bus_machdep.c revision 93070
1/*-
2 * Copyright (c) 1996, 1997, 1998 The NetBSD Foundation, Inc.
3 * All rights reserved.
4 *
5 * This code is derived from software contributed to The NetBSD Foundation
6 * by Jason R. Thorpe of the Numerical Aerospace Simulation Facility,
7 * NASA Ames Research Center.
8 *
9 * Redistribution and use in source and binary forms, with or without
10 * modification, are permitted provided that the following conditions
11 * are met:
12 * 1. Redistributions of source code must retain the above copyright
13 *    notice, this list of conditions and the following disclaimer.
14 * 2. Redistributions in binary form must reproduce the above copyright
15 *    notice, this list of conditions and the following disclaimer in the
16 *    documentation and/or other materials provided with the distribution.
17 * 3. All advertising materials mentioning features or use of this software
18 *    must display the following acknowledgement:
19 *	This product includes software developed by the NetBSD
20 *	Foundation, Inc. and its contributors.
21 * 4. Neither the name of The NetBSD Foundation nor the names of its
22 *    contributors may be used to endorse or promote products derived
23 *    from this software without specific prior written permission.
24 *
25 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
26 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
27 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
28 * PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
29 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
30 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
31 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
32 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
33 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
34 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
35 * POSSIBILITY OF SUCH DAMAGE.
36 */
37/*
38 * Copyright (c) 1992, 1993
39 *	The Regents of the University of California.  All rights reserved.
40 *
41 * This software was developed by the Computer Systems Engineering group
42 * at Lawrence Berkeley Laboratory under DARPA contract BG 91-66 and
43 * contributed to Berkeley.
44 *
45 * All advertising materials mentioning features or use of this software
46 * must display the following acknowledgement:
47 *	This product includes software developed by the University of
48 *	California, Lawrence Berkeley Laboratory.
49 *
50 * Redistribution and use in source and binary forms, with or without
51 * modification, are permitted provided that the following conditions
52 * are met:
53 * 1. Redistributions of source code must retain the above copyright
54 *    notice, this list of conditions and the following disclaimer.
55 * 2. Redistributions in binary form must reproduce the above copyright
56 *    notice, this list of conditions and the following disclaimer in the
57 *    documentation and/or other materials provided with the distribution.
58 * 3. All advertising materials mentioning features or use of this software
59 *    must display the following acknowledgement:
60 *	This product includes software developed by the University of
61 *	California, Berkeley and its contributors.
62 * 4. Neither the name of the University nor the names of its contributors
63 *    may be used to endorse or promote products derived from this software
64 *    without specific prior written permission.
65 *
66 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
67 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
68 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
69 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
70 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
71 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
72 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
73 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
74 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
75 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
76 * SUCH DAMAGE.
77 */
78/*
79 * Copyright (c) 1997, 1998 Justin T. Gibbs.
80 * All rights reserved.
81 * Copyright 2001 by Thomas Moestl <tmm@FreeBSD.org>.  All rights reserved.
82 *
83 * Redistribution and use in source and binary forms, with or without
84 * modification, are permitted provided that the following conditions
85 * are met:
86 * 1. Redistributions of source code must retain the above copyright
87 *    notice, this list of conditions, and the following disclaimer,
88 *    without modification, immediately at the beginning of the file.
89 * 2. The name of the author may not be used to endorse or promote products
90 *    derived from this software without specific prior written permission.
91 *
92 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
93 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
94 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
95 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE FOR
96 * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
97 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
98 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
99 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
100 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
101 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
102 * SUCH DAMAGE.
103 *
104 *	from: @(#)machdep.c	8.6 (Berkeley) 1/14/94
105 *	from: NetBSD: machdep.c,v 1.111 2001/09/15 07:13:40 eeh Exp
106 *	and
107 * 	from: FreeBSD: src/sys/i386/i386/busdma_machdep.c,v 1.24 2001/08/15
108 *
109 * $FreeBSD: head/sys/sparc64/sparc64/bus_machdep.c 93070 2002-03-24 02:50:53Z tmm $
110 */
111
112#include <sys/param.h>
113#include <sys/bus.h>
114#include <sys/malloc.h>
115#include <sys/proc.h>
116#include <sys/smp.h>
117#include <sys/systm.h>
118
119#include <vm/vm.h>
120#include <vm/vm_extern.h>
121#include <vm/vm_kern.h>
122#include <vm/vm_page.h>
123#include <vm/vm_param.h>
124
125#include <machine/asi.h>
126#include <machine/bus.h>
127#include <machine/bus_private.h>
128#include <machine/cache.h>
129#include <machine/pmap.h>
130#include <machine/smp.h>
131#include <machine/tlb.h>
132
133/* ASI's for bus access. */
134int bus_type_asi[] = {
135	ASI_PHYS_BYPASS_EC_WITH_EBIT,		/* UPA */
136	ASI_PHYS_BYPASS_EC_WITH_EBIT,		/* SBUS */
137	ASI_PHYS_BYPASS_EC_WITH_EBIT_L,		/* PCI configuration space */
138	ASI_PHYS_BYPASS_EC_WITH_EBIT_L,		/* PCI memory space */
139	ASI_PHYS_BYPASS_EC_WITH_EBIT_L,		/* PCI I/O space */
140	0
141};
142
143int bus_stream_asi[] = {
144	ASI_PHYS_BYPASS_EC_WITH_EBIT,		/* UPA */
145	ASI_PHYS_BYPASS_EC_WITH_EBIT,		/* SBUS */
146	ASI_PHYS_BYPASS_EC_WITH_EBIT,		/* PCI configuration space */
147	ASI_PHYS_BYPASS_EC_WITH_EBIT,		/* PCI memory space */
148	ASI_PHYS_BYPASS_EC_WITH_EBIT,		/* PCI I/O space */
149	0
150};
151
152/*
153 * busdma support code.
154 * Note: there is no support for bounce buffers yet.
155 */
156
157static int nexus_dmamap_create(bus_dma_tag_t, bus_dma_tag_t, int,
158    bus_dmamap_t *);
159static int nexus_dmamap_destroy(bus_dma_tag_t, bus_dma_tag_t, bus_dmamap_t);
160static int nexus_dmamap_load(bus_dma_tag_t, bus_dma_tag_t, bus_dmamap_t,
161    void *, bus_size_t, bus_dmamap_callback_t *, void *, int);
162static void nexus_dmamap_unload(bus_dma_tag_t, bus_dma_tag_t, bus_dmamap_t);
163static void nexus_dmamap_sync(bus_dma_tag_t, bus_dma_tag_t, bus_dmamap_t,
164    bus_dmasync_op_t);
165static int nexus_dmamem_alloc(bus_dma_tag_t, bus_dma_tag_t, void **, int,
166    bus_dmamap_t *);
167static void nexus_dmamem_free(bus_dma_tag_t, bus_dma_tag_t, void *,
168    bus_dmamap_t);
169
170/*
171 * Since there is now way for a device to obtain a dma tag from its parent
172 * we use this kluge to handle different the different supported bus systems.
173 * The sparc64_root_dma_tag is used as parent for tags that have none, so that
174 * the correct methods will be used.
175 */
176bus_dma_tag_t sparc64_root_dma_tag;
177
178/*
179 * Allocate a device specific dma_tag.
180 */
181int
182bus_dma_tag_create(bus_dma_tag_t parent, bus_size_t alignment,
183    bus_size_t boundary, bus_addr_t lowaddr, bus_addr_t highaddr,
184    bus_dma_filter_t *filter, void *filterarg, bus_size_t maxsize,
185    int nsegments, bus_size_t maxsegsz, int flags, bus_dma_tag_t *dmat)
186{
187
188	bus_dma_tag_t newtag;
189
190	/* Return a NULL tag on failure */
191	*dmat = NULL;
192
193	newtag = (bus_dma_tag_t)malloc(sizeof(*newtag), M_DEVBUF, M_NOWAIT);
194	if (newtag == NULL)
195		return (ENOMEM);
196
197	newtag->parent = parent != NULL ? parent : sparc64_root_dma_tag;
198	newtag->alignment = alignment;
199	newtag->boundary = boundary;
200	newtag->lowaddr = trunc_page((vm_offset_t)lowaddr) + (PAGE_SIZE - 1);
201	newtag->highaddr = trunc_page((vm_offset_t)highaddr) + (PAGE_SIZE - 1);
202	newtag->filter = filter;
203	newtag->filterarg = filterarg;
204	newtag->maxsize = maxsize;
205	newtag->nsegments = nsegments;
206	newtag->maxsegsz = maxsegsz;
207	newtag->flags = flags;
208	newtag->ref_count = 1; /* Count ourselves */
209	newtag->map_count = 0;
210
211	newtag->dmamap_create = NULL;
212	newtag->dmamap_destroy = NULL;
213	newtag->dmamap_load = NULL;
214	newtag->dmamap_unload = NULL;
215	newtag->dmamap_sync = NULL;
216	newtag->dmamem_alloc = NULL;
217	newtag->dmamem_free = NULL;
218
219	/* Take into account any restrictions imposed by our parent tag */
220	if (parent != NULL) {
221		newtag->lowaddr = ulmin(parent->lowaddr, newtag->lowaddr);
222		newtag->highaddr = ulmax(parent->highaddr, newtag->highaddr);
223		/*
224		 * XXX Not really correct??? Probably need to honor boundary
225		 *     all the way up the inheritence chain.
226		 */
227		newtag->boundary = ulmax(parent->boundary, newtag->boundary);
228	}
229	newtag->parent->ref_count++;
230
231	*dmat = newtag;
232	return (0);
233}
234
235int
236bus_dma_tag_destroy(bus_dma_tag_t dmat)
237{
238	bus_dma_tag_t parent;
239
240	if (dmat != NULL) {
241		if (dmat->map_count != 0)
242			return (EBUSY);
243		while (dmat != NULL) {
244			parent = dmat->parent;
245			dmat->ref_count--;
246			if (dmat->ref_count == 0) {
247				free(dmat, M_DEVBUF);
248				/*
249				 * Last reference count, so
250				 * release our reference
251				 * count on our parent.
252				 */
253				dmat = parent;
254			} else
255				dmat = NULL;
256		}
257	}
258	return (0);
259}
260
261/*
262 * Common function for DMA map creation.  May be called by bus-specific
263 * DMA map creation functions.
264 */
265static int
266nexus_dmamap_create(bus_dma_tag_t pdmat, bus_dma_tag_t ddmat, int flags,
267    bus_dmamap_t *mapp)
268{
269
270	/* Not much to do...? */
271	*mapp = malloc(sizeof(**mapp), M_DEVBUF, M_WAITOK | M_ZERO);
272	ddmat->map_count++;
273	return (0);
274}
275
276/*
277 * Common function for DMA map destruction.  May be called by bus-specific
278 * DMA map destruction functions.
279 */
280static int
281nexus_dmamap_destroy(bus_dma_tag_t pdmat, bus_dma_tag_t ddmat, bus_dmamap_t map)
282{
283
284	free(map, M_DEVBUF);
285	ddmat->map_count--;
286	return (0);
287}
288
289#define BUS_DMAMAP_NSEGS ((BUS_SPACE_MAXSIZE / PAGE_SIZE) + 1)
290
291/*
292 * Common function for loading a DMA map with a linear buffer.  May
293 * be called by bus-specific DMA map load functions.
294 *
295 * Most SPARCs have IOMMUs in the bus controllers.  In those cases
296 * they only need one segment and will use virtual addresses for DVMA.
297 * Those bus controllers should intercept these vectors and should
298 * *NEVER* call nexus_dmamap_load() which is used only by devices that
299 * bypass DVMA.
300 */
301static int
302nexus_dmamap_load(bus_dma_tag_t pdmat, bus_dma_tag_t ddmat, bus_dmamap_t map,
303    void *buf, bus_size_t buflen, bus_dmamap_callback_t *callback,
304    void *callback_arg, int flags)
305{
306	vm_offset_t vaddr;
307	vm_offset_t paddr;
308#ifdef __GNUC__
309	bus_dma_segment_t dm_segments[ddmat->nsegments];
310#else
311	bus_dma_segment_t dm_segments[BUS_DMAMAP_NSEGS];
312#endif
313	bus_dma_segment_t *sg;
314	int seg;
315	int error;
316	vm_offset_t nextpaddr;
317	bus_size_t size;
318
319	error = 0;
320
321	vaddr = (vm_offset_t)buf;
322	sg = &dm_segments[0];
323	seg = 1;
324	sg->ds_len = 0;
325
326	map->buf = buf;
327	map->buflen = buflen;
328	map->start = (bus_addr_t)buf;
329
330	nextpaddr = 0;
331	do {
332		paddr = pmap_kextract(vaddr);
333		size = PAGE_SIZE - (paddr & PAGE_MASK);
334		if (size > buflen)
335			size = buflen;
336
337		if (sg->ds_len == 0) {
338			sg->ds_addr = paddr;
339			sg->ds_len = size;
340		} else if (paddr == nextpaddr) {
341			sg->ds_len += size;
342		} else {
343			/* Go to the next segment */
344			sg++;
345			seg++;
346			if (seg > ddmat->nsegments)
347				break;
348			sg->ds_addr = paddr;
349			sg->ds_len = size;
350		}
351		vaddr += size;
352		nextpaddr = paddr + size;
353		buflen -= size;
354	} while (buflen > 0);
355
356	if (buflen != 0) {
357		printf("bus_dmamap_load: Too many segs! buf_len = 0x%lx\n",
358		       (u_long)buflen);
359		error = EFBIG;
360	}
361
362	(*callback)(callback_arg, dm_segments, seg, error);
363
364	return (0);
365}
366
367/*
368 * Common function for unloading a DMA map.  May be called by
369 * bus-specific DMA map unload functions.
370 */
371static void
372nexus_dmamap_unload(bus_dma_tag_t pdmat, bus_dma_tag_t ddmat, bus_dmamap_t map)
373{
374
375	/* Nothing to do...? */
376}
377
378/*
379 * Common function for DMA map synchronization.  May be called
380 * by bus-specific DMA map synchronization functions.
381 */
382static void
383nexus_dmamap_sync(bus_dma_tag_t pdmat, bus_dma_tag_t ddmat, bus_dmamap_t map,
384    bus_dmasync_op_t op)
385{
386
387	/*
388	 * We sync out our caches, but the bus must do the same.
389	 *
390	 * Actually a #Sync is expensive.  We should optimize.
391	 */
392	if ((op == BUS_DMASYNC_PREREAD) || (op == BUS_DMASYNC_PREWRITE)) {
393		/*
394		 * Don't really need to do anything, but flush any pending
395		 * writes anyway.
396		 */
397		membar(Sync);
398	}
399	if (op == BUS_DMASYNC_POSTREAD) {
400		/*
401		 * Invalidate the caches (it is unclear whether that is really
402		 * needed. The manual only mentions that PCI transactions are
403		 * cache coherent).
404		 */
405		ecache_flush((vm_offset_t)map->buf,
406		    (vm_offset_t)map->buf + map->buflen - 1);
407	}
408	if (op == BUS_DMASYNC_POSTWRITE) {
409		/* Nothing to do.  Handled by the bus controller. */
410	}
411}
412
413/*
414 * Helper functions for buses that use their private dmamem_alloc/dmamem_free
415 * versions.
416 * These differ from the dmamap_alloc() functions in that they create a tag
417 * that is specifically for use with dmamem_alloc'ed memory.
418 * These are primitive now, but I expect that some fields of the map will need
419 * to be filled soon.
420 */
421int
422sparc64_dmamem_alloc_map(bus_dma_tag_t dmat, bus_dmamap_t *mapp)
423{
424
425	*mapp = malloc(sizeof(**mapp), M_DEVBUF, M_WAITOK | M_ZERO);
426	if (*mapp == NULL)
427		return (ENOMEM);
428
429	dmat->map_count++;
430	return (0);
431}
432
433void
434sparc64_dmamem_free_map(bus_dma_tag_t dmat, bus_dmamap_t map)
435{
436
437	free(map, M_DEVBUF);
438	dmat->map_count--;
439}
440
441/*
442 * Common function for DMA-safe memory allocation.  May be called
443 * by bus-specific DMA memory allocation functions.
444 */
445static int
446nexus_dmamem_alloc(bus_dma_tag_t pdmat, bus_dma_tag_t ddmat, void **vaddr,
447    int flags, bus_dmamap_t *mapp)
448{
449
450	if ((ddmat->maxsize <= PAGE_SIZE)) {
451		*vaddr = malloc(ddmat->maxsize, M_DEVBUF,
452		    (flags & BUS_DMA_NOWAIT) ? M_NOWAIT : M_WAITOK);
453	} else {
454		/*
455		 * XXX: Use contigmalloc until it is merged into this facility
456		 * and handles multi-seg allocations.  Nobody is doing multi-seg
457		 * allocations yet though.
458		 */
459		*vaddr = contigmalloc(ddmat->maxsize, M_DEVBUF,
460		    (flags & BUS_DMA_NOWAIT) ? M_NOWAIT : M_WAITOK,
461		    0ul, ddmat->lowaddr,
462		    ddmat->alignment ? ddmat->alignment : 1UL,
463		    ddmat->boundary);
464	}
465	if (*vaddr == NULL) {
466		free(*mapp, M_DEVBUF);
467		return (ENOMEM);
468	}
469	return (0);
470}
471
472/*
473 * Common function for freeing DMA-safe memory.  May be called by
474 * bus-specific DMA memory free functions.
475 */
476static void
477nexus_dmamem_free(bus_dma_tag_t pdmat, bus_dma_tag_t ddmat, void *vaddr,
478    bus_dmamap_t map)
479{
480
481	sparc64_dmamem_free_map(ddmat, map);
482	if ((ddmat->maxsize <= PAGE_SIZE))
483		free(vaddr, M_DEVBUF);
484	else
485		contigfree(vaddr, ddmat->maxsize, M_DEVBUF);
486}
487
488struct bus_dma_tag nexus_dmatag = {
489	NULL,
490	NULL,
491	8,
492	0,
493	0,
494	0x3ffffffff,
495	NULL,		/* XXX */
496	NULL,
497	0x3ffffffff,	/* XXX */
498	0xff,		/* XXX */
499	0xffffffff,	/* XXX */
500	0,
501	0,
502	0,
503	nexus_dmamap_create,
504	nexus_dmamap_destroy,
505	nexus_dmamap_load,
506	nexus_dmamap_unload,
507	nexus_dmamap_sync,
508
509	nexus_dmamem_alloc,
510	nexus_dmamem_free,
511};
512
513/*
514 * Helpers to map/unmap bus memory
515 */
516int
517sparc64_bus_mem_map(bus_space_tag_t tag, bus_space_handle_t handle,
518    bus_size_t size, int flags, vm_offset_t vaddr, void **hp)
519{
520	vm_offset_t addr;
521	vm_offset_t sva;
522	vm_offset_t va;
523	vm_offset_t pa;
524	vm_size_t vsz;
525	u_long pm_flags;
526
527	addr = (vm_offset_t)handle;
528	size = round_page(size);
529	if (size == 0) {
530		printf("sparc64_bus_map: zero size\n");
531		return (EINVAL);
532	}
533	switch (tag->type) {
534	case PCI_CONFIG_BUS_SPACE:
535	case PCI_IO_BUS_SPACE:
536	case PCI_MEMORY_BUS_SPACE:
537		pm_flags = TD_IE;
538		break;
539	default:
540		pm_flags = 0;
541		break;
542	}
543
544	if (!(flags & BUS_SPACE_MAP_CACHEABLE))
545		pm_flags |= TD_E;
546
547	if (vaddr != NULL)
548		sva = trunc_page(vaddr);
549	else {
550		if ((sva = kmem_alloc_nofault(kernel_map, size)) == NULL)
551			panic("sparc64_bus_map: cannot allocate virtual "
552			    "memory");
553	}
554
555	/* note: preserve page offset */
556	*hp = (void *)(sva | ((u_long)addr & PAGE_MASK));
557
558	pa = trunc_page(addr);
559	if ((flags & BUS_SPACE_MAP_READONLY) == 0)
560		pm_flags |= TD_W;
561
562	va = sva;
563	vsz = size;
564	do {
565		pmap_kenter_flags(va, pa, pm_flags);
566		va += PAGE_SIZE;
567		pa += PAGE_SIZE;
568	} while ((vsz -= PAGE_SIZE) > 0);
569	tlb_range_demap(kernel_pmap, sva, sva + size - 1);
570	return (0);
571}
572
573int
574sparc64_bus_mem_unmap(void *bh, bus_size_t size)
575{
576	vm_offset_t sva;
577	vm_offset_t va;
578	vm_offset_t endva;
579
580	sva = trunc_page((vm_offset_t)bh);
581	endva = sva + round_page(size);
582	for (va = sva; va < endva; va += PAGE_SIZE)
583		pmap_kremove(va);
584	tlb_range_demap(kernel_pmap, sva, sva + size - 1);
585	kmem_free(kernel_map, sva, size);
586	return (0);
587}
588
589/*
590 * Fake up a bus tag, for use by console drivers in early boot when the regular
591 * means to allocate resources are not yet available.
592 * Note that these tags are not eligible for bus_space_barrier operations.
593 * Addr is the physical address of the desired start of the handle.
594 */
595bus_space_handle_t
596sparc64_fake_bustag(int space, bus_addr_t addr, struct bus_space_tag *ptag)
597{
598
599	ptag->cookie = NULL;
600	ptag->parent = NULL;
601	ptag->type = space;
602	ptag->bus_barrier = NULL;
603	return (addr);
604}
605
606/*
607 * Base bus space handlers.
608 */
609static void nexus_bus_barrier(bus_space_tag_t, bus_space_handle_t,
610    bus_size_t, bus_size_t, int);
611
612static void
613nexus_bus_barrier(bus_space_tag_t t, bus_space_handle_t h, bus_size_t offset,
614    bus_size_t size, int flags)
615{
616
617	/*
618	 * We have lots of alternatives depending on whether we're
619	 * synchronizing loads with loads, loads with stores, stores
620	 * with loads, or stores with stores.  The only ones that seem
621	 * generic are #Sync and #MemIssue.  I'll use #Sync for safety.
622	 */
623	switch(flags) {
624	case BUS_SPACE_BARRIER_READ | BUS_SPACE_BARRIER_WRITE:
625	case BUS_SPACE_BARRIER_READ:
626	case BUS_SPACE_BARRIER_WRITE:
627		membar(Sync);
628		break;
629	default:
630		panic("sparc64_bus_barrier: unknown flags");
631	}
632	return;
633}
634
635struct bus_space_tag nexus_bustag = {
636	NULL,				/* cookie */
637	NULL,				/* parent bus tag */
638	UPA_BUS_SPACE,			/* type */
639	nexus_bus_barrier,		/* bus_space_barrier */
640};
641