summaryrefslogtreecommitdiff
diff options
context:
space:
mode:
-rw-r--r--src/pc80/i8259.c44
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 :-).
+*/
+