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