1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
|
#include <arch/io.h>
/* code taken from:
!
! setup.S Copyright (C) 1991, 1992 Linus Torvalds
!
! setup.s is responsible for getting the system data from the BIOS,
! and putting them into the appropriate places in system memory.
! both setup.s and system has been loaded by the bootblock.
*/
/* we're getting screwed again and again by this problem of the 8259.
* so we're going to leave this lying around for inclusion into
* crt0.S on an as-needed basis.
! well, that went ok, I hope. Now we have to reprogram the interrupts :-(
! we put them right after the intel-reserved hardware interrupts, at
! int 0x20-0x2F. There they won't mess up anything. Sadly IBM really
! messed this up with the original PC, and they haven't been able to
! rectify it afterwards. Thus the bios puts interrupts at 0x08-0x0f,
! which is used for the internal hardware interrupts as well. We just
! have to reprogram the 8259's, and it isn't fun.
*/
void setup_i8259(void)
{
outb(0x11, 0x20); /*! initialization sequence to 8259A-1*/
outb(0x11, 0xA0); /*! and to 8259A-2*/
outb(0x20, 0x21); /*! start of hardware int's (0x20)*/
outb(0x28, 0xA1); /*! start of hardware int's 2 (0x28)*/
outb(0x04, 0x21); /*! 8259-1 is master*/
outb(0x02, 0xA1); /*! 8259-2 is slave*/
outb(0x01, 0x21); /*! 8086 mode for both*/
outb(0x01, 0xA1);
outb(0xFF, 0xA1); /*! mask off all interrupts for now*/
outb(0xFB, 0x21); /*! mask all irq's but irq2 which is cascaded*/
}
/*
* I like the way Linus says it:
! Well, that certainly wasn't fun :-(. Hopefully it works, and we don't
! need no steenking BIOS anyway (except for the initial loading :-).
*/
|
