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without Giant held. A quick outline of the locking strategy: Since all IOMMUs are synchronized, there is a single lock, iommu_mtx, which protects the hardware registers (where needed) and the global and per-IOMMU software states. As soon as the IOMMUs are divorced, each struct iommu_state will have its own mutex (and the remaining global state will be moved into the struct). The dvma rman has its own internal mutex; the TSB slots may only be accessed by the owner of the corresponding resource, so neither needs extra protection. Since there is a second access path to maps via LRU queues, the consumer- provided locking is not sufficient; therefore, each map which is on a queue is additionally protected by iommu_mtx (in part, there is one member which only the map owner may access). Each map on a queue may be accessed and removed from or repositioned in a queue in any context as long as the lock is held; only the owner may insert a map. To reduce lock contention, some bus_dma functions remove the map from the queue temporarily (on behalf of the map owner) for some operations and reinsert it when they are done. Shorter operations and operations which are not done on behalf of the lock owner are completely covered by the lock. To facilitate the locking, reorganize the streaming buffer handling; while being there, fix an old oversight which would cause the streaming buffer to always be flushed, regardless of whether streaming was enabled in the TSB entry. The streaming buffer is still disabled for now, since there are a number of drivers which lack critical bus_dmamp_sync() calls. Additional testing by: jake
91 lines
3.5 KiB
C
91 lines
3.5 KiB
C
/*-
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* Copyright (c) 1997, 1998 Justin T. Gibbs.
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* Copyright (c) 2002 by Thomas Moestl <tmm@FreeBSD.org>.
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
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* IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
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* OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
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* IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
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* INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
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* (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
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* SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
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* CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
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* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE
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* USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
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*
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* from: FreeBSD: src/sys/i386/i386/busdma_machdep.c,v 1.25 2002/01/05
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*
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* $FreeBSD$
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*/
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#ifndef _MACHINE_BUS_PRIVATE_H_
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#define _MACHINE_BUS_PRIVATE_H_
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#include <sys/queue.h>
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/*
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* Helpers
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*/
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int sparc64_bus_mem_map(bus_space_tag_t, bus_space_handle_t, bus_size_t,
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int, vm_offset_t, void **);
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int sparc64_bus_mem_unmap(void *, bus_size_t);
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bus_space_handle_t sparc64_fake_bustag(int, bus_addr_t, struct bus_space_tag *);
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/*
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* This is more or less arbitrary, except for the stack space consumed by
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* the segments array. Choose more than ((BUS_SPACE_MAXSIZE / PAGE_SIZE) + 1),
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* since in practice we could be map pages more than once.
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*/
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#define BUS_DMAMAP_NSEGS 64
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struct bus_dmamap_res {
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struct resource *dr_res;
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bus_size_t dr_used;
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SLIST_ENTRY(bus_dmamap_res) dr_link;
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};
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/*
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* Callers of the bus_dma interfaces must always protect their tags and maps
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* appropriately against concurrent access. However, when a map is on a LRU
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* queue, there is a second access path to it; for this case, the locking rules
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* are given in the parenthesized comments below:
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* q - locked by the mutex protecting the queue.
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* p - private to the owner of the map, no access through the queue.
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* * - comment refers to pointer target.
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* Only the owner of the map is allowed to insert the map into a queue. Removal
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* and repositioning (i.e. temporal removal and reinsertion) is allowed to all
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* if the queue lock is held.
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*/
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struct bus_dmamap {
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TAILQ_ENTRY(bus_dmamap) dm_maplruq; /* (q) */
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SLIST_HEAD(, bus_dmamap_res) dm_reslist; /* (q, *q) */
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int dm_onq; /* (q) */
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int dm_flags; /* (p) */
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};
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/* Flag values. */
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#define DMF_LOADED 1 /* Map is loaded */
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#define DMF_COHERENT 2 /* Coherent mapping requested */
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int sparc64_dma_alloc_map(bus_dma_tag_t dmat, bus_dmamap_t *mapp);
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void sparc64_dma_free_map(bus_dma_tag_t dmat, bus_dmamap_t map);
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/*
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* XXX: This is a kluge. It would be better to handle dma tags in a hierarchical
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* way, and have a BUS_GET_DMA_TAG(); however, since this is not currently the
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* case, save a root tag in the relevant bus attach function and use that.
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*/
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extern bus_dma_tag_t sparc64_root_dma_tag;
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#endif /* !_MACHINE_BUS_PRIVATE_H_ */
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