1 // SPDX-License-Identifier: GPL-2.0-only
3 * helper functions for SG DMA video4linux capture buffers
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.
10 * (c) 2007 Mauro Carvalho Chehab, <mchehab@kernel.org>
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
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>
26 #include <linux/dma-mapping.h>
27 #include <linux/vmalloc.h>
28 #include <linux/pagemap.h>
29 #include <linux/scatterlist.h>
32 #include <media/videobuf-dma-sg.h>
34 #define MAGIC_DMABUF 0x19721112
35 #define MAGIC_SG_MEM 0x17890714
37 #define MAGIC_CHECK(is, should) \
38 if (unlikely((is) != (should))) { \
39 printk(KERN_ERR "magic mismatch: %x (expected %x)\n", \
45 module_param(debug, int, 0644);
47 MODULE_DESCRIPTION("helper module to manage video4linux dma sg buffers");
48 MODULE_AUTHOR("Mauro Carvalho Chehab <mchehab@kernel.org>");
49 MODULE_LICENSE("GPL");
51 #define dprintk(level, fmt, arg...) \
53 printk(KERN_DEBUG "vbuf-sg: " fmt , ## arg)
55 /* --------------------------------------------------------------------- */
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.
62 static struct scatterlist *videobuf_vmalloc_to_sg(unsigned char *virt,
65 struct scatterlist *sglist;
69 sglist = vzalloc(array_size(nr_pages, sizeof(*sglist)));
72 sg_init_table(sglist, nr_pages);
73 for (i = 0; i < nr_pages; i++, virt += PAGE_SIZE) {
74 pg = vmalloc_to_page(virt);
77 BUG_ON(PageHighMem(pg));
78 sg_set_page(&sglist[i], pg, PAGE_SIZE, 0);
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.
92 static struct scatterlist *videobuf_pages_to_sg(struct page **pages,
93 int nr_pages, int offset, size_t size)
95 struct scatterlist *sglist;
100 sglist = vmalloc(array_size(nr_pages, sizeof(*sglist)));
103 sg_init_table(sglist, nr_pages);
105 if (PageHighMem(pages[0]))
106 /* DMA to highmem pages might not work */
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])
114 if (PageHighMem(pages[i]))
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);
122 dprintk(2, "sgl: oops - no page\n");
127 dprintk(2, "sgl: oops - highmem page\n");
132 /* --------------------------------------------------------------------- */
134 struct videobuf_dmabuf *videobuf_to_dma(struct videobuf_buffer *buf)
136 struct videobuf_dma_sg_memory *mem = buf->priv;
139 MAGIC_CHECK(mem->magic, MAGIC_SG_MEM);
143 EXPORT_SYMBOL_GPL(videobuf_to_dma);
145 static void videobuf_dma_init(struct videobuf_dmabuf *dma)
147 memset(dma, 0, sizeof(*dma));
148 dma->magic = MAGIC_DMABUF;
151 static int videobuf_dma_init_user_locked(struct videobuf_dmabuf *dma,
152 int direction, unsigned long data, unsigned long size)
154 unsigned long first, last;
156 unsigned int flags = FOLL_FORCE;
158 dma->direction = direction;
159 switch (dma->direction) {
160 case DMA_FROM_DEVICE:
170 first = (data & PAGE_MASK) >> PAGE_SHIFT;
171 last = ((data+size-1) & PAGE_MASK) >> PAGE_SHIFT;
172 dma->offset = data & ~PAGE_MASK;
174 dma->nr_pages = last-first+1;
175 dma->pages = kmalloc_array(dma->nr_pages, sizeof(struct page *),
177 if (NULL == dma->pages)
183 dprintk(1, "init user [0x%lx+0x%lx => %lu pages]\n",
184 data, size, dma->nr_pages);
186 err = pin_user_pages(data & PAGE_MASK, dma->nr_pages,
187 flags | FOLL_LONGTERM, dma->pages, NULL);
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,
193 return err < 0 ? err : -EINVAL;
198 static int videobuf_dma_init_user(struct videobuf_dmabuf *dma, int direction,
199 unsigned long data, unsigned long size)
203 mmap_read_lock(current->mm);
204 ret = videobuf_dma_init_user_locked(dma, direction, data, size);
205 mmap_read_unlock(current->mm);
210 static int videobuf_dma_init_kernel(struct videobuf_dmabuf *dma, int direction,
211 unsigned long nr_pages)
215 dprintk(1, "init kernel [%lu pages]\n", nr_pages);
217 dma->direction = direction;
218 dma->vaddr_pages = kcalloc(nr_pages, sizeof(*dma->vaddr_pages),
220 if (!dma->vaddr_pages)
223 dma->dma_addr = kcalloc(nr_pages, sizeof(*dma->dma_addr), GFP_KERNEL);
224 if (!dma->dma_addr) {
225 kfree(dma->vaddr_pages);
228 for (i = 0; i < nr_pages; i++) {
231 addr = dma_alloc_coherent(dma->dev, PAGE_SIZE,
232 &(dma->dma_addr[i]), GFP_KERNEL);
236 dma->vaddr_pages[i] = virt_to_page(addr);
238 dma->vaddr = vmap(dma->vaddr_pages, nr_pages, VM_MAP | VM_IOREMAP,
240 if (NULL == dma->vaddr) {
241 dprintk(1, "vmalloc_32(%lu pages) failed\n", nr_pages);
245 dprintk(1, "vmalloc is at addr %p, size=%lu\n",
246 dma->vaddr, nr_pages << PAGE_SHIFT);
248 memset(dma->vaddr, 0, nr_pages << PAGE_SHIFT);
249 dma->nr_pages = nr_pages;
257 addr = page_address(dma->vaddr_pages[i]);
258 dma_free_coherent(dma->dev, PAGE_SIZE, addr, dma->dma_addr[i]);
260 kfree(dma->dma_addr);
261 dma->dma_addr = NULL;
262 kfree(dma->vaddr_pages);
263 dma->vaddr_pages = NULL;
269 static int videobuf_dma_init_overlay(struct videobuf_dmabuf *dma, int direction,
270 dma_addr_t addr, unsigned long nr_pages)
272 dprintk(1, "init overlay [%lu pages @ bus 0x%lx]\n",
273 nr_pages, (unsigned long)addr);
274 dma->direction = direction;
279 dma->bus_addr = addr;
280 dma->nr_pages = nr_pages;
285 static int videobuf_dma_map(struct device *dev, struct videobuf_dmabuf *dma)
287 MAGIC_CHECK(dma->magic, MAGIC_DMABUF);
288 BUG_ON(0 == dma->nr_pages);
291 dma->sglist = videobuf_pages_to_sg(dma->pages, dma->nr_pages,
292 dma->offset, dma->size);
295 dma->sglist = videobuf_vmalloc_to_sg(dma->vaddr,
299 dma->sglist = vmalloc(sizeof(*dma->sglist));
300 if (NULL != dma->sglist) {
302 sg_dma_address(&dma->sglist[0]) = dma->bus_addr
304 dma->sglist[0].offset = dma->bus_addr & ~PAGE_MASK;
305 sg_dma_len(&dma->sglist[0]) = dma->nr_pages * PAGE_SIZE;
308 if (NULL == dma->sglist) {
309 dprintk(1, "scatterlist is NULL\n");
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) {
317 "%s: videobuf_map_sg failed\n", __func__);
328 int videobuf_dma_unmap(struct device *dev, struct videobuf_dmabuf *dma)
330 MAGIC_CHECK(dma->magic, MAGIC_DMABUF);
335 dma_unmap_sg(dev, dma->sglist, dma->nr_pages, dma->direction);
343 EXPORT_SYMBOL_GPL(videobuf_dma_unmap);
345 int videobuf_dma_free(struct videobuf_dmabuf *dma)
348 MAGIC_CHECK(dma->magic, MAGIC_DMABUF);
352 unpin_user_pages_dirty_lock(dma->pages, dma->nr_pages,
353 dma->direction == DMA_FROM_DEVICE);
359 for (i = 0; i < dma->nr_pages; i++) {
362 addr = page_address(dma->vaddr_pages[i]);
363 dma_free_coherent(dma->dev, PAGE_SIZE, addr,
366 kfree(dma->dma_addr);
367 dma->dma_addr = NULL;
368 kfree(dma->vaddr_pages);
369 dma->vaddr_pages = NULL;
376 dma->direction = DMA_NONE;
380 EXPORT_SYMBOL_GPL(videobuf_dma_free);
382 /* --------------------------------------------------------------------- */
384 static void videobuf_vm_open(struct vm_area_struct *vma)
386 struct videobuf_mapping *map = vma->vm_private_data;
388 dprintk(2, "vm_open %p [count=%d,vma=%08lx-%08lx]\n", map,
389 map->count, vma->vm_start, vma->vm_end);
394 static void videobuf_vm_close(struct vm_area_struct *vma)
396 struct videobuf_mapping *map = vma->vm_private_data;
397 struct videobuf_queue *q = map->q;
398 struct videobuf_dma_sg_memory *mem;
401 dprintk(2, "vm_close %p [count=%d,vma=%08lx-%08lx]\n", map,
402 map->count, vma->vm_start, vma->vm_end);
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])
411 mem = q->bufs[i]->priv;
415 MAGIC_CHECK(mem->magic, MAGIC_SG_MEM);
417 if (q->bufs[i]->map != map)
419 q->bufs[i]->map = NULL;
420 q->bufs[i]->baddr = 0;
421 q->ops->buf_release(q, q->bufs[i]);
423 videobuf_queue_unlock(q);
429 * Get a anonymous page for the mapping. Make sure we can DMA to that
430 * memory location with 32bit PCI devices (i.e. don't use highmem for
431 * now ...). Bounce buffers don't work very well for the data rates
434 static vm_fault_t videobuf_vm_fault(struct vm_fault *vmf)
436 struct vm_area_struct *vma = vmf->vma;
439 dprintk(3, "fault: fault @ %08lx [vma %08lx-%08lx]\n",
440 vmf->address, vma->vm_start, vma->vm_end);
442 page = alloc_page(GFP_USER | __GFP_DMA32);
445 clear_user_highpage(page, vmf->address);
451 static const struct vm_operations_struct videobuf_vm_ops = {
452 .open = videobuf_vm_open,
453 .close = videobuf_vm_close,
454 .fault = videobuf_vm_fault,
457 /* ---------------------------------------------------------------------
458 * SG handlers for the generic methods
461 /* Allocated area consists on 3 parts:
463 struct <driver>_buffer (cx88_buffer, saa7134_buf, ...)
464 struct videobuf_dma_sg_memory
467 static struct videobuf_buffer *__videobuf_alloc_vb(size_t size)
469 struct videobuf_dma_sg_memory *mem;
470 struct videobuf_buffer *vb;
472 vb = kzalloc(size + sizeof(*mem), GFP_KERNEL);
476 mem = vb->priv = ((char *)vb) + size;
477 mem->magic = MAGIC_SG_MEM;
479 videobuf_dma_init(&mem->dma);
481 dprintk(1, "%s: allocated at %p(%ld+%ld) & %p(%ld)\n",
482 __func__, vb, (long)sizeof(*vb), (long)size - sizeof(*vb),
483 mem, (long)sizeof(*mem));
488 static void *__videobuf_to_vaddr(struct videobuf_buffer *buf)
490 struct videobuf_dma_sg_memory *mem = buf->priv;
493 MAGIC_CHECK(mem->magic, MAGIC_SG_MEM);
495 return mem->dma.vaddr;
498 static int __videobuf_iolock(struct videobuf_queue *q,
499 struct videobuf_buffer *vb,
500 struct v4l2_framebuffer *fbuf)
502 struct videobuf_dma_sg_memory *mem = vb->priv;
509 MAGIC_CHECK(mem->magic, MAGIC_SG_MEM);
512 mem->dma.dev = q->dev;
514 WARN_ON(mem->dma.dev != q->dev);
516 switch (vb->memory) {
517 case V4L2_MEMORY_MMAP:
518 case V4L2_MEMORY_USERPTR:
519 if (0 == vb->baddr) {
520 /* no userspace addr -- kernel bounce buffer */
521 pages = PAGE_ALIGN(vb->size) >> PAGE_SHIFT;
522 err = videobuf_dma_init_kernel(&mem->dma,
527 } else if (vb->memory == V4L2_MEMORY_USERPTR) {
528 /* dma directly to userspace */
529 err = videobuf_dma_init_user(&mem->dma,
531 vb->baddr, vb->bsize);
535 /* NOTE: HACK: videobuf_iolock on V4L2_MEMORY_MMAP
536 buffers can only be called from videobuf_qbuf
537 we take current->mm->mmap_lock there, to prevent
538 locking inversion, so don't take it here */
540 err = videobuf_dma_init_user_locked(&mem->dma,
542 vb->baddr, vb->bsize);
547 case V4L2_MEMORY_OVERLAY:
550 /* FIXME: need sanity checks for vb->boff */
552 * Using a double cast to avoid compiler warnings when
553 * building for PAE. Compiler doesn't like direct casting
554 * of a 32 bit ptr to 64 bit integer.
556 bus = (dma_addr_t)(unsigned long)fbuf->base + vb->boff;
557 pages = PAGE_ALIGN(vb->size) >> PAGE_SHIFT;
558 err = videobuf_dma_init_overlay(&mem->dma, DMA_FROM_DEVICE,
566 err = videobuf_dma_map(q->dev, &mem->dma);
573 static int __videobuf_sync(struct videobuf_queue *q,
574 struct videobuf_buffer *buf)
576 struct videobuf_dma_sg_memory *mem = buf->priv;
577 BUG_ON(!mem || !mem->dma.sglen);
579 MAGIC_CHECK(mem->magic, MAGIC_SG_MEM);
580 MAGIC_CHECK(mem->dma.magic, MAGIC_DMABUF);
582 dma_sync_sg_for_cpu(q->dev, mem->dma.sglist,
583 mem->dma.nr_pages, mem->dma.direction);
588 static int __videobuf_mmap_mapper(struct videobuf_queue *q,
589 struct videobuf_buffer *buf,
590 struct vm_area_struct *vma)
592 struct videobuf_dma_sg_memory *mem = buf->priv;
593 struct videobuf_mapping *map;
594 unsigned int first, last, size = 0, i;
600 MAGIC_CHECK(mem->magic, MAGIC_SG_MEM);
602 /* look for first buffer to map */
603 for (first = 0; first < VIDEO_MAX_FRAME; first++) {
604 if (buf == q->bufs[first]) {
605 size = PAGE_ALIGN(q->bufs[first]->bsize);
610 /* paranoia, should never happen since buf is always valid. */
612 dprintk(1, "mmap app bug: offset invalid [offset=0x%lx]\n",
613 (vma->vm_pgoff << PAGE_SHIFT));
619 /* create mapping + update buffer list */
621 map = kmalloc(sizeof(struct videobuf_mapping), GFP_KERNEL);
626 for (i = first; i <= last; i++) {
627 if (NULL == q->bufs[i])
629 q->bufs[i]->map = map;
630 q->bufs[i]->baddr = vma->vm_start + size;
631 size += PAGE_ALIGN(q->bufs[i]->bsize);
636 vma->vm_ops = &videobuf_vm_ops;
637 vma->vm_flags |= VM_DONTEXPAND | VM_DONTDUMP;
638 vma->vm_flags &= ~VM_IO; /* using shared anonymous pages */
639 vma->vm_private_data = map;
640 dprintk(1, "mmap %p: q=%p %08lx-%08lx pgoff %08lx bufs %d-%d\n",
641 map, q, vma->vm_start, vma->vm_end, vma->vm_pgoff, first, last);
648 static struct videobuf_qtype_ops sg_ops = {
649 .magic = MAGIC_QTYPE_OPS,
651 .alloc_vb = __videobuf_alloc_vb,
652 .iolock = __videobuf_iolock,
653 .sync = __videobuf_sync,
654 .mmap_mapper = __videobuf_mmap_mapper,
655 .vaddr = __videobuf_to_vaddr,
658 void *videobuf_sg_alloc(size_t size)
660 struct videobuf_queue q;
662 /* Required to make generic handler to call __videobuf_alloc */
667 return videobuf_alloc_vb(&q);
669 EXPORT_SYMBOL_GPL(videobuf_sg_alloc);
671 void videobuf_queue_sg_init(struct videobuf_queue *q,
672 const struct videobuf_queue_ops *ops,
675 enum v4l2_buf_type type,
676 enum v4l2_field field,
679 struct mutex *ext_lock)
681 videobuf_queue_core_init(q, ops, dev, irqlock, type, field, msize,
682 priv, &sg_ops, ext_lock);
684 EXPORT_SYMBOL_GPL(videobuf_queue_sg_init);