1/*
  2 * Dynamic DMA mapping support for AMD Hammer.
  3 *
  4 * Use the integrated AGP GART in the Hammer northbridge as an IOMMU for PCI.
  5 * This allows to use PCI devices that only support 32bit addresses on systems
  6 * with more than 4GB.
  7 *
  8 * See Documentation/PCI/PCI-DMA-mapping.txt for the interface specification.
  9 *
 10 * Copyright 2002 Andi Kleen, SuSE Labs.
 11 * Subject to the GNU General Public License v2 only.
 12 */
 13
 14#include <linux/types.h>
 15#include <linux/ctype.h>
 16#include <linux/agp_backend.h>
 17#include <linux/init.h>
 18#include <linux/mm.h>
 19#include <linux/sched.h>
 20#include <linux/string.h>
 21#include <linux/spinlock.h>
 22#include <linux/pci.h>
 23#include <linux/module.h>
 24#include <linux/topology.h>
 25#include <linux/interrupt.h>
 26#include <linux/bitmap.h>
 27#include <linux/kdebug.h>
 28#include <linux/scatterlist.h>
 29#include <linux/iommu-helper.h>
 30#include <linux/syscore_ops.h>
 31#include <linux/io.h>
 32#include <linux/gfp.h>
 33#include <linux/atomic.h>
 34#include <asm/mtrr.h>
 35#include <asm/pgtable.h>
 36#include <asm/proto.h>
 37#include <asm/iommu.h>
 38#include <asm/gart.h>
 39#include <asm/cacheflush.h>
 40#include <asm/swiotlb.h>
 41#include <asm/dma.h>
 42#include <asm/amd_nb.h>
 43#include <asm/x86_init.h>
 44#include <asm/iommu_table.h>
 45
 46static unsigned long iommu_bus_base;	/* GART remapping area (physical) */
 47static unsigned long iommu_size;	/* size of remapping area bytes */
 48static unsigned long iommu_pages;	/* .. and in pages */
 49
 50static u32 *iommu_gatt_base;		/* Remapping table */
 51
 52static dma_addr_t bad_dma_addr;
 53
 54/*
 55 * If this is disabled the IOMMU will use an optimized flushing strategy
 56 * of only flushing when an mapping is reused. With it true the GART is
 57 * flushed for every mapping. Problem is that doing the lazy flush seems
 58 * to trigger bugs with some popular PCI cards, in particular 3ware (but
 59 * has been also also seen with Qlogic at least).
 60 */
 61static int iommu_fullflush = 1;
 62
 63/* Allocation bitmap for the remapping area: */
 64static DEFINE_SPINLOCK(iommu_bitmap_lock);
 65/* Guarded by iommu_bitmap_lock: */
 66static unsigned long *iommu_gart_bitmap;
 67
 68static u32 gart_unmapped_entry;
 69
 70#define GPTE_VALID    1
 71#define GPTE_COHERENT 2
 72#define GPTE_ENCODE(x) \
 73	(((x) & 0xfffff000) | (((x) >> 32) << 4) | GPTE_VALID | GPTE_COHERENT)
 74#define GPTE_DECODE(x) (((x) & 0xfffff000) | (((u64)(x) & 0xff0) << 28))
 75
 76#define EMERGENCY_PAGES 32 /* = 128KB */
 77
 78#ifdef CONFIG_AGP
 79#define AGPEXTERN extern
 80#else
 81#define AGPEXTERN
 82#endif
 83
 84/* GART can only remap to physical addresses < 1TB */
 85#define GART_MAX_PHYS_ADDR	(1ULL << 40)
 86
 87/* backdoor interface to AGP driver */
 88AGPEXTERN int agp_memory_reserved;
 89AGPEXTERN __u32 *agp_gatt_table;
 90
 91static unsigned long next_bit;  /* protected by iommu_bitmap_lock */
 92static bool need_flush;		/* global flush state. set for each gart wrap */
 93
 94static unsigned long alloc_iommu(struct device *dev, int size,
 95				 unsigned long align_mask)
 96{
 97	unsigned long offset, flags;
 98	unsigned long boundary_size;
 99	unsigned long base_index;
100
101	base_index = ALIGN(iommu_bus_base & dma_get_seg_boundary(dev),
102			   PAGE_SIZE) >> PAGE_SHIFT;
103	boundary_size = ALIGN((u64)dma_get_seg_boundary(dev) + 1,
104			      PAGE_SIZE) >> PAGE_SHIFT;
105
106	spin_lock_irqsave(&iommu_bitmap_lock, flags);
107	offset = iommu_area_alloc(iommu_gart_bitmap, iommu_pages, next_bit,
108				  size, base_index, boundary_size, align_mask);
109	if (offset == -1) {
110		need_flush = true;
111		offset = iommu_area_alloc(iommu_gart_bitmap, iommu_pages, 0,
112					  size, base_index, boundary_size,
113					  align_mask);
114	}
115	if (offset != -1) {
116		next_bit = offset+size;
117		if (next_bit >= iommu_pages) {
118			next_bit = 0;
119			need_flush = true;
120		}
121	}
122	if (iommu_fullflush)
123		need_flush = true;
124	spin_unlock_irqrestore(&iommu_bitmap_lock, flags);
125
126	return offset;
127}
128
129static void free_iommu(unsigned long offset, int size)
130{
131	unsigned long flags;
132
133	spin_lock_irqsave(&iommu_bitmap_lock, flags);
134	bitmap_clear(iommu_gart_bitmap, offset, size);
135	if (offset >= next_bit)
136		next_bit = offset + size;
137	spin_unlock_irqrestore(&iommu_bitmap_lock, flags);
138}
139
140/*
141 * Use global flush state to avoid races with multiple flushers.
142 */
143static void flush_gart(void)
144{
145	unsigned long flags;
146
147	spin_lock_irqsave(&iommu_bitmap_lock, flags);
148	if (need_flush) {
149		amd_flush_garts();
150		need_flush = false;
151	}
152	spin_unlock_irqrestore(&iommu_bitmap_lock, flags);
153}
154
155#ifdef CONFIG_IOMMU_LEAK
156/* Debugging aid for drivers that don't free their IOMMU tables */
157static int leak_trace;
158static int iommu_leak_pages = 20;
159
160static void dump_leak(void)
161{
162	static int dump;
163
164	if (dump)
165		return;
166	dump = 1;
167
168	show_stack(NULL, NULL);
169	debug_dma_dump_mappings(NULL);
170}
171#endif
172
173static void iommu_full(struct device *dev, size_t size, int dir)
174{
175	/*
176	 * Ran out of IOMMU space for this operation. This is very bad.
177	 * Unfortunately the drivers cannot handle this operation properly.
178	 * Return some non mapped prereserved space in the aperture and
179	 * let the Northbridge deal with it. This will result in garbage
180	 * in the IO operation. When the size exceeds the prereserved space
181	 * memory corruption will occur or random memory will be DMAed
182	 * out. Hopefully no network devices use single mappings that big.
183	 */
184
185	dev_err(dev, "PCI-DMA: Out of IOMMU space for %lu bytes\n", size);
186
187	if (size > PAGE_SIZE*EMERGENCY_PAGES) {
188		if (dir == PCI_DMA_FROMDEVICE || dir == PCI_DMA_BIDIRECTIONAL)
189			panic("PCI-DMA: Memory would be corrupted\n");
190		if (dir == PCI_DMA_TODEVICE || dir == PCI_DMA_BIDIRECTIONAL)
191			panic(KERN_ERR
192				"PCI-DMA: Random memory would be DMAed\n");
193	}
194#ifdef CONFIG_IOMMU_LEAK
195	dump_leak();
196#endif
197}
198
199static inline int
200need_iommu(struct device *dev, unsigned long addr, size_t size)
201{
202	return force_iommu || !dma_capable(dev, addr, size);
203}
204
205static inline int
206nonforced_iommu(struct device *dev, unsigned long addr, size_t size)
207{
208	return !dma_capable(dev, addr, size);
209}
210
211/* Map a single continuous physical area into the IOMMU.
212 * Caller needs to check if the iommu is needed and flush.
213 */
214static dma_addr_t dma_map_area(struct device *dev, dma_addr_t phys_mem,
215				size_t size, int dir, unsigned long align_mask)
216{
217	unsigned long npages = iommu_num_pages(phys_mem, size, PAGE_SIZE);
218	unsigned long iommu_page;
219	int i;
220
221	if (unlikely(phys_mem + size > GART_MAX_PHYS_ADDR))
222		return bad_dma_addr;
223
224	iommu_page = alloc_iommu(dev, npages, align_mask);
225	if (iommu_page == -1) {
226		if (!nonforced_iommu(dev, phys_mem, size))
227			return phys_mem;
228		if (panic_on_overflow)
229			panic("dma_map_area overflow %lu bytes\n", size);
230		iommu_full(dev, size, dir);
231		return bad_dma_addr;
232	}
233
234	for (i = 0; i < npages; i++) {
235		iommu_gatt_base[iommu_page + i] = GPTE_ENCODE(phys_mem);
236		phys_mem += PAGE_SIZE;
237	}
238	return iommu_bus_base + iommu_page*PAGE_SIZE + (phys_mem & ~PAGE_MASK);
239}
240
241/* Map a single area into the IOMMU */
242static dma_addr_t gart_map_page(struct device *dev, struct page *page,
243				unsigned long offset, size_t size,
244				enum dma_data_direction dir,
245				struct dma_attrs *attrs)
246{
247	unsigned long bus;
248	phys_addr_t paddr = page_to_phys(page) + offset;
249
250	if (!dev)
251		dev = &x86_dma_fallback_dev;
252
253	if (!need_iommu(dev, paddr, size))
254		return paddr;
255
256	bus = dma_map_area(dev, paddr, size, dir, 0);
257	flush_gart();
258
259	return bus;
260}
261
262/*
263 * Free a DMA mapping.
264 */
265static void gart_unmap_page(struct device *dev, dma_addr_t dma_addr,
266			    size_t size, enum dma_data_direction dir,
267			    struct dma_attrs *attrs)
268{
269	unsigned long iommu_page;
270	int npages;
271	int i;
272
273	if (dma_addr < iommu_bus_base + EMERGENCY_PAGES*PAGE_SIZE ||
274	    dma_addr >= iommu_bus_base + iommu_size)
275		return;
276
277	iommu_page = (dma_addr - iommu_bus_base)>>PAGE_SHIFT;
278	npages = iommu_num_pages(dma_addr, size, PAGE_SIZE);
279	for (i = 0; i < npages; i++) {
280		iommu_gatt_base[iommu_page + i] = gart_unmapped_entry;
281	}
282	free_iommu(iommu_page, npages);
283}
284
285/*
286 * Wrapper for pci_unmap_single working with scatterlists.
287 */
288static void gart_unmap_sg(struct device *dev, struct scatterlist *sg, int nents,
289			  enum dma_data_direction dir, struct dma_attrs *attrs)
290{
291	struct scatterlist *s;
292	int i;
293
294	for_each_sg(sg, s, nents, i) {
295		if (!s->dma_length || !s->length)
296			break;
297		gart_unmap_page(dev, s->dma_address, s->dma_length, dir, NULL);
298	}
299}
300
301/* Fallback for dma_map_sg in case of overflow */
302static int dma_map_sg_nonforce(struct device *dev, struct scatterlist *sg,
303			       int nents, int dir)
304{
305	struct scatterlist *s;
306	int i;
307
308#ifdef CONFIG_IOMMU_DEBUG
309	pr_debug("dma_map_sg overflow\n");
310#endif
311
312	for_each_sg(sg, s, nents, i) {
313		unsigned long addr = sg_phys(s);
314
315		if (nonforced_iommu(dev, addr, s->length)) {
316			addr = dma_map_area(dev, addr, s->length, dir, 0);
317			if (addr == bad_dma_addr) {
318				if (i > 0)
319					gart_unmap_sg(dev, sg, i, dir, NULL);
320				nents = 0;
321				sg[0].dma_length = 0;
322				break;
323			}
324		}
325		s->dma_address = addr;
326		s->dma_length = s->length;
327	}
328	flush_gart();
329
330	return nents;
331}
332
333/* Map multiple scatterlist entries continuous into the first. */
334static int __dma_map_cont(struct device *dev, struct scatterlist *start,
335			  int nelems, struct scatterlist *sout,
336			  unsigned long pages)
337{
338	unsigned long iommu_start = alloc_iommu(dev, pages, 0);
339	unsigned long iommu_page = iommu_start;
340	struct scatterlist *s;
341	int i;
342
343	if (iommu_start == -1)
344		return -1;
345
346	for_each_sg(start, s, nelems, i) {
347		unsigned long pages, addr;
348		unsigned long phys_addr = s->dma_address;
349
350		BUG_ON(s != start && s->offset);
351		if (s == start) {
352			sout->dma_address = iommu_bus_base;
353			sout->dma_address += iommu_page*PAGE_SIZE + s->offset;
354			sout->dma_length = s->length;
355		} else {
356			sout->dma_length += s->length;
357		}
358
359		addr = phys_addr;
360		pages = iommu_num_pages(s->offset, s->length, PAGE_SIZE);
361		while (pages--) {
362			iommu_gatt_base[iommu_page] = GPTE_ENCODE(addr);
363			addr += PAGE_SIZE;
364			iommu_page++;
365		}
366	}
367	BUG_ON(iommu_page - iommu_start != pages);
368
369	return 0;
370}
371
372static inline int
373dma_map_cont(struct device *dev, struct scatterlist *start, int nelems,
374	     struct scatterlist *sout, unsigned long pages, int need)
375{
376	if (!need) {
377		BUG_ON(nelems != 1);
378		sout->dma_address = start->dma_address;
379		sout->dma_length = start->length;
380		return 0;
381	}
382	return __dma_map_cont(dev, start, nelems, sout, pages);
383}
384
385/*
386 * DMA map all entries in a scatterlist.
387 * Merge chunks that have page aligned sizes into a continuous mapping.
388 */
389static int gart_map_sg(struct device *dev, struct scatterlist *sg, int nents,
390		       enum dma_data_direction dir, struct dma_attrs *attrs)
391{
392	struct scatterlist *s, *ps, *start_sg, *sgmap;
393	int need = 0, nextneed, i, out, start;
394	unsigned long pages = 0;
395	unsigned int seg_size;
396	unsigned int max_seg_size;
397
398	if (nents == 0)
399		return 0;
400
401	if (!dev)
402		dev = &x86_dma_fallback_dev;
403
404	out		= 0;
405	start		= 0;
406	start_sg	= sg;
407	sgmap		= sg;
408	seg_size	= 0;
409	max_seg_size	= dma_get_max_seg_size(dev);
410	ps		= NULL; /* shut up gcc */
411
412	for_each_sg(sg, s, nents, i) {
413		dma_addr_t addr = sg_phys(s);
414
415		s->dma_address = addr;
416		BUG_ON(s->length == 0);
417
418		nextneed = need_iommu(dev, addr, s->length);
419
420		/* Handle the previous not yet processed entries */
421		if (i > start) {
422			/*
423			 * Can only merge when the last chunk ends on a
424			 * page boundary and the new one doesn't have an
425			 * offset.
426			 */
427			if (!iommu_merge || !nextneed || !need || s->offset ||
428			    (s->length + seg_size > max_seg_size) ||
429			    (ps->offset + ps->length) % PAGE_SIZE) {
430				if (dma_map_cont(dev, start_sg, i - start,
431						 sgmap, pages, need) < 0)
432					goto error;
433				out++;
434
435				seg_size	= 0;
436				sgmap		= sg_next(sgmap);
437				pages		= 0;
438				start		= i;
439				start_sg	= s;
440			}
441		}
442
443		seg_size += s->length;
444		need = nextneed;
445		pages += iommu_num_pages(s->offset, s->length, PAGE_SIZE);
446		ps = s;
447	}
448	if (dma_map_cont(dev, start_sg, i - start, sgmap, pages, need) < 0)
449		goto error;
450	out++;
451	flush_gart();
452	if (out < nents) {
453		sgmap = sg_next(sgmap);
454		sgmap->dma_length = 0;
455	}
456	return out;
457
458error:
459	flush_gart();
460	gart_unmap_sg(dev, sg, out, dir, NULL);
461
462	/* When it was forced or merged try again in a dumb way */
463	if (force_iommu || iommu_merge) {
464		out = dma_map_sg_nonforce(dev, sg, nents, dir);
465		if (out > 0)
466			return out;
467	}
468	if (panic_on_overflow)
469		panic("dma_map_sg: overflow on %lu pages\n", pages);
470
471	iommu_full(dev, pages << PAGE_SHIFT, dir);
472	for_each_sg(sg, s, nents, i)
473		s->dma_address = bad_dma_addr;
474	return 0;
475}
476
477/* allocate and map a coherent mapping */
478static void *
479gart_alloc_coherent(struct device *dev, size_t size, dma_addr_t *dma_addr,
480		    gfp_t flag)
481{
482	dma_addr_t paddr;
483	unsigned long align_mask;
484	struct page *page;
485
486	if (force_iommu && !(flag & GFP_DMA)) {
487		flag &= ~(__GFP_DMA | __GFP_HIGHMEM | __GFP_DMA32);
488		page = alloc_pages(flag | __GFP_ZERO, get_order(size));
489		if (!page)
490			return NULL;
491
492		align_mask = (1UL << get_order(size)) - 1;
493		paddr = dma_map_area(dev, page_to_phys(page), size,
494				     DMA_BIDIRECTIONAL, align_mask);
495
496		flush_gart();
497		if (paddr != bad_dma_addr) {
498			*dma_addr = paddr;
499			return page_address(page);
500		}
501		__free_pages(page, get_order(size));
502	} else
503		return dma_generic_alloc_coherent(dev, size, dma_addr, flag);
 
504
505	return NULL;
506}
507
508/* free a coherent mapping */
509static void
510gart_free_coherent(struct device *dev, size_t size, void *vaddr,
511		   dma_addr_t dma_addr)
512{
513	gart_unmap_page(dev, dma_addr, size, DMA_BIDIRECTIONAL, NULL);
514	free_pages((unsigned long)vaddr, get_order(size));
515}
516
517static int gart_mapping_error(struct device *dev, dma_addr_t dma_addr)
518{
519	return (dma_addr == bad_dma_addr);
520}
521
522static int no_agp;
523
524static __init unsigned long check_iommu_size(unsigned long aper, u64 aper_size)
525{
526	unsigned long a;
527
528	if (!iommu_size) {
529		iommu_size = aper_size;
530		if (!no_agp)
531			iommu_size /= 2;
532	}
533
534	a = aper + iommu_size;
535	iommu_size -= round_up(a, PMD_PAGE_SIZE) - a;
536
537	if (iommu_size < 64*1024*1024) {
538		pr_warning(
539			"PCI-DMA: Warning: Small IOMMU %luMB."
540			" Consider increasing the AGP aperture in BIOS\n",
541				iommu_size >> 20);
542	}
543
544	return iommu_size;
545}
546
547static __init unsigned read_aperture(struct pci_dev *dev, u32 *size)
548{
549	unsigned aper_size = 0, aper_base_32, aper_order;
550	u64 aper_base;
551
552	pci_read_config_dword(dev, AMD64_GARTAPERTUREBASE, &aper_base_32);
553	pci_read_config_dword(dev, AMD64_GARTAPERTURECTL, &aper_order);
554	aper_order = (aper_order >> 1) & 7;
555
556	aper_base = aper_base_32 & 0x7fff;
557	aper_base <<= 25;
558
559	aper_size = (32 * 1024 * 1024) << aper_order;
560	if (aper_base + aper_size > 0x100000000UL || !aper_size)
561		aper_base = 0;
562
563	*size = aper_size;
564	return aper_base;
565}
566
567static void enable_gart_translations(void)
568{
569	int i;
570
571	if (!amd_nb_has_feature(AMD_NB_GART))
572		return;
573
574	for (i = 0; i < amd_nb_num(); i++) {
575		struct pci_dev *dev = node_to_amd_nb(i)->misc;
576
577		enable_gart_translation(dev, __pa(agp_gatt_table));
578	}
579
580	/* Flush the GART-TLB to remove stale entries */
581	amd_flush_garts();
582}
583
584/*
585 * If fix_up_north_bridges is set, the north bridges have to be fixed up on
586 * resume in the same way as they are handled in gart_iommu_hole_init().
587 */
588static bool fix_up_north_bridges;
589static u32 aperture_order;
590static u32 aperture_alloc;
591
592void set_up_gart_resume(u32 aper_order, u32 aper_alloc)
593{
594	fix_up_north_bridges = true;
595	aperture_order = aper_order;
596	aperture_alloc = aper_alloc;
597}
598
599static void gart_fixup_northbridges(void)
600{
601	int i;
602
603	if (!fix_up_north_bridges)
604		return;
605
606	if (!amd_nb_has_feature(AMD_NB_GART))
607		return;
608
609	pr_info("PCI-DMA: Restoring GART aperture settings\n");
610
611	for (i = 0; i < amd_nb_num(); i++) {
612		struct pci_dev *dev = node_to_amd_nb(i)->misc;
613
614		/*
615		 * Don't enable translations just yet.  That is the next
616		 * step.  Restore the pre-suspend aperture settings.
617		 */
618		gart_set_size_and_enable(dev, aperture_order);
619		pci_write_config_dword(dev, AMD64_GARTAPERTUREBASE, aperture_alloc >> 25);
620	}
621}
622
623static void gart_resume(void)
624{
625	pr_info("PCI-DMA: Resuming GART IOMMU\n");
626
627	gart_fixup_northbridges();
628
629	enable_gart_translations();
630}
631
632static struct syscore_ops gart_syscore_ops = {
633	.resume		= gart_resume,
634
635};
636
637/*
638 * Private Northbridge GATT initialization in case we cannot use the
639 * AGP driver for some reason.
640 */
641static __init int init_amd_gatt(struct agp_kern_info *info)
642{
643	unsigned aper_size, gatt_size, new_aper_size;
644	unsigned aper_base, new_aper_base;
645	struct pci_dev *dev;
646	void *gatt;
647	int i;
648
649	pr_info("PCI-DMA: Disabling AGP.\n");
650
651	aper_size = aper_base = info->aper_size = 0;
652	dev = NULL;
653	for (i = 0; i < amd_nb_num(); i++) {
654		dev = node_to_amd_nb(i)->misc;
655		new_aper_base = read_aperture(dev, &new_aper_size);
656		if (!new_aper_base)
657			goto nommu;
658
659		if (!aper_base) {
660			aper_size = new_aper_size;
661			aper_base = new_aper_base;
662		}
663		if (aper_size != new_aper_size || aper_base != new_aper_base)
664			goto nommu;
665	}
666	if (!aper_base)
667		goto nommu;
668
669	info->aper_base = aper_base;
670	info->aper_size = aper_size >> 20;
671
672	gatt_size = (aper_size >> PAGE_SHIFT) * sizeof(u32);
673	gatt = (void *)__get_free_pages(GFP_KERNEL | __GFP_ZERO,
674					get_order(gatt_size));
675	if (!gatt)
676		panic("Cannot allocate GATT table");
677	if (set_memory_uc((unsigned long)gatt, gatt_size >> PAGE_SHIFT))
678		panic("Could not set GART PTEs to uncacheable pages");
679
680	agp_gatt_table = gatt;
681
682	register_syscore_ops(&gart_syscore_ops);
683
684	flush_gart();
685
686	pr_info("PCI-DMA: aperture base @ %x size %u KB\n",
687	       aper_base, aper_size>>10);
688
689	return 0;
690
691 nommu:
692	/* Should not happen anymore */
693	pr_warning("PCI-DMA: More than 4GB of RAM and no IOMMU\n"
694	       "falling back to iommu=soft.\n");
695	return -1;
696}
697
698static struct dma_map_ops gart_dma_ops = {
699	.map_sg				= gart_map_sg,
700	.unmap_sg			= gart_unmap_sg,
701	.map_page			= gart_map_page,
702	.unmap_page			= gart_unmap_page,
703	.alloc_coherent			= gart_alloc_coherent,
704	.free_coherent			= gart_free_coherent,
705	.mapping_error			= gart_mapping_error,
706};
707
708static void gart_iommu_shutdown(void)
709{
710	struct pci_dev *dev;
711	int i;
712
713	/* don't shutdown it if there is AGP installed */
714	if (!no_agp)
715		return;
716
717	if (!amd_nb_has_feature(AMD_NB_GART))
718		return;
719
720	for (i = 0; i < amd_nb_num(); i++) {
721		u32 ctl;
722
723		dev = node_to_amd_nb(i)->misc;
724		pci_read_config_dword(dev, AMD64_GARTAPERTURECTL, &ctl);
725
726		ctl &= ~GARTEN;
727
728		pci_write_config_dword(dev, AMD64_GARTAPERTURECTL, ctl);
729	}
730}
731
732int __init gart_iommu_init(void)
733{
734	struct agp_kern_info info;
735	unsigned long iommu_start;
736	unsigned long aper_base, aper_size;
737	unsigned long start_pfn, end_pfn;
738	unsigned long scratch;
739	long i;
740
741	if (!amd_nb_has_feature(AMD_NB_GART))
742		return 0;
743
744#ifndef CONFIG_AGP_AMD64
745	no_agp = 1;
746#else
747	/* Makefile puts PCI initialization via subsys_initcall first. */
748	/* Add other AMD AGP bridge drivers here */
749	no_agp = no_agp ||
750		(agp_amd64_init() < 0) ||
751		(agp_copy_info(agp_bridge, &info) < 0);
752#endif
753
754	if (no_iommu ||
755	    (!force_iommu && max_pfn <= MAX_DMA32_PFN) ||
756	    !gart_iommu_aperture ||
757	    (no_agp && init_amd_gatt(&info) < 0)) {
758		if (max_pfn > MAX_DMA32_PFN) {
759			pr_warning("More than 4GB of memory but GART IOMMU not available.\n");
760			pr_warning("falling back to iommu=soft.\n");
761		}
762		return 0;
763	}
764
765	/* need to map that range */
766	aper_size	= info.aper_size << 20;
767	aper_base	= info.aper_base;
768	end_pfn		= (aper_base>>PAGE_SHIFT) + (aper_size>>PAGE_SHIFT);
769
770	if (end_pfn > max_low_pfn_mapped) {
771		start_pfn = (aper_base>>PAGE_SHIFT);
772		init_memory_mapping(start_pfn<<PAGE_SHIFT, end_pfn<<PAGE_SHIFT);
773	}
774
775	pr_info("PCI-DMA: using GART IOMMU.\n");
776	iommu_size = check_iommu_size(info.aper_base, aper_size);
777	iommu_pages = iommu_size >> PAGE_SHIFT;
778
779	iommu_gart_bitmap = (void *) __get_free_pages(GFP_KERNEL | __GFP_ZERO,
780						      get_order(iommu_pages/8));
781	if (!iommu_gart_bitmap)
782		panic("Cannot allocate iommu bitmap\n");
783
784#ifdef CONFIG_IOMMU_LEAK
785	if (leak_trace) {
786		int ret;
787
788		ret = dma_debug_resize_entries(iommu_pages);
789		if (ret)
790			pr_debug("PCI-DMA: Cannot trace all the entries\n");
791	}
792#endif
793
794	/*
795	 * Out of IOMMU space handling.
796	 * Reserve some invalid pages at the beginning of the GART.
797	 */
798	bitmap_set(iommu_gart_bitmap, 0, EMERGENCY_PAGES);
799
800	pr_info("PCI-DMA: Reserving %luMB of IOMMU area in the AGP aperture\n",
801	       iommu_size >> 20);
802
803	agp_memory_reserved	= iommu_size;
804	iommu_start		= aper_size - iommu_size;
805	iommu_bus_base		= info.aper_base + iommu_start;
806	bad_dma_addr		= iommu_bus_base;
807	iommu_gatt_base		= agp_gatt_table + (iommu_start>>PAGE_SHIFT);
808
809	/*
810	 * Unmap the IOMMU part of the GART. The alias of the page is
811	 * always mapped with cache enabled and there is no full cache
812	 * coherency across the GART remapping. The unmapping avoids
813	 * automatic prefetches from the CPU allocating cache lines in
814	 * there. All CPU accesses are done via the direct mapping to
815	 * the backing memory. The GART address is only used by PCI
816	 * devices.
817	 */
818	set_memory_np((unsigned long)__va(iommu_bus_base),
819				iommu_size >> PAGE_SHIFT);
820	/*
821	 * Tricky. The GART table remaps the physical memory range,
822	 * so the CPU wont notice potential aliases and if the memory
823	 * is remapped to UC later on, we might surprise the PCI devices
824	 * with a stray writeout of a cacheline. So play it sure and
825	 * do an explicit, full-scale wbinvd() _after_ having marked all
826	 * the pages as Not-Present:
827	 */
828	wbinvd();
829
830	/*
831	 * Now all caches are flushed and we can safely enable
832	 * GART hardware.  Doing it early leaves the possibility
833	 * of stale cache entries that can lead to GART PTE
834	 * errors.
835	 */
836	enable_gart_translations();
837
838	/*
839	 * Try to workaround a bug (thanks to BenH):
840	 * Set unmapped entries to a scratch page instead of 0.
841	 * Any prefetches that hit unmapped entries won't get an bus abort
842	 * then. (P2P bridge may be prefetching on DMA reads).
843	 */
844	scratch = get_zeroed_page(GFP_KERNEL);
845	if (!scratch)
846		panic("Cannot allocate iommu scratch page");
847	gart_unmapped_entry = GPTE_ENCODE(__pa(scratch));
848	for (i = EMERGENCY_PAGES; i < iommu_pages; i++)
849		iommu_gatt_base[i] = gart_unmapped_entry;
850
851	flush_gart();
852	dma_ops = &gart_dma_ops;
853	x86_platform.iommu_shutdown = gart_iommu_shutdown;
854	swiotlb = 0;
855
856	return 0;
857}
858
859void __init gart_parse_options(char *p)
860{
861	int arg;
862
863#ifdef CONFIG_IOMMU_LEAK
864	if (!strncmp(p, "leak", 4)) {
865		leak_trace = 1;
866		p += 4;
867		if (*p == '=')
868			++p;
869		if (isdigit(*p) && get_option(&p, &arg))
870			iommu_leak_pages = arg;
871	}
872#endif
873	if (isdigit(*p) && get_option(&p, &arg))
874		iommu_size = arg;
875	if (!strncmp(p, "fullflush", 9))
876		iommu_fullflush = 1;
877	if (!strncmp(p, "nofullflush", 11))
878		iommu_fullflush = 0;
879	if (!strncmp(p, "noagp", 5))
880		no_agp = 1;
881	if (!strncmp(p, "noaperture", 10))
882		fix_aperture = 0;
883	/* duplicated from pci-dma.c */
884	if (!strncmp(p, "force", 5))
885		gart_iommu_aperture_allowed = 1;
886	if (!strncmp(p, "allowed", 7))
887		gart_iommu_aperture_allowed = 1;
888	if (!strncmp(p, "memaper", 7)) {
889		fallback_aper_force = 1;
890		p += 7;
891		if (*p == '=') {
892			++p;
893			if (get_option(&p, &arg))
894				fallback_aper_order = arg;
895		}
896	}
897}
898IOMMU_INIT_POST(gart_iommu_hole_init);