179 lines
4.8 KiB
C
179 lines
4.8 KiB
C
/*
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* The Minix hardware interrupt system.
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*
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* This file contains routines for managing the interrupt
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* controller.
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*
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* put_irq_handler: register an interrupt handler.
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* rm_irq_handler: deregister an interrupt handler.
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* irq_handle: handle a hardware interrupt.
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* called by the system dependent part when an
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* external interrupt occurs.
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* enable_irq: enable hook for IRQ.
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* disable_irq: disable hook for IRQ.
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*/
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#include <assert.h>
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#include "kernel/kernel.h"
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#include "archconst.h"
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#include "hw_intr.h"
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/* number of lists of IRQ hooks, one list per supported line. */
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static irq_hook_t* irq_handlers[NR_IRQ_VECTORS] = {0};
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/*===========================================================================*
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* put_irq_handler *
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*===========================================================================*/
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/* Register an interrupt handler. */
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void put_irq_handler( irq_hook_t* hook, int irq,
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const irq_handler_t handler)
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{
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int id;
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irq_hook_t **line;
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unsigned long bitmap;
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if( irq < 0 || irq >= NR_IRQ_VECTORS )
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panic("invalid call to put_irq_handler: %d", irq);
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line = &irq_handlers[irq];
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bitmap = 0;
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while ( *line != NULL ) {
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if(hook == *line) return; /* extra initialization */
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bitmap |= (*line)->id; /* mark ids in use */
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line = &(*line)->next;
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}
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/* find the lowest id not in use */
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for (id = 1; id != 0; id <<= 1)
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if (!(bitmap & id)) break;
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if(id == 0)
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panic("Too many handlers for irq: %d", irq);
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hook->next = NULL;
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hook->handler = handler;
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hook->irq = irq;
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hook->id = id;
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*line = hook;
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/* And as last enable the irq at the hardware.
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*
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* Internal this activates the line or source of the given interrupt.
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*/
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if((irq_actids[hook->irq] &= ~hook->id) == 0) {
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hw_intr_used(irq);
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hw_intr_unmask(hook->irq);
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}
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}
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/*===========================================================================*
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* rm_irq_handler *
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*===========================================================================*/
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/* Unregister an interrupt handler. */
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void rm_irq_handler( const irq_hook_t* hook ) {
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const int irq = hook->irq;
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const int id = hook->id;
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irq_hook_t **line;
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if( irq < 0 || irq >= NR_IRQ_VECTORS )
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panic("invalid call to rm_irq_handler: %d", irq);
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/* remove the hook */
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line = &irq_handlers[irq];
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while( (*line) != NULL ) {
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if((*line)->id == id) {
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(*line) = (*line)->next;
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if (irq_actids[irq] & id)
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irq_actids[irq] &= ~id;
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}
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else {
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line = &(*line)->next;
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}
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}
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/* Disable the irq if there are no other handlers registered.
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* If the irq is shared, reenable it if there is no active handler.
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*/
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if (irq_handlers[irq] == NULL) {
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hw_intr_mask(irq);
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hw_intr_not_used(irq);
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}
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else if (irq_actids[irq] == 0) {
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hw_intr_unmask(irq);
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}
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}
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/*===========================================================================*
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* irq_handle *
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*===========================================================================*/
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/*
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* The function first disables interrupt is need be and restores the state at
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* the end. Before returning, it unmasks the IRQ if and only if all active ID
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* bits are cleared, and restart a process.
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*/
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void irq_handle(int irq)
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{
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irq_hook_t * hook;
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/* here we need not to get this IRQ until all the handlers had a say */
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assert(irq >= 0 && irq < NR_IRQ_VECTORS);
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hw_intr_mask(irq);
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hook = irq_handlers[irq];
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/* Check for spurious interrupts. */
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if(hook == NULL) {
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static int nspurious[NR_IRQ_VECTORS], report_interval = 100;
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nspurious[irq]++;
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if(nspurious[irq] == 1 || !(nspurious[irq] % report_interval)) {
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printf("irq_handle: spurious irq %d (count: %d); keeping masked\n",
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irq, nspurious[irq]);
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if(report_interval < INT_MAX/2)
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report_interval *= 2;
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}
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return;
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}
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/* Call list of handlers for an IRQ. */
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while( hook != NULL ) {
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/* For each handler in the list, mark it active by setting its ID bit,
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* call the function, and unmark it if the function returns true.
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*/
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irq_actids[irq] |= hook->id;
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/* Call the hooked function. */
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if( (*hook->handler)(hook) )
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irq_actids[hook->irq] &= ~hook->id;
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/* Next hooked function. */
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hook = hook->next;
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}
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/* reenable the IRQ only if there is no active handler */
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if (irq_actids[irq] == 0)
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hw_intr_unmask(irq);
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hw_intr_ack(irq);
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}
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/* Enable/Disable a interrupt line. */
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void enable_irq(const irq_hook_t *hook)
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{
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if((irq_actids[hook->irq] &= ~hook->id) == 0) {
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hw_intr_unmask(hook->irq);
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}
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}
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/* Return true if the interrupt was enabled before call. */
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int disable_irq(const irq_hook_t *hook)
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{
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if(irq_actids[hook->irq] & hook->id) /* already disabled */
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return 0;
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irq_actids[hook->irq] |= hook->id;
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hw_intr_mask(hook->irq);
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return TRUE;
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}
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