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Annotation of coherent/d/286_KERNEL/USRSRC/286/dmac.c, revision 1.1

1.1     ! root        1: /* $Header: /usr/src/sys/i8086/ibm_at/RCS/dmac.c,v 1.1 88/03/24 09:33:31 src Exp $ */
        !             2: /* (lgl-
        !             3:  *     The information contained herein is a trade secret of Mark Williams
        !             4:  *     Company, and  is confidential information.  It is provided  under a
        !             5:  *     license agreement,  and may be  copied or disclosed  only under the
        !             6:  *     terms of  that agreement.  Any  reproduction or disclosure  of this
        !             7:  *     material without the express written authorization of Mark Williams
        !             8:  *     Company or persuant to the license agreement is unlawful.
        !             9:  *
        !            10:  *     COHERENT Version 2.3.37
        !            11:  *     Copyright (c) 1982, 1983, 1984.
        !            12:  *     An unpublished work by Mark Williams Company, Chicago.
        !            13:  *     All rights reserved.
        !            14:  -lgl) */
        !            15: /*
        !            16:  * The routines in this file
        !            17:  * deal with the 8237 programmable
        !            18:  * DMA controller on the system board.
        !            19:  *
        !            20:  * $Log:       /usr/src/sys/i8086/ibm_at/RCS/dmac.c,v $
        !            21:  * Revision 1.1        88/03/24  09:33:31      src
        !            22:  * Initial revision
        !            23:  * 
        !            24:  * 86/12/18    Allan Cornish           /usr/src/sys/i8086/ibm_at/dmac.c
        !            25:  * Full support for DMA channels 5..7 added.
        !            26:  */
        !            27: #include       <sys/types.h>
        !            28: #include       <sys/dmac.h>
        !            29: 
        !            30: /*
        !            31:  * This table maps channel
        !            32:  * numbers into DMA page address
        !            33:  * register ports. The wiring of the
        !            34:  * RA lines on the 74LS670 is a bit
        !            35:  * strange.
        !            36:  */
        !            37: static int     dmaport[8] = {
        !            38:        DMAPAGE+7,                      /* 0 (Free) */
        !            39:        DMAPAGE+3,                      /* 1 (Free) */
        !            40:        DMAPAGE+1,                      /* 2 (Floppy) */
        !            41:        DMAPAGE+2,                      /* 3 (Free) */
        !            42:        DMAPAGE+15,                     /* 4 (Cascade) */
        !            43:        DMAPAGE+11,                     /* 5 */
        !            44:        DMAPAGE+9,                      /* 6 */
        !            45:        DMAPAGE+10                      /* 7 */
        !            46: };
        !            47: 
        !            48: /*
        !            49:  * Program the channel of the
        !            50:  * 8237 DMA controller specified by
        !            51:  * "chan". The "paddr" is a 20 bit
        !            52:  * physical address. The "count" is
        !            53:  * the byte count. The "wflag" is
        !            54:  * true if this is a write, from the
        !            55:  * point of view of the device.
        !            56:  * True return if the mapping can be
        !            57:  * set up, given the 64K limits.
        !            58:  * The "count" is predecremented, so
        !            59:  * that backplane "+T/C" is issued at
        !            60:  * the expected point in time.
        !            61:  */
        !            62: dmaon(chan, paddr, count, wflag)
        !            63: register int   chan;
        !            64: paddr_t                paddr;
        !            65: unsigned       count;
        !            66: {
        !            67:        register int    port;
        !            68:        register int    s;
        !            69: 
        !            70:        /*
        !            71:         * Change from 0 based transfer count to -1 based.
        !            72:         */
        !            73:        count--;
        !            74: 
        !            75:        /*
        !            76:         * Select byte/word transfer.
        !            77:         * Channels 0-4 use byte transfer.
        !            78:         * Channels 5-7 use word transfers, with low 17 addr bits right shifted.
        !            79:         */
        !            80:        if ( chan >= 5 ) {
        !            81:                count >>= 1;
        !            82:                paddr >>= 1;
        !            83:                paddr  += (paddr & 0xFF0000L);
        !            84:        }
        !            85: 
        !            86:        /*
        !            87:         * Check for DMA straddle.
        !            88:         */
        !            89:        if ( dmaseg(paddr) != dmaseg(paddr+count) )
        !            90:                return (0);
        !            91: 
        !            92:        s = sphi();
        !            93: 
        !            94:        /*
        !            95:         * Select DMA controller.
        !            96:         */
        !            97:        if ( chan < 4 ) {
        !            98:                port = DMA;
        !            99: 
        !           100:                /*
        !           101:                 * Program for dma read/write operation.
        !           102:                 */
        !           103:                if ( wflag != 0 )
        !           104:                        outb( port + (SETMODE * 1), (chan & 3) | RDMEM );
        !           105:                else
        !           106:                        outb( port + (SETMODE * 1), (chan & 3) | WRMEM );
        !           107:                outb( port + (CLEARFL * 1), 0 );
        !           108:        }
        !           109:        else {
        !           110:                port = SDMA;
        !           111: 
        !           112:                /*
        !           113:                 * Program for dma read/write operation.
        !           114:                 */
        !           115:                if ( wflag != 0 )
        !           116:                        outb( SDMA + (SETMODE * 2), (chan & 3) | RDMEM );
        !           117:                else
        !           118:                        outb( SDMA + (SETMODE * 2), (chan & 3) | WRMEM );
        !           119:                outb( SDMA + (CLEARFL * 2), 0 );
        !           120:        }
        !           121: 
        !           122:        /*
        !           123:         * Select memory bank.
        !           124:         */
        !           125:        outb( dmaport[chan], (int)(paddr >> 16) );
        !           126: 
        !           127:        if ( chan < 4 )
        !           128:                port += ((chan & 3) << 1);
        !           129:        else
        !           130:                port += ((chan & 3) << 2);
        !           131: 
        !           132:        /*
        !           133:         * Program memory offset in bank.
        !           134:         */
        !           135:        outb( port, ((int) paddr) >> 0 );
        !           136:        outb( port, ((int) paddr) >> 8 );
        !           137: 
        !           138:        port++;
        !           139:        if ( chan >= 4 )
        !           140:                port++;
        !           141: 
        !           142:        /*
        !           143:         * Program transfer count.
        !           144:         */
        !           145:        outb( port, count >> 0 );
        !           146:        outb( port, count >> 8 );
        !           147: 
        !           148:        spl(s);
        !           149:        return (1);
        !           150: }
        !           151: 
        !           152: /*
        !           153:  * dmago( chan ) - initiate dma transfer
        !           154:  */
        !           155: dmago( chan )
        !           156: register int chan;
        !           157: {
        !           158:        /*
        !           159:         * Enable dma transfers.
        !           160:         */
        !           161:        if ( chan < 4 )
        !           162:                outb( DMA  + (SETMASK * 1), (chan & 3) | MASKOFF );
        !           163:        else
        !           164:                outb( SDMA + (SETMASK * 2), (chan & 3) | MASKOFF );
        !           165: }
        !           166: 
        !           167: /*
        !           168:  * dmaoff( chan ) - turn dma channel off, return residual count
        !           169:  */
        !           170: dmaoff( chan )
        !           171: register int chan;
        !           172: {
        !           173:        register int port;
        !           174:        register int count;
        !           175:        int s;
        !           176: 
        !           177:        /*
        !           178:         * Disable DMA transfers.
        !           179:         * Obtain the -1 based residual count.
        !           180:         */
        !           181:        s = sphi();
        !           182:        if ( chan < 4 ) {
        !           183:                outb(  DMA + (SETMASK * 1), (chan & 3) | MASKON );
        !           184:                port = DMA + ((chan & 3) << 1) + 1;
        !           185:        }
        !           186:        else {
        !           187:                outb(  SDMA + (SETMASK * 2), (chan & 3) | MASKON );
        !           188:                port = SDMA + ((chan & 3) << 2) + 2;
        !           189:        }
        !           190:        count  = inb(port);
        !           191:        count += inb(port) << 8;
        !           192:        spl( s );
        !           193: 
        !           194:        /*
        !           195:         * Convert residual from -1 based to 0 based.
        !           196:         */
        !           197:        count++;
        !           198: 
        !           199:        /*
        !           200:         * Convert residual from word based to byte based.
        !           201:         */
        !           202:        if ( chan >= 5 )
        !           203:                count <<= 1;
        !           204: 
        !           205:        /*
        !           206:         * Return residual count in bytes.
        !           207:         */
        !           208:        return count;
        !           209: }

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