1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * Copyright (C) 2018-2020 Christoph Hellwig.
4 *
5 * DMA operations that map physical memory directly without using an IOMMU.
6 */
7 #include <linux/memblock.h> /* for max_pfn */
8 #include <linux/export.h>
9 #include <linux/mm.h>
10 #include <linux/dma-map-ops.h>
11 #include <linux/scatterlist.h>
12 #include <linux/pfn.h>
13 #include <linux/vmalloc.h>
14 #include <linux/set_memory.h>
15 #include <linux/slab.h>
16 #include "direct.h"
17
18 /*
19 * Most architectures use ZONE_DMA for the first 16 Megabytes, but some use
20 * it for entirely different regions. In that case the arch code needs to
21 * override the variable below for dma-direct to work properly.
22 */
23 unsigned int zone_dma_bits __ro_after_init = 24;
24
25 static inline dma_addr_t phys_to_dma_direct(struct device *dev,
26 phys_addr_t phys)
27 {
28 if (force_dma_unencrypted(dev))
29 return phys_to_dma_unencrypted(dev, phys);
30 return phys_to_dma(dev, phys);
31 }
32
33 static inline struct page *dma_direct_to_page(struct device *dev,
34 dma_addr_t dma_addr)
35 {
36 return pfn_to_page(PHYS_PFN(dma_to_phys(dev, dma_addr)));
37 }
38
39 u64 dma_direct_get_required_mask(struct device *dev)
40 {
41 phys_addr_t phys = (phys_addr_t)(max_pfn - 1) << PAGE_SHIFT;
42 u64 max_dma = phys_to_dma_direct(dev, phys);
43
44 return (1ULL << (fls64(max_dma) - 1)) * 2 - 1;
45 }
46
47 static gfp_t dma_direct_optimal_gfp_mask(struct device *dev, u64 *phys_limit)
48 {
49 u64 dma_limit = min_not_zero(
50 dev->coherent_dma_mask,
51 dev->bus_dma_limit);
52
53 /*
54 * Optimistically try the zone that the physical address mask falls
55 * into first. If that returns memory that isn't actually addressable
56 * we will fallback to the next lower zone and try again.
57 *
58 * Note that GFP_DMA32 and GFP_DMA are no ops without the corresponding
59 * zones.
60 */
61 *phys_limit = dma_to_phys(dev, dma_limit);
62 if (*phys_limit <= DMA_BIT_MASK(zone_dma_bits))
63 return GFP_DMA;
64 if (*phys_limit <= DMA_BIT_MASK(32))
65 return GFP_DMA32;
66 return 0;
67 }
68
69 bool dma_coherent_ok(struct device *dev, phys_addr_t phys, size_t size)
70 {
71 dma_addr_t dma_addr = phys_to_dma_direct(dev, phys);
72
73 if (dma_addr == DMA_MAPPING_ERROR)
74 return false;
75 return dma_addr + size - 1 <=
76 min_not_zero(dev->coherent_dma_mask, dev->bus_dma_limit);
77 }
78
79 static int dma_set_decrypted(struct device *dev, void *vaddr, size_t size)
80 {
81 if (!force_dma_unencrypted(dev))
82 return 0;
83 return set_memory_decrypted((unsigned long)vaddr, PFN_UP(size));
84 }
85
86 static int dma_set_encrypted(struct device *dev, void *vaddr, size_t size)
87 {
88 int ret;
89
90 if (!force_dma_unencrypted(dev))
91 return 0;
92 ret = set_memory_encrypted((unsigned long)vaddr, PFN_UP(size));
93 if (ret)
94 pr_warn_ratelimited("leaking DMA memory that can't be re-encrypted\n");
95 return ret;
96 }
97
98 static void __dma_direct_free_pages(struct device *dev, struct page *page,
99 size_t size)
100 {
101 if (swiotlb_free(dev, page, size))
102 return;
103 dma_free_contiguous(dev, page, size);
104 }
105
106 static struct page *dma_direct_alloc_swiotlb(struct device *dev, size_t size)
107 {
108 struct page *page = swiotlb_alloc(dev, size);
109
110 if (page && !dma_coherent_ok(dev, page_to_phys(page), size)) {
111 swiotlb_free(dev, page, size);
112 return NULL;
113 }
114
115 return page;
116 }
117
118 static struct page *__dma_direct_alloc_pages(struct device *dev, size_t size,
119 gfp_t gfp, bool allow_highmem)
120 {
121 int node = dev_to_node(dev);
122 struct page *page = NULL;
123 u64 phys_limit;
124
125 WARN_ON_ONCE(!PAGE_ALIGNED(size));
126
127 if (is_swiotlb_for_alloc(dev))
128 return dma_direct_alloc_swiotlb(dev, size);
129
130 gfp |= dma_direct_optimal_gfp_mask(dev, &phys_limit);
131 page = dma_alloc_contiguous(dev, size, gfp);
132 if (page) {
133 if (!dma_coherent_ok(dev, page_to_phys(page), size) ||
134 (!allow_highmem && PageHighMem(page))) {
135 dma_free_contiguous(dev, page, size);
136 page = NULL;
137 }
138 }
139 again:
140 if (!page)
141 page = alloc_pages_node(node, gfp, get_order(size));
142 if (page && !dma_coherent_ok(dev, page_to_phys(page), size)) {
143 dma_free_contiguous(dev, page, size);
144 page = NULL;
145
146 if (IS_ENABLED(CONFIG_ZONE_DMA32) &&
147 phys_limit < DMA_BIT_MASK(64) &&
148 !(gfp & (GFP_DMA32 | GFP_DMA))) {
149 gfp |= GFP_DMA32;
150 goto again;
151 }
152
153 if (IS_ENABLED(CONFIG_ZONE_DMA) && !(gfp & GFP_DMA)) {
154 gfp = (gfp & ~GFP_DMA32) | GFP_DMA;
155 goto again;
156 }
157 }
158
159 return page;
160 }
161
162 /*
163 * Check if a potentially blocking operations needs to dip into the atomic
164 * pools for the given device/gfp.
165 */
166 static bool dma_direct_use_pool(struct device *dev, gfp_t gfp)
167 {
168 return !gfpflags_allow_blocking(gfp) && !is_swiotlb_for_alloc(dev);
169 }
170
171 static void *dma_direct_alloc_from_pool(struct device *dev, size_t size,
172 dma_addr_t *dma_handle, gfp_t gfp)
173 {
174 struct page *page;
175 u64 phys_limit;
176 void *ret;
177
178 if (WARN_ON_ONCE(!IS_ENABLED(CONFIG_DMA_COHERENT_POOL)))
179 return NULL;
180
181 gfp |= dma_direct_optimal_gfp_mask(dev, &phys_limit);
182 page = dma_alloc_from_pool(dev, size, &ret, gfp, dma_coherent_ok);
183 if (!page)
184 return NULL;
185 *dma_handle = phys_to_dma_direct(dev, page_to_phys(page));
186 return ret;
187 }
188
189 static void *dma_direct_alloc_no_mapping(struct device *dev, size_t size,
190 dma_addr_t *dma_handle, gfp_t gfp)
191 {
192 struct page *page;
193
194 page = __dma_direct_alloc_pages(dev, size, gfp & ~__GFP_ZERO, true);
195 if (!page)
196 return NULL;
197
198 /* remove any dirty cache lines on the kernel alias */
199 if (!PageHighMem(page))
200 arch_dma_prep_coherent(page, size);
201
202 /* return the page pointer as the opaque cookie */
203 *dma_handle = phys_to_dma_direct(dev, page_to_phys(page));
204 return page;
205 }
206
207 void *dma_direct_alloc(struct device *dev, size_t size,
208 dma_addr_t *dma_handle, gfp_t gfp, unsigned long attrs)
209 {
210 bool remap = false, set_uncached = false;
211 struct page *page;
212 void *ret;
213
214 size = PAGE_ALIGN(size);
215 if (attrs & DMA_ATTR_NO_WARN)
216 gfp |= __GFP_NOWARN;
217
218 if ((attrs & DMA_ATTR_NO_KERNEL_MAPPING) &&
219 !force_dma_unencrypted(dev) && !is_swiotlb_for_alloc(dev))
220 return dma_direct_alloc_no_mapping(dev, size, dma_handle, gfp);
221
222 if (!dev_is_dma_coherent(dev)) {
223 if (IS_ENABLED(CONFIG_ARCH_HAS_DMA_ALLOC) &&
224 !is_swiotlb_for_alloc(dev))
225 return arch_dma_alloc(dev, size, dma_handle, gfp,
226 attrs);
227
228 /*
229 * If there is a global pool, always allocate from it for
230 * non-coherent devices.
231 */
232 if (IS_ENABLED(CONFIG_DMA_GLOBAL_POOL))
233 return dma_alloc_from_global_coherent(dev, size,
234 dma_handle);
235
236 /*
237 * Otherwise we require the architecture to either be able to
238 * mark arbitrary parts of the kernel direct mapping uncached,
239 * or remapped it uncached.
240 */
241 set_uncached = IS_ENABLED(CONFIG_ARCH_HAS_DMA_SET_UNCACHED);
242 remap = IS_ENABLED(CONFIG_DMA_DIRECT_REMAP);
243 if (!set_uncached && !remap) {
244 pr_warn_once("coherent DMA allocations not supported on this platform.\n");
245 return NULL;
246 }
247 }
248
249 /*
250 * Remapping or decrypting memory may block, allocate the memory from
251 * the atomic pools instead if we aren't allowed block.
252 */
253 if ((remap || force_dma_unencrypted(dev)) &&
254 dma_direct_use_pool(dev, gfp))
255 return dma_direct_alloc_from_pool(dev, size, dma_handle, gfp);
256
257 /* we always manually zero the memory once we are done */
258 page = __dma_direct_alloc_pages(dev, size, gfp & ~__GFP_ZERO, true);
259 if (!page)
260 return NULL;
261
262 /*
263 * dma_alloc_contiguous can return highmem pages depending on a
264 * combination the cma= arguments and per-arch setup. These need to be
265 * remapped to return a kernel virtual address.
266 */
267 if (PageHighMem(page)) {
268 remap = true;
269 set_uncached = false;
270 }
271
272 if (remap) {
273 pgprot_t prot = dma_pgprot(dev, PAGE_KERNEL, attrs);
274
275 if (force_dma_unencrypted(dev))
276 prot = pgprot_decrypted(prot);
277
278 /* remove any dirty cache lines on the kernel alias */
279 arch_dma_prep_coherent(page, size);
280
281 /* create a coherent mapping */
282 ret = dma_common_contiguous_remap(page, size, prot,
283 __builtin_return_address(0));
284 if (!ret)
285 goto out_free_pages;
286 } else {
287 ret = page_address(page);
288 if (dma_set_decrypted(dev, ret, size))
289 goto out_leak_pages;
290 }
291
292 memset(ret, 0, size);
293
294 if (set_uncached) {
295 arch_dma_prep_coherent(page, size);
296 ret = arch_dma_set_uncached(ret, size);
297 if (IS_ERR(ret))
298 goto out_encrypt_pages;
299 }
300
301 *dma_handle = phys_to_dma_direct(dev, page_to_phys(page));
302 return ret;
303
304 out_encrypt_pages:
305 if (dma_set_encrypted(dev, page_address(page), size))
306 return NULL;
307 out_free_pages:
308 __dma_direct_free_pages(dev, page, size);
309 return NULL;
310 out_leak_pages:
311 return NULL;
312 }
313
314 void dma_direct_free(struct device *dev, size_t size,
315 void *cpu_addr, dma_addr_t dma_addr, unsigned long attrs)
316 {
317 unsigned int page_order = get_order(size);
318
319 if ((attrs & DMA_ATTR_NO_KERNEL_MAPPING) &&
320 !force_dma_unencrypted(dev) && !is_swiotlb_for_alloc(dev)) {
321 /* cpu_addr is a struct page cookie, not a kernel address */
322 dma_free_contiguous(dev, cpu_addr, size);
323 return;
324 }
325
326 if (IS_ENABLED(CONFIG_ARCH_HAS_DMA_ALLOC) &&
327 !dev_is_dma_coherent(dev) &&
328 !is_swiotlb_for_alloc(dev)) {
329 arch_dma_free(dev, size, cpu_addr, dma_addr, attrs);
330 return;
331 }
332
333 if (IS_ENABLED(CONFIG_DMA_GLOBAL_POOL) &&
334 !dev_is_dma_coherent(dev)) {
335 if (!dma_release_from_global_coherent(page_order, cpu_addr))
336 WARN_ON_ONCE(1);
337 return;
338 }
339
340 /* If cpu_addr is not from an atomic pool, dma_free_from_pool() fails */
341 if (IS_ENABLED(CONFIG_DMA_COHERENT_POOL) &&
342 dma_free_from_pool(dev, cpu_addr, PAGE_ALIGN(size)))
343 return;
344
345 if (is_vmalloc_addr(cpu_addr)) {
346 vunmap(cpu_addr);
347 } else {
348 if (IS_ENABLED(CONFIG_ARCH_HAS_DMA_CLEAR_UNCACHED))
349 arch_dma_clear_uncached(cpu_addr, size);
350 if (dma_set_encrypted(dev, cpu_addr, size))
351 return;
352 }
353
354 __dma_direct_free_pages(dev, dma_direct_to_page(dev, dma_addr), size);
355 }
356
357 struct page *dma_direct_alloc_pages(struct device *dev, size_t size,
358 dma_addr_t *dma_handle, enum dma_data_direction dir, gfp_t gfp)
359 {
360 struct page *page;
361 void *ret;
362
363 if (force_dma_unencrypted(dev) && dma_direct_use_pool(dev, gfp))
364 return dma_direct_alloc_from_pool(dev, size, dma_handle, gfp);
365
366 page = __dma_direct_alloc_pages(dev, size, gfp, false);
367 if (!page)
368 return NULL;
369
370 ret = page_address(page);
371 if (dma_set_decrypted(dev, ret, size))
372 goto out_leak_pages;
373 memset(ret, 0, size);
374 *dma_handle = phys_to_dma_direct(dev, page_to_phys(page));
375 return page;
376 out_leak_pages:
377 return NULL;
378 }
379
380 void dma_direct_free_pages(struct device *dev, size_t size,
381 struct page *page, dma_addr_t dma_addr,
382 enum dma_data_direction dir)
383 {
384 void *vaddr = page_address(page);
385
386 /* If cpu_addr is not from an atomic pool, dma_free_from_pool() fails */
387 if (IS_ENABLED(CONFIG_DMA_COHERENT_POOL) &&
388 dma_free_from_pool(dev, vaddr, size))
389 return;
390
391 if (dma_set_encrypted(dev, vaddr, size))
392 return;
393 __dma_direct_free_pages(dev, page, size);
394 }
395
396 #if defined(CONFIG_ARCH_HAS_SYNC_DMA_FOR_DEVICE) || \
397 defined(CONFIG_SWIOTLB)
398 void dma_direct_sync_sg_for_device(struct device *dev,
399 struct scatterlist *sgl, int nents, enum dma_data_direction dir)
400 {
401 struct scatterlist *sg;
402 int i;
403
404 for_each_sg(sgl, sg, nents, i) {
405 phys_addr_t paddr = dma_to_phys(dev, sg_dma_address(sg));
406
407 swiotlb_sync_single_for_device(dev, paddr, sg->length, dir);
408
409 if (!dev_is_dma_coherent(dev))
410 arch_sync_dma_for_device(paddr, sg->length,
411 dir);
412 }
413 }
414 #endif
415
416 #if defined(CONFIG_ARCH_HAS_SYNC_DMA_FOR_CPU) || \
417 defined(CONFIG_ARCH_HAS_SYNC_DMA_FOR_CPU_ALL) || \
418 defined(CONFIG_SWIOTLB)
419 void dma_direct_sync_sg_for_cpu(struct device *dev,
420 struct scatterlist *sgl, int nents, enum dma_data_direction dir)
421 {
422 struct scatterlist *sg;
423 int i;
424
425 for_each_sg(sgl, sg, nents, i) {
426 phys_addr_t paddr = dma_to_phys(dev, sg_dma_address(sg));
427
428 if (!dev_is_dma_coherent(dev))
429 arch_sync_dma_for_cpu(paddr, sg->length, dir);
430
431 swiotlb_sync_single_for_cpu(dev, paddr, sg->length, dir);
432
433 if (dir == DMA_FROM_DEVICE)
434 arch_dma_mark_clean(paddr, sg->length);
435 }
436
437 if (!dev_is_dma_coherent(dev))
438 arch_sync_dma_for_cpu_all();
439 }
440
441 /*
442 * Unmaps segments, except for ones marked as pci_p2pdma which do not
443 * require any further action as they contain a bus address.
444 */
445 void dma_direct_unmap_sg(struct device *dev, struct scatterlist *sgl,
446 int nents, enum dma_data_direction dir, unsigned long attrs)
447 {
448 struct scatterlist *sg;
449 int i;
450
451 for_each_sg(sgl, sg, nents, i) {
452 if (sg_dma_is_bus_address(sg))
453 sg_dma_unmark_bus_address(sg);
454 else
455 dma_direct_unmap_page(dev, sg->dma_address,
456 sg_dma_len(sg), dir, attrs);
457 }
458 }
459 #endif
460
461 int dma_direct_map_sg(struct device *dev, struct scatterlist *sgl, int nents,
462 enum dma_data_direction dir, unsigned long attrs)
463 {
464 struct pci_p2pdma_map_state p2pdma_state = {};
465 enum pci_p2pdma_map_type map;
466 struct scatterlist *sg;
467 int i, ret;
468
469 for_each_sg(sgl, sg, nents, i) {
470 if (is_pci_p2pdma_page(sg_page(sg))) {
471 map = pci_p2pdma_map_segment(&p2pdma_state, dev, sg);
472 switch (map) {
473 case PCI_P2PDMA_MAP_BUS_ADDR:
474 continue;
475 case PCI_P2PDMA_MAP_THRU_HOST_BRIDGE:
476 /*
477 * Any P2P mapping that traverses the PCI
478 * host bridge must be mapped with CPU physical
479 * address and not PCI bus addresses. This is
480 * done with dma_direct_map_page() below.
481 */
482 break;
483 default:
484 ret = -EREMOTEIO;
485 goto out_unmap;
486 }
487 }
488
489 sg->dma_address = dma_direct_map_page(dev, sg_page(sg),
490 sg->offset, sg->length, dir, attrs);
491 if (sg->dma_address == DMA_MAPPING_ERROR) {
492 ret = -EIO;
493 goto out_unmap;
494 }
495 sg_dma_len(sg) = sg->length;
496 }
497
498 return nents;
499
500 out_unmap:
501 dma_direct_unmap_sg(dev, sgl, i, dir, attrs | DMA_ATTR_SKIP_CPU_SYNC);
502 return ret;
503 }
504
505 dma_addr_t dma_direct_map_resource(struct device *dev, phys_addr_t paddr,
506 size_t size, enum dma_data_direction dir, unsigned long attrs)
507 {
508 dma_addr_t dma_addr = paddr;
509
510 if (unlikely(!dma_capable(dev, dma_addr, size, false))) {
511 dev_err_once(dev,
512 "DMA addr %pad+%zu overflow (mask %llx, bus limit %llx).\n",
513 &dma_addr, size, *dev->dma_mask, dev->bus_dma_limit);
514 WARN_ON_ONCE(1);
515 return DMA_MAPPING_ERROR;
516 }
517
518 return dma_addr;
519 }
520
521 int dma_direct_get_sgtable(struct device *dev, struct sg_table *sgt,
522 void *cpu_addr, dma_addr_t dma_addr, size_t size,
523 unsigned long attrs)
524 {
525 struct page *page = dma_direct_to_page(dev, dma_addr);
526 int ret;
527
528 ret = sg_alloc_table(sgt, 1, GFP_KERNEL);
529 if (!ret)
530 sg_set_page(sgt->sgl, page, PAGE_ALIGN(size), 0);
531 return ret;
532 }
533
534 bool dma_direct_can_mmap(struct device *dev)
535 {
536 return dev_is_dma_coherent(dev) ||
537 IS_ENABLED(CONFIG_DMA_NONCOHERENT_MMAP);
538 }
539
540 int dma_direct_mmap(struct device *dev, struct vm_area_struct *vma,
541 void *cpu_addr, dma_addr_t dma_addr, size_t size,
542 unsigned long attrs)
543 {
544 unsigned long user_count = vma_pages(vma);
545 unsigned long count = PAGE_ALIGN(size) >> PAGE_SHIFT;
546 unsigned long pfn = PHYS_PFN(dma_to_phys(dev, dma_addr));
547 int ret = -ENXIO;
548
549 vma->vm_page_prot = dma_pgprot(dev, vma->vm_page_prot, attrs);
550 if (force_dma_unencrypted(dev))
551 vma->vm_page_prot = pgprot_decrypted(vma->vm_page_prot);
552
553 if (dma_mmap_from_dev_coherent(dev, vma, cpu_addr, size, &ret))
554 return ret;
555 if (dma_mmap_from_global_coherent(vma, cpu_addr, size, &ret))
556 return ret;
557
558 if (vma->vm_pgoff >= count || user_count > count - vma->vm_pgoff)
559 return -ENXIO;
560 return remap_pfn_range(vma, vma->vm_start, pfn + vma->vm_pgoff,
561 user_count << PAGE_SHIFT, vma->vm_page_prot);
562 }
563
564 int dma_direct_supported(struct device *dev, u64 mask)
565 {
566 u64 min_mask = (max_pfn - 1) << PAGE_SHIFT;
567
568 /*
569 * Because 32-bit DMA masks are so common we expect every architecture
570 * to be able to satisfy them - either by not supporting more physical
571 * memory, or by providing a ZONE_DMA32. If neither is the case, the
572 * architecture needs to use an IOMMU instead of the direct mapping.
573 */
574 if (mask >= DMA_BIT_MASK(32))
575 return 1;
576
577 /*
578 * This check needs to be against the actual bit mask value, so use
579 * phys_to_dma_unencrypted() here so that the SME encryption mask isn't
580 * part of the check.
581 */
582 if (IS_ENABLED(CONFIG_ZONE_DMA))
583 min_mask = min_t(u64, min_mask, DMA_BIT_MASK(zone_dma_bits));
584 return mask >= phys_to_dma_unencrypted(dev, min_mask);
585 }
586
587 /*
588 * To check whether all ram resource ranges are covered by dma range map
589 * Returns 0 when further check is needed
590 * Returns 1 if there is some RAM range can't be covered by dma_range_map
591 */
592 static int check_ram_in_range_map(unsigned long start_pfn,
593 unsigned long nr_pages, void *data)
594 {
595 unsigned long end_pfn = start_pfn + nr_pages;
596 const struct bus_dma_region *bdr = NULL;
597 const struct bus_dma_region *m;
598 struct device *dev = data;
599
600 while (start_pfn < end_pfn) {
601 for (m = dev->dma_range_map; PFN_DOWN(m->size); m++) {
602 unsigned long cpu_start_pfn = PFN_DOWN(m->cpu_start);
603
604 if (start_pfn >= cpu_start_pfn &&
605 start_pfn - cpu_start_pfn < PFN_DOWN(m->size)) {
606 bdr = m;
607 break;
608 }
609 }
610 if (!bdr)
611 return 1;
612
613 start_pfn = PFN_DOWN(bdr->cpu_start) + PFN_DOWN(bdr->size);
614 }
615
616 return 0;
617 }
618
619 bool dma_direct_all_ram_mapped(struct device *dev)
620 {
621 if (!dev->dma_range_map)
622 return true;
623 return !walk_system_ram_range(0, PFN_DOWN(ULONG_MAX) + 1, dev,
624 check_ram_in_range_map);
625 }
626
627 size_t dma_direct_max_mapping_size(struct device *dev)
628 {
629 /* If SWIOTLB is active, use its maximum mapping size */
630 if (is_swiotlb_active(dev) &&
631 (dma_addressing_limited(dev) || is_swiotlb_force_bounce(dev)))
632 return swiotlb_max_mapping_size(dev);
633 return SIZE_MAX;
634 }
635
636 bool dma_direct_need_sync(struct device *dev, dma_addr_t dma_addr)
637 {
638 return !dev_is_dma_coherent(dev) ||
639 swiotlb_find_pool(dev, dma_to_phys(dev, dma_addr));
640 }
641
642 /**
643 * dma_direct_set_offset - Assign scalar offset for a single DMA range.
644 * @dev: device pointer; needed to "own" the alloced memory.
645 * @cpu_start: beginning of memory region covered by this offset.
646 * @dma_start: beginning of DMA/PCI region covered by this offset.
647 * @size: size of the region.
648 *
649 * This is for the simple case of a uniform offset which cannot
650 * be discovered by "dma-ranges".
651 *
652 * It returns -ENOMEM if out of memory, -EINVAL if a map
653 * already exists, 0 otherwise.
654 *
655 * Note: any call to this from a driver is a bug. The mapping needs
656 * to be described by the device tree or other firmware interfaces.
657 */
658 int dma_direct_set_offset(struct device *dev, phys_addr_t cpu_start,
659 dma_addr_t dma_start, u64 size)
660 {
661 struct bus_dma_region *map;
662 u64 offset = (u64)cpu_start - (u64)dma_start;
663
664 if (dev->dma_range_map) {
665 dev_err(dev, "attempt to add DMA range to existing map\n");
666 return -EINVAL;
667 }
668
669 if (!offset)
670 return 0;
671
672 map = kcalloc(2, sizeof(*map), GFP_KERNEL);
673 if (!map)
674 return -ENOMEM;
675 map[0].cpu_start = cpu_start;
676 map[0].dma_start = dma_start;
677 map[0].size = size;
678 dev->dma_range_map = map;
679 return 0;
680 }
681
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