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  1/*
  2 * Copyright 2010 Tilera Corporation. All Rights Reserved.
  3 *
  4 *   This program is free software; you can redistribute it and/or
  5 *   modify it under the terms of the GNU General Public License
  6 *   as published by the Free Software Foundation, version 2.
  7 *
  8 *   This program is distributed in the hope that it will be useful, but
  9 *   WITHOUT ANY WARRANTY; without even the implied warranty of
 10 *   MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE, GOOD TITLE or
 11 *   NON INFRINGEMENT.  See the GNU General Public License for
 12 *   more details.
 13 */
 14
 15#include <linux/mm.h>
 16#include <linux/dma-mapping.h>
 17#include <linux/swiotlb.h>
 18#include <linux/vmalloc.h>
 19#include <linux/export.h>
 20#include <asm/tlbflush.h>
 21#include <asm/homecache.h>
 22
 23/* Generic DMA mapping functions: */
 24
 25/*
 26 * Allocate what Linux calls "coherent" memory.  On TILEPro this is
 27 * uncached memory; on TILE-Gx it is hash-for-home memory.
 28 */
 29#ifdef __tilepro__
 30#define PAGE_HOME_DMA PAGE_HOME_UNCACHED
 31#else
 32#define PAGE_HOME_DMA PAGE_HOME_HASH
 33#endif
 34
 35static void *tile_dma_alloc_coherent(struct device *dev, size_t size,
 36				     dma_addr_t *dma_handle, gfp_t gfp,
 37				     unsigned long attrs)
 38{
 39	u64 dma_mask = (dev && dev->coherent_dma_mask) ?
 40		dev->coherent_dma_mask : DMA_BIT_MASK(32);
 41	int node = dev ? dev_to_node(dev) : 0;
 42	int order = get_order(size);
 43	struct page *pg;
 44	dma_addr_t addr;
 45
 46	gfp |= __GFP_ZERO;
 47
 48	/*
 49	 * If the mask specifies that the memory be in the first 4 GB, then
 50	 * we force the allocation to come from the DMA zone.  We also
 51	 * force the node to 0 since that's the only node where the DMA
 52	 * zone isn't empty.  If the mask size is smaller than 32 bits, we
 53	 * may still not be able to guarantee a suitable memory address, in
 54	 * which case we will return NULL.  But such devices are uncommon.
 55	 */
 56	if (dma_mask <= DMA_BIT_MASK(32)) {
 57		gfp |= GFP_DMA;
 58		node = 0;
 59	}
 60
 61	pg = homecache_alloc_pages_node(node, gfp, order, PAGE_HOME_DMA);
 62	if (pg == NULL)
 63		return NULL;
 64
 65	addr = page_to_phys(pg);
 66	if (addr + size > dma_mask) {
 67		__homecache_free_pages(pg, order);
 68		return NULL;
 69	}
 70
 71	*dma_handle = addr;
 72
 73	return page_address(pg);
 74}
 75
 76/*
 77 * Free memory that was allocated with tile_dma_alloc_coherent.
 78 */
 79static void tile_dma_free_coherent(struct device *dev, size_t size,
 80				   void *vaddr, dma_addr_t dma_handle,
 81				   unsigned long attrs)
 82{
 83	homecache_free_pages((unsigned long)vaddr, get_order(size));
 84}
 85
 86/*
 87 * The map routines "map" the specified address range for DMA
 88 * accesses.  The memory belongs to the device after this call is
 89 * issued, until it is unmapped with dma_unmap_single.
 90 *
 91 * We don't need to do any mapping, we just flush the address range
 92 * out of the cache and return a DMA address.
 93 *
 94 * The unmap routines do whatever is necessary before the processor
 95 * accesses the memory again, and must be called before the driver
 96 * touches the memory.  We can get away with a cache invalidate if we
 97 * can count on nothing having been touched.
 98 */
 99
100/* Set up a single page for DMA access. */
101static void __dma_prep_page(struct page *page, unsigned long offset,
102			    size_t size, enum dma_data_direction direction)
103{
104	/*
105	 * Flush the page from cache if necessary.
106	 * On tilegx, data is delivered to hash-for-home L3; on tilepro,
107	 * data is delivered direct to memory.
108	 *
109	 * NOTE: If we were just doing DMA_TO_DEVICE we could optimize
110	 * this to be a "flush" not a "finv" and keep some of the
111	 * state in cache across the DMA operation, but it doesn't seem
112	 * worth creating the necessary flush_buffer_xxx() infrastructure.
113	 */
114	int home = page_home(page);
115	switch (home) {
116	case PAGE_HOME_HASH:
117#ifdef __tilegx__
118		return;
119#endif
120		break;
121	case PAGE_HOME_UNCACHED:
122#ifdef __tilepro__
123		return;
124#endif
125		break;
126	case PAGE_HOME_IMMUTABLE:
127		/* Should be going to the device only. */
128		BUG_ON(direction == DMA_FROM_DEVICE ||
129		       direction == DMA_BIDIRECTIONAL);
130		return;
131	case PAGE_HOME_INCOHERENT:
132		/* Incoherent anyway, so no need to work hard here. */
133		return;
134	default:
135		BUG_ON(home < 0 || home >= NR_CPUS);
136		break;
137	}
138	homecache_finv_page(page);
139
140#ifdef DEBUG_ALIGNMENT
141	/* Warn if the region isn't cacheline aligned. */
142	if (offset & (L2_CACHE_BYTES - 1) || (size & (L2_CACHE_BYTES - 1)))
143		pr_warn("Unaligned DMA to non-hfh memory: PA %#llx/%#lx\n",
144			PFN_PHYS(page_to_pfn(page)) + offset, size);
145#endif
146}
147
148/* Make the page ready to be read by the core. */
149static void __dma_complete_page(struct page *page, unsigned long offset,
150				size_t size, enum dma_data_direction direction)
151{
152#ifdef __tilegx__
153	switch (page_home(page)) {
154	case PAGE_HOME_HASH:
155		/* I/O device delivered data the way the cpu wanted it. */
156		break;
157	case PAGE_HOME_INCOHERENT:
158		/* Incoherent anyway, so no need to work hard here. */
159		break;
160	case PAGE_HOME_IMMUTABLE:
161		/* Extra read-only copies are not a problem. */
162		break;
163	default:
164		/* Flush the bogus hash-for-home I/O entries to memory. */
165		homecache_finv_map_page(page, PAGE_HOME_HASH);
166		break;
167	}
168#endif
169}
170
171static void __dma_prep_pa_range(dma_addr_t dma_addr, size_t size,
172				enum dma_data_direction direction)
173{
174	struct page *page = pfn_to_page(PFN_DOWN(dma_addr));
175	unsigned long offset = dma_addr & (PAGE_SIZE - 1);
176	size_t bytes = min(size, (size_t)(PAGE_SIZE - offset));
177
178	while (size != 0) {
179		__dma_prep_page(page, offset, bytes, direction);
180		size -= bytes;
181		++page;
182		offset = 0;
183		bytes = min((size_t)PAGE_SIZE, size);
184	}
185}
186
187static void __dma_complete_pa_range(dma_addr_t dma_addr, size_t size,
188				    enum dma_data_direction direction)
189{
190	struct page *page = pfn_to_page(PFN_DOWN(dma_addr));
191	unsigned long offset = dma_addr & (PAGE_SIZE - 1);
192	size_t bytes = min(size, (size_t)(PAGE_SIZE - offset));
193
194	while (size != 0) {
195		__dma_complete_page(page, offset, bytes, direction);
196		size -= bytes;
197		++page;
198		offset = 0;
199		bytes = min((size_t)PAGE_SIZE, size);
200	}
201}
202
203static int tile_dma_map_sg(struct device *dev, struct scatterlist *sglist,
204			   int nents, enum dma_data_direction direction,
205			   unsigned long attrs)
206{
207	struct scatterlist *sg;
208	int i;
209
210	BUG_ON(!valid_dma_direction(direction));
211
212	WARN_ON(nents == 0 || sglist->length == 0);
213
214	for_each_sg(sglist, sg, nents, i) {
215		sg->dma_address = sg_phys(sg);
216#ifdef CONFIG_NEED_SG_DMA_LENGTH
217		sg->dma_length = sg->length;
218#endif
219		if (attrs & DMA_ATTR_SKIP_CPU_SYNC)
220			continue;
221		__dma_prep_pa_range(sg->dma_address, sg->length, direction);
222	}
223
224	return nents;
225}
226
227static void tile_dma_unmap_sg(struct device *dev, struct scatterlist *sglist,
228			      int nents, enum dma_data_direction direction,
229			      unsigned long attrs)
230{
231	struct scatterlist *sg;
232	int i;
233
234	BUG_ON(!valid_dma_direction(direction));
235	for_each_sg(sglist, sg, nents, i) {
236		sg->dma_address = sg_phys(sg);
237		if (attrs & DMA_ATTR_SKIP_CPU_SYNC)
238			continue;
239		__dma_complete_pa_range(sg->dma_address, sg->length,
240					direction);
241	}
242}
243
244static dma_addr_t tile_dma_map_page(struct device *dev, struct page *page,
245				    unsigned long offset, size_t size,
246				    enum dma_data_direction direction,
247				    unsigned long attrs)
248{
249	BUG_ON(!valid_dma_direction(direction));
250
251	BUG_ON(offset + size > PAGE_SIZE);
252	if (!(attrs & DMA_ATTR_SKIP_CPU_SYNC))
253		__dma_prep_page(page, offset, size, direction);
254
255	return page_to_pa(page) + offset;
256}
257
258static void tile_dma_unmap_page(struct device *dev, dma_addr_t dma_address,
259				size_t size, enum dma_data_direction direction,
260				unsigned long attrs)
261{
262	BUG_ON(!valid_dma_direction(direction));
263
264	if (attrs & DMA_ATTR_SKIP_CPU_SYNC)
265		return;
266
267	__dma_complete_page(pfn_to_page(PFN_DOWN(dma_address)),
268			    dma_address & (PAGE_SIZE - 1), size, direction);
269}
270
271static void tile_dma_sync_single_for_cpu(struct device *dev,
272					 dma_addr_t dma_handle,
273					 size_t size,
274					 enum dma_data_direction direction)
275{
276	BUG_ON(!valid_dma_direction(direction));
277
278	__dma_complete_pa_range(dma_handle, size, direction);
279}
280
281static void tile_dma_sync_single_for_device(struct device *dev,
282					    dma_addr_t dma_handle, size_t size,
283					    enum dma_data_direction direction)
284{
285	__dma_prep_pa_range(dma_handle, size, direction);
286}
287
288static void tile_dma_sync_sg_for_cpu(struct device *dev,
289				     struct scatterlist *sglist, int nelems,
290				     enum dma_data_direction direction)
291{
292	struct scatterlist *sg;
293	int i;
294
295	BUG_ON(!valid_dma_direction(direction));
296	WARN_ON(nelems == 0 || sglist->length == 0);
297
298	for_each_sg(sglist, sg, nelems, i) {
299		dma_sync_single_for_cpu(dev, sg->dma_address,
300					sg_dma_len(sg), direction);
301	}
302}
303
304static void tile_dma_sync_sg_for_device(struct device *dev,
305					struct scatterlist *sglist, int nelems,
306					enum dma_data_direction direction)
307{
308	struct scatterlist *sg;
309	int i;
310
311	BUG_ON(!valid_dma_direction(direction));
312	WARN_ON(nelems == 0 || sglist->length == 0);
313
314	for_each_sg(sglist, sg, nelems, i) {
315		dma_sync_single_for_device(dev, sg->dma_address,
316					   sg_dma_len(sg), direction);
317	}
318}
319
320static inline int
321tile_dma_mapping_error(struct device *dev, dma_addr_t dma_addr)
322{
323	return 0;
324}
325
326static inline int
327tile_dma_supported(struct device *dev, u64 mask)
328{
329	return 1;
330}
331
332static struct dma_map_ops tile_default_dma_map_ops = {
333	.alloc = tile_dma_alloc_coherent,
334	.free = tile_dma_free_coherent,
335	.map_page = tile_dma_map_page,
336	.unmap_page = tile_dma_unmap_page,
337	.map_sg = tile_dma_map_sg,
338	.unmap_sg = tile_dma_unmap_sg,
339	.sync_single_for_cpu = tile_dma_sync_single_for_cpu,
340	.sync_single_for_device = tile_dma_sync_single_for_device,
341	.sync_sg_for_cpu = tile_dma_sync_sg_for_cpu,
342	.sync_sg_for_device = tile_dma_sync_sg_for_device,
343	.mapping_error = tile_dma_mapping_error,
344	.dma_supported = tile_dma_supported
345};
346
347struct dma_map_ops *tile_dma_map_ops = &tile_default_dma_map_ops;
348EXPORT_SYMBOL(tile_dma_map_ops);
349
350/* Generic PCI DMA mapping functions */
351
352static void *tile_pci_dma_alloc_coherent(struct device *dev, size_t size,
353					 dma_addr_t *dma_handle, gfp_t gfp,
354					 unsigned long attrs)
355{
356	int node = dev_to_node(dev);
357	int order = get_order(size);
358	struct page *pg;
359	dma_addr_t addr;
360
361	gfp |= __GFP_ZERO;
362
363	pg = homecache_alloc_pages_node(node, gfp, order, PAGE_HOME_DMA);
364	if (pg == NULL)
365		return NULL;
366
367	addr = page_to_phys(pg);
368
369	*dma_handle = addr + get_dma_offset(dev);
370
371	return page_address(pg);
372}
373
374/*
375 * Free memory that was allocated with tile_pci_dma_alloc_coherent.
376 */
377static void tile_pci_dma_free_coherent(struct device *dev, size_t size,
378				       void *vaddr, dma_addr_t dma_handle,
379				       unsigned long attrs)
380{
381	homecache_free_pages((unsigned long)vaddr, get_order(size));
382}
383
384static int tile_pci_dma_map_sg(struct device *dev, struct scatterlist *sglist,
385			       int nents, enum dma_data_direction direction,
386			       unsigned long attrs)
387{
388	struct scatterlist *sg;
389	int i;
390
391	BUG_ON(!valid_dma_direction(direction));
392
393	WARN_ON(nents == 0 || sglist->length == 0);
394
395	for_each_sg(sglist, sg, nents, i) {
396		sg->dma_address = sg_phys(sg);
397		__dma_prep_pa_range(sg->dma_address, sg->length, direction);
398
399		sg->dma_address = sg->dma_address + get_dma_offset(dev);
400#ifdef CONFIG_NEED_SG_DMA_LENGTH
401		sg->dma_length = sg->length;
402#endif
403	}
404
405	return nents;
406}
407
408static void tile_pci_dma_unmap_sg(struct device *dev,
409				  struct scatterlist *sglist, int nents,
410				  enum dma_data_direction direction,
411				  unsigned long attrs)
412{
413	struct scatterlist *sg;
414	int i;
415
416	BUG_ON(!valid_dma_direction(direction));
417	for_each_sg(sglist, sg, nents, i) {
418		sg->dma_address = sg_phys(sg);
419		__dma_complete_pa_range(sg->dma_address, sg->length,
420					direction);
421	}
422}
423
424static dma_addr_t tile_pci_dma_map_page(struct device *dev, struct page *page,
425					unsigned long offset, size_t size,
426					enum dma_data_direction direction,
427					unsigned long attrs)
428{
429	BUG_ON(!valid_dma_direction(direction));
430
431	BUG_ON(offset + size > PAGE_SIZE);
432	__dma_prep_page(page, offset, size, direction);
433
434	return page_to_pa(page) + offset + get_dma_offset(dev);
435}
436
437static void tile_pci_dma_unmap_page(struct device *dev, dma_addr_t dma_address,
438				    size_t size,
439				    enum dma_data_direction direction,
440				    unsigned long attrs)
441{
442	BUG_ON(!valid_dma_direction(direction));
443
444	dma_address -= get_dma_offset(dev);
445
446	__dma_complete_page(pfn_to_page(PFN_DOWN(dma_address)),
447			    dma_address & (PAGE_SIZE - 1), size, direction);
448}
449
450static void tile_pci_dma_sync_single_for_cpu(struct device *dev,
451					     dma_addr_t dma_handle,
452					     size_t size,
453					     enum dma_data_direction direction)
454{
455	BUG_ON(!valid_dma_direction(direction));
456
457	dma_handle -= get_dma_offset(dev);
458
459	__dma_complete_pa_range(dma_handle, size, direction);
460}
461
462static void tile_pci_dma_sync_single_for_device(struct device *dev,
463						dma_addr_t dma_handle,
464						size_t size,
465						enum dma_data_direction
466						direction)
467{
468	dma_handle -= get_dma_offset(dev);
469
470	__dma_prep_pa_range(dma_handle, size, direction);
471}
472
473static void tile_pci_dma_sync_sg_for_cpu(struct device *dev,
474					 struct scatterlist *sglist,
475					 int nelems,
476					 enum dma_data_direction direction)
477{
478	struct scatterlist *sg;
479	int i;
480
481	BUG_ON(!valid_dma_direction(direction));
482	WARN_ON(nelems == 0 || sglist->length == 0);
483
484	for_each_sg(sglist, sg, nelems, i) {
485		dma_sync_single_for_cpu(dev, sg->dma_address,
486					sg_dma_len(sg), direction);
487	}
488}
489
490static void tile_pci_dma_sync_sg_for_device(struct device *dev,
491					    struct scatterlist *sglist,
492					    int nelems,
493					    enum dma_data_direction direction)
494{
495	struct scatterlist *sg;
496	int i;
497
498	BUG_ON(!valid_dma_direction(direction));
499	WARN_ON(nelems == 0 || sglist->length == 0);
500
501	for_each_sg(sglist, sg, nelems, i) {
502		dma_sync_single_for_device(dev, sg->dma_address,
503					   sg_dma_len(sg), direction);
504	}
505}
506
507static inline int
508tile_pci_dma_mapping_error(struct device *dev, dma_addr_t dma_addr)
509{
510	return 0;
511}
512
513static inline int
514tile_pci_dma_supported(struct device *dev, u64 mask)
515{
516	return 1;
517}
518
519static struct dma_map_ops tile_pci_default_dma_map_ops = {
520	.alloc = tile_pci_dma_alloc_coherent,
521	.free = tile_pci_dma_free_coherent,
522	.map_page = tile_pci_dma_map_page,
523	.unmap_page = tile_pci_dma_unmap_page,
524	.map_sg = tile_pci_dma_map_sg,
525	.unmap_sg = tile_pci_dma_unmap_sg,
526	.sync_single_for_cpu = tile_pci_dma_sync_single_for_cpu,
527	.sync_single_for_device = tile_pci_dma_sync_single_for_device,
528	.sync_sg_for_cpu = tile_pci_dma_sync_sg_for_cpu,
529	.sync_sg_for_device = tile_pci_dma_sync_sg_for_device,
530	.mapping_error = tile_pci_dma_mapping_error,
531	.dma_supported = tile_pci_dma_supported
532};
533
534struct dma_map_ops *gx_pci_dma_map_ops = &tile_pci_default_dma_map_ops;
535EXPORT_SYMBOL(gx_pci_dma_map_ops);
536
537/* PCI DMA mapping functions for legacy PCI devices */
538
539#ifdef CONFIG_SWIOTLB
540static void *tile_swiotlb_alloc_coherent(struct device *dev, size_t size,
541					 dma_addr_t *dma_handle, gfp_t gfp,
542					 unsigned long attrs)
543{
544	gfp |= GFP_DMA;
545	return swiotlb_alloc_coherent(dev, size, dma_handle, gfp);
546}
547
548static void tile_swiotlb_free_coherent(struct device *dev, size_t size,
549				       void *vaddr, dma_addr_t dma_addr,
550				       unsigned long attrs)
551{
552	swiotlb_free_coherent(dev, size, vaddr, dma_addr);
553}
554
555static struct dma_map_ops pci_swiotlb_dma_ops = {
556	.alloc = tile_swiotlb_alloc_coherent,
557	.free = tile_swiotlb_free_coherent,
558	.map_page = swiotlb_map_page,
559	.unmap_page = swiotlb_unmap_page,
560	.map_sg = swiotlb_map_sg_attrs,
561	.unmap_sg = swiotlb_unmap_sg_attrs,
562	.sync_single_for_cpu = swiotlb_sync_single_for_cpu,
563	.sync_single_for_device = swiotlb_sync_single_for_device,
564	.sync_sg_for_cpu = swiotlb_sync_sg_for_cpu,
565	.sync_sg_for_device = swiotlb_sync_sg_for_device,
566	.dma_supported = swiotlb_dma_supported,
567	.mapping_error = swiotlb_dma_mapping_error,
568};
569
570static struct dma_map_ops pci_hybrid_dma_ops = {
571	.alloc = tile_swiotlb_alloc_coherent,
572	.free = tile_swiotlb_free_coherent,
573	.map_page = tile_pci_dma_map_page,
574	.unmap_page = tile_pci_dma_unmap_page,
575	.map_sg = tile_pci_dma_map_sg,
576	.unmap_sg = tile_pci_dma_unmap_sg,
577	.sync_single_for_cpu = tile_pci_dma_sync_single_for_cpu,
578	.sync_single_for_device = tile_pci_dma_sync_single_for_device,
579	.sync_sg_for_cpu = tile_pci_dma_sync_sg_for_cpu,
580	.sync_sg_for_device = tile_pci_dma_sync_sg_for_device,
581	.mapping_error = tile_pci_dma_mapping_error,
582	.dma_supported = tile_pci_dma_supported
583};
584
585struct dma_map_ops *gx_legacy_pci_dma_map_ops = &pci_swiotlb_dma_ops;
586struct dma_map_ops *gx_hybrid_pci_dma_map_ops = &pci_hybrid_dma_ops;
587#else
588struct dma_map_ops *gx_legacy_pci_dma_map_ops;
589struct dma_map_ops *gx_hybrid_pci_dma_map_ops;
590#endif
591EXPORT_SYMBOL(gx_legacy_pci_dma_map_ops);
592EXPORT_SYMBOL(gx_hybrid_pci_dma_map_ops);
593
594int dma_set_mask(struct device *dev, u64 mask)
595{
596	struct dma_map_ops *dma_ops = get_dma_ops(dev);
597
598	/*
599	 * For PCI devices with 64-bit DMA addressing capability, promote
600	 * the dma_ops to hybrid, with the consistent memory DMA space limited
601	 * to 32-bit. For 32-bit capable devices, limit the streaming DMA
602	 * address range to max_direct_dma_addr.
603	 */
604	if (dma_ops == gx_pci_dma_map_ops ||
605	    dma_ops == gx_hybrid_pci_dma_map_ops ||
606	    dma_ops == gx_legacy_pci_dma_map_ops) {
607		if (mask == DMA_BIT_MASK(64) &&
608		    dma_ops == gx_legacy_pci_dma_map_ops)
609			set_dma_ops(dev, gx_hybrid_pci_dma_map_ops);
610		else if (mask > dev->archdata.max_direct_dma_addr)
611			mask = dev->archdata.max_direct_dma_addr;
612	}
613
614	if (!dev->dma_mask || !dma_supported(dev, mask))
615		return -EIO;
616
617	*dev->dma_mask = mask;
618
619	return 0;
620}
621EXPORT_SYMBOL(dma_set_mask);
622
623#ifdef CONFIG_ARCH_HAS_DMA_SET_COHERENT_MASK
624int dma_set_coherent_mask(struct device *dev, u64 mask)
625{
626	struct dma_map_ops *dma_ops = get_dma_ops(dev);
627
628	/*
629	 * For PCI devices with 64-bit DMA addressing capability, promote
630	 * the dma_ops to full capability for both streams and consistent
631	 * memory access. For 32-bit capable devices, limit the consistent 
632	 * memory DMA range to max_direct_dma_addr.
633	 */
634	if (dma_ops == gx_pci_dma_map_ops ||
635	    dma_ops == gx_hybrid_pci_dma_map_ops ||
636	    dma_ops == gx_legacy_pci_dma_map_ops) {
637		if (mask == DMA_BIT_MASK(64))
638			set_dma_ops(dev, gx_pci_dma_map_ops);
639		else if (mask > dev->archdata.max_direct_dma_addr)
640			mask = dev->archdata.max_direct_dma_addr;
641	}
642
643	if (!dma_supported(dev, mask))
644		return -EIO;
645	dev->coherent_dma_mask = mask;
646	return 0;
647}
648EXPORT_SYMBOL(dma_set_coherent_mask);
649#endif
650
651#ifdef ARCH_HAS_DMA_GET_REQUIRED_MASK
652/*
653 * The generic dma_get_required_mask() uses the highest physical address
654 * (max_pfn) to provide the hint to the PCI drivers regarding 32-bit or
655 * 64-bit DMA configuration. Since TILEGx has I/O TLB/MMU, allowing the
656 * DMAs to use the full 64-bit PCI address space and not limited by
657 * the physical memory space, we always let the PCI devices use
658 * 64-bit DMA if they have that capability, by returning the 64-bit
659 * DMA mask here. The device driver has the option to use 32-bit DMA if
660 * the device is not capable of 64-bit DMA.
661 */
662u64 dma_get_required_mask(struct device *dev)
663{
664	return DMA_BIT_MASK(64);
665}
666EXPORT_SYMBOL_GPL(dma_get_required_mask);
667#endif