to do with the device including
 319  * calling back into class code.
 320  */
 321 struct device *class_dev_iter_next(struct class_dev_iter *iter)
 322 {
 323         struct klist_node *knode;
 324         struct device *dev;
 325
 326         while (1) {
 327                 knode = klist_next(&iter->ki);
 328                 if (!knode)
 329                         return NULL;
 330                 dev = container_of(knode, struct device, knode_class);
 331                 if (!iter->type || iter->type == dev->type)
 332                         return dev;
 333         }
 334 }
 335 EXPORT_SYMBOL_GPL(class_dev_iter_next);
 336
 337 /**
 338  * class_dev_iter_exit - finish iteration
 339  * @iter: class iterator to finish
 340  *
 341  * Finish an iteration.  Always call this function after iteration is
 342  * complete whether the iteration ran till the end or not.
 343  */
 344 void class_dev_iter_exit(struct class_dev_iter *iter)
 345 {
 346         klist_iter_exit(&iter->ki);
 347 }
 348 EXPORT_SYMBOL_GPL(class_dev_iter_exit);
 349
 350 /**
 351  * class_for_each_device - device iterator
 352  * @class: the class we're iterating
 353  * @start: the device to start with in the list, if any.
 354  * @data: data for the callback
 355  * @fn: function to be called for each device
 356  *
 357  * Iterate over @class's list of devices, and call @fn for each,
 358  * passing it @data.  If @start is set, the list iteration will start
 359  * there, otherwise if it is NULL, the iteration starts at the
 360  * beginning of the list.
 361  *
 362  * We check the return of @fn each time. If it returns anything
 363  * other than 0, we break out and return that value.
 364  *
 365  * @fn is allowed to do anything including calling back into class
 366  * code.  There's no locking restriction.
 367  */
 368 int class_for_each_device(struct class *class, struct device *start,
 369                           void *data, int (*fn)(struct device *, void *))
 370 {
 371         struct class_dev_iter iter;
 372         struct device *dev;
 373         int error = 0;
 374
 375         if (!class)
 376                 return -EINVAL;
 377         if (!class->p) {
 378                 WARN(1, "%s called for class '%s' before it was initialized",
 379                      __func__, class->name);
 380                 return -EINVAL;
 381         }
 382
 383         class_dev_iter_init(&iter, class, start, NULL);
 384         while ((dev = class_dev_iter_next(&iter))) {
 385                 error = fn(dev, data);
 386                 if (error)
 387                         break;
 388         }
 389         class_dev_iter_exit(&iter);
 390
 391         return error;
 392 }
 393 EXPORT_SYMBOL_GPL(class_for_each_device);
 394
 395 /**
 396  * class_find_device - device iterator for locating a particular device
 397  * @class: the class we're iterating
 398  * @start: Device to begin with
 399  * @data: data for the match function
 400  * @match: function to check device
 401  *
 402  * This is similar to the class_for_each_dev() function above, but it
 403  * returns a reference to a device that is 'found' for later use, as
 404  * determined by the @match callback.
 405  *
 406  * The callback should return 0 if the device doesn't match and non-zero
 407  * if it does.  If the callback returns non-zero, this function will
 408  * return to the caller and not iterate over any more devices.
 409  *
 410  * Note, you will need to drop the reference with put_device() after use.
 411  *
 412  * @fn is allowed to do anything including calling back into class
 413  * code.  There's no locking restriction.
 414  */
 415 struct device *class_find_device(struct class *class, struct device *start,
 416                                  void *data,
 417                                  int (*match)(struct device *, void *))
 418 {
 419         struct class_dev_iter iter;
 420         struct device *dev;
 421
 422         if (!class)
 423                 return NULL;
 424         if (!class->p) {
 425                 WARN(1, "%s called for class '%s' before it was initialized",
 426                      __func__, class->name);
 427                 return NULL;
 428         }
 429
 430         class_dev_iter_init(&iter, class, start, NULL);
 431         while ((dev = class_dev_iter_next(&iter))) {
 432                 if (match(dev, data)) {
 433                         get_device(dev);
 434                         break;
 435                 }
 436         }
 437         class_dev_iter_exit(&iter);
 438
 439         return dev;
 440 }
 441 EXPORT_SYMBOL_GPL(class_find_device);
 442
 443 int class_interface_register(struct class_interface *class_intf)
 444 {
 445         struct class *parent;
 446         struct class_dev_iter iter;
 447         struct device *dev;
 448
 449         if (!class_intf || !class_intf->class)
 450                 return -ENODEV;
 451
 452         parent = class_get(class_intf->class);
 453         if (!parent)
 454                 return -EINVAL;
 455
 456         mutex_lock(&parent->p->class_mutex);
 457         list_add_tail(&class_intf->node, &parent->p->class_interfaces);
 458         if (class_intf->add_dev) {
 459                 class_dev_iter_init(&iter, parent, NULL, NULL);
 460                 while ((dev = class_dev_iter_next(&iter)))
 461                         class_intf->add_dev(dev, class_intf);
 462                 class_dev_iter_exit(&iter);
 463         }
 464         mutex_unlock(&parent->p->class_mutex);
 465
 466         return 0;
 467 }
 468
 469 void class_interface_unregister(struct class_interface *class_intf)
 470 {
 471         struct class *parent = class_intf->class;
 472         struct class_dev_iter iter;
 473         struct device *dev;
 474
 475         if (!parent)
 476                 return;
 477
 478         mutex_lock(&parent->p->class_mutex);
 479         list_del_init(&class_intf->node);
 480         if (class_intf->remove_dev) {
 481                 class_dev_iter_init(&iter, parent, NULL, NULL);
 482                 while ((dev = class_dev_iter_next(&iter)))
 483                         class_intf->remove_dev(dev, class_intf);
 484                 class_dev_iter_exit(&iter);
 485         }
 486         mutex_unlock(&parent->p->class_mutex);
 487
 488         class_put(parent);
 489 }
 490
 491 int __init classes_init(void)
 492 {
 493         class_kset = kset_create_and_add("class", NULL, NULL);
 494         if (!class_kset)
 495                 return -ENOMEM;
 496         return 0;
 497 }
 498
 499 EXPORT_SYMBOL_GPL(class_create_file);
 500 EXPORT_SYMBOL_GPL(class_remove_file);
 501 EXPORT_SYMBOL_GPL(class_unregister);
 502 EXPORT_SYMBOL_GPL(class_destroy);
 503
 504 EXPORT_SYMBOL_GPL(class_interface_register);
 505 EXPORT_SYMBOL_GPL(class_interface_unregister);