include/linux/device.h

   1 /*
   2  * device.h - generic, centralized driver model
   3  *
   4  * Copyright (c) 2001-2003 Patrick Mochel <mochel@osdl.org>
   5  * Copyright (c) 2004-2007 Greg Kroah-Hartman <gregkh@suse.de>
   6  *
   7  * This file is released under the GPLv2
   8  *
   9  * See Documentation/driver-model/ for more information.
  10  */
  11
  12 #ifndef _DEVICE_H_
  13 #define _DEVICE_H_
  14
  15 #include <linux/ioport.h>
  16 #include <linux/kobject.h>
  17 #include <linux/klist.h>
  18 #include <linux/list.h>
  19 #include <linux/compiler.h>
  20 #include <linux/types.h>
  21 #include <linux/module.h>
  22 #include <linux/pm.h>
  23 #include <asm/semaphore.h>
  24 #include <asm/atomic.h>
  25 #include <asm/device.h>
  26
  27 #define DEVICE_NAME_SIZE        50
  28 /* DEVICE_NAME_HALF is really less than half to accommodate slop */
  29 #define DEVICE_NAME_HALF        __stringify(20)
  30 #define DEVICE_ID_SIZE          32
  31 #define BUS_ID_SIZE             KOBJ_NAME_LEN
  32
  33
  34 struct device;
  35 struct device_driver;
  36 struct driver_private;
  37 struct class;
  38 struct class_device;
  39 struct bus_type;
  40 struct bus_type_private;
  41
  42 struct bus_attribute {
  43         struct attribute        attr;
  44         ssize_t (*show)(struct bus_type *bus, char *buf);
  45         ssize_t (*store)(struct bus_type *bus, const char *buf, size_t count);
  46 };
  47
  48 #define BUS_ATTR(_name, _mode, _show, _store)   \
  49 struct bus_attribute bus_attr_##_name = __ATTR(_name, _mode, _show, _store)
  50
  51 extern int __must_check bus_create_file(struct bus_type *,
  52                                         struct bus_attribute *);
  53 extern void bus_remove_file(struct bus_type *, struct bus_attribute *);
  54
  55 struct bus_type {
  56         const char              *name;
  57         struct bus_attribute    *bus_attrs;
  58         struct device_attribute *dev_attrs;
  59         struct driver_attribute *drv_attrs;
  60
  61         int (*match)(struct device *dev, struct device_driver *drv);
  62         int (*uevent)(struct device *dev, struct kobj_uevent_env *env);
  63         int (*probe)(struct device *dev);
  64         int (*remove)(struct device *dev);
  65         void (*shutdown)(struct device *dev);
  66
  67         int (*suspend)(struct device *dev, pm_message_t state);
  68         int (*suspend_late)(struct device *dev, pm_message_t state);
  69         int (*resume_early)(struct device *dev);
  70         int (*resume)(struct device *dev);
  71
  72         struct bus_type_private *p;
  73 };
  74
  75 extern int __must_check bus_register(struct bus_type *bus);
  76 extern void bus_unregister(struct bus_type *bus);
  77
  78 extern int __must_check bus_rescan_devices(struct bus_type *bus);
  79
  80 /* iterator helpers for buses */
  81
  82 int bus_for_each_dev(struct bus_type *bus, struct device *start, void *data,
  83                      int (*fn)(struct device *dev, void *data));
  84 struct device *bus_find_device(struct bus_type *bus, struct device *start,
  85                                void *data,
  86                                int (*match)(struct device *dev, void *data));
  87 struct device *bus_find_device_by_name(struct bus_type *bus,
  88                                        struct device *start,
  89                                        const char *name);
  90
  91 int __must_check bus_for_each_drv(struct bus_type *bus,
  92                                   struct device_driver *start, void *data,
  93                                   int (*fn)(struct device_driver *, void *));
  94
  95 /*
  96  * Bus notifiers: Get notified of addition/removal of devices
  97  * and binding/unbinding of drivers to devices.
  98  * In the long run, it should be a replacement for the platform
  99  * notify hooks.
 100  */
 101 struct notifier_block;
 102
 103 extern int bus_register_notifier(struct bus_type *bus,
 104                                  struct notifier_block *nb);
 105 extern int bus_unregister_notifier(struct bus_type *bus,
 106                                    struct notifier_block *nb);
 107
 108 /* All 4 notifers below get called with the target struct device *
 109  * as an argument. Note that those functions are likely to be called
 110  * with the device semaphore held in the core, so be careful.
 111  */
 112 #define BUS_NOTIFY_ADD_DEVICE           0x00000001 /* device added */
 113 #define BUS_NOTIFY_DEL_DEVICE           0x00000002 /* device removed */
 114 #define BUS_NOTIFY_BOUND_DRIVER         0x00000003 /* driver bound to device */
 115 #define BUS_NOTIFY_UNBIND_DRIVER        0x00000004 /* driver about to be
 116                                                       unbound */
 117
 118 extern struct kset *bus_get_kset(struct bus_type *bus);
 119 extern struct klist *bus_get_device_klist(struct bus_type *bus);
 120
 121 struct device_driver {
 122         const char              *name;
 123         struct bus_type         *bus;
 124
 125         struct module           *owner;
 126         const char              *mod_name;      /* used for built-in modules */
 127
 128         int (*probe) (struct device *dev);
 129         int (*remove) (struct device *dev);
 130         void (*shutdown) (struct device *dev);
 131         int (*suspend) (struct device *dev, pm_message_t state);
 132         int (*resume) (struct device *dev);
 133         struct attribute_group **groups;
 134
 135         struct driver_private *p;
 136 };
 137
 138
 139 extern int __must_check driver_register(struct device_driver *drv);
 140 extern void driver_unregister(struct device_driver *drv);
 141
 142 extern struct device_driver *get_driver(struct device_driver *drv);
 143 extern void put_driver(struct device_driver *drv);
 144 extern struct device_driver *driver_find(const char *name,
 145                                          struct bus_type *bus);
 146 extern int driver_probe_done(void);
 147
 148 /* sysfs interface for exporting driver attributes */
 149
 150 struct driver_attribute {
 151         struct attribute attr;
 152         ssize_t (*show)(struct device_driver *driver, char *buf);
 153         ssize_t (*store)(struct device_driver *driver, const char *buf,
 154                          size_t count);
 155 };
 156
 157 #define DRIVER_ATTR(_name, _mode, _show, _store)        \
 158 struct driver_attribute driver_attr_##_name =           \
 159         __ATTR(_name, _mode, _show, _store)
 160
 161 extern int __must_check driver_create_file(struct device_driver *driver,
 162                                            struct driver_attribute *attr);
 163 extern void driver_remove_file(struct device_driver *driver,
 164                                struct driver_attribute *attr);
 165
 166 extern int __must_check driver_add_kobj(struct device_driver *drv,
 167                                         struct kobject *kobj,
 168                                         const char *fmt, ...);
 169
 170 extern int __must_check driver_for_each_device(struct device_driver *drv,
 171                                                struct device *start,
 172                                                void *data,
 173                                                int (*fn)(struct device *dev,
 174                                                          void *));
 175 struct device *driver_find_device(struct device_driver *drv,
 176                                   struct device *start, void *data,
 177                                   int (*match)(struct device *dev, void *data));
 178
 179 /*
 180  * device classes
 181  */
 182 struct class {
 183         const char              *name;
 184         struct module           *owner;
 185
 186         struct kset             subsys;
 187         struct list_head        children;
 188         struct list_head        devices;
 189         struct list_head        interfaces;
 190         struct kset             class_dirs;
 191         struct semaphore        sem; /* locks children, devices, interfaces */
 192         struct class_attribute          *class_attrs;
 193         struct class_device_attribute   *class_dev_attrs;
 194         struct device_attribute         *dev_attrs;
 195
 196         int (*uevent)(struct class_device *dev, struct kobj_uevent_env *env);
 197         int (*dev_uevent)(struct device *dev, struct kobj_uevent_env *env);
 198
 199         void (*release)(struct class_device *dev);
 200         void (*class_release)(struct class *class);
 201         void (*dev_release)(struct device *dev);
 202
 203         int (*suspend)(struct device *dev, pm_message_t state);
 204         int (*resume)(struct device *dev);
 205 };
 206
 207 extern int __must_check class_register(struct class *class);
 208 extern void class_unregister(struct class *class);
 209 extern int class_for_each_device(struct class *class, void *data,
 210                                  int (*fn)(struct device *dev, void *data));
 211 extern struct device *class_find_device(struct class *class, void *data,
 212                                         int (*match)(struct device *, void *));
 213 extern struct class_device *class_find_child(struct class *class, void *data,
 214                                    int (*match)(struct class_device *, void *));
 215
 216
 217 struct class_attribute {
 218         struct attribute attr;
 219         ssize_t (*show)(struct class *class, char *buf);
 220         ssize_t (*store)(struct class *class, const char *buf, size_t count);
 221 };
 222
 223 #define CLASS_ATTR(_name, _mode, _show, _store)                 \
 224 struct class_attribute class_attr_##_name = __ATTR(_name, _mode, _show, _store)
 225
 226 extern int __must_check class_create_file(struct class *class,
 227                                           const struct class_attribute *attr);
 228 extern void class_remove_file(struct class *class,
 229                               const struct class_attribute *attr);
 230
 231 struct class_device_attribute {
 232         struct attribute attr;
 233         ssize_t (*show)(struct class_device *, char *buf);
 234         ssize_t (*store)(struct class_device *, const char *buf, size_t count);
 235 };
 236
 237 #define CLASS_DEVICE_ATTR(_name, _mode, _show, _store)          \
 238 struct class_device_attribute class_device_attr_##_name =       \
 239         __ATTR(_name, _mode, _show, _store)
 240
 241 extern int __must_check class_device_create_file(struct class_device *,
 242                                     const struct class_device_attribute *);
 243
 244 /**
 245  * struct class_device - class devices
 246  * @class: pointer to the parent class for this class device.  This is required.
 247  * @devt: for internal use by the driver core only.
 248  * @node: for internal use by the driver core only.
 249  * @kobj: for internal use by the driver core only.
 250  * @groups: optional additional groups to be created
 251  * @dev: if set, a symlink to the struct device is created in the sysfs
 252  * directory for this struct class device.
 253  * @class_data: pointer to whatever you want to store here for this struct
 254  * class_device.  Use class_get_devdata() and class_set_devdata() to get and
 255  * set this pointer.
 256  * @parent: pointer to a struct class_device that is the parent of this struct
 257  * class_device.  If NULL, this class_device will show up at the root of the
 258  * struct class in sysfs (which is probably what you want to have happen.)
 259  * @release: pointer to a release function for this struct class_device.  If
 260  * set, this will be called instead of the class specific release function.
 261  * Only use this if you want to override the default release function, like
 262  * when you are nesting class_device structures.
 263  * @uevent: pointer to a uevent function for this struct class_device.  If
 264  * set, this will be called instead of the class specific uevent function.
 265  * Only use this if you want to override the default uevent function, like
 266  * when you are nesting class_device structures.
 267  */
 268 struct class_device {
 269         struct list_head        node;
 270
 271         struct kobject          kobj;
 272         struct class            *class;
 273         dev_t                   devt;
 274         struct device           *dev;
 275         void                    *class_data;
 276         struct class_device     *parent;
 277         struct attribute_group  **groups;
 278
 279         void (*release)(struct class_device *dev);
 280         int (*uevent)(struct class_device *dev, struct kobj_uevent_env *env);
 281         char class_id[BUS_ID_SIZE];
 282 };
 283
 284 static inline void *class_get_devdata(struct class_device *dev)
 285 {
 286         return dev->class_data;
 287 }
 288
 289 static inline void class_set_devdata(struct class_device *dev, void *data)
 290 {
 291         dev->class_data = data;
 292 }
 293
 294
 295 extern int __must_check class_device_register(struct class_device *);
 296 extern void class_device_unregister(struct class_device *);
 297 extern void class_device_initialize(struct class_device *);
 298 extern int __must_check class_device_add(struct class_device *);
 299 extern void class_device_del(struct class_device *);
 300
 301 extern struct class_device *class_device_get(struct class_device *);
 302 extern void class_device_put(struct class_device *);
 303
 304 extern void class_device_remove_file(struct class_device *,
 305                                      const struct class_device_attribute *);
 306 extern int __must_check class_device_create_bin_file(struct class_device *,
 307                                         struct bin_attribute *);
 308 extern void class_device_remove_bin_file(struct class_device *,
 309                                          struct bin_attribute *);
 310
 311 struct class_interface {
 312         struct list_head        node;
 313         struct class            *class;
 314
 315         int (*add)      (struct class_device *, struct class_interface *);
 316         void (*remove)  (struct class_device *, struct class_interface *);
 317         int (*add_dev)          (struct device *, struct class_interface *);
 318         void (*remove_dev)      (struct device *, struct class_interface *);
 319 };
 320
 321 extern int __must_check class_interface_register(struct class_interface *);
 322 extern void class_interface_unregister(struct class_interface *);
 323
 324 extern struct class *class_create(struct module *owner, const char *name);
 325 extern void class_destroy(struct class *cls);
 326 extern struct class_device *class_device_create(struct class *cls,
 327                                                 struct class_device *parent,
 328                                                 dev_t devt,
 329                                                 struct device *device,
 330                                                 const char *fmt, ...)
 331                                         __attribute__((format(printf, 5, 6)));
 332 extern void class_device_destroy(struct class *cls, dev_t devt);
 333
 334 /*
 335  * The type of device, "struct device" is embedded in. A class
 336  * or bus can contain devices of different types
 337  * like "partitions" and "disks", "mouse" and "event".
 338  * This identifies the device type and carries type-specific
 339  * information, equivalent to the kobj_type of a kobject.
 340  * If "name" is specified, the uevent will contain it in
 341  * the DEVTYPE variable.
 342  */
 343 struct device_type {
 344         const char *name;
 345         struct attribute_group **groups;
 346         int (*uevent)(struct device *dev, struct kobj_uevent_env *env);
 347         void (*release)(struct device *dev);
 348         int (*suspend)(struct device *dev, pm_message_t state);
 349         int (*resume)(struct device *dev);
 350 };
 351
 352 /* interface for exporting device attributes */
 353 struct device_attribute {
 354         struct attribute        attr;
 355         ssize_t (*show)(struct device *dev, struct device_attribute *attr,
 356                         char *buf);
 357         ssize_t (*store)(struct device *dev, struct device_attribute *attr,
 358                          const char *buf, size_t count);
 359 };
 360
 361 #define DEVICE_ATTR(_name, _mode, _show, _store) \
 362 struct device_attribute dev_attr_##_name = __ATTR(_name, _mode, _show, _store)
 363
 364 extern int __must_check device_create_file(struct device *device,
 365                                            struct device_attribute *entry);
 366 extern void device_remove_file(struct device *dev,
 367                                struct device_attribute *attr);
 368 extern int __must_check device_create_bin_file(struct device *dev,
 369                                                struct bin_attribute *attr);
 370 extern void device_remove_bin_file(struct device *dev,
 371                                    struct bin_attribute *attr);
 372 extern int device_schedule_callback_owner(struct device *dev,
 373                 void (*func)(struct device *dev), struct module *owner);
 374
 375 /* This is a macro to avoid include problems with THIS_MODULE */
 376 #define device_schedule_callback(dev, func)                     \
 377         device_schedule_callback_owner(dev, func, THIS_MODULE)
 378
 379 /* device resource management */
 380 typedef void (*dr_release_t)(struct device *dev, void *res);
 381 typedef int (*dr_match_t)(struct device *dev, void *res, void *match_data);
 382
 383 #ifdef CONFIG_DEBUG_DEVRES
 384 extern void *__devres_alloc(dr_release_t release, size_t size, gfp_t gfp,
 385                              const char *name);
 386 #define devres_alloc(release, size, gfp) \
 387         __devres_alloc(release, size, gfp, #release)
 388 #else
 389 extern void *devres_alloc(dr_release_t release, size_t size, gfp_t gfp);
 390 #endif
 391 extern void devres_free(void *res);
 392 extern void devres_add(struct device *dev, void *res);
 393 extern void *devres_find(struct device *dev, dr_release_t release,
 394                          dr_match_t match, void *match_data);
 395 extern void *devres_get(struct device *dev, void *new_res,
 396                         dr_match_t match, void *match_data);
 397 extern void *devres_remove(struct device *dev, dr_release_t release,
 398                            dr_match_t match, void *match_data);
 399 extern int devres_destroy(struct device *dev, dr_release_t release,
 400                           dr_match_t match, void *match_data);
 401
 402 /* devres group */
 403 extern void * __must_check devres_open_group(struct device *dev, void *id,
 404                                              gfp_t gfp);
 405 extern void devres_close_group(struct device *dev, void *id);
 406 extern void devres_remove_group(struct device *dev, void *id);
 407 extern int devres_release_group(struct device *dev, void *id);
 408
 409 /* managed kzalloc/kfree for device drivers, no kmalloc, always use kzalloc */
 410 extern void *devm_kzalloc(struct device *dev, size_t size, gfp_t gfp);
 411 extern void devm_kfree(struct device *dev, void *p);
 412
 413 struct device_dma_parameters {
 414         /*
 415          * a low level driver may set these to teach IOMMU code about
 416          * sg limitations.
 417          */
 418         unsigned int max_segment_size;
 419         unsigned long segment_boundary_mask;
 420 };
 421
 422 struct device {
 423         struct klist            klist_children;
 424         struct klist_node       knode_parent;   /* node in sibling list */
 425         struct klist_node       knode_driver;
 426         struct klist_node       knode_bus;
 427         struct device           *parent;
 428
 429         struct kobject kobj;
 430         char    bus_id[BUS_ID_SIZE];    /* position on parent bus */
 431         struct device_type      *type;
 432         unsigned                is_registered:1;
 433         unsigned                uevent_suppress:1;
 434
 435         struct semaphore        sem;    /* semaphore to synchronize calls to
 436                                          * its driver.
 437                                          */
 438
 439         struct bus_type *bus;           /* type of bus device is on */
 440         struct device_driver *driver;   /* which driver has allocated this
 441                                            device */
 442         void            *driver_data;   /* data private to the driver */
 443         void            *platform_data; /* Platform specific data, device
 444                                            core doesn't touch it */
 445         struct dev_pm_info      power;
 446
 447 #ifdef CONFIG_NUMA
 448         int             numa_node;      /* NUMA node this device is close to */
 449 #endif
 450         u64             *dma_mask;      /* dma mask (if dma'able device) */
 451         u64             coherent_dma_mask;/* Like dma_mask, but for
 452                                              alloc_coherent mappings as
 453                                              not all hardware supports
 454                                              64 bit addresses for consistent
 455                                              allocations such descriptors. */
 456
 457         struct device_dma_parameters *dma_parms;
 458
 459         struct list_head        dma_pools;      /* dma pools (if dma'ble) */
 460
 461         struct dma_coherent_mem *dma_mem; /* internal for coherent mem
 462                                              override */
 463         /* arch specific additions */
 464         struct dev_archdata     archdata;
 465
 466         spinlock_t              devres_lock;
 467         struct list_head        devres_head;
 468
 469         /* class_device migration path */
 470         struct list_head        node;
 471         struct class            *class;
 472         dev_t                   devt;   /* dev_t, creates the sysfs "dev" */
 473         struct attribute_group  **groups;       /* optional groups */
 474
 475         void    (*release)(struct device *dev);
 476 };
 477
 478 /* Get the wakeup routines, which depend on struct device */
 479 #include <linux/pm_wakeup.h>
 480
 481 #ifdef CONFIG_NUMA
 482 static inline int dev_to_node(struct device *dev)
 483 {
 484         return dev->numa_node;
 485 }
 486 static inline void set_dev_node(struct device *dev, int node)
 487 {
 488         dev->numa_node = node;
 489 }
 490 #else
 491 static inline int dev_to_node(struct device *dev)
 492 {
 493         return -1;
 494 }
 495 static inline void set_dev_node(struct device *dev, int node)
 496 {
 497 }
 498 #endif
 499
 500 static inline void *dev_get_drvdata(struct device *dev)
 501 {
 502         return dev->driver_data;
 503 }
 504
 505 static inline void dev_set_drvdata(struct device *dev, void *data)
 506 {
 507         dev->driver_data = data;
 508 }
 509
 510 static inline int device_is_registered(struct device *dev)
 511 {
 512         return dev->is_registered;
 513 }
 514
 515 void driver_init(void);
 516
 517 /*
 518  * High level routines for use by the bus drivers
 519  */
 520 extern int __must_check device_register(struct device *dev);
 521 extern void device_unregister(struct device *dev);
 522 extern void device_initialize(struct device *dev);
 523 extern int __must_check device_add(struct device *dev);
 524 extern void device_del(struct device *dev);
 525 extern int device_for_each_child(struct device *dev, void *data,
 526                      int (*fn)(struct device *dev, void *data));
 527 extern struct device *device_find_child(struct device *dev, void *data,
 528                                 int (*match)(struct device *dev, void *data));
 529 extern int device_rename(struct device *dev, char *new_name);
 530 extern int device_move(struct device *dev, struct device *new_parent);
 531
 532 /*
 533  * Manual binding of a device to driver. See drivers/base/bus.c
 534  * for information on use.
 535  */
 536 extern int __must_check device_bind_driver(struct device *dev);
 537 extern void device_release_driver(struct device *dev);
 538 extern int  __must_check device_attach(struct device *dev);
 539 extern int __must_check driver_attach(struct device_driver *drv);
 540 extern int __must_check device_reprobe(struct device *dev);
 541
 542 /*
 543  * Easy functions for dynamically creating devices on the fly
 544  */
 545 extern struct device *device_create(struct class *cls, struct device *parent,
 546                                     dev_t devt, const char *fmt, ...)
 547                                     __attribute__((format(printf, 4, 5)));
 548 extern void device_destroy(struct class *cls, dev_t devt);
 549 #ifdef CONFIG_PM_SLEEP
 550 extern void destroy_suspended_device(struct class *cls, dev_t devt);
 551 extern void device_pm_schedule_removal(struct device *);
 552 #else /* !CONFIG_PM_SLEEP */
 553 static inline void destroy_suspended_device(struct class *cls, dev_t devt)
 554 {
 555         device_destroy(cls, devt);
 556 }
 557
 558 static inline void device_pm_schedule_removal(struct device *dev)
 559 {
 560         device_unregister(dev);
 561 }
 562 #endif /* !CONFIG_PM_SLEEP */
 563
 564 /*
 565  * Platform "fixup" functions - allow the platform to have their say
 566  * about devices and actions that the general device layer doesn't
 567  * know about.
 568  */
 569 /* Notify platform of device discovery */
 570 extern int (*platform_notify)(struct device *dev);
 571
 572 extern int (*platform_notify_remove)(struct device *dev);
 573
 574
 575 /**
 576  * get_device - atomically increment the reference count for the device.
 577  *
 578  */
 579 extern struct device *get_device(struct device *dev);
 580 extern void put_device(struct device *dev);
 581
 582
 583 /* drivers/base/power/shutdown.c */
 584 extern void device_shutdown(void);
 585
 586 /* drivers/base/sys.c */
 587 extern void sysdev_shutdown(void);
 588
 589 /* debugging and troubleshooting/diagnostic helpers. */
 590 extern const char *dev_driver_string(struct device *dev);
 591 #define dev_printk(level, dev, format, arg...)  \
 592         printk(level "%s %s: " format , dev_driver_string(dev) , \
 593                (dev)->bus_id , ## arg)
 594
 595 #define dev_emerg(dev, format, arg...)          \
 596         dev_printk(KERN_EMERG , dev , format , ## arg)
 597 #define dev_alert(dev, format, arg...)          \
 598         dev_printk(KERN_ALERT , dev , format , ## arg)
 599 #define dev_crit(dev, format, arg...)           \
 600         dev_printk(KERN_CRIT , dev , format , ## arg)
 601 #define dev_err(dev, format, arg...)            \
 602         dev_printk(KERN_ERR , dev , format , ## arg)
 603 #define dev_warn(dev, format, arg...)           \
 604         dev_printk(KERN_WARNING , dev , format , ## arg)
 605 #define dev_notice(dev, format, arg...)         \
 606         dev_printk(KERN_NOTICE , dev , format , ## arg)
 607 #define dev_info(dev, format, arg...)           \
 608         dev_printk(KERN_INFO , dev , format , ## arg)
 609
 610 #ifdef DEBUG
 611 #define dev_dbg(dev, format, arg...)            \
 612         dev_printk(KERN_DEBUG , dev , format , ## arg)
 613 #else
 614 #define dev_dbg(dev, format, arg...)            \
 615         ({ if (0) dev_printk(KERN_DEBUG, dev, format, ##arg); 0; })
 616 #endif
 617
 618 #ifdef VERBOSE_DEBUG
 619 #define dev_vdbg        dev_dbg
 620 #else
 621
 622 #define dev_vdbg(dev, format, arg...)           \
 623         ({ if (0) dev_printk(KERN_DEBUG, dev, format, ##arg); 0; })
 624 #endif
 625
 626 /* Create alias, so I can be autoloaded. */
 627 #define MODULE_ALIAS_CHARDEV(major,minor) \
 628         MODULE_ALIAS("char-major-" __stringify(major) "-" __stringify(minor))
 629 #define MODULE_ALIAS_CHARDEV_MAJOR(major) \
 630         MODULE_ALIAS("char-major-" __stringify(major) "-*")
 631 #endif /* _DEVICE_H_ */