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| -rw-r--r-- | src/pc80/i8259.c | 44 |
1 files changed, 44 insertions, 0 deletions
diff --git a/src/pc80/i8259.c b/src/pc80/i8259.c new file mode 100644 index 0000000000..cd3ef0bbcc --- /dev/null +++ b/src/pc80/i8259.c @@ -0,0 +1,44 @@ + + + +#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 :-). +*/ + |