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 #define to_class(obj) container_of(obj, struct class, subsys.kobj)
  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 *dc = to_class(kobj);
  31         ssize_t ret = -EIO;
  32
  33         if (class_attr->show)
  34                 ret = class_attr->show(dc, 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 *dc = to_class(kobj);
  43         ssize_t ret = -EIO;
  44
  45         if (class_attr->store)
  46                 ret = class_attr->store(dc, buf, count);
  47         return ret;
  48 }
  49
  50 static void class_release(struct kobject *kobj)
  51 {
  52         struct class *class = to_class(kobj);
  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->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->subsys.kobj, &attr->attr);
  91 }
  92
  93 static struct class *class_get(struct class *cls)
  94 {
  95         if (cls)
  96                 return container_of(kset_get(&cls->subsys),
  97                                     struct class, subsys);
  98         return NULL;
  99 }
 100
 101 static void class_put(struct class *cls)
 102 {
 103         if (cls)
 104                 kset_put(&cls->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         int error;
 140
 141         pr_debug("device class '%s': registering\n", cls->name);
 142
 143         INIT_LIST_HEAD(&cls->devices);
 144         INIT_LIST_HEAD(&cls->interfaces);
 145         kset_init(&cls->class_dirs);
 146         init_MUTEX(&cls->sem);
 147         error = kobject_set_name(&cls->subsys.kobj, "%s", cls->name);
 148         if (error)
 149                 return error;
 150
 151         /* set the default /sys/dev directory for devices of this class */
 152         if (!cls->dev_kobj)
 153                 cls->dev_kobj = sysfs_dev_char_kobj;
 154
 155 #if defined(CONFIG_SYSFS_DEPRECATED) && defined(CONFIG_BLOCK)
 156         /* let the block class directory show up in the root of sysfs */
 157         if (cls != &block_class)
 158                 cls->subsys.kobj.kset = class_kset;
 159 #else
 160         cls->subsys.kobj.kset = class_kset;
 161 #endif
 162         cls->subsys.kobj.ktype = &class_ktype;
 163
 164         error = kset_register(&cls->subsys);
 165         if (!error) {
 166                 error = add_class_attrs(class_get(cls));
 167                 class_put(cls);
 168         }
 169         return error;
 170 }
 171
 172 void class_unregister(struct class *cls)
 173 {
 174         pr_debug("device class '%s': unregistering\n", cls->name);
 175         remove_class_attrs(cls);
 176         kset_unregister(&cls->subsys);
 177 }
 178
 179 static void class_create_release(struct class *cls)
 180 {
 181         pr_debug("%s called for %s\n", __func__, cls->name);
 182         kfree(cls);
 183 }
 184
 185 /**
 186  * class_create - create a struct class structure
 187  * @owner: pointer to the module that is to "own" this struct class
 188  * @name: pointer to a string for the name of this class.
 189  *
 190  * This is used to create a struct class pointer that can then be used
 191  * in calls to device_create().
 192  *
 193  * Note, the pointer created here is to be destroyed when finished by
 194  * making a call to class_destroy().
 195  */
 196 struct class *class_create(struct module *owner, const char *name)
 197 {
 198         struct class *cls;
 199         int retval;
 200
 201         cls = kzalloc(sizeof(*cls), GFP_KERNEL);
 202         if (!cls) {
 203                 retval = -ENOMEM;
 204                 goto error;
 205         }
 206
 207         cls->name = name;
 208         cls->owner = owner;
 209         cls->class_release = class_create_release;
 210
 211         retval = class_register(cls);
 212         if (retval)
 213                 goto error;
 214
 215         return cls;
 216
 217 error:
 218         kfree(cls);
 219         return ERR_PTR(retval);
 220 }
 221
 222 /**
 223  * class_destroy - destroys a struct class structure
 224  * @cls: pointer to the struct class that is to be destroyed
 225  *
 226  * Note, the pointer to be destroyed must have been created with a call
 227  * to class_create().
 228  */
 229 void class_destroy(struct class *cls)
 230 {
 231         if ((cls == NULL) || (IS_ERR(cls)))
 232                 return;
 233
 234         class_unregister(cls);
 235 }
 236
 237 #ifdef CONFIG_SYSFS_DEPRECATED
 238 char *make_class_name(const char *name, struct kobject *kobj)
 239 {
 240         char *class_name;
 241         int size;
 242
 243         size = strlen(name) + strlen(kobject_name(kobj)) + 2;
 244
 245         class_name = kmalloc(size, GFP_KERNEL);
 246         if (!class_name)
 247                 return NULL;
 248
 249         strcpy(class_name, name);
 250         strcat(class_name, ":");
 251         strcat(class_name, kobject_name(kobj));
 252         return class_name;
 253 }
 254 #endif
 255
 256 /**
 257  * class_for_each_device - device iterator
 258  * @class: the class we're iterating
 259  * @data: data for the callback
 260  * @fn: function to be called for each device
 261  *
 262  * Iterate over @class's list of devices, and call @fn for each,
 263  * passing it @data.
 264  *
 265  * We check the return of @fn each time. If it returns anything
 266  * other than 0, we break out and return that value.
 267  *
 268  * Note, we hold class->sem in this function, so it can not be
 269  * re-acquired in @fn, otherwise it will self-deadlocking. For
 270  * example, calls to add or remove class members would be verboten.
 271  */
 272 int class_for_each_device(struct class *class, void *data,
 273                            int (*fn)(struct device *, void *))
 274 {
 275         struct device *dev;
 276         int error = 0;
 277
 278         if (!class)
 279                 return -EINVAL;
 280         down(&class->sem);
 281         list_for_each_entry(dev, &class->devices, node) {
 282                 dev = get_device(dev);
 283                 if (dev) {
 284                         error = fn(dev, data);
 285                         put_device(dev);
 286                 } else
 287                         error = -ENODEV;
 288                 if (error)
 289                         break;
 290         }
 291         up(&class->sem);
 292
 293         return error;
 294 }
 295 EXPORT_SYMBOL_GPL(class_for_each_device);
 296
 297 /**
 298  * class_find_device - device iterator for locating a particular device
 299  * @class: the class we're iterating
 300  * @data: data for the match function
 301  * @match: function to check device
 302  *
 303  * This is similar to the class_for_each_dev() function above, but it
 304  * returns a reference to a device that is 'found' for later use, as
 305  * determined by the @match callback.
 306  *
 307  * The callback should return 0 if the device doesn't match and non-zero
 308  * if it does.  If the callback returns non-zero, this function will
 309  * return to the caller and not iterate over any more devices.
 310  *
 311  * Note, you will need to drop the reference with put_device() after use.
 312  *
 313  * We hold class->sem in this function, so it can not be
 314  * re-acquired in @match, otherwise it will self-deadlocking. For
 315  * example, calls to add or remove class members would be verboten.
 316  */
 317 struct device *class_find_device(struct class *class, void *data,
 318                                    int (*match)(struct device *, void *))
 319 {
 320         struct device *dev;
 321         int found = 0;
 322
 323         if (!class)
 324                 return NULL;
 325
 326         down(&class->sem);
 327         list_for_each_entry(dev, &class->devices, node) {
 328                 dev = get_device(dev);
 329                 if (dev) {
 330                         if (match(dev, data)) {
 331                                 found = 1;
 332                                 break;
 333                         } else
 334                                 put_device(dev);
 335                 } else
 336                         break;
 337         }
 338         up(&class->sem);
 339
 340         return found ? dev : NULL;
 341 }
 342 EXPORT_SYMBOL_GPL(class_find_device);
 343
 344 int class_interface_register(struct class_interface *class_intf)
 345 {
 346         struct class *parent;
 347         struct device *dev;
 348
 349         if (!class_intf || !class_intf->class)
 350                 return -ENODEV;
 351
 352         parent = class_get(class_intf->class);
 353         if (!parent)
 354                 return -EINVAL;
 355
 356         down(&parent->sem);
 357         list_add_tail(&class_intf->node, &parent->interfaces);
 358         if (class_intf->add_dev) {
 359                 list_for_each_entry(dev, &parent->devices, node)
 360                         class_intf->add_dev(dev, class_intf);
 361         }
 362         up(&parent->sem);
 363
 364         return 0;
 365 }
 366
 367 void class_interface_unregister(struct class_interface *class_intf)
 368 {
 369         struct class *parent = class_intf->class;
 370         struct device *dev;
 371
 372         if (!parent)
 373                 return;
 374
 375         down(&parent->sem);
 376         list_del_init(&class_intf->node);
 377         if (class_intf->remove_dev) {
 378                 list_for_each_entry(dev, &parent->devices, node)
 379                         class_intf->remove_dev(dev, class_intf);
 380         }
 381         up(&parent->sem);
 382
 383         class_put(parent);
 384 }
 385
 386 int __init classes_init(void)
 387 {
 388         class_kset = kset_create_and_add("class", NULL, NULL);
 389         if (!class_kset)
 390                 return -ENOMEM;
 391         return 0;
 392 }
 393
 394 EXPORT_SYMBOL_GPL(class_create_file);
 395 EXPORT_SYMBOL_GPL(class_remove_file);
 396 EXPORT_SYMBOL_GPL(class_register);
 397 EXPORT_SYMBOL_GPL(class_unregister);
 398 EXPORT_SYMBOL_GPL(class_create);
 399 EXPORT_SYMBOL_GPL(class_destroy);
 400
 401 EXPORT_SYMBOL_GPL(class_interface_register);
 402 EXPORT_SYMBOL_GPL(class_interface_unregister);