ref: 9f76a7f6819ac04552b4fb6588156f3e4089d1d7
dir: /os/pc/apm.c/
/*
* Interface to Advanced Power Management 1.2 BIOS
*
* This is, in many ways, a giant hack, and when things settle down
* a bit and standardize, hopefully we can write a driver that deals
* more directly with the hardware and thus might be a bit cleaner.
*
* ACPI might be the answer, but at the moment this is simpler
* and more widespread.
*/
#include "u.h"
#include "../port/lib.h"
#include "mem.h"
#include "dat.h"
#include "fns.h"
#include "io.h"
#include "ureg.h"
extern int apmfarcall(ushort, ulong, Ureg*); /* apmjump.s */
static int
getreg(ulong *reg, ISAConf *isa, char *name)
{
int i;
int nl;
nl = strlen(name);
for(i=0; i<isa->nopt; i++){
if(cistrncmp(isa->opt[i], name, nl)==0 && isa->opt[i][nl] == '='){
*reg = strtoul(isa->opt[i]+nl+1, nil, 16);
return 0;
}
}
return -1;
}
/*
* Segment descriptors look like this.
*
* d1: [base 31:24] [gran] [is32bit] [0] [unused] [limit 19:16]
[present] [privlev] [type 3:0] [base 23:16]
* d0: [base 15:00] [limit 15:00]
*
* gran is 0 for 1-byte granularity, 1 for 4k granularity
* type is 0 for system segment, 1 for code/data.
*
* clearly we know way too much about the memory unit.
* however, knowing this much about the memory unit
* means that the memory unit need not know anything
* about us.
*
* what a crock.
*/
static void
setgdt(int sel, ulong base, ulong limit, int flag)
{
if(sel < 0 || sel >= NGDT)
panic("setgdt");
base = (ulong)KADDR(base);
m->gdt[sel].d0 = (base<<16) | (limit&0xFFFF);
m->gdt[sel].d1 = (base&0xFF000000) | (limit&0x000F0000) |
((base>>16)&0xFF) | SEGP | SEGPL(0) | flag;
}
static ulong ax, cx, dx, di, ebx, esi;
static Ureg apmu;
static long
apmread(Chan*, void *a, long n, vlong off)
{
if(off < 0)
error("badarg");
if(n+off > sizeof apmu)
n = sizeof apmu - off;
if(n <= 0)
return 0;
memmove(a, (char*)&apmu+off, n);
return n;
}
static long
apmwrite(Chan*, void *a, long n, vlong off)
{
int s;
if(off || n != sizeof apmu)
error("write a Ureg");
memmove(&apmu, a, sizeof apmu);
s = splhi();
apmfarcall(APMCSEL, ebx, &apmu);
splx(s);
return n;
}
void
apmlink(void)
{
ISAConf isa;
char *s;
if(isaconfig("apm", 0, &isa) == 0)
return;
/*
* APM info passed from boot loader.
* Now we need to set up the GDT entries for APM.
*
* AX = 32-bit code segment base address
* EBX = 32-bit code segment offset
* CX = 16-bit code segment base address
* DX = 32-bit data segment base address
* ESI = <16-bit code segment length> <32-bit code segment length> (hi then lo)
* DI = 32-bit data segment length
*/
if(getreg(&ax, &isa, s="ax") < 0
|| getreg(&ebx, &isa, s="ebx") < 0
|| getreg(&cx, &isa, s="cx") < 0
|| getreg(&dx, &isa, s="dx") < 0
|| getreg(&esi, &isa, s="esi") < 0
|| getreg(&di, &isa, s="di") < 0){
print("apm: missing register %s\n", s);
return;
}
/*
* The NEC Versa SX bios does not report the correct 16-bit code
* segment length when loaded directly from mbr -> 9load (as compared
* with going through ld.com). We'll make both code segments 64k-1 bytes.
*/
esi = 0xFFFFFFFF;
/*
* We are required by the BIOS to set up three consecutive segments,
* one for the APM 32-bit code, one for the APM 16-bit code, and
* one for the APM data. The BIOS handler uses the code segment it
* get called with to determine the other two segment selector.
*/
setgdt(APMCSEG, ax<<4, ((esi&0xFFFF)-1)&0xFFFF, SEGEXEC|SEGR|SEGD);
setgdt(APMCSEG16, cx<<4, ((esi>>16)-1)&0xFFFF, SEGEXEC|SEGR);
setgdt(APMDSEG, dx<<4, (di-1)&0xFFFF, SEGDATA|SEGW|SEGD);
addarchfile("apm", 0660, apmread, apmwrite);
print("apm0: configured cbase %.8lux off %.8lux\n", ax<<4, ebx);
return;
}