path: root/linux/src/arch/i386/kernel/irq.c

/*
 *	linux/arch/i386/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.
 * Naturally it's not a 1:1 relation, but there are similarities.
 */

#include <linux/ptrace.h>
#include <linux/errno.h>
#include <linux/kernel_stat.h>
#include <linux/signal.h>
#include <linux/sched.h>
#include <linux/ioport.h>
#include <linux/interrupt.h>
#include <linux/timex.h>
#include <linux/malloc.h>
#include <linux/random.h>

#include <asm/system.h>
#include <asm/io.h>
#include <asm/irq.h>
#include <asm/bitops.h>
#include <asm/smp.h>

#define CR0_NE 32

static unsigned char cache_21 = 0xff;
static unsigned char cache_A1 = 0xff;

#ifdef __SMP_PROF__
static unsigned int int_count[NR_CPUS][NR_IRQS] = {{0},};
#endif

static inline void mask_irq(unsigned int irq_nr)
{
	unsigned char mask;

	mask = 1 << (irq_nr & 7);
	if (irq_nr < 8) {
		cache_21 |= mask;
		outb(cache_21,0x21);
	} else {
		cache_A1 |= mask;
		outb(cache_A1,0xA1);
	}
}

static inline void unmask_irq(unsigned int irq_nr)
{
	unsigned char mask;

	mask = ~(1 << (irq_nr & 7));
	if (irq_nr < 8) {
		cache_21 &= mask;
		outb(cache_21,0x21);
	} else {
		cache_A1 &= mask;
		outb(cache_A1,0xA1);
	}
}

void disable_irq(unsigned int irq_nr)
{
	unsigned long flags;

	save_flags(flags);
	cli();
	mask_irq(irq_nr);
	restore_flags(flags);
}

void enable_irq(unsigned int irq_nr)
{
	unsigned long flags;
	save_flags(flags);
	cli();
	unmask_irq(irq_nr);
	restore_flags(flags);
}

/*
 * 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.
 *
 * The timer interrupt is handled specially to insure that the jiffies
 * variable is updated at all times.  Specifically, the timer interrupt is
 * just like the complete handlers except that it is invoked with interrupts
 * disabled and should never re-enable them.  If other interrupts were
 * allowed to be processed while the timer interrupt is active, then the
 * other interrupts would have to avoid using the jiffies variable for delay
 * and interval timing operations to avoid hanging the system.
 */
BUILD_TIMER_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)
#ifdef __SMP__
BUILD_MSGIRQ(SECOND,13,0x20)
#else
BUILD_IRQ(SECOND,13,0x20)
#endif
BUILD_IRQ(SECOND,14,0x40)
BUILD_IRQ(SECOND,15,0x80)
#ifdef __SMP__
BUILD_RESCHEDIRQ(16)
#endif

/*
 * Pointers to the low-level handlers: first the general ones, then the
 * fast ones, then the bad ones.
 */
static void (*interrupt[17])(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	
#ifdef __SMP__	
	,IRQ16_interrupt
#endif
};

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 void no_action(int cpl, void *dev_id, struct pt_regs *regs) { }

#ifdef __SMP__

/*
 * On SMP boards, irq13 is used for interprocessor interrupts (IPI's).
 */
static struct irqaction irq13 = { smp_message_irq, SA_INTERRUPT, 0, "IPI", NULL, NULL };

#else

/*
 * 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 literature). 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, void *dev_id, struct pt_regs *regs)
{
	outb(0,0xF0);
	if (ignore_irq13 || !hard_math)
		return;
	math_error();
}

static struct irqaction irq13 = { math_error_irq, 0, 0, "math error", NULL, NULL };

#endif

/*
 * IRQ2 is cascade interrupt to second interrupt controller
 */
static struct irqaction irq2  = { no_action, 0, 0, "cascade", NULL, NULL};

static struct irqaction *irq_action[16] = {
	NULL, NULL, NULL, NULL,
	NULL, NULL, NULL, NULL,
	NULL, NULL, NULL, NULL,
	NULL, NULL, NULL, NULL
};

int get_irq_list(char *buf)
{
	int i, len = 0;
	struct irqaction * action;

	for (i = 0 ; i < 16 ; i++) {
		action = irq_action[i];
		if (!action) 
			continue;
		len += sprintf(buf+len, "%2d: %10u %c %s",
			i, kstat.interrupts[i],
			(action->flags & SA_INTERRUPT) ? '+' : ' ',
			action->name);
		for (action=action->next; action; action = action->next) {
			len += sprintf(buf+len, ",%s %s",
				(action->flags & SA_INTERRUPT) ? " +" : "",
				action->name);
		}
		len += sprintf(buf+len, "\n");
	}
/*
 *	Linus - should you add NMI counts here ?????
 */
#ifdef __SMP_PROF__
	len+=sprintf(buf+len, "IPI: %8lu received\n",
		ipi_count);
#endif		
	return len;
}

#ifdef __SMP_PROF__

int get_smp_prof_list(char *buf) {
	int i,j, len = 0;
	struct irqaction * action;
	unsigned long sum_spins = 0;
	unsigned long sum_spins_syscall = 0;
	unsigned long sum_spins_sys_idle = 0;
	unsigned long sum_smp_idle_count = 0;

	for (i=0;i<smp_num_cpus;i++) {
		int cpunum = cpu_logical_map[i];
		sum_spins+=smp_spins[cpunum];
		sum_spins_syscall+=smp_spins_syscall[cpunum];
		sum_spins_sys_idle+=smp_spins_sys_idle[cpunum];
		sum_smp_idle_count+=smp_idle_count[cpunum];
	}

	len += sprintf(buf+len,"CPUS: %10i \n", smp_num_cpus);
	len += sprintf(buf+len,"            SUM ");
	for (i=0;i<smp_num_cpus;i++)
		len += sprintf(buf+len,"        P%1d ",cpu_logical_map[i]);
	len += sprintf(buf+len,"\n");
	for (i = 0 ; i < NR_IRQS ; i++) {
		action = *(i + irq_action);
		if (!action || !action->handler)
			continue;
		len += sprintf(buf+len, "%3d: %10d ",
			i, kstat.interrupts[i]);
		for (j=0;j<smp_num_cpus;j++)
			len+=sprintf(buf+len, "%10d ",
				int_count[cpu_logical_map[j]][i]);
		len += sprintf(buf+len, "%c %s",
			(action->flags & SA_INTERRUPT) ? '+' : ' ',
			action->name);
		for (action=action->next; action; action = action->next) {
			len += sprintf(buf+len, ",%s %s",
				(action->flags & SA_INTERRUPT) ? " +" : "",
				action->name);
		}
		len += sprintf(buf+len, "\n");
	}
	len+=sprintf(buf+len, "LCK: %10lu",
		sum_spins);

	for (i=0;i<smp_num_cpus;i++)
		len+=sprintf(buf+len," %10lu",smp_spins[cpu_logical_map[i]]);

	len +=sprintf(buf+len,"   spins from int\n");

	len+=sprintf(buf+len, "LCK: %10lu",
		sum_spins_syscall);

	for (i=0;i<smp_num_cpus;i++)
		len+=sprintf(buf+len," %10lu",smp_spins_syscall[cpu_logical_map[i]]);

	len +=sprintf(buf+len,"   spins from syscall\n");

	len+=sprintf(buf+len, "LCK: %10lu",
		sum_spins_sys_idle);

	for (i=0;i<smp_num_cpus;i++)
		len+=sprintf(buf+len," %10lu",smp_spins_sys_idle[cpu_logical_map[i]]);

	len +=sprintf(buf+len,"   spins from sysidle\n");
	len+=sprintf(buf+len,"IDLE %10lu",sum_smp_idle_count);

	for (i=0;i<smp_num_cpus;i++)
		len+=sprintf(buf+len," %10lu",smp_idle_count[cpu_logical_map[i]]);

	len +=sprintf(buf+len,"   idle ticks\n");

	len+=sprintf(buf+len, "IPI: %10lu   received\n",
		ipi_count);

	return len;
}
#endif 



/*
 * 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 irqaction * action = *(irq + irq_action);
	int do_random = 0;
	int c,intm,mask;
#ifdef IRQ_DEBUG
	static int count;
	if (smp_processor_id() != 0 && count++ < 1000)
	  printk("IRQ %d: done by CPU %d\n",irq,smp_processor_id());
#endif	  
	if (irq  >= 8) {
	  c = cache_A1;
	  intm = inb(0xA1);
	  mask =  1 << (irq - 8);
	} else {
	  c = cache_21;
	  intm = inb(0x21);
	  mask =  1 << irq;
	}
	if (!(c & mask) || !(intm & mask)) {
#ifdef IRQ_DEBUG	
	  printk("IRQ %d (proc %d):cache_x1=0x%x,INT mask=0x%x\n", irq, smp_processor_id(),c,intm);
#endif	  
	  /* better to return because the interrupt may be asserted again,
	     the bad thing is that we may loose some interrupts */
	  return;
	}
#ifdef __SMP__
	if(smp_threads_ready && active_kernel_processor!=smp_processor_id())
		panic("IRQ %d: active processor set wrongly(%d not %d).\n", irq, active_kernel_processor, smp_processor_id());
#endif

	kstat.interrupts[irq]++;
#ifdef __SMP_PROF__
	int_count[smp_processor_id()][irq]++;
#endif
	while (action) {
		do_random |= action->flags;
		action->handler(irq, action->dev_id, regs);
		action = action->next;
	}
	if (do_random & SA_SAMPLE_RANDOM)
		add_interrupt_randomness(irq);
}

/*
 * 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 irqaction * action = *(irq + irq_action);
	int do_random = 0;
	
#ifdef __SMP__
	/* IRQ 13 is allowed - that's a flush tlb */
	if(smp_threads_ready && active_kernel_processor!=smp_processor_id() && irq!=13)
		panic("fast_IRQ %d: active processor set wrongly(%d not %d).\n", irq, active_kernel_processor, smp_processor_id());
#endif

	kstat.interrupts[irq]++;
#ifdef __SMP_PROF__
	int_count[smp_processor_id()][irq]++;
#endif
	while (action) {
		do_random |= action->flags;
		action->handler(irq, action->dev_id, NULL);
		action = action->next;
	}
	if (do_random & SA_SAMPLE_RANDOM)
		add_interrupt_randomness(irq);
}

int setup_x86_irq(int irq, struct irqaction * new)
{
	int shared = 0;
	struct irqaction *old, **p;
	unsigned long flags;

	p = irq_action + irq;
	if ((old = *p) != NULL) {
		/* Can't share interrupts unless both agree to */
		if (!(old->flags & new->flags & SA_SHIRQ))
			return -EBUSY;

		/* Can't share interrupts unless both are same type */
		if ((old->flags ^ new->flags) & SA_INTERRUPT)
			return -EBUSY;

		/* add new interrupt at end of irq queue */
		do {
			p = &old->next;
			old = *p;
		} while (old);
		shared = 1;
	}

	if (new->flags & SA_SAMPLE_RANDOM)
		rand_initialize_irq(irq);

	save_flags(flags);
	cli();
	*p = new;

	if (!shared) {
		if (new->flags & SA_INTERRUPT)
			set_intr_gate(0x20+irq,fast_interrupt[irq]);
		else
			set_intr_gate(0x20+irq,interrupt[irq]);
		unmask_irq(irq);
	}
	restore_flags(flags);
	return 0;
}

int request_irq(unsigned int irq, 
		void (*handler)(int, void *, struct pt_regs *),
		unsigned long irqflags, 
		const char * devname,
		void *dev_id)
{
	int retval;
	struct irqaction * action;

	if (irq > 15)
		return -EINVAL;
	if (!handler)
		return -EINVAL;

	action = (struct irqaction *)kmalloc(sizeof(struct irqaction), GFP_KERNEL);
	if (!action)
		return -ENOMEM;

	action->handler = handler;
	action->flags = irqflags;
	action->mask = 0;
	action->name = devname;
	action->next = NULL;
	action->dev_id = dev_id;

	retval = setup_x86_irq(irq, action);

	if (retval)
		kfree(action);
	return retval;
}
		
void free_irq(unsigned int irq, void *dev_id)
{
	struct irqaction * action, **p;
	unsigned long flags;

	if (irq > 15) {
		printk("Trying to free IRQ%d\n",irq);
		return;
	}
	for (p = irq + irq_action; (action = *p) != NULL; p = &action->next) {
		if (action->dev_id != dev_id)
			continue;

		/* Found it - now free it */
		save_flags(flags);
		cli();
		*p = action->next;
		if (!irq[irq_action]) {
			mask_irq(irq);
			set_intr_gate(0x20+irq,bad_interrupt[irq]);
		}
		restore_flags(flags);
		kfree(action);
		return;
	}
	printk("Trying to free free IRQ%d\n",irq);
}

unsigned long probe_irq_on (void)
{
	unsigned int i, irqs = 0, irqmask;
	unsigned long delay;

	/* first, enable any unassigned irqs */
	for (i = 15; i > 0; i--) {
		if (!irq_action[i]) {
			enable_irq(i);
			irqs |= (1 << i);
		}
	}

	/* wait for spurious interrupts to mask themselves out again */
	for (delay = jiffies + HZ/10; delay > jiffies; )
		/* about 100ms delay */;

	/* now filter out any obviously spurious interrupts */
	irqmask = (((unsigned int)cache_A1)<<8) | (unsigned int)cache_21;
	return irqs & ~irqmask;
}

int probe_irq_off (unsigned long irqs)
{
	unsigned int i, irqmask;

	irqmask = (((unsigned int)cache_A1)<<8) | (unsigned int)cache_21;
#ifdef DEBUG
	printk("probe_irq_off: irqs=0x%04lx irqmask=0x%04x\n", irqs, irqmask);
#endif
	irqs &= irqmask;
	if (!irqs)
		return 0;
	i = ffz(~irqs);
	if (irqs != (irqs & (1 << i)))
		i = -i;
	return i;
}

void init_IRQ(void)
{
	int i;
	static unsigned char smptrap=0;
	if(smptrap)
		return;
	smptrap=1;

	/* set the clock to 100 Hz */
	outb_p(0x34,0x43);		/* binary, mode 2, LSB/MSB, ch 0 */
	outb_p(LATCH & 0xff , 0x40);	/* LSB */
	outb(LATCH >> 8 , 0x40);	/* MSB */
	for (i = 0; i < 16 ; i++)
		set_intr_gate(0x20+i,bad_interrupt[i]);
	/* This bit is a hack because we don't send timer messages to all processors yet */
	/* It has to be here .. it doesn't work if you put it down the bottom - assembler explodes 8) */
#ifdef __SMP__	
	set_intr_gate(0x20+i, interrupt[i]);	/* IRQ '16' - IPI for rescheduling */
#endif	
	request_region(0x20,0x20,"pic1");
	request_region(0xa0,0x20,"pic2");
	setup_x86_irq(2, &irq2);
	setup_x86_irq(13, &irq13);
}