1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * helper functions for SG DMA video4linux capture buffers
4 *
5 * The functions expect the hardware being able to scatter gather
6 * (i.e. the buffers are not linear in physical memory, but fragmented
7 * into PAGE_SIZE chunks).  They also assume the driver does not need
8 * to touch the video data.
9 *
10 * (c) 2007 Mauro Carvalho Chehab, <mchehab@kernel.org>
11 *
12 * Highly based on video-buf written originally by:
13 * (c) 2001,02 Gerd Knorr <kraxel@bytesex.org>
14 * (c) 2006 Mauro Carvalho Chehab, <mchehab@kernel.org>
15 * (c) 2006 Ted Walther and John Sokol
16 */
17
18#include <linux/init.h>
19#include <linux/module.h>
20#include <linux/moduleparam.h>
21#include <linux/sched/mm.h>
22#include <linux/slab.h>
23#include <linux/interrupt.h>
24#include <linux/pgtable.h>
25
26#include <linux/dma-mapping.h>
27#include <linux/vmalloc.h>
28#include <linux/pagemap.h>
29#include <linux/scatterlist.h>
30#include <asm/page.h>
31
32#include <media/videobuf-dma-sg.h>
33
34#define MAGIC_DMABUF 0x19721112
35#define MAGIC_SG_MEM 0x17890714
36
37#define MAGIC_CHECK(is, should)						\
38	if (unlikely((is) != (should))) {				\
39		printk(KERN_ERR "magic mismatch: %x (expected %x)\n",	\
40				is, should);				\
41		BUG();							\
42	}
43
44static int debug;
45module_param(debug, int, 0644);
46
47MODULE_DESCRIPTION("helper module to manage video4linux dma sg buffers");
48MODULE_AUTHOR("Mauro Carvalho Chehab <mchehab@kernel.org>");
49MODULE_LICENSE("GPL");
50
51#define dprintk(level, fmt, arg...)					\
52	if (debug >= level)						\
53		printk(KERN_DEBUG "vbuf-sg: " fmt , ## arg)
54
55/* --------------------------------------------------------------------- */
56
57/*
58 * Return a scatterlist for some page-aligned vmalloc()'ed memory
59 * block (NULL on errors).  Memory for the scatterlist is allocated
60 * using kmalloc.  The caller must free the memory.
61 */
62static struct scatterlist *videobuf_vmalloc_to_sg(unsigned char *virt,
63						  int nr_pages)
64{
65	struct scatterlist *sglist;
66	struct page *pg;
67	int i;
68
69	sglist = vzalloc(array_size(nr_pages, sizeof(*sglist)));
70	if (NULL == sglist)
71		return NULL;
72	sg_init_table(sglist, nr_pages);
73	for (i = 0; i < nr_pages; i++, virt += PAGE_SIZE) {
74		pg = vmalloc_to_page(virt);
75		if (NULL == pg)
76			goto err;
77		BUG_ON(PageHighMem(pg));
78		sg_set_page(&sglist[i], pg, PAGE_SIZE, 0);
79	}
80	return sglist;
81
82err:
83	vfree(sglist);
84	return NULL;
85}
86
87/*
88 * Return a scatterlist for a an array of userpages (NULL on errors).
89 * Memory for the scatterlist is allocated using kmalloc.  The caller
90 * must free the memory.
91 */
92static struct scatterlist *videobuf_pages_to_sg(struct page **pages,
93					int nr_pages, int offset, size_t size)
94{
95	struct scatterlist *sglist;
96	int i;
97
98	if (NULL == pages[0])
99		return NULL;
100	sglist = vmalloc(array_size(nr_pages, sizeof(*sglist)));
101	if (NULL == sglist)
102		return NULL;
103	sg_init_table(sglist, nr_pages);
104
105	if (PageHighMem(pages[0]))
106		/* DMA to highmem pages might not work */
107		goto highmem;
108	sg_set_page(&sglist[0], pages[0],
109			min_t(size_t, PAGE_SIZE - offset, size), offset);
110	size -= min_t(size_t, PAGE_SIZE - offset, size);
111	for (i = 1; i < nr_pages; i++) {
112		if (NULL == pages[i])
113			goto nopage;
114		if (PageHighMem(pages[i]))
115			goto highmem;
116		sg_set_page(&sglist[i], pages[i], min_t(size_t, PAGE_SIZE, size), 0);
117		size -= min_t(size_t, PAGE_SIZE, size);
118	}
119	return sglist;
120
121nopage:
122	dprintk(2, "sgl: oops - no page\n");
123	vfree(sglist);
124	return NULL;
125
126highmem:
127	dprintk(2, "sgl: oops - highmem page\n");
128	vfree(sglist);
129	return NULL;
130}
131
132/* --------------------------------------------------------------------- */
133
134struct videobuf_dmabuf *videobuf_to_dma(struct videobuf_buffer *buf)
135{
136	struct videobuf_dma_sg_memory *mem = buf->priv;
137	BUG_ON(!mem);
138
139	MAGIC_CHECK(mem->magic, MAGIC_SG_MEM);
140
141	return &mem->dma;
142}
143EXPORT_SYMBOL_GPL(videobuf_to_dma);
144
145static void videobuf_dma_init(struct videobuf_dmabuf *dma)
146{
147	memset(dma, 0, sizeof(*dma));
148	dma->magic = MAGIC_DMABUF;
149}
150
151static int videobuf_dma_init_user_locked(struct videobuf_dmabuf *dma,
152			int direction, unsigned long data, unsigned long size)
153{
154	unsigned long first, last;
155	int err, rw = 0;
156	unsigned int flags = FOLL_FORCE;
157
158	dma->direction = direction;
159	switch (dma->direction) {
160	case DMA_FROM_DEVICE:
161		rw = READ;
162		break;
163	case DMA_TO_DEVICE:
164		rw = WRITE;
165		break;
166	default:
167		BUG();
168	}
169
170	first = (data          & PAGE_MASK) >> PAGE_SHIFT;
171	last  = ((data+size-1) & PAGE_MASK) >> PAGE_SHIFT;
172	dma->offset = data & ~PAGE_MASK;
173	dma->size = size;
174	dma->nr_pages = last-first+1;
175	dma->pages = kmalloc_array(dma->nr_pages, sizeof(struct page *),
176				   GFP_KERNEL);
177	if (NULL == dma->pages)
178		return -ENOMEM;
179
180	if (rw == READ)
181		flags |= FOLL_WRITE;
182
183	dprintk(1, "init user [0x%lx+0x%lx => %lu pages]\n",
184		data, size, dma->nr_pages);
185
186	err = pin_user_pages(data & PAGE_MASK, dma->nr_pages,
187			     flags | FOLL_LONGTERM, dma->pages, NULL);
188
189	if (err != dma->nr_pages) {
190		dma->nr_pages = (err >= 0) ? err : 0;
191		dprintk(1, "pin_user_pages: err=%d [%lu]\n", err,
192			dma->nr_pages);
193		return err < 0 ? err : -EINVAL;
194	}
195	return 0;
196}
197
198static int videobuf_dma_init_user(struct videobuf_dmabuf *dma, int direction,
199			   unsigned long data, unsigned long size)
200{
201	int ret;
202
203	mmap_read_lock(current->mm);
204	ret = videobuf_dma_init_user_locked(dma, direction, data, size);
205	mmap_read_unlock(current->mm);
206
207	return ret;
208}
209
210static int videobuf_dma_init_kernel(struct videobuf_dmabuf *dma, int direction,
211				    unsigned long nr_pages)
212{
213	int i;
214
215	dprintk(1, "init kernel [%lu pages]\n", nr_pages);
216
217	dma->direction = direction;
218	dma->vaddr_pages = kcalloc(nr_pages, sizeof(*dma->vaddr_pages),
219				   GFP_KERNEL);
220	if (!dma->vaddr_pages)
221		return -ENOMEM;
222
223	dma->dma_addr = kcalloc(nr_pages, sizeof(*dma->dma_addr), GFP_KERNEL);
224	if (!dma->dma_addr) {
225		kfree(dma->vaddr_pages);
226		return -ENOMEM;
227	}
228	for (i = 0; i < nr_pages; i++) {
229		void *addr;
230
231		addr = dma_alloc_coherent(dma->dev, PAGE_SIZE,
232					  &(dma->dma_addr[i]), GFP_KERNEL);
233		if (addr == NULL)
234			goto out_free_pages;
235
236		dma->vaddr_pages[i] = virt_to_page(addr);
237	}
238	dma->vaddr = vmap(dma->vaddr_pages, nr_pages, VM_MAP | VM_IOREMAP,
239			  PAGE_KERNEL);
240	if (NULL == dma->vaddr) {
241		dprintk(1, "vmalloc_32(%lu pages) failed\n", nr_pages);
242		goto out_free_pages;
243	}
244
245	dprintk(1, "vmalloc is at addr %p, size=%lu\n",
246		dma->vaddr, nr_pages << PAGE_SHIFT);
247
248	memset(dma->vaddr, 0, nr_pages << PAGE_SHIFT);
249	dma->nr_pages = nr_pages;
250
251	return 0;
252out_free_pages:
253	while (i > 0) {
254		void *addr;
255
256		i--;
257		addr = page_address(dma->vaddr_pages[i]);
258		dma_free_coherent(dma->dev, PAGE_SIZE, addr, dma->dma_addr[i]);
259	}
260	kfree(dma->dma_addr);
261	dma->dma_addr = NULL;
262	kfree(dma->vaddr_pages);
263	dma->vaddr_pages = NULL;
264
265	return -ENOMEM;
266
267}
268
269static int videobuf_dma_init_overlay(struct videobuf_dmabuf *dma, int direction,
270			      dma_addr_t addr, unsigned long nr_pages)
271{
272	dprintk(1, "init overlay [%lu pages @ bus 0x%lx]\n",
273		nr_pages, (unsigned long)addr);
274	dma->direction = direction;
275
276	if (0 == addr)
277		return -EINVAL;
278
279	dma->bus_addr = addr;
280	dma->nr_pages = nr_pages;
281
282	return 0;
283}
284
285static int videobuf_dma_map(struct device *dev, struct videobuf_dmabuf *dma)
286{
287	MAGIC_CHECK(dma->magic, MAGIC_DMABUF);
288	BUG_ON(0 == dma->nr_pages);
289
290	if (dma->pages) {
291		dma->sglist = videobuf_pages_to_sg(dma->pages, dma->nr_pages,
292						   dma->offset, dma->size);
293	}
294	if (dma->vaddr) {
295		dma->sglist = videobuf_vmalloc_to_sg(dma->vaddr,
296						     dma->nr_pages);
297	}
298	if (dma->bus_addr) {
299		dma->sglist = vmalloc(sizeof(*dma->sglist));
300		if (NULL != dma->sglist) {
301			dma->sglen = 1;
302			sg_dma_address(&dma->sglist[0])	= dma->bus_addr
303							& PAGE_MASK;
304			dma->sglist[0].offset = dma->bus_addr & ~PAGE_MASK;
305			sg_dma_len(&dma->sglist[0]) = dma->nr_pages * PAGE_SIZE;
306		}
307	}
308	if (NULL == dma->sglist) {
309		dprintk(1, "scatterlist is NULL\n");
310		return -ENOMEM;
311	}
312	if (!dma->bus_addr) {
313		dma->sglen = dma_map_sg(dev, dma->sglist,
314					dma->nr_pages, dma->direction);
315		if (0 == dma->sglen) {
316			printk(KERN_WARNING
317			       "%s: videobuf_map_sg failed\n", __func__);
318			vfree(dma->sglist);
319			dma->sglist = NULL;
320			dma->sglen = 0;
321			return -ENOMEM;
322		}
323	}
324
325	return 0;
326}
327
328int videobuf_dma_unmap(struct device *dev, struct videobuf_dmabuf *dma)
329{
330	MAGIC_CHECK(dma->magic, MAGIC_DMABUF);
331
332	if (!dma->sglen)
333		return 0;
334
335	dma_unmap_sg(dev, dma->sglist, dma->nr_pages, dma->direction);
336
337	vfree(dma->sglist);
338	dma->sglist = NULL;
339	dma->sglen = 0;
340
341	return 0;
342}
343EXPORT_SYMBOL_GPL(videobuf_dma_unmap);
344
345int videobuf_dma_free(struct videobuf_dmabuf *dma)
346{
347	int i;
348	MAGIC_CHECK(dma->magic, MAGIC_DMABUF);
349	BUG_ON(dma->sglen);
350
351	if (dma->pages) {
352		unpin_user_pages_dirty_lock(dma->pages, dma->nr_pages,
353					    dma->direction == DMA_FROM_DEVICE);
354		kfree(dma->pages);
355		dma->pages = NULL;
356	}
357
358	if (dma->dma_addr) {
359		for (i = 0; i < dma->nr_pages; i++) {
360			void *addr;
361
362			addr = page_address(dma->vaddr_pages[i]);
363			dma_free_coherent(dma->dev, PAGE_SIZE, addr,
364					  dma->dma_addr[i]);
365		}
366		kfree(dma->dma_addr);
367		dma->dma_addr = NULL;
368		kfree(dma->vaddr_pages);
369		dma->vaddr_pages = NULL;
370		vunmap(dma->vaddr);
371		dma->vaddr = NULL;
372	}
373
374	if (dma->bus_addr)
375		dma->bus_addr = 0;
376	dma->direction = DMA_NONE;
377
378	return 0;
379}
380EXPORT_SYMBOL_GPL(videobuf_dma_free);
381
382/* --------------------------------------------------------------------- */
383
384static void videobuf_vm_open(struct vm_area_struct *vma)
385{
386	struct videobuf_mapping *map = vma->vm_private_data;
387
388	dprintk(2, "vm_open %p [count=%d,vma=%08lx-%08lx]\n", map,
389		map->count, vma->vm_start, vma->vm_end);
390
391	map->count++;
392}
393
394static void videobuf_vm_close(struct vm_area_struct *vma)
395{
396	struct videobuf_mapping *map = vma->vm_private_data;
397	struct videobuf_queue *q = map->q;
398	struct videobuf_dma_sg_memory *mem;
399	int i;
400
401	dprintk(2, "vm_close %p [count=%d,vma=%08lx-%08lx]\n", map,
402		map->count, vma->vm_start, vma->vm_end);
403
404	map->count--;
405	if (0 == map->count) {
406		dprintk(1, "munmap %p q=%p\n", map, q);
407		videobuf_queue_lock(q);
408		for (i = 0; i < VIDEO_MAX_FRAME; i++) {
409			if (NULL == q->bufs[i])
410				continue;
411			mem = q->bufs[i]->priv;
412			if (!mem)
413				continue;
414
415			MAGIC_CHECK(mem->magic, MAGIC_SG_MEM);
416
417			if (q->bufs[i]->map != map)
418				continue;
419			q->bufs[i]->map   = NULL;
420			q->bufs[i]->baddr = 0;
421			q->ops->buf_release(q, q->bufs[i]);
422		}
423		videobuf_queue_unlock(q);
424		kfree(map);
425	}
426	return;
427}
428
429/*
430 * Get a anonymous page for the mapping.  Make sure we can DMA to that
431 * memory location with 32bit PCI devices (i.e. don't use highmem for
432 * now ...).  Bounce buffers don't work very well for the data rates
433 * video capture has.
434 */
435static vm_fault_t videobuf_vm_fault(struct vm_fault *vmf)
436{
437	struct vm_area_struct *vma = vmf->vma;
438	struct page *page;
439
440	dprintk(3, "fault: fault @ %08lx [vma %08lx-%08lx]\n",
441		vmf->address, vma->vm_start, vma->vm_end);
442
443	page = alloc_page(GFP_USER | __GFP_DMA32);
444	if (!page)
445		return VM_FAULT_OOM;
446	clear_user_highpage(page, vmf->address);
447	vmf->page = page;
448
449	return 0;
450}
451
452static const struct vm_operations_struct videobuf_vm_ops = {
453	.open	= videobuf_vm_open,
454	.close	= videobuf_vm_close,
455	.fault	= videobuf_vm_fault,
456};
457
458/* ---------------------------------------------------------------------
459 * SG handlers for the generic methods
460 */
461
462/* Allocated area consists on 3 parts:
463	struct video_buffer
464	struct <driver>_buffer (cx88_buffer, saa7134_buf, ...)
465	struct videobuf_dma_sg_memory
466 */
467
468static struct videobuf_buffer *__videobuf_alloc_vb(size_t size)
469{
470	struct videobuf_dma_sg_memory *mem;
471	struct videobuf_buffer *vb;
472
473	vb = kzalloc(size + sizeof(*mem), GFP_KERNEL);
474	if (!vb)
475		return vb;
476
477	mem = vb->priv = ((char *)vb) + size;
478	mem->magic = MAGIC_SG_MEM;
479
480	videobuf_dma_init(&mem->dma);
481
482	dprintk(1, "%s: allocated at %p(%ld+%ld) & %p(%ld)\n",
483		__func__, vb, (long)sizeof(*vb), (long)size - sizeof(*vb),
484		mem, (long)sizeof(*mem));
485
486	return vb;
487}
488
489static void *__videobuf_to_vaddr(struct videobuf_buffer *buf)
490{
491	struct videobuf_dma_sg_memory *mem = buf->priv;
492	BUG_ON(!mem);
493
494	MAGIC_CHECK(mem->magic, MAGIC_SG_MEM);
495
496	return mem->dma.vaddr;
497}
498
499static int __videobuf_iolock(struct videobuf_queue *q,
500			     struct videobuf_buffer *vb,
501			     struct v4l2_framebuffer *fbuf)
502{
503	struct videobuf_dma_sg_memory *mem = vb->priv;
504	unsigned long pages;
505	dma_addr_t bus;
506	int err;
507
508	BUG_ON(!mem);
509
510	MAGIC_CHECK(mem->magic, MAGIC_SG_MEM);
511
512	if (!mem->dma.dev)
513		mem->dma.dev = q->dev;
514	else
515		WARN_ON(mem->dma.dev != q->dev);
516
517	switch (vb->memory) {
518	case V4L2_MEMORY_MMAP:
519	case V4L2_MEMORY_USERPTR:
520		if (0 == vb->baddr) {
521			/* no userspace addr -- kernel bounce buffer */
522			pages = PAGE_ALIGN(vb->size) >> PAGE_SHIFT;
523			err = videobuf_dma_init_kernel(&mem->dma,
524						       DMA_FROM_DEVICE,
525						       pages);
526			if (0 != err)
527				return err;
528		} else if (vb->memory == V4L2_MEMORY_USERPTR) {
529			/* dma directly to userspace */
530			err = videobuf_dma_init_user(&mem->dma,
531						     DMA_FROM_DEVICE,
532						     vb->baddr, vb->bsize);
533			if (0 != err)
534				return err;
535		} else {
536			/* NOTE: HACK: videobuf_iolock on V4L2_MEMORY_MMAP
537			buffers can only be called from videobuf_qbuf
538			we take current->mm->mmap_lock there, to prevent
539			locking inversion, so don't take it here */
540
541			err = videobuf_dma_init_user_locked(&mem->dma,
542						      DMA_FROM_DEVICE,
543						      vb->baddr, vb->bsize);
544			if (0 != err)
545				return err;
546		}
547		break;
548	case V4L2_MEMORY_OVERLAY:
549		if (NULL == fbuf)
550			return -EINVAL;
551		/* FIXME: need sanity checks for vb->boff */
552		/*
553		 * Using a double cast to avoid compiler warnings when
554		 * building for PAE. Compiler doesn't like direct casting
555		 * of a 32 bit ptr to 64 bit integer.
556		 */
557		bus   = (dma_addr_t)(unsigned long)fbuf->base + vb->boff;
558		pages = PAGE_ALIGN(vb->size) >> PAGE_SHIFT;
559		err = videobuf_dma_init_overlay(&mem->dma, DMA_FROM_DEVICE,
560						bus, pages);
561		if (0 != err)
562			return err;
563		break;
564	default:
565		BUG();
566	}
567	err = videobuf_dma_map(q->dev, &mem->dma);
568	if (0 != err)
569		return err;
570
571	return 0;
572}
573
574static int __videobuf_sync(struct videobuf_queue *q,
575			   struct videobuf_buffer *buf)
576{
577	struct videobuf_dma_sg_memory *mem = buf->priv;
578	BUG_ON(!mem || !mem->dma.sglen);
579
580	MAGIC_CHECK(mem->magic, MAGIC_SG_MEM);
581	MAGIC_CHECK(mem->dma.magic, MAGIC_DMABUF);
582
583	dma_sync_sg_for_cpu(q->dev, mem->dma.sglist,
584			    mem->dma.nr_pages, mem->dma.direction);
585
586	return 0;
587}
588
589static int __videobuf_mmap_mapper(struct videobuf_queue *q,
590				  struct videobuf_buffer *buf,
591				  struct vm_area_struct *vma)
592{
593	struct videobuf_dma_sg_memory *mem = buf->priv;
594	struct videobuf_mapping *map;
595	unsigned int first, last, size = 0, i;
596	int retval;
597
598	retval = -EINVAL;
599
600	BUG_ON(!mem);
601	MAGIC_CHECK(mem->magic, MAGIC_SG_MEM);
602
603	/* look for first buffer to map */
604	for (first = 0; first < VIDEO_MAX_FRAME; first++) {
605		if (buf == q->bufs[first]) {
606			size = PAGE_ALIGN(q->bufs[first]->bsize);
607			break;
608		}
609	}
610
611	/* paranoia, should never happen since buf is always valid. */
612	if (!size) {
613		dprintk(1, "mmap app bug: offset invalid [offset=0x%lx]\n",
614				(vma->vm_pgoff << PAGE_SHIFT));
615		goto done;
616	}
617
618	last = first;
619
620	/* create mapping + update buffer list */
621	retval = -ENOMEM;
622	map = kmalloc(sizeof(struct videobuf_mapping), GFP_KERNEL);
623	if (NULL == map)
624		goto done;
625
626	size = 0;
627	for (i = first; i <= last; i++) {
628		if (NULL == q->bufs[i])
629			continue;
630		q->bufs[i]->map   = map;
631		q->bufs[i]->baddr = vma->vm_start + size;
632		size += PAGE_ALIGN(q->bufs[i]->bsize);
633	}
634
635	map->count    = 1;
636	map->q        = q;
637	vma->vm_ops   = &videobuf_vm_ops;
638	vma->vm_flags |= VM_DONTEXPAND | VM_DONTDUMP;
639	vma->vm_flags &= ~VM_IO; /* using shared anonymous pages */
640	vma->vm_private_data = map;
641	dprintk(1, "mmap %p: q=%p %08lx-%08lx pgoff %08lx bufs %d-%d\n",
642		map, q, vma->vm_start, vma->vm_end, vma->vm_pgoff, first, last);
643	retval = 0;
644
645done:
646	return retval;
647}
648
649static struct videobuf_qtype_ops sg_ops = {
650	.magic        = MAGIC_QTYPE_OPS,
651
652	.alloc_vb     = __videobuf_alloc_vb,
653	.iolock       = __videobuf_iolock,
654	.sync         = __videobuf_sync,
655	.mmap_mapper  = __videobuf_mmap_mapper,
656	.vaddr        = __videobuf_to_vaddr,
657};
658
659void *videobuf_sg_alloc(size_t size)
660{
661	struct videobuf_queue q;
662
663	/* Required to make generic handler to call __videobuf_alloc */
664	q.int_ops = &sg_ops;
665
666	q.msize = size;
667
668	return videobuf_alloc_vb(&q);
669}
670EXPORT_SYMBOL_GPL(videobuf_sg_alloc);
671
672void videobuf_queue_sg_init(struct videobuf_queue *q,
673			 const struct videobuf_queue_ops *ops,
674			 struct device *dev,
675			 spinlock_t *irqlock,
676			 enum v4l2_buf_type type,
677			 enum v4l2_field field,
678			 unsigned int msize,
679			 void *priv,
680			 struct mutex *ext_lock)
681{
682	videobuf_queue_core_init(q, ops, dev, irqlock, type, field, msize,
683				 priv, &sg_ops, ext_lock);
684}
685EXPORT_SYMBOL_GPL(videobuf_queue_sg_init);
686
687