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/* $Header: /var/lib/cvsd/repos/coherent/coherent/d/286_KERNEL/USRSRC/286/dmac.c,v 1.1.1.1 2019/05/29 04:56:39 root Exp $ */
/* (lgl-
 *	The information contained herein is a trade secret of Mark Williams
 *	Company, and  is confidential information.  It is provided  under a
 *	license agreement,  and may be  copied or disclosed  only under the
 *	terms of  that agreement.  Any  reproduction or disclosure  of this
 *	material without the express written authorization of Mark Williams
 *	Company or persuant to the license agreement is unlawful.
 *
 *	COHERENT Version 2.3.37
 *	Copyright (c) 1982, 1983, 1984.
 *	An unpublished work by Mark Williams Company, Chicago.
 *	All rights reserved.
 -lgl) */
/*
 * The routines in this file
 * deal with the 8237 programmable
 * DMA controller on the system board.
 *
 * $Log: dmac.c,v $
 * Revision 1.1.1.1  2019/05/29 04:56:39  root
 * coherent
 *
 * Revision 1.1	88/03/24  09:33:31 	src
 * Initial revision
 * 
 * 86/12/18	Allan Cornish		/usr/src/sys/i8086/ibm_at/dmac.c
 * Full support for DMA channels 5..7 added.
 */
#include	<sys/types.h>
#include	<sys/dmac.h>

/*
 * This table maps channel
 * numbers into DMA page address
 * register ports. The wiring of the
 * RA lines on the 74LS670 is a bit
 * strange.
 */
static	int	dmaport[8] = {
	DMAPAGE+7,			/* 0 (Free) */
	DMAPAGE+3,			/* 1 (Free) */
	DMAPAGE+1,			/* 2 (Floppy) */
	DMAPAGE+2,			/* 3 (Free) */
	DMAPAGE+15,			/* 4 (Cascade) */
	DMAPAGE+11,			/* 5 */
	DMAPAGE+9,			/* 6 */
	DMAPAGE+10			/* 7 */
};

/*
 * Program the channel of the
 * 8237 DMA controller specified by
 * "chan". The "paddr" is a 20 bit
 * physical address. The "count" is
 * the byte count. The "wflag" is
 * true if this is a write, from the
 * point of view of the device.
 * True return if the mapping can be
 * set up, given the 64K limits.
 * The "count" is predecremented, so
 * that backplane "+T/C" is issued at
 * the expected point in time.
 */
dmaon(chan, paddr, count, wflag)
register int	chan;
paddr_t		paddr;
unsigned	count;
{
	register int	port;
	register int	s;

	/*
	 * Change from 0 based transfer count to -1 based.
	 */
	count--;

	/*
	 * Select byte/word transfer.
	 * Channels 0-4 use byte transfer.
	 * Channels 5-7 use word transfers, with low 17 addr bits right shifted.
	 */
	if ( chan >= 5 ) {
		count >>= 1;
		paddr >>= 1;
		paddr  += (paddr & 0xFF0000L);
	}

	/*
	 * Check for DMA straddle.
	 */
	if ( dmaseg(paddr) != dmaseg(paddr+count) )
		return (0);

	s = sphi();

	/*
	 * Select DMA controller.
	 */
	if ( chan < 4 ) {
		port = DMA;

		/*
		 * Program for dma read/write operation.
		 */
		if ( wflag != 0 )
			outb( port + (SETMODE * 1), (chan & 3) | RDMEM );
		else
			outb( port + (SETMODE * 1), (chan & 3) | WRMEM );
		outb( port + (CLEARFL * 1), 0 );
	}
	else {
		port = SDMA;

		/*
		 * Program for dma read/write operation.
		 */
		if ( wflag != 0 )
			outb( SDMA + (SETMODE * 2), (chan & 3) | RDMEM );
		else
			outb( SDMA + (SETMODE * 2), (chan & 3) | WRMEM );
		outb( SDMA + (CLEARFL * 2), 0 );
	}

	/*
	 * Select memory bank.
	 */
	outb( dmaport[chan], (int)(paddr >> 16) );

	if ( chan < 4 )
		port += ((chan & 3) << 1);
	else
		port += ((chan & 3) << 2);

	/*
	 * Program memory offset in bank.
	 */
	outb( port, ((int) paddr) >> 0 );
	outb( port, ((int) paddr) >> 8 );

	port++;
	if ( chan >= 4 )
		port++;

	/*
	 * Program transfer count.
	 */
	outb( port, count >> 0 );
	outb( port, count >> 8 );

	spl(s);
	return (1);
}

/*
 * dmago( chan ) - initiate dma transfer
 */
dmago( chan )
register int chan;
{
	/*
	 * Enable dma transfers.
	 */
	if ( chan < 4 )
		outb( DMA  + (SETMASK * 1), (chan & 3) | MASKOFF );
	else
		outb( SDMA + (SETMASK * 2), (chan & 3) | MASKOFF );
}

/*
 * dmaoff( chan ) - turn dma channel off, return residual count
 */
dmaoff( chan )
register int chan;
{
	register int port;
	register int count;
	int s;

	/*
	 * Disable DMA transfers.
	 * Obtain the -1 based residual count.
	 */
	s = sphi();
	if ( chan < 4 ) {
		outb(  DMA + (SETMASK * 1), (chan & 3) | MASKON );
		port = DMA + ((chan & 3) << 1) + 1;
	}
	else {
		outb(  SDMA + (SETMASK * 2), (chan & 3) | MASKON );
		port = SDMA + ((chan & 3) << 2) + 2;
	}
	count  = inb(port);
	count += inb(port) << 8;
	spl( s );

	/*
	 * Convert residual from -1 based to 0 based.
	 */
	count++;

	/*
	 * Convert residual from word based to byte based.
	 */
	if ( chan >= 5 )
		count <<= 1;

	/*
	 * Return residual count in bytes.
	 */
	return count;
}

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