biosacpi.c revision 114246 
1/*-
2 * Copyright (c) 2001 Michael Smith <msmith@freebsd.org>
3 * All rights reserved.
4 *
5 * Redistribution and use in source and binary forms, with or without
6 * modification, are permitted provided that the following conditions
7 * are met:
8 * 1. Redistributions of source code must retain the above copyright
9 *    notice, this list of conditions and the following disclaimer.
10 * 2. Redistributions in binary form must reproduce the above copyright
11 *    notice, this list of conditions and the following disclaimer in the
12 *    documentation and/or other materials provided with the distribution.
13 *
14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
15 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
17 * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
18 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
19 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
20 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
22 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
23 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
24 * SUCH DAMAGE.
25 *
26 * $FreeBSD: head/sys/boot/i386/libi386/biosacpi.c 114246 2003-04-29 18:50:34Z njl $
27 */
28
29#include <stand.h>
30#include <machine/stdarg.h>
31#include <bootstrap.h>
32
33#include "acfreebsd.h"
34#define ACPI_SYSTEM_XFACE
35#include "actypes.h"
36#include "actbl.h"
37
38/*
39 * Detect ACPI and export information about the APCI BIOS into the
40 * environment.
41 */
42
43static RSDP_DESCRIPTOR	*biosacpi_find_rsdp(void);
44static RSDP_DESCRIPTOR	*biosacpi_search_rsdp(char *base, int length);
45
46#define RSDP_CHECKSUM_LENGTH 20
47
48void
49biosacpi_detect(void)
50{
51    RSDP_DESCRIPTOR	*rsdp;
52    char		buf[16];
53    int			revision;
54
55    /* XXX check the BIOS datestamp */
56
57    /* locate and validate the RSDP */
58    if ((rsdp = biosacpi_find_rsdp()) == NULL)
59	return;
60
61    /* export values from the RSDP */
62    revision = rsdp->Revision;
63    if (revision == 0)
64	revision = 1;
65    sprintf(buf, "%d", revision);
66    setenv("hint.acpi.0.revision", buf, 1);
67    sprintf(buf, "%6s", rsdp->OemId);
68    setenv("hint.acpi.0.oem", buf, 1);
69    sprintf(buf, "0x%08x", rsdp->RsdtPhysicalAddress);
70    setenv("hint.acpi.0.rsdt", buf, 1);
71    if (revision >= 2) {
72	/* XXX extended checksum? */
73	sprintf(buf, "0x%016llx", rsdp->XsdtPhysicalAddress);
74	setenv("hint.acpi.0.xsdt", buf, 1);
75	sprintf(buf, "%d", rsdp->Length);
76	setenv("hint.acpi.0.xsdt_length", buf, 1);
77    }
78    /* XXX other tables? */
79
80    setenv("acpi_load", "YES", 1);
81}
82
83/*
84 * Find the RSDP in low memory.
85 */
86static RSDP_DESCRIPTOR *
87biosacpi_find_rsdp(void)
88{
89    RSDP_DESCRIPTOR	*rsdp;
90
91    /* search the EBDA */
92    if ((rsdp = biosacpi_search_rsdp((char *)0, 0x400)) != NULL)
93	return(rsdp);
94
95    /* search the BIOS space */
96    if ((rsdp = biosacpi_search_rsdp((char *)0xe0000, 0x20000)) != NULL)
97	return(rsdp);
98
99    return(NULL);
100}
101
102static RSDP_DESCRIPTOR *
103biosacpi_search_rsdp(char *base, int length)
104{
105    RSDP_DESCRIPTOR	*rsdp;
106    u_int8_t		*cp, sum;
107    int			ofs, idx;
108
109    /* search on 16-byte boundaries */
110    for (ofs = 0; ofs < length; ofs += 16) {
111	rsdp = (RSDP_DESCRIPTOR *)(base + ofs);
112
113	/* compare signature, validate checksum */
114	if (!strncmp(rsdp->Signature, RSDP_SIG, strlen(RSDP_SIG))) {
115	    cp = (u_int8_t *)rsdp;
116	    sum = 0;
117	    for (idx = 0; idx < RSDP_CHECKSUM_LENGTH; idx++)
118		sum += *(cp + idx);
119	    if (sum != 0) {
120		printf("acpi: bad RSDP checksum (%d)\n", sum);
121		continue;
122	    }
123	    return(rsdp);
124	}
125    }
126    return(NULL);
127}
128