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.
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.
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.
38 * Copyright (c) 1992, 1993
39 * The Regents of the University of California. All rights reserved.
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.
45 * Redistribution and use in source and binary forms, with or without
46 * modification, are permitted provided that the following conditions
48 * 1. Redistributions of source code must retain the above copyright
49 * notice, this list of conditions and the following disclaimer.
50 * 2. Redistributions in binary form must reproduce the above copyright
51 * notice, this list of conditions and the following disclaimer in the
52 * documentation and/or other materials provided with the distribution.
53 * 4. Neither the name of the University nor the names of its contributors
54 * may be used to endorse or promote products derived from this software
55 * without specific prior written permission.
57 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
58 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
59 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
60 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
61 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
62 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
63 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
64 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
65 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
66 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
70 * Copyright (c) 1997, 1998 Justin T. Gibbs.
71 * All rights reserved.
72 * Copyright 2001 by Thomas Moestl <tmm@FreeBSD.org>. All rights reserved.
74 * Redistribution and use in source and binary forms, with or without
75 * modification, are permitted provided that the following conditions
77 * 1. Redistributions of source code must retain the above copyright
78 * notice, this list of conditions, and the following disclaimer,
79 * without modification, immediately at the beginning of the file.
80 * 2. The name of the author may not be used to endorse or promote products
81 * derived from this software without specific prior written permission.
83 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
84 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
85 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
86 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE FOR
87 * ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
88 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
89 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
90 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
91 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
92 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
95 * from: @(#)machdep.c 8.6 (Berkeley) 1/14/94
96 * from: NetBSD: machdep.c,v 1.111 2001/09/15 07:13:40 eeh Exp
98 * from: FreeBSD: src/sys/i386/i386/busdma_machdep.c,v 1.24 2001/08/15
101 #include <sys/cdefs.h>
102 __FBSDID("$FreeBSD$");
104 #include <sys/param.h>
106 #include <sys/lock.h>
107 #include <sys/malloc.h>
108 #include <sys/mbuf.h>
109 #include <sys/mutex.h>
110 #include <sys/proc.h>
112 #include <sys/systm.h>
116 #include <vm/vm_extern.h>
117 #include <vm/vm_kern.h>
118 #include <vm/vm_page.h>
119 #include <vm/vm_param.h>
120 #include <vm/vm_map.h>
122 #include <machine/asi.h>
123 #include <machine/atomic.h>
124 #include <machine/bus.h>
125 #include <machine/bus_private.h>
126 #include <machine/cache.h>
127 #include <machine/smp.h>
128 #include <machine/tlb.h>
130 static void nexus_bus_barrier(bus_space_tag_t, bus_space_handle_t,
131 bus_size_t, bus_size_t, int);
133 /* ASIs for bus access */
134 const int bus_type_asi[] = {
135 ASI_PHYS_BYPASS_EC_WITH_EBIT, /* nexus */
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 */
143 const int bus_stream_asi[] = {
144 ASI_PHYS_BYPASS_EC_WITH_EBIT, /* nexus */
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 */
153 * Convenience function for manipulating driver locks from busdma (during
154 * busdma_swi, for example). Drivers that don't provide their own locks
155 * should specify &Giant to dmat->lockfuncarg. Drivers that use their own
156 * non-mutex locking scheme don't have to use this at all.
159 busdma_lock_mutex(void *arg, bus_dma_lock_op_t op)
163 dmtx = (struct mtx *)arg;
172 panic("Unknown operation 0x%x for busdma_lock_mutex!", op);
177 * dflt_lock should never get called. It gets put into the dma tag when
178 * lockfunc == NULL, which is only valid if the maps that are associated
179 * with the tag are meant to never be defered.
180 * XXX Should have a way to identify which driver is responsible here.
183 dflt_lock(void *arg, bus_dma_lock_op_t op)
186 panic("driver error: busdma dflt_lock called");
188 printf("DRIVER_ERROR: busdma dflt_lock called\n");
193 * Allocate a device specific dma_tag.
196 bus_dma_tag_create(bus_dma_tag_t parent, bus_size_t alignment,
197 bus_size_t boundary, bus_addr_t lowaddr, bus_addr_t highaddr,
198 bus_dma_filter_t *filter, void *filterarg, bus_size_t maxsize,
199 int nsegments, bus_size_t maxsegsz, int flags, bus_dma_lock_t *lockfunc,
200 void *lockfuncarg, bus_dma_tag_t *dmat)
202 bus_dma_tag_t newtag;
204 /* Return a NULL tag on failure */
207 /* Enforce the usage of BUS_GET_DMA_TAG(). */
209 panic("%s: parent DMA tag NULL", __func__);
211 newtag = (bus_dma_tag_t)malloc(sizeof(*newtag), M_DEVBUF, M_NOWAIT);
216 * The method table pointer and the cookie need to be taken over from
219 newtag->dt_cookie = parent->dt_cookie;
220 newtag->dt_mt = parent->dt_mt;
222 newtag->dt_parent = parent;
223 newtag->dt_alignment = alignment;
224 newtag->dt_boundary = boundary;
225 newtag->dt_lowaddr = trunc_page((vm_offset_t)lowaddr) + (PAGE_SIZE - 1);
226 newtag->dt_highaddr = trunc_page((vm_offset_t)highaddr) +
228 newtag->dt_filter = filter;
229 newtag->dt_filterarg = filterarg;
230 newtag->dt_maxsize = maxsize;
231 newtag->dt_nsegments = nsegments;
232 newtag->dt_maxsegsz = maxsegsz;
233 newtag->dt_flags = flags;
234 newtag->dt_ref_count = 1; /* Count ourselves */
235 newtag->dt_map_count = 0;
237 if (lockfunc != NULL) {
238 newtag->dt_lockfunc = lockfunc;
239 newtag->dt_lockfuncarg = lockfuncarg;
241 newtag->dt_lockfunc = dflt_lock;
242 newtag->dt_lockfuncarg = NULL;
245 newtag->dt_segments = NULL;
247 /* Take into account any restrictions imposed by our parent tag. */
248 newtag->dt_lowaddr = ulmin(parent->dt_lowaddr, newtag->dt_lowaddr);
249 newtag->dt_highaddr = ulmax(parent->dt_highaddr, newtag->dt_highaddr);
250 if (newtag->dt_boundary == 0)
251 newtag->dt_boundary = parent->dt_boundary;
252 else if (parent->dt_boundary != 0)
253 newtag->dt_boundary = ulmin(parent->dt_boundary,
254 newtag->dt_boundary);
255 atomic_add_int(&parent->dt_ref_count, 1);
257 if (newtag->dt_boundary > 0)
258 newtag->dt_maxsegsz = ulmin(newtag->dt_maxsegsz,
259 newtag->dt_boundary);
266 bus_dma_tag_destroy(bus_dma_tag_t dmat)
268 bus_dma_tag_t parent;
271 if (dmat->dt_map_count != 0)
273 while (dmat != NULL) {
274 parent = dmat->dt_parent;
275 atomic_subtract_int(&dmat->dt_ref_count, 1);
276 if (dmat->dt_ref_count == 0) {
277 if (dmat->dt_segments != NULL)
278 free(dmat->dt_segments, M_DEVBUF);
279 free(dmat, M_DEVBUF);
281 * Last reference count, so
282 * release our reference
283 * count on our parent.
293 /* Allocate/free a tag, and do the necessary management work. */
295 sparc64_dma_alloc_map(bus_dma_tag_t dmat, bus_dmamap_t *mapp)
298 if (dmat->dt_segments == NULL) {
299 dmat->dt_segments = (bus_dma_segment_t *)malloc(
300 sizeof(bus_dma_segment_t) * dmat->dt_nsegments, M_DEVBUF,
302 if (dmat->dt_segments == NULL)
305 *mapp = malloc(sizeof(**mapp), M_DEVBUF, M_NOWAIT | M_ZERO);
309 SLIST_INIT(&(*mapp)->dm_reslist);
310 dmat->dt_map_count++;
315 sparc64_dma_free_map(bus_dma_tag_t dmat, bus_dmamap_t map)
319 dmat->dt_map_count--;
323 nexus_dmamap_create(bus_dma_tag_t dmat, int flags, bus_dmamap_t *mapp)
326 return (sparc64_dma_alloc_map(dmat, mapp));
330 nexus_dmamap_destroy(bus_dma_tag_t dmat, bus_dmamap_t map)
333 sparc64_dma_free_map(dmat, map);
338 * Utility function to load a linear buffer. lastaddrp holds state
339 * between invocations (for multiple-buffer loads). segp contains
340 * the starting segment on entrace, and the ending segment on exit.
341 * first indicates if this is the first invocation of this function.
344 _nexus_dmamap_load_buffer(bus_dma_tag_t dmat, void *buf, bus_size_t buflen,
345 struct thread *td, int flags, bus_addr_t *lastaddrp,
346 bus_dma_segment_t *segs, int *segp, int first)
349 bus_addr_t curaddr, lastaddr, baddr, bmask;
350 vm_offset_t vaddr = (vm_offset_t)buf;
355 pmap = vmspace_pmap(td->td_proc->p_vmspace);
359 lastaddr = *lastaddrp;
360 bmask = ~(dmat->dt_boundary - 1);
362 for (seg = *segp; buflen > 0 ; ) {
364 * Get the physical address for this segment.
367 curaddr = pmap_extract(pmap, vaddr);
369 curaddr = pmap_kextract(vaddr);
372 * Compute the segment size, and adjust counts.
374 sgsize = PAGE_SIZE - ((u_long)curaddr & PAGE_MASK);
375 if (sgsize > dmat->dt_maxsegsz)
376 sgsize = dmat->dt_maxsegsz;
381 * Make sure we don't cross any boundaries.
383 if (dmat->dt_boundary > 0) {
384 baddr = (curaddr + dmat->dt_boundary) & bmask;
385 if (sgsize > (baddr - curaddr))
386 sgsize = (baddr - curaddr);
390 * Insert chunk into a segment, coalescing with
391 * previous segment if possible.
394 segs[seg].ds_addr = curaddr;
395 segs[seg].ds_len = sgsize;
398 if (curaddr == lastaddr &&
399 (segs[seg].ds_len + sgsize) <= dmat->dt_maxsegsz &&
400 (dmat->dt_boundary == 0 ||
401 (segs[seg].ds_addr & bmask) == (curaddr & bmask)))
402 segs[seg].ds_len += sgsize;
404 if (++seg >= dmat->dt_nsegments)
406 segs[seg].ds_addr = curaddr;
407 segs[seg].ds_len = sgsize;
411 lastaddr = curaddr + sgsize;
417 *lastaddrp = lastaddr;
422 return (buflen != 0 ? EFBIG : 0); /* XXX better return value here? */
426 * Common function for loading a DMA map with a linear buffer. May
427 * be called by bus-specific DMA map load functions.
429 * Most SPARCs have IOMMUs in the bus controllers. In those cases
430 * they only need one segment and will use virtual addresses for DVMA.
431 * Those bus controllers should intercept these vectors and should
432 * *NEVER* call nexus_dmamap_load() which is used only by devices that
436 nexus_dmamap_load(bus_dma_tag_t dmat, bus_dmamap_t map, void *buf,
437 bus_size_t buflen, bus_dmamap_callback_t *callback, void *callback_arg,
443 error = _nexus_dmamap_load_buffer(dmat, buf, buflen, NULL, flags,
444 &lastaddr, dmat->dt_segments, &nsegs, 1);
447 (*callback)(callback_arg, dmat->dt_segments, nsegs + 1, 0);
448 map->dm_flags |= DMF_LOADED;
450 (*callback)(callback_arg, NULL, 0, error);
456 * Like nexus_dmamap_load(), but for mbufs.
459 nexus_dmamap_load_mbuf(bus_dma_tag_t dmat, bus_dmamap_t map, struct mbuf *m0,
460 bus_dmamap_callback2_t *callback, void *callback_arg, int flags)
468 if (m0->m_pkthdr.len <= dmat->dt_maxsize) {
470 bus_addr_t lastaddr = 0;
473 for (m = m0; m != NULL && error == 0; m = m->m_next) {
475 error = _nexus_dmamap_load_buffer(dmat,
476 m->m_data, m->m_len,NULL, flags, &lastaddr,
477 dmat->dt_segments, &nsegs, first);
486 /* force "no valid mappings" in callback */
487 (*callback)(callback_arg, dmat->dt_segments, 0, 0, error);
489 map->dm_flags |= DMF_LOADED;
490 (*callback)(callback_arg, dmat->dt_segments, nsegs + 1,
491 m0->m_pkthdr.len, error);
497 nexus_dmamap_load_mbuf_sg(bus_dma_tag_t dmat, bus_dmamap_t map, struct mbuf *m0,
498 bus_dma_segment_t *segs, int *nsegs, int flags)
506 if (m0->m_pkthdr.len <= dmat->dt_maxsize) {
508 bus_addr_t lastaddr = 0;
511 for (m = m0; m != NULL && error == 0; m = m->m_next) {
513 error = _nexus_dmamap_load_buffer(dmat,
514 m->m_data, m->m_len,NULL, flags, &lastaddr,
528 * Like nexus_dmamap_load(), but for uios.
531 nexus_dmamap_load_uio(bus_dma_tag_t dmat, bus_dmamap_t map, struct uio *uio,
532 bus_dmamap_callback2_t *callback, void *callback_arg, int flags)
535 int nsegs, error, first, i;
538 struct thread *td = NULL;
540 resid = uio->uio_resid;
543 if (uio->uio_segflg == UIO_USERSPACE) {
545 KASSERT(td != NULL, ("%s: USERSPACE but no proc", __func__));
551 for (i = 0; i < uio->uio_iovcnt && resid != 0 && !error; i++) {
553 * Now at the first iovec to load. Load each iovec
554 * until we have exhausted the residual count.
557 resid < iov[i].iov_len ? resid : iov[i].iov_len;
558 caddr_t addr = (caddr_t) iov[i].iov_base;
561 error = _nexus_dmamap_load_buffer(dmat, addr, minlen,
562 td, flags, &lastaddr, dmat->dt_segments, &nsegs,
571 /* force "no valid mappings" in callback */
572 (*callback)(callback_arg, dmat->dt_segments, 0, 0, error);
574 map->dm_flags |= DMF_LOADED;
575 (*callback)(callback_arg, dmat->dt_segments, nsegs + 1,
576 uio->uio_resid, error);
582 * Common function for unloading a DMA map. May be called by
583 * bus-specific DMA map unload functions.
586 nexus_dmamap_unload(bus_dma_tag_t dmat, bus_dmamap_t map)
589 map->dm_flags &= ~DMF_LOADED;
593 * Common function for DMA map synchronization. May be called
594 * by bus-specific DMA map synchronization functions.
597 nexus_dmamap_sync(bus_dma_tag_t dmat, bus_dmamap_t map, bus_dmasync_op_t op)
601 * We sync out our caches, but the bus must do the same.
603 * Actually a #Sync is expensive. We should optimize.
605 if ((op & BUS_DMASYNC_PREREAD) || (op & BUS_DMASYNC_PREWRITE)) {
607 * Don't really need to do anything, but flush any pending
613 /* Should not be needed. */
614 if (op & BUS_DMASYNC_POSTREAD) {
615 ecache_flush((vm_offset_t)map->buf,
616 (vm_offset_t)map->buf + map->buflen - 1);
619 if (op & BUS_DMASYNC_POSTWRITE) {
620 /* Nothing to do. Handled by the bus controller. */
625 * Common function for DMA-safe memory allocation. May be called
626 * by bus-specific DMA memory allocation functions.
629 nexus_dmamem_alloc(bus_dma_tag_t dmat, void **vaddr, int flags,
634 if (flags & BUS_DMA_NOWAIT)
638 if (flags & BUS_DMA_ZERO)
641 if ((dmat->dt_maxsize <= PAGE_SIZE)) {
642 *vaddr = malloc(dmat->dt_maxsize, M_DEVBUF, mflags);
645 * XXX use contigmalloc until it is merged into this
646 * facility and handles multi-seg allocations. Nobody
647 * is doing multi-seg allocations yet though.
649 *vaddr = contigmalloc(dmat->dt_maxsize, M_DEVBUF, mflags,
650 0ul, dmat->dt_lowaddr,
651 dmat->dt_alignment ? dmat->dt_alignment : 1UL,
660 * Common function for freeing DMA-safe memory. May be called by
661 * bus-specific DMA memory free functions.
664 nexus_dmamem_free(bus_dma_tag_t dmat, void *vaddr, bus_dmamap_t map)
667 if ((dmat->dt_maxsize <= PAGE_SIZE))
668 free(vaddr, M_DEVBUF);
670 contigfree(vaddr, dmat->dt_maxsize, M_DEVBUF);
674 struct bus_dma_methods nexus_dma_methods = {
676 nexus_dmamap_destroy,
678 nexus_dmamap_load_mbuf,
679 nexus_dmamap_load_mbuf_sg,
680 nexus_dmamap_load_uio,
687 struct bus_dma_tag nexus_dmatag = {
709 * Helpers to map/unmap bus memory
712 sparc64_bus_mem_map(bus_space_tag_t tag, bus_space_handle_t handle,
713 bus_size_t size, int flags, vm_offset_t vaddr, void **hp)
722 addr = (vm_offset_t)handle;
723 size = round_page(size);
725 printf("%s: zero size\n", __func__);
728 switch (tag->bst_type) {
729 case PCI_CONFIG_BUS_SPACE:
730 case PCI_IO_BUS_SPACE:
731 case PCI_MEMORY_BUS_SPACE:
739 if (!(flags & BUS_SPACE_MAP_CACHEABLE))
743 sva = trunc_page(vaddr);
745 if ((sva = kmem_alloc_nofault(kernel_map, size)) == 0)
746 panic("%s: cannot allocate virtual memory", __func__);
749 /* Preserve page offset. */
750 *hp = (void *)(sva | ((u_long)addr & PAGE_MASK));
752 pa = trunc_page(addr);
753 if ((flags & BUS_SPACE_MAP_READONLY) == 0)
759 pmap_kenter_flags(va, pa, pm_flags);
762 } while ((vsz -= PAGE_SIZE) > 0);
763 tlb_range_demap(kernel_pmap, sva, sva + size - 1);
768 sparc64_bus_mem_unmap(void *bh, bus_size_t size)
774 sva = trunc_page((vm_offset_t)bh);
775 endva = sva + round_page(size);
776 for (va = sva; va < endva; va += PAGE_SIZE)
777 pmap_kremove_flags(va);
778 tlb_range_demap(kernel_pmap, sva, sva + size - 1);
779 kmem_free(kernel_map, sva, size);
784 * Fake up a bus tag, for use by console drivers in early boot when the
785 * regular means to allocate resources are not yet available.
786 * Addr is the physical address of the desired start of the handle.
789 sparc64_fake_bustag(int space, bus_addr_t addr, struct bus_space_tag *ptag)
792 ptag->bst_cookie = NULL;
793 ptag->bst_parent = NULL;
794 ptag->bst_type = space;
795 ptag->bst_bus_barrier = nexus_bus_barrier;
800 * Base bus space handlers.
804 nexus_bus_barrier(bus_space_tag_t t, bus_space_handle_t h, bus_size_t offset,
805 bus_size_t size, int flags)
809 * We have lots of alternatives depending on whether we're
810 * synchronizing loads with loads, loads with stores, stores
811 * with loads, or stores with stores. The only ones that seem
812 * generic are #Sync and #MemIssue. I'll use #Sync for safety.
815 case BUS_SPACE_BARRIER_READ | BUS_SPACE_BARRIER_WRITE:
816 case BUS_SPACE_BARRIER_READ:
817 case BUS_SPACE_BARRIER_WRITE:
821 panic("%s: unknown flags", __func__);
826 struct bus_space_tag nexus_bustag = {
828 NULL, /* parent bus tag */
829 NEXUS_BUS_SPACE, /* type */
830 nexus_bus_barrier, /* bus_space_barrier */