/*
 * linux/kernel/irq/spurious.c
 *
 * Copyright (C) 1992, 1998-2004 Linus Torvalds, Ingo Molnar
 *
 * This file contains spurious interrupt handling.
 */

#include <linux/jiffies.h>
#include <linux/irq.h>
#include <linux/module.h>
#include <linux/kallsyms.h>
#include <linux/interrupt.h>
#include <linux/moduleparam.h>
#include <linux/timer.h>

static int irqfixup __read_mostly;

#define POLL_SPURIOUS_IRQ_INTERVAL (HZ/10)
static void poll_spurious_irqs(unsigned long dummy);
static DEFINE_TIMER(poll_spurious_irq_timer, poll_spurious_irqs, 0, 0);

/*
 * Recovery handler for misrouted interrupts.
 */
static int try_one_irq(int irq, struct irq_desc *desc)
{
        struct irqaction *action;
        int ok = 0, work = 0;

        spin_lock(&desc->lock);
        /* Already running on another processor */
        if (desc->status & IRQ_INPROGRESS) {
                /*
                 * Already running: If it is shared get the other
                 * CPU to go looking for our mystery interrupt too
                 */
                if (desc->action && (desc->action->flags & IRQF_SHARED))
                        desc->status |= IRQ_PENDING;
                spin_unlock(&desc->lock);
                return ok;
        }
        /* Honour the normal IRQ locking */
        desc->status |= IRQ_INPROGRESS;
        action = desc->action;
        spin_unlock(&desc->lock);

        while (action) {
                /* Only shared IRQ handlers are safe to call */
                if (action->flags & IRQF_SHARED) {
                        if (action->handler(irq, action->dev_id) ==
                                IRQ_HANDLED)
                                ok = 1;
                }
                action = action->next;
        }
        local_irq_disable();
        /* Now clean up the flags */
        spin_lock(&desc->lock);
        action = desc->action;

        /*
         * While we were looking for a fixup someone queued a real
         * IRQ clashing with our walk:
         */
        while ((desc->status & IRQ_PENDING) && action) {
                /*
                 * Perform real IRQ processing for the IRQ we deferred
                 */
                work = 1;
                spin_unlock(&desc->lock);
                handle_IRQ_event(irq, action);
                spin_lock(&desc->lock);
                desc->status &= ~IRQ_PENDING;
        }
        desc->status &= ~IRQ_INPROGRESS;
        /*
         * If we did actual work for the real IRQ line we must let the
         * IRQ controller clean up too
         */
        if (work && desc->chip && desc->chip->end)
                desc->chip->end(irq);
        spin_unlock(&desc->lock);

        return ok;
}

static int misrouted_irq(int irq)
{
        struct irq_desc *desc;
        int i, ok = 0;

        for_each_irq_desc(i, desc) {
                if (!i)
                         continue;

                if (i == irq)   /* Already tried */
                        continue;

                if (try_one_irq(i, desc))
                        ok = 1;
        }
        /* So the caller can adjust the irq error counts */
        return ok;
}

static void poll_all_shared_irqs(void)
{
        struct irq_desc *desc;
        int i;

        for_each_irq_desc(i, desc) {
                unsigned int status;

                if (!i)
                         continue;

                /* Racy but it doesn't matter */
                status = desc->status;
                barrier();
                if (!(status & IRQ_SPURIOUS_DISABLED))
                        continue;

                local_irq_disable();
                try_one_irq(i, desc);
                local_irq_enable();
        }
}

static void poll_spurious_irqs(unsigned long dummy)
{
        poll_all_shared_irqs();

        mod_timer(&poll_spurious_irq_timer,
                  jiffies + POLL_SPURIOUS_IRQ_INTERVAL);
}

#ifdef CONFIG_DEBUG_SHIRQ
void debug_poll_all_shared_irqs(void)
{
        poll_all_shared_irqs();
}
#endif

/*
 * 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
__report_bad_irq(unsigned int irq, struct irq_desc *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 (try booting with "
                                "the \"irqpoll\" option)\n", irq);
        }
        dump_stack();
        printk(KERN_ERR "handlers:\n");

        action = desc->action;
        while (action) {
                printk(KERN_ERR "[<%p>]", action->handler);
                print_symbol(" (%s)",
                        (unsigned long)action->handler);
                printk("\n");
                action = action->next;
        }
}

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

        if (count > 0) {
                count--;
                __report_bad_irq(irq, desc, action_ret);
        }
}

static inline int
try_misrouted_irq(unsigned int irq, struct irq_desc *desc,
                  irqreturn_t action_ret)
{
        struct irqaction *action;

        if (!irqfixup)
                return 0;

        /* We didn't actually handle the IRQ - see if it was misrouted? */
        if (action_ret == IRQ_NONE)
                return 1;

        /*
         * But for 'irqfixup == 2' we also do it for handled interrupts if
         * they are marked as IRQF_IRQPOLL (or for irq zero, which is the
         * traditional PC timer interrupt.. Legacy)
         */
        if (irqfixup < 2)
                return 0;

        if (!irq)
                return 1;

        /*
         * Since we don't get the descriptor lock, "action" can
         * change under us.  We don't really care, but we don't
         * want to follow a NULL pointer. So tell the compiler to
         * just load it once by using a barrier.
         */
        action = desc->action;
        barrier();
        return action && (action->flags & IRQF_IRQPOLL);
}

void note_interrupt(unsigned int irq, struct irq_desc *desc,
                    irqreturn_t action_ret)
{
        if (unlikely(action_ret != IRQ_HANDLED)) {
                /*
                 * If we are seeing only the odd spurious IRQ caused by
                 * bus asynchronicity then don't eventually trigger an error,
                 * otherwise the couter becomes a doomsday timer for otherwise
                 * working systems
                 */
                if (time_after(jiffies, desc->last_unhandled + HZ/10))
                        desc->irqs_unhandled = 1;
                else
                        desc->irqs_unhandled++;
                desc->last_unhandled = jiffies;
                if (unlikely(action_ret != IRQ_NONE))
                        report_bad_irq(irq, desc, action_ret);
        }

        if (unlikely(try_misrouted_irq(irq, desc, action_ret))) {
                int ok = misrouted_irq(irq);
                if (action_ret == IRQ_NONE)
                        desc->irqs_unhandled -= ok;
        }

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

        desc->irq_count = 0;
        if (unlikely(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 | IRQ_SPURIOUS_DISABLED;
                desc->depth++;
                desc->chip->disable(irq);

                mod_timer(&poll_spurious_irq_timer,
                          jiffies + POLL_SPURIOUS_IRQ_INTERVAL);
        }
        desc->irqs_unhandled = 0;
}

int noirqdebug __read_mostly;

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

        return 1;
}

__setup("noirqdebug", noirqdebug_setup);
module_param(noirqdebug, bool, 0644);
MODULE_PARM_DESC(noirqdebug, "Disable irq lockup detection when true");

static int __init irqfixup_setup(char *str)
{
        irqfixup = 1;
        printk(KERN_WARNING "Misrouted IRQ fixup support enabled.\n");
        printk(KERN_WARNING "This may impact system performance.\n");

        return 1;
}

__setup("irqfixup", irqfixup_setup);
module_param(irqfixup, int, 0644);

static int __init irqpoll_setup(char *str)
{
        irqfixup = 2;
        printk(KERN_WARNING "Misrouted IRQ fixup and polling support "
                                "enabled\n");
        printk(KERN_WARNING "This may significantly impact system "
                                "performance\n");
        return 1;
}

__setup("irqpoll", irqpoll_setup);