1 /*
2 * Interface to Advanced Power Management 1.2 BIOS
3 *
4 * This is, in many ways, a giant hack, and when things settle down
5 * a bit and standardize, hopefully we can write a driver that deals
6 * more directly with the hardware and thus might be a bit cleaner.
7 *
8 * ACPI might be the answer, but at the moment this is simpler
9 * and more widespread.
10 */
11
12 #include "u.h"
13 #include "../port/lib.h"
14 #include "mem.h"
15 #include "dat.h"
16 #include "fns.h"
17 #include "io.h"
18 #include "ureg.h"
19
20 extern int apmfarcall(ushort, ulong, Ureg*); /* apmjump.s */
21
22 static int
getreg(ulong * reg,ISAConf * isa,char * name)23 getreg(ulong *reg, ISAConf *isa, char *name)
24 {
25 int i;
26 int nl;
27
28 nl = strlen(name);
29 for(i=0; i<isa->nopt; i++){
30 if(cistrncmp(isa->opt[i], name, nl)==0 && isa->opt[i][nl] == '='){
31 *reg = strtoul(isa->opt[i]+nl+1, nil, 16);
32 return 0;
33 }
34 }
35 return -1;
36 }
37
38 /*
39 * Segment descriptors look like this.
40 *
41 * d1: [base 31:24] [gran] [is32bit] [0] [unused] [limit 19:16]
42 [present] [privlev] [type 3:0] [base 23:16]
43 * d0: [base 15:00] [limit 15:00]
44 *
45 * gran is 0 for 1-byte granularity, 1 for 4k granularity
46 * type is 0 for system segment, 1 for code/data.
47 *
48 * clearly we know way too much about the memory unit.
49 * however, knowing this much about the memory unit
50 * means that the memory unit need not know anything
51 * about us.
52 *
53 * what a crock.
54 */
55 static void
setgdt(int sel,ulong base,ulong limit,int flag)56 setgdt(int sel, ulong base, ulong limit, int flag)
57 {
58 if(sel < 0 || sel >= NGDT)
59 panic("setgdt");
60
61 base = (ulong)KADDR(base);
62 m->gdt[sel].d0 = (base<<16) | (limit&0xFFFF);
63 m->gdt[sel].d1 = (base&0xFF000000) | (limit&0x000F0000) |
64 ((base>>16)&0xFF) | SEGP | SEGPL(0) | flag;
65 }
66
67 static ulong ax, cx, dx, di, ebx, esi;
68 static Ureg apmu;
69 static long
apmread(Chan *,void * a,long n,vlong off)70 apmread(Chan*, void *a, long n, vlong off)
71 {
72 if(off < 0)
73 error("badarg");
74
75 if(n+off > sizeof apmu)
76 n = sizeof apmu - off;
77 if(n <= 0)
78 return 0;
79 memmove(a, (char*)&apmu+off, n);
80 return n;
81 }
82
83 static long
apmwrite(Chan *,void * a,long n,vlong off)84 apmwrite(Chan*, void *a, long n, vlong off)
85 {
86 int s;
87 if(off || n != sizeof apmu)
88 error("write a Ureg");
89
90 memmove(&apmu, a, sizeof apmu);
91 s = splhi();
92 apmfarcall(APMCSEL, ebx, &apmu);
93 splx(s);
94 return n;
95 }
96
97 void
apmlink(void)98 apmlink(void)
99 {
100 ISAConf isa;
101 char *s;
102
103 if(isaconfig("apm", 0, &isa) == 0)
104 return;
105
106 /* XXX use realmode() */
107
108 /*
109 * APM info passed from boot loader.
110 * Now we need to set up the GDT entries for APM.
111 *
112 * AX = 32-bit code segment base address
113 * EBX = 32-bit code segment offset
114 * CX = 16-bit code segment base address
115 * DX = 32-bit data segment base address
116 * ESI = <16-bit code segment length> <32-bit code segment length> (hi then lo)
117 * DI = 32-bit data segment length
118 */
119
120 if(getreg(&ax, &isa, s="ax") < 0
121 || getreg(&ebx, &isa, s="ebx") < 0
122 || getreg(&cx, &isa, s="cx") < 0
123 || getreg(&dx, &isa, s="dx") < 0
124 || getreg(&esi, &isa, s="esi") < 0
125 || getreg(&di, &isa, s="di") < 0){
126 print("apm: missing register %s\n", s);
127 return;
128 }
129
130 /*
131 * The NEC Versa SX bios does not report the correct 16-bit code
132 * segment length when loaded directly from mbr -> 9load (as compared
133 * with going through ld.com). We'll make both code segments 64k-1 bytes.
134 */
135 esi = 0xFFFFFFFF;
136
137 /*
138 * We are required by the BIOS to set up three consecutive segments,
139 * one for the APM 32-bit code, one for the APM 16-bit code, and
140 * one for the APM data. The BIOS handler uses the code segment it
141 * get called with to determine the other two segment selector.
142 */
143 setgdt(APMCSEG, ax<<4, ((esi&0xFFFF)-1)&0xFFFF, SEGEXEC|SEGR|SEGD);
144 setgdt(APMCSEG16, cx<<4, ((esi>>16)-1)&0xFFFF, SEGEXEC|SEGR);
145 setgdt(APMDSEG, dx<<4, (di-1)&0xFFFF, SEGDATA|SEGW|SEGD);
146
147 addarchfile("apm", 0660, apmread, apmwrite);
148
149 print("apm0: configured cbase %.8lux off %.8lux\n", ax<<4, ebx);
150
151 return;
152 }
153
154