44 lines
1.1 KiB
C
44 lines
1.1 KiB
C
/* $NetBSD: isadma.c,v 1.2 2008/12/14 17:03:43 christos Exp $ */
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/* from: NetBSD:dev/isa/isadma.c */
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#include <sys/types.h>
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#include <machine/pio.h>
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#include <lib/libsa/stand.h>
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#include "isadmavar.h"
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#define IO_DMA1 0x000 /* 8237A DMA Controller #1 */
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#define IO_DMA2 0x0C0 /* 8237A DMA Controller #2 */
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#define DMA37MD_CASCADE 0xc0 /* cascade mode */
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#define DMA1_SMSK (IO_DMA1 + 1*10) /* single mask register */
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#define DMA1_MODE (IO_DMA1 + 1*11) /* mode register */
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#define DMA2_SMSK (IO_DMA2 + 2*10) /* single mask register */
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#define DMA2_MODE (IO_DMA2 + 2*11) /* mode register */
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/*
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* isa_dmacascade(): program 8237 DMA controller channel to accept
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* external dma control by a board.
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*/
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void
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isa_dmacascade(int chan)
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{
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#ifdef ISADMA_DEBUG
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if (chan < 0 || chan > 7)
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panic("isa_dmacascade: impossible request");
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#endif
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/* set dma channel mode, and set dma channel mode */
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if ((chan & 4) == 0) {
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outb(DMA1_MODE, chan | DMA37MD_CASCADE);
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outb(DMA1_SMSK, chan);
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} else {
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chan &= 3;
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outb(DMA2_MODE, chan | DMA37MD_CASCADE);
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outb(DMA2_SMSK, chan);
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}
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}
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