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Annotation of coherent/b/STREAMS/io.386/dmareq.c, revision 1.1

1.1     ! root        1: /* dmareq.c */
        !             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 4.1.0
        !            11:  *     Copyright (c) 1993.
        !            12:  *     An unpublished work by Mark Williams Company, Chicago.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:  */
        !            22: #include <sys/coherent.h>
        !            23: #include <sys/buf.h>
        !            24: #include <sys/con.h>
        !            25: #include <sys/errno.h>
        !            26: #include <sys/io.h>
        !            27: #include <sys/proc.h>
        !            28: #include <sys/sched.h>
        !            29: #include <sys/seg.h>
        !            30: #include <sys/stat.h>
        !            31: #include <sys/dmac.h>
        !            32: 
        !            33: /*
        !            34:  * NIGEL: Why the hell is this routine not in bio.c? It would be a whole lot
        !            35:  * nicer if it was. "dold_t" is obsolete, by the way, and all instances of it
        !            36:  * will disappear from "bio.c" sometime. I should merge this in as well then.
        !            37:  */
        !            38: typedef        unsigned char           dold_t;
        !            39: 
        !            40: dmareq(bp, iop, dev, req)
        !            41: register BUF *bp;
        !            42: register IO *iop;
        !            43: dev_t dev;
        !            44: {
        !            45:        register int to_read;
        !            46:        register SEG *sp;
        !            47:        register CON *cp;
        !            48:        dold_t dold;
        !            49:        long next_block;        /* Next block to be read.  */
        !            50:        paddr_t last;           /* Address of last byte we will read.  */
        !            51:        paddr_t next_seg;       /* Beginning of next dma segment.  */
        !            52:        BUF *tbp;
        !            53: 
        !            54:        if ((cp = drvmap (dev)) == NULL)
        !            55:                return;
        !            56:        lock (bp->b_gate);
        !            57: 
        !            58:        if (blocko(iop->io_seek)) {
        !            59:                SET_U_ERROR(EIO, "dmareq() seek");
        !            60:                goto out;
        !            61:        }
        !            62:        if ((sp=iomapvp(iop, bp)) == NULL) {
        !            63:                SET_U_ERROR(EIO, "dmareq() iomapvp");
        !            64:                goto out;
        !            65:        }
        !            66:        bp->b_dev = dev;
        !            67:        bp->b_flag = 0;
        !            68:        sp->s_lrefc++;
        !            69: 
        !            70:        /*
        !            71:         * The dma address is 20 bits; 16 bit offset counter from a 4 bit
        !            72:         * base segment.  Since io_ioc is limited to 32Kb positive, we
        !            73:         * have at most two raw transfers separated by a block which
        !            74:         * straddles the segment boundary.
        !            75:         * Life would be simpler if we assumed io_ioc % BSIZE, but
        !            76:         * flioctl comes through here with its short format buffer.
        !            77:         */
        !            78:        while (iop->io_ioc > 0 && (bp->b_flag&BFERR) == 0) {
        !            79:                /*
        !            80:                 * If the first and last bytes to be read are on different
        !            81:                 * dma segments, we have a stradle, and must read a fraction
        !            82:                 * of the entire animal.
        !            83:                 *
        !            84:                 * I don't understand why a fractional block at the
        !            85:                 * top of a segment is not read.
        !            86:                 */
        !            87:                last = bp->b_paddr+iop->io_ioc-1;
        !            88:                if (dmaseg(last) != dmaseg(bp->b_paddr)) {
        !            89:                        /*
        !            90:                         * We have a straddle--read at most to the end
        !            91:                         * of the next segment.
        !            92:                         */
        !            93:                        next_seg = dmaseg(bp->b_paddr + DMASEG_SIZE);
        !            94:                        to_read = (next_seg - bp->b_paddr) & ~((long)BSIZE-1);
        !            95:                } else {
        !            96:                        /* No straddle.  */
        !            97:                        to_read = iop->io_ioc;
        !            98:                }
        !            99:                next_block = blockn(iop->io_seek);
        !           100:                if (to_read == 0) {
        !           101:                        /* Straddle block */
        !           102:                        tbp = bp;               /* Save the raw buffer */
        !           103:                        to_read = BSIZE;
        !           104:                        if (to_read > iop->io_ioc)
        !           105:                                to_read = iop->io_ioc;
        !           106:                        bp = bclaim (dev, next_block, BUF_SYNC);
        !           107:                        bp->b_count = to_read;
        !           108:                        bp->b_req = req;
        !           109:                        if (req != BREAD)
        !           110:                                ioread(iop, bp->b_vaddr, to_read);
        !           111:                        dmabuf(bp, dev);
        !           112:                        if ((bp->b_flag&BFERR) == 0) {
        !           113:                                if (req == BREAD)
        !           114:                                        iowrite(iop, bp->b_vaddr, to_read);
        !           115:                        } else {
        !           116:                                tbp->b_flag = bp->b_flag;
        !           117:                                tbp->b_err = bp->b_err;
        !           118:                                if (req != BREAD)
        !           119:                                        iop->io_ioc += bp->b_resid;
        !           120:                        }
        !           121:                        bp->b_flag |= BFERR;
        !           122:                        brelease(bp);
        !           123:                        bp = tbp;               /* Reclaim raw buffer */
        !           124:                } else {
        !           125:                        /* Raw transfer */
        !           126:                        bp->b_count = to_read;
        !           127:                        bp->b_req = req;
        !           128:                        bp->b_bno = next_block;
        !           129:                        dmabuf(bp, dev);
        !           130:                        if (bp->b_flag & BFERR)
        !           131:                                to_read -= bp->b_resid;
        !           132:                        iop->io_ioc -= to_read;    /* cookedio do these */
        !           133:                        iop->io.pbase += to_read;  /* for everyone */
        !           134:                }
        !           135:                bp->b_vaddr += to_read;
        !           136:                bp->b_paddr  += to_read;
        !           137:                iop->io_seek += to_read;
        !           138:                /* And continue for the next chunk */
        !           139:        }
        !           140:        sp->s_lrefc--;
        !           141:        if ( stimer.t_last != 0 )
        !           142:                wakeup((char *)&stimer);
        !           143:        if ((bp->b_flag&BFERR) && (u.u_error = bp->b_err) == 0)
        !           144:                SET_U_ERROR(EIO, "dmareq() BFERR");
        !           145: out:
        !           146:        unlock(bp->b_gate);
        !           147: }
        !           148: 
        !           149: /*
        !           150:  * dmabuf()
        !           151:  *
        !           152:  * Hand off a buf request to the block handler and go to sleep.
        !           153:  */
        !           154: static
        !           155: dmabuf(bp, dev)
        !           156: register BUF *bp;
        !           157: dev_t dev;
        !           158: {
        !           159:        register int s;
        !           160: 
        !           161:        bp->b_flag = BFRAW|BFBLK|BFIOC|BFNTP;
        !           162:        s = sphi();
        !           163:        dblock(dev, bp);
        !           164:        while (bp->b_flag&BFNTP)
        !           165:                x_sleep((char *)bp, pridisk, slpriNoSig, "dmabuf");
        !           166:        spl(s);
        !           167: }

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