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