2 * helper functions for SG DMA video4linux capture buffers
4 * The functions expect the hardware being able to scatter gather
5 * (i.e. the buffers are not linear in physical memory, but fragmented
6 * into PAGE_SIZE chunks). They also assume the driver does not need
7 * to touch the video data.
9 * (c) 2007 Mauro Carvalho Chehab, <mchehab@infradead.org>
11 * Highly based on video-buf written originally by:
12 * (c) 2001,02 Gerd Knorr <kraxel@bytesex.org>
13 * (c) 2006 Mauro Carvalho Chehab, <mchehab@infradead.org>
14 * (c) 2006 Ted Walther and John Sokol
16 * This program is free software; you can redistribute it and/or modify
17 * it under the terms of the GNU General Public License as published by
18 * the Free Software Foundation; either version 2
21 #include <linux/init.h>
22 #include <linux/module.h>
23 #include <linux/moduleparam.h>
24 #include <linux/sched.h>
25 #include <linux/slab.h>
26 #include <linux/interrupt.h>
28 #include <linux/dma-mapping.h>
29 #include <linux/vmalloc.h>
30 #include <linux/pagemap.h>
31 #include <linux/scatterlist.h>
33 #include <asm/pgtable.h>
35 #include <media/videobuf-dma-sg.h>
37 #define MAGIC_DMABUF 0x19721112
38 #define MAGIC_SG_MEM 0x17890714
40 #define MAGIC_CHECK(is, should) \
41 if (unlikely((is) != (should))) { \
42 printk(KERN_ERR "magic mismatch: %x (expected %x)\n", \
48 module_param(debug, int, 0644);
50 MODULE_DESCRIPTION("helper module to manage video4linux dma sg buffers");
51 MODULE_AUTHOR("Mauro Carvalho Chehab <mchehab@infradead.org>");
52 MODULE_LICENSE("GPL");
54 #define dprintk(level, fmt, arg...) \
56 printk(KERN_DEBUG "vbuf-sg: " fmt , ## arg)
58 /* --------------------------------------------------------------------- */
61 * Return a scatterlist for some page-aligned vmalloc()'ed memory
62 * block (NULL on errors). Memory for the scatterlist is allocated
63 * using kmalloc. The caller must free the memory.
65 static struct scatterlist *videobuf_vmalloc_to_sg(unsigned char *virt,
68 struct scatterlist *sglist;
72 sglist = vmalloc(nr_pages * sizeof(*sglist));
75 memset(sglist, 0, nr_pages * sizeof(*sglist));
76 sg_init_table(sglist, nr_pages);
77 for (i = 0; i < nr_pages; i++, virt += PAGE_SIZE) {
78 pg = vmalloc_to_page(virt);
81 BUG_ON(PageHighMem(pg));
82 sg_set_page(&sglist[i], pg, PAGE_SIZE, 0);
92 * Return a scatterlist for a an array of userpages (NULL on errors).
93 * Memory for the scatterlist is allocated using kmalloc. The caller
94 * must free the memory.
96 static struct scatterlist *videobuf_pages_to_sg(struct page **pages,
97 int nr_pages, int offset)
99 struct scatterlist *sglist;
102 if (NULL == pages[0])
104 sglist = vmalloc(nr_pages * sizeof(*sglist));
107 sg_init_table(sglist, nr_pages);
109 if (PageHighMem(pages[0]))
110 /* DMA to highmem pages might not work */
112 sg_set_page(&sglist[0], pages[0], PAGE_SIZE - offset, offset);
113 for (i = 1; i < nr_pages; i++) {
114 if (NULL == pages[i])
116 if (PageHighMem(pages[i]))
118 sg_set_page(&sglist[i], pages[i], PAGE_SIZE, 0);
123 dprintk(2, "sgl: oops - no page\n");
128 dprintk(2, "sgl: oops - highmem page\n");
133 /* --------------------------------------------------------------------- */
135 struct videobuf_dmabuf *videobuf_to_dma(struct videobuf_buffer *buf)
137 struct videobuf_dma_sg_memory *mem = buf->priv;
140 MAGIC_CHECK(mem->magic, MAGIC_SG_MEM);
144 EXPORT_SYMBOL_GPL(videobuf_to_dma);
146 void videobuf_dma_init(struct videobuf_dmabuf *dma)
148 memset(dma, 0, sizeof(*dma));
149 dma->magic = MAGIC_DMABUF;
151 EXPORT_SYMBOL_GPL(videobuf_dma_init);
153 static int videobuf_dma_init_user_locked(struct videobuf_dmabuf *dma,
154 int direction, unsigned long data, unsigned long size)
156 unsigned long first, last;
159 dma->direction = direction;
160 switch (dma->direction) {
161 case DMA_FROM_DEVICE:
171 first = (data & PAGE_MASK) >> PAGE_SHIFT;
172 last = ((data+size-1) & PAGE_MASK) >> PAGE_SHIFT;
173 dma->offset = data & ~PAGE_MASK;
174 dma->nr_pages = last-first+1;
175 dma->pages = kmalloc(dma->nr_pages * sizeof(struct page *), GFP_KERNEL);
176 if (NULL == dma->pages)
179 dprintk(1, "init user [0x%lx+0x%lx => %d pages]\n",
180 data, size, dma->nr_pages);
182 err = get_user_pages(current, current->mm,
183 data & PAGE_MASK, dma->nr_pages,
184 rw == READ, 1, /* force */
187 if (err != dma->nr_pages) {
188 dma->nr_pages = (err >= 0) ? err : 0;
189 dprintk(1, "get_user_pages: err=%d [%d]\n", err, dma->nr_pages);
190 return err < 0 ? err : -EINVAL;
195 int videobuf_dma_init_user(struct videobuf_dmabuf *dma, int direction,
196 unsigned long data, unsigned long size)
200 down_read(¤t->mm->mmap_sem);
201 ret = videobuf_dma_init_user_locked(dma, direction, data, size);
202 up_read(¤t->mm->mmap_sem);
206 EXPORT_SYMBOL_GPL(videobuf_dma_init_user);
208 int videobuf_dma_init_kernel(struct videobuf_dmabuf *dma, int direction,
211 dprintk(1, "init kernel [%d pages]\n", nr_pages);
213 dma->direction = direction;
214 dma->vaddr = vmalloc_32(nr_pages << PAGE_SHIFT);
215 if (NULL == dma->vaddr) {
216 dprintk(1, "vmalloc_32(%d pages) failed\n", nr_pages);
220 dprintk(1, "vmalloc is at addr 0x%08lx, size=%d\n",
221 (unsigned long)dma->vaddr,
222 nr_pages << PAGE_SHIFT);
224 memset(dma->vaddr, 0, nr_pages << PAGE_SHIFT);
225 dma->nr_pages = nr_pages;
229 EXPORT_SYMBOL_GPL(videobuf_dma_init_kernel);
231 int videobuf_dma_init_overlay(struct videobuf_dmabuf *dma, int direction,
232 dma_addr_t addr, int nr_pages)
234 dprintk(1, "init overlay [%d pages @ bus 0x%lx]\n",
235 nr_pages, (unsigned long)addr);
236 dma->direction = direction;
241 dma->bus_addr = addr;
242 dma->nr_pages = nr_pages;
246 EXPORT_SYMBOL_GPL(videobuf_dma_init_overlay);
248 int videobuf_dma_map(struct device *dev, struct videobuf_dmabuf *dma)
250 MAGIC_CHECK(dma->magic, MAGIC_DMABUF);
251 BUG_ON(0 == dma->nr_pages);
254 dma->sglist = videobuf_pages_to_sg(dma->pages, dma->nr_pages,
258 dma->sglist = videobuf_vmalloc_to_sg(dma->vaddr,
262 dma->sglist = vmalloc(sizeof(*dma->sglist));
263 if (NULL != dma->sglist) {
265 sg_dma_address(&dma->sglist[0]) = dma->bus_addr
267 dma->sglist[0].offset = dma->bus_addr & ~PAGE_MASK;
268 sg_dma_len(&dma->sglist[0]) = dma->nr_pages * PAGE_SIZE;
271 if (NULL == dma->sglist) {
272 dprintk(1, "scatterlist is NULL\n");
275 if (!dma->bus_addr) {
276 dma->sglen = dma_map_sg(dev, dma->sglist,
277 dma->nr_pages, dma->direction);
278 if (0 == dma->sglen) {
280 "%s: videobuf_map_sg failed\n", __func__);
290 EXPORT_SYMBOL_GPL(videobuf_dma_map);
292 int videobuf_dma_unmap(struct device *dev, struct videobuf_dmabuf *dma)
294 MAGIC_CHECK(dma->magic, MAGIC_DMABUF);
299 dma_unmap_sg(dev, dma->sglist, dma->sglen, dma->direction);
307 EXPORT_SYMBOL_GPL(videobuf_dma_unmap);
309 int videobuf_dma_free(struct videobuf_dmabuf *dma)
312 MAGIC_CHECK(dma->magic, MAGIC_DMABUF);
316 for (i = 0; i < dma->nr_pages; i++)
317 page_cache_release(dma->pages[i]);
327 dma->direction = DMA_NONE;
331 EXPORT_SYMBOL_GPL(videobuf_dma_free);
333 /* --------------------------------------------------------------------- */
335 static void videobuf_vm_open(struct vm_area_struct *vma)
337 struct videobuf_mapping *map = vma->vm_private_data;
339 dprintk(2, "vm_open %p [count=%d,vma=%08lx-%08lx]\n", map,
340 map->count, vma->vm_start, vma->vm_end);
345 static void videobuf_vm_close(struct vm_area_struct *vma)
347 struct videobuf_mapping *map = vma->vm_private_data;
348 struct videobuf_queue *q = map->q;
349 struct videobuf_dma_sg_memory *mem;
352 dprintk(2, "vm_close %p [count=%d,vma=%08lx-%08lx]\n", map,
353 map->count, vma->vm_start, vma->vm_end);
356 if (0 == map->count) {
357 dprintk(1, "munmap %p q=%p\n", map, q);
358 mutex_lock(&q->vb_lock);
359 for (i = 0; i < VIDEO_MAX_FRAME; i++) {
360 if (NULL == q->bufs[i])
362 mem = q->bufs[i]->priv;
366 MAGIC_CHECK(mem->magic, MAGIC_SG_MEM);
368 if (q->bufs[i]->map != map)
370 q->bufs[i]->map = NULL;
371 q->bufs[i]->baddr = 0;
372 q->ops->buf_release(q, q->bufs[i]);
374 mutex_unlock(&q->vb_lock);
381 * Get a anonymous page for the mapping. Make sure we can DMA to that
382 * memory location with 32bit PCI devices (i.e. don't use highmem for
383 * now ...). Bounce buffers don't work very well for the data rates
386 static int videobuf_vm_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
390 dprintk(3, "fault: fault @ %08lx [vma %08lx-%08lx]\n",
391 (unsigned long)vmf->virtual_address,
392 vma->vm_start, vma->vm_end);
394 page = alloc_page(GFP_USER | __GFP_DMA32);
397 clear_user_highpage(page, (unsigned long)vmf->virtual_address);
403 static const struct vm_operations_struct videobuf_vm_ops = {
404 .open = videobuf_vm_open,
405 .close = videobuf_vm_close,
406 .fault = videobuf_vm_fault,
409 /* ---------------------------------------------------------------------
410 * SG handlers for the generic methods
413 /* Allocated area consists on 3 parts:
415 struct <driver>_buffer (cx88_buffer, saa7134_buf, ...)
416 struct videobuf_dma_sg_memory
419 static struct videobuf_buffer *__videobuf_alloc_vb(size_t size)
421 struct videobuf_dma_sg_memory *mem;
422 struct videobuf_buffer *vb;
424 vb = kzalloc(size + sizeof(*mem), GFP_KERNEL);
428 mem = vb->priv = ((char *)vb) + size;
429 mem->magic = MAGIC_SG_MEM;
431 videobuf_dma_init(&mem->dma);
433 dprintk(1, "%s: allocated at %p(%ld+%ld) & %p(%ld)\n",
434 __func__, vb, (long)sizeof(*vb), (long)size - sizeof(*vb),
435 mem, (long)sizeof(*mem));
440 static void *__videobuf_to_vaddr(struct videobuf_buffer *buf)
442 struct videobuf_dma_sg_memory *mem = buf->priv;
445 MAGIC_CHECK(mem->magic, MAGIC_SG_MEM);
447 return mem->dma.vaddr;
450 static int __videobuf_iolock(struct videobuf_queue *q,
451 struct videobuf_buffer *vb,
452 struct v4l2_framebuffer *fbuf)
456 struct videobuf_dma_sg_memory *mem = vb->priv;
459 MAGIC_CHECK(mem->magic, MAGIC_SG_MEM);
461 switch (vb->memory) {
462 case V4L2_MEMORY_MMAP:
463 case V4L2_MEMORY_USERPTR:
464 if (0 == vb->baddr) {
465 /* no userspace addr -- kernel bounce buffer */
466 pages = PAGE_ALIGN(vb->size) >> PAGE_SHIFT;
467 err = videobuf_dma_init_kernel(&mem->dma,
472 } else if (vb->memory == V4L2_MEMORY_USERPTR) {
473 /* dma directly to userspace */
474 err = videobuf_dma_init_user(&mem->dma,
476 vb->baddr, vb->bsize);
480 /* NOTE: HACK: videobuf_iolock on V4L2_MEMORY_MMAP
481 buffers can only be called from videobuf_qbuf
482 we take current->mm->mmap_sem there, to prevent
483 locking inversion, so don't take it here */
485 err = videobuf_dma_init_user_locked(&mem->dma,
487 vb->baddr, vb->bsize);
492 case V4L2_MEMORY_OVERLAY:
495 /* FIXME: need sanity checks for vb->boff */
497 * Using a double cast to avoid compiler warnings when
498 * building for PAE. Compiler doesn't like direct casting
499 * of a 32 bit ptr to 64 bit integer.
501 bus = (dma_addr_t)(unsigned long)fbuf->base + vb->boff;
502 pages = PAGE_ALIGN(vb->size) >> PAGE_SHIFT;
503 err = videobuf_dma_init_overlay(&mem->dma, DMA_FROM_DEVICE,
511 err = videobuf_dma_map(q->dev, &mem->dma);
518 static int __videobuf_sync(struct videobuf_queue *q,
519 struct videobuf_buffer *buf)
521 struct videobuf_dma_sg_memory *mem = buf->priv;
522 BUG_ON(!mem || !mem->dma.sglen);
524 MAGIC_CHECK(mem->magic, MAGIC_SG_MEM);
525 MAGIC_CHECK(mem->dma.magic, MAGIC_DMABUF);
527 dma_sync_sg_for_cpu(q->dev, mem->dma.sglist,
528 mem->dma.sglen, mem->dma.direction);
533 static int __videobuf_mmap_mapper(struct videobuf_queue *q,
534 struct videobuf_buffer *buf,
535 struct vm_area_struct *vma)
537 struct videobuf_dma_sg_memory *mem = buf->priv;
538 struct videobuf_mapping *map;
539 unsigned int first, last, size = 0, i;
544 /* This function maintains backwards compatibility with V4L1 and will
545 * map more than one buffer if the vma length is equal to the combined
546 * size of multiple buffers than it will map them together. See
547 * VIDIOCGMBUF in the v4l spec
549 * TODO: Allow drivers to specify if they support this mode
553 MAGIC_CHECK(mem->magic, MAGIC_SG_MEM);
555 /* look for first buffer to map */
556 for (first = 0; first < VIDEO_MAX_FRAME; first++) {
557 if (buf == q->bufs[first]) {
558 size = PAGE_ALIGN(q->bufs[first]->bsize);
563 /* paranoia, should never happen since buf is always valid. */
565 dprintk(1, "mmap app bug: offset invalid [offset=0x%lx]\n",
566 (vma->vm_pgoff << PAGE_SHIFT));
571 #ifdef CONFIG_VIDEO_V4L1_COMPAT
572 if (size != (vma->vm_end - vma->vm_start)) {
573 /* look for last buffer to map */
574 for (last = first + 1; last < VIDEO_MAX_FRAME; last++) {
575 if (NULL == q->bufs[last])
577 if (V4L2_MEMORY_MMAP != q->bufs[last]->memory)
579 if (q->bufs[last]->map) {
583 size += PAGE_ALIGN(q->bufs[last]->bsize);
584 if (size == (vma->vm_end - vma->vm_start))
587 if (VIDEO_MAX_FRAME == last) {
588 dprintk(1, "mmap app bug: size invalid [size=0x%lx]\n",
589 (vma->vm_end - vma->vm_start));
595 /* create mapping + update buffer list */
597 map = kmalloc(sizeof(struct videobuf_mapping), GFP_KERNEL);
602 for (i = first; i <= last; i++) {
603 if (NULL == q->bufs[i])
605 q->bufs[i]->map = map;
606 q->bufs[i]->baddr = vma->vm_start + size;
607 size += PAGE_ALIGN(q->bufs[i]->bsize);
612 vma->vm_ops = &videobuf_vm_ops;
613 vma->vm_flags |= VM_DONTEXPAND | VM_RESERVED;
614 vma->vm_flags &= ~VM_IO; /* using shared anonymous pages */
615 vma->vm_private_data = map;
616 dprintk(1, "mmap %p: q=%p %08lx-%08lx pgoff %08lx bufs %d-%d\n",
617 map, q, vma->vm_start, vma->vm_end, vma->vm_pgoff, first, last);
624 static struct videobuf_qtype_ops sg_ops = {
625 .magic = MAGIC_QTYPE_OPS,
627 .alloc_vb = __videobuf_alloc_vb,
628 .iolock = __videobuf_iolock,
629 .sync = __videobuf_sync,
630 .mmap_mapper = __videobuf_mmap_mapper,
631 .vaddr = __videobuf_to_vaddr,
634 void *videobuf_sg_alloc(size_t size)
636 struct videobuf_queue q;
638 /* Required to make generic handler to call __videobuf_alloc */
643 return videobuf_alloc_vb(&q);
645 EXPORT_SYMBOL_GPL(videobuf_sg_alloc);
647 void videobuf_queue_sg_init(struct videobuf_queue *q,
648 const struct videobuf_queue_ops *ops,
651 enum v4l2_buf_type type,
652 enum v4l2_field field,
656 videobuf_queue_core_init(q, ops, dev, irqlock, type, field, msize,
659 EXPORT_SYMBOL_GPL(videobuf_queue_sg_init);