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Annotation of Gnu-Mach/linux/src/arch/i386/kernel/irq.c, revision 1.1

1.1     ! root        1: /*
        !             2:  *     linux/arch/i386/kernel/irq.c
        !             3:  *
        !             4:  *     Copyright (C) 1992 Linus Torvalds
        !             5:  *
        !             6:  * This file contains the code used by various IRQ handling routines:
        !             7:  * asking for different IRQ's should be done through these routines
        !             8:  * instead of just grabbing them. Thus setups with different IRQ numbers
        !             9:  * shouldn't result in any weird surprises, and installing new handlers
        !            10:  * should be easier.
        !            11:  */
        !            12: 
        !            13: /*
        !            14:  * IRQ's are in fact implemented a bit like signal handlers for the kernel.
        !            15:  * Naturally it's not a 1:1 relation, but there are similarities.
        !            16:  */
        !            17: 
        !            18: #include <linux/ptrace.h>
        !            19: #include <linux/errno.h>
        !            20: #include <linux/kernel_stat.h>
        !            21: #include <linux/signal.h>
        !            22: #include <linux/sched.h>
        !            23: #include <linux/ioport.h>
        !            24: #include <linux/interrupt.h>
        !            25: #include <linux/timex.h>
        !            26: #include <linux/malloc.h>
        !            27: #include <linux/random.h>
        !            28: 
        !            29: #include <asm/system.h>
        !            30: #include <asm/io.h>
        !            31: #include <asm/irq.h>
        !            32: #include <asm/bitops.h>
        !            33: #include <asm/smp.h>
        !            34: 
        !            35: #define CR0_NE 32
        !            36: 
        !            37: static unsigned char cache_21 = 0xff;
        !            38: static unsigned char cache_A1 = 0xff;
        !            39: 
        !            40: #ifdef __SMP_PROF__
        !            41: static unsigned int int_count[NR_CPUS][NR_IRQS] = {{0},};
        !            42: #endif
        !            43: 
        !            44: static inline void mask_irq(unsigned int irq_nr)
        !            45: {
        !            46:        unsigned char mask;
        !            47: 
        !            48:        mask = 1 << (irq_nr & 7);
        !            49:        if (irq_nr < 8) {
        !            50:                cache_21 |= mask;
        !            51:                outb(cache_21,0x21);
        !            52:        } else {
        !            53:                cache_A1 |= mask;
        !            54:                outb(cache_A1,0xA1);
        !            55:        }
        !            56: }
        !            57: 
        !            58: static inline void unmask_irq(unsigned int irq_nr)
        !            59: {
        !            60:        unsigned char mask;
        !            61: 
        !            62:        mask = ~(1 << (irq_nr & 7));
        !            63:        if (irq_nr < 8) {
        !            64:                cache_21 &= mask;
        !            65:                outb(cache_21,0x21);
        !            66:        } else {
        !            67:                cache_A1 &= mask;
        !            68:                outb(cache_A1,0xA1);
        !            69:        }
        !            70: }
        !            71: 
        !            72: void disable_irq(unsigned int irq_nr)
        !            73: {
        !            74:        unsigned long flags;
        !            75: 
        !            76:        save_flags(flags);
        !            77:        cli();
        !            78:        mask_irq(irq_nr);
        !            79:        restore_flags(flags);
        !            80: }
        !            81: 
        !            82: void enable_irq(unsigned int irq_nr)
        !            83: {
        !            84:        unsigned long flags;
        !            85:        save_flags(flags);
        !            86:        cli();
        !            87:        unmask_irq(irq_nr);
        !            88:        restore_flags(flags);
        !            89: }
        !            90: 
        !            91: /*
        !            92:  * This builds up the IRQ handler stubs using some ugly macros in irq.h
        !            93:  *
        !            94:  * These macros create the low-level assembly IRQ routines that do all
        !            95:  * the operations that are needed to keep the AT interrupt-controller
        !            96:  * happy. They are also written to be fast - and to disable interrupts
        !            97:  * as little as humanly possible.
        !            98:  *
        !            99:  * NOTE! These macros expand to three different handlers for each line: one
        !           100:  * complete handler that does all the fancy stuff (including signal handling),
        !           101:  * and one fast handler that is meant for simple IRQ's that want to be
        !           102:  * atomic. The specific handler is chosen depending on the SA_INTERRUPT
        !           103:  * flag when installing a handler. Finally, one "bad interrupt" handler, that
        !           104:  * is used when no handler is present.
        !           105:  *
        !           106:  * The timer interrupt is handled specially to insure that the jiffies
        !           107:  * variable is updated at all times.  Specifically, the timer interrupt is
        !           108:  * just like the complete handlers except that it is invoked with interrupts
        !           109:  * disabled and should never re-enable them.  If other interrupts were
        !           110:  * allowed to be processed while the timer interrupt is active, then the
        !           111:  * other interrupts would have to avoid using the jiffies variable for delay
        !           112:  * and interval timing operations to avoid hanging the system.
        !           113:  */
        !           114: BUILD_TIMER_IRQ(FIRST,0,0x01)
        !           115: BUILD_IRQ(FIRST,1,0x02)
        !           116: BUILD_IRQ(FIRST,2,0x04)
        !           117: BUILD_IRQ(FIRST,3,0x08)
        !           118: BUILD_IRQ(FIRST,4,0x10)
        !           119: BUILD_IRQ(FIRST,5,0x20)
        !           120: BUILD_IRQ(FIRST,6,0x40)
        !           121: BUILD_IRQ(FIRST,7,0x80)
        !           122: BUILD_IRQ(SECOND,8,0x01)
        !           123: BUILD_IRQ(SECOND,9,0x02)
        !           124: BUILD_IRQ(SECOND,10,0x04)
        !           125: BUILD_IRQ(SECOND,11,0x08)
        !           126: BUILD_IRQ(SECOND,12,0x10)
        !           127: #ifdef __SMP__
        !           128: BUILD_MSGIRQ(SECOND,13,0x20)
        !           129: #else
        !           130: BUILD_IRQ(SECOND,13,0x20)
        !           131: #endif
        !           132: BUILD_IRQ(SECOND,14,0x40)
        !           133: BUILD_IRQ(SECOND,15,0x80)
        !           134: #ifdef __SMP__
        !           135: BUILD_RESCHEDIRQ(16)
        !           136: #endif
        !           137: 
        !           138: /*
        !           139:  * Pointers to the low-level handlers: first the general ones, then the
        !           140:  * fast ones, then the bad ones.
        !           141:  */
        !           142: static void (*interrupt[17])(void) = {
        !           143:        IRQ0_interrupt, IRQ1_interrupt, IRQ2_interrupt, IRQ3_interrupt,
        !           144:        IRQ4_interrupt, IRQ5_interrupt, IRQ6_interrupt, IRQ7_interrupt,
        !           145:        IRQ8_interrupt, IRQ9_interrupt, IRQ10_interrupt, IRQ11_interrupt,
        !           146:        IRQ12_interrupt, IRQ13_interrupt, IRQ14_interrupt, IRQ15_interrupt      
        !           147: #ifdef __SMP__ 
        !           148:        ,IRQ16_interrupt
        !           149: #endif
        !           150: };
        !           151: 
        !           152: static void (*fast_interrupt[16])(void) = {
        !           153:        fast_IRQ0_interrupt, fast_IRQ1_interrupt,
        !           154:        fast_IRQ2_interrupt, fast_IRQ3_interrupt,
        !           155:        fast_IRQ4_interrupt, fast_IRQ5_interrupt,
        !           156:        fast_IRQ6_interrupt, fast_IRQ7_interrupt,
        !           157:        fast_IRQ8_interrupt, fast_IRQ9_interrupt,
        !           158:        fast_IRQ10_interrupt, fast_IRQ11_interrupt,
        !           159:        fast_IRQ12_interrupt, fast_IRQ13_interrupt,
        !           160:        fast_IRQ14_interrupt, fast_IRQ15_interrupt
        !           161: };
        !           162: 
        !           163: static void (*bad_interrupt[16])(void) = {
        !           164:        bad_IRQ0_interrupt, bad_IRQ1_interrupt,
        !           165:        bad_IRQ2_interrupt, bad_IRQ3_interrupt,
        !           166:        bad_IRQ4_interrupt, bad_IRQ5_interrupt,
        !           167:        bad_IRQ6_interrupt, bad_IRQ7_interrupt,
        !           168:        bad_IRQ8_interrupt, bad_IRQ9_interrupt,
        !           169:        bad_IRQ10_interrupt, bad_IRQ11_interrupt,
        !           170:        bad_IRQ12_interrupt, bad_IRQ13_interrupt,
        !           171:        bad_IRQ14_interrupt, bad_IRQ15_interrupt
        !           172: };
        !           173: 
        !           174: /*
        !           175:  * Initial irq handlers.
        !           176:  */
        !           177: 
        !           178: static void no_action(int cpl, void *dev_id, struct pt_regs *regs) { }
        !           179: 
        !           180: #ifdef __SMP__
        !           181: 
        !           182: /*
        !           183:  * On SMP boards, irq13 is used for interprocessor interrupts (IPI's).
        !           184:  */
        !           185: static struct irqaction irq13 = { smp_message_irq, SA_INTERRUPT, 0, "IPI", NULL, NULL };
        !           186: 
        !           187: #else
        !           188: 
        !           189: /*
        !           190:  * Note that on a 486, we don't want to do a SIGFPE on a irq13
        !           191:  * as the irq is unreliable, and exception 16 works correctly
        !           192:  * (ie as explained in the intel literature). On a 386, you
        !           193:  * can't use exception 16 due to bad IBM design, so we have to
        !           194:  * rely on the less exact irq13.
        !           195:  *
        !           196:  * Careful.. Not only is IRQ13 unreliable, but it is also
        !           197:  * leads to races. IBM designers who came up with it should
        !           198:  * be shot.
        !           199:  */
        !           200:  
        !           201: 
        !           202: static void math_error_irq(int cpl, void *dev_id, struct pt_regs *regs)
        !           203: {
        !           204:        outb(0,0xF0);
        !           205:        if (ignore_irq13 || !hard_math)
        !           206:                return;
        !           207:        math_error();
        !           208: }
        !           209: 
        !           210: static struct irqaction irq13 = { math_error_irq, 0, 0, "math error", NULL, NULL };
        !           211: 
        !           212: #endif
        !           213: 
        !           214: /*
        !           215:  * IRQ2 is cascade interrupt to second interrupt controller
        !           216:  */
        !           217: static struct irqaction irq2  = { no_action, 0, 0, "cascade", NULL, NULL};
        !           218: 
        !           219: static struct irqaction *irq_action[16] = {
        !           220:        NULL, NULL, NULL, NULL,
        !           221:        NULL, NULL, NULL, NULL,
        !           222:        NULL, NULL, NULL, NULL,
        !           223:        NULL, NULL, NULL, NULL
        !           224: };
        !           225: 
        !           226: int get_irq_list(char *buf)
        !           227: {
        !           228:        int i, len = 0;
        !           229:        struct irqaction * action;
        !           230: 
        !           231:        for (i = 0 ; i < 16 ; i++) {
        !           232:                action = irq_action[i];
        !           233:                if (!action) 
        !           234:                        continue;
        !           235:                len += sprintf(buf+len, "%2d: %10u %c %s",
        !           236:                        i, kstat.interrupts[i],
        !           237:                        (action->flags & SA_INTERRUPT) ? '+' : ' ',
        !           238:                        action->name);
        !           239:                for (action=action->next; action; action = action->next) {
        !           240:                        len += sprintf(buf+len, ",%s %s",
        !           241:                                (action->flags & SA_INTERRUPT) ? " +" : "",
        !           242:                                action->name);
        !           243:                }
        !           244:                len += sprintf(buf+len, "\n");
        !           245:        }
        !           246: /*
        !           247:  *     Linus - should you add NMI counts here ?????
        !           248:  */
        !           249: #ifdef __SMP_PROF__
        !           250:        len+=sprintf(buf+len, "IPI: %8lu received\n",
        !           251:                ipi_count);
        !           252: #endif         
        !           253:        return len;
        !           254: }
        !           255: 
        !           256: #ifdef __SMP_PROF__
        !           257: 
        !           258: int get_smp_prof_list(char *buf) {
        !           259:        int i,j, len = 0;
        !           260:        struct irqaction * action;
        !           261:        unsigned long sum_spins = 0;
        !           262:        unsigned long sum_spins_syscall = 0;
        !           263:        unsigned long sum_spins_sys_idle = 0;
        !           264:        unsigned long sum_smp_idle_count = 0;
        !           265: 
        !           266:        for (i=0;i<smp_num_cpus;i++) {
        !           267:                int cpunum = cpu_logical_map[i];
        !           268:                sum_spins+=smp_spins[cpunum];
        !           269:                sum_spins_syscall+=smp_spins_syscall[cpunum];
        !           270:                sum_spins_sys_idle+=smp_spins_sys_idle[cpunum];
        !           271:                sum_smp_idle_count+=smp_idle_count[cpunum];
        !           272:        }
        !           273: 
        !           274:        len += sprintf(buf+len,"CPUS: %10i \n", smp_num_cpus);
        !           275:        len += sprintf(buf+len,"            SUM ");
        !           276:        for (i=0;i<smp_num_cpus;i++)
        !           277:                len += sprintf(buf+len,"        P%1d ",cpu_logical_map[i]);
        !           278:        len += sprintf(buf+len,"\n");
        !           279:        for (i = 0 ; i < NR_IRQS ; i++) {
        !           280:                action = *(i + irq_action);
        !           281:                if (!action || !action->handler)
        !           282:                        continue;
        !           283:                len += sprintf(buf+len, "%3d: %10d ",
        !           284:                        i, kstat.interrupts[i]);
        !           285:                for (j=0;j<smp_num_cpus;j++)
        !           286:                        len+=sprintf(buf+len, "%10d ",
        !           287:                                int_count[cpu_logical_map[j]][i]);
        !           288:                len += sprintf(buf+len, "%c %s",
        !           289:                        (action->flags & SA_INTERRUPT) ? '+' : ' ',
        !           290:                        action->name);
        !           291:                for (action=action->next; action; action = action->next) {
        !           292:                        len += sprintf(buf+len, ",%s %s",
        !           293:                                (action->flags & SA_INTERRUPT) ? " +" : "",
        !           294:                                action->name);
        !           295:                }
        !           296:                len += sprintf(buf+len, "\n");
        !           297:        }
        !           298:        len+=sprintf(buf+len, "LCK: %10lu",
        !           299:                sum_spins);
        !           300: 
        !           301:        for (i=0;i<smp_num_cpus;i++)
        !           302:                len+=sprintf(buf+len," %10lu",smp_spins[cpu_logical_map[i]]);
        !           303: 
        !           304:        len +=sprintf(buf+len,"   spins from int\n");
        !           305: 
        !           306:        len+=sprintf(buf+len, "LCK: %10lu",
        !           307:                sum_spins_syscall);
        !           308: 
        !           309:        for (i=0;i<smp_num_cpus;i++)
        !           310:                len+=sprintf(buf+len," %10lu",smp_spins_syscall[cpu_logical_map[i]]);
        !           311: 
        !           312:        len +=sprintf(buf+len,"   spins from syscall\n");
        !           313: 
        !           314:        len+=sprintf(buf+len, "LCK: %10lu",
        !           315:                sum_spins_sys_idle);
        !           316: 
        !           317:        for (i=0;i<smp_num_cpus;i++)
        !           318:                len+=sprintf(buf+len," %10lu",smp_spins_sys_idle[cpu_logical_map[i]]);
        !           319: 
        !           320:        len +=sprintf(buf+len,"   spins from sysidle\n");
        !           321:        len+=sprintf(buf+len,"IDLE %10lu",sum_smp_idle_count);
        !           322: 
        !           323:        for (i=0;i<smp_num_cpus;i++)
        !           324:                len+=sprintf(buf+len," %10lu",smp_idle_count[cpu_logical_map[i]]);
        !           325: 
        !           326:        len +=sprintf(buf+len,"   idle ticks\n");
        !           327: 
        !           328:        len+=sprintf(buf+len, "IPI: %10lu   received\n",
        !           329:                ipi_count);
        !           330: 
        !           331:        return len;
        !           332: }
        !           333: #endif 
        !           334: 
        !           335: 
        !           336: 
        !           337: /*
        !           338:  * do_IRQ handles IRQ's that have been installed without the
        !           339:  * SA_INTERRUPT flag: it uses the full signal-handling return
        !           340:  * and runs with other interrupts enabled. All relatively slow
        !           341:  * IRQ's should use this format: notably the keyboard/timer
        !           342:  * routines.
        !           343:  */
        !           344: asmlinkage void do_IRQ(int irq, struct pt_regs * regs)
        !           345: {
        !           346:        struct irqaction * action = *(irq + irq_action);
        !           347:        int do_random = 0;
        !           348:        int c,intm,mask;
        !           349: #ifdef IRQ_DEBUG
        !           350:        static int count;
        !           351:        if (smp_processor_id() != 0 && count++ < 1000)
        !           352:          printk("IRQ %d: done by CPU %d\n",irq,smp_processor_id());
        !           353: #endif   
        !           354:        if (irq  >= 8) {
        !           355:          c = cache_A1;
        !           356:          intm = inb(0xA1);
        !           357:          mask =  1 << (irq - 8);
        !           358:        } else {
        !           359:          c = cache_21;
        !           360:          intm = inb(0x21);
        !           361:          mask =  1 << irq;
        !           362:        }
        !           363:        if (!(c & mask) || !(intm & mask)) {
        !           364: #ifdef IRQ_DEBUG       
        !           365:          printk("IRQ %d (proc %d):cache_x1=0x%x,INT mask=0x%x\n", irq, smp_processor_id(),c,intm);
        !           366: #endif   
        !           367:          /* better to return because the interrupt may be asserted again,
        !           368:             the bad thing is that we may loose some interrupts */
        !           369:          return;
        !           370:        }
        !           371: #ifdef __SMP__
        !           372:        if(smp_threads_ready && active_kernel_processor!=smp_processor_id())
        !           373:                panic("IRQ %d: active processor set wrongly(%d not %d).\n", irq, active_kernel_processor, smp_processor_id());
        !           374: #endif
        !           375: 
        !           376:        kstat.interrupts[irq]++;
        !           377: #ifdef __SMP_PROF__
        !           378:        int_count[smp_processor_id()][irq]++;
        !           379: #endif
        !           380:        while (action) {
        !           381:                do_random |= action->flags;
        !           382:                action->handler(irq, action->dev_id, regs);
        !           383:                action = action->next;
        !           384:        }
        !           385:        if (do_random & SA_SAMPLE_RANDOM)
        !           386:                add_interrupt_randomness(irq);
        !           387: }
        !           388: 
        !           389: /*
        !           390:  * do_fast_IRQ handles IRQ's that don't need the fancy interrupt return
        !           391:  * stuff - the handler is also running with interrupts disabled unless
        !           392:  * it explicitly enables them later.
        !           393:  */
        !           394: asmlinkage void do_fast_IRQ(int irq)
        !           395: {
        !           396:        struct irqaction * action = *(irq + irq_action);
        !           397:        int do_random = 0;
        !           398:        
        !           399: #ifdef __SMP__
        !           400:        /* IRQ 13 is allowed - that's a flush tlb */
        !           401:        if(smp_threads_ready && active_kernel_processor!=smp_processor_id() && irq!=13)
        !           402:                panic("fast_IRQ %d: active processor set wrongly(%d not %d).\n", irq, active_kernel_processor, smp_processor_id());
        !           403: #endif
        !           404: 
        !           405:        kstat.interrupts[irq]++;
        !           406: #ifdef __SMP_PROF__
        !           407:        int_count[smp_processor_id()][irq]++;
        !           408: #endif
        !           409:        while (action) {
        !           410:                do_random |= action->flags;
        !           411:                action->handler(irq, action->dev_id, NULL);
        !           412:                action = action->next;
        !           413:        }
        !           414:        if (do_random & SA_SAMPLE_RANDOM)
        !           415:                add_interrupt_randomness(irq);
        !           416: }
        !           417: 
        !           418: int setup_x86_irq(int irq, struct irqaction * new)
        !           419: {
        !           420:        int shared = 0;
        !           421:        struct irqaction *old, **p;
        !           422:        unsigned long flags;
        !           423: 
        !           424:        p = irq_action + irq;
        !           425:        if ((old = *p) != NULL) {
        !           426:                /* Can't share interrupts unless both agree to */
        !           427:                if (!(old->flags & new->flags & SA_SHIRQ))
        !           428:                        return -EBUSY;
        !           429: 
        !           430:                /* Can't share interrupts unless both are same type */
        !           431:                if ((old->flags ^ new->flags) & SA_INTERRUPT)
        !           432:                        return -EBUSY;
        !           433: 
        !           434:                /* add new interrupt at end of irq queue */
        !           435:                do {
        !           436:                        p = &old->next;
        !           437:                        old = *p;
        !           438:                } while (old);
        !           439:                shared = 1;
        !           440:        }
        !           441: 
        !           442:        if (new->flags & SA_SAMPLE_RANDOM)
        !           443:                rand_initialize_irq(irq);
        !           444: 
        !           445:        save_flags(flags);
        !           446:        cli();
        !           447:        *p = new;
        !           448: 
        !           449:        if (!shared) {
        !           450:                if (new->flags & SA_INTERRUPT)
        !           451:                        set_intr_gate(0x20+irq,fast_interrupt[irq]);
        !           452:                else
        !           453:                        set_intr_gate(0x20+irq,interrupt[irq]);
        !           454:                unmask_irq(irq);
        !           455:        }
        !           456:        restore_flags(flags);
        !           457:        return 0;
        !           458: }
        !           459: 
        !           460: int request_irq(unsigned int irq, 
        !           461:                void (*handler)(int, void *, struct pt_regs *),
        !           462:                unsigned long irqflags, 
        !           463:                const char * devname,
        !           464:                void *dev_id)
        !           465: {
        !           466:        int retval;
        !           467:        struct irqaction * action;
        !           468: 
        !           469:        if (irq > 15)
        !           470:                return -EINVAL;
        !           471:        if (!handler)
        !           472:                return -EINVAL;
        !           473: 
        !           474:        action = (struct irqaction *)kmalloc(sizeof(struct irqaction), GFP_KERNEL);
        !           475:        if (!action)
        !           476:                return -ENOMEM;
        !           477: 
        !           478:        action->handler = handler;
        !           479:        action->flags = irqflags;
        !           480:        action->mask = 0;
        !           481:        action->name = devname;
        !           482:        action->next = NULL;
        !           483:        action->dev_id = dev_id;
        !           484: 
        !           485:        retval = setup_x86_irq(irq, action);
        !           486: 
        !           487:        if (retval)
        !           488:                kfree(action);
        !           489:        return retval;
        !           490: }
        !           491:                
        !           492: void free_irq(unsigned int irq, void *dev_id)
        !           493: {
        !           494:        struct irqaction * action, **p;
        !           495:        unsigned long flags;
        !           496: 
        !           497:        if (irq > 15) {
        !           498:                printk("Trying to free IRQ%d\n",irq);
        !           499:                return;
        !           500:        }
        !           501:        for (p = irq + irq_action; (action = *p) != NULL; p = &action->next) {
        !           502:                if (action->dev_id != dev_id)
        !           503:                        continue;
        !           504: 
        !           505:                /* Found it - now free it */
        !           506:                save_flags(flags);
        !           507:                cli();
        !           508:                *p = action->next;
        !           509:                if (!irq[irq_action]) {
        !           510:                        mask_irq(irq);
        !           511:                        set_intr_gate(0x20+irq,bad_interrupt[irq]);
        !           512:                }
        !           513:                restore_flags(flags);
        !           514:                kfree(action);
        !           515:                return;
        !           516:        }
        !           517:        printk("Trying to free free IRQ%d\n",irq);
        !           518: }
        !           519: 
        !           520: unsigned long probe_irq_on (void)
        !           521: {
        !           522:        unsigned int i, irqs = 0, irqmask;
        !           523:        unsigned long delay;
        !           524: 
        !           525:        /* first, enable any unassigned irqs */
        !           526:        for (i = 15; i > 0; i--) {
        !           527:                if (!irq_action[i]) {
        !           528:                        enable_irq(i);
        !           529:                        irqs |= (1 << i);
        !           530:                }
        !           531:        }
        !           532: 
        !           533:        /* wait for spurious interrupts to mask themselves out again */
        !           534:        for (delay = jiffies + HZ/10; delay > jiffies; )
        !           535:                /* about 100ms delay */;
        !           536: 
        !           537:        /* now filter out any obviously spurious interrupts */
        !           538:        irqmask = (((unsigned int)cache_A1)<<8) | (unsigned int)cache_21;
        !           539:        return irqs & ~irqmask;
        !           540: }
        !           541: 
        !           542: int probe_irq_off (unsigned long irqs)
        !           543: {
        !           544:        unsigned int i, irqmask;
        !           545: 
        !           546:        irqmask = (((unsigned int)cache_A1)<<8) | (unsigned int)cache_21;
        !           547: #ifdef DEBUG
        !           548:        printk("probe_irq_off: irqs=0x%04lx irqmask=0x%04x\n", irqs, irqmask);
        !           549: #endif
        !           550:        irqs &= irqmask;
        !           551:        if (!irqs)
        !           552:                return 0;
        !           553:        i = ffz(~irqs);
        !           554:        if (irqs != (irqs & (1 << i)))
        !           555:                i = -i;
        !           556:        return i;
        !           557: }
        !           558: 
        !           559: void init_IRQ(void)
        !           560: {
        !           561:        int i;
        !           562:        static unsigned char smptrap=0;
        !           563:        if(smptrap)
        !           564:                return;
        !           565:        smptrap=1;
        !           566: 
        !           567:        /* set the clock to 100 Hz */
        !           568:        outb_p(0x34,0x43);              /* binary, mode 2, LSB/MSB, ch 0 */
        !           569:        outb_p(LATCH & 0xff , 0x40);    /* LSB */
        !           570:        outb(LATCH >> 8 , 0x40);        /* MSB */
        !           571:        for (i = 0; i < 16 ; i++)
        !           572:                set_intr_gate(0x20+i,bad_interrupt[i]);
        !           573:        /* This bit is a hack because we don't send timer messages to all processors yet */
        !           574:        /* It has to be here .. it doesn't work if you put it down the bottom - assembler explodes 8) */
        !           575: #ifdef __SMP__ 
        !           576:        set_intr_gate(0x20+i, interrupt[i]);    /* IRQ '16' - IPI for rescheduling */
        !           577: #endif 
        !           578:        request_region(0x20,0x20,"pic1");
        !           579:        request_region(0xa0,0x20,"pic2");
        !           580:        setup_x86_irq(2, &irq2);
        !           581:        setup_x86_irq(13, &irq13);
        !           582: } 

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