[PATCH] r/o bind mounts: unlink: monitor i_nlink

[linux-2.6/kvm.git] / kernel / irq / chip.c

/*
 * linux/kernel/irq/chip.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, for irq-chip
 * based architectures.
 *
 * Detailed information is available in Documentation/DocBook/genericirq
 */

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

#include "internals.h"

/**
 *      set_irq_chip - set the irq chip for an irq
 *      @irq:   irq number
 *      @chip:  pointer to irq chip description structure
 */
int set_irq_chip(unsigned int irq, struct irq_chip *chip)
{
        struct irq_desc *desc;
        unsigned long flags;

        if (irq >= NR_IRQS) {
                printk(KERN_ERR "Trying to install chip for IRQ%d\n", irq);
                WARN_ON(1);
                return -EINVAL;
        }

        if (!chip)
                chip = &no_irq_chip;

        desc = irq_desc + irq;
        spin_lock_irqsave(&desc->lock, flags);
        irq_chip_set_defaults(chip);
        desc->chip = chip;
        spin_unlock_irqrestore(&desc->lock, flags);

        return 0;
}
EXPORT_SYMBOL(set_irq_chip);

/**
 *      set_irq_type - set the irq type for an irq
 *      @irq:   irq number
 *      @type:  interrupt type - see include/linux/interrupt.h
 */
int set_irq_type(unsigned int irq, unsigned int type)
{
        struct irq_desc *desc;
        unsigned long flags;
        int ret = -ENXIO;

        if (irq >= NR_IRQS) {
                printk(KERN_ERR "Trying to set irq type for IRQ%d\n", irq);
                return -ENODEV;
        }

        desc = irq_desc + irq;
        if (desc->chip->set_type) {
                spin_lock_irqsave(&desc->lock, flags);
                ret = desc->chip->set_type(irq, type);
                spin_unlock_irqrestore(&desc->lock, flags);
        }
        return ret;
}
EXPORT_SYMBOL(set_irq_type);

/**
 *      set_irq_data - set irq type data for an irq
 *      @irq:   Interrupt number
 *      @data:  Pointer to interrupt specific data
 *
 *      Set the hardware irq controller data for an irq
 */
int set_irq_data(unsigned int irq, void *data)
{
        struct irq_desc *desc;
        unsigned long flags;

        if (irq >= NR_IRQS) {
                printk(KERN_ERR
                       "Trying to install controller data for IRQ%d\n", irq);
                return -EINVAL;
        }

        desc = irq_desc + irq;
        spin_lock_irqsave(&desc->lock, flags);
        desc->handler_data = data;
        spin_unlock_irqrestore(&desc->lock, flags);
        return 0;
}
EXPORT_SYMBOL(set_irq_data);

/**
 *      set_irq_chip_data - set irq chip data for an irq
 *      @irq:   Interrupt number
 *      @data:  Pointer to chip specific data
 *
 *      Set the hardware irq chip data for an irq
 */
int set_irq_chip_data(unsigned int irq, void *data)
{
        struct irq_desc *desc = irq_desc + irq;
        unsigned long flags;

        if (irq >= NR_IRQS || !desc->chip) {
                printk(KERN_ERR "BUG: bad set_irq_chip_data(IRQ#%d)\n", irq);
                return -EINVAL;
        }

        spin_lock_irqsave(&desc->lock, flags);
        desc->chip_data = data;
        spin_unlock_irqrestore(&desc->lock, flags);

        return 0;
}
EXPORT_SYMBOL(set_irq_chip_data);

/*
 * default enable function
 */
static void default_enable(unsigned int irq)
{
        struct irq_desc *desc = irq_desc + irq;

        desc->chip->unmask(irq);
        desc->status &= ~IRQ_MASKED;
}

/*
 * default disable function
 */
static void default_disable(unsigned int irq)
{
        struct irq_desc *desc = irq_desc + irq;

        if (!(desc->status & IRQ_DELAYED_DISABLE))
                desc->chip->mask(irq);
}

/*
 * default startup function
 */
static unsigned int default_startup(unsigned int irq)
{
        irq_desc[irq].chip->enable(irq);

        return 0;
}

/*
 * Fixup enable/disable function pointers
 */
void irq_chip_set_defaults(struct irq_chip *chip)
{
        if (!chip->enable)
                chip->enable = default_enable;
        if (!chip->disable)
                chip->disable = default_disable;
        if (!chip->startup)
                chip->startup = default_startup;
        if (!chip->shutdown)
                chip->shutdown = chip->disable;
        if (!chip->name)
                chip->name = chip->typename;
}

static inline void mask_ack_irq(struct irq_desc *desc, int irq)
{
        if (desc->chip->mask_ack)
                desc->chip->mask_ack(irq);
        else {
                desc->chip->mask(irq);
                desc->chip->ack(irq);
        }
}

/**
 *      handle_simple_irq - Simple and software-decoded IRQs.
 *      @irq:   the interrupt number
 *      @desc:  the interrupt description structure for this irq
 *      @regs:  pointer to a register structure
 *
 *      Simple interrupts are either sent from a demultiplexing interrupt
 *      handler or come from hardware, where no interrupt hardware control
 *      is necessary.
 *
 *      Note: The caller is expected to handle the ack, clear, mask and
 *      unmask issues if necessary.
 */
void fastcall
handle_simple_irq(unsigned int irq, struct irq_desc *desc, struct pt_regs *regs)
{
        struct irqaction *action;
        irqreturn_t action_ret;
        const unsigned int cpu = smp_processor_id();

        spin_lock(&desc->lock);

        if (unlikely(desc->status & IRQ_INPROGRESS))
                goto out_unlock;
        desc->status &= ~(IRQ_REPLAY | IRQ_WAITING);
        kstat_cpu(cpu).irqs[irq]++;

        action = desc->action;
        if (unlikely(!action || (desc->status & IRQ_DISABLED)))
                goto out_unlock;

        desc->status |= IRQ_INPROGRESS;
        spin_unlock(&desc->lock);

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

        spin_lock(&desc->lock);
        desc->status &= ~IRQ_INPROGRESS;
out_unlock:
        spin_unlock(&desc->lock);
}

/**
 *      handle_level_irq - Level type irq handler
 *      @irq:   the interrupt number
 *      @desc:  the interrupt description structure for this irq
 *      @regs:  pointer to a register structure
 *
 *      Level type interrupts are active as long as the hardware line has
 *      the active level. This may require to mask the interrupt and unmask
 *      it after the associated handler has acknowledged the device, so the
 *      interrupt line is back to inactive.
 */
void fastcall
handle_level_irq(unsigned int irq, struct irq_desc *desc, struct pt_regs *regs)
{
        unsigned int cpu = smp_processor_id();
        struct irqaction *action;
        irqreturn_t action_ret;

        spin_lock(&desc->lock);
        mask_ack_irq(desc, irq);

        if (unlikely(desc->status & IRQ_INPROGRESS))
                goto out_unlock;
        desc->status &= ~(IRQ_REPLAY | IRQ_WAITING);
        kstat_cpu(cpu).irqs[irq]++;

        /*
         * If its disabled or no action available
         * keep it masked and get out of here
         */
        action = desc->action;
        if (unlikely(!action || (desc->status & IRQ_DISABLED))) {
                desc->status |= IRQ_PENDING;
                goto out_unlock;
        }

        desc->status |= IRQ_INPROGRESS;
        desc->status &= ~IRQ_PENDING;
        spin_unlock(&desc->lock);

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

        spin_lock(&desc->lock);
        desc->status &= ~IRQ_INPROGRESS;
        if (!(desc->status & IRQ_DISABLED) && desc->chip->unmask)
                desc->chip->unmask(irq);
out_unlock:
        spin_unlock(&desc->lock);
}

/**
 *      handle_fasteoi_irq - irq handler for transparent controllers
 *      @irq:   the interrupt number
 *      @desc:  the interrupt description structure for this irq
 *      @regs:  pointer to a register structure
 *
 *      Only a single callback will be issued to the chip: an ->eoi()
 *      call when the interrupt has been serviced. This enables support
 *      for modern forms of interrupt handlers, which handle the flow
 *      details in hardware, transparently.
 */
void fastcall
handle_fasteoi_irq(unsigned int irq, struct irq_desc *desc,
                   struct pt_regs *regs)
{
        unsigned int cpu = smp_processor_id();
        struct irqaction *action;
        irqreturn_t action_ret;

        spin_lock(&desc->lock);

        if (unlikely(desc->status & IRQ_INPROGRESS))
                goto out;

        desc->status &= ~(IRQ_REPLAY | IRQ_WAITING);
        kstat_cpu(cpu).irqs[irq]++;

        /*
         * If its disabled or no action available
         * keep it masked and get out of here
         */
        action = desc->action;
        if (unlikely(!action || (desc->status & IRQ_DISABLED))) {
                desc->status |= IRQ_PENDING;
                goto out;
        }

        desc->status |= IRQ_INPROGRESS;
        desc->status &= ~IRQ_PENDING;
        spin_unlock(&desc->lock);

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

        spin_lock(&desc->lock);
        desc->status &= ~IRQ_INPROGRESS;
out:
        desc->chip->eoi(irq);

        spin_unlock(&desc->lock);
}

/**
 *      handle_edge_irq - edge type IRQ handler
 *      @irq:   the interrupt number
 *      @desc:  the interrupt description structure for this irq
 *      @regs:  pointer to a register structure
 *
 *      Interrupt occures on the falling and/or rising edge of a hardware
 *      signal. The occurence is latched into the irq controller hardware
 *      and must be acked in order to be reenabled. After the ack another
 *      interrupt can happen on the same source even before the first one
 *      is handled by the assosiacted event handler. If this happens it
 *      might be necessary to disable (mask) the interrupt depending on the
 *      controller hardware. This requires to reenable the interrupt inside
 *      of the loop which handles the interrupts which have arrived while
 *      the handler was running. If all pending interrupts are handled, the
 *      loop is left.
 */
void fastcall
handle_edge_irq(unsigned int irq, struct irq_desc *desc, struct pt_regs *regs)
{
        const unsigned int cpu = smp_processor_id();

        spin_lock(&desc->lock);

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

        /*
         * If we're currently running this IRQ, or its disabled,
         * we shouldn't process the IRQ. Mark it pending, handle
         * the necessary masking and go out
         */
        if (unlikely((desc->status & (IRQ_INPROGRESS | IRQ_DISABLED)) ||
                    !desc->action)) {
                desc->status |= (IRQ_PENDING | IRQ_MASKED);
                mask_ack_irq(desc, irq);
                goto out_unlock;
        }

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

        /* Start handling the irq */
        desc->chip->ack(irq);

        /* Mark the IRQ currently in progress.*/
        desc->status |= IRQ_INPROGRESS;

        do {
                struct irqaction *action = desc->action;
                irqreturn_t action_ret;

                if (unlikely(!action)) {
                        desc->chip->mask(irq);
                        goto out_unlock;
                }

                /*
                 * When another irq arrived while we were handling
                 * one, we could have masked the irq.
                 * Renable it, if it was not disabled in meantime.
                 */
                if (unlikely((desc->status &
                               (IRQ_PENDING | IRQ_MASKED | IRQ_DISABLED)) ==
                              (IRQ_PENDING | IRQ_MASKED))) {
                        desc->chip->unmask(irq);
                        desc->status &= ~IRQ_MASKED;
                }

                desc->status &= ~IRQ_PENDING;
                spin_unlock(&desc->lock);
                action_ret = handle_IRQ_event(irq, regs, action);
                if (!noirqdebug)
                        note_interrupt(irq, desc, action_ret, regs);
                spin_lock(&desc->lock);

        } while ((desc->status & (IRQ_PENDING | IRQ_DISABLED)) == IRQ_PENDING);

        desc->status &= ~IRQ_INPROGRESS;
out_unlock:
        spin_unlock(&desc->lock);
}

#ifdef CONFIG_SMP
/**
 *      handle_percpu_IRQ - Per CPU local irq handler
 *      @irq:   the interrupt number
 *      @desc:  the interrupt description structure for this irq
 *      @regs:  pointer to a register structure
 *
 *      Per CPU interrupts on SMP machines without locking requirements
 */
void fastcall
handle_percpu_irq(unsigned int irq, struct irq_desc *desc, struct pt_regs *regs)
{
        irqreturn_t action_ret;

        kstat_this_cpu.irqs[irq]++;

        if (desc->chip->ack)
                desc->chip->ack(irq);

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

        if (desc->chip->eoi)
                desc->chip->eoi(irq);
}

#endif /* CONFIG_SMP */

void
__set_irq_handler(unsigned int irq,
                  void fastcall (*handle)(unsigned int, irq_desc_t *,
                                          struct pt_regs *),
                  int is_chained)
{
        struct irq_desc *desc;
        unsigned long flags;

        if (irq >= NR_IRQS) {
                printk(KERN_ERR
                       "Trying to install type control for IRQ%d\n", irq);
                return;
        }

        desc = irq_desc + irq;

        if (!handle)
                handle = handle_bad_irq;

        if (desc->chip == &no_irq_chip) {
                printk(KERN_WARNING "Trying to install %sinterrupt handler "
                       "for IRQ%d\n", is_chained ? "chained " : " ", irq);
                /*
                 * Some ARM implementations install a handler for really dumb
                 * interrupt hardware without setting an irq_chip. This worked
                 * with the ARM no_irq_chip but the check in setup_irq would
                 * prevent us to setup the interrupt at all. Switch it to
                 * dummy_irq_chip for easy transition.
                 */
                desc->chip = &dummy_irq_chip;
        }

        spin_lock_irqsave(&desc->lock, flags);

        /* Uninstall? */
        if (handle == handle_bad_irq) {
                if (desc->chip != &no_irq_chip) {
                        desc->chip->mask(irq);
                        desc->chip->ack(irq);
                }
                desc->status |= IRQ_DISABLED;
                desc->depth = 1;
        }
        desc->handle_irq = handle;

        if (handle != handle_bad_irq && is_chained) {
                desc->status &= ~IRQ_DISABLED;
                desc->status |= IRQ_NOREQUEST | IRQ_NOPROBE;
                desc->depth = 0;
                desc->chip->unmask(irq);
        }
        spin_unlock_irqrestore(&desc->lock, flags);
}

void
set_irq_chip_and_handler(unsigned int irq, struct irq_chip *chip,
                         void fastcall (*handle)(unsigned int,
                                                 struct irq_desc *,
                                                 struct pt_regs *))
{
        set_irq_chip(irq, chip);
        __set_irq_handler(irq, handle, 0);
}

/*
 * Get a descriptive string for the highlevel handler, for
 * /proc/interrupts output:
 */
const char *
handle_irq_name(void fastcall (*handle)(unsigned int, struct irq_desc *,
                                        struct pt_regs *))
{
        if (handle == handle_level_irq)
                return "level  ";
        if (handle == handle_fasteoi_irq)
                return "fasteoi";
        if (handle == handle_edge_irq)
                return "edge   ";
        if (handle == handle_simple_irq)
                return "simple ";
#ifdef CONFIG_SMP
        if (handle == handle_percpu_irq)
                return "percpu ";
#endif
        if (handle == handle_bad_irq)
                return "bad    ";

        return NULL;
}