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vga_common.c revision 1.3 
      1 /* $NetBSD: vga_common.c,v 1.3 2003/01/27 15:16:11 tsutsui Exp $ */
      2 
      3 /*
      4  * Copyright (c) 1995, 1996 Carnegie-Mellon University.
      5  * All rights reserved.
      6  *
      7  * Author: Chris G. Demetriou
      8  *
      9  * Permission to use, copy, modify and distribute this software and
     10  * its documentation is hereby granted, provided that both the copyright
     11  * notice and this permission notice appear in all copies of the
     12  * software, derivative works or modified versions, and any portions
     13  * thereof, and that both notices appear in supporting documentation.
     14  *
     15  * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
     16  * CONDITION.  CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND
     17  * FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
     18  *
     19  * Carnegie Mellon requests users of this software to return to
     20  *
     21  *  Software Distribution Coordinator  or  Software.Distribution (at) CS.CMU.EDU
     22  *  School of Computer Science
     23  *  Carnegie Mellon University
     24  *  Pittsburgh PA 15213-3890
     25  *
     26  * any improvements or extensions that they make and grant Carnegie the
     27  * rights to redistribute these changes.
     28  */
     29 
     30 #include <sys/param.h>
     31 #include <sys/device.h>
     32 #include <machine/bus.h>
     33 
     34 #include <dev/ic/mc6845reg.h>
     35 #include <dev/ic/pcdisplayvar.h>
     36 #include <dev/ic/vgareg.h>
     37 #include <dev/ic/vgavar.h>
     38 
     39 /*
     40  * The following functions implement back-end configuration grabbing
     41  * and attachment.
     42  */
     43 int
     44 vga_common_probe(bus_space_tag_t iot, bus_space_tag_t memt)
     45 {
     46 	bus_space_handle_t ioh_vga, ioh_6845, memh;
     47 	u_int8_t regval;
     48 	u_int16_t vgadata;
     49 	int gotio_vga, gotio_6845, gotmem, mono, rv;
     50 	int dispoffset;
     51 
     52 	gotio_vga = gotio_6845 = gotmem = rv = 0;
     53 
     54 	if (bus_space_map(iot, 0x3c0, 0x10, 0, &ioh_vga))
     55 		goto bad;
     56 	gotio_vga = 1;
     57 
     58 	/* read "misc output register" */
     59 	regval = bus_space_read_1(iot, ioh_vga, VGA_MISC_DATAR);
     60 	mono = !(regval & 1);
     61 
     62 	if (bus_space_map(iot, (mono ? 0x3b0 : 0x3d0), 0x10, 0, &ioh_6845))
     63 		goto bad;
     64 	gotio_6845 = 1;
     65 
     66 	if (bus_space_map(memt, 0xa0000, 0x20000, 0, &memh))
     67 		goto bad;
     68 	gotmem = 1;
     69 
     70 	dispoffset = (mono ? 0x10000 : 0x18000);
     71 
     72 	vgadata = bus_space_read_2(memt, memh, dispoffset);
     73 	bus_space_write_2(memt, memh, dispoffset, 0xa55a);
     74 	if (bus_space_read_2(memt, memh, dispoffset) != 0xa55a)
     75 		goto bad;
     76 	bus_space_write_2(memt, memh, dispoffset, vgadata);
     77 
     78 	/*
     79 	 * check if this is really a VGA
     80 	 * (try to write "Color Select" register as XFree86 does)
     81 	 * XXX check before if at least EGA?
     82 	 */
     83 	/* reset state */
     84 	(void) bus_space_read_1(iot, ioh_6845, 10);
     85 	bus_space_write_1(iot, ioh_vga, VGA_ATC_INDEX,
     86 	    20 | 0x20); /* colselect | enable */
     87 	regval = bus_space_read_1(iot, ioh_vga, VGA_ATC_DATAR);
     88 	/* toggle the implemented bits */
     89 	bus_space_write_1(iot, ioh_vga, VGA_ATC_DATAW, regval ^ 0x0f);
     90 	bus_space_write_1(iot, ioh_vga, VGA_ATC_INDEX, 20 | 0x20);
     91 	/* read back */
     92 	if (bus_space_read_1(iot, ioh_vga, VGA_ATC_DATAR) != (regval ^ 0x0f))
     93 		goto bad;
     94 	/* restore contents */
     95 	bus_space_write_1(iot, ioh_vga, VGA_ATC_DATAW, regval);
     96 
     97 	rv = 1;
     98 bad:
     99 	if (gotio_vga)
    100 		bus_space_unmap(iot, ioh_vga, 0x10);
    101 	if (gotio_6845)
    102 		bus_space_unmap(iot, ioh_6845, 0x10);
    103 	if (gotmem)
    104 		bus_space_unmap(memt, memh, 0x20000);
    105 
    106 	return (rv);
    107 }
    108