sys/arch/sun3/dev/btreg.h

   1 /*      $NetBSD: btreg.h,v 1.1.68.3 2004/09/21 13:23:19 skrll Exp $ */
   2
   3 /*
   4  * Copyright (c) 1993
   5  *      The Regents of the University of California.  All rights reserved.
   6  *
   7  * This software was developed by the Computer Systems Engineering group
   8  * at Lawrence Berkeley Laboratory under DARPA contract BG 91-66 and
   9  * contributed to Berkeley.
  10  *
  11  * All advertising materials mentioning features or use of this software
  12  * must display the following acknowledgement:
  13  *      This product includes software developed by the University of
  14  *      California, Lawrence Berkeley Laboratory.
  15  *
  16  * Redistribution and use in source and binary forms, with or without
  17  * modification, are permitted provided that the following conditions
  18  * are met:
  19  * 1. Redistributions of source code must retain the above copyright
  20  *    notice, this list of conditions and the following disclaimer.
  21  * 2. Redistributions in binary form must reproduce the above copyright
  22  *    notice, this list of conditions and the following disclaimer in the
  23  *    documentation and/or other materials provided with the distribution.
  24  * 3. Neither the name of the University nor the names of its contributors
  25  *    may be used to endorse or promote products derived from this software
  26  *    without specific prior written permission.
  27  *
  28  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  29  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  30  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  31  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  32  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  33  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  34  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  35  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  36  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  37  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  38  * SUCH DAMAGE.
  39  *
  40  *      @(#)btreg.h     8.2 (Berkeley) 1/21/94
  41  */
  42
  43 /*
  44  * Several Sun color frame buffers use some kind of Brooktree video
  45  * DAC (e.g., the Bt458, -- in any case, Brooktree make the only
  46  * decent color frame buffer chips).
  47  *
  48  * Color map control on these is a bit funky in a SPARCstation.
  49  * To update the color map one would normally do byte writes, but
  50  * the hardware takes longword writes.  Since there are three
  51  * registers for each color map entry (R, then G, then B), we have
  52  * to set color 1 with a write to address 0 (setting 0's R/G/B and
  53  * color 1's R) followed by a second write to address 1 (setting
  54  * color 1's G/B and color 2's R/G).  Software must therefore keep
  55  * a copy of the current map.
  56  *
  57  * The colormap address register increments automatically, so the
  58  * above write is done as:
  59  *
  60  *      bt->bt_addr = 0;
  61  *      bt->bt_cmap = R0G0B0R1;
  62  *      bt->bt_cmap = G1B1R2G2;
  63  *      ...
  64  *
  65  * Yow!
  66  *
  67  * Bonus complication: on the cg6, only the top 8 bits of each 32 bit
  68  * register matter, even though the cg3 takes all the bits from all
  69  * bytes written to it.
  70  */
  71 struct bt_regs {
  72         u_int   bt_addr;                /* map address register */
  73         u_int   bt_cmap;                /* colormap data register */
  74         u_int   bt_ctrl;                /* control register */
  75         u_int   bt_omap;                /* overlay (cursor) map register */
  76 };