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 int __class_register(struct class *cls, struct lock_class_key *key)
 139 {
 140         struct class_private *cp;
 141         int error;
 142
 143         pr_debug("device class '%s': registering\n", cls->name);
 144
 145         cp = kzalloc(sizeof(*cp), GFP_KERNEL);
 146         if (!cp)
 147                 return -ENOMEM;
 148         INIT_LIST_HEAD(&cp->class_devices);
 149         INIT_LIST_HEAD(&cp->class_interfaces);
 150         kset_init(&cp->class_dirs);
 151         __mutex_init(&cp->class_mutex, "struct class mutex", key);
 152         error = kobject_set_name(&cp->class_subsys.kobj, "%s", cls->name);
 153         if (error) {
 154                 kfree(cp);
 155                 return error;
 156         }
 157
 158         /* set the default /sys/dev directory for devices of this class */
 159         if (!cls->dev_kobj)
 160                 cls->dev_kobj = sysfs_dev_char_kobj;
 161
 162 #if defined(CONFIG_SYSFS_DEPRECATED) && defined(CONFIG_BLOCK)
 163         /* let the block class directory show up in the root of sysfs */
 164         if (cls != &block_class)
 165                 cp->class_subsys.kobj.kset = class_kset;
 166 #else
 167         cp->class_subsys.kobj.kset = class_kset;
 168 #endif
 169         cp->class_subsys.kobj.ktype = &class_ktype;
 170         cp->class = cls;
 171         cls->p = cp;
 172
 173         error = kset_register(&cp->class_subsys);
 174         if (error) {
 175                 kfree(cp);
 176                 return error;
 177         }
 178         error = add_class_attrs(class_get(cls));
 179         class_put(cls);
 180         return error;
 181 }
 182 EXPORT_SYMBOL_GPL(__class_register);
 183
 184 void class_unregister(struct class *cls)
 185 {
 186         pr_debug("device class '%s': unregistering\n", cls->name);
 187         remove_class_attrs(cls);
 188         kset_unregister(&cls->p->class_subsys);
 189 }
 190
 191 static void class_create_release(struct class *cls)
 192 {
 193         pr_debug("%s called for %s\n", __func__, cls->name);
 194         kfree(cls);
 195 }
 196
 197 /**
 198  * class_create - create a struct class structure
 199  * @owner: pointer to the module that is to "own" this struct class
 200  * @name: pointer to a string for the name of this class.
 201  * @key: the lock_class_key for this class; used by mutex lock debugging
 202  *
 203  * This is used to create a struct class pointer that can then be used
 204  * in calls to device_create().
 205  *
 206  * Note, the pointer created here is to be destroyed when finished by
 207  * making a call to class_destroy().
 208  */
 209 struct class *__class_create(struct module *owner, const char *name,
 210                              struct lock_class_key *key)
 211 {
 212         struct class *cls;
 213         int retval;
 214
 215         cls = kzalloc(sizeof(*cls), GFP_KERNEL);
 216         if (!cls) {
 217                 retval = -ENOMEM;
 218                 goto error;
 219         }
 220
 221         cls->name = name;
 222         cls->owner = owner;
 223         cls->class_release = class_create_release;
 224
 225         retval = __class_register(cls, key);
 226         if (retval)
 227                 goto error;
 228
 229         return cls;
 230
 231 error:
 232         kfree(cls);
 233         return ERR_PTR(retval);
 234 }
 235 EXPORT_SYMBOL_GPL(__class_create);
 236
 237 /**
 238  * class_destroy - destroys a struct class structure
 239  * @cls: pointer to the struct class that is to be destroyed
 240  *
 241  * Note, the pointer to be destroyed must have been created with a call
 242  * to class_create().
 243  */
 244 void class_destroy(struct class *cls)
 245 {
 246         if ((cls == NULL) || (IS_ERR(cls)))
 247                 return;
 248
 249         class_unregister(cls);
 250 }
 251
 252 #ifdef CONFIG_SYSFS_DEPRECATED
 253 char *make_class_name(const char *name, struct kobject *kobj)
 254 {
 255         char *class_name;
 256         int size;
 257
 258         size = strlen(name) + strlen(kobject_name(kobj)) + 2;
 259
 260         class_name = kmalloc(size, GFP_KERNEL);
 261         if (!class_name)
 262                 return NULL;
 263
 264         strcpy(class_name, name);
 265         strcat(class_name, ":");
 266         strcat(class_name, kobject_name(kobj));
 267         return class_name;
 268 }
 269 #endif
 270
 271 /**
 272  * class_for_each_device - device iterator
 273  * @class: the class we're iterating
 274  * @start: the device to start with in the list, if any.
 275  * @data: data for the callback
 276  * @fn: function to be called for each device
 277  *
 278  * Iterate over @class's list of devices, and call @fn for each,
 279  * passing it @data.  If @start is set, the list iteration will start
 280  * there, otherwise if it is NULL, the iteration starts at the
 281  * beginning of the list.
 282  *
 283  * We check the return of @fn each time. If it returns anything
 284  * other than 0, we break out and return that value.
 285  *
 286  * Note, we hold class->class_mutex in this function, so it can not be
 287  * re-acquired in @fn, otherwise it will self-deadlocking. For
 288  * example, calls to add or remove class members would be verboten.
 289  */
 290 int class_for_each_device(struct class *class, struct device *start,
 291                           void *data, int (*fn)(struct device *, void *))
 292 {
 293         struct device *dev;
 294         int error = 0;
 295
 296         if (!class)
 297                 return -EINVAL;
 298         if (!class->p) {
 299                 WARN(1, "%s called for class '%s' before it was initialized",
 300                      __func__, class->name);
 301                 return -EINVAL;
 302         }
 303
 304         mutex_lock(&class->p->class_mutex);
 305         list_for_each_entry(dev, &class->p->class_devices, node) {
 306                 if (start) {
 307                         if (start == dev)
 308                                 start = NULL;
 309                         continue;
 310                 }
 311                 dev = get_device(dev);
 312                 error = fn(dev, data);
 313                 put_device(dev);
 314                 if (error)
 315                         break;
 316         }
 317         mutex_unlock(&class->p->class_mutex);
 318
 319         return error;
 320 }
 321 EXPORT_SYMBOL_GPL(class_for_each_device);
 322
 323 /**
 324  * class_find_device - device iterator for locating a particular device
 325  * @class: the class we're iterating
 326  * @start: Device to begin with
 327  * @data: data for the match function
 328  * @match: function to check device
 329  *
 330  * This is similar to the class_for_each_dev() function above, but it
 331  * returns a reference to a device that is 'found' for later use, as
 332  * determined by the @match callback.
 333  *
 334  * The callback should return 0 if the device doesn't match and non-zero
 335  * if it does.  If the callback returns non-zero, this function will
 336  * return to the caller and not iterate over any more devices.
 337  *
 338  * Note, you will need to drop the reference with put_device() after use.
 339  *
 340  * We hold class->class_mutex in this function, so it can not be
 341  * re-acquired in @match, otherwise it will self-deadlocking. For
 342  * example, calls to add or remove class members would be verboten.
 343  */
 344 struct device *class_find_device(struct class *class, struct device *start,
 345                                  void *data,
 346                                  int (*match)(struct device *, void *))
 347 {
 348         struct device *dev;
 349         int found = 0;
 350
 351         if (!class)
 352                 return NULL;
 353         if (!class->p) {
 354                 WARN(1, "%s called for class '%s' before it was initialized",
 355                      __func__, class->name);
 356                 return NULL;
 357         }
 358
 359         mutex_lock(&class->p->class_mutex);
 360         list_for_each_entry(dev, &class->p->class_devices, node) {
 361                 if (start) {
 362                         if (start == dev)
 363                                 start = NULL;
 364                         continue;
 365                 }
 366                 dev = get_device(dev);
 367                 if (match(dev, data)) {
 368                         found = 1;
 369                         break;
 370                 } else
 371                         put_device(dev);
 372         }
 373         mutex_unlock(&class->p->class_mutex);
 374
 375         return found ? dev : NULL;
 376 }
 377 EXPORT_SYMBOL_GPL(class_find_device);
 378
 379 int class_interface_register(struct class_interface *class_intf)
 380 {
 381         struct class *parent;
 382         struct device *dev;
 383
 384         if (!class_intf || !class_intf->class)
 385                 return -ENODEV;
 386
 387         parent = class_get(class_intf->class);
 388         if (!parent)
 389                 return -EINVAL;
 390
 391         mutex_lock(&parent->p->class_mutex);
 392         list_add_tail(&class_intf->node, &parent->p->class_interfaces);
 393         if (class_intf->add_dev) {
 394                 list_for_each_entry(dev, &parent->p->class_devices, node)
 395                         class_intf->add_dev(dev, class_intf);
 396         }
 397         mutex_unlock(&parent->p->class_mutex);
 398
 399         return 0;
 400 }
 401
 402 void class_interface_unregister(struct class_interface *class_intf)
 403 {
 404         struct class *parent = class_intf->class;
 405         struct device *dev;
 406
 407         if (!parent)
 408                 return;
 409
 410         mutex_lock(&parent->p->class_mutex);
 411         list_del_init(&class_intf->node);
 412         if (class_intf->remove_dev) {
 413                 list_for_each_entry(dev, &parent->p->class_devices, node)
 414                         class_intf->remove_dev(dev, class_intf);
 415         }
 416         mutex_unlock(&parent->p->class_mutex);
 417
 418         class_put(parent);
 419 }
 420
 421 int __init classes_init(void)
 422 {
 423         class_kset = kset_create_and_add("class", NULL, NULL);
 424         if (!class_kset)
 425                 return -ENOMEM;
 426         return 0;
 427 }
 428
 429 EXPORT_SYMBOL_GPL(class_create_file);
 430 EXPORT_SYMBOL_GPL(class_remove_file);
 431 EXPORT_SYMBOL_GPL(class_unregister);
 432 EXPORT_SYMBOL_GPL(class_destroy);
 433
 434 EXPORT_SYMBOL_GPL(class_interface_register);
 435 EXPORT_SYMBOL_GPL(class_interface_unregister);