56 lines
1.7 KiB
C
56 lines
1.7 KiB
C
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/*
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* include/asm-xtensa/dma.h
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*
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* This file is subject to the terms and conditions of the GNU General Public
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* License. See the file "COPYING" in the main directory of this archive
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* for more details.
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*
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* Copyright (C) 2003 - 2005 Tensilica Inc.
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*/
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#ifndef _XTENSA_DMA_H
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#define _XTENSA_DMA_H
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#include <asm/io.h> /* need byte IO */
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/*
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* This is only to be defined if we have PC-like DMA.
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* By default this is not true on an Xtensa processor,
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* however on boards with a PCI bus, such functionality
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* might be emulated externally.
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*
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* NOTE: there still exists driver code that assumes
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* this is defined, eg. drivers/sound/soundcard.c (as of 2.4).
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*/
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#define MAX_DMA_CHANNELS 8
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/*
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* The maximum virtual address to which DMA transfers
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* can be performed on this platform.
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*
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* NOTE: This is board (platform) specific, not processor-specific!
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*
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* NOTE: This assumes DMA transfers can only be performed on
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* the section of physical memory contiguously mapped in virtual
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* space for the kernel. For the Xtensa architecture, this
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* means the maximum possible size of this DMA area is
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* the size of the statically mapped kernel segment
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* (XCHAL_KSEG_{CACHED,BYPASS}_SIZE), ie. 128 MB.
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*
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* NOTE: When the entire KSEG area is DMA capable, we subtract
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* one from the max address so that the virt_to_phys() macro
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* works correctly on the address (otherwise the address
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* enters another area, and virt_to_phys() may not return
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* the value desired).
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*/
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#ifndef MAX_DMA_ADDRESS
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#define MAX_DMA_ADDRESS (PAGE_OFFSET + XCHAL_KIO_SIZE - 1)
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#endif
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/* Reserve and release a DMA channel */
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extern int request_dma(unsigned int dmanr, const char * device_id);
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extern void free_dma(unsigned int dmanr);
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#endif
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