drivers/base/core.c

   1 /*
   2  * drivers/base/core.c - core driver model code (device registration, etc)
   3  *
   4  * Copyright (c) 2002-3 Patrick Mochel
   5  * Copyright (c) 2002-3 Open Source Development Labs
   6  *
   7  * This file is released under the GPLv2
   8  *
   9  */
  10
  11 #include <linux/config.h>
  12 #include <linux/device.h>
  13 #include <linux/err.h>
  14 #include <linux/init.h>
  15 #include <linux/module.h>
  16 #include <linux/slab.h>
  17 #include <linux/string.h>
  18 #include <linux/kdev_t.h>
  19
  20 #include <asm/semaphore.h>
  21
  22 #include "base.h"
  23 #include "power/power.h"
  24
  25 int (*platform_notify)(struct device * dev) = NULL;
  26 int (*platform_notify_remove)(struct device * dev) = NULL;
  27
  28 /*
  29  * sysfs bindings for devices.
  30  */
  31
  32 #define to_dev(obj) container_of(obj, struct device, kobj)
  33 #define to_dev_attr(_attr) container_of(_attr, struct device_attribute, attr)
  34
  35 static ssize_t
  36 dev_attr_show(struct kobject * kobj, struct attribute * attr, char * buf)
  37 {
  38         struct device_attribute * dev_attr = to_dev_attr(attr);
  39         struct device * dev = to_dev(kobj);
  40         ssize_t ret = -EIO;
  41
  42         if (dev_attr->show)
  43                 ret = dev_attr->show(dev, dev_attr, buf);
  44         return ret;
  45 }
  46
  47 static ssize_t
  48 dev_attr_store(struct kobject * kobj, struct attribute * attr,
  49                const char * buf, size_t count)
  50 {
  51         struct device_attribute * dev_attr = to_dev_attr(attr);
  52         struct device * dev = to_dev(kobj);
  53         ssize_t ret = -EIO;
  54
  55         if (dev_attr->store)
  56                 ret = dev_attr->store(dev, dev_attr, buf, count);
  57         return ret;
  58 }
  59
  60 static struct sysfs_ops dev_sysfs_ops = {
  61         .show   = dev_attr_show,
  62         .store  = dev_attr_store,
  63 };
  64
  65
  66 /**
  67  *      device_release - free device structure.
  68  *      @kobj:  device's kobject.
  69  *
  70  *      This is called once the reference count for the object
  71  *      reaches 0. We forward the call to the device's release
  72  *      method, which should handle actually freeing the structure.
  73  */
  74 static void device_release(struct kobject * kobj)
  75 {
  76         struct device * dev = to_dev(kobj);
  77
  78         if (dev->release)
  79                 dev->release(dev);
  80         else {
  81                 printk(KERN_ERR "Device '%s' does not have a release() function, "
  82                         "it is broken and must be fixed.\n",
  83                         dev->bus_id);
  84                 WARN_ON(1);
  85         }
  86 }
  87
  88 static struct kobj_type ktype_device = {
  89         .release        = device_release,
  90         .sysfs_ops      = &dev_sysfs_ops,
  91 };
  92
  93
  94 static int dev_uevent_filter(struct kset *kset, struct kobject *kobj)
  95 {
  96         struct kobj_type *ktype = get_ktype(kobj);
  97
  98         if (ktype == &ktype_device) {
  99                 struct device *dev = to_dev(kobj);
 100                 if (dev->bus)
 101                         return 1;
 102                 if (dev->class)
 103                         return 1;
 104         }
 105         return 0;
 106 }
 107
 108 static const char *dev_uevent_name(struct kset *kset, struct kobject *kobj)
 109 {
 110         struct device *dev = to_dev(kobj);
 111
 112         if (dev->bus)
 113                 return dev->bus->name;
 114         if (dev->class)
 115                 return dev->class->name;
 116         return NULL;
 117 }
 118
 119 static int dev_uevent(struct kset *kset, struct kobject *kobj, char **envp,
 120                         int num_envp, char *buffer, int buffer_size)
 121 {
 122         struct device *dev = to_dev(kobj);
 123         int i = 0;
 124         int length = 0;
 125         int retval = 0;
 126
 127         /* add the major/minor if present */
 128         if (MAJOR(dev->devt)) {
 129                 add_uevent_var(envp, num_envp, &i,
 130                                buffer, buffer_size, &length,
 131                                "MAJOR=%u", MAJOR(dev->devt));
 132                 add_uevent_var(envp, num_envp, &i,
 133                                buffer, buffer_size, &length,
 134                                "MINOR=%u", MINOR(dev->devt));
 135         }
 136
 137         /* add bus name of physical device */
 138         if (dev->bus)
 139                 add_uevent_var(envp, num_envp, &i,
 140                                buffer, buffer_size, &length,
 141                                "PHYSDEVBUS=%s", dev->bus->name);
 142
 143         /* add driver name of physical device */
 144         if (dev->driver)
 145                 add_uevent_var(envp, num_envp, &i,
 146                                buffer, buffer_size, &length,
 147                                "PHYSDEVDRIVER=%s", dev->driver->name);
 148
 149         /* terminate, set to next free slot, shrink available space */
 150         envp[i] = NULL;
 151         envp = &envp[i];
 152         num_envp -= i;
 153         buffer = &buffer[length];
 154         buffer_size -= length;
 155
 156         if (dev->bus && dev->bus->uevent) {
 157                 /* have the bus specific function add its stuff */
 158                 retval = dev->bus->uevent(dev, envp, num_envp, buffer, buffer_size);
 159                         if (retval) {
 160                         pr_debug ("%s - uevent() returned %d\n",
 161                                   __FUNCTION__, retval);
 162                 }
 163         }
 164
 165         return retval;
 166 }
 167
 168 static struct kset_uevent_ops device_uevent_ops = {
 169         .filter =       dev_uevent_filter,
 170         .name =         dev_uevent_name,
 171         .uevent =       dev_uevent,
 172 };
 173
 174 static ssize_t store_uevent(struct device *dev, struct device_attribute *attr,
 175                             const char *buf, size_t count)
 176 {
 177         kobject_uevent(&dev->kobj, KOBJ_ADD);
 178         return count;
 179 }
 180
 181 static ssize_t show_dev(struct device *dev, struct device_attribute *attr,
 182                         char *buf)
 183 {
 184         return print_dev_t(buf, dev->devt);
 185 }
 186
 187 /*
 188  *      devices_subsys - structure to be registered with kobject core.
 189  */
 190
 191 decl_subsys(devices, &ktype_device, &device_uevent_ops);
 192
 193
 194 /**
 195  *      device_create_file - create sysfs attribute file for device.
 196  *      @dev:   device.
 197  *      @attr:  device attribute descriptor.
 198  */
 199
 200 int device_create_file(struct device * dev, struct device_attribute * attr)
 201 {
 202         int error = 0;
 203         if (get_device(dev)) {
 204                 error = sysfs_create_file(&dev->kobj, &attr->attr);
 205                 put_device(dev);
 206         }
 207         return error;
 208 }
 209
 210 /**
 211  *      device_remove_file - remove sysfs attribute file.
 212  *      @dev:   device.
 213  *      @attr:  device attribute descriptor.
 214  */
 215
 216 void device_remove_file(struct device * dev, struct device_attribute * attr)
 217 {
 218         if (get_device(dev)) {
 219                 sysfs_remove_file(&dev->kobj, &attr->attr);
 220                 put_device(dev);
 221         }
 222 }
 223
 224 static void klist_children_get(struct klist_node *n)
 225 {
 226         struct device *dev = container_of(n, struct device, knode_parent);
 227
 228         get_device(dev);
 229 }
 230
 231 static void klist_children_put(struct klist_node *n)
 232 {
 233         struct device *dev = container_of(n, struct device, knode_parent);
 234
 235         put_device(dev);
 236 }
 237
 238
 239 /**
 240  *      device_initialize - init device structure.
 241  *      @dev:   device.
 242  *
 243  *      This prepares the device for use by other layers,
 244  *      including adding it to the device hierarchy.
 245  *      It is the first half of device_register(), if called by
 246  *      that, though it can also be called separately, so one
 247  *      may use @dev's fields (e.g. the refcount).
 248  */
 249
 250 void device_initialize(struct device *dev)
 251 {
 252         kobj_set_kset_s(dev, devices_subsys);
 253         kobject_init(&dev->kobj);
 254         klist_init(&dev->klist_children, klist_children_get,
 255                    klist_children_put);
 256         INIT_LIST_HEAD(&dev->dma_pools);
 257         INIT_LIST_HEAD(&dev->node);
 258         init_MUTEX(&dev->sem);
 259         device_init_wakeup(dev, 0);
 260 }
 261
 262 /**
 263  *      device_add - add device to device hierarchy.
 264  *      @dev:   device.
 265  *
 266  *      This is part 2 of device_register(), though may be called
 267  *      separately _iff_ device_initialize() has been called separately.
 268  *
 269  *      This adds it to the kobject hierarchy via kobject_add(), adds it
 270  *      to the global and sibling lists for the device, then
 271  *      adds it to the other relevant subsystems of the driver model.
 272  */
 273 int device_add(struct device *dev)
 274 {
 275         struct device *parent = NULL;
 276         int error = -EINVAL;
 277
 278         dev = get_device(dev);
 279         if (!dev || !strlen(dev->bus_id))
 280                 goto Error;
 281
 282         parent = get_device(dev->parent);
 283
 284         pr_debug("DEV: registering device: ID = '%s'\n", dev->bus_id);
 285
 286         /* first, register with generic layer. */
 287         kobject_set_name(&dev->kobj, "%s", dev->bus_id);
 288         if (parent)
 289                 dev->kobj.parent = &parent->kobj;
 290
 291         if ((error = kobject_add(&dev->kobj)))
 292                 goto Error;
 293
 294         dev->uevent_attr.attr.name = "uevent";
 295         dev->uevent_attr.attr.mode = S_IWUSR;
 296         if (dev->driver)
 297                 dev->uevent_attr.attr.owner = dev->driver->owner;
 298         dev->uevent_attr.store = store_uevent;
 299         device_create_file(dev, &dev->uevent_attr);
 300
 301         if (MAJOR(dev->devt)) {
 302                 struct device_attribute *attr;
 303                 attr = kzalloc(sizeof(*attr), GFP_KERNEL);
 304                 if (!attr) {
 305                         error = -ENOMEM;
 306                         goto PMError;
 307                 }
 308                 attr->attr.name = "dev";
 309                 attr->attr.mode = S_IRUGO;
 310                 if (dev->driver)
 311                         attr->attr.owner = dev->driver->owner;
 312                 attr->show = show_dev;
 313                 error = device_create_file(dev, attr);
 314                 if (error) {
 315                         kfree(attr);
 316                         goto attrError;
 317                 }
 318
 319                 dev->devt_attr = attr;
 320         }
 321
 322         if (dev->class) {
 323                 sysfs_create_link(&dev->kobj, &dev->class->subsys.kset.kobj,
 324                                   "subsystem");
 325                 sysfs_create_link(&dev->class->subsys.kset.kobj, &dev->kobj,
 326                                   dev->bus_id);
 327         }
 328
 329         if ((error = device_pm_add(dev)))
 330                 goto PMError;
 331         if ((error = bus_add_device(dev)))
 332                 goto BusError;
 333         kobject_uevent(&dev->kobj, KOBJ_ADD);
 334         bus_attach_device(dev);
 335         if (parent)
 336                 klist_add_tail(&dev->knode_parent, &parent->klist_children);
 337
 338         /* notify platform of device entry */
 339         if (platform_notify)
 340                 platform_notify(dev);
 341  Done:
 342         put_device(dev);
 343         return error;
 344  BusError:
 345         device_pm_remove(dev);
 346  PMError:
 347         if (dev->devt_attr) {
 348                 device_remove_file(dev, dev->devt_attr);
 349                 kfree(dev->devt_attr);
 350         }
 351  attrError:
 352         kobject_uevent(&dev->kobj, KOBJ_REMOVE);
 353         kobject_del(&dev->kobj);
 354  Error:
 355         if (parent)
 356                 put_device(parent);
 357         goto Done;
 358 }
 359
 360
 361 /**
 362  *      device_register - register a device with the system.
 363  *      @dev:   pointer to the device structure
 364  *
 365  *      This happens in two clean steps - initialize the device
 366  *      and add it to the system. The two steps can be called
 367  *      separately, but this is the easiest and most common.
 368  *      I.e. you should only call the two helpers separately if
 369  *      have a clearly defined need to use and refcount the device
 370  *      before it is added to the hierarchy.
 371  */
 372
 373 int device_register(struct device *dev)
 374 {
 375         device_initialize(dev);
 376         return device_add(dev);
 377 }
 378
 379
 380 /**
 381  *      get_device - increment reference count for device.
 382  *      @dev:   device.
 383  *
 384  *      This simply forwards the call to kobject_get(), though
 385  *      we do take care to provide for the case that we get a NULL
 386  *      pointer passed in.
 387  */
 388
 389 struct device * get_device(struct device * dev)
 390 {
 391         return dev ? to_dev(kobject_get(&dev->kobj)) : NULL;
 392 }
 393
 394
 395 /**
 396  *      put_device - decrement reference count.
 397  *      @dev:   device in question.
 398  */
 399 void put_device(struct device * dev)
 400 {
 401         if (dev)
 402                 kobject_put(&dev->kobj);
 403 }
 404
 405
 406 /**
 407  *      device_del - delete device from system.
 408  *      @dev:   device.
 409  *
 410  *      This is the first part of the device unregistration
 411  *      sequence. This removes the device from the lists we control
 412  *      from here, has it removed from the other driver model
 413  *      subsystems it was added to in device_add(), and removes it
 414  *      from the kobject hierarchy.
 415  *
 416  *      NOTE: this should be called manually _iff_ device_add() was
 417  *      also called manually.
 418  */
 419
 420 void device_del(struct device * dev)
 421 {
 422         struct device * parent = dev->parent;
 423
 424         if (parent)
 425                 klist_del(&dev->knode_parent);
 426         if (dev->devt_attr)
 427                 device_remove_file(dev, dev->devt_attr);
 428         if (dev->class) {
 429                 sysfs_remove_link(&dev->kobj, "subsystem");
 430                 sysfs_remove_link(&dev->class->subsys.kset.kobj, dev->bus_id);
 431         }
 432         device_remove_file(dev, &dev->uevent_attr);
 433
 434         /* Notify the platform of the removal, in case they
 435          * need to do anything...
 436          */
 437         if (platform_notify_remove)
 438                 platform_notify_remove(dev);
 439         bus_remove_device(dev);
 440         device_pm_remove(dev);
 441         kobject_uevent(&dev->kobj, KOBJ_REMOVE);
 442         kobject_del(&dev->kobj);
 443         if (parent)
 444                 put_device(parent);
 445 }
 446
 447 /**
 448  *      device_unregister - unregister device from system.
 449  *      @dev:   device going away.
 450  *
 451  *      We do this in two parts, like we do device_register(). First,
 452  *      we remove it from all the subsystems with device_del(), then
 453  *      we decrement the reference count via put_device(). If that
 454  *      is the final reference count, the device will be cleaned up
 455  *      via device_release() above. Otherwise, the structure will
 456  *      stick around until the final reference to the device is dropped.
 457  */
 458 void device_unregister(struct device * dev)
 459 {
 460         pr_debug("DEV: Unregistering device. ID = '%s'\n", dev->bus_id);
 461         device_del(dev);
 462         put_device(dev);
 463 }
 464
 465
 466 static struct device * next_device(struct klist_iter * i)
 467 {
 468         struct klist_node * n = klist_next(i);
 469         return n ? container_of(n, struct device, knode_parent) : NULL;
 470 }
 471
 472 /**
 473  *      device_for_each_child - device child iterator.
 474  *      @parent: parent struct device.
 475  *      @data:  data for the callback.
 476  *      @fn:    function to be called for each device.
 477  *
 478  *      Iterate over @parent's child devices, and call @fn for each,
 479  *      passing it @data.
 480  *
 481  *      We check the return of @fn each time. If it returns anything
 482  *      other than 0, we break out and return that value.
 483  */
 484 int device_for_each_child(struct device * parent, void * data,
 485                      int (*fn)(struct device *, void *))
 486 {
 487         struct klist_iter i;
 488         struct device * child;
 489         int error = 0;
 490
 491         klist_iter_init(&parent->klist_children, &i);
 492         while ((child = next_device(&i)) && !error)
 493                 error = fn(child, data);
 494         klist_iter_exit(&i);
 495         return error;
 496 }
 497
 498 int __init devices_init(void)
 499 {
 500         return subsystem_register(&devices_subsys);
 501 }
 502
 503 EXPORT_SYMBOL_GPL(device_for_each_child);
 504
 505 EXPORT_SYMBOL_GPL(device_initialize);
 506 EXPORT_SYMBOL_GPL(device_add);
 507 EXPORT_SYMBOL_GPL(device_register);
 508
 509 EXPORT_SYMBOL_GPL(device_del);
 510 EXPORT_SYMBOL_GPL(device_unregister);
 511 EXPORT_SYMBOL_GPL(get_device);
 512 EXPORT_SYMBOL_GPL(put_device);
 513
 514 EXPORT_SYMBOL_GPL(device_create_file);
 515 EXPORT_SYMBOL_GPL(device_remove_file);
 516
 517
 518 static void device_create_release(struct device *dev)
 519 {
 520         pr_debug("%s called for %s\n", __FUNCTION__, dev->bus_id);
 521         kfree(dev);
 522 }
 523
 524 /**
 525  * device_create - creates a device and registers it with sysfs
 526  * @cs: pointer to the struct class that this device should be registered to.
 527  * @parent: pointer to the parent struct device of this new device, if any.
 528  * @dev: the dev_t for the char device to be added.
 529  * @fmt: string for the class device's name
 530  *
 531  * This function can be used by char device classes.  A struct
 532  * device will be created in sysfs, registered to the specified
 533  * class.
 534  * A "dev" file will be created, showing the dev_t for the device, if
 535  * the dev_t is not 0,0.
 536  * If a pointer to a parent struct device is passed in, the newly
 537  * created struct device will be a child of that device in sysfs.  The
 538  * pointer to the struct device will be returned from the call.  Any
 539  * further sysfs files that might be required can be created using this
 540  * pointer.
 541  *
 542  * Note: the struct class passed to this function must have previously
 543  * been created with a call to class_create().
 544  */
 545 struct device *device_create(struct class *class, struct device *parent,
 546                              dev_t devt, char *fmt, ...)
 547 {
 548         va_list args;
 549         struct device *dev = NULL;
 550         int retval = -ENODEV;
 551
 552         if (class == NULL || IS_ERR(class))
 553                 goto error;
 554         if (parent == NULL) {
 555                 printk(KERN_WARNING "%s does not work yet for NULL parents\n", __FUNCTION__);
 556                 goto error;
 557         }
 558
 559         dev = kzalloc(sizeof(*dev), GFP_KERNEL);
 560         if (!dev) {
 561                 retval = -ENOMEM;
 562                 goto error;
 563         }
 564
 565         dev->devt = devt;
 566         dev->class = class;
 567         dev->parent = parent;
 568         dev->release = device_create_release;
 569
 570         va_start(args, fmt);
 571         vsnprintf(dev->bus_id, BUS_ID_SIZE, fmt, args);
 572         va_end(args);
 573         retval = device_register(dev);
 574         if (retval)
 575                 goto error;
 576
 577         /* tie the class to the device */
 578         down(&class->sem);
 579         list_add_tail(&dev->node, &class->devices);
 580         up(&class->sem);
 581
 582         return dev;
 583
 584 error:
 585         kfree(dev);
 586         return ERR_PTR(retval);
 587 }
 588 EXPORT_SYMBOL_GPL(device_create);
 589
 590 /**
 591  * device_destroy - removes a device that was created with device_create()
 592  * @class: the pointer to the struct class that this device was registered * with.
 593  * @dev: the dev_t of the device that was previously registered.
 594  *
 595  * This call unregisters and cleans up a class device that was created with a
 596  * call to class_device_create()
 597  */
 598 void device_destroy(struct class *class, dev_t devt)
 599 {
 600         struct device *dev = NULL;
 601         struct device *dev_tmp;
 602
 603         down(&class->sem);
 604         list_for_each_entry(dev_tmp, &class->devices, node) {
 605                 if (dev_tmp->devt == devt) {
 606                         dev = dev_tmp;
 607                         break;
 608                 }
 609         }
 610         up(&class->sem);
 611
 612         if (dev) {
 613                 list_del_init(&dev->node);
 614                 device_unregister(dev);
 615         }
 616 }
 617 EXPORT_SYMBOL_GPL(device_destroy);