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/smp.h>
120 #include <machine/tlb.h>
122 static void nexus_bus_barrier(bus_space_tag_t, bus_space_handle_t,
123 bus_size_t, bus_size_t, int);
125 /* ASIs for bus access */
126 const int bus_type_asi[] = {
127 ASI_REAL_IO, /* nexus */
128 ASI_REAL_IO, /* SBus */
129 ASI_REAL_IO_L, /* PCI configuration space */
130 ASI_REAL_IO_L, /* PCI memory space */
131 ASI_REAL_IO_L, /* PCI I/O space */
135 const int bus_stream_asi[] = {
136 ASI_REAL_IO, /* nexus */
137 ASI_REAL_IO, /* SBus */
138 ASI_REAL_IO, /* PCI configuration space */
139 ASI_REAL_IO, /* PCI memory space */
140 ASI_REAL_IO, /* PCI I/O space */
145 * Convenience function for manipulating driver locks from busdma (during
146 * busdma_swi, for example). Drivers that don't provide their own locks
147 * should specify &Giant to dmat->lockfuncarg. Drivers that use their own
148 * non-mutex locking scheme don't have to use this at all.
151 busdma_lock_mutex(void *arg, bus_dma_lock_op_t op)
155 dmtx = (struct mtx *)arg;
164 panic("Unknown operation 0x%x for busdma_lock_mutex!", op);
169 * dflt_lock should never get called. It gets put into the dma tag when
170 * lockfunc == NULL, which is only valid if the maps that are associated
171 * with the tag are meant to never be defered.
172 * XXX Should have a way to identify which driver is responsible here.
175 dflt_lock(void *arg, bus_dma_lock_op_t op)
178 panic("driver error: busdma dflt_lock called");
182 * Since there is no way for a device to obtain a dma tag from its parent
183 * we use this kluge to handle different the different supported bus systems.
184 * The sparc64_root_dma_tag is used as parent for tags that have none, so that
185 * the correct methods will be used.
187 bus_dma_tag_t sparc64_root_dma_tag;
190 * Allocate a device specific dma_tag.
193 bus_dma_tag_create(bus_dma_tag_t parent, bus_size_t alignment,
194 bus_size_t boundary, bus_addr_t lowaddr, bus_addr_t highaddr,
195 bus_dma_filter_t *filter, void *filterarg, bus_size_t maxsize,
196 int nsegments, bus_size_t maxsegsz, int flags, bus_dma_lock_t *lockfunc,
197 void *lockfuncarg, bus_dma_tag_t *dmat)
199 bus_dma_tag_t impptag;
200 bus_dma_tag_t newtag;
202 /* Return a NULL tag on failure */
205 newtag = (bus_dma_tag_t)malloc(sizeof(*newtag), M_DEVBUF, M_NOWAIT);
209 impptag = parent != NULL ? parent : sparc64_root_dma_tag;
211 * The method table pointer and the cookie need to be taken over from
212 * the parent or the root tag.
214 newtag->dt_cookie = impptag->dt_cookie;
215 newtag->dt_mt = impptag->dt_mt;
217 newtag->dt_parent = parent;
218 newtag->dt_alignment = alignment;
219 newtag->dt_boundary = boundary;
220 newtag->dt_lowaddr = trunc_page((vm_offset_t)lowaddr) + (PAGE_SIZE - 1);
221 newtag->dt_highaddr = trunc_page((vm_offset_t)highaddr) +
223 newtag->dt_filter = filter;
224 newtag->dt_filterarg = filterarg;
225 newtag->dt_maxsize = maxsize;
226 newtag->dt_nsegments = nsegments;
227 newtag->dt_maxsegsz = maxsegsz;
228 newtag->dt_flags = flags;
229 newtag->dt_ref_count = 1; /* Count ourselves */
230 newtag->dt_map_count = 0;
232 if (lockfunc != NULL) {
233 newtag->dt_lockfunc = lockfunc;
234 newtag->dt_lockfuncarg = lockfuncarg;
236 newtag->dt_lockfunc = dflt_lock;
237 newtag->dt_lockfuncarg = NULL;
240 newtag->dt_segments = NULL;
242 /* Take into account any restrictions imposed by our parent tag. */
243 if (parent != NULL) {
244 newtag->dt_lowaddr = ulmin(parent->dt_lowaddr,
246 newtag->dt_highaddr = ulmax(parent->dt_highaddr,
247 newtag->dt_highaddr);
248 if (newtag->dt_boundary == 0)
249 newtag->dt_boundary = parent->dt_boundary;
250 else if (parent->dt_boundary != 0)
251 newtag->dt_boundary = ulmin(parent->dt_boundary,
252 newtag->dt_boundary);
253 atomic_add_int(&parent->dt_ref_count, 1);
256 if (newtag->dt_boundary > 0)
257 newtag->dt_maxsegsz = ulmin(newtag->dt_maxsegsz,
258 newtag->dt_boundary);
265 bus_dma_tag_destroy(bus_dma_tag_t dmat)
267 bus_dma_tag_t parent;
270 if (dmat->dt_map_count != 0)
272 while (dmat != NULL) {
273 parent = dmat->dt_parent;
274 atomic_subtract_int(&dmat->dt_ref_count, 1);
275 if (dmat->dt_ref_count == 0) {
276 if (dmat->dt_segments != NULL)
277 free(dmat->dt_segments, M_DEVBUF);
278 free(dmat, M_DEVBUF);
280 * Last reference count, so
281 * release our reference
282 * count on our parent.
292 /* Allocate/free a tag, and do the necessary management work. */
294 sparc64_dma_alloc_map(bus_dma_tag_t dmat, bus_dmamap_t *mapp)
297 if (dmat->dt_segments == NULL) {
298 dmat->dt_segments = (bus_dma_segment_t *)malloc(
299 sizeof(bus_dma_segment_t) * dmat->dt_nsegments, M_DEVBUF,
301 if (dmat->dt_segments == NULL)
304 *mapp = malloc(sizeof(**mapp), M_DEVBUF, M_NOWAIT | M_ZERO);
308 SLIST_INIT(&(*mapp)->dm_reslist);
309 dmat->dt_map_count++;
314 sparc64_dma_free_map(bus_dma_tag_t dmat, bus_dmamap_t map)
318 dmat->dt_map_count--;
322 nexus_dmamap_create(bus_dma_tag_t dmat, int flags, bus_dmamap_t *mapp)
325 return (sparc64_dma_alloc_map(dmat, mapp));
329 nexus_dmamap_destroy(bus_dma_tag_t dmat, bus_dmamap_t map)
332 sparc64_dma_free_map(dmat, map);
337 * Utility function to load a linear buffer. lastaddrp holds state
338 * between invocations (for multiple-buffer loads). segp contains
339 * the starting segment on entrace, and the ending segment on exit.
340 * first indicates if this is the first invocation of this function.
343 _nexus_dmamap_load_buffer(bus_dma_tag_t dmat, void *buf, bus_size_t buflen,
344 struct thread *td, int flags, bus_addr_t *lastaddrp,
345 bus_dma_segment_t *segs, int *segp, int first)
348 bus_addr_t curaddr, lastaddr, baddr, bmask;
349 vm_offset_t vaddr = (vm_offset_t)buf;
354 pmap = vmspace_pmap(td->td_proc->p_vmspace);
358 lastaddr = *lastaddrp;
359 bmask = ~(dmat->dt_boundary - 1);
361 for (seg = *segp; buflen > 0 ; ) {
363 * Get the physical address for this segment.
366 curaddr = pmap_extract(pmap, vaddr);
368 curaddr = pmap_kextract(vaddr);
371 * Compute the segment size, and adjust counts.
373 sgsize = PAGE_SIZE - ((u_long)curaddr & PAGE_MASK);
374 if (sgsize > dmat->dt_maxsegsz)
375 sgsize = dmat->dt_maxsegsz;
380 * Make sure we don't cross any boundaries.
382 if (dmat->dt_boundary > 0) {
383 baddr = (curaddr + dmat->dt_boundary) & bmask;
384 if (sgsize > (baddr - curaddr))
385 sgsize = (baddr - curaddr);
389 * Insert chunk into a segment, coalescing with
390 * previous segment if possible.
393 segs[seg].ds_addr = curaddr;
394 segs[seg].ds_len = sgsize;
397 if (curaddr == lastaddr &&
398 (segs[seg].ds_len + sgsize) <= dmat->dt_maxsegsz &&
399 (dmat->dt_boundary == 0 ||
400 (segs[seg].ds_addr & bmask) == (curaddr & bmask)))
401 segs[seg].ds_len += sgsize;
403 if (++seg >= dmat->dt_nsegments)
405 segs[seg].ds_addr = curaddr;
406 segs[seg].ds_len = sgsize;
410 lastaddr = curaddr + sgsize;
416 *lastaddrp = lastaddr;
421 return (buflen != 0 ? EFBIG : 0); /* XXX better return value here? */
425 * Common function for loading a DMA map with a linear buffer. May
426 * be called by bus-specific DMA map load functions.
428 * Most SPARCs have IOMMUs in the bus controllers. In those cases
429 * they only need one segment and will use virtual addresses for DVMA.
430 * Those bus controllers should intercept these vectors and should
431 * *NEVER* call nexus_dmamap_load() which is used only by devices that
435 nexus_dmamap_load(bus_dma_tag_t dmat, bus_dmamap_t map, void *buf,
436 bus_size_t buflen, bus_dmamap_callback_t *callback, void *callback_arg,
442 error = _nexus_dmamap_load_buffer(dmat, buf, buflen, NULL, flags,
443 &lastaddr, dmat->dt_segments, &nsegs, 1);
446 (*callback)(callback_arg, dmat->dt_segments, nsegs + 1, 0);
447 map->dm_flags |= DMF_LOADED;
449 (*callback)(callback_arg, NULL, 0, error);
455 * Like nexus_dmamap_load(), but for mbufs.
458 nexus_dmamap_load_mbuf(bus_dma_tag_t dmat, bus_dmamap_t map, struct mbuf *m0,
459 bus_dmamap_callback2_t *callback, void *callback_arg, int flags)
467 if (m0->m_pkthdr.len <= dmat->dt_maxsize) {
469 bus_addr_t lastaddr = 0;
472 for (m = m0; m != NULL && error == 0; m = m->m_next) {
474 error = _nexus_dmamap_load_buffer(dmat,
475 m->m_data, m->m_len,NULL, flags, &lastaddr,
476 dmat->dt_segments, &nsegs, first);
485 /* force "no valid mappings" in callback */
486 (*callback)(callback_arg, dmat->dt_segments, 0, 0, error);
488 map->dm_flags |= DMF_LOADED;
489 (*callback)(callback_arg, dmat->dt_segments, nsegs + 1,
490 m0->m_pkthdr.len, error);
496 nexus_dmamap_load_mbuf_sg(bus_dma_tag_t dmat, bus_dmamap_t map, struct mbuf *m0,
497 bus_dma_segment_t *segs, int *nsegs, int flags)
505 if (m0->m_pkthdr.len <= dmat->dt_maxsize) {
507 bus_addr_t lastaddr = 0;
510 for (m = m0; m != NULL && error == 0; m = m->m_next) {
512 error = _nexus_dmamap_load_buffer(dmat,
513 m->m_data, m->m_len,NULL, flags, &lastaddr,
527 * Like nexus_dmamap_load(), but for uios.
530 nexus_dmamap_load_uio(bus_dma_tag_t dmat, bus_dmamap_t map, struct uio *uio,
531 bus_dmamap_callback2_t *callback, void *callback_arg, int flags)
534 int nsegs, error, first, i;
537 struct thread *td = NULL;
539 resid = uio->uio_resid;
542 if (uio->uio_segflg == UIO_USERSPACE) {
544 KASSERT(td != NULL, ("%s: USERSPACE but no proc", __func__));
550 for (i = 0; i < uio->uio_iovcnt && resid != 0 && !error; i++) {
552 * Now at the first iovec to load. Load each iovec
553 * until we have exhausted the residual count.
556 resid < iov[i].iov_len ? resid : iov[i].iov_len;
557 caddr_t addr = (caddr_t) iov[i].iov_base;
560 error = _nexus_dmamap_load_buffer(dmat, addr, minlen,
561 td, flags, &lastaddr, dmat->dt_segments, &nsegs,
570 /* force "no valid mappings" in callback */
571 (*callback)(callback_arg, dmat->dt_segments, 0, 0, error);
573 map->dm_flags |= DMF_LOADED;
574 (*callback)(callback_arg, dmat->dt_segments, nsegs + 1,
575 uio->uio_resid, error);
581 * Common function for unloading a DMA map. May be called by
582 * bus-specific DMA map unload functions.
585 nexus_dmamap_unload(bus_dma_tag_t dmat, bus_dmamap_t map)
588 map->dm_flags &= ~DMF_LOADED;
592 * Common function for DMA map synchronization. May be called
593 * by bus-specific DMA map synchronization functions.
596 nexus_dmamap_sync(bus_dma_tag_t dmat, bus_dmamap_t map, bus_dmasync_op_t op)
600 * We sync out our caches, but the bus must do the same.
602 * Actually a #Sync is expensive. We should optimize.
604 if ((op & BUS_DMASYNC_PREREAD) || (op & BUS_DMASYNC_PREWRITE)) {
606 * Don't really need to do anything, but flush any pending
612 /* Should not be needed. */
613 if (op & BUS_DMASYNC_POSTREAD) {
614 ecache_flush((vm_offset_t)map->buf,
615 (vm_offset_t)map->buf + map->buflen - 1);
618 if (op & BUS_DMASYNC_POSTWRITE) {
619 /* Nothing to do. Handled by the bus controller. */
624 * Common function for DMA-safe memory allocation. May be called
625 * by bus-specific DMA memory allocation functions.
628 nexus_dmamem_alloc(bus_dma_tag_t dmat, void **vaddr, int flags,
633 if (flags & BUS_DMA_NOWAIT)
637 if (flags & BUS_DMA_ZERO)
642 * (dmat->dt_alignment < dmat->dt_maxsize) is just a quick hack; the
643 * exact alignment guarantees of malloc need to be nailed down, and
644 * the code below should be rewritten to take that into account.
646 * In the meantime, we'll warn the user if malloc gets it wrong.
648 if (dmat->dt_maxsize <= PAGE_SIZE &&
649 dmat->dt_alignment < dmat->dt_maxsize)
650 *vaddr = malloc(dmat->dt_maxsize, M_DEVBUF, mflags);
653 * XXX use contigmalloc until it is merged into this
654 * facility and handles multi-seg allocations. Nobody
655 * is doing multi-seg allocations yet though.
657 *vaddr = contigmalloc(dmat->dt_maxsize, M_DEVBUF, mflags,
658 0ul, dmat->dt_lowaddr,
659 dmat->dt_alignment ? dmat->dt_alignment : 1UL,
664 if ((uintptr_t)*vaddr % dmat->dt_alignment)
665 printf("%s: failed to align memory properly.\n", __func__);
670 * Common function for freeing DMA-safe memory. May be called by
671 * bus-specific DMA memory free functions.
674 nexus_dmamem_free(bus_dma_tag_t dmat, void *vaddr, bus_dmamap_t map)
677 if (dmat->dt_maxsize <= PAGE_SIZE &&
678 dmat->dt_alignment < dmat->dt_maxsize)
679 free(vaddr, M_DEVBUF);
681 contigfree(vaddr, dmat->dt_maxsize, M_DEVBUF);
684 struct bus_dma_methods nexus_dma_methods = {
686 nexus_dmamap_destroy,
688 nexus_dmamap_load_mbuf,
689 nexus_dmamap_load_mbuf_sg,
690 nexus_dmamap_load_uio,
697 struct bus_dma_tag nexus_dmatag = {
706 0x3ffffffff, /* XXX */
708 0xffffffff, /* XXX */
719 * Helpers to map/unmap bus memory
722 sparc64_bus_mem_map(bus_space_tag_t tag, bus_space_handle_t handle,
723 bus_size_t size, int flags, vm_offset_t vaddr, void **hp)
733 addr = (vm_offset_t)handle;
734 size = round_page(size);
736 printf("%s: zero size\n", __func__);
739 switch (tag->bst_type) {
740 case PCI_CONFIG_BUS_SPACE:
741 case PCI_IO_BUS_SPACE:
742 case PCI_MEMORY_BUS_SPACE:
750 if (!(flags & BUS_SPACE_MAP_CACHEABLE))
754 sva = trunc_page(vaddr);
756 if ((sva = kmem_alloc_nofault(kernel_map, size)) == 0)
757 panic("%s: cannot allocate virtual memory", __func__);
760 /* Preserve page offset. */
761 *hp = (void *)(sva | ((u_long)addr & PAGE_MASK));
763 pa = trunc_page(addr);
764 if ((flags & BUS_SPACE_MAP_READONLY) == 0)
770 pmap_kenter_flags(va, pa, pm_flags);
773 } while ((vsz -= PAGE_SIZE) > 0);
774 tlb_range_demap(kernel_pmap, sva, sva + size - 1);
780 sparc64_bus_mem_unmap(void *bh, bus_size_t size)
787 sva = trunc_page((vm_offset_t)bh);
788 endva = sva + round_page(size);
789 for (va = sva; va < endva; va += PAGE_SIZE)
790 pmap_kremove_flags(va);
791 tlb_range_demap(kernel_pmap, sva, sva + size - 1);
792 kmem_free(kernel_map, sva, size);
798 * Fake up a bus tag, for use by console drivers in early boot when the
799 * regular means to allocate resources are not yet available.
800 * Addr is the physical address of the desired start of the handle.
803 sparc64_fake_bustag(int space, bus_addr_t addr, struct bus_space_tag *ptag)
806 ptag->bst_cookie = NULL;
807 ptag->bst_parent = NULL;
808 ptag->bst_type = space;
809 ptag->bst_bus_barrier = nexus_bus_barrier;
814 * Base bus space handlers.
818 nexus_bus_barrier(bus_space_tag_t t, bus_space_handle_t h, bus_size_t offset,
819 bus_size_t size, int flags)
823 * We have lots of alternatives depending on whether we're
824 * synchronizing loads with loads, loads with stores, stores
825 * with loads, or stores with stores. The only ones that seem
826 * generic are #Sync and #MemIssue. I'll use #Sync for safety.
829 case BUS_SPACE_BARRIER_READ | BUS_SPACE_BARRIER_WRITE:
830 case BUS_SPACE_BARRIER_READ:
831 case BUS_SPACE_BARRIER_WRITE:
835 panic("%s: unknown flags", __func__);
840 struct bus_space_tag nexus_bustag = {
842 NULL, /* parent bus tag */
843 NEXUS_BUS_SPACE, /* type */
844 nexus_bus_barrier, /* bus_space_barrier */