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Annotation of coherent/d/PS2_KERNEL/io.386/dmareq.c, revision 1.1

1.1     ! root        1: /* $Header: /kernel/kersrc/io.386/RCS/dmareq.c,v 1.2 92/08/04 12:52:39 bin Exp Locker: bin $ */
        !             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        !            12:  *     An unpublished work by Mark Williams Company, Chicago.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: /*
        !            17:  * Like ioreq, but guarantee that no DMA straddle occurs.
        !            18:  * And assume we are called by fl.c, xt.c, dv.c or someone
        !            19:  * else who obeys the parameter rules that they do.
        !            20:  *
        !            21:  * $Log:       dmareq.c,v $
        !            22:  * Revision 1.2  92/08/04  12:52:39  bin
        !            23:  * update for ker59
        !            24:  * 
        !            25:  * Revision 1.2  92/01/06  12:26:52  hal
        !            26:  * Compile with cc.mwc.
        !            27:  * 
        !            28:  * Revision 2.1        88/09/03  13:03:47      src
        !            29:  * *** empty log message ***
        !            30:  * 
        !            31:  * Revision 1.1        88/03/24  17:04:28      src
        !            32:  * Initial revision
        !            33:  * 
        !            34:  * 87/11/25    Allan Cornish           /usr/src/sys/i8086/drv/dmareq.c
        !            35:  * vaddr_t bp->b_vaddr --> faddr_t bp->b_faddr.
        !            36:  *
        !            37:  * 87/01/05    Allan Cornish           /usr/src/sys/i8086/drv/dmareq.c
        !            38:  * dmareq() now wakes &stimer only if the swap timer is active.
        !            39:  */
        !            40: #include <sys/coherent.h>
        !            41: #include <sys/buf.h>
        !            42: #include <sys/con.h>
        !            43: #include <errno.h>
        !            44: #include <sys/io.h>
        !            45: #include <sys/proc.h>
        !            46: #include <sys/sched.h>
        !            47: #include <sys/seg.h>
        !            48: #include <sys/stat.h>
        !            49: #include <sys/dmac.h>
        !            50: 
        !            51: dmareq(bp, iop, dev, req)
        !            52: register BUF *bp;
        !            53: register IO *iop;
        !            54: dev_t dev;
        !            55: {
        !            56:        register int to_read;
        !            57:        register SEG *sp;
        !            58:        register CON *cp;
        !            59:        dold_t dold;
        !            60:        long next_block;        /* Next block to be read.  */
        !            61:        paddr_t last;           /* Address of last byte we will read.  */
        !            62:        paddr_t next_seg;       /* Beginning of next dma segment.  */
        !            63:        BUF *tbp;
        !            64: 
        !            65:        if ((cp=drvmap(dev, &dold)) == NULL)
        !            66:                return;
        !            67:        lock(bp->b_gate);
        !            68:        drest(dold);
        !            69:        if (blocko(iop->io_seek) != 0) {
        !            70:                u.u_error = EIO;
        !            71:                goto out;
        !            72:        }
        !            73:        if ((sp=iomapvp(iop, bp)) == NULL) {
        !            74:                u.u_error = EIO;
        !            75:                goto out;
        !            76:        }
        !            77:        bp->b_dev = dev;
        !            78:        bp->b_flag = 0;
        !            79:        sp->s_lrefc++;
        !            80:        /*
        !            81:         * The dma address is 20 bits; 16 bit offset counter from a 4 bit
        !            82:         * base segment.  Since io_ioc is limited to 32Kb positive, we
        !            83:         * have at most two raw transfers separated by a block which
        !            84:         * straddles the segment boundary.
        !            85:         * Life would be simpler if we assumed io_ioc % BSIZE, but
        !            86:         * flioctl comes through here with it's short format buffer.
        !            87:         */
        !            88:        while (iop->io_ioc > 0 && (bp->b_flag&BFERR) == 0) {
        !            89:                /*
        !            90:                 * If the first and last bytes to be read are on different
        !            91:                 * dma segments, we have a stradle, and must read a fraction
        !            92:                 * of the entire animal.
        !            93:                 *
        !            94:                 * I don't understand why a fractional block at the
        !            95:                 * top of a segment is not read.
        !            96:                 */
        !            97:                last = bp->b_paddr+iop->io_ioc-1;
        !            98:                if (dmaseg(last) != dmaseg(bp->b_paddr)) {
        !            99:                        /*
        !           100:                         * We have a straddle--read at most to the end
        !           101:                         * of the next segment.
        !           102:                         */
        !           103:                        next_seg = dmaseg(bp->b_paddr + DMASEG_SIZE);
        !           104:                        to_read = (next_seg - bp->b_paddr) & ~((long)BSIZE-1);
        !           105:                } else {
        !           106:                        /* No straddle.  */
        !           107:                        to_read = iop->io_ioc;
        !           108:                }
        !           109:                next_block = blockn(iop->io_seek);
        !           110:                if (to_read == 0) {
        !           111:                        /* Straddle block */
        !           112:                        tbp = bp;               /* Save the raw buffer */
        !           113:                        to_read = BSIZE;
        !           114:                        if (to_read > iop->io_ioc)
        !           115:                                to_read = iop->io_ioc;
        !           116:                        bp = bclaim(dev, next_block);
        !           117:                        bp->b_count = to_read;
        !           118:                        bp->b_req = req;
        !           119:                        if (req != BREAD)
        !           120:                                ioread(iop, bp->b_vaddr, to_read);
        !           121:                        dmabuf(bp, dev);
        !           122:                        if ((bp->b_flag&BFERR) == 0) {
        !           123:                                if (req == BREAD)
        !           124:                                        iowrite(iop, bp->b_vaddr, to_read);
        !           125:                        } else {
        !           126:                                tbp->b_flag = bp->b_flag;
        !           127:                                tbp->b_err = bp->b_err;
        !           128:                                if (req != BREAD)
        !           129:                                        iop->io_ioc += bp->b_resid;
        !           130:                        }
        !           131:                        bp->b_flag |= BFERR;
        !           132:                        brelease(bp);
        !           133:                        bp = tbp;               /* Reclaim raw buffer */
        !           134:                } else {
        !           135:                        /* Raw transfer */
        !           136:                        bp->b_count = to_read;
        !           137:                        bp->b_req = req;
        !           138:                        bp->b_bno = next_block;
        !           139:                        dmabuf(bp, dev);
        !           140:                        if ((bp->b_flag&BFERR) != 0)
        !           141:                                to_read -= bp->b_resid;
        !           142:                        iop->io_ioc -= to_read;    /* cookedio do these */
        !           143:                        iop->io.pbase += to_read;  /* for everyone */
        !           144:                }
        !           145:                bp->b_vaddr += to_read;
        !           146:                bp->b_paddr  += to_read;
        !           147:                iop->io_seek += to_read;
        !           148:                /* And continue for the next chunk */
        !           149:        }
        !           150:        sp->s_lrefc--;
        !           151:        if ( stimer.t_last != 0 )
        !           152:                wakeup((char *)&stimer);
        !           153:        if ((bp->b_flag&BFERR) != 0 && (u.u_error = bp->b_err) == 0)
        !           154:                u.u_error = EIO;
        !           155: out:
        !           156:        unlock(bp->b_gate);
        !           157: }
        !           158: 
        !           159: static
        !           160: dmabuf(bp, dev)
        !           161: register BUF *bp;
        !           162: dev_t dev;
        !           163: {
        !           164:        register int s;
        !           165:        bp->b_flag = BFRAW|BFBLK|BFIOC|BFNTP;
        !           166:        s = sphi();
        !           167:        dblock(dev, bp);
        !           168:        while ((bp->b_flag&BFNTP) != 0)
        !           169:                sleep((char *)bp, CVBLKIO, IVBLKIO, SVBLKIO);
        !           170:        spl(s);
        !           171: }

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