xref: /openbmc/linux/drivers/gpu/drm/tegra/gem.c (revision aeb64ff3)
1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * NVIDIA Tegra DRM GEM helper functions
4  *
5  * Copyright (C) 2012 Sascha Hauer, Pengutronix
6  * Copyright (C) 2013-2015 NVIDIA CORPORATION, All rights reserved.
7  *
8  * Based on the GEM/CMA helpers
9  *
10  * Copyright (c) 2011 Samsung Electronics Co., Ltd.
11  */
12 
13 #include <linux/dma-buf.h>
14 #include <linux/iommu.h>
15 
16 #include <drm/drm_drv.h>
17 #include <drm/drm_prime.h>
18 #include <drm/tegra_drm.h>
19 
20 #include "drm.h"
21 #include "gem.h"
22 
23 static void tegra_bo_put(struct host1x_bo *bo)
24 {
25 	struct tegra_bo *obj = host1x_to_tegra_bo(bo);
26 
27 	drm_gem_object_put_unlocked(&obj->gem);
28 }
29 
30 /* XXX move this into lib/scatterlist.c? */
31 static int sg_alloc_table_from_sg(struct sg_table *sgt, struct scatterlist *sg,
32 				  unsigned int nents, gfp_t gfp_mask)
33 {
34 	struct scatterlist *dst;
35 	unsigned int i;
36 	int err;
37 
38 	err = sg_alloc_table(sgt, nents, gfp_mask);
39 	if (err < 0)
40 		return err;
41 
42 	dst = sgt->sgl;
43 
44 	for (i = 0; i < nents; i++) {
45 		sg_set_page(dst, sg_page(sg), sg->length, 0);
46 		dst = sg_next(dst);
47 		sg = sg_next(sg);
48 	}
49 
50 	return 0;
51 }
52 
53 static struct sg_table *tegra_bo_pin(struct device *dev, struct host1x_bo *bo,
54 				     dma_addr_t *phys)
55 {
56 	struct tegra_bo *obj = host1x_to_tegra_bo(bo);
57 	struct sg_table *sgt;
58 	int err;
59 
60 	/*
61 	 * If we've manually mapped the buffer object through the IOMMU, make
62 	 * sure to return the IOVA address of our mapping.
63 	 */
64 	if (phys && obj->mm) {
65 		*phys = obj->iova;
66 		return NULL;
67 	}
68 
69 	/*
70 	 * If we don't have a mapping for this buffer yet, return an SG table
71 	 * so that host1x can do the mapping for us via the DMA API.
72 	 */
73 	sgt = kzalloc(sizeof(*sgt), GFP_KERNEL);
74 	if (!sgt)
75 		return ERR_PTR(-ENOMEM);
76 
77 	if (obj->pages) {
78 		/*
79 		 * If the buffer object was allocated from the explicit IOMMU
80 		 * API code paths, construct an SG table from the pages.
81 		 */
82 		err = sg_alloc_table_from_pages(sgt, obj->pages, obj->num_pages,
83 						0, obj->gem.size, GFP_KERNEL);
84 		if (err < 0)
85 			goto free;
86 	} else if (obj->sgt) {
87 		/*
88 		 * If the buffer object already has an SG table but no pages
89 		 * were allocated for it, it means the buffer was imported and
90 		 * the SG table needs to be copied to avoid overwriting any
91 		 * other potential users of the original SG table.
92 		 */
93 		err = sg_alloc_table_from_sg(sgt, obj->sgt->sgl, obj->sgt->nents,
94 					     GFP_KERNEL);
95 		if (err < 0)
96 			goto free;
97 	} else {
98 		/*
99 		 * If the buffer object had no pages allocated and if it was
100 		 * not imported, it had to be allocated with the DMA API, so
101 		 * the DMA API helper can be used.
102 		 */
103 		err = dma_get_sgtable(dev, sgt, obj->vaddr, obj->iova,
104 				      obj->gem.size);
105 		if (err < 0)
106 			goto free;
107 	}
108 
109 	return sgt;
110 
111 free:
112 	kfree(sgt);
113 	return ERR_PTR(err);
114 }
115 
116 static void tegra_bo_unpin(struct device *dev, struct sg_table *sgt)
117 {
118 	if (sgt) {
119 		sg_free_table(sgt);
120 		kfree(sgt);
121 	}
122 }
123 
124 static void *tegra_bo_mmap(struct host1x_bo *bo)
125 {
126 	struct tegra_bo *obj = host1x_to_tegra_bo(bo);
127 
128 	if (obj->vaddr)
129 		return obj->vaddr;
130 	else if (obj->gem.import_attach)
131 		return dma_buf_vmap(obj->gem.import_attach->dmabuf);
132 	else
133 		return vmap(obj->pages, obj->num_pages, VM_MAP,
134 			    pgprot_writecombine(PAGE_KERNEL));
135 }
136 
137 static void tegra_bo_munmap(struct host1x_bo *bo, void *addr)
138 {
139 	struct tegra_bo *obj = host1x_to_tegra_bo(bo);
140 
141 	if (obj->vaddr)
142 		return;
143 	else if (obj->gem.import_attach)
144 		dma_buf_vunmap(obj->gem.import_attach->dmabuf, addr);
145 	else
146 		vunmap(addr);
147 }
148 
149 static void *tegra_bo_kmap(struct host1x_bo *bo, unsigned int page)
150 {
151 	struct tegra_bo *obj = host1x_to_tegra_bo(bo);
152 
153 	if (obj->vaddr)
154 		return obj->vaddr + page * PAGE_SIZE;
155 	else if (obj->gem.import_attach)
156 		return dma_buf_kmap(obj->gem.import_attach->dmabuf, page);
157 	else
158 		return vmap(obj->pages + page, 1, VM_MAP,
159 			    pgprot_writecombine(PAGE_KERNEL));
160 }
161 
162 static void tegra_bo_kunmap(struct host1x_bo *bo, unsigned int page,
163 			    void *addr)
164 {
165 	struct tegra_bo *obj = host1x_to_tegra_bo(bo);
166 
167 	if (obj->vaddr)
168 		return;
169 	else if (obj->gem.import_attach)
170 		dma_buf_kunmap(obj->gem.import_attach->dmabuf, page, addr);
171 	else
172 		vunmap(addr);
173 }
174 
175 static struct host1x_bo *tegra_bo_get(struct host1x_bo *bo)
176 {
177 	struct tegra_bo *obj = host1x_to_tegra_bo(bo);
178 
179 	drm_gem_object_get(&obj->gem);
180 
181 	return bo;
182 }
183 
184 static const struct host1x_bo_ops tegra_bo_ops = {
185 	.get = tegra_bo_get,
186 	.put = tegra_bo_put,
187 	.pin = tegra_bo_pin,
188 	.unpin = tegra_bo_unpin,
189 	.mmap = tegra_bo_mmap,
190 	.munmap = tegra_bo_munmap,
191 	.kmap = tegra_bo_kmap,
192 	.kunmap = tegra_bo_kunmap,
193 };
194 
195 static int tegra_bo_iommu_map(struct tegra_drm *tegra, struct tegra_bo *bo)
196 {
197 	int prot = IOMMU_READ | IOMMU_WRITE;
198 	int err;
199 
200 	if (bo->mm)
201 		return -EBUSY;
202 
203 	bo->mm = kzalloc(sizeof(*bo->mm), GFP_KERNEL);
204 	if (!bo->mm)
205 		return -ENOMEM;
206 
207 	mutex_lock(&tegra->mm_lock);
208 
209 	err = drm_mm_insert_node_generic(&tegra->mm,
210 					 bo->mm, bo->gem.size, PAGE_SIZE, 0, 0);
211 	if (err < 0) {
212 		dev_err(tegra->drm->dev, "out of I/O virtual memory: %d\n",
213 			err);
214 		goto unlock;
215 	}
216 
217 	bo->iova = bo->mm->start;
218 
219 	bo->size = iommu_map_sg(tegra->domain, bo->iova, bo->sgt->sgl,
220 				bo->sgt->nents, prot);
221 	if (!bo->size) {
222 		dev_err(tegra->drm->dev, "failed to map buffer\n");
223 		err = -ENOMEM;
224 		goto remove;
225 	}
226 
227 	mutex_unlock(&tegra->mm_lock);
228 
229 	return 0;
230 
231 remove:
232 	drm_mm_remove_node(bo->mm);
233 unlock:
234 	mutex_unlock(&tegra->mm_lock);
235 	kfree(bo->mm);
236 	return err;
237 }
238 
239 static int tegra_bo_iommu_unmap(struct tegra_drm *tegra, struct tegra_bo *bo)
240 {
241 	if (!bo->mm)
242 		return 0;
243 
244 	mutex_lock(&tegra->mm_lock);
245 	iommu_unmap(tegra->domain, bo->iova, bo->size);
246 	drm_mm_remove_node(bo->mm);
247 	mutex_unlock(&tegra->mm_lock);
248 
249 	kfree(bo->mm);
250 
251 	return 0;
252 }
253 
254 static struct tegra_bo *tegra_bo_alloc_object(struct drm_device *drm,
255 					      size_t size)
256 {
257 	struct tegra_bo *bo;
258 	int err;
259 
260 	bo = kzalloc(sizeof(*bo), GFP_KERNEL);
261 	if (!bo)
262 		return ERR_PTR(-ENOMEM);
263 
264 	host1x_bo_init(&bo->base, &tegra_bo_ops);
265 	size = round_up(size, PAGE_SIZE);
266 
267 	err = drm_gem_object_init(drm, &bo->gem, size);
268 	if (err < 0)
269 		goto free;
270 
271 	err = drm_gem_create_mmap_offset(&bo->gem);
272 	if (err < 0)
273 		goto release;
274 
275 	return bo;
276 
277 release:
278 	drm_gem_object_release(&bo->gem);
279 free:
280 	kfree(bo);
281 	return ERR_PTR(err);
282 }
283 
284 static void tegra_bo_free(struct drm_device *drm, struct tegra_bo *bo)
285 {
286 	if (bo->pages) {
287 		dma_unmap_sg(drm->dev, bo->sgt->sgl, bo->sgt->nents,
288 			     DMA_FROM_DEVICE);
289 		drm_gem_put_pages(&bo->gem, bo->pages, true, true);
290 		sg_free_table(bo->sgt);
291 		kfree(bo->sgt);
292 	} else if (bo->vaddr) {
293 		dma_free_wc(drm->dev, bo->gem.size, bo->vaddr, bo->iova);
294 	}
295 }
296 
297 static int tegra_bo_get_pages(struct drm_device *drm, struct tegra_bo *bo)
298 {
299 	int err;
300 
301 	bo->pages = drm_gem_get_pages(&bo->gem);
302 	if (IS_ERR(bo->pages))
303 		return PTR_ERR(bo->pages);
304 
305 	bo->num_pages = bo->gem.size >> PAGE_SHIFT;
306 
307 	bo->sgt = drm_prime_pages_to_sg(bo->pages, bo->num_pages);
308 	if (IS_ERR(bo->sgt)) {
309 		err = PTR_ERR(bo->sgt);
310 		goto put_pages;
311 	}
312 
313 	err = dma_map_sg(drm->dev, bo->sgt->sgl, bo->sgt->nents,
314 			 DMA_FROM_DEVICE);
315 	if (err == 0) {
316 		err = -EFAULT;
317 		goto free_sgt;
318 	}
319 
320 	return 0;
321 
322 free_sgt:
323 	sg_free_table(bo->sgt);
324 	kfree(bo->sgt);
325 put_pages:
326 	drm_gem_put_pages(&bo->gem, bo->pages, false, false);
327 	return err;
328 }
329 
330 static int tegra_bo_alloc(struct drm_device *drm, struct tegra_bo *bo)
331 {
332 	struct tegra_drm *tegra = drm->dev_private;
333 	int err;
334 
335 	if (tegra->domain) {
336 		err = tegra_bo_get_pages(drm, bo);
337 		if (err < 0)
338 			return err;
339 
340 		err = tegra_bo_iommu_map(tegra, bo);
341 		if (err < 0) {
342 			tegra_bo_free(drm, bo);
343 			return err;
344 		}
345 	} else {
346 		size_t size = bo->gem.size;
347 
348 		bo->vaddr = dma_alloc_wc(drm->dev, size, &bo->iova,
349 					 GFP_KERNEL | __GFP_NOWARN);
350 		if (!bo->vaddr) {
351 			dev_err(drm->dev,
352 				"failed to allocate buffer of size %zu\n",
353 				size);
354 			return -ENOMEM;
355 		}
356 	}
357 
358 	return 0;
359 }
360 
361 struct tegra_bo *tegra_bo_create(struct drm_device *drm, size_t size,
362 				 unsigned long flags)
363 {
364 	struct tegra_bo *bo;
365 	int err;
366 
367 	bo = tegra_bo_alloc_object(drm, size);
368 	if (IS_ERR(bo))
369 		return bo;
370 
371 	err = tegra_bo_alloc(drm, bo);
372 	if (err < 0)
373 		goto release;
374 
375 	if (flags & DRM_TEGRA_GEM_CREATE_TILED)
376 		bo->tiling.mode = TEGRA_BO_TILING_MODE_TILED;
377 
378 	if (flags & DRM_TEGRA_GEM_CREATE_BOTTOM_UP)
379 		bo->flags |= TEGRA_BO_BOTTOM_UP;
380 
381 	return bo;
382 
383 release:
384 	drm_gem_object_release(&bo->gem);
385 	kfree(bo);
386 	return ERR_PTR(err);
387 }
388 
389 struct tegra_bo *tegra_bo_create_with_handle(struct drm_file *file,
390 					     struct drm_device *drm,
391 					     size_t size,
392 					     unsigned long flags,
393 					     u32 *handle)
394 {
395 	struct tegra_bo *bo;
396 	int err;
397 
398 	bo = tegra_bo_create(drm, size, flags);
399 	if (IS_ERR(bo))
400 		return bo;
401 
402 	err = drm_gem_handle_create(file, &bo->gem, handle);
403 	if (err) {
404 		tegra_bo_free_object(&bo->gem);
405 		return ERR_PTR(err);
406 	}
407 
408 	drm_gem_object_put_unlocked(&bo->gem);
409 
410 	return bo;
411 }
412 
413 static struct tegra_bo *tegra_bo_import(struct drm_device *drm,
414 					struct dma_buf *buf)
415 {
416 	struct tegra_drm *tegra = drm->dev_private;
417 	struct dma_buf_attachment *attach;
418 	struct tegra_bo *bo;
419 	int err;
420 
421 	bo = tegra_bo_alloc_object(drm, buf->size);
422 	if (IS_ERR(bo))
423 		return bo;
424 
425 	attach = dma_buf_attach(buf, drm->dev);
426 	if (IS_ERR(attach)) {
427 		err = PTR_ERR(attach);
428 		goto free;
429 	}
430 
431 	get_dma_buf(buf);
432 
433 	bo->sgt = dma_buf_map_attachment(attach, DMA_TO_DEVICE);
434 	if (IS_ERR(bo->sgt)) {
435 		err = PTR_ERR(bo->sgt);
436 		goto detach;
437 	}
438 
439 	if (tegra->domain) {
440 		err = tegra_bo_iommu_map(tegra, bo);
441 		if (err < 0)
442 			goto detach;
443 	}
444 
445 	bo->gem.import_attach = attach;
446 
447 	return bo;
448 
449 detach:
450 	if (!IS_ERR_OR_NULL(bo->sgt))
451 		dma_buf_unmap_attachment(attach, bo->sgt, DMA_TO_DEVICE);
452 
453 	dma_buf_detach(buf, attach);
454 	dma_buf_put(buf);
455 free:
456 	drm_gem_object_release(&bo->gem);
457 	kfree(bo);
458 	return ERR_PTR(err);
459 }
460 
461 void tegra_bo_free_object(struct drm_gem_object *gem)
462 {
463 	struct tegra_drm *tegra = gem->dev->dev_private;
464 	struct tegra_bo *bo = to_tegra_bo(gem);
465 
466 	if (tegra->domain)
467 		tegra_bo_iommu_unmap(tegra, bo);
468 
469 	if (gem->import_attach) {
470 		dma_buf_unmap_attachment(gem->import_attach, bo->sgt,
471 					 DMA_TO_DEVICE);
472 		drm_prime_gem_destroy(gem, NULL);
473 	} else {
474 		tegra_bo_free(gem->dev, bo);
475 	}
476 
477 	drm_gem_object_release(gem);
478 	kfree(bo);
479 }
480 
481 int tegra_bo_dumb_create(struct drm_file *file, struct drm_device *drm,
482 			 struct drm_mode_create_dumb *args)
483 {
484 	unsigned int min_pitch = DIV_ROUND_UP(args->width * args->bpp, 8);
485 	struct tegra_drm *tegra = drm->dev_private;
486 	struct tegra_bo *bo;
487 
488 	args->pitch = round_up(min_pitch, tegra->pitch_align);
489 	args->size = args->pitch * args->height;
490 
491 	bo = tegra_bo_create_with_handle(file, drm, args->size, 0,
492 					 &args->handle);
493 	if (IS_ERR(bo))
494 		return PTR_ERR(bo);
495 
496 	return 0;
497 }
498 
499 static vm_fault_t tegra_bo_fault(struct vm_fault *vmf)
500 {
501 	struct vm_area_struct *vma = vmf->vma;
502 	struct drm_gem_object *gem = vma->vm_private_data;
503 	struct tegra_bo *bo = to_tegra_bo(gem);
504 	struct page *page;
505 	pgoff_t offset;
506 
507 	if (!bo->pages)
508 		return VM_FAULT_SIGBUS;
509 
510 	offset = (vmf->address - vma->vm_start) >> PAGE_SHIFT;
511 	page = bo->pages[offset];
512 
513 	return vmf_insert_page(vma, vmf->address, page);
514 }
515 
516 const struct vm_operations_struct tegra_bo_vm_ops = {
517 	.fault = tegra_bo_fault,
518 	.open = drm_gem_vm_open,
519 	.close = drm_gem_vm_close,
520 };
521 
522 int __tegra_gem_mmap(struct drm_gem_object *gem, struct vm_area_struct *vma)
523 {
524 	struct tegra_bo *bo = to_tegra_bo(gem);
525 
526 	if (!bo->pages) {
527 		unsigned long vm_pgoff = vma->vm_pgoff;
528 		int err;
529 
530 		/*
531 		 * Clear the VM_PFNMAP flag that was set by drm_gem_mmap(),
532 		 * and set the vm_pgoff (used as a fake buffer offset by DRM)
533 		 * to 0 as we want to map the whole buffer.
534 		 */
535 		vma->vm_flags &= ~VM_PFNMAP;
536 		vma->vm_pgoff = 0;
537 
538 		err = dma_mmap_wc(gem->dev->dev, vma, bo->vaddr, bo->iova,
539 				  gem->size);
540 		if (err < 0) {
541 			drm_gem_vm_close(vma);
542 			return err;
543 		}
544 
545 		vma->vm_pgoff = vm_pgoff;
546 	} else {
547 		pgprot_t prot = vm_get_page_prot(vma->vm_flags);
548 
549 		vma->vm_flags |= VM_MIXEDMAP;
550 		vma->vm_flags &= ~VM_PFNMAP;
551 
552 		vma->vm_page_prot = pgprot_writecombine(prot);
553 	}
554 
555 	return 0;
556 }
557 
558 int tegra_drm_mmap(struct file *file, struct vm_area_struct *vma)
559 {
560 	struct drm_gem_object *gem;
561 	int err;
562 
563 	err = drm_gem_mmap(file, vma);
564 	if (err < 0)
565 		return err;
566 
567 	gem = vma->vm_private_data;
568 
569 	return __tegra_gem_mmap(gem, vma);
570 }
571 
572 static struct sg_table *
573 tegra_gem_prime_map_dma_buf(struct dma_buf_attachment *attach,
574 			    enum dma_data_direction dir)
575 {
576 	struct drm_gem_object *gem = attach->dmabuf->priv;
577 	struct tegra_bo *bo = to_tegra_bo(gem);
578 	struct sg_table *sgt;
579 
580 	sgt = kmalloc(sizeof(*sgt), GFP_KERNEL);
581 	if (!sgt)
582 		return NULL;
583 
584 	if (bo->pages) {
585 		if (sg_alloc_table_from_pages(sgt, bo->pages, bo->num_pages,
586 					      0, gem->size, GFP_KERNEL) < 0)
587 			goto free;
588 	} else {
589 		if (dma_get_sgtable(attach->dev, sgt, bo->vaddr, bo->iova,
590 				    gem->size) < 0)
591 			goto free;
592 	}
593 
594 	if (dma_map_sg(attach->dev, sgt->sgl, sgt->nents, dir) == 0)
595 		goto free;
596 
597 	return sgt;
598 
599 free:
600 	sg_free_table(sgt);
601 	kfree(sgt);
602 	return NULL;
603 }
604 
605 static void tegra_gem_prime_unmap_dma_buf(struct dma_buf_attachment *attach,
606 					  struct sg_table *sgt,
607 					  enum dma_data_direction dir)
608 {
609 	struct drm_gem_object *gem = attach->dmabuf->priv;
610 	struct tegra_bo *bo = to_tegra_bo(gem);
611 
612 	if (bo->pages)
613 		dma_unmap_sg(attach->dev, sgt->sgl, sgt->nents, dir);
614 
615 	sg_free_table(sgt);
616 	kfree(sgt);
617 }
618 
619 static void tegra_gem_prime_release(struct dma_buf *buf)
620 {
621 	drm_gem_dmabuf_release(buf);
622 }
623 
624 static int tegra_gem_prime_begin_cpu_access(struct dma_buf *buf,
625 					    enum dma_data_direction direction)
626 {
627 	struct drm_gem_object *gem = buf->priv;
628 	struct tegra_bo *bo = to_tegra_bo(gem);
629 	struct drm_device *drm = gem->dev;
630 
631 	if (bo->pages)
632 		dma_sync_sg_for_cpu(drm->dev, bo->sgt->sgl, bo->sgt->nents,
633 				    DMA_FROM_DEVICE);
634 
635 	return 0;
636 }
637 
638 static int tegra_gem_prime_end_cpu_access(struct dma_buf *buf,
639 					  enum dma_data_direction direction)
640 {
641 	struct drm_gem_object *gem = buf->priv;
642 	struct tegra_bo *bo = to_tegra_bo(gem);
643 	struct drm_device *drm = gem->dev;
644 
645 	if (bo->pages)
646 		dma_sync_sg_for_device(drm->dev, bo->sgt->sgl, bo->sgt->nents,
647 				       DMA_TO_DEVICE);
648 
649 	return 0;
650 }
651 
652 static void *tegra_gem_prime_kmap(struct dma_buf *buf, unsigned long page)
653 {
654 	return NULL;
655 }
656 
657 static void tegra_gem_prime_kunmap(struct dma_buf *buf, unsigned long page,
658 				   void *addr)
659 {
660 }
661 
662 static int tegra_gem_prime_mmap(struct dma_buf *buf, struct vm_area_struct *vma)
663 {
664 	struct drm_gem_object *gem = buf->priv;
665 	int err;
666 
667 	err = drm_gem_mmap_obj(gem, gem->size, vma);
668 	if (err < 0)
669 		return err;
670 
671 	return __tegra_gem_mmap(gem, vma);
672 }
673 
674 static void *tegra_gem_prime_vmap(struct dma_buf *buf)
675 {
676 	struct drm_gem_object *gem = buf->priv;
677 	struct tegra_bo *bo = to_tegra_bo(gem);
678 
679 	return bo->vaddr;
680 }
681 
682 static void tegra_gem_prime_vunmap(struct dma_buf *buf, void *vaddr)
683 {
684 }
685 
686 static const struct dma_buf_ops tegra_gem_prime_dmabuf_ops = {
687 	.map_dma_buf = tegra_gem_prime_map_dma_buf,
688 	.unmap_dma_buf = tegra_gem_prime_unmap_dma_buf,
689 	.release = tegra_gem_prime_release,
690 	.begin_cpu_access = tegra_gem_prime_begin_cpu_access,
691 	.end_cpu_access = tegra_gem_prime_end_cpu_access,
692 	.map = tegra_gem_prime_kmap,
693 	.unmap = tegra_gem_prime_kunmap,
694 	.mmap = tegra_gem_prime_mmap,
695 	.vmap = tegra_gem_prime_vmap,
696 	.vunmap = tegra_gem_prime_vunmap,
697 };
698 
699 struct dma_buf *tegra_gem_prime_export(struct drm_gem_object *gem,
700 				       int flags)
701 {
702 	DEFINE_DMA_BUF_EXPORT_INFO(exp_info);
703 
704 	exp_info.exp_name = KBUILD_MODNAME;
705 	exp_info.owner = gem->dev->driver->fops->owner;
706 	exp_info.ops = &tegra_gem_prime_dmabuf_ops;
707 	exp_info.size = gem->size;
708 	exp_info.flags = flags;
709 	exp_info.priv = gem;
710 
711 	return drm_gem_dmabuf_export(gem->dev, &exp_info);
712 }
713 
714 struct drm_gem_object *tegra_gem_prime_import(struct drm_device *drm,
715 					      struct dma_buf *buf)
716 {
717 	struct tegra_bo *bo;
718 
719 	if (buf->ops == &tegra_gem_prime_dmabuf_ops) {
720 		struct drm_gem_object *gem = buf->priv;
721 
722 		if (gem->dev == drm) {
723 			drm_gem_object_get(gem);
724 			return gem;
725 		}
726 	}
727 
728 	bo = tegra_bo_import(drm, buf);
729 	if (IS_ERR(bo))
730 		return ERR_CAST(bo);
731 
732 	return &bo->gem;
733 }
734