/*
 * 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>

#include "internals.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);
static int irq_poll_cpu;
static atomic_t irq_poll_active;

/*
 * We wait here for a poller to finish.
 *
 * If the poll runs on this CPU, then we yell loudly and return
 * false. That will leave the interrupt line disabled in the worst
 * case, but it should never happen.
 *
 * We wait until the poller is done and then recheck disabled and
 * action (about to be disabled). Only if it's still active, we return
 * true and let the handler run.
 */
bool irq_wait_for_poll(struct irq_desc *desc)
{
        if (WARN_ONCE(irq_poll_cpu == smp_processor_id(),
                      "irq poll in progress on cpu %d for irq %d\n",
                      smp_processor_id(), desc->irq_data.irq))
                return false;

#ifdef CONFIG_SMP
        do {
                raw_spin_unlock(&desc->lock);
                while (irqd_irq_inprogress(&desc->irq_data))
                        cpu_relax();
                raw_spin_lock(&desc->lock);
        } while (irqd_irq_inprogress(&desc->irq_data));
        /* Might have been disabled in meantime */
        return !irqd_irq_disabled(&desc->irq_data) && desc->action;
#else
        return false;
#endif
}


/*
 * Recovery handler for misrouted interrupts.
 */
static int try_one_irq(int irq, struct irq_desc *desc, bool force)
{
        irqreturn_t ret = IRQ_NONE;
        struct irqaction *action;

        raw_spin_lock(&desc->lock);

        /* PER_CPU and nested thread interrupts are never polled */
        if (irq_settings_is_per_cpu(desc) || irq_settings_is_nested_thread(desc))
                goto out;

        /*
         * Do not poll disabled interrupts unless the spurious
         * disabled poller asks explicitely.
         */
        if (irqd_irq_disabled(&desc->irq_data) && !force)
                goto out;

        /*
         * All handlers must agree on IRQF_SHARED, so we test just the
         * first. Check for action->next as well.
         */
        action = desc->action;
        if (!action || !(action->flags & IRQF_SHARED) ||
            (action->flags & __IRQF_TIMER) ||
            (action->handler(irq, action->dev_id) == IRQ_HANDLED) ||
            !action->next)
                goto out;

        /* Already running on another processor */
        if (irqd_irq_inprogress(&desc->irq_data)) {
                /*
                 * Already running: If it is shared get the other
                 * CPU to go looking for our mystery interrupt too
                 */
                desc->istate |= IRQS_PENDING;
                goto out;
        }

        /* Mark it poll in progress */
        desc->istate |= IRQS_POLL_INPROGRESS;
        do {
                if (handle_irq_event(desc) == IRQ_HANDLED)
                        ret = IRQ_HANDLED;
                action = desc->action;
        } while ((desc->istate & IRQS_PENDING) && action);
        desc->istate &= ~IRQS_POLL_INPROGRESS;
out:
        raw_spin_unlock(&desc->lock);
        return ret == IRQ_HANDLED;
}

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

        if (atomic_inc_return(&irq_poll_active) != 1)
                goto out;

        irq_poll_cpu = smp_processor_id();

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

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

                if (try_one_irq(i, desc, false))
                        ok = 1;
        }
out:
        atomic_dec(&irq_poll_active);
        /* So the caller can adjust the irq error counts */
        return ok;
}

static void poll_spurious_irqs(unsigned long dummy)
{
        struct irq_desc *desc;
        int i;

        if (atomic_inc_return(&irq_poll_active) != 1)
                goto out;
        irq_poll_cpu = smp_processor_id();

        for_each_irq_desc(i, desc) {
                unsigned int state;

                if (!i)
                         continue;

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

                local_irq_disable();
                try_one_irq(i, desc, true);
                local_irq_enable();
        }
out:
        atomic_dec(&irq_poll_active);
        mod_timer(&poll_spurious_irq_timer,
                  jiffies + POLL_SPURIOUS_IRQ_INTERVAL);
}

static inline int bad_action_ret(irqreturn_t action_ret)
{
        if (likely(action_ret <= (IRQ_HANDLED | IRQ_WAKE_THREAD)))
                return 0;
        return 1;
}

/*
 * 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)
 */
static void
__report_bad_irq(unsigned int irq, struct irq_desc *desc,
                 irqreturn_t action_ret)
{
        struct irqaction *action;
        unsigned long flags;

        if (bad_action_ret(action_ret)) {
                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");

        /*
         * We need to take desc->lock here. note_interrupt() is called
         * w/o desc->lock held, but IRQ_PROGRESS set. We might race
         * with something else removing an action. It's ok to take
         * desc->lock here. See synchronize_irq().
         */
        raw_spin_lock_irqsave(&desc->lock, flags);
        action = desc->action;
        while (action) {
                printk(KERN_ERR "[<%p>] %pf", action->handler, action->handler);
                if (action->thread_fn)
                        printk(KERN_CONT " threaded [<%p>] %pf",
                                        action->thread_fn, action->thread_fn);
                printk(KERN_CONT "\n");
                action = action->next;
        }
        raw_spin_unlock_irqrestore(&desc->lock, flags);
}

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 (desc->istate & IRQS_POLL_INPROGRESS)
                return;

        /* we get here again via the threaded handler */
        if (action_ret == IRQ_WAKE_THREAD)
                return;

        if (bad_action_ret(action_ret)) {
                report_bad_irq(irq, desc, action_ret);
                return;
        }

        if (unlikely(action_ret == IRQ_NONE)) {
                /*
                 * If we are seeing only the odd spurious IRQ caused by
                 * bus asynchronicity then don't eventually trigger an error,
                 * otherwise the counter 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(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->istate |= IRQS_SPURIOUS_DISABLED;
                desc->depth++;
                irq_disable(desc);

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

bool 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);