sched: make early bootup sched_clock() use safer

[wrt350n-kernel.git] / kernel / irq / manage.c

/*
 * linux/kernel/irq/manage.c
 *
 * Copyright (C) 1992, 1998-2006 Linus Torvalds, Ingo Molnar
 * Copyright (C) 2005-2006 Thomas Gleixner
 *
 * This file contains driver APIs to the irq subsystem.
 */

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

#include "internals.h"

#ifdef CONFIG_SMP

/**
 *      synchronize_irq - wait for pending IRQ handlers (on other CPUs)
 *      @irq: interrupt number to wait for
 *
 *      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 synchronize_irq(unsigned int irq)
{
        struct irq_desc *desc = irq_desc + irq;
        unsigned int status;

        if (irq >= NR_IRQS)
                return;

        do {
                unsigned long flags;

                /*
                 * Wait until we're out of the critical section.  This might
                 * give the wrong answer due to the lack of memory barriers.
                 */
                while (desc->status & IRQ_INPROGRESS)
                        cpu_relax();

                /* Ok, that indicated we're done: double-check carefully. */
                spin_lock_irqsave(&desc->lock, flags);
                status = desc->status;
                spin_unlock_irqrestore(&desc->lock, flags);

                /* Oops, that failed? */
        } while (status & IRQ_INPROGRESS);
}
EXPORT_SYMBOL(synchronize_irq);

/**
 *      irq_can_set_affinity - Check if the affinity of a given irq can be set
 *      @irq:           Interrupt to check
 *
 */
int irq_can_set_affinity(unsigned int irq)
{
        struct irq_desc *desc = irq_desc + irq;

        if (CHECK_IRQ_PER_CPU(desc->status) || !desc->chip ||
            !desc->chip->set_affinity)
                return 0;

        return 1;
}

/**
 *      irq_set_affinity - Set the irq affinity of a given irq
 *      @irq:           Interrupt to set affinity
 *      @cpumask:       cpumask
 *
 */
int irq_set_affinity(unsigned int irq, cpumask_t cpumask)
{
        struct irq_desc *desc = irq_desc + irq;

        if (!desc->chip->set_affinity)
                return -EINVAL;

        set_balance_irq_affinity(irq, cpumask);

#ifdef CONFIG_GENERIC_PENDING_IRQ
        set_pending_irq(irq, cpumask);
#else
        desc->affinity = cpumask;
        desc->chip->set_affinity(irq, cpumask);
#endif
        return 0;
}

#endif

/**
 *      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.
 */
void disable_irq_nosync(unsigned int irq)
{
        struct irq_desc *desc = irq_desc + irq;
        unsigned long flags;

        if (irq >= NR_IRQS)
                return;

        spin_lock_irqsave(&desc->lock, flags);
        if (!desc->depth++) {
                desc->status |= IRQ_DISABLED;
                desc->chip->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)
{
        struct irq_desc *desc = irq_desc + irq;

        if (irq >= NR_IRQS)
                return;

        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)
{
        struct irq_desc *desc = irq_desc + irq;
        unsigned long flags;

        if (irq >= NR_IRQS)
                return;

        spin_lock_irqsave(&desc->lock, flags);
        switch (desc->depth) {
        case 0:
                printk(KERN_WARNING "Unbalanced enable for IRQ %d\n", irq);
                WARN_ON(1);
                break;
        case 1: {
                unsigned int status = desc->status & ~IRQ_DISABLED;

                /* Prevent probing on this irq: */
                desc->status = status | IRQ_NOPROBE;
                check_irq_resend(desc, irq);
                /* fall-through */
        }
        default:
                desc->depth--;
        }
        spin_unlock_irqrestore(&desc->lock, flags);
}
EXPORT_SYMBOL(enable_irq);

/**
 *      set_irq_wake - control irq power management wakeup
 *      @irq:   interrupt to control
 *      @on:    enable/disable power management wakeup
 *
 *      Enable/disable power management wakeup mode, which is
 *      disabled by default.  Enables and disables must match,
 *      just as they match for non-wakeup mode support.
 *
 *      Wakeup mode lets this IRQ wake the system from sleep
 *      states like "suspend to RAM".
 */
int set_irq_wake(unsigned int irq, unsigned int on)
{
        struct irq_desc *desc = irq_desc + irq;
        unsigned long flags;
        int ret = -ENXIO;
        int (*set_wake)(unsigned, unsigned) = desc->chip->set_wake;

        /* wakeup-capable irqs can be shared between drivers that
         * don't need to have the same sleep mode behaviors.
         */
        spin_lock_irqsave(&desc->lock, flags);
        if (on) {
                if (desc->wake_depth++ == 0)
                        desc->status |= IRQ_WAKEUP;
                else
                        set_wake = NULL;
        } else {
                if (desc->wake_depth == 0) {
                        printk(KERN_WARNING "Unbalanced IRQ %d "
                                        "wake disable\n", irq);
                        WARN_ON(1);
                } else if (--desc->wake_depth == 0)
                        desc->status &= ~IRQ_WAKEUP;
                else
                        set_wake = NULL;
        }
        if (set_wake)
                ret = desc->chip->set_wake(irq, on);
        spin_unlock_irqrestore(&desc->lock, flags);
        return ret;
}
EXPORT_SYMBOL(set_irq_wake);

/*
 * Internal function that tells the architecture code whether a
 * particular irq has been exclusively allocated or is available
 * for driver use.
 */
int can_request_irq(unsigned int irq, unsigned long irqflags)
{
        struct irqaction *action;

        if (irq >= NR_IRQS || irq_desc[irq].status & IRQ_NOREQUEST)
                return 0;

        action = irq_desc[irq].action;
        if (action)
                if (irqflags & action->flags & IRQF_SHARED)
                        action = NULL;

        return !action;
}

void compat_irq_chip_set_default_handler(struct irq_desc *desc)
{
        /*
         * If the architecture still has not overriden
         * the flow handler then zap the default. This
         * should catch incorrect flow-type setting.
         */
        if (desc->handle_irq == &handle_bad_irq)
                desc->handle_irq = NULL;
}

/*
 * Internal function to register an irqaction - typically used to
 * allocate special interrupts that are part of the architecture.
 */
int setup_irq(unsigned int irq, struct irqaction *new)
{
        struct irq_desc *desc = irq_desc + irq;
        struct irqaction *old, **p;
        const char *old_name = NULL;
        unsigned long flags;
        int shared = 0;

        if (irq >= NR_IRQS)
                return -EINVAL;

        if (desc->chip == &no_irq_chip)
                return -ENOSYS;
        /*
         * Some drivers like serial.c use request_irq() heavily,
         * so we have to be careful not to interfere with a
         * running system.
         */
        if (new->flags & IRQF_SAMPLE_RANDOM) {
                /*
                 * This function might sleep, we want to call it first,
                 * outside of the atomic block.
                 * Yes, this might clear the entropy pool if the wrong
                 * driver is attempted to be loaded, without actually
                 * installing a new handler, but is this really a problem,
                 * only the sysadmin is able to do this.
                 */
                rand_initialize_irq(irq);
        }

        /*
         * The following block of code has to be executed atomically
         */
        spin_lock_irqsave(&desc->lock, flags);
        p = &desc->action;
        old = *p;
        if (old) {
                /*
                 * Can't share interrupts unless both agree to and are
                 * the same type (level, edge, polarity). So both flag
                 * fields must have IRQF_SHARED set and the bits which
                 * set the trigger type must match.
                 */
                if (!((old->flags & new->flags) & IRQF_SHARED) ||
                    ((old->flags ^ new->flags) & IRQF_TRIGGER_MASK)) {
                        old_name = old->name;
                        goto mismatch;
                }

#if defined(CONFIG_IRQ_PER_CPU)
                /* All handlers must agree on per-cpuness */
                if ((old->flags & IRQF_PERCPU) !=
                    (new->flags & IRQF_PERCPU))
                        goto mismatch;
#endif

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

        *p = new;

        /* Exclude IRQ from balancing */
        if (new->flags & IRQF_NOBALANCING)
                desc->status |= IRQ_NO_BALANCING;

        if (!shared) {
                irq_chip_set_defaults(desc->chip);

#if defined(CONFIG_IRQ_PER_CPU)
                if (new->flags & IRQF_PERCPU)
                        desc->status |= IRQ_PER_CPU;
#endif

                /* Setup the type (level, edge polarity) if configured: */
                if (new->flags & IRQF_TRIGGER_MASK) {
                        if (desc->chip && desc->chip->set_type)
                                desc->chip->set_type(irq,
                                                new->flags & IRQF_TRIGGER_MASK);
                        else
                                /*
                                 * IRQF_TRIGGER_* but the PIC does not support
                                 * multiple flow-types?
                                 */
                                printk(KERN_WARNING "No IRQF_TRIGGER set_type "
                                       "function for IRQ %d (%s)\n", irq,
                                       desc->chip ? desc->chip->name :
                                       "unknown");
                } else
                        compat_irq_chip_set_default_handler(desc);

                desc->status &= ~(IRQ_AUTODETECT | IRQ_WAITING |
                                  IRQ_INPROGRESS);

                if (!(desc->status & IRQ_NOAUTOEN)) {
                        desc->depth = 0;
                        desc->status &= ~IRQ_DISABLED;
                        if (desc->chip->startup)
                                desc->chip->startup(irq);
                        else
                                desc->chip->enable(irq);
                } else
                        /* Undo nested disables: */
                        desc->depth = 1;
        }
        /* Reset broken irq detection when installing new handler */
        desc->irq_count = 0;
        desc->irqs_unhandled = 0;
        spin_unlock_irqrestore(&desc->lock, flags);

        new->irq = irq;
        register_irq_proc(irq);
        new->dir = NULL;
        register_handler_proc(irq, new);

        return 0;

mismatch:
#ifdef CONFIG_DEBUG_SHIRQ
        if (!(new->flags & IRQF_PROBE_SHARED)) {
                printk(KERN_ERR "IRQ handler type mismatch for IRQ %d\n", irq);
                if (old_name)
                        printk(KERN_ERR "current handler: %s\n", old_name);
                dump_stack();
        }
#endif
        spin_unlock_irqrestore(&desc->lock, flags);
        return -EBUSY;
}

/**
 *      free_irq - free an interrupt
 *      @irq: Interrupt line to free
 *      @dev_id: Device identity to free
 *
 *      Remove an interrupt handler. The handler is removed and if the
 *      interrupt line is no longer in use by any driver it is disabled.
 *      On a shared IRQ the caller must ensure the interrupt is disabled
 *      on the card it drives before calling this function. The function
 *      does not return until any executing interrupts for this IRQ
 *      have completed.
 *
 *      This function must not be called from interrupt context.
 */
void free_irq(unsigned int irq, void *dev_id)
{
        struct irq_desc *desc;
        struct irqaction **p;
        unsigned long flags;

        WARN_ON(in_interrupt());
        if (irq >= NR_IRQS)
                return;

        desc = irq_desc + irq;
        spin_lock_irqsave(&desc->lock, flags);
        p = &desc->action;
        for (;;) {
                struct irqaction *action = *p;

                if (action) {
                        struct irqaction **pp = p;

                        p = &action->next;
                        if (action->dev_id != dev_id)
                                continue;

                        /* Found it - now remove it from the list of entries */
                        *pp = action->next;

                        /* Currently used only by UML, might disappear one day.*/
#ifdef CONFIG_IRQ_RELEASE_METHOD
                        if (desc->chip->release)
                                desc->chip->release(irq, dev_id);
#endif

                        if (!desc->action) {
                                desc->status |= IRQ_DISABLED;
                                if (desc->chip->shutdown)
                                        desc->chip->shutdown(irq);
                                else
                                        desc->chip->disable(irq);
                        }
                        spin_unlock_irqrestore(&desc->lock, flags);
                        unregister_handler_proc(irq, action);

                        /* Make sure it's not being used on another CPU */
                        synchronize_irq(irq);
#ifdef CONFIG_DEBUG_SHIRQ
                        /*
                         * It's a shared IRQ -- the driver ought to be
                         * prepared for it to happen even now it's
                         * being freed, so let's make sure....  We do
                         * this after actually deregistering it, to
                         * make sure that a 'real' IRQ doesn't run in
                         * parallel with our fake
                         */
                        if (action->flags & IRQF_SHARED) {
                                local_irq_save(flags);
                                action->handler(irq, dev_id);
                                local_irq_restore(flags);
                        }
#endif
                        kfree(action);
                        return;
                }
                printk(KERN_ERR "Trying to free already-free IRQ %d\n", irq);
#ifdef CONFIG_DEBUG_SHIRQ
                dump_stack();
#endif
                spin_unlock_irqrestore(&desc->lock, flags);
                return;
        }
}
EXPORT_SYMBOL(free_irq);

/**
 *      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:
 *
 *      IRQF_SHARED             Interrupt is shared
 *      IRQF_DISABLED   Disable local interrupts while processing
 *      IRQF_SAMPLE_RANDOM      The interrupt can be used for entropy
 *
 */
int request_irq(unsigned int irq, irq_handler_t handler,
                unsigned long irqflags, const char *devname, void *dev_id)
{
        struct irqaction *action;
        int retval;

#ifdef CONFIG_LOCKDEP
        /*
         * Lockdep wants atomic interrupt handlers:
         */
        irqflags |= IRQF_DISABLED;
#endif
        /*
         * Sanity-check: shared interrupts must 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 & IRQF_SHARED) && !dev_id)
                return -EINVAL;
        if (irq >= NR_IRQS)
                return -EINVAL;
        if (irq_desc[irq].status & IRQ_NOREQUEST)
                return -EINVAL;
        if (!handler)
                return -EINVAL;

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

        action->handler = handler;
        action->flags = irqflags;
        cpus_clear(action->mask);
        action->name = devname;
        action->next = NULL;
        action->dev_id = dev_id;

        select_smp_affinity(irq);

#ifdef CONFIG_DEBUG_SHIRQ
        if (irqflags & IRQF_SHARED) {
                /*
                 * It's a shared IRQ -- the driver ought to be prepared for it
                 * to happen immediately, so let's make sure....
                 * We do this before actually registering it, to make sure that
                 * a 'real' IRQ doesn't run in parallel with our fake
                 */
                unsigned long flags;

                local_irq_save(flags);
                handler(irq, dev_id);
                local_irq_restore(flags);
        }
#endif

        retval = setup_irq(irq, action);
        if (retval)
                kfree(action);

        return retval;
}
EXPORT_SYMBOL(request_irq);