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