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