videobuf2-dma-contig.c

  1/*
  2 * videobuf2-dma-contig.c - DMA contig memory allocator for videobuf2
  3 *
  4 * Copyright (C) 2010 Samsung Electronics
  5 *
  6 * Author: Pawel Osciak <pawel@osciak.com>
  7 *
  8 * This program is free software; you can redistribute it and/or modify
  9 * it under the terms of the GNU General Public License as published by
 10 * the Free Software Foundation.
 11 */
 12
 13#include <linux/dma-buf.h>
 14#include <linux/module.h>
 15#include <linux/refcount.h>
 16#include <linux/scatterlist.h>
 17#include <linux/sched.h>
 18#include <linux/slab.h>
 19#include <linux/dma-mapping.h>
 20#include <linux/highmem.h>
 21
 22#include <media/videobuf2-v4l2.h>
 23#include <media/videobuf2-dma-contig.h>
 24#include <media/videobuf2-memops.h>
 25
 26struct vb2_dc_buf {
 27	struct device			*dev;
 28	void				*vaddr;
 29	unsigned long			size;
 30	void				*cookie;
 31	dma_addr_t			dma_addr;
 32	unsigned long			attrs;
 33	enum dma_data_direction		dma_dir;
 34	struct sg_table			*dma_sgt;
 35	struct frame_vector		*vec;
 36
 37	/* MMAP related */
 38	struct vb2_vmarea_handler	handler;
 39	refcount_t			refcount;
 40	struct sg_table			*sgt_base;
 41
 42	/* DMABUF related */
 43	struct dma_buf_attachment	*db_attach;
 44
 45	struct vb2_buffer		*vb;
 46	bool				non_coherent_mem;
 47};
 48
 49/*********************************************/
 50/*        scatterlist table functions        */
 51/*********************************************/
 52
 53static unsigned long vb2_dc_get_contiguous_size(struct sg_table *sgt)
 54{
 55	struct scatterlist *s;
 56	dma_addr_t expected = sg_dma_address(sgt->sgl);
 57	unsigned int i;
 58	unsigned long size = 0;
 59
 60	for_each_sgtable_dma_sg(sgt, s, i) {
 61		if (sg_dma_address(s) != expected)
 62			break;
 63		expected += sg_dma_len(s);
 64		size += sg_dma_len(s);
 65	}
 66	return size;
 67}
 68
 69/*********************************************/
 70/*         callbacks for all buffers         */
 71/*********************************************/
 72
 73static void *vb2_dc_cookie(struct vb2_buffer *vb, void *buf_priv)
 74{
 75	struct vb2_dc_buf *buf = buf_priv;
 76
 77	return &buf->dma_addr;
 78}
 79
 80/*
 81 * This function may fail if:
 82 *
 83 * - dma_buf_vmap() fails
 84 *   E.g. due to lack of virtual mapping address space, or due to
 85 *   dmabuf->ops misconfiguration.
 86 *
 87 * - dma_vmap_noncontiguous() fails
 88 *   For instance, when requested buffer size is larger than totalram_pages().
 89 *   Relevant for buffers that use non-coherent memory.
 90 *
 91 * - Queue DMA attrs have DMA_ATTR_NO_KERNEL_MAPPING set
 92 *   Relevant for buffers that use coherent memory.
 93 */
 94static void *vb2_dc_vaddr(struct vb2_buffer *vb, void *buf_priv)
 95{
 96	struct vb2_dc_buf *buf = buf_priv;
 97
 98	if (buf->vaddr)
 99		return buf->vaddr;
100
101	if (buf->db_attach) {
102		struct iosys_map map;
103
104		if (!dma_buf_vmap_unlocked(buf->db_attach->dmabuf, &map))
105			buf->vaddr = map.vaddr;
106
107		return buf->vaddr;
108	}
109
110	if (buf->non_coherent_mem)
111		buf->vaddr = dma_vmap_noncontiguous(buf->dev, buf->size,
112						    buf->dma_sgt);
113	return buf->vaddr;
114}
115
116static unsigned int vb2_dc_num_users(void *buf_priv)
117{
118	struct vb2_dc_buf *buf = buf_priv;
119
120	return refcount_read(&buf->refcount);
121}
122
123static void vb2_dc_prepare(void *buf_priv)
124{
125	struct vb2_dc_buf *buf = buf_priv;
126	struct sg_table *sgt = buf->dma_sgt;
127
128	/* This takes care of DMABUF and user-enforced cache sync hint */
129	if (buf->vb->skip_cache_sync_on_prepare)
130		return;
131
132	if (!buf->non_coherent_mem)
133		return;
134
135	/* Non-coherent MMAP only */
136	if (buf->vaddr)
137		flush_kernel_vmap_range(buf->vaddr, buf->size);
138
139	/* For both USERPTR and non-coherent MMAP */
140	dma_sync_sgtable_for_device(buf->dev, sgt, buf->dma_dir);
141}
142
143static void vb2_dc_finish(void *buf_priv)
144{
145	struct vb2_dc_buf *buf = buf_priv;
146	struct sg_table *sgt = buf->dma_sgt;
147
148	/* This takes care of DMABUF and user-enforced cache sync hint */
149	if (buf->vb->skip_cache_sync_on_finish)
150		return;
151
152	if (!buf->non_coherent_mem)
153		return;
154
155	/* Non-coherent MMAP only */
156	if (buf->vaddr)
157		invalidate_kernel_vmap_range(buf->vaddr, buf->size);
158
159	/* For both USERPTR and non-coherent MMAP */
160	dma_sync_sgtable_for_cpu(buf->dev, sgt, buf->dma_dir);
161}
162
163/*********************************************/
164/*        callbacks for MMAP buffers         */
165/*********************************************/
166
167static void vb2_dc_put(void *buf_priv)
168{
169	struct vb2_dc_buf *buf = buf_priv;
170
171	if (!refcount_dec_and_test(&buf->refcount))
172		return;
173
174	if (buf->non_coherent_mem) {
175		if (buf->vaddr)
176			dma_vunmap_noncontiguous(buf->dev, buf->vaddr);
177		dma_free_noncontiguous(buf->dev, buf->size,
178				       buf->dma_sgt, buf->dma_dir);
179	} else {
180		if (buf->sgt_base) {
181			sg_free_table(buf->sgt_base);
182			kfree(buf->sgt_base);
183		}
184		dma_free_attrs(buf->dev, buf->size, buf->cookie,
185			       buf->dma_addr, buf->attrs);
186	}
187	put_device(buf->dev);
188	kfree(buf);
189}
190
191static int vb2_dc_alloc_coherent(struct vb2_dc_buf *buf)
192{
193	struct vb2_queue *q = buf->vb->vb2_queue;
194
195	buf->cookie = dma_alloc_attrs(buf->dev,
196				      buf->size,
197				      &buf->dma_addr,
198				      GFP_KERNEL | q->gfp_flags,
199				      buf->attrs);
200	if (!buf->cookie)
201		return -ENOMEM;
202
203	if (q->dma_attrs & DMA_ATTR_NO_KERNEL_MAPPING)
204		return 0;
205
206	buf->vaddr = buf->cookie;
207	return 0;
208}
209
210static int vb2_dc_alloc_non_coherent(struct vb2_dc_buf *buf)
211{
212	struct vb2_queue *q = buf->vb->vb2_queue;
213
214	buf->dma_sgt = dma_alloc_noncontiguous(buf->dev,
215					       buf->size,
216					       buf->dma_dir,
217					       GFP_KERNEL | q->gfp_flags,
218					       buf->attrs);
219	if (!buf->dma_sgt)
220		return -ENOMEM;
221
222	buf->dma_addr = sg_dma_address(buf->dma_sgt->sgl);
223
224	/*
225	 * For non-coherent buffers the kernel mapping is created on demand
226	 * in vb2_dc_vaddr().
227	 */
228	return 0;
229}
230
231static void *vb2_dc_alloc(struct vb2_buffer *vb,
232			  struct device *dev,
233			  unsigned long size)
234{
235	struct vb2_dc_buf *buf;
236	int ret;
237
238	if (WARN_ON(!dev))
239		return ERR_PTR(-EINVAL);
240
241	buf = kzalloc(sizeof *buf, GFP_KERNEL);
242	if (!buf)
243		return ERR_PTR(-ENOMEM);
244
245	buf->attrs = vb->vb2_queue->dma_attrs;
246	buf->dma_dir = vb->vb2_queue->dma_dir;
247	buf->vb = vb;
248	buf->non_coherent_mem = vb->vb2_queue->non_coherent_mem;
249
250	buf->size = size;
251	/* Prevent the device from being released while the buffer is used */
252	buf->dev = get_device(dev);
253
254	if (buf->non_coherent_mem)
255		ret = vb2_dc_alloc_non_coherent(buf);
256	else
257		ret = vb2_dc_alloc_coherent(buf);
258
259	if (ret) {
260		dev_err(dev, "dma alloc of size %lu failed\n", size);
261		put_device(buf->dev);
262		kfree(buf);
263		return ERR_PTR(-ENOMEM);
264	}
265
266	buf->handler.refcount = &buf->refcount;
267	buf->handler.put = vb2_dc_put;
268	buf->handler.arg = buf;
269
270	refcount_set(&buf->refcount, 1);
271
272	return buf;
273}
274
275static int vb2_dc_mmap(void *buf_priv, struct vm_area_struct *vma)
276{
277	struct vb2_dc_buf *buf = buf_priv;
278	int ret;
279
280	if (!buf) {
281		printk(KERN_ERR "No buffer to map\n");
282		return -EINVAL;
283	}
284
285	if (buf->non_coherent_mem)
286		ret = dma_mmap_noncontiguous(buf->dev, vma, buf->size,
287					     buf->dma_sgt);
288	else
289		ret = dma_mmap_attrs(buf->dev, vma, buf->cookie, buf->dma_addr,
290				     buf->size, buf->attrs);
291	if (ret) {
292		pr_err("Remapping memory failed, error: %d\n", ret);
293		return ret;
294	}
295
296	vm_flags_set(vma, VM_DONTEXPAND | VM_DONTDUMP);
297	vma->vm_private_data	= &buf->handler;
298	vma->vm_ops		= &vb2_common_vm_ops;
299
300	vma->vm_ops->open(vma);
301
302	pr_debug("%s: mapped dma addr 0x%08lx at 0x%08lx, size %lu\n",
303		 __func__, (unsigned long)buf->dma_addr, vma->vm_start,
304		 buf->size);
305
306	return 0;
307}
308
309/*********************************************/
310/*         DMABUF ops for exporters          */
311/*********************************************/
312
313struct vb2_dc_attachment {
314	struct sg_table sgt;
315	enum dma_data_direction dma_dir;
316};
317
318static int vb2_dc_dmabuf_ops_attach(struct dma_buf *dbuf,
319	struct dma_buf_attachment *dbuf_attach)
320{
321	struct vb2_dc_attachment *attach;
322	unsigned int i;
323	struct scatterlist *rd, *wr;
324	struct sg_table *sgt;
325	struct vb2_dc_buf *buf = dbuf->priv;
326	int ret;
327
328	attach = kzalloc(sizeof(*attach), GFP_KERNEL);
329	if (!attach)
330		return -ENOMEM;
331
332	sgt = &attach->sgt;
333	/* Copy the buf->base_sgt scatter list to the attachment, as we can't
334	 * map the same scatter list to multiple attachments at the same time.
335	 */
336	ret = sg_alloc_table(sgt, buf->sgt_base->orig_nents, GFP_KERNEL);
337	if (ret) {
338		kfree(attach);
339		return -ENOMEM;
340	}
341
342	rd = buf->sgt_base->sgl;
343	wr = sgt->sgl;
344	for (i = 0; i < sgt->orig_nents; ++i) {
345		sg_set_page(wr, sg_page(rd), rd->length, rd->offset);
346		rd = sg_next(rd);
347		wr = sg_next(wr);
348	}
349
350	attach->dma_dir = DMA_NONE;
351	dbuf_attach->priv = attach;
352
353	return 0;
354}
355
356static void vb2_dc_dmabuf_ops_detach(struct dma_buf *dbuf,
357	struct dma_buf_attachment *db_attach)
358{
359	struct vb2_dc_attachment *attach = db_attach->priv;
360	struct sg_table *sgt;
361
362	if (!attach)
363		return;
364
365	sgt = &attach->sgt;
366
367	/* release the scatterlist cache */
368	if (attach->dma_dir != DMA_NONE)
369		/*
370		 * Cache sync can be skipped here, as the vb2_dc memory is
371		 * allocated from device coherent memory, which means the
372		 * memory locations do not require any explicit cache
373		 * maintenance prior or after being used by the device.
374		 */
375		dma_unmap_sgtable(db_attach->dev, sgt, attach->dma_dir,
376				  DMA_ATTR_SKIP_CPU_SYNC);
377	sg_free_table(sgt);
378	kfree(attach);
379	db_attach->priv = NULL;
380}
381
382static struct sg_table *vb2_dc_dmabuf_ops_map(
383	struct dma_buf_attachment *db_attach, enum dma_data_direction dma_dir)
384{
385	struct vb2_dc_attachment *attach = db_attach->priv;
386	struct sg_table *sgt;
387
388	sgt = &attach->sgt;
389	/* return previously mapped sg table */
390	if (attach->dma_dir == dma_dir)
391		return sgt;
392
393	/* release any previous cache */
394	if (attach->dma_dir != DMA_NONE) {
395		dma_unmap_sgtable(db_attach->dev, sgt, attach->dma_dir,
396				  DMA_ATTR_SKIP_CPU_SYNC);
397		attach->dma_dir = DMA_NONE;
398	}
399
400	/*
401	 * mapping to the client with new direction, no cache sync
402	 * required see comment in vb2_dc_dmabuf_ops_detach()
403	 */
404	if (dma_map_sgtable(db_attach->dev, sgt, dma_dir,
405			    DMA_ATTR_SKIP_CPU_SYNC)) {
406		pr_err("failed to map scatterlist\n");
407		return ERR_PTR(-EIO);
408	}
409
410	attach->dma_dir = dma_dir;
411
412	return sgt;
413}
414
415static void vb2_dc_dmabuf_ops_unmap(struct dma_buf_attachment *db_attach,
416	struct sg_table *sgt, enum dma_data_direction dma_dir)
417{
418	/* nothing to be done here */
419}
420
421static void vb2_dc_dmabuf_ops_release(struct dma_buf *dbuf)
422{
423	/* drop reference obtained in vb2_dc_get_dmabuf */
424	vb2_dc_put(dbuf->priv);
425}
426
427static int
428vb2_dc_dmabuf_ops_begin_cpu_access(struct dma_buf *dbuf,
429				   enum dma_data_direction direction)
430{
431	return 0;
432}
433
434static int
435vb2_dc_dmabuf_ops_end_cpu_access(struct dma_buf *dbuf,
436				 enum dma_data_direction direction)
437{
438	return 0;
439}
440
441static int vb2_dc_dmabuf_ops_vmap(struct dma_buf *dbuf, struct iosys_map *map)
442{
443	struct vb2_dc_buf *buf;
444	void *vaddr;
445
446	buf = dbuf->priv;
447	vaddr = vb2_dc_vaddr(buf->vb, buf);
448	if (!vaddr)
449		return -EINVAL;
450
451	iosys_map_set_vaddr(map, vaddr);
452
453	return 0;
454}
455
456static int vb2_dc_dmabuf_ops_mmap(struct dma_buf *dbuf,
457	struct vm_area_struct *vma)
458{
459	return vb2_dc_mmap(dbuf->priv, vma);
460}
461
462static const struct dma_buf_ops vb2_dc_dmabuf_ops = {
463	.attach = vb2_dc_dmabuf_ops_attach,
464	.detach = vb2_dc_dmabuf_ops_detach,
465	.map_dma_buf = vb2_dc_dmabuf_ops_map,
466	.unmap_dma_buf = vb2_dc_dmabuf_ops_unmap,
467	.begin_cpu_access = vb2_dc_dmabuf_ops_begin_cpu_access,
468	.end_cpu_access = vb2_dc_dmabuf_ops_end_cpu_access,
469	.vmap = vb2_dc_dmabuf_ops_vmap,
470	.mmap = vb2_dc_dmabuf_ops_mmap,
471	.release = vb2_dc_dmabuf_ops_release,
472};
473
474static struct sg_table *vb2_dc_get_base_sgt(struct vb2_dc_buf *buf)
475{
476	int ret;
477	struct sg_table *sgt;
478
479	if (buf->non_coherent_mem)
480		return buf->dma_sgt;
481
482	sgt = kmalloc(sizeof(*sgt), GFP_KERNEL);
483	if (!sgt) {
484		dev_err(buf->dev, "failed to alloc sg table\n");
485		return NULL;
486	}
487
488	ret = dma_get_sgtable_attrs(buf->dev, sgt, buf->cookie, buf->dma_addr,
489		buf->size, buf->attrs);
490	if (ret < 0) {
491		dev_err(buf->dev, "failed to get scatterlist from DMA API\n");
492		kfree(sgt);
493		return NULL;
494	}
495
496	return sgt;
497}
498
499static struct dma_buf *vb2_dc_get_dmabuf(struct vb2_buffer *vb,
500					 void *buf_priv,
501					 unsigned long flags)
502{
503	struct vb2_dc_buf *buf = buf_priv;
504	struct dma_buf *dbuf;
505	DEFINE_DMA_BUF_EXPORT_INFO(exp_info);
506
507	exp_info.ops = &vb2_dc_dmabuf_ops;
508	exp_info.size = buf->size;
509	exp_info.flags = flags;
510	exp_info.priv = buf;
511
512	if (!buf->sgt_base)
513		buf->sgt_base = vb2_dc_get_base_sgt(buf);
514
515	if (WARN_ON(!buf->sgt_base))
516		return NULL;
517
518	dbuf = dma_buf_export(&exp_info);
519	if (IS_ERR(dbuf))
520		return NULL;
521
522	/* dmabuf keeps reference to vb2 buffer */
523	refcount_inc(&buf->refcount);
524
525	return dbuf;
526}
527
528/*********************************************/
529/*       callbacks for USERPTR buffers       */
530/*********************************************/
531
532static void vb2_dc_put_userptr(void *buf_priv)
533{
534	struct vb2_dc_buf *buf = buf_priv;
535	struct sg_table *sgt = buf->dma_sgt;
536	int i;
537	struct page **pages;
538
539	if (sgt) {
540		/*
541		 * No need to sync to CPU, it's already synced to the CPU
542		 * since the finish() memop will have been called before this.
543		 */
544		dma_unmap_sgtable(buf->dev, sgt, buf->dma_dir,
545				  DMA_ATTR_SKIP_CPU_SYNC);
546		if (buf->dma_dir == DMA_FROM_DEVICE ||
547				buf->dma_dir == DMA_BIDIRECTIONAL) {
548			pages = frame_vector_pages(buf->vec);
549			/* sgt should exist only if vector contains pages... */
550			if (!WARN_ON_ONCE(IS_ERR(pages)))
551				for (i = 0; i < frame_vector_count(buf->vec); i++)
552					set_page_dirty_lock(pages[i]);
553		}
554		sg_free_table(sgt);
555		kfree(sgt);
556	} else {
557		dma_unmap_resource(buf->dev, buf->dma_addr, buf->size,
558				   buf->dma_dir, 0);
559	}
560	vb2_destroy_framevec(buf->vec);
561	kfree(buf);
562}
563
564static void *vb2_dc_get_userptr(struct vb2_buffer *vb, struct device *dev,
565				unsigned long vaddr, unsigned long size)
566{
567	struct vb2_dc_buf *buf;
568	struct frame_vector *vec;
569	unsigned int offset;
570	int n_pages, i;
571	int ret = 0;
572	struct sg_table *sgt;
573	unsigned long contig_size;
574	unsigned long dma_align = dma_get_cache_alignment();
575
576	/* Only cache aligned DMA transfers are reliable */
577	if (!IS_ALIGNED(vaddr | size, dma_align)) {
578		pr_debug("user data must be aligned to %lu bytes\n", dma_align);
579		return ERR_PTR(-EINVAL);
580	}
581
582	if (!size) {
583		pr_debug("size is zero\n");
584		return ERR_PTR(-EINVAL);
585	}
586
587	if (WARN_ON(!dev))
588		return ERR_PTR(-EINVAL);
589
590	buf = kzalloc(sizeof *buf, GFP_KERNEL);
591	if (!buf)
592		return ERR_PTR(-ENOMEM);
593
594	buf->dev = dev;
595	buf->dma_dir = vb->vb2_queue->dma_dir;
596	buf->vb = vb;
597
598	offset = lower_32_bits(offset_in_page(vaddr));
599	vec = vb2_create_framevec(vaddr, size, buf->dma_dir == DMA_FROM_DEVICE ||
600					       buf->dma_dir == DMA_BIDIRECTIONAL);
601	if (IS_ERR(vec)) {
602		ret = PTR_ERR(vec);
603		goto fail_buf;
604	}
605	buf->vec = vec;
606	n_pages = frame_vector_count(vec);
607	ret = frame_vector_to_pages(vec);
608	if (ret < 0) {
609		unsigned long *nums = frame_vector_pfns(vec);
610
611		/*
612		 * Failed to convert to pages... Check the memory is physically
613		 * contiguous and use direct mapping
614		 */
615		for (i = 1; i < n_pages; i++)
616			if (nums[i-1] + 1 != nums[i])
617				goto fail_pfnvec;
618		buf->dma_addr = dma_map_resource(buf->dev,
619				__pfn_to_phys(nums[0]), size, buf->dma_dir, 0);
620		if (dma_mapping_error(buf->dev, buf->dma_addr)) {
621			ret = -ENOMEM;
622			goto fail_pfnvec;
623		}
624		goto out;
625	}
626
627	sgt = kzalloc(sizeof(*sgt), GFP_KERNEL);
628	if (!sgt) {
629		pr_err("failed to allocate sg table\n");
630		ret = -ENOMEM;
631		goto fail_pfnvec;
632	}
633
634	ret = sg_alloc_table_from_pages(sgt, frame_vector_pages(vec), n_pages,
635		offset, size, GFP_KERNEL);
636	if (ret) {
637		pr_err("failed to initialize sg table\n");
638		goto fail_sgt;
639	}
640
641	/*
642	 * No need to sync to the device, this will happen later when the
643	 * prepare() memop is called.
644	 */
645	if (dma_map_sgtable(buf->dev, sgt, buf->dma_dir,
646			    DMA_ATTR_SKIP_CPU_SYNC)) {
647		pr_err("failed to map scatterlist\n");
648		ret = -EIO;
649		goto fail_sgt_init;
650	}
651
652	contig_size = vb2_dc_get_contiguous_size(sgt);
653	if (contig_size < size) {
654		pr_err("contiguous mapping is too small %lu/%lu\n",
655			contig_size, size);
656		ret = -EFAULT;
657		goto fail_map_sg;
658	}
659
660	buf->dma_addr = sg_dma_address(sgt->sgl);
661	buf->dma_sgt = sgt;
662	buf->non_coherent_mem = 1;
663
664out:
665	buf->size = size;
666
667	return buf;
668
669fail_map_sg:
670	dma_unmap_sgtable(buf->dev, sgt, buf->dma_dir, DMA_ATTR_SKIP_CPU_SYNC);
671
672fail_sgt_init:
673	sg_free_table(sgt);
674
675fail_sgt:
676	kfree(sgt);
677
678fail_pfnvec:
679	vb2_destroy_framevec(vec);
680
681fail_buf:
682	kfree(buf);
683
684	return ERR_PTR(ret);
685}
686
687/*********************************************/
688/*       callbacks for DMABUF buffers        */
689/*********************************************/
690
691static int vb2_dc_map_dmabuf(void *mem_priv)
692{
693	struct vb2_dc_buf *buf = mem_priv;
694	struct sg_table *sgt;
695	unsigned long contig_size;
696
697	if (WARN_ON(!buf->db_attach)) {
698		pr_err("trying to pin a non attached buffer\n");
699		return -EINVAL;
700	}
701
702	if (WARN_ON(buf->dma_sgt)) {
703		pr_err("dmabuf buffer is already pinned\n");
704		return 0;
705	}
706
707	/* get the associated scatterlist for this buffer */
708	sgt = dma_buf_map_attachment_unlocked(buf->db_attach, buf->dma_dir);
709	if (IS_ERR(sgt)) {
710		pr_err("Error getting dmabuf scatterlist\n");
711		return -EINVAL;
712	}
713
714	/* checking if dmabuf is big enough to store contiguous chunk */
715	contig_size = vb2_dc_get_contiguous_size(sgt);
716	if (contig_size < buf->size) {
717		pr_err("contiguous chunk is too small %lu/%lu\n",
718		       contig_size, buf->size);
719		dma_buf_unmap_attachment_unlocked(buf->db_attach, sgt,
720						  buf->dma_dir);
721		return -EFAULT;
722	}
723
724	buf->dma_addr = sg_dma_address(sgt->sgl);
725	buf->dma_sgt = sgt;
726	buf->vaddr = NULL;
727
728	return 0;
729}
730
731static void vb2_dc_unmap_dmabuf(void *mem_priv)
732{
733	struct vb2_dc_buf *buf = mem_priv;
734	struct sg_table *sgt = buf->dma_sgt;
735	struct iosys_map map = IOSYS_MAP_INIT_VADDR(buf->vaddr);
736
737	if (WARN_ON(!buf->db_attach)) {
738		pr_err("trying to unpin a not attached buffer\n");
739		return;
740	}
741
742	if (WARN_ON(!sgt)) {
743		pr_err("dmabuf buffer is already unpinned\n");
744		return;
745	}
746
747	if (buf->vaddr) {
748		dma_buf_vunmap_unlocked(buf->db_attach->dmabuf, &map);
749		buf->vaddr = NULL;
750	}
751	dma_buf_unmap_attachment_unlocked(buf->db_attach, sgt, buf->dma_dir);
752
753	buf->dma_addr = 0;
754	buf->dma_sgt = NULL;
755}
756
757static void vb2_dc_detach_dmabuf(void *mem_priv)
758{
759	struct vb2_dc_buf *buf = mem_priv;
760
761	/* if vb2 works correctly you should never detach mapped buffer */
762	if (WARN_ON(buf->dma_addr))
763		vb2_dc_unmap_dmabuf(buf);
764
765	/* detach this attachment */
766	dma_buf_detach(buf->db_attach->dmabuf, buf->db_attach);
767	kfree(buf);
768}
769
770static void *vb2_dc_attach_dmabuf(struct vb2_buffer *vb, struct device *dev,
771				  struct dma_buf *dbuf, unsigned long size)
772{
773	struct vb2_dc_buf *buf;
774	struct dma_buf_attachment *dba;
775
776	if (dbuf->size < size)
777		return ERR_PTR(-EFAULT);
778
779	if (WARN_ON(!dev))
780		return ERR_PTR(-EINVAL);
781
782	buf = kzalloc(sizeof(*buf), GFP_KERNEL);
783	if (!buf)
784		return ERR_PTR(-ENOMEM);
785
786	buf->dev = dev;
787	buf->vb = vb;
788
789	/* create attachment for the dmabuf with the user device */
790	dba = dma_buf_attach(dbuf, buf->dev);
791	if (IS_ERR(dba)) {
792		pr_err("failed to attach dmabuf\n");
793		kfree(buf);
794		return dba;
795	}
796
797	buf->dma_dir = vb->vb2_queue->dma_dir;
798	buf->size = size;
799	buf->db_attach = dba;
800
801	return buf;
802}
803
804/*********************************************/
805/*       DMA CONTIG exported functions       */
806/*********************************************/
807
808const struct vb2_mem_ops vb2_dma_contig_memops = {
809	.alloc		= vb2_dc_alloc,
810	.put		= vb2_dc_put,
811	.get_dmabuf	= vb2_dc_get_dmabuf,
812	.cookie		= vb2_dc_cookie,
813	.vaddr		= vb2_dc_vaddr,
814	.mmap		= vb2_dc_mmap,
815	.get_userptr	= vb2_dc_get_userptr,
816	.put_userptr	= vb2_dc_put_userptr,
817	.prepare	= vb2_dc_prepare,
818	.finish		= vb2_dc_finish,
819	.map_dmabuf	= vb2_dc_map_dmabuf,
820	.unmap_dmabuf	= vb2_dc_unmap_dmabuf,
821	.attach_dmabuf	= vb2_dc_attach_dmabuf,
822	.detach_dmabuf	= vb2_dc_detach_dmabuf,
823	.num_users	= vb2_dc_num_users,
824};
825EXPORT_SYMBOL_GPL(vb2_dma_contig_memops);
826
827/**
828 * vb2_dma_contig_set_max_seg_size() - configure DMA max segment size
829 * @dev:	device for configuring DMA parameters
830 * @size:	size of DMA max segment size to set
831 *
832 * To allow mapping the scatter-list into a single chunk in the DMA
833 * address space, the device is required to have the DMA max segment
834 * size parameter set to a value larger than the buffer size. Otherwise,
835 * the DMA-mapping subsystem will split the mapping into max segment
836 * size chunks. This function sets the DMA max segment size
837 * parameter to let DMA-mapping map a buffer as a single chunk in DMA
838 * address space.
839 * This code assumes that the DMA-mapping subsystem will merge all
840 * scatterlist segments if this is really possible (for example when
841 * an IOMMU is available and enabled).
842 * Ideally, this parameter should be set by the generic bus code, but it
843 * is left with the default 64KiB value due to historical litmiations in
844 * other subsystems (like limited USB host drivers) and there no good
845 * place to set it to the proper value.
846 * This function should be called from the drivers, which are known to
847 * operate on platforms with IOMMU and provide access to shared buffers
848 * (either USERPTR or DMABUF). This should be done before initializing
849 * videobuf2 queue.
850 */
851int vb2_dma_contig_set_max_seg_size(struct device *dev, unsigned int size)
852{
853	if (!dev->dma_parms) {
854		dev_err(dev, "Failed to set max_seg_size: dma_parms is NULL\n");
855		return -ENODEV;
856	}
857	if (dma_get_max_seg_size(dev) < size)
858		dma_set_max_seg_size(dev, size);
859	return 0;
860}
861EXPORT_SYMBOL_GPL(vb2_dma_contig_set_max_seg_size);
862
863MODULE_DESCRIPTION("DMA-contig memory handling routines for videobuf2");
864MODULE_AUTHOR("Pawel Osciak <pawel@osciak.com>");
865MODULE_LICENSE("GPL");
866MODULE_IMPORT_NS("DMA_BUF");