9778b7b790
git-svn-id: http://svn.lfbs.rwth-aachen.de/svn/scc/trunk/MetalSVM@2 315a16e6-25f9-4109-90ae-ca3045a26c18
161 lines
4.6 KiB
C
161 lines
4.6 KiB
C
/*
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* Copyright 2010 Stefan Lankes, Chair for Operating Systems,
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* RWTH Aachen University
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*
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* This file is part of MetalSVM.
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*/
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#include <metalsvm/irq.h>
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#include <metalsvm/string.h>
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#include <asm/idt.h>
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#include <asm/isrs.h>
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/*
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* These are own ISRs that point to our special IRQ handler
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* instead of the regular 'fault_handler' function
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*/
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extern void irq0();
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extern void irq1();
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extern void irq2();
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extern void irq3();
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extern void irq4();
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extern void irq5();
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extern void irq6();
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extern void irq7();
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extern void irq8();
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extern void irq9();
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extern void irq10();
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extern void irq11();
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extern void irq12();
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extern void irq13();
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extern void irq14();
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extern void irq15();
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/*
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* This array is actually an array of function pointers. We use
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* this to handle custom IRQ handlers for a given IRQ
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*/
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static void *irq_routines[16] = { 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0 };
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/* This installs a custom IRQ handler for the given IRQ */
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void irq_install_handler(unsigned int irq, irq_handler_t handler)
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{
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irq_routines[irq] = handler;
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}
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/* This clears the handler for a given IRQ */
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void irq_uninstall_handler(unsigned int irq)
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{
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irq_routines[irq] = NULL;
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}
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/*
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* Normally, IRQs 0 to 7 are mapped to entries 8 to 15. This
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* is a problem in protected mode, because IDT entry 8 is a
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* Double Fault! Without remapping, every time IRQ0 fires,
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* you get a Double Fault Exception, which is NOT actually
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* what's happening. We send commands to the Programmable
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* Interrupt Controller (PICs - also called the 8259's) in
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* order to make IRQ0 to 15 be remapped to IDT entries 32 to
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* 47
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*/
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static void irq_remap(void)
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{
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outportb(0x20, 0x11);
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outportb(0xA0, 0x11);
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outportb(0x21, 0x20);
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outportb(0xA1, 0x28);
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outportb(0x21, 0x04);
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outportb(0xA1, 0x02);
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outportb(0x21, 0x01);
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outportb(0xA1, 0x01);
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outportb(0x21, 0x0);
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outportb(0xA1, 0x0);
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}
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/*
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* We first remap the interrupt controllers, and then we install
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* the appropriate ISRs to the correct entries in the IDT. This
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* is just like installing the exception handlers
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*/
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static void irq_install(void)
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{
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irq_remap();
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idt_set_gate(32, (unsigned)irq0, 0x08, 0x8E);
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idt_set_gate(33, (unsigned)irq1, 0x08, 0x8E);
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idt_set_gate(34, (unsigned)irq2, 0x08, 0x8E);
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idt_set_gate(35, (unsigned)irq3, 0x08, 0x8E);
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idt_set_gate(36, (unsigned)irq4, 0x08, 0x8E);
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idt_set_gate(37, (unsigned)irq5, 0x08, 0x8E);
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idt_set_gate(38, (unsigned)irq6, 0x08, 0x8E);
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idt_set_gate(39, (unsigned)irq7, 0x08, 0x8E);
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idt_set_gate(40, (unsigned)irq8, 0x08, 0x8E);
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idt_set_gate(41, (unsigned)irq9, 0x08, 0x8E);
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idt_set_gate(42, (unsigned)irq10, 0x08, 0x8E);
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idt_set_gate(43, (unsigned)irq11, 0x08, 0x8E);
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idt_set_gate(44, (unsigned)irq12, 0x08, 0x8E);
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idt_set_gate(45, (unsigned)irq13, 0x08, 0x8E);
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idt_set_gate(46, (unsigned)irq14, 0x08, 0x8E);
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idt_set_gate(47, (unsigned)irq15, 0x08, 0x8E);
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}
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void irq_init(void)
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{
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idt_install();
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isrs_install();
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irq_install();
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}
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/*
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* Each of the IRQ ISRs point to this function, rather than
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* the 'fault_handler' in 'isrs.c'. The IRQ Controllers need
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* to be told when you are done servicing them, so you need
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* to send them an "End of Interrupt" command (0x20). There
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* are two 8259 chips: The first exists at 0x20, the second
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* exists at 0xA0. If the second controller (an IRQ from 8 to
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* 15) gets an interrupt, you need to acknowledge the
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* interrupt at BOTH controllers, otherwise, you only send
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* an EOI command to the first controller. If you don't send
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* an EOI, you won't raise any more IRQs
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*/
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void irq_handler(struct regs *r)
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{
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/* This is a blank function pointer */
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void (*handler) (struct regs * r);
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/*
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* Find out if we have a custom handler to run for this
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* IRQ, and then finally, run it
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*/
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handler = irq_routines[r->int_no - 32];
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if (handler) {
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handler(r);
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}
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/*
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* If the IDT entry that was invoked was greater than 40
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* (meaning IRQ8 - 15), then we need to send an EOI to
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* the slave controller
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*/
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if (r->int_no >= 40) {
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outportb(0xA0, 0x20);
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}
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/*
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* In either case, we need to send an EOI to the master
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* interrupt controller too
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*/
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outportb(0x20, 0x20);
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}
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