xref: /freebsd/sys/dev/drm2/ttm/ttm_bo_api.h (revision 7fdf597e96a02165cfe22ff357b857d5fa15ed8a)
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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 <dev/drm2/drmP.h>
35 
36 struct ttm_bo_device;
37 
38 struct drm_mm_node;
39 
40 
41 /**
42  * struct ttm_placement
43  *
44  * @fpfn:		first valid page frame number to put the object
45  * @lpfn:		last valid page frame number to put the object
46  * @num_placement:	number of preferred placements
47  * @placement:		preferred placements
48  * @num_busy_placement:	number of preferred placements when need to evict buffer
49  * @busy_placement:	preferred placements when need to evict buffer
50  *
51  * Structure indicating the placement you request for an object.
52  */
53 struct ttm_placement {
54 	unsigned	fpfn;
55 	unsigned	lpfn;
56 	unsigned	num_placement;
57 	const uint32_t	*placement;
58 	unsigned	num_busy_placement;
59 	const uint32_t	*busy_placement;
60 };
61 
62 /**
63  * struct ttm_bus_placement
64  *
65  * @addr:		mapped virtual address
66  * @base:		bus base address
67  * @is_iomem:		is this io memory ?
68  * @size:		size in byte
69  * @offset:		offset from the base address
70  * @io_reserved_vm:     The VM system has a refcount in @io_reserved_count
71  * @io_reserved_count:  Refcounting the numbers of callers to ttm_mem_io_reserve
72  *
73  * Structure indicating the bus placement of an object.
74  */
75 struct ttm_bus_placement {
76 	void		*addr;
77 	unsigned long	base;
78 	unsigned long	size;
79 	unsigned long	offset;
80 	bool		is_iomem;
81 	bool		io_reserved_vm;
82 	uint64_t        io_reserved_count;
83 };
84 
85 
86 /**
87  * struct ttm_mem_reg
88  *
89  * @mm_node: Memory manager node.
90  * @size: Requested size of memory region.
91  * @num_pages: Actual size of memory region in pages.
92  * @page_alignment: Page alignment.
93  * @placement: Placement flags.
94  * @bus: Placement on io bus accessible to the CPU
95  *
96  * Structure indicating the placement and space resources used by a
97  * buffer object.
98  */
99 
100 struct ttm_mem_reg {
101 	void *mm_node;
102 	unsigned long start;
103 	unsigned long size;
104 	unsigned long num_pages;
105 	uint32_t page_alignment;
106 	uint32_t mem_type;
107 	uint32_t placement;
108 	struct ttm_bus_placement bus;
109 };
110 
111 /**
112  * enum ttm_bo_type
113  *
114  * @ttm_bo_type_device:	These are 'normal' buffers that can
115  * be mmapped by user space. Each of these bos occupy a slot in the
116  * device address space, that can be used for normal vm operations.
117  *
118  * @ttm_bo_type_kernel: These buffers are like ttm_bo_type_device buffers,
119  * but they cannot be accessed from user-space. For kernel-only use.
120  *
121  * @ttm_bo_type_sg: Buffer made from dmabuf sg table shared with another
122  * driver.
123  */
124 
125 enum ttm_bo_type {
126 	ttm_bo_type_device,
127 	ttm_bo_type_kernel,
128 	ttm_bo_type_sg
129 };
130 
131 struct ttm_tt;
132 
133 /**
134  * struct ttm_buffer_object
135  *
136  * @bdev: Pointer to the buffer object device structure.
137  * @type: The bo type.
138  * @destroy: Destruction function. If NULL, kfree is used.
139  * @num_pages: Actual number of pages.
140  * @addr_space_offset: Address space offset.
141  * @acc_size: Accounted size for this object.
142  * @kref: Reference count of this buffer object. When this refcount reaches
143  * zero, the object is put on the delayed delete list.
144  * @list_kref: List reference count of this buffer object. This member is
145  * used to avoid destruction while the buffer object is still on a list.
146  * Lru lists may keep one refcount, the delayed delete list, and kref != 0
147  * keeps one refcount. When this refcount reaches zero,
148  * the object is destroyed.
149  * @event_queue: Queue for processes waiting on buffer object status change.
150  * @mem: structure describing current placement.
151  * @persistent_swap_storage: Usually the swap storage is deleted for buffers
152  * pinned in physical memory. If this behaviour is not desired, this member
153  * holds a pointer to a persistent shmem object.
154  * @ttm: TTM structure holding system pages.
155  * @evicted: Whether the object was evicted without user-space knowing.
156  * @cpu_writes: For synchronization. Number of cpu writers.
157  * @lru: List head for the lru list.
158  * @ddestroy: List head for the delayed destroy list.
159  * @swap: List head for swap LRU list.
160  * @val_seq: Sequence of the validation holding the @reserved lock.
161  * Used to avoid starvation when many processes compete to validate the
162  * buffer. This member is protected by the bo_device::lru_lock.
163  * @seq_valid: The value of @val_seq is valid. This value is protected by
164  * the bo_device::lru_lock.
165  * @reserved: Deadlock-free lock used for synchronization state transitions.
166  * @sync_obj: Pointer to a synchronization object.
167  * @priv_flags: Flags describing buffer object internal state.
168  * @vm_rb: Rb node for the vm rb tree.
169  * @vm_node: Address space manager node.
170  * @offset: The current GPU offset, which can have different meanings
171  * depending on the memory type. For SYSTEM type memory, it should be 0.
172  * @cur_placement: Hint of current placement.
173  *
174  * Base class for TTM buffer object, that deals with data placement and CPU
175  * mappings. GPU mappings are really up to the driver, but for simpler GPUs
176  * the driver can usually use the placement offset @offset directly as the
177  * GPU virtual address. For drivers implementing multiple
178  * GPU memory manager contexts, the driver should manage the address space
179  * in these contexts separately and use these objects to get the correct
180  * placement and caching for these GPU maps. This makes it possible to use
181  * these objects for even quite elaborate memory management schemes.
182  * The destroy member, the API visibility of this object makes it possible
183  * to derive driver specific types.
184  */
185 
186 struct ttm_buffer_object {
187 	/**
188 	 * Members constant at init.
189 	 */
190 
191 	struct ttm_bo_global *glob;
192 	struct ttm_bo_device *bdev;
193 	enum ttm_bo_type type;
194 	void (*destroy) (struct ttm_buffer_object *);
195 	unsigned long num_pages;
196 	uint64_t addr_space_offset;
197 	size_t acc_size;
198 
199 	/**
200 	* Members not needing protection.
201 	*/
202 
203 	u_int kref;
204 	u_int list_kref;
205 	/* wait_queue_head_t event_queue; */
206 
207 	/**
208 	 * Members protected by the bo::reserved lock.
209 	 */
210 
211 	struct ttm_mem_reg mem;
212 	struct vm_object *persistent_swap_storage;
213 	struct ttm_tt *ttm;
214 	bool evicted;
215 
216 	/**
217 	 * Members protected by the bo::reserved lock only when written to.
218 	 */
219 
220 	atomic_t cpu_writers;
221 
222 	/**
223 	 * Members protected by the bdev::lru_lock.
224 	 */
225 
226 	struct list_head lru;
227 	struct list_head ddestroy;
228 	struct list_head swap;
229 	struct list_head io_reserve_lru;
230 	uint32_t val_seq;
231 	bool seq_valid;
232 
233 	/**
234 	 * Members protected by the bdev::lru_lock
235 	 * only when written to.
236 	 */
237 
238 	atomic_t reserved;
239 
240 	/**
241 	 * Members protected by struct buffer_object_device::fence_lock
242 	 * In addition, setting sync_obj to anything else
243 	 * than NULL requires bo::reserved to be held. This allows for
244 	 * checking NULL while reserved but not holding the mentioned lock.
245 	 */
246 
247 	void *sync_obj;
248 	unsigned long priv_flags;
249 
250 	/**
251 	 * Members protected by the bdev::vm_lock
252 	 */
253 
254 	RB_ENTRY(ttm_buffer_object) vm_rb;
255 	struct drm_mm_node *vm_node;
256 
257 
258 	/**
259 	 * Special members that are protected by the reserve lock
260 	 * and the bo::lock when written to. Can be read with
261 	 * either of these locks held.
262 	 */
263 
264 	unsigned long offset;
265 	uint32_t cur_placement;
266 
267 	struct sg_table *sg;
268 };
269 
270 /**
271  * struct ttm_bo_kmap_obj
272  *
273  * @virtual: The current kernel virtual address.
274  * @page: The page when kmap'ing a single page.
275  * @bo_kmap_type: Type of bo_kmap.
276  *
277  * Object describing a kernel mapping. Since a TTM bo may be located
278  * in various memory types with various caching policies, the
279  * mapping can either be an ioremap, a vmap, a kmap or part of a
280  * premapped region.
281  */
282 
283 #define TTM_BO_MAP_IOMEM_MASK 0x80
284 struct ttm_bo_kmap_obj {
285 	void *virtual;
286 	struct vm_page *page;
287 	struct sf_buf *sf;
288 	int num_pages;
289 	unsigned long size;
290 	enum {
291 		ttm_bo_map_iomap        = 1 | TTM_BO_MAP_IOMEM_MASK,
292 		ttm_bo_map_vmap         = 2,
293 		ttm_bo_map_kmap         = 3,
294 		ttm_bo_map_premapped    = 4 | TTM_BO_MAP_IOMEM_MASK,
295 	} bo_kmap_type;
296 	struct ttm_buffer_object *bo;
297 };
298 
299 /**
300  * ttm_bo_reference - reference a struct ttm_buffer_object
301  *
302  * @bo: The buffer object.
303  *
304  * Returns a refcounted pointer to a buffer object.
305  */
306 
307 static inline struct ttm_buffer_object *
308 ttm_bo_reference(struct ttm_buffer_object *bo)
309 {
310 	refcount_acquire(&bo->kref);
311 	return bo;
312 }
313 
314 /**
315  * ttm_bo_wait - wait for buffer idle.
316  *
317  * @bo:  The buffer object.
318  * @interruptible:  Use interruptible wait.
319  * @no_wait:  Return immediately if buffer is busy.
320  *
321  * This function must be called with the bo::mutex held, and makes
322  * sure any previous rendering to the buffer is completed.
323  * Note: It might be necessary to block validations before the
324  * wait by reserving the buffer.
325  * Returns -EBUSY if no_wait is true and the buffer is busy.
326  * Returns -ERESTARTSYS if interrupted by a signal.
327  */
328 extern int ttm_bo_wait(struct ttm_buffer_object *bo, bool lazy,
329 		       bool interruptible, bool no_wait);
330 /**
331  * ttm_bo_validate
332  *
333  * @bo: The buffer object.
334  * @placement: Proposed placement for the buffer object.
335  * @interruptible: Sleep interruptible if sleeping.
336  * @no_wait_gpu: Return immediately if the GPU is busy.
337  *
338  * Changes placement and caching policy of the buffer object
339  * according proposed placement.
340  * Returns
341  * -EINVAL on invalid proposed placement.
342  * -ENOMEM on out-of-memory condition.
343  * -EBUSY if no_wait is true and buffer busy.
344  * -ERESTARTSYS if interrupted by a signal.
345  */
346 extern int ttm_bo_validate(struct ttm_buffer_object *bo,
347 				struct ttm_placement *placement,
348 				bool interruptible,
349 				bool no_wait_gpu);
350 
351 /**
352  * ttm_bo_unref
353  *
354  * @bo: The buffer object.
355  *
356  * Unreference and clear a pointer to a buffer object.
357  */
358 extern void ttm_bo_unref(struct ttm_buffer_object **bo);
359 
360 
361 /**
362  * ttm_bo_list_ref_sub
363  *
364  * @bo: The buffer object.
365  * @count: The number of references with which to decrease @bo::list_kref;
366  * @never_free: The refcount should not reach zero with this operation.
367  *
368  * Release @count lru list references to this buffer object.
369  */
370 extern void ttm_bo_list_ref_sub(struct ttm_buffer_object *bo, int count,
371 				bool never_free);
372 
373 /**
374  * ttm_bo_add_to_lru
375  *
376  * @bo: The buffer object.
377  *
378  * Add this bo to the relevant mem type lru and, if it's backed by
379  * system pages (ttms) to the swap list.
380  * This function must be called with struct ttm_bo_global::lru_lock held, and
381  * is typically called immediately prior to unreserving a bo.
382  */
383 extern void ttm_bo_add_to_lru(struct ttm_buffer_object *bo);
384 
385 /**
386  * ttm_bo_del_from_lru
387  *
388  * @bo: The buffer object.
389  *
390  * Remove this bo from all lru lists used to lookup and reserve an object.
391  * This function must be called with struct ttm_bo_global::lru_lock held,
392  * and is usually called just immediately after the bo has been reserved to
393  * avoid recursive reservation from lru lists.
394  */
395 extern int ttm_bo_del_from_lru(struct ttm_buffer_object *bo);
396 
397 
398 /**
399  * ttm_bo_lock_delayed_workqueue
400  *
401  * Prevent the delayed workqueue from running.
402  * Returns
403  * True if the workqueue was queued at the time
404  */
405 extern int ttm_bo_lock_delayed_workqueue(struct ttm_bo_device *bdev);
406 
407 /**
408  * ttm_bo_unlock_delayed_workqueue
409  *
410  * Allows the delayed workqueue to run.
411  */
412 extern void ttm_bo_unlock_delayed_workqueue(struct ttm_bo_device *bdev,
413 					    int resched);
414 
415 /**
416  * ttm_bo_synccpu_write_grab
417  *
418  * @bo: The buffer object:
419  * @no_wait: Return immediately if buffer is busy.
420  *
421  * Synchronizes a buffer object for CPU RW access. This means
422  * command submission that affects the buffer will return -EBUSY
423  * until ttm_bo_synccpu_write_release is called.
424  *
425  * Returns
426  * -EBUSY if the buffer is busy and no_wait is true.
427  * -ERESTARTSYS if interrupted by a signal.
428  */
429 extern int
430 ttm_bo_synccpu_write_grab(struct ttm_buffer_object *bo, bool no_wait);
431 
432 /**
433  * ttm_bo_synccpu_write_release:
434  *
435  * @bo : The buffer object.
436  *
437  * Releases a synccpu lock.
438  */
439 extern void ttm_bo_synccpu_write_release(struct ttm_buffer_object *bo);
440 
441 /**
442  * ttm_bo_acc_size
443  *
444  * @bdev: Pointer to a ttm_bo_device struct.
445  * @bo_size: size of the buffer object in byte.
446  * @struct_size: size of the structure holding buffer object datas
447  *
448  * Returns size to account for a buffer object
449  */
450 size_t ttm_bo_acc_size(struct ttm_bo_device *bdev,
451 		       unsigned long bo_size,
452 		       unsigned struct_size);
453 size_t ttm_bo_dma_acc_size(struct ttm_bo_device *bdev,
454 			   unsigned long bo_size,
455 			   unsigned struct_size);
456 
457 /**
458  * ttm_bo_init
459  *
460  * @bdev: Pointer to a ttm_bo_device struct.
461  * @bo: Pointer to a ttm_buffer_object to be initialized.
462  * @size: Requested size of buffer object.
463  * @type: Requested type of buffer object.
464  * @flags: Initial placement flags.
465  * @page_alignment: Data alignment in pages.
466  * @interruptible: If needing to sleep to wait for GPU resources,
467  * sleep interruptible.
468  * @persistent_swap_storage: Usually the swap storage is deleted for buffers
469  * pinned in physical memory. If this behaviour is not desired, this member
470  * holds a pointer to a persistent shmem object. Typically, this would
471  * point to the shmem object backing a GEM object if TTM is used to back a
472  * GEM user interface.
473  * @acc_size: Accounted size for this object.
474  * @destroy: Destroy function. Use NULL for kfree().
475  *
476  * This function initializes a pre-allocated struct ttm_buffer_object.
477  * As this object may be part of a larger structure, this function,
478  * together with the @destroy function,
479  * enables driver-specific objects derived from a ttm_buffer_object.
480  * On successful return, the object kref and list_kref are set to 1.
481  * If a failure occurs, the function will call the @destroy function, or
482  * kfree() if @destroy is NULL. Thus, after a failure, dereferencing @bo is
483  * illegal and will likely cause memory corruption.
484  *
485  * Returns
486  * -ENOMEM: Out of memory.
487  * -EINVAL: Invalid placement flags.
488  * -ERESTARTSYS: Interrupted by signal while sleeping waiting for resources.
489  */
490 
491 extern int ttm_bo_init(struct ttm_bo_device *bdev,
492 			struct ttm_buffer_object *bo,
493 			unsigned long size,
494 			enum ttm_bo_type type,
495 			struct ttm_placement *placement,
496 			uint32_t page_alignment,
497 			bool interrubtible,
498 			struct vm_object *persistent_swap_storage,
499 			size_t acc_size,
500 			struct sg_table *sg,
501 			void (*destroy) (struct ttm_buffer_object *));
502 
503 /**
504  * ttm_bo_synccpu_object_init
505  *
506  * @bdev: Pointer to a ttm_bo_device struct.
507  * @bo: Pointer to a ttm_buffer_object to be initialized.
508  * @size: Requested size of buffer object.
509  * @type: Requested type of buffer object.
510  * @flags: Initial placement flags.
511  * @page_alignment: Data alignment in pages.
512  * @interruptible: If needing to sleep while waiting for GPU resources,
513  * sleep interruptible.
514  * @persistent_swap_storage: Usually the swap storage is deleted for buffers
515  * pinned in physical memory. If this behaviour is not desired, this member
516  * holds a pointer to a persistent shmem object. Typically, this would
517  * point to the shmem object backing a GEM object if TTM is used to back a
518  * GEM user interface.
519  * @p_bo: On successful completion *p_bo points to the created object.
520  *
521  * This function allocates a ttm_buffer_object, and then calls ttm_bo_init
522  * on that object. The destroy function is set to kfree().
523  * Returns
524  * -ENOMEM: Out of memory.
525  * -EINVAL: Invalid placement flags.
526  * -ERESTARTSYS: Interrupted by signal while waiting for resources.
527  */
528 
529 extern int ttm_bo_create(struct ttm_bo_device *bdev,
530 				unsigned long size,
531 				enum ttm_bo_type type,
532 				struct ttm_placement *placement,
533 				uint32_t page_alignment,
534 				bool interruptible,
535 				struct vm_object *persistent_swap_storage,
536 				struct ttm_buffer_object **p_bo);
537 
538 /**
539  * ttm_bo_check_placement
540  *
541  * @bo:		the buffer object.
542  * @placement:	placements
543  *
544  * Performs minimal validity checking on an intended change of
545  * placement flags.
546  * Returns
547  * -EINVAL: Intended change is invalid or not allowed.
548  */
549 extern int ttm_bo_check_placement(struct ttm_buffer_object *bo,
550 					struct ttm_placement *placement);
551 
552 /**
553  * ttm_bo_init_mm
554  *
555  * @bdev: Pointer to a ttm_bo_device struct.
556  * @mem_type: The memory type.
557  * @p_size: size managed area in pages.
558  *
559  * Initialize a manager for a given memory type.
560  * Note: if part of driver firstopen, it must be protected from a
561  * potentially racing lastclose.
562  * Returns:
563  * -EINVAL: invalid size or memory type.
564  * -ENOMEM: Not enough memory.
565  * May also return driver-specified errors.
566  */
567 
568 extern int ttm_bo_init_mm(struct ttm_bo_device *bdev, unsigned type,
569 				unsigned long p_size);
570 /**
571  * ttm_bo_clean_mm
572  *
573  * @bdev: Pointer to a ttm_bo_device struct.
574  * @mem_type: The memory type.
575  *
576  * Take down a manager for a given memory type after first walking
577  * the LRU list to evict any buffers left alive.
578  *
579  * Normally, this function is part of lastclose() or unload(), and at that
580  * point there shouldn't be any buffers left created by user-space, since
581  * there should've been removed by the file descriptor release() method.
582  * However, before this function is run, make sure to signal all sync objects,
583  * and verify that the delayed delete queue is empty. The driver must also
584  * make sure that there are no NO_EVICT buffers present in this memory type
585  * when the call is made.
586  *
587  * If this function is part of a VT switch, the caller must make sure that
588  * there are no appications currently validating buffers before this
589  * function is called. The caller can do that by first taking the
590  * struct ttm_bo_device::ttm_lock in write mode.
591  *
592  * Returns:
593  * -EINVAL: invalid or uninitialized memory type.
594  * -EBUSY: There are still buffers left in this memory type.
595  */
596 
597 extern int ttm_bo_clean_mm(struct ttm_bo_device *bdev, unsigned mem_type);
598 
599 /**
600  * ttm_bo_evict_mm
601  *
602  * @bdev: Pointer to a ttm_bo_device struct.
603  * @mem_type: The memory type.
604  *
605  * Evicts all buffers on the lru list of the memory type.
606  * This is normally part of a VT switch or an
607  * out-of-memory-space-due-to-fragmentation handler.
608  * The caller must make sure that there are no other processes
609  * currently validating buffers, and can do that by taking the
610  * struct ttm_bo_device::ttm_lock in write mode.
611  *
612  * Returns:
613  * -EINVAL: Invalid or uninitialized memory type.
614  * -ERESTARTSYS: The call was interrupted by a signal while waiting to
615  * evict a buffer.
616  */
617 
618 extern int ttm_bo_evict_mm(struct ttm_bo_device *bdev, unsigned mem_type);
619 
620 /**
621  * ttm_kmap_obj_virtual
622  *
623  * @map: A struct ttm_bo_kmap_obj returned from ttm_bo_kmap.
624  * @is_iomem: Pointer to an integer that on return indicates 1 if the
625  * virtual map is io memory, 0 if normal memory.
626  *
627  * Returns the virtual address of a buffer object area mapped by ttm_bo_kmap.
628  * If *is_iomem is 1 on return, the virtual address points to an io memory area,
629  * that should strictly be accessed by the iowriteXX() and similar functions.
630  */
631 
632 static inline void *ttm_kmap_obj_virtual(struct ttm_bo_kmap_obj *map,
633 					 bool *is_iomem)
634 {
635 	*is_iomem = !!(map->bo_kmap_type & TTM_BO_MAP_IOMEM_MASK);
636 	return map->virtual;
637 }
638 
639 /**
640  * ttm_bo_kmap
641  *
642  * @bo: The buffer object.
643  * @start_page: The first page to map.
644  * @num_pages: Number of pages to map.
645  * @map: pointer to a struct ttm_bo_kmap_obj representing the map.
646  *
647  * Sets up a kernel virtual mapping, using ioremap, vmap or kmap to the
648  * data in the buffer object. The ttm_kmap_obj_virtual function can then be
649  * used to obtain a virtual address to the data.
650  *
651  * Returns
652  * -ENOMEM: Out of memory.
653  * -EINVAL: Invalid range.
654  */
655 
656 extern int ttm_bo_kmap(struct ttm_buffer_object *bo, unsigned long start_page,
657 		       unsigned long num_pages, struct ttm_bo_kmap_obj *map);
658 
659 /**
660  * ttm_bo_kunmap
661  *
662  * @map: Object describing the map to unmap.
663  *
664  * Unmaps a kernel map set up by ttm_bo_kmap.
665  */
666 
667 extern void ttm_bo_kunmap(struct ttm_bo_kmap_obj *map);
668 
669 /**
670  * ttm_fbdev_mmap - mmap fbdev memory backed by a ttm buffer object.
671  *
672  * @vma:       vma as input from the fbdev mmap method.
673  * @bo:        The bo backing the address space. The address space will
674  * have the same size as the bo, and start at offset 0.
675  *
676  * This function is intended to be called by the fbdev mmap method
677  * if the fbdev address space is to be backed by a bo.
678  */
679 
680 /* XXXKIB
681 extern int ttm_fbdev_mmap(struct vm_area_struct *vma,
682 			  struct ttm_buffer_object *bo);
683 */
684 /**
685  * ttm_bo_mmap - mmap out of the ttm device address space.
686  *
687  * @filp:      filp as input from the mmap method.
688  * @vma:       vma as input from the mmap method.
689  * @bdev:      Pointer to the ttm_bo_device with the address space manager.
690  *
691  * This function is intended to be called by the device mmap method.
692  * if the device address space is to be backed by the bo manager.
693  */
694 /* XXXKIB
695 extern int ttm_bo_mmap(struct file *filp, struct vm_area_struct *vma,
696 		       struct ttm_bo_device *bdev);
697 */
698 /**
699  * ttm_bo_io
700  *
701  * @bdev:      Pointer to the struct ttm_bo_device.
702  * @filp:      Pointer to the struct file attempting to read / write.
703  * @wbuf:      User-space pointer to address of buffer to write. NULL on read.
704  * @rbuf:      User-space pointer to address of buffer to read into.
705  * Null on write.
706  * @count:     Number of bytes to read / write.
707  * @f_pos:     Pointer to current file position.
708  * @write:     1 for read, 0 for write.
709  *
710  * This function implements read / write into ttm buffer objects, and is
711  * intended to
712  * be called from the fops::read and fops::write method.
713  * Returns:
714  * See man (2) write, man(2) read. In particular,
715  * the function may return -ERESTARTSYS if
716  * interrupted by a signal.
717  */
718 
719 extern ssize_t ttm_bo_io(struct ttm_bo_device *bdev, struct file *filp,
720 			 const char *wbuf, char *rbuf,
721 			 size_t count, off_t *f_pos, bool write);
722 
723 extern void ttm_bo_swapout_all(struct ttm_bo_device *bdev);
724 
725 /**
726  * ttm_bo_is_reserved - return an indication if a ttm buffer object is reserved
727  *
728  * @bo:     The buffer object to check.
729  *
730  * This function returns an indication if a bo is reserved or not, and should
731  * only be used to print an error when it is not from incorrect api usage, since
732  * there's no guarantee that it is the caller that is holding the reservation.
733  */
734 static inline bool ttm_bo_is_reserved(struct ttm_buffer_object *bo)
735 {
736 	return atomic_read(&bo->reserved);
737 }
738 
739 #endif
740