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 "base.h"
  22
  23 #define to_class_attr(_attr) container_of(_attr, struct class_attribute, attr)
  24
  25 static ssize_t class_attr_show(struct kobject *kobj, struct attribute *attr,
  26                                char *buf)
  27 {
  28         struct class_attribute *class_attr = to_class_attr(attr);
  29         struct class_private *cp = to_class(kobj);
  30         ssize_t ret = -EIO;
  31
  32         if (class_attr->show)
  33                 ret = class_attr->show(cp->class, buf);
  34         return ret;
  35 }
  36
  37 static ssize_t class_attr_store(struct kobject *kobj, struct attribute *attr,
  38                                 const char *buf, size_t count)
  39 {
  40         struct class_attribute *class_attr = to_class_attr(attr);
  41         struct class_private *cp = to_class(kobj);
  42         ssize_t ret = -EIO;
  43
  44         if (class_attr->store)
  45                 ret = class_attr->store(cp->class, buf, count);
  46         return ret;
  47 }
  48
  49 static void class_release(struct kobject *kobj)
  50 {
  51         struct class_private *cp = to_class(kobj);
  52         struct class *class = cp->class;
  53
  54         pr_debug("class '%s': release.\n", class->name);
  55
  56         if (class->class_release)
  57                 class->class_release(class);
  58         else
  59                 pr_debug("class '%s' does not have a release() function, "
  60                          "be careful\n", class->name);
  61 }
  62
  63 static struct sysfs_ops class_sysfs_ops = {
  64         .show   = class_attr_show,
  65         .store  = class_attr_store,
  66 };
  67
  68 static struct kobj_type class_ktype = {
  69         .sysfs_ops      = &class_sysfs_ops,
  70         .release        = class_release,
  71 };
  72
  73 /* Hotplug events for classes go to the class_obj subsys */
  74 static struct kset *class_kset;
  75
  76
  77 int class_create_file(struct class *cls, const struct class_attribute *attr)
  78 {
  79         int error;
  80         if (cls)
  81                 error = sysfs_create_file(&cls->p->subsys.kobj, &attr->attr);
  82         else
  83                 error = -EINVAL;
  84         return error;
  85 }
  86
  87 void class_remove_file(struct class *cls, const struct class_attribute *attr)
  88 {
  89         if (cls)
  90                 sysfs_remove_file(&cls->p->subsys.kobj, &attr->attr);
  91 }
  92
  93 static struct class *class_get(struct class *cls)
  94 {
  95         if (cls)
  96                 kset_get(&cls->p->subsys);
  97         return cls;
  98 }
  99
 100 static void class_put(struct class *cls)
 101 {
 102         if (cls)
 103                 kset_put(&cls->p->subsys);
 104 }
 105
 106 static int add_class_attrs(struct class *cls)
 107 {
 108         int i;
 109         int error = 0;
 110
 111         if (cls->class_attrs) {
 112                 for (i = 0; attr_name(cls->class_attrs[i]); i++) {
 113                         error = class_create_file(cls, &cls->class_attrs[i]);
 114                         if (error)
 115                                 goto error;
 116                 }
 117         }
 118 done:
 119         return error;
 120 error:
 121         while (--i >= 0)
 122                 class_remove_file(cls, &cls->class_attrs[i]);
 123         goto done;
 124 }
 125
 126 static void remove_class_attrs(struct class *cls)
 127 {
 128         int i;
 129
 130         if (cls->class_attrs) {
 131                 for (i = 0; attr_name(cls->class_attrs[i]); i++)
 132                         class_remove_file(cls, &cls->class_attrs[i]);
 133         }
 134 }
 135
 136 int class_register(struct class *cls)
 137 {
 138         struct class_private *cp;
 139         int error;
 140
 141         pr_debug("device class '%s': registering\n", cls->name);
 142
 143         cp = kzalloc(sizeof(*cp), GFP_KERNEL);
 144         if (!cp)
 145                 return -ENOMEM;
 146         INIT_LIST_HEAD(&cp->class_devices);
 147         INIT_LIST_HEAD(&cp->class_interfaces);
 148         kset_init(&cp->class_dirs);
 149         init_MUTEX(&cp->sem);
 150         error = kobject_set_name(&cp->subsys.kobj, "%s", cls->name);
 151         if (error) {
 152                 kfree(cp);
 153                 return error;
 154         }
 155
 156         /* set the default /sys/dev directory for devices of this class */
 157         if (!cls->dev_kobj)
 158                 cls->dev_kobj = sysfs_dev_char_kobj;
 159
 160 #if defined(CONFIG_SYSFS_DEPRECATED) && defined(CONFIG_BLOCK)
 161         /* let the block class directory show up in the root of sysfs */
 162         if (cls != &block_class)
 163                 cp->subsys.kobj.kset = class_kset;
 164 #else
 165         cp->subsys.kobj.kset = class_kset;
 166 #endif
 167         cp->subsys.kobj.ktype = &class_ktype;
 168         cp->class = cls;
 169         cls->p = cp;
 170
 171         error = kset_register(&cp->subsys);
 172         if (error) {
 173                 kfree(cp);
 174                 return error;
 175         }
 176         error = add_class_attrs(class_get(cls));
 177         class_put(cls);
 178         return error;
 179 }
 180
 181 void class_unregister(struct class *cls)
 182 {
 183         pr_debug("device class '%s': unregistering\n", cls->name);
 184         remove_class_attrs(cls);
 185         kset_unregister(&cls->p->subsys);
 186 }
 187
 188 static void class_create_release(struct class *cls)
 189 {
 190         pr_debug("%s called for %s\n", __func__, cls->name);
 191         kfree(cls);
 192 }
 193
 194 /**
 195  * class_create - create a struct class structure
 196  * @owner: pointer to the module that is to "own" this struct class
 197  * @name: pointer to a string for the name of this class.
 198  *
 199  * This is used to create a struct class pointer that can then be used
 200  * in calls to device_create().
 201  *
 202  * Note, the pointer created here is to be destroyed when finished by
 203  * making a call to class_destroy().
 204  */
 205 struct class *class_create(struct module *owner, const char *name)
 206 {
 207         struct class *cls;
 208         int retval;
 209
 210         cls = kzalloc(sizeof(*cls), GFP_KERNEL);
 211         if (!cls) {
 212                 retval = -ENOMEM;
 213                 goto error;
 214         }
 215
 216         cls->name = name;
 217         cls->owner = owner;
 218         cls->class_release = class_create_release;
 219
 220         retval = class_register(cls);
 221         if (retval)
 222                 goto error;
 223
 224         return cls;
 225
 226 error:
 227         kfree(cls);
 228         return ERR_PTR(retval);
 229 }
 230
 231 /**
 232  * class_destroy - destroys a struct class structure
 233  * @cls: pointer to the struct class that is to be destroyed
 234  *
 235  * Note, the pointer to be destroyed must have been created with a call
 236  * to class_create().
 237  */
 238 void class_destroy(struct class *cls)
 239 {
 240         if ((cls == NULL) || (IS_ERR(cls)))
 241                 return;
 242
 243         class_unregister(cls);
 244 }
 245
 246 #ifdef CONFIG_SYSFS_DEPRECATED
 247 char *make_class_name(const char *name, struct kobject *kobj)
 248 {
 249         char *class_name;
 250         int size;
 251
 252         size = strlen(name) + strlen(kobject_name(kobj)) + 2;
 253
 254         class_name = kmalloc(size, GFP_KERNEL);
 255         if (!class_name)
 256                 return NULL;
 257
 258         strcpy(class_name, name);
 259         strcat(class_name, ":");
 260         strcat(class_name, kobject_name(kobj));
 261         return class_name;
 262 }
 263 #endif
 264
 265 /**
 266  * class_for_each_device - device iterator
 267  * @class: the class we're iterating
 268  * @start: the device to start with in the list, if any.
 269  * @data: data for the callback
 270  * @fn: function to be called for each device
 271  *
 272  * Iterate over @class's list of devices, and call @fn for each,
 273  * passing it @data.  If @start is set, the list iteration will start
 274  * there, otherwise if it is NULL, the iteration starts at the
 275  * beginning of the list.
 276  *
 277  * We check the return of @fn each time. If it returns anything
 278  * other than 0, we break out and return that value.
 279  *
 280  * Note, we hold class->sem in this function, so it can not be
 281  * re-acquired in @fn, otherwise it will self-deadlocking. For
 282  * example, calls to add or remove class members would be verboten.
 283  */
 284 int class_for_each_device(struct class *class, struct device *start,
 285                           void *data, int (*fn)(struct device *, void *))
 286 {
 287         struct device *dev;
 288         int error = 0;
 289
 290         if (!class)
 291                 return -EINVAL;
 292         down(&class->p->sem);
 293         list_for_each_entry(dev, &class->p->class_devices, node) {
 294                 if (start) {
 295                         if (start == dev)
 296                                 start = NULL;
 297                         continue;
 298                 }
 299                 dev = get_device(dev);
 300                 error = fn(dev, data);
 301                 put_device(dev);
 302                 if (error)
 303                         break;
 304         }
 305         up(&class->p->sem);
 306
 307         return error;
 308 }
 309 EXPORT_SYMBOL_GPL(class_for_each_device);
 310
 311 /**
 312  * class_find_device - device iterator for locating a particular device
 313  * @class: the class we're iterating
 314  * @start: Device to begin with
 315  * @data: data for the match function
 316  * @match: function to check device
 317  *
 318  * This is similar to the class_for_each_dev() function above, but it
 319  * returns a reference to a device that is 'found' for later use, as
 320  * determined by the @match callback.
 321  *
 322  * The callback should return 0 if the device doesn't match and non-zero
 323  * if it does.  If the callback returns non-zero, this function will
 324  * return to the caller and not iterate over any more devices.
 325  *
 326  * Note, you will need to drop the reference with put_device() after use.
 327  *
 328  * We hold class->sem in this function, so it can not be
 329  * re-acquired in @match, otherwise it will self-deadlocking. For
 330  * example, calls to add or remove class members would be verboten.
 331  */
 332 struct device *class_find_device(struct class *class, struct device *start,
 333                                  void *data,
 334                                  int (*match)(struct device *, void *))
 335 {
 336         struct device *dev;
 337         int found = 0;
 338
 339         if (!class)
 340                 return NULL;
 341
 342         down(&class->p->sem);
 343         list_for_each_entry(dev, &class->p->class_devices, node) {
 344                 if (start) {
 345                         if (start == dev)
 346                                 start = NULL;
 347                         continue;
 348                 }
 349                 dev = get_device(dev);
 350                 if (match(dev, data)) {
 351                         found = 1;
 352                         break;
 353                 } else
 354                         put_device(dev);
 355         }
 356         up(&class->p->sem);
 357
 358         return found ? dev : NULL;
 359 }
 360 EXPORT_SYMBOL_GPL(class_find_device);
 361
 362 int class_interface_register(struct class_interface *class_intf)
 363 {
 364         struct class *parent;
 365         struct device *dev;
 366
 367         if (!class_intf || !class_intf->class)
 368                 return -ENODEV;
 369
 370         parent = class_get(class_intf->class);
 371         if (!parent)
 372                 return -EINVAL;
 373
 374         down(&parent->p->sem);
 375         list_add_tail(&class_intf->node, &parent->p->class_interfaces);
 376         if (class_intf->add_dev) {
 377                 list_for_each_entry(dev, &parent->p->class_devices, node)
 378                         class_intf->add_dev(dev, class_intf);
 379         }
 380         up(&parent->p->sem);
 381
 382         return 0;
 383 }
 384
 385 void class_interface_unregister(struct class_interface *class_intf)
 386 {
 387         struct class *parent = class_intf->class;
 388         struct device *dev;
 389
 390         if (!parent)
 391                 return;
 392
 393         down(&parent->p->sem);
 394         list_del_init(&class_intf->node);
 395         if (class_intf->remove_dev) {
 396                 list_for_each_entry(dev, &parent->p->class_devices, node)
 397                         class_intf->remove_dev(dev, class_intf);
 398         }
 399         up(&parent->p->sem);
 400
 401         class_put(parent);
 402 }
 403
 404 int __init classes_init(void)
 405 {
 406         class_kset = kset_create_and_add("class", NULL, NULL);
 407         if (!class_kset)
 408                 return -ENOMEM;
 409         return 0;
 410 }
 411
 412 EXPORT_SYMBOL_GPL(class_create_file);
 413 EXPORT_SYMBOL_GPL(class_remove_file);
 414 EXPORT_SYMBOL_GPL(class_register);
 415 EXPORT_SYMBOL_GPL(class_unregister);
 416 EXPORT_SYMBOL_GPL(class_create);
 417 EXPORT_SYMBOL_GPL(class_destroy);
 418
 419 EXPORT_SYMBOL_GPL(class_interface_register);
 420 EXPORT_SYMBOL_GPL(class_interface_unregister);