irq.c

来自「Linux Kernel 2.6.9 for OMAP1710」· C语言 代码 · 共 1,197 行 · 第 1/2 页

/*
 *	linux/arch/ia64/kernel/irq.c
 *
 *	Copyright (C) 1992, 1998 Linus Torvalds, Ingo Molnar
 *
 * 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.
 *
 * Copyright (C) Ashok Raj<[e-mail]>, Intel Corporation 2004
 *
 * 4/14/2004: Added code to handle cpu migration and do safe irq
 *			migration without lossing interrupts for iosapic
 *			architecture.
 */

/*
 * (mostly architecture independent, will move to kernel/irq.c in 2.5.)
 *
 * IRQs 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/config.h>
#include <linux/errno.h>
#include <linux/module.h>
#include <linux/signal.h>
#include <linux/sched.h>
#include <linux/ioport.h>
#include <linux/interrupt.h>
#include <linux/timex.h>
#include <linux/slab.h>
#include <linux/random.h>
#include <linux/cpu.h>
#include <linux/ctype.h>
#include <linux/smp_lock.h>
#include <linux/init.h>
#include <linux/kernel_stat.h>
#include <linux/irq.h>
#include <linux/proc_fs.h>
#include <linux/seq_file.h>
#include <linux/kallsyms.h>
#include <linux/notifier.h>

#include <asm/atomic.h>
#include <asm/cpu.h>
#include <asm/io.h>
#include <asm/smp.h>
#include <asm/system.h>
#include <asm/bitops.h>
#include <asm/uaccess.h>
#include <asm/pgalloc.h>
#include <asm/tlbflush.h>
#include <asm/delay.h>
#include <asm/irq.h>


/*
 * Linux has a controller-independent x86 interrupt architecture.
 * every controller has a 'controller-template', that is used
 * by the main code to do the right thing. Each driver-visible
 * interrupt source is transparently wired to the appropriate
 * controller. Thus drivers need not be aware of the
 * interrupt-controller.
 *
 * Various interrupt controllers we handle: 8259 PIC, SMP IO-APIC,
 * PIIX4's internal 8259 PIC and SGI's Visual Workstation Cobalt (IO-)APIC.
 * (IO-APICs assumed to be messaging to Pentium local-APICs)
 *
 * the code is designed to be easily extended with new/different
 * interrupt controllers, without having to do assembly magic.
 */

/*
 * Controller mappings for all interrupt sources:
 */
irq_desc_t _irq_desc[NR_IRQS] __cacheline_aligned = {
	[0 ... NR_IRQS-1] = {
		.status = IRQ_DISABLED,
		.handler = &no_irq_type,
		.lock = SPIN_LOCK_UNLOCKED
	}
};

#ifdef CONFIG_SMP
/*
 * This is updated when the user sets irq affinity via /proc
 */
cpumask_t __cacheline_aligned pending_irq_cpumask[NR_IRQS];
static unsigned long pending_irq_redir[BITS_TO_LONGS(NR_IRQS)];
#endif

#ifdef CONFIG_IA64_GENERIC
irq_desc_t * __ia64_irq_desc (unsigned int irq)
{
	return _irq_desc + irq;
}

ia64_vector __ia64_irq_to_vector (unsigned int irq)
{
	return (ia64_vector) irq;
}

unsigned int __ia64_local_vector_to_irq (ia64_vector vec)
{
	return (unsigned int) vec;
}
#endif

static void register_irq_proc (unsigned int irq);

/*
 * Special irq handlers.
 */

irqreturn_t no_action(int cpl, void *dev_id, struct pt_regs *regs)
{ return IRQ_NONE; }

/*
 * Generic no controller code
 */

static void enable_none(unsigned int irq) { }
static unsigned int startup_none(unsigned int irq) { return 0; }
static void disable_none(unsigned int irq) { }
static void ack_none(unsigned int irq)
{
/*
 * 'what should we do if we get a hw irq event on an illegal vector'.
 * each architecture has to answer this themselves, it doesn't deserve
 * a generic callback i think.
 */
#ifdef CONFIG_X86
	printk(KERN_ERR "unexpected IRQ trap at vector %02x\n", irq);
#ifdef CONFIG_X86_LOCAL_APIC
	/*
	 * Currently unexpected vectors happen only on SMP and APIC.
	 * We _must_ ack these because every local APIC has only N
	 * irq slots per priority level, and a 'hanging, unacked' IRQ
	 * holds up an irq slot - in excessive cases (when multiple
	 * unexpected vectors occur) that might lock up the APIC
	 * completely.
	 */
	ack_APIC_irq();
#endif
#endif
#ifdef CONFIG_IA64
	printk(KERN_ERR "Unexpected irq vector 0x%x on CPU %u!\n", irq, smp_processor_id());
#endif
}

/* startup is the same as "enable", shutdown is same as "disable" */
#define shutdown_none	disable_none
#define end_none	enable_none

struct hw_interrupt_type no_irq_type = {
	"none",
	startup_none,
	shutdown_none,
	enable_none,
	disable_none,
	ack_none,
	end_none
};

atomic_t irq_err_count;
#ifdef CONFIG_X86_IO_APIC
#ifdef APIC_MISMATCH_DEBUG
atomic_t irq_mis_count;
#endif
#endif

/*
 * Generic, controller-independent functions:
 */

int show_interrupts(struct seq_file *p, void *v)
{
	int j, i = *(loff_t *) v;
	struct irqaction * action;
	irq_desc_t *idesc;
	unsigned long flags;

	if (i == 0) {
		seq_puts(p, "           ");
		for (j=0; j<NR_CPUS; j++)
			if (cpu_online(j))
				seq_printf(p, "CPU%d       ",j);
		seq_putc(p, '\n');
	}

	if (i < NR_IRQS) {
		idesc = irq_descp(i);
		spin_lock_irqsave(&idesc->lock, flags);
		action = idesc->action;
		if (!action)
			goto skip;
		seq_printf(p, "%3d: ",i);
#ifndef CONFIG_SMP
		seq_printf(p, "%10u ", kstat_irqs(i));
#else
		for (j = 0; j < NR_CPUS; j++)
			if (cpu_online(j))
				seq_printf(p, "%10u ", kstat_cpu(j).irqs[i]);
#endif
		seq_printf(p, " %14s", idesc->handler->typename);
		seq_printf(p, "  %s", action->name);

		for (action=action->next; action; action = action->next)
			seq_printf(p, ", %s", action->name);

		seq_putc(p, '\n');
skip:
		spin_unlock_irqrestore(&idesc->lock, flags);
	} else if (i == NR_IRQS) {
		seq_puts(p, "NMI: ");
		for (j = 0; j < NR_CPUS; j++)
			if (cpu_online(j))
				seq_printf(p, "%10u ", nmi_count(j));
		seq_putc(p, '\n');
#ifdef CONFIG_X86_LOCAL_APIC
		seq_puts(p, "LOC: ");
		for (j = 0; j < NR_CPUS; j++)
			if (cpu_online(j))
				seq_printf(p, "%10u ", irq_stat[j].apic_timer_irqs);
		seq_putc(p, '\n');
#endif
		seq_printf(p, "ERR: %10u\n", atomic_read(&irq_err_count));
#ifdef CONFIG_X86_IO_APIC
#ifdef APIC_MISMATCH_DEBUG
		seq_printf(p, "MIS: %10u\n", atomic_read(&irq_mis_count));
#endif
#endif
	}
	return 0;
}

#ifdef CONFIG_SMP
inline void synchronize_irq(unsigned int irq)
{
	while (irq_descp(irq)->status & IRQ_INPROGRESS)
		cpu_relax();
}
EXPORT_SYMBOL(synchronize_irq);
#endif

/*
 * This should really return information about whether
 * we should do bottom half handling etc. Right now we
 * end up _always_ checking the bottom half, which is a
 * waste of time and is not what some drivers would
 * prefer.
 */
int handle_IRQ_event(unsigned int irq,
		struct pt_regs *regs, struct irqaction *action)
{
	int status = 1;	/* Force the "do bottom halves" bit */
	int ret, retval = 0;

	if (!(action->flags & SA_INTERRUPT))
		local_irq_enable();

	do {
		ret = action->handler(irq, action->dev_id, regs);
		if (ret == IRQ_HANDLED)
			status |= action->flags;
		retval |= ret;
		action = action->next;
	} while (action);
	if (status & SA_SAMPLE_RANDOM)
		add_interrupt_randomness(irq);
	local_irq_disable();
	return retval;
}

static void __report_bad_irq(int irq, irq_desc_t *desc, irqreturn_t action_ret)
{
	struct irqaction *action;

	if (action_ret != IRQ_HANDLED && action_ret != IRQ_NONE) {
		printk(KERN_ERR "irq event %d: bogus return value %x\n",
				irq, action_ret);
	} else {
		printk(KERN_ERR "irq %d: nobody cared!\n", irq);
	}
	dump_stack();
	printk(KERN_ERR "handlers:\n");
	action = desc->action;
	do {
		printk(KERN_ERR "[<%p>]", action->handler);
		print_symbol(" (%s)",
			(unsigned long)action->handler);
		printk("\n");
		action = action->next;
	} while (action);
}

static void report_bad_irq(int irq, irq_desc_t *desc, irqreturn_t action_ret)
{
	static int count = 100;

	if (count) {
		count--;
		__report_bad_irq(irq, desc, action_ret);
	}
}

static int noirqdebug;

static int __init noirqdebug_setup(char *str)
{
	noirqdebug = 1;
	printk("IRQ lockup detection disabled\n");
	return 1;
}

__setup("noirqdebug", noirqdebug_setup);

/*
 * If 99,900 of the previous 100,000 interrupts have not been handled then
 * assume that the IRQ is stuck in some manner.  Drop a diagnostic and try to
 * turn the IRQ off.
 *
 * (The other 100-of-100,000 interrupts may have been a correctly-functioning
 *  device sharing an IRQ with the failing one)
 *
 * Called under desc->lock
 */
static void note_interrupt(int irq, irq_desc_t *desc, irqreturn_t action_ret)
{
	if (action_ret != IRQ_HANDLED) {
		desc->irqs_unhandled++;
		if (action_ret != IRQ_NONE)
			report_bad_irq(irq, desc, action_ret);
	}

	desc->irq_count++;
	if (desc->irq_count < 100000)
		return;

	desc->irq_count = 0;
	if (desc->irqs_unhandled > 99900) {
		/*
		 * The interrupt is stuck
		 */
		__report_bad_irq(irq, desc, action_ret);
		/*
		 * Now kill the IRQ
		 */
		printk(KERN_EMERG "Disabling IRQ #%d\n", irq);
		desc->status |= IRQ_DISABLED;
		desc->handler->disable(irq);
	}
	desc->irqs_unhandled = 0;
}

/*
 * Generic enable/disable code: this just calls
 * down into the PIC-specific version for the actual
 * hardware disable after having gotten the irq
 * controller lock.
 */

/**
 *	disable_irq_nosync - disable an irq without waiting
 *	@irq: Interrupt to disable
 *
 *	Disable the selected interrupt line.  Disables and Enables are
 *	nested.
 *	Unlike disable_irq(), this function does not ensure existing
 *	instances of the IRQ handler have completed before returning.
 *
 *	This function may be called from IRQ context.
 */

inline void disable_irq_nosync(unsigned int irq)
{
	irq_desc_t *desc = irq_descp(irq);
	unsigned long flags;

	spin_lock_irqsave(&desc->lock, flags);
	if (!desc->depth++) {
		desc->status |= IRQ_DISABLED;
		desc->handler->disable(irq);
	}
	spin_unlock_irqrestore(&desc->lock, flags);
}
EXPORT_SYMBOL(disable_irq_nosync);

/**
 *	disable_irq - disable an irq and wait for completion
 *	@irq: Interrupt to disable
 *
 *	Disable the selected interrupt line.  Enables and Disables are
 *	nested.
 *	This function waits for any pending IRQ handlers for this interrupt
 *	to complete before returning. If you use this function while
 *	holding a resource the IRQ handler may need you will deadlock.
 *
 *	This function may be called - with care - from IRQ context.
 */

void disable_irq(unsigned int irq)
{
	irq_desc_t *desc = irq_descp(irq);

	disable_irq_nosync(irq);
	if (desc->action)
		synchronize_irq(irq);
}
EXPORT_SYMBOL(disable_irq);

/**
 *	enable_irq - enable handling of an irq
 *	@irq: Interrupt to enable
 *
 *	Undoes the effect of one call to disable_irq().  If this
 *	matches the last disable, processing of interrupts on this
 *	IRQ line is re-enabled.
 *
 *	This function may be called from IRQ context.
 */

void enable_irq(unsigned int irq)
{
	irq_desc_t *desc = irq_descp(irq);
	unsigned long flags;

	spin_lock_irqsave(&desc->lock, flags);
	switch (desc->depth) {
	case 1: {
		unsigned int status = desc->status & ~IRQ_DISABLED;
		desc->status = status;
		if ((status & (IRQ_PENDING | IRQ_REPLAY)) == IRQ_PENDING) {
			desc->status = status | IRQ_REPLAY;
			hw_resend_irq(desc->handler,irq);
		}
		desc->handler->enable(irq);
		/* fall-through */
	}
	default:
		desc->depth--;
		break;
	case 0:
		printk(KERN_ERR "enable_irq(%u) unbalanced from %p\n",
		       irq, (void *) __builtin_return_address(0));
	}
	spin_unlock_irqrestore(&desc->lock, flags);
}
EXPORT_SYMBOL(enable_irq);

/*
 * do_IRQ handles all normal device IRQ's (the special
 * SMP cross-CPU interrupts have their own specific
 * handlers).
 */
unsigned int do_IRQ(unsigned long irq, struct pt_regs *regs)
{
	/*
	 * We ack quickly, we don't want the irq controller
	 * thinking we're snobs just because some other CPU has
	 * disabled global interrupts (we have already done the
	 * INT_ACK cycles, it's too late to try to pretend to the
	 * controller that we aren't taking the interrupt).
	 *
	 * 0 return value means that this irq is already being
	 * handled by some other CPU. (or is disabled)
	 */
	irq_desc_t *desc = irq_descp(irq);
	struct irqaction * action;
	irqreturn_t action_ret;
	unsigned int status;
	int cpu;

	cpu = smp_processor_id(); /* for CONFIG_PREEMPT, this must come after irq_enter()! */

	kstat_cpu(cpu).irqs[irq]++;

	if (desc->status & IRQ_PER_CPU) {
		/* no locking required for CPU-local interrupts: */
		desc->handler->ack(irq);
		action_ret = handle_IRQ_event(irq, regs, desc->action);
		desc->handler->end(irq);
	} else {
		spin_lock(&desc->lock);
		desc->handler->ack(irq);
		/*
		 * REPLAY is when Linux resends an IRQ that was dropped earlier
		 * WAITING is used by probe to mark irqs that are being tested
		 */
		status = desc->status & ~(IRQ_REPLAY | IRQ_WAITING);
		status |= IRQ_PENDING; /* we _want_ to handle it */

		/*
		 * If the IRQ is disabled for whatever reason, we cannot
		 * use the action we have.
		 */
		action = NULL;
		if (likely(!(status & (IRQ_DISABLED | IRQ_INPROGRESS)))) {
			action = desc->action;
			status &= ~IRQ_PENDING; /* we commit to handling */
			status |= IRQ_INPROGRESS; /* we are handling it */
		}
		desc->status = status;

		/*
		 * If there is no IRQ handler or it was disabled, exit early.
		 * Since we set PENDING, if another processor is handling
		 * a different instance of this same irq, the other processor
		 * will take care of it.
		 */
		if (unlikely(!action))
			goto out;

		/*
		 * Edge triggered interrupts need to remember
		 * pending events.
		 * This applies to any hw interrupts that allow a second
		 * instance of the same irq to arrive while we are in do_IRQ
		 * or in the handler. But the code here only handles the _second_
		 * instance of the irq, not the third or fourth. So it is mostly
		 * useful for irq hardware that does not mask cleanly in an
		 * SMP environment.
		 */
		for (;;) {
			spin_unlock(&desc->lock);
			action_ret = handle_IRQ_event(irq, regs, action);
			spin_lock(&desc->lock);
			if (!noirqdebug)
				note_interrupt(irq, desc, action_ret);
			if (!(desc->status & IRQ_PENDING))
				break;
			desc->status &= ~IRQ_PENDING;
		}
		desc->status &= ~IRQ_INPROGRESS;
	  out:
		/*
		 * The ->end() handler has to deal with interrupts which got
		 * disabled while the handler was running.
		 */
		desc->handler->end(irq);
		spin_unlock(&desc->lock);
	}
	return 1;
}

/**
 *	request_irq - allocate an interrupt line
 *	@irq: Interrupt line to allocate
 *	@handler: Function to be called when the IRQ occurs
 *	@irqflags: Interrupt type flags
 *	@devname: An ascii name for the claiming device
 *	@dev_id: A cookie passed back to the handler function
 *
 *	This call allocates interrupt resources and enables the
 *	interrupt line and IRQ handling. From the point this
 *	call is made your handler function may be invoked. Since
 *	your handler function must clear any interrupt the board 
 *	raises, you must take care both to initialise your hardware
 *	and to set up the interrupt handler in the right order.
 *
 *	Dev_id must be globally unique. Normally the address of the
 *	device data structure is used as the cookie. Since the handler
 *	receives this value it makes sense to use it.
 *
 *	If your interrupt is shared you must pass a non NULL dev_id
 *	as this is required when freeing the interrupt.
 *
 *	Flags:
 *
 *	SA_SHIRQ		Interrupt is shared
 *
 *	SA_INTERRUPT		Disable local interrupts while processing
 *
 *	SA_SAMPLE_RANDOM	The interrupt can be used for entropy
 *
 */

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

#if 1
	/*
	 * Sanity-check: shared interrupts should REALLY pass in
	 * a real dev-ID, otherwise we'll have trouble later trying
	 * to figure out which interrupt is which (messes up the
	 * interrupt freeing logic etc).
	 */
	if (irqflags & SA_SHIRQ) {
		if (!dev_id)
			printk(KERN_ERR "Bad boy: %s called us without a dev_id!\n", devname);