2 * Copyright (c) 1996, 1997, 1998 The NetBSD Foundation, Inc.
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.
9 * Redistribution and use in source and binary forms, with or without
10 * modification, are permitted provided that the following conditions
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.
18 * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
19 * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
20 * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
21 * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
22 * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
23 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
24 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
25 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
26 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
27 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
28 * POSSIBILITY OF SUCH DAMAGE.
31 * Copyright (c) 1992, 1993
32 * The Regents of the University of California. All rights reserved.
34 * This software was developed by the Computer Systems Engineering group
35 * at Lawrence Berkeley Laboratory under DARPA contract BG 91-66 and
36 * contributed to Berkeley.
38 * Redistribution and use in source and binary forms, with or without
39 * modification, are permitted provided that the following conditions
41 * 1. Redistributions of source code must retain the above copyright
42 * notice, this list of conditions and the following disclaimer.
43 * 2. Redistributions in binary form must reproduce the above copyright
44 * notice, this list of conditions and the following disclaimer in the
45 * documentation and/or other materials provided with the distribution.
46 * 4. Neither the name of the University nor the names of its contributors
47 * may be used to endorse or promote products derived from this software
48 * without specific prior written permission.
50 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
51 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
52 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
53 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
54 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
55 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
56 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
57 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
58 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
59 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
63 * Copyright (c) 1997, 1998 Justin T. Gibbs.
64 * All rights reserved.
65 * Copyright 2001 by Thomas Moestl <tmm@FreeBSD.org>. All rights reserved.
67 * Redistribution and use in source and binary forms, with or without
68 * modification, are permitted provided that the following conditions
70 * 1. Redistributions of source code must retain the above copyright
71 * notice, this list of conditions, and the following disclaimer,
72 * without modification, immediately at the beginning of the file.
73 * 2. The name of the author may not be used to endorse or promote products
74 * derived from this software without specific prior written permission.
76 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
77 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
78 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
79 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE FOR
80 * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
81 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
82 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
83 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
84 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
85 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
88 * from: @(#)machdep.c 8.6 (Berkeley) 1/14/94
89 * from: NetBSD: machdep.c,v 1.221 2008/04/28 20:23:37 martin Exp
91 * from: FreeBSD: src/sys/i386/i386/busdma_machdep.c,v 1.24 2001/08/15
94 #include <sys/cdefs.h>
95 __FBSDID("$FreeBSD$");
97 #include <sys/param.h>
100 #include <sys/malloc.h>
101 #include <sys/mbuf.h>
102 #include <sys/mutex.h>
103 #include <sys/proc.h>
105 #include <sys/systm.h>
109 #include <vm/vm_extern.h>
110 #include <vm/vm_kern.h>
111 #include <vm/vm_page.h>
112 #include <vm/vm_param.h>
113 #include <vm/vm_map.h>
115 #include <machine/asi.h>
116 #include <machine/atomic.h>
117 #include <machine/bus.h>
118 #include <machine/bus_private.h>
119 #include <machine/cache.h>
120 #include <machine/smp.h>
121 #include <machine/tlb.h>
123 static void nexus_bus_barrier(bus_space_tag_t, bus_space_handle_t,
124 bus_size_t, bus_size_t, int);
126 /* ASIs for bus access */
127 const int bus_type_asi[] = {
128 ASI_PHYS_BYPASS_EC_WITH_EBIT, /* nexus */
129 ASI_PHYS_BYPASS_EC_WITH_EBIT, /* SBus */
130 ASI_PHYS_BYPASS_EC_WITH_EBIT_L, /* PCI configuration space */
131 ASI_PHYS_BYPASS_EC_WITH_EBIT_L, /* PCI memory space */
132 ASI_PHYS_BYPASS_EC_WITH_EBIT_L, /* PCI I/O space */
136 const int bus_stream_asi[] = {
137 ASI_PHYS_BYPASS_EC_WITH_EBIT, /* nexus */
138 ASI_PHYS_BYPASS_EC_WITH_EBIT, /* SBus */
139 ASI_PHYS_BYPASS_EC_WITH_EBIT, /* PCI configuration space */
140 ASI_PHYS_BYPASS_EC_WITH_EBIT, /* PCI memory space */
141 ASI_PHYS_BYPASS_EC_WITH_EBIT, /* PCI I/O space */
146 * Convenience function for manipulating driver locks from busdma (during
147 * busdma_swi, for example). Drivers that don't provide their own locks
148 * should specify &Giant to dmat->lockfuncarg. Drivers that use their own
149 * non-mutex locking scheme don't have to use this at all.
152 busdma_lock_mutex(void *arg, bus_dma_lock_op_t op)
156 dmtx = (struct mtx *)arg;
165 panic("Unknown operation 0x%x for busdma_lock_mutex!", op);
170 * dflt_lock should never get called. It gets put into the dma tag when
171 * lockfunc == NULL, which is only valid if the maps that are associated
172 * with the tag are meant to never be defered.
173 * XXX Should have a way to identify which driver is responsible here.
176 dflt_lock(void *arg, bus_dma_lock_op_t op)
179 panic("driver error: busdma dflt_lock called");
183 * Allocate a device specific dma_tag.
186 bus_dma_tag_create(bus_dma_tag_t parent, bus_size_t alignment,
187 bus_size_t boundary, bus_addr_t lowaddr, bus_addr_t highaddr,
188 bus_dma_filter_t *filter, void *filterarg, bus_size_t maxsize,
189 int nsegments, bus_size_t maxsegsz, int flags, bus_dma_lock_t *lockfunc,
190 void *lockfuncarg, bus_dma_tag_t *dmat)
192 bus_dma_tag_t newtag;
194 /* Return a NULL tag on failure */
197 /* Enforce the usage of BUS_GET_DMA_TAG(). */
199 panic("%s: parent DMA tag NULL", __func__);
201 newtag = (bus_dma_tag_t)malloc(sizeof(*newtag), M_DEVBUF, M_NOWAIT);
206 * The method table pointer and the cookie need to be taken over from
209 newtag->dt_cookie = parent->dt_cookie;
210 newtag->dt_mt = parent->dt_mt;
212 newtag->dt_parent = parent;
213 newtag->dt_alignment = alignment;
214 newtag->dt_boundary = boundary;
215 newtag->dt_lowaddr = trunc_page((vm_offset_t)lowaddr) + (PAGE_SIZE - 1);
216 newtag->dt_highaddr = trunc_page((vm_offset_t)highaddr) +
218 newtag->dt_filter = filter;
219 newtag->dt_filterarg = filterarg;
220 newtag->dt_maxsize = maxsize;
221 newtag->dt_nsegments = nsegments;
222 newtag->dt_maxsegsz = maxsegsz;
223 newtag->dt_flags = flags;
224 newtag->dt_ref_count = 1; /* Count ourselves */
225 newtag->dt_map_count = 0;
227 if (lockfunc != NULL) {
228 newtag->dt_lockfunc = lockfunc;
229 newtag->dt_lockfuncarg = lockfuncarg;
231 newtag->dt_lockfunc = dflt_lock;
232 newtag->dt_lockfuncarg = NULL;
235 newtag->dt_segments = NULL;
237 /* Take into account any restrictions imposed by our parent tag. */
238 newtag->dt_lowaddr = ulmin(parent->dt_lowaddr, newtag->dt_lowaddr);
239 newtag->dt_highaddr = ulmax(parent->dt_highaddr, newtag->dt_highaddr);
240 if (newtag->dt_boundary == 0)
241 newtag->dt_boundary = parent->dt_boundary;
242 else if (parent->dt_boundary != 0)
243 newtag->dt_boundary = ulmin(parent->dt_boundary,
244 newtag->dt_boundary);
245 atomic_add_int(&parent->dt_ref_count, 1);
247 if (newtag->dt_boundary > 0)
248 newtag->dt_maxsegsz = ulmin(newtag->dt_maxsegsz,
249 newtag->dt_boundary);
256 bus_dma_tag_destroy(bus_dma_tag_t dmat)
258 bus_dma_tag_t parent;
261 if (dmat->dt_map_count != 0)
263 while (dmat != NULL) {
264 parent = dmat->dt_parent;
265 atomic_subtract_int(&dmat->dt_ref_count, 1);
266 if (dmat->dt_ref_count == 0) {
267 if (dmat->dt_segments != NULL)
268 free(dmat->dt_segments, M_DEVBUF);
269 free(dmat, M_DEVBUF);
271 * Last reference count, so
272 * release our reference
273 * count on our parent.
283 /* Allocate/free a tag, and do the necessary management work. */
285 sparc64_dma_alloc_map(bus_dma_tag_t dmat, bus_dmamap_t *mapp)
288 if (dmat->dt_segments == NULL) {
289 dmat->dt_segments = (bus_dma_segment_t *)malloc(
290 sizeof(bus_dma_segment_t) * dmat->dt_nsegments, M_DEVBUF,
292 if (dmat->dt_segments == NULL)
295 *mapp = malloc(sizeof(**mapp), M_DEVBUF, M_NOWAIT | M_ZERO);
299 SLIST_INIT(&(*mapp)->dm_reslist);
300 dmat->dt_map_count++;
305 sparc64_dma_free_map(bus_dma_tag_t dmat, bus_dmamap_t map)
309 dmat->dt_map_count--;
313 nexus_dmamap_create(bus_dma_tag_t dmat, int flags, bus_dmamap_t *mapp)
316 return (sparc64_dma_alloc_map(dmat, mapp));
320 nexus_dmamap_destroy(bus_dma_tag_t dmat, bus_dmamap_t map)
323 sparc64_dma_free_map(dmat, map);
328 * Utility function to load a linear buffer. lastaddrp holds state
329 * between invocations (for multiple-buffer loads). segp contains
330 * the starting segment on entrace, and the ending segment on exit.
331 * first indicates if this is the first invocation of this function.
334 _nexus_dmamap_load_buffer(bus_dma_tag_t dmat, void *buf, bus_size_t buflen,
335 struct thread *td, int flags, bus_addr_t *lastaddrp,
336 bus_dma_segment_t *segs, int *segp, int first)
339 bus_addr_t curaddr, lastaddr, baddr, bmask;
340 vm_offset_t vaddr = (vm_offset_t)buf;
345 pmap = vmspace_pmap(td->td_proc->p_vmspace);
349 lastaddr = *lastaddrp;
350 bmask = ~(dmat->dt_boundary - 1);
352 for (seg = *segp; buflen > 0 ; ) {
354 * Get the physical address for this segment.
357 curaddr = pmap_extract(pmap, vaddr);
359 curaddr = pmap_kextract(vaddr);
362 * Compute the segment size, and adjust counts.
364 sgsize = PAGE_SIZE - ((u_long)curaddr & PAGE_MASK);
365 if (sgsize > dmat->dt_maxsegsz)
366 sgsize = dmat->dt_maxsegsz;
371 * Make sure we don't cross any boundaries.
373 if (dmat->dt_boundary > 0) {
374 baddr = (curaddr + dmat->dt_boundary) & bmask;
375 if (sgsize > (baddr - curaddr))
376 sgsize = (baddr - curaddr);
380 * Insert chunk into a segment, coalescing with
381 * previous segment if possible.
384 segs[seg].ds_addr = curaddr;
385 segs[seg].ds_len = sgsize;
388 if (curaddr == lastaddr &&
389 (segs[seg].ds_len + sgsize) <= dmat->dt_maxsegsz &&
390 (dmat->dt_boundary == 0 ||
391 (segs[seg].ds_addr & bmask) == (curaddr & bmask)))
392 segs[seg].ds_len += sgsize;
394 if (++seg >= dmat->dt_nsegments)
396 segs[seg].ds_addr = curaddr;
397 segs[seg].ds_len = sgsize;
401 lastaddr = curaddr + sgsize;
407 *lastaddrp = lastaddr;
412 return (buflen != 0 ? EFBIG : 0); /* XXX better return value here? */
416 * Common function for loading a DMA map with a linear buffer. May
417 * be called by bus-specific DMA map load functions.
419 * Most SPARCs have IOMMUs in the bus controllers. In those cases
420 * they only need one segment and will use virtual addresses for DVMA.
421 * Those bus controllers should intercept these vectors and should
422 * *NEVER* call nexus_dmamap_load() which is used only by devices that
426 nexus_dmamap_load(bus_dma_tag_t dmat, bus_dmamap_t map, void *buf,
427 bus_size_t buflen, bus_dmamap_callback_t *callback, void *callback_arg,
433 error = _nexus_dmamap_load_buffer(dmat, buf, buflen, NULL, flags,
434 &lastaddr, dmat->dt_segments, &nsegs, 1);
437 (*callback)(callback_arg, dmat->dt_segments, nsegs + 1, 0);
438 map->dm_flags |= DMF_LOADED;
440 (*callback)(callback_arg, NULL, 0, error);
446 * Like nexus_dmamap_load(), but for mbufs.
449 nexus_dmamap_load_mbuf(bus_dma_tag_t dmat, bus_dmamap_t map, struct mbuf *m0,
450 bus_dmamap_callback2_t *callback, void *callback_arg, int flags)
458 if (m0->m_pkthdr.len <= dmat->dt_maxsize) {
460 bus_addr_t lastaddr = 0;
463 for (m = m0; m != NULL && error == 0; m = m->m_next) {
465 error = _nexus_dmamap_load_buffer(dmat,
466 m->m_data, m->m_len,NULL, flags, &lastaddr,
467 dmat->dt_segments, &nsegs, first);
476 /* force "no valid mappings" in callback */
477 (*callback)(callback_arg, dmat->dt_segments, 0, 0, error);
479 map->dm_flags |= DMF_LOADED;
480 (*callback)(callback_arg, dmat->dt_segments, nsegs + 1,
481 m0->m_pkthdr.len, error);
487 nexus_dmamap_load_mbuf_sg(bus_dma_tag_t dmat, bus_dmamap_t map, struct mbuf *m0,
488 bus_dma_segment_t *segs, int *nsegs, int flags)
496 if (m0->m_pkthdr.len <= dmat->dt_maxsize) {
498 bus_addr_t lastaddr = 0;
501 for (m = m0; m != NULL && error == 0; m = m->m_next) {
503 error = _nexus_dmamap_load_buffer(dmat,
504 m->m_data, m->m_len,NULL, flags, &lastaddr,
518 * Like nexus_dmamap_load(), but for uios.
521 nexus_dmamap_load_uio(bus_dma_tag_t dmat, bus_dmamap_t map, struct uio *uio,
522 bus_dmamap_callback2_t *callback, void *callback_arg, int flags)
525 int nsegs, error, first, i;
528 struct thread *td = NULL;
530 resid = uio->uio_resid;
533 if (uio->uio_segflg == UIO_USERSPACE) {
535 KASSERT(td != NULL, ("%s: USERSPACE but no proc", __func__));
541 for (i = 0; i < uio->uio_iovcnt && resid != 0 && !error; i++) {
543 * Now at the first iovec to load. Load each iovec
544 * until we have exhausted the residual count.
547 resid < iov[i].iov_len ? resid : iov[i].iov_len;
548 caddr_t addr = (caddr_t) iov[i].iov_base;
551 error = _nexus_dmamap_load_buffer(dmat, addr, minlen,
552 td, flags, &lastaddr, dmat->dt_segments, &nsegs,
561 /* force "no valid mappings" in callback */
562 (*callback)(callback_arg, dmat->dt_segments, 0, 0, error);
564 map->dm_flags |= DMF_LOADED;
565 (*callback)(callback_arg, dmat->dt_segments, nsegs + 1,
566 uio->uio_resid, error);
572 * Common function for unloading a DMA map. May be called by
573 * bus-specific DMA map unload functions.
576 nexus_dmamap_unload(bus_dma_tag_t dmat, bus_dmamap_t map)
579 map->dm_flags &= ~DMF_LOADED;
583 * Common function for DMA map synchronization. May be called
584 * by bus-specific DMA map synchronization functions.
587 nexus_dmamap_sync(bus_dma_tag_t dmat, bus_dmamap_t map, bus_dmasync_op_t op)
591 * We sync out our caches, but the bus must do the same.
593 * Actually a #Sync is expensive. We should optimize.
595 if ((op & BUS_DMASYNC_PREREAD) || (op & BUS_DMASYNC_PREWRITE)) {
597 * Don't really need to do anything, but flush any pending
602 if (op & BUS_DMASYNC_POSTWRITE) {
603 /* Nothing to do. Handled by the bus controller. */
608 * Common function for DMA-safe memory allocation. May be called
609 * by bus-specific DMA memory allocation functions.
612 nexus_dmamem_alloc(bus_dma_tag_t dmat, void **vaddr, int flags,
617 if (flags & BUS_DMA_NOWAIT)
621 if (flags & BUS_DMA_ZERO)
626 * (dmat->dt_alignment < dmat->dt_maxsize) is just a quick hack; the
627 * exact alignment guarantees of malloc need to be nailed down, and
628 * the code below should be rewritten to take that into account.
630 * In the meantime, we'll warn the user if malloc gets it wrong.
632 if (dmat->dt_maxsize <= PAGE_SIZE &&
633 dmat->dt_alignment < dmat->dt_maxsize)
634 *vaddr = malloc(dmat->dt_maxsize, M_DEVBUF, mflags);
637 * XXX use contigmalloc until it is merged into this
638 * facility and handles multi-seg allocations. Nobody
639 * is doing multi-seg allocations yet though.
641 *vaddr = contigmalloc(dmat->dt_maxsize, M_DEVBUF, mflags,
642 0ul, dmat->dt_lowaddr,
643 dmat->dt_alignment ? dmat->dt_alignment : 1UL,
648 if (vtophys(*vaddr) % dmat->dt_alignment)
649 printf("%s: failed to align memory properly.\n", __func__);
654 * Common function for freeing DMA-safe memory. May be called by
655 * bus-specific DMA memory free functions.
658 nexus_dmamem_free(bus_dma_tag_t dmat, void *vaddr, bus_dmamap_t map)
661 if (dmat->dt_maxsize <= PAGE_SIZE &&
662 dmat->dt_alignment < dmat->dt_maxsize)
663 free(vaddr, M_DEVBUF);
665 contigfree(vaddr, dmat->dt_maxsize, M_DEVBUF);
668 struct bus_dma_methods nexus_dma_methods = {
670 nexus_dmamap_destroy,
672 nexus_dmamap_load_mbuf,
673 nexus_dmamap_load_mbuf_sg,
674 nexus_dmamap_load_uio,
681 struct bus_dma_tag nexus_dmatag = {
703 * Helpers to map/unmap bus memory
706 sparc64_bus_mem_map(bus_space_tag_t tag, bus_space_handle_t handle,
707 bus_size_t size, int flags, vm_offset_t vaddr, void **hp)
716 addr = (vm_offset_t)handle;
717 size = round_page(size);
719 printf("%s: zero size\n", __func__);
722 switch (tag->bst_type) {
723 case PCI_CONFIG_BUS_SPACE:
724 case PCI_IO_BUS_SPACE:
725 case PCI_MEMORY_BUS_SPACE:
733 if (!(flags & BUS_SPACE_MAP_CACHEABLE))
737 sva = trunc_page(vaddr);
739 if ((sva = kmem_alloc_nofault(kernel_map, size)) == 0)
740 panic("%s: cannot allocate virtual memory", __func__);
743 /* Preserve page offset. */
744 *hp = (void *)(sva | ((u_long)addr & PAGE_MASK));
746 pa = trunc_page(addr);
747 if ((flags & BUS_SPACE_MAP_READONLY) == 0)
753 pmap_kenter_flags(va, pa, pm_flags);
756 } while ((vsz -= PAGE_SIZE) > 0);
757 tlb_range_demap(kernel_pmap, sva, sva + size - 1);
762 sparc64_bus_mem_unmap(void *bh, bus_size_t size)
768 sva = trunc_page((vm_offset_t)bh);
769 endva = sva + round_page(size);
770 for (va = sva; va < endva; va += PAGE_SIZE)
771 pmap_kremove_flags(va);
772 tlb_range_demap(kernel_pmap, sva, sva + size - 1);
773 kmem_free(kernel_map, sva, size);
778 * Fake up a bus tag, for use by console drivers in early boot when the
779 * regular means to allocate resources are not yet available.
780 * Addr is the physical address of the desired start of the handle.
783 sparc64_fake_bustag(int space, bus_addr_t addr, struct bus_space_tag *ptag)
786 ptag->bst_cookie = NULL;
787 ptag->bst_parent = NULL;
788 ptag->bst_type = space;
789 ptag->bst_bus_barrier = nexus_bus_barrier;
794 * Base bus space handlers.
798 nexus_bus_barrier(bus_space_tag_t t, bus_space_handle_t h, bus_size_t offset,
799 bus_size_t size, int flags)
803 * We have lots of alternatives depending on whether we're
804 * synchronizing loads with loads, loads with stores, stores
805 * with loads, or stores with stores. The only ones that seem
806 * generic are #Sync and #MemIssue. I'll use #Sync for safety.
809 case BUS_SPACE_BARRIER_READ | BUS_SPACE_BARRIER_WRITE:
810 case BUS_SPACE_BARRIER_READ:
811 case BUS_SPACE_BARRIER_WRITE:
815 panic("%s: unknown flags", __func__);
820 struct bus_space_tag nexus_bustag = {
822 NULL, /* parent bus tag */
823 NEXUS_BUS_SPACE, /* type */
824 nexus_bus_barrier, /* bus_space_barrier */