sparseirq: work around __weak alias bug

[linux-2.6/btrfs-unstable.git] / kernel / irq / handle.c

/*
 * linux/kernel/irq/handle.c
 *
 * Copyright (C) 1992, 1998-2006 Linus Torvalds, Ingo Molnar
 * Copyright (C) 2005-2006, Thomas Gleixner, Russell King
 *
 * This file contains the core interrupt handling code.
 *
 * Detailed information is available in Documentation/DocBook/genericirq
 *
 */

#include <linux/irq.h>
#include <linux/module.h>
#include <linux/random.h>
#include <linux/interrupt.h>
#include <linux/kernel_stat.h>
#include <linux/rculist.h>
#include <linux/hash.h>

#include "internals.h"

/*
 * lockdep: we want to handle all irq_desc locks as a single lock-class:
 */
struct lock_class_key irq_desc_lock_class;

/**
 * handle_bad_irq - handle spurious and unhandled irqs
 * @irq:       the interrupt number
 * @desc:      description of the interrupt
 *
 * Handles spurious and unhandled IRQ's. It also prints a debugmessage.
 */
void handle_bad_irq(unsigned int irq, struct irq_desc *desc)
{
        print_irq_desc(irq, desc);
        kstat_incr_irqs_this_cpu(irq, desc);
        ack_bad_irq(irq);
}

/*
 * Linux has a controller-independent 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.
 *
 * The code is designed to be easily extended with new/different
 * interrupt controllers, without having to do assembly magic or
 * having to touch the generic code.
 *
 * Controller mappings for all interrupt sources:
 */
int nr_irqs = NR_IRQS;
EXPORT_SYMBOL_GPL(nr_irqs);

#ifdef CONFIG_SPARSE_IRQ
static struct irq_desc irq_desc_init = {
        .irq        = -1,
        .status     = IRQ_DISABLED,
        .chip       = &no_irq_chip,
        .handle_irq = handle_bad_irq,
        .depth      = 1,
        .lock       = __SPIN_LOCK_UNLOCKED(irq_desc_init.lock),
#ifdef CONFIG_SMP
        .affinity   = CPU_MASK_ALL
#endif
};

void init_kstat_irqs(struct irq_desc *desc, int cpu, int nr)
{
        unsigned long bytes;
        char *ptr;
        int node;

        /* Compute how many bytes we need per irq and allocate them */
        bytes = nr * sizeof(unsigned int);

        node = cpu_to_node(cpu);
        ptr = kzalloc_node(bytes, GFP_ATOMIC, node);
        printk(KERN_DEBUG "  alloc kstat_irqs on cpu %d node %d\n", cpu, node);

        if (ptr)
                desc->kstat_irqs = (unsigned int *)ptr;
}

static void init_one_irq_desc(int irq, struct irq_desc *desc, int cpu)
{
        memcpy(desc, &irq_desc_init, sizeof(struct irq_desc));

        spin_lock_init(&desc->lock);
        desc->irq = irq;
#ifdef CONFIG_SMP
        desc->cpu = cpu;
#endif
        lockdep_set_class(&desc->lock, &irq_desc_lock_class);
        init_kstat_irqs(desc, cpu, nr_cpu_ids);
        if (!desc->kstat_irqs) {
                printk(KERN_ERR "can not alloc kstat_irqs\n");
                BUG_ON(1);
        }
        arch_init_chip_data(desc, cpu);
}

/*
 * Protect the sparse_irqs:
 */
DEFINE_SPINLOCK(sparse_irq_lock);

struct irq_desc *irq_desc_ptrs[NR_IRQS] __read_mostly;

static struct irq_desc irq_desc_legacy[NR_IRQS_LEGACY] __cacheline_aligned_in_smp = {
        [0 ... NR_IRQS_LEGACY-1] = {
                .irq        = -1,
                .status     = IRQ_DISABLED,
                .chip       = &no_irq_chip,
                .handle_irq = handle_bad_irq,
                .depth      = 1,
                .lock       = __SPIN_LOCK_UNLOCKED(irq_desc_init.lock),
#ifdef CONFIG_SMP
                .affinity   = CPU_MASK_ALL
#endif
        }
};

/* FIXME: use bootmem alloc ...*/
static unsigned int kstat_irqs_legacy[NR_IRQS_LEGACY][NR_CPUS];

int __init early_irq_init(void)
{
        struct irq_desc *desc;
        int legacy_count;
        int i;

        desc = irq_desc_legacy;
        legacy_count = ARRAY_SIZE(irq_desc_legacy);

        for (i = 0; i < legacy_count; i++) {
                desc[i].irq = i;
                desc[i].kstat_irqs = kstat_irqs_legacy[i];
                lockdep_set_class(&desc[i].lock, &irq_desc_lock_class);

                irq_desc_ptrs[i] = desc + i;
        }

        for (i = legacy_count; i < NR_IRQS; i++)
                irq_desc_ptrs[i] = NULL;

        return arch_early_irq_init();
}

struct irq_desc *irq_to_desc(unsigned int irq)
{
        return (irq < NR_IRQS) ? irq_desc_ptrs[irq] : NULL;
}

struct irq_desc *irq_to_desc_alloc_cpu(unsigned int irq, int cpu)
{
        struct irq_desc *desc;
        unsigned long flags;
        int node;

        if (irq >= NR_IRQS) {
                printk(KERN_WARNING "irq >= NR_IRQS in irq_to_desc_alloc: %d %d\n",
                                irq, NR_IRQS);
                WARN_ON(1);
                return NULL;
        }

        desc = irq_desc_ptrs[irq];
        if (desc)
                return desc;

        spin_lock_irqsave(&sparse_irq_lock, flags);

        /* We have to check it to avoid races with another CPU */
        desc = irq_desc_ptrs[irq];
        if (desc)
                goto out_unlock;

        node = cpu_to_node(cpu);
        desc = kzalloc_node(sizeof(*desc), GFP_ATOMIC, node);
        printk(KERN_DEBUG "  alloc irq_desc for %d on cpu %d node %d\n",
                 irq, cpu, node);
        if (!desc) {
                printk(KERN_ERR "can not alloc irq_desc\n");
                BUG_ON(1);
        }
        init_one_irq_desc(irq, desc, cpu);

        irq_desc_ptrs[irq] = desc;

out_unlock:
        spin_unlock_irqrestore(&sparse_irq_lock, flags);

        return desc;
}

#else /* !CONFIG_SPARSE_IRQ */

struct irq_desc irq_desc[NR_IRQS] __cacheline_aligned_in_smp = {
        [0 ... NR_IRQS-1] = {
                .status = IRQ_DISABLED,
                .chip = &no_irq_chip,
                .handle_irq = handle_bad_irq,
                .depth = 1,
                .lock = __SPIN_LOCK_UNLOCKED(irq_desc->lock),
#ifdef CONFIG_SMP
                .affinity = CPU_MASK_ALL
#endif
        }
};

int __init early_irq_init(void)
{
        struct irq_desc *desc;
        int count;
        int i;

        desc = irq_desc;
        count = ARRAY_SIZE(irq_desc);

        for (i = 0; i < count; i++)
                desc[i].irq = i;

        return arch_early_irq_init();
}

struct irq_desc *irq_to_desc(unsigned int irq)
{
        return (irq < NR_IRQS) ? irq_desc + irq : NULL;
}

struct irq_desc *irq_to_desc_alloc_cpu(unsigned int irq, int cpu)
{
        return irq_to_desc(irq);
}
#endif /* !CONFIG_SPARSE_IRQ */

/*
 * What should we do if we get a hw irq event on an illegal vector?
 * Each architecture has to answer this themself.
 */
static void ack_bad(unsigned int irq)
{
        struct irq_desc *desc = irq_to_desc(irq);

        print_irq_desc(irq, desc);
        ack_bad_irq(irq);
}

/*
 * NOP functions
 */
static void noop(unsigned int irq)
{
}

static unsigned int noop_ret(unsigned int irq)
{
        return 0;
}

/*
 * Generic no controller implementation
 */
struct irq_chip no_irq_chip = {
        .name           = "none",
        .startup        = noop_ret,
        .shutdown       = noop,
        .enable         = noop,
        .disable        = noop,
        .ack            = ack_bad,
        .end            = noop,
};

/*
 * Generic dummy implementation which can be used for
 * real dumb interrupt sources
 */
struct irq_chip dummy_irq_chip = {
        .name           = "dummy",
        .startup        = noop_ret,
        .shutdown       = noop,
        .enable         = noop,
        .disable        = noop,
        .ack            = noop,
        .mask           = noop,
        .unmask         = noop,
        .end            = noop,
};

/*
 * Special, empty irq handler:
 */
irqreturn_t no_action(int cpl, void *dev_id)
{
        return IRQ_NONE;
}

/**
 * handle_IRQ_event - irq action chain handler
 * @irq:        the interrupt number
 * @action:     the interrupt action chain for this irq
 *
 * Handles the action chain of an irq event
 */
irqreturn_t handle_IRQ_event(unsigned int irq, struct irqaction *action)
{
        irqreturn_t ret, retval = IRQ_NONE;
        unsigned int status = 0;

        if (!(action->flags & IRQF_DISABLED))
                local_irq_enable_in_hardirq();

        do {
                ret = action->handler(irq, action->dev_id);
                if (ret == IRQ_HANDLED)
                        status |= action->flags;
                retval |= ret;
                action = action->next;
        } while (action);

        if (status & IRQF_SAMPLE_RANDOM)
                add_interrupt_randomness(irq);
        local_irq_disable();

        return retval;
}

#ifndef CONFIG_GENERIC_HARDIRQS_NO__DO_IRQ
/**
 * __do_IRQ - original all in one highlevel IRQ handler
 * @irq:        the interrupt number
 *
 * __do_IRQ handles all normal device IRQ's (the special
 * SMP cross-CPU interrupts have their own specific
 * handlers).
 *
 * This is the original x86 implementation which is used for every
 * interrupt type.
 */
unsigned int __do_IRQ(unsigned int irq)
{
        struct irq_desc *desc = irq_to_desc(irq);
        struct irqaction *action;
        unsigned int status;

        kstat_incr_irqs_this_cpu(irq, desc);

        if (CHECK_IRQ_PER_CPU(desc->status)) {
                irqreturn_t action_ret;

                /*
                 * No locking required for CPU-local interrupts:
                 */
                if (desc->chip->ack) {
                        desc->chip->ack(irq);
                        /* get new one */
                        desc = irq_remap_to_desc(irq, desc);
                }
                if (likely(!(desc->status & IRQ_DISABLED))) {
                        action_ret = handle_IRQ_event(irq, desc->action);
                        if (!noirqdebug)
                                note_interrupt(irq, desc, action_ret);
                }
                desc->chip->end(irq);
                return 1;
        }

        spin_lock(&desc->lock);
        if (desc->chip->ack) {
                desc->chip->ack(irq);
                desc = irq_remap_to_desc(irq, desc);
        }
        /*
         * 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 (;;) {
                irqreturn_t action_ret;

                spin_unlock(&desc->lock);

                action_ret = handle_IRQ_event(irq, action);
                if (!noirqdebug)
                        note_interrupt(irq, desc, action_ret);

                spin_lock(&desc->lock);
                if (likely(!(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->chip->end(irq);
        spin_unlock(&desc->lock);

        return 1;
}
#endif

void early_init_irq_lock_class(void)
{
        struct irq_desc *desc;
        int i;

        for_each_irq_desc(i, desc) {
                lockdep_set_class(&desc->lock, &irq_desc_lock_class);
        }
}

#ifdef CONFIG_SPARSE_IRQ
unsigned int kstat_irqs_cpu(unsigned int irq, int cpu)
{
        struct irq_desc *desc = irq_to_desc(irq);
        return desc ? desc->kstat_irqs[cpu] : 0;
}
#endif
EXPORT_SYMBOL(kstat_irqs_cpu);