341 lines
8.3 KiB
C
341 lines
8.3 KiB
C
/*
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* linux/kernel/irq.c
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*
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* Copyright (C) 1992 Linus Torvalds
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*
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* This file contains the code used by various IRQ handling routines:
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* asking for different IRQ's should be done through these routines
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* instead of just grabbing them. Thus setups with different IRQ numbers
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* shouldn't result in any weird surprises, and installing new handlers
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* should be easier.
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*/
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/*
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* IRQ's are in fact implemented a bit like signal handlers for the kernel.
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* The same sigaction struct is used, and with similar semantics (ie there
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* is a SA_INTERRUPT flag etc). Naturally it's not a 1:1 relation, but there
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* are similarities.
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*
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* sa_handler(int irq_NR) is the default function called.
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* sa_mask is 0 if nothing uses this IRQ
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* sa_flags contains various info: SA_INTERRUPT etc
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* sa_restorer is the unused
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*/
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#include <linux/ptrace.h>
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#include <linux/errno.h>
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#include <linux/kernel_stat.h>
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#include <linux/signal.h>
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#include <linux/sched.h>
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#include <linux/interrupt.h>
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#include <asm/system.h>
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#include <asm/io.h>
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#include <asm/irq.h>
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#define CR0_NE 32
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static unsigned char cache_21 = 0xff;
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static unsigned char cache_A1 = 0xff;
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unsigned long intr_count = 0;
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unsigned long bh_active = 0;
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unsigned long bh_mask = 0xFFFFFFFF;
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struct bh_struct bh_base[32];
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void disable_irq(unsigned int irq_nr)
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{
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unsigned long flags;
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unsigned char mask;
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mask = 1 << (irq_nr & 7);
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save_flags(flags);
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if (irq_nr < 8) {
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cli();
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cache_21 |= mask;
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outb(cache_21,0x21);
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restore_flags(flags);
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return;
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}
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cli();
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cache_A1 |= mask;
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outb(cache_A1,0xA1);
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restore_flags(flags);
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}
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void enable_irq(unsigned int irq_nr)
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{
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unsigned long flags;
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unsigned char mask;
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mask = ~(1 << (irq_nr & 7));
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save_flags(flags);
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if (irq_nr < 8) {
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cli();
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cache_21 &= mask;
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outb(cache_21,0x21);
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restore_flags(flags);
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return;
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}
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cli();
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cache_A1 &= mask;
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outb(cache_A1,0xA1);
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restore_flags(flags);
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}
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/*
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* do_bottom_half() runs at normal kernel priority: all interrupts
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* enabled. do_bottom_half() is atomic with respect to itself: a
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* bottom_half handler need not be re-entrant.
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*/
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asmlinkage void do_bottom_half(void)
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{
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unsigned long active;
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unsigned long mask, left;
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struct bh_struct *bh;
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bh = bh_base;
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active = bh_active & bh_mask;
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for (mask = 1, left = ~0 ; left & active ; bh++,mask += mask,left += left) {
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if (mask & active) {
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void (*fn)(void *);
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bh_active &= ~mask;
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fn = bh->routine;
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if (!fn)
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goto bad_bh;
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fn(bh->data);
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}
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}
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return;
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bad_bh:
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printk ("irq.c:bad bottom half entry\n");
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}
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/*
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* This builds up the IRQ handler stubs using some ugly macros in irq.h
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*
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* These macros create the low-level assembly IRQ routines that do all
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* the operations that are needed to keep the AT interrupt-controller
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* happy. They are also written to be fast - and to disable interrupts
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* as little as humanly possible.
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*
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* NOTE! These macros expand to three different handlers for each line: one
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* complete handler that does all the fancy stuff (including signal handling),
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* and one fast handler that is meant for simple IRQ's that want to be
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* atomic. The specific handler is chosen depending on the SA_INTERRUPT
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* flag when installing a handler. Finally, one "bad interrupt" handler, that
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* is used when no handler is present.
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*/
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BUILD_IRQ(FIRST,0,0x01)
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BUILD_IRQ(FIRST,1,0x02)
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BUILD_IRQ(FIRST,2,0x04)
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BUILD_IRQ(FIRST,3,0x08)
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BUILD_IRQ(FIRST,4,0x10)
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BUILD_IRQ(FIRST,5,0x20)
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BUILD_IRQ(FIRST,6,0x40)
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BUILD_IRQ(FIRST,7,0x80)
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BUILD_IRQ(SECOND,8,0x01)
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BUILD_IRQ(SECOND,9,0x02)
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BUILD_IRQ(SECOND,10,0x04)
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BUILD_IRQ(SECOND,11,0x08)
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BUILD_IRQ(SECOND,12,0x10)
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BUILD_IRQ(SECOND,13,0x20)
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BUILD_IRQ(SECOND,14,0x40)
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BUILD_IRQ(SECOND,15,0x80)
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/*
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* Pointers to the low-level handlers: first the general ones, then the
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* fast ones, then the bad ones.
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*/
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static void (*interrupt[16])(void) = {
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IRQ0_interrupt, IRQ1_interrupt, IRQ2_interrupt, IRQ3_interrupt,
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IRQ4_interrupt, IRQ5_interrupt, IRQ6_interrupt, IRQ7_interrupt,
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IRQ8_interrupt, IRQ9_interrupt, IRQ10_interrupt, IRQ11_interrupt,
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IRQ12_interrupt, IRQ13_interrupt, IRQ14_interrupt, IRQ15_interrupt
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};
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static void (*fast_interrupt[16])(void) = {
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fast_IRQ0_interrupt, fast_IRQ1_interrupt,
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fast_IRQ2_interrupt, fast_IRQ3_interrupt,
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fast_IRQ4_interrupt, fast_IRQ5_interrupt,
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fast_IRQ6_interrupt, fast_IRQ7_interrupt,
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fast_IRQ8_interrupt, fast_IRQ9_interrupt,
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fast_IRQ10_interrupt, fast_IRQ11_interrupt,
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fast_IRQ12_interrupt, fast_IRQ13_interrupt,
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fast_IRQ14_interrupt, fast_IRQ15_interrupt
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};
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static void (*bad_interrupt[16])(void) = {
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bad_IRQ0_interrupt, bad_IRQ1_interrupt,
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bad_IRQ2_interrupt, bad_IRQ3_interrupt,
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bad_IRQ4_interrupt, bad_IRQ5_interrupt,
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bad_IRQ6_interrupt, bad_IRQ7_interrupt,
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bad_IRQ8_interrupt, bad_IRQ9_interrupt,
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bad_IRQ10_interrupt, bad_IRQ11_interrupt,
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bad_IRQ12_interrupt, bad_IRQ13_interrupt,
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bad_IRQ14_interrupt, bad_IRQ15_interrupt
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};
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/*
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* Initial irq handlers.
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*/
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static struct sigaction irq_sigaction[16] = {
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{ NULL, 0, 0, NULL }, { NULL, 0, 0, NULL },
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{ NULL, 0, 0, NULL }, { NULL, 0, 0, NULL },
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{ NULL, 0, 0, NULL }, { NULL, 0, 0, NULL },
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{ NULL, 0, 0, NULL }, { NULL, 0, 0, NULL },
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{ NULL, 0, 0, NULL }, { NULL, 0, 0, NULL },
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{ NULL, 0, 0, NULL }, { NULL, 0, 0, NULL },
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{ NULL, 0, 0, NULL }, { NULL, 0, 0, NULL },
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{ NULL, 0, 0, NULL }, { NULL, 0, 0, NULL }
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};
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/*
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* do_IRQ handles IRQ's that have been installed without the
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* SA_INTERRUPT flag: it uses the full signal-handling return
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* and runs with other interrupts enabled. All relatively slow
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* IRQ's should use this format: notably the keyboard/timer
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* routines.
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*/
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asmlinkage void do_IRQ(int irq, struct pt_regs * regs)
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{
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struct sigaction * sa = irq + irq_sigaction;
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kstat.interrupts++;
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sa->sa_handler((int) regs);
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}
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/*
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* do_fast_IRQ handles IRQ's that don't need the fancy interrupt return
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* stuff - the handler is also running with interrupts disabled unless
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* it explicitly enables them later.
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*/
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asmlinkage void do_fast_IRQ(int irq)
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{
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struct sigaction * sa = irq + irq_sigaction;
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kstat.interrupts++;
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sa->sa_handler(irq);
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}
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int irqaction(unsigned int irq, struct sigaction * new_sa)
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{
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struct sigaction * sa;
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unsigned long flags;
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if (irq > 15)
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return -EINVAL;
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sa = irq + irq_sigaction;
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if (sa->sa_mask)
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return -EBUSY;
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if (!new_sa->sa_handler)
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return -EINVAL;
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save_flags(flags);
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cli();
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*sa = *new_sa;
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sa->sa_mask = 1;
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if (sa->sa_flags & SA_INTERRUPT)
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set_intr_gate(0x20+irq,fast_interrupt[irq]);
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else
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set_intr_gate(0x20+irq,interrupt[irq]);
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if (irq < 8) {
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cache_21 &= ~(1<<irq);
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outb(cache_21,0x21);
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} else {
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cache_21 &= ~(1<<2);
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cache_A1 &= ~(1<<(irq-8));
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outb(cache_21,0x21);
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outb(cache_A1,0xA1);
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}
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restore_flags(flags);
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return 0;
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}
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int request_irq(unsigned int irq, void (*handler)(int))
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{
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struct sigaction sa;
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sa.sa_handler = handler;
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sa.sa_flags = 0;
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sa.sa_mask = 0;
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sa.sa_restorer = NULL;
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return irqaction(irq,&sa);
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}
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void free_irq(unsigned int irq)
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{
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struct sigaction * sa = irq + irq_sigaction;
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unsigned long flags;
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if (irq > 15) {
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printk("Trying to free IRQ%d\n",irq);
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return;
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}
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if (!sa->sa_mask) {
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printk("Trying to free free IRQ%d\n",irq);
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return;
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}
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save_flags(flags);
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cli();
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if (irq < 8) {
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cache_21 |= 1 << irq;
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outb(cache_21,0x21);
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} else {
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cache_A1 |= 1 << (irq-8);
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outb(cache_A1,0xA1);
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}
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set_intr_gate(0x20+irq,bad_interrupt[irq]);
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sa->sa_handler = NULL;
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sa->sa_flags = 0;
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sa->sa_mask = 0;
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sa->sa_restorer = NULL;
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restore_flags(flags);
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}
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/*
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* Note that on a 486, we don't want to do a SIGFPE on a irq13
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* as the irq is unreliable, and exception 16 works correctly
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* (ie as explained in the intel litterature). On a 386, you
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* can't use exception 16 due to bad IBM design, so we have to
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* rely on the less exact irq13.
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*
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* Careful.. Not only is IRQ13 unreliable, but it is also
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* leads to races. IBM designers who came up with it should
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* be shot.
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*/
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static void math_error_irq(int cpl)
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{
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outb(0,0xF0);
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if (ignore_irq13)
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return;
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math_error();
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}
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static void no_action(int cpl) { }
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static struct sigaction ignore_IRQ = {
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no_action,
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0,
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SA_INTERRUPT,
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NULL
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};
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void init_IRQ(void)
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{
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int i;
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for (i = 0; i < 16 ; i++)
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set_intr_gate(0x20+i,bad_interrupt[i]);
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if (irqaction(2,&ignore_IRQ))
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printk("Unable to get IRQ2 for cascade\n");
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if (request_irq(13,math_error_irq))
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printk("Unable to get IRQ13 for math-error handler\n");
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/* intialize the bottom half routines. */
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for (i = 0; i < 32; i++) {
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bh_base[i].routine = NULL;
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bh_base[i].data = NULL;
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}
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bh_active = 0;
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intr_count = 0;
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}
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