include/drm/ttm/ttm_bo_api.h

   1 /**************************************************************************
   2  *
   3  * Copyright (c) 2006-2009 VMware, Inc., Palo Alto, CA., USA
   4  * All Rights Reserved.
   5  *
   6  * Permission is hereby granted, free of charge, to any person obtaining a
   7  * copy of this software and associated documentation files (the
   8  * "Software"), to deal in the Software without restriction, including
   9  * without limitation the rights to use, copy, modify, merge, publish,
  10  * distribute, sub license, and/or sell copies of the Software, and to
  11  * permit persons to whom the Software is furnished to do so, subject to
  12  * the following conditions:
  13  *
  14  * The above copyright notice and this permission notice (including the
  15  * next paragraph) shall be included in all copies or substantial portions
  16  * of the Software.
  17  *
  18  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  19  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  20  * FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT. IN NO EVENT SHALL
  21  * THE COPYRIGHT HOLDERS, AUTHORS AND/OR ITS SUPPLIERS BE LIABLE FOR ANY CLAIM,
  22  * DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR
  23  * OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE
  24  * USE OR OTHER DEALINGS IN THE SOFTWARE.
  25  *
  26  **************************************************************************/
  27 /*
  28  * Authors: Thomas Hellstrom <thellstrom-at-vmware-dot-com>
  29  */
  30
  31 #ifndef _TTM_BO_API_H_
  32 #define _TTM_BO_API_H_
  33
  34 #include "drm_hashtab.h"
  35 #include <linux/kref.h>
  36 #include <linux/list.h>
  37 #include <linux/wait.h>
  38 #include <linux/mutex.h>
  39 #include <linux/mm.h>
  40 #include <linux/rbtree.h>
  41 #include <linux/bitmap.h>
  42
  43 struct ttm_bo_device;
  44
  45 struct drm_mm_node;
  46
  47
  48 /**
  49  * struct ttm_placement
  50  *
  51  * @fpfn:               first valid page frame number to put the object
  52  * @lpfn:               last valid page frame number to put the object
  53  * @num_placement:      number of prefered placements
  54  * @placement:          prefered placements
  55  * @num_busy_placement: number of prefered placements when need to evict buffer
  56  * @busy_placement:     prefered placements when need to evict buffer
  57  *
  58  * Structure indicating the placement you request for an object.
  59  */
  60 struct ttm_placement {
  61         unsigned        fpfn;
  62         unsigned        lpfn;
  63         unsigned        num_placement;
  64         const uint32_t  *placement;
  65         unsigned        num_busy_placement;
  66         const uint32_t  *busy_placement;
  67 };
  68
  69 /**
  70  * struct ttm_bus_placement
  71  *
  72  * @addr:               mapped virtual address
  73  * @base:               bus base address
  74  * @is_iomem:           is this io memory ?
  75  * @size:               size in byte
  76  * @offset:             offset from the base address
  77  *
  78  * Structure indicating the bus placement of an object.
  79  */
  80 struct ttm_bus_placement {
  81         void            *addr;
  82         unsigned long   base;
  83         unsigned long   size;
  84         unsigned long   offset;
  85         bool            is_iomem;
  86         bool            io_reserved;
  87 };
  88
  89
  90 /**
  91  * struct ttm_mem_reg
  92  *
  93  * @mm_node: Memory manager node.
  94  * @size: Requested size of memory region.
  95  * @num_pages: Actual size of memory region in pages.
  96  * @page_alignment: Page alignment.
  97  * @placement: Placement flags.
  98  * @bus: Placement on io bus accessible to the CPU
  99  *
 100  * Structure indicating the placement and space resources used by a
 101  * buffer object.
 102  */
 103
 104 struct ttm_mem_reg {
 105         struct drm_mm_node *mm_node;
 106         unsigned long size;
 107         unsigned long num_pages;
 108         uint32_t page_alignment;
 109         uint32_t mem_type;
 110         uint32_t placement;
 111         struct ttm_bus_placement bus;
 112 };
 113
 114 /**
 115  * enum ttm_bo_type
 116  *
 117  * @ttm_bo_type_device: These are 'normal' buffers that can
 118  * be mmapped by user space. Each of these bos occupy a slot in the
 119  * device address space, that can be used for normal vm operations.
 120  *
 121  * @ttm_bo_type_user: These are user-space memory areas that are made
 122  * available to the GPU by mapping the buffer pages into the GPU aperture
 123  * space. These buffers cannot be mmaped from the device address space.
 124  *
 125  * @ttm_bo_type_kernel: These buffers are like ttm_bo_type_device buffers,
 126  * but they cannot be accessed from user-space. For kernel-only use.
 127  */
 128
 129 enum ttm_bo_type {
 130         ttm_bo_type_device,
 131         ttm_bo_type_user,
 132         ttm_bo_type_kernel
 133 };
 134
 135 struct ttm_tt;
 136
 137 /**
 138  * struct ttm_buffer_object
 139  *
 140  * @bdev: Pointer to the buffer object device structure.
 141  * @buffer_start: The virtual user-space start address of ttm_bo_type_user
 142  * buffers.
 143  * @type: The bo type.
 144  * @destroy: Destruction function. If NULL, kfree is used.
 145  * @num_pages: Actual number of pages.
 146  * @addr_space_offset: Address space offset.
 147  * @acc_size: Accounted size for this object.
 148  * @kref: Reference count of this buffer object. When this refcount reaches
 149  * zero, the object is put on the delayed delete list.
 150  * @list_kref: List reference count of this buffer object. This member is
 151  * used to avoid destruction while the buffer object is still on a list.
 152  * Lru lists may keep one refcount, the delayed delete list, and kref != 0
 153  * keeps one refcount. When this refcount reaches zero,
 154  * the object is destroyed.
 155  * @event_queue: Queue for processes waiting on buffer object status change.
 156  * @lock: spinlock protecting mostly synchronization members.
 157  * @mem: structure describing current placement.
 158  * @persistant_swap_storage: Usually the swap storage is deleted for buffers
 159  * pinned in physical memory. If this behaviour is not desired, this member
 160  * holds a pointer to a persistant shmem object.
 161  * @ttm: TTM structure holding system pages.
 162  * @evicted: Whether the object was evicted without user-space knowing.
 163  * @cpu_writes: For synchronization. Number of cpu writers.
 164  * @lru: List head for the lru list.
 165  * @ddestroy: List head for the delayed destroy list.
 166  * @swap: List head for swap LRU list.
 167  * @val_seq: Sequence of the validation holding the @reserved lock.
 168  * Used to avoid starvation when many processes compete to validate the
 169  * buffer. This member is protected by the bo_device::lru_lock.
 170  * @seq_valid: The value of @val_seq is valid. This value is protected by
 171  * the bo_device::lru_lock.
 172  * @reserved: Deadlock-free lock used for synchronization state transitions.
 173  * @sync_obj_arg: Opaque argument to synchronization object function.
 174  * @sync_obj: Pointer to a synchronization object.
 175  * @priv_flags: Flags describing buffer object internal state.
 176  * @vm_rb: Rb node for the vm rb tree.
 177  * @vm_node: Address space manager node.
 178  * @offset: The current GPU offset, which can have different meanings
 179  * depending on the memory type. For SYSTEM type memory, it should be 0.
 180  * @cur_placement: Hint of current placement.
 181  *
 182  * Base class for TTM buffer object, that deals with data placement and CPU
 183  * mappings. GPU mappings are really up to the driver, but for simpler GPUs
 184  * the driver can usually use the placement offset @offset directly as the
 185  * GPU virtual address. For drivers implementing multiple
 186  * GPU memory manager contexts, the driver should manage the address space
 187  * in these contexts separately and use these objects to get the correct
 188  * placement and caching for these GPU maps. This makes it possible to use
 189  * these objects for even quite elaborate memory management schemes.
 190  * The destroy member, the API visibility of this object makes it possible
 191  * to derive driver specific types.
 192  */
 193
 194 struct ttm_buffer_object {
 195         /**
 196          * Members constant at init.
 197          */
 198
 199         struct ttm_bo_global *glob;
 200         struct ttm_bo_device *bdev;
 201         unsigned long buffer_start;
 202         enum ttm_bo_type type;
 203         void (*destroy) (struct ttm_buffer_object *);
 204         unsigned long num_pages;
 205         uint64_t addr_space_offset;
 206         size_t acc_size;
 207
 208         /**
 209         * Members not needing protection.
 210         */
 211
 212         struct kref kref;
 213         struct kref list_kref;
 214         wait_queue_head_t event_queue;
 215         spinlock_t lock;
 216
 217         /**
 218          * Members protected by the bo::reserved lock.
 219          */
 220
 221         struct ttm_mem_reg mem;
 222         struct file *persistant_swap_storage;
 223         struct ttm_tt *ttm;
 224         bool evicted;
 225
 226         /**
 227          * Members protected by the bo::reserved lock only when written to.
 228          */
 229
 230         atomic_t cpu_writers;
 231
 232         /**
 233          * Members protected by the bdev::lru_lock.
 234          */
 235
 236         struct list_head lru;
 237         struct list_head ddestroy;
 238         struct list_head swap;
 239         uint32_t val_seq;
 240         bool seq_valid;
 241
 242         /**
 243          * Members protected by the bdev::lru_lock
 244          * only when written to.
 245          */
 246
 247         atomic_t reserved;
 248
 249
 250         /**
 251          * Members protected by the bo::lock
 252          */
 253
 254         void *sync_obj_arg;
 255         void *sync_obj;
 256         unsigned long priv_flags;
 257
 258         /**
 259          * Members protected by the bdev::vm_lock
 260          */
 261
 262         struct rb_node vm_rb;
 263         struct drm_mm_node *vm_node;
 264
 265
 266         /**
 267          * Special members that are protected by the reserve lock
 268          * and the bo::lock when written to. Can be read with
 269          * either of these locks held.
 270          */
 271
 272         unsigned long offset;
 273         uint32_t cur_placement;
 274 };
 275
 276 /**
 277  * struct ttm_bo_kmap_obj
 278  *
 279  * @virtual: The current kernel virtual address.
 280  * @page: The page when kmap'ing a single page.
 281  * @bo_kmap_type: Type of bo_kmap.
 282  *
 283  * Object describing a kernel mapping. Since a TTM bo may be located
 284  * in various memory types with various caching policies, the
 285  * mapping can either be an ioremap, a vmap, a kmap or part of a
 286  * premapped region.
 287  */
 288
 289 #define TTM_BO_MAP_IOMEM_MASK 0x80
 290 struct ttm_bo_kmap_obj {
 291         void *virtual;
 292         struct page *page;
 293         enum {
 294                 ttm_bo_map_iomap        = 1 | TTM_BO_MAP_IOMEM_MASK,
 295                 ttm_bo_map_vmap         = 2,
 296                 ttm_bo_map_kmap         = 3,
 297                 ttm_bo_map_premapped    = 4 | TTM_BO_MAP_IOMEM_MASK,
 298         } bo_kmap_type;
 299         struct ttm_buffer_object *bo;
 300 };
 301
 302 /**
 303  * ttm_bo_reference - reference a struct ttm_buffer_object
 304  *
 305  * @bo: The buffer object.
 306  *
 307  * Returns a refcounted pointer to a buffer object.
 308  */
 309
 310 static inline struct ttm_buffer_object *
 311 ttm_bo_reference(struct ttm_buffer_object *bo)
 312 {
 313         kref_get(&bo->kref);
 314         return bo;
 315 }
 316
 317 /**
 318  * ttm_bo_wait - wait for buffer idle.
 319  *
 320  * @bo:  The buffer object.
 321  * @interruptible:  Use interruptible wait.
 322  * @no_wait:  Return immediately if buffer is busy.
 323  *
 324  * This function must be called with the bo::mutex held, and makes
 325  * sure any previous rendering to the buffer is completed.
 326  * Note: It might be necessary to block validations before the
 327  * wait by reserving the buffer.
 328  * Returns -EBUSY if no_wait is true and the buffer is busy.
 329  * Returns -ERESTARTSYS if interrupted by a signal.
 330  */
 331 extern int ttm_bo_wait(struct ttm_buffer_object *bo, bool lazy,
 332                        bool interruptible, bool no_wait);
 333 /**
 334  * ttm_bo_validate
 335  *
 336  * @bo: The buffer object.
 337  * @placement: Proposed placement for the buffer object.
 338  * @interruptible: Sleep interruptible if sleeping.
 339  * @no_wait_reserve: Return immediately if other buffers are busy.
 340  * @no_wait_gpu: Return immediately if the GPU is busy.
 341  *
 342  * Changes placement and caching policy of the buffer object
 343  * according proposed placement.
 344  * Returns
 345  * -EINVAL on invalid proposed placement.
 346  * -ENOMEM on out-of-memory condition.
 347  * -EBUSY if no_wait is true and buffer busy.
 348  * -ERESTARTSYS if interrupted by a signal.
 349  */
 350 extern int ttm_bo_validate(struct ttm_buffer_object *bo,
 351                                 struct ttm_placement *placement,
 352                                 bool interruptible, bool no_wait_reserve,
 353                                 bool no_wait_gpu);
 354
 355 /**
 356  * ttm_bo_unref
 357  *
 358  * @bo: The buffer object.
 359  *
 360  * Unreference and clear a pointer to a buffer object.
 361  */
 362 extern void ttm_bo_unref(struct ttm_buffer_object **bo);
 363
 364 /**
 365  * ttm_bo_synccpu_write_grab
 366  *
 367  * @bo: The buffer object:
 368  * @no_wait: Return immediately if buffer is busy.
 369  *
 370  * Synchronizes a buffer object for CPU RW access. This means
 371  * blocking command submission that affects the buffer and
 372  * waiting for buffer idle. This lock is recursive.
 373  * Returns
 374  * -EBUSY if the buffer is busy and no_wait is true.
 375  * -ERESTARTSYS if interrupted by a signal.
 376  */
 377
 378 extern int
 379 ttm_bo_synccpu_write_grab(struct ttm_buffer_object *bo, bool no_wait);
 380 /**
 381  * ttm_bo_synccpu_write_release:
 382  *
 383  * @bo : The buffer object.
 384  *
 385  * Releases a synccpu lock.
 386  */
 387 extern void ttm_bo_synccpu_write_release(struct ttm_buffer_object *bo);
 388
 389 /**
 390  * ttm_bo_init
 391  *
 392  * @bdev: Pointer to a ttm_bo_device struct.
 393  * @bo: Pointer to a ttm_buffer_object to be initialized.
 394  * @size: Requested size of buffer object.
 395  * @type: Requested type of buffer object.
 396  * @flags: Initial placement flags.
 397  * @page_alignment: Data alignment in pages.
 398  * @buffer_start: Virtual address of user space data backing a
 399  * user buffer object.
 400  * @interruptible: If needing to sleep to wait for GPU resources,
 401  * sleep interruptible.
 402  * @persistant_swap_storage: Usually the swap storage is deleted for buffers
 403  * pinned in physical memory. If this behaviour is not desired, this member
 404  * holds a pointer to a persistant shmem object. Typically, this would
 405  * point to the shmem object backing a GEM object if TTM is used to back a
 406  * GEM user interface.
 407  * @acc_size: Accounted size for this object.
 408  * @destroy: Destroy function. Use NULL for kfree().
 409  *
 410  * This function initializes a pre-allocated struct ttm_buffer_object.
 411  * As this object may be part of a larger structure, this function,
 412  * together with the @destroy function,
 413  * enables driver-specific objects derived from a ttm_buffer_object.
 414  * On successful return, the object kref and list_kref are set to 1.
 415  * Returns
 416  * -ENOMEM: Out of memory.
 417  * -EINVAL: Invalid placement flags.
 418  * -ERESTARTSYS: Interrupted by signal while sleeping waiting for resources.
 419  */
 420
 421 extern int ttm_bo_init(struct ttm_bo_device *bdev,
 422                         struct ttm_buffer_object *bo,
 423                         unsigned long size,
 424                         enum ttm_bo_type type,
 425                         struct ttm_placement *placement,
 426                         uint32_t page_alignment,
 427                         unsigned long buffer_start,
 428                         bool interrubtible,
 429                         struct file *persistant_swap_storage,
 430                         size_t acc_size,
 431                         void (*destroy) (struct ttm_buffer_object *));
 432 /**
 433  * ttm_bo_synccpu_object_init
 434  *
 435  * @bdev: Pointer to a ttm_bo_device struct.
 436  * @bo: Pointer to a ttm_buffer_object to be initialized.
 437  * @size: Requested size of buffer object.
 438  * @type: Requested type of buffer object.
 439  * @flags: Initial placement flags.
 440  * @page_alignment: Data alignment in pages.
 441  * @buffer_start: Virtual address of user space data backing a
 442  * user buffer object.
 443  * @interruptible: If needing to sleep while waiting for GPU resources,
 444  * sleep interruptible.
 445  * @persistant_swap_storage: Usually the swap storage is deleted for buffers
 446  * pinned in physical memory. If this behaviour is not desired, this member
 447  * holds a pointer to a persistant shmem object. Typically, this would
 448  * point to the shmem object backing a GEM object if TTM is used to back a
 449  * GEM user interface.
 450  * @p_bo: On successful completion *p_bo points to the created object.
 451  *
 452  * This function allocates a ttm_buffer_object, and then calls ttm_bo_init
 453  * on that object. The destroy function is set to kfree().
 454  * Returns
 455  * -ENOMEM: Out of memory.
 456  * -EINVAL: Invalid placement flags.
 457  * -ERESTARTSYS: Interrupted by signal while waiting for resources.
 458  */
 459
 460 extern int ttm_bo_create(struct ttm_bo_device *bdev,
 461                                 unsigned long size,
 462                                 enum ttm_bo_type type,
 463                                 struct ttm_placement *placement,
 464                                 uint32_t page_alignment,
 465                                 unsigned long buffer_start,
 466                                 bool interruptible,
 467                                 struct file *persistant_swap_storage,
 468                                 struct ttm_buffer_object **p_bo);
 469
 470 /**
 471  * ttm_bo_check_placement
 472  *
 473  * @bo:         the buffer object.
 474  * @placement:  placements
 475  *
 476  * Performs minimal validity checking on an intended change of
 477  * placement flags.
 478  * Returns
 479  * -EINVAL: Intended change is invalid or not allowed.
 480  */
 481 extern int ttm_bo_check_placement(struct ttm_buffer_object *bo,
 482                                         struct ttm_placement *placement);
 483
 484 /**
 485  * ttm_bo_init_mm
 486  *
 487  * @bdev: Pointer to a ttm_bo_device struct.
 488  * @mem_type: The memory type.
 489  * @p_size: size managed area in pages.
 490  *
 491  * Initialize a manager for a given memory type.
 492  * Note: if part of driver firstopen, it must be protected from a
 493  * potentially racing lastclose.
 494  * Returns:
 495  * -EINVAL: invalid size or memory type.
 496  * -ENOMEM: Not enough memory.
 497  * May also return driver-specified errors.
 498  */
 499
 500 extern int ttm_bo_init_mm(struct ttm_bo_device *bdev, unsigned type,
 501                                 unsigned long p_size);
 502 /**
 503  * ttm_bo_clean_mm
 504  *
 505  * @bdev: Pointer to a ttm_bo_device struct.
 506  * @mem_type: The memory type.
 507  *
 508  * Take down a manager for a given memory type after first walking
 509  * the LRU list to evict any buffers left alive.
 510  *
 511  * Normally, this function is part of lastclose() or unload(), and at that
 512  * point there shouldn't be any buffers left created by user-space, since
 513  * there should've been removed by the file descriptor release() method.
 514  * However, before this function is run, make sure to signal all sync objects,
 515  * and verify that the delayed delete queue is empty. The driver must also
 516  * make sure that there are no NO_EVICT buffers present in this memory type
 517  * when the call is made.
 518  *
 519  * If this function is part of a VT switch, the caller must make sure that
 520  * there are no appications currently validating buffers before this
 521  * function is called. The caller can do that by first taking the
 522  * struct ttm_bo_device::ttm_lock in write mode.
 523  *
 524  * Returns:
 525  * -EINVAL: invalid or uninitialized memory type.
 526  * -EBUSY: There are still buffers left in this memory type.
 527  */
 528
 529 extern int ttm_bo_clean_mm(struct ttm_bo_device *bdev, unsigned mem_type);
 530
 531 /**
 532  * ttm_bo_evict_mm
 533  *
 534  * @bdev: Pointer to a ttm_bo_device struct.
 535  * @mem_type: The memory type.
 536  *
 537  * Evicts all buffers on the lru list of the memory type.
 538  * This is normally part of a VT switch or an
 539  * out-of-memory-space-due-to-fragmentation handler.
 540  * The caller must make sure that there are no other processes
 541  * currently validating buffers, and can do that by taking the
 542  * struct ttm_bo_device::ttm_lock in write mode.
 543  *
 544  * Returns:
 545  * -EINVAL: Invalid or uninitialized memory type.
 546  * -ERESTARTSYS: The call was interrupted by a signal while waiting to
 547  * evict a buffer.
 548  */
 549
 550 extern int ttm_bo_evict_mm(struct ttm_bo_device *bdev, unsigned mem_type);
 551
 552 /**
 553  * ttm_kmap_obj_virtual
 554  *
 555  * @map: A struct ttm_bo_kmap_obj returned from ttm_bo_kmap.
 556  * @is_iomem: Pointer to an integer that on return indicates 1 if the
 557  * virtual map is io memory, 0 if normal memory.
 558  *
 559  * Returns the virtual address of a buffer object area mapped by ttm_bo_kmap.
 560  * If *is_iomem is 1 on return, the virtual address points to an io memory area,
 561  * that should strictly be accessed by the iowriteXX() and similar functions.
 562  */
 563
 564 static inline void *ttm_kmap_obj_virtual(struct ttm_bo_kmap_obj *map,
 565                                          bool *is_iomem)
 566 {
 567         *is_iomem = !!(map->bo_kmap_type & TTM_BO_MAP_IOMEM_MASK);
 568         return map->virtual;
 569 }
 570
 571 /**
 572  * ttm_bo_kmap
 573  *
 574  * @bo: The buffer object.
 575  * @start_page: The first page to map.
 576  * @num_pages: Number of pages to map.
 577  * @map: pointer to a struct ttm_bo_kmap_obj representing the map.
 578  *
 579  * Sets up a kernel virtual mapping, using ioremap, vmap or kmap to the
 580  * data in the buffer object. The ttm_kmap_obj_virtual function can then be
 581  * used to obtain a virtual address to the data.
 582  *
 583  * Returns
 584  * -ENOMEM: Out of memory.
 585  * -EINVAL: Invalid range.
 586  */
 587
 588 extern int ttm_bo_kmap(struct ttm_buffer_object *bo, unsigned long start_page,
 589                        unsigned long num_pages, struct ttm_bo_kmap_obj *map);
 590
 591 /**
 592  * ttm_bo_kunmap
 593  *
 594  * @map: Object describing the map to unmap.
 595  *
 596  * Unmaps a kernel map set up by ttm_bo_kmap.
 597  */
 598
 599 extern void ttm_bo_kunmap(struct ttm_bo_kmap_obj *map);
 600
 601 #if 0
 602 #endif
 603
 604 /**
 605  * ttm_fbdev_mmap - mmap fbdev memory backed by a ttm buffer object.
 606  *
 607  * @vma:       vma as input from the fbdev mmap method.
 608  * @bo:        The bo backing the address space. The address space will
 609  * have the same size as the bo, and start at offset 0.
 610  *
 611  * This function is intended to be called by the fbdev mmap method
 612  * if the fbdev address space is to be backed by a bo.
 613  */
 614
 615 extern int ttm_fbdev_mmap(struct vm_area_struct *vma,
 616                           struct ttm_buffer_object *bo);
 617
 618 /**
 619  * ttm_bo_mmap - mmap out of the ttm device address space.
 620  *
 621  * @filp:      filp as input from the mmap method.
 622  * @vma:       vma as input from the mmap method.
 623  * @bdev:      Pointer to the ttm_bo_device with the address space manager.
 624  *
 625  * This function is intended to be called by the device mmap method.
 626  * if the device address space is to be backed by the bo manager.
 627  */
 628
 629 extern int ttm_bo_mmap(struct file *filp, struct vm_area_struct *vma,
 630                        struct ttm_bo_device *bdev);
 631
 632 /**
 633  * ttm_bo_io
 634  *
 635  * @bdev:      Pointer to the struct ttm_bo_device.
 636  * @filp:      Pointer to the struct file attempting to read / write.
 637  * @wbuf:      User-space pointer to address of buffer to write. NULL on read.
 638  * @rbuf:      User-space pointer to address of buffer to read into.
 639  * Null on write.
 640  * @count:     Number of bytes to read / write.
 641  * @f_pos:     Pointer to current file position.
 642  * @write:     1 for read, 0 for write.
 643  *
 644  * This function implements read / write into ttm buffer objects, and is
 645  * intended to
 646  * be called from the fops::read and fops::write method.
 647  * Returns:
 648  * See man (2) write, man(2) read. In particular,
 649  * the function may return -ERESTARTSYS if
 650  * interrupted by a signal.
 651  */
 652
 653 extern ssize_t ttm_bo_io(struct ttm_bo_device *bdev, struct file *filp,
 654                          const char __user *wbuf, char __user *rbuf,
 655                          size_t count, loff_t *f_pos, bool write);
 656
 657 extern void ttm_bo_swapout_all(struct ttm_bo_device *bdev);
 658
 659 #endif