1/* $NetBSD: vga_common.c,v 1.10 2008/04/08 12:07:27 cegger 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@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/cdefs.h>
31__KERNEL_RCSID(0, "$NetBSD: vga_common.c,v 1.10 2008/04/08 12:07:27 cegger Exp $");
32
33#include <sys/param.h>
34#include <sys/device.h>
35#include <sys/bus.h>
36
37#include <dev/ic/mc6845reg.h>
38#include <dev/ic/pcdisplayvar.h>
39#include <dev/ic/vgareg.h>
40#include <dev/ic/vgavar.h>
41
42/*
43 * The following functions implement back-end configuration grabbing
44 * and attachment.
45 */
46int
47vga_common_probe(bus_space_tag_t iot, bus_space_tag_t memt)
48{
49	bus_space_handle_t ioh_vga, ioh_6845, memh;
50	u_int8_t regval;
51	u_int16_t vgadata;
52	int gotio_vga, gotio_6845, gotmem, mono, rv;
53	int dispoffset;
54
55	gotio_vga = gotio_6845 = gotmem = rv = 0;
56
57	if (bus_space_map(iot, 0x3c0, 0x10, 0, &ioh_vga))
58		goto bad;
59	gotio_vga = 1;
60
61	/* read "misc output register" */
62	regval = bus_space_read_1(iot, ioh_vga, VGA_MISC_DATAR);
63	mono = !(regval & 1);
64
65	if (bus_space_map(iot, (mono ? 0x3b0 : 0x3d0), 0x10, 0, &ioh_6845))
66		goto bad;
67	gotio_6845 = 1;
68
69	if (bus_space_map(memt, 0xa0000, 0x20000, 0, &memh))
70		goto bad;
71	gotmem = 1;
72
73	dispoffset = (mono ? 0x10000 : 0x18000);
74
75	vgadata = bus_space_read_2(memt, memh, dispoffset);
76	bus_space_write_2(memt, memh, dispoffset, 0xa55a);
77	if (bus_space_read_2(memt, memh, dispoffset) != 0xa55a)
78		goto bad;
79	bus_space_write_2(memt, memh, dispoffset, vgadata);
80
81	/*
82	 * check if this is really a VGA
83	 * (try to write "Color Select" register as XFree86 does)
84	 * XXX check before if at least EGA?
85	 */
86	/* reset state */
87	(void) bus_space_read_1(iot, ioh_6845, 10);
88	bus_space_write_1(iot, ioh_vga, VGA_ATC_INDEX,
89	    20 | 0x20); /* colselect | enable */
90	regval = bus_space_read_1(iot, ioh_vga, VGA_ATC_DATAR);
91	/* toggle the implemented bits */
92	bus_space_write_1(iot, ioh_vga, VGA_ATC_DATAW, regval ^ 0x0f);
93	bus_space_write_1(iot, ioh_vga, VGA_ATC_INDEX, 20 | 0x20);
94	/* read back */
95	if (bus_space_read_1(iot, ioh_vga, VGA_ATC_DATAR) != (regval ^ 0x0f))
96		goto bad;
97	/* restore contents */
98	bus_space_write_1(iot, ioh_vga, VGA_ATC_DATAW, regval);
99
100	rv = 1;
101bad:
102	if (gotio_vga)
103		bus_space_unmap(iot, ioh_vga, 0x10);
104	if (gotio_6845)
105		bus_space_unmap(iot, ioh_6845, 0x10);
106	if (gotmem)
107		bus_space_unmap(memt, memh, 0x20000);
108
109	return (rv);
110}
111