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 = vzalloc(nr_pages * sizeof(*sglist));
75 sg_init_table(sglist, nr_pages);
76 for (i = 0; i < nr_pages; i++, virt += PAGE_SIZE) {
77 pg = vmalloc_to_page(virt);
80 BUG_ON(PageHighMem(pg));
81 sg_set_page(&sglist[i], pg, PAGE_SIZE, 0);
91 * Return a scatterlist for a an array of userpages (NULL on errors).
92 * Memory for the scatterlist is allocated using kmalloc. The caller
93 * must free the memory.
95 static struct scatterlist *videobuf_pages_to_sg(struct page **pages,
96 int nr_pages, int offset, size_t size)
98 struct scatterlist *sglist;
101 if (NULL == pages[0])
103 sglist = vmalloc(nr_pages * sizeof(*sglist));
106 sg_init_table(sglist, nr_pages);
108 if (PageHighMem(pages[0]))
109 /* DMA to highmem pages might not work */
111 sg_set_page(&sglist[0], pages[0],
112 min_t(size_t, PAGE_SIZE - offset, size), offset);
113 size -= min_t(size_t, PAGE_SIZE - offset, size);
114 for (i = 1; i < nr_pages; i++) {
115 if (NULL == pages[i])
117 if (PageHighMem(pages[i]))
119 sg_set_page(&sglist[i], pages[i], min_t(size_t, PAGE_SIZE, size), 0);
120 size -= min_t(size_t, PAGE_SIZE, size);
125 dprintk(2, "sgl: oops - no page\n");
130 dprintk(2, "sgl: oops - highmem page\n");
135 /* --------------------------------------------------------------------- */
137 struct videobuf_dmabuf *videobuf_to_dma(struct videobuf_buffer *buf)
139 struct videobuf_dma_sg_memory *mem = buf->priv;
142 MAGIC_CHECK(mem->magic, MAGIC_SG_MEM);
146 EXPORT_SYMBOL_GPL(videobuf_to_dma);
148 void videobuf_dma_init(struct videobuf_dmabuf *dma)
150 memset(dma, 0, sizeof(*dma));
151 dma->magic = MAGIC_DMABUF;
153 EXPORT_SYMBOL_GPL(videobuf_dma_init);
155 static int videobuf_dma_init_user_locked(struct videobuf_dmabuf *dma,
156 int direction, unsigned long data, unsigned long size)
158 unsigned long first, last;
161 dma->direction = direction;
162 switch (dma->direction) {
163 case DMA_FROM_DEVICE:
173 first = (data & PAGE_MASK) >> PAGE_SHIFT;
174 last = ((data+size-1) & PAGE_MASK) >> PAGE_SHIFT;
175 dma->offset = data & ~PAGE_MASK;
177 dma->nr_pages = last-first+1;
178 dma->pages = kmalloc(dma->nr_pages * sizeof(struct page *), GFP_KERNEL);
179 if (NULL == dma->pages)
182 dprintk(1, "init user [0x%lx+0x%lx => %d pages]\n",
183 data, size, dma->nr_pages);
185 err = get_user_pages(current, current->mm,
186 data & PAGE_MASK, dma->nr_pages,
187 rw == READ, 1, /* force */
190 if (err != dma->nr_pages) {
191 dma->nr_pages = (err >= 0) ? err : 0;
192 dprintk(1, "get_user_pages: err=%d [%d]\n", err, dma->nr_pages);
193 return err < 0 ? err : -EINVAL;
198 int videobuf_dma_init_user(struct videobuf_dmabuf *dma, int direction,
199 unsigned long data, unsigned long size)
203 down_read(¤t->mm->mmap_sem);
204 ret = videobuf_dma_init_user_locked(dma, direction, data, size);
205 up_read(¤t->mm->mmap_sem);
209 EXPORT_SYMBOL_GPL(videobuf_dma_init_user);
211 int videobuf_dma_init_kernel(struct videobuf_dmabuf *dma, int direction,
214 dprintk(1, "init kernel [%d pages]\n", nr_pages);
216 dma->direction = direction;
217 dma->vaddr = vmalloc_32(nr_pages << PAGE_SHIFT);
218 if (NULL == dma->vaddr) {
219 dprintk(1, "vmalloc_32(%d pages) failed\n", nr_pages);
223 dprintk(1, "vmalloc is at addr 0x%08lx, size=%d\n",
224 (unsigned long)dma->vaddr,
225 nr_pages << PAGE_SHIFT);
227 memset(dma->vaddr, 0, nr_pages << PAGE_SHIFT);
228 dma->nr_pages = nr_pages;
232 EXPORT_SYMBOL_GPL(videobuf_dma_init_kernel);
234 int videobuf_dma_init_overlay(struct videobuf_dmabuf *dma, int direction,
235 dma_addr_t addr, int nr_pages)
237 dprintk(1, "init overlay [%d pages @ bus 0x%lx]\n",
238 nr_pages, (unsigned long)addr);
239 dma->direction = direction;
244 dma->bus_addr = addr;
245 dma->nr_pages = nr_pages;
249 EXPORT_SYMBOL_GPL(videobuf_dma_init_overlay);
251 int videobuf_dma_map(struct device *dev, struct videobuf_dmabuf *dma)
253 MAGIC_CHECK(dma->magic, MAGIC_DMABUF);
254 BUG_ON(0 == dma->nr_pages);
257 dma->sglist = videobuf_pages_to_sg(dma->pages, dma->nr_pages,
258 dma->offset, dma->size);
261 dma->sglist = videobuf_vmalloc_to_sg(dma->vaddr,
265 dma->sglist = vmalloc(sizeof(*dma->sglist));
266 if (NULL != dma->sglist) {
268 sg_dma_address(&dma->sglist[0]) = dma->bus_addr
270 dma->sglist[0].offset = dma->bus_addr & ~PAGE_MASK;
271 sg_dma_len(&dma->sglist[0]) = dma->nr_pages * PAGE_SIZE;
274 if (NULL == dma->sglist) {
275 dprintk(1, "scatterlist is NULL\n");
278 if (!dma->bus_addr) {
279 dma->sglen = dma_map_sg(dev, dma->sglist,
280 dma->nr_pages, dma->direction);
281 if (0 == dma->sglen) {
283 "%s: videobuf_map_sg failed\n", __func__);
293 EXPORT_SYMBOL_GPL(videobuf_dma_map);
295 int videobuf_dma_unmap(struct device *dev, struct videobuf_dmabuf *dma)
297 MAGIC_CHECK(dma->magic, MAGIC_DMABUF);
302 dma_unmap_sg(dev, dma->sglist, dma->sglen, dma->direction);
310 EXPORT_SYMBOL_GPL(videobuf_dma_unmap);
312 int videobuf_dma_free(struct videobuf_dmabuf *dma)
315 MAGIC_CHECK(dma->magic, MAGIC_DMABUF);
319 for (i = 0; i < dma->nr_pages; i++)
320 page_cache_release(dma->pages[i]);
330 dma->direction = DMA_NONE;
334 EXPORT_SYMBOL_GPL(videobuf_dma_free);
336 /* --------------------------------------------------------------------- */
338 static void videobuf_vm_open(struct vm_area_struct *vma)
340 struct videobuf_mapping *map = vma->vm_private_data;
341 struct videobuf_queue *q = map->q;
343 dprintk(2, "vm_open %p [count=%d,vma=%08lx-%08lx]\n", map,
344 map->count, vma->vm_start, vma->vm_end);
346 videobuf_queue_lock(q);
348 videobuf_queue_unlock(q);
351 static void videobuf_vm_close(struct vm_area_struct *vma)
353 struct videobuf_mapping *map = vma->vm_private_data;
354 struct videobuf_queue *q = map->q;
355 struct videobuf_dma_sg_memory *mem;
358 dprintk(2, "vm_close %p [count=%d,vma=%08lx-%08lx]\n", map,
359 map->count, vma->vm_start, vma->vm_end);
361 videobuf_queue_lock(q);
363 dprintk(1, "munmap %p q=%p\n", map, q);
364 for (i = 0; i < VIDEO_MAX_FRAME; i++) {
365 if (NULL == q->bufs[i])
367 mem = q->bufs[i]->priv;
371 MAGIC_CHECK(mem->magic, MAGIC_SG_MEM);
373 if (q->bufs[i]->map != map)
375 q->bufs[i]->map = NULL;
376 q->bufs[i]->baddr = 0;
377 q->ops->buf_release(q, q->bufs[i]);
381 videobuf_queue_unlock(q);
386 * Get a anonymous page for the mapping. Make sure we can DMA to that
387 * memory location with 32bit PCI devices (i.e. don't use highmem for
388 * now ...). Bounce buffers don't work very well for the data rates
391 static int videobuf_vm_fault(struct vm_area_struct *vma, struct vm_fault *vmf)
395 dprintk(3, "fault: fault @ %08lx [vma %08lx-%08lx]\n",
396 (unsigned long)vmf->virtual_address,
397 vma->vm_start, vma->vm_end);
399 page = alloc_page(GFP_USER | __GFP_DMA32);
402 clear_user_highpage(page, (unsigned long)vmf->virtual_address);
408 static const struct vm_operations_struct videobuf_vm_ops = {
409 .open = videobuf_vm_open,
410 .close = videobuf_vm_close,
411 .fault = videobuf_vm_fault,
414 /* ---------------------------------------------------------------------
415 * SG handlers for the generic methods
418 /* Allocated area consists on 3 parts:
420 struct <driver>_buffer (cx88_buffer, saa7134_buf, ...)
421 struct videobuf_dma_sg_memory
424 static struct videobuf_buffer *__videobuf_alloc_vb(size_t size)
426 struct videobuf_dma_sg_memory *mem;
427 struct videobuf_buffer *vb;
429 vb = kzalloc(size + sizeof(*mem), GFP_KERNEL);
433 mem = vb->priv = ((char *)vb) + size;
434 mem->magic = MAGIC_SG_MEM;
436 videobuf_dma_init(&mem->dma);
438 dprintk(1, "%s: allocated at %p(%ld+%ld) & %p(%ld)\n",
439 __func__, vb, (long)sizeof(*vb), (long)size - sizeof(*vb),
440 mem, (long)sizeof(*mem));
445 static void *__videobuf_to_vaddr(struct videobuf_buffer *buf)
447 struct videobuf_dma_sg_memory *mem = buf->priv;
450 MAGIC_CHECK(mem->magic, MAGIC_SG_MEM);
452 return mem->dma.vaddr;
455 static int __videobuf_iolock(struct videobuf_queue *q,
456 struct videobuf_buffer *vb,
457 struct v4l2_framebuffer *fbuf)
461 struct videobuf_dma_sg_memory *mem = vb->priv;
464 MAGIC_CHECK(mem->magic, MAGIC_SG_MEM);
466 switch (vb->memory) {
467 case V4L2_MEMORY_MMAP:
468 case V4L2_MEMORY_USERPTR:
469 if (0 == vb->baddr) {
470 /* no userspace addr -- kernel bounce buffer */
471 pages = PAGE_ALIGN(vb->size) >> PAGE_SHIFT;
472 err = videobuf_dma_init_kernel(&mem->dma,
477 } else if (vb->memory == V4L2_MEMORY_USERPTR) {
478 /* dma directly to userspace */
479 err = videobuf_dma_init_user(&mem->dma,
481 vb->baddr, vb->bsize);
485 /* NOTE: HACK: videobuf_iolock on V4L2_MEMORY_MMAP
486 buffers can only be called from videobuf_qbuf
487 we take current->mm->mmap_sem there, to prevent
488 locking inversion, so don't take it here */
490 err = videobuf_dma_init_user_locked(&mem->dma,
492 vb->baddr, vb->bsize);
497 case V4L2_MEMORY_OVERLAY:
500 /* FIXME: need sanity checks for vb->boff */
502 * Using a double cast to avoid compiler warnings when
503 * building for PAE. Compiler doesn't like direct casting
504 * of a 32 bit ptr to 64 bit integer.
506 bus = (dma_addr_t)(unsigned long)fbuf->base + vb->boff;
507 pages = PAGE_ALIGN(vb->size) >> PAGE_SHIFT;
508 err = videobuf_dma_init_overlay(&mem->dma, DMA_FROM_DEVICE,
516 err = videobuf_dma_map(q->dev, &mem->dma);
523 static int __videobuf_sync(struct videobuf_queue *q,
524 struct videobuf_buffer *buf)
526 struct videobuf_dma_sg_memory *mem = buf->priv;
527 BUG_ON(!mem || !mem->dma.sglen);
529 MAGIC_CHECK(mem->magic, MAGIC_SG_MEM);
530 MAGIC_CHECK(mem->dma.magic, MAGIC_DMABUF);
532 dma_sync_sg_for_cpu(q->dev, mem->dma.sglist,
533 mem->dma.sglen, mem->dma.direction);
538 static int __videobuf_mmap_mapper(struct videobuf_queue *q,
539 struct videobuf_buffer *buf,
540 struct vm_area_struct *vma)
542 struct videobuf_dma_sg_memory *mem = buf->priv;
543 struct videobuf_mapping *map;
544 unsigned int first, last, size = 0, i;
550 MAGIC_CHECK(mem->magic, MAGIC_SG_MEM);
552 /* look for first buffer to map */
553 for (first = 0; first < VIDEO_MAX_FRAME; first++) {
554 if (buf == q->bufs[first]) {
555 size = PAGE_ALIGN(q->bufs[first]->bsize);
560 /* paranoia, should never happen since buf is always valid. */
562 dprintk(1, "mmap app bug: offset invalid [offset=0x%lx]\n",
563 (vma->vm_pgoff << PAGE_SHIFT));
569 /* create mapping + update buffer list */
571 map = kmalloc(sizeof(struct videobuf_mapping), GFP_KERNEL);
576 for (i = first; i <= last; i++) {
577 if (NULL == q->bufs[i])
579 q->bufs[i]->map = map;
580 q->bufs[i]->baddr = vma->vm_start + size;
581 size += PAGE_ALIGN(q->bufs[i]->bsize);
586 vma->vm_ops = &videobuf_vm_ops;
587 vma->vm_flags |= VM_DONTEXPAND | VM_DONTDUMP;
588 vma->vm_flags &= ~VM_IO; /* using shared anonymous pages */
589 vma->vm_private_data = map;
590 dprintk(1, "mmap %p: q=%p %08lx-%08lx pgoff %08lx bufs %d-%d\n",
591 map, q, vma->vm_start, vma->vm_end, vma->vm_pgoff, first, last);
598 static struct videobuf_qtype_ops sg_ops = {
599 .magic = MAGIC_QTYPE_OPS,
601 .alloc_vb = __videobuf_alloc_vb,
602 .iolock = __videobuf_iolock,
603 .sync = __videobuf_sync,
604 .mmap_mapper = __videobuf_mmap_mapper,
605 .vaddr = __videobuf_to_vaddr,
608 void *videobuf_sg_alloc(size_t size)
610 struct videobuf_queue q;
612 /* Required to make generic handler to call __videobuf_alloc */
617 return videobuf_alloc_vb(&q);
619 EXPORT_SYMBOL_GPL(videobuf_sg_alloc);
621 void videobuf_queue_sg_init(struct videobuf_queue *q,
622 const struct videobuf_queue_ops *ops,
625 enum v4l2_buf_type type,
626 enum v4l2_field field,
629 struct mutex *ext_lock)
631 videobuf_queue_core_init(q, ops, dev, irqlock, type, field, msize,
632 priv, &sg_ops, ext_lock);
634 EXPORT_SYMBOL_GPL(videobuf_queue_sg_init);