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[linux-2.6.9-moxart.git] / arch / sh / kernel / irq.c

/* $Id: irq.c,v 1.20 2004/01/13 05:52:11 kkojima Exp $
 *
 * linux/arch/sh/kernel/irq.c
 *
 *      Copyright (C) 1992, 1998 Linus Torvalds, Ingo Molnar
 *
 *
 * SuperH version:  Copyright (C) 1999  Niibe Yutaka
 */

/*
 * IRQs are in fact implemented a bit like signal handlers for the kernel.
 * Naturally it's not a 1:1 relation, but there are similarities.
 */

#include <linux/config.h>
#include <linux/module.h>
#include <linux/ptrace.h>
#include <linux/errno.h>
#include <linux/kernel_stat.h>
#include <linux/signal.h>
#include <linux/sched.h>
#include <linux/ioport.h>
#include <linux/interrupt.h>
#include <linux/timex.h>
#include <linux/mm.h>
#include <linux/slab.h>
#include <linux/random.h>
#include <linux/smp.h>
#include <linux/smp_lock.h>
#include <linux/init.h>
#include <linux/seq_file.h>
#include <linux/kallsyms.h>

#include <asm/system.h>
#include <asm/io.h>
#include <asm/bitops.h>
#include <asm/pgalloc.h>
#include <asm/delay.h>
#include <asm/irq.h>
#include <linux/irq.h>

/*
 * Controller mappings for all interrupt sources:
 */
irq_desc_t irq_desc[NR_IRQS] __cacheline_aligned = {
        [0 ... NR_IRQS-1] = {
                .handler = &no_irq_type,
                .lock = SPIN_LOCK_UNLOCKED
        }
};

/*
 * Special irq handlers.
 */

irqreturn_t no_action(int cpl, void *dev_id, struct pt_regs *regs)
{ return IRQ_NONE; }

/*
 * Generic no controller code
 */

static void enable_none(unsigned int irq) { }
static unsigned int startup_none(unsigned int irq) { return 0; }
static void disable_none(unsigned int irq) { }
static void ack_none(unsigned int irq)
{
/*
 * 'what should we do if we get a hw irq event on an illegal vector'.
 * each architecture has to answer this themselves, it doesn't deserve
 * a generic callback i think.
 */
        printk("unexpected IRQ trap at vector %02x\n", irq);
}

/* startup is the same as "enable", shutdown is same as "disable" */
#define shutdown_none   disable_none
#define end_none        enable_none

struct hw_interrupt_type no_irq_type = {
        "none",
        startup_none,
        shutdown_none,
        enable_none,
        disable_none,
        ack_none,
        end_none
};

/*
 * Generic, controller-independent functions:
 */

#if defined(CONFIG_PROC_FS)
int show_interrupts(struct seq_file *p, void *v)
{
        int i = *(loff_t *) v, j;
        struct irqaction * action;
        unsigned long flags;

        if (i == 0) {
                seq_puts(p, "           ");
                for (j=0; j<NR_CPUS; j++)
                        if (cpu_online(j))
                                seq_printf(p, "CPU%d       ",j);
                seq_putc(p, '\n');
        }

        if (i < ACTUAL_NR_IRQS) {
                spin_lock_irqsave(&irq_desc[i].lock, flags);
                action = irq_desc[i].action;
                if (!action)
                        goto unlock;
                seq_printf(p, "%3d: ",i);
                seq_printf(p, "%10u ", kstat_irqs(i));
                seq_printf(p, " %14s", irq_desc[i].handler->typename);
                seq_printf(p, "  %s", action->name);

                for (action=action->next; action; action = action->next)
                        seq_printf(p, ", %s", action->name);
                seq_putc(p, '\n');
unlock:
                spin_unlock_irqrestore(&irq_desc[i].lock, flags);
        }
        return 0;
}
#endif

/*
 * This should really return information about whether
 * we should do bottom half handling etc. Right now we
 * end up _always_ checking the bottom half, which is a
 * waste of time and is not what some drivers would
 * prefer.
 */
int handle_IRQ_event(unsigned int irq, struct pt_regs * regs, struct irqaction * action)
{
        int status = 1; /* Force the "do bottom halves" bit */
        int ret, retval = 0;

        if (!(action->flags & SA_INTERRUPT))
                local_irq_enable();

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

        if (status & SA_SAMPLE_RANDOM)
                add_interrupt_randomness(irq);

        local_irq_disable();
        return retval;
}

static void __report_bad_irq(int irq, irq_desc_t *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!\n", irq);
        }
        dump_stack();
        printk(KERN_ERR "handlers:\n");
        action = desc->action;
        do {
                printk(KERN_ERR "[<%p>]", action->handler);
                print_symbol(" (%s)",
                        (unsigned long)action->handler);
                printk("\n");
                action = action->next;
        } while (action);
}

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

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

static int noirqdebug;

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

__setup("noirqdebug", noirqdebug_setup);

/*
 * 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 note_interrupt(int irq, irq_desc_t *desc, irqreturn_t action_ret)
{
        if (action_ret != IRQ_HANDLED) {
                desc->irqs_unhandled++;
                if (action_ret != IRQ_NONE)
                        report_bad_irq(irq, desc, action_ret);
        }

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

        desc->irq_count = 0;
        if (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;
                desc->handler->disable(irq);
        }
        desc->irqs_unhandled = 0;
}

/*
 * Generic enable/disable code: this just calls
 * down into the PIC-specific version for the actual
 * hardware disable after having gotten the irq
 * controller lock. 
 */
inline void disable_irq_nosync(unsigned int irq)
{
        irq_desc_t *desc = irq_desc + irq;
        unsigned long flags;

        spin_lock_irqsave(&desc->lock, flags);
        if (!desc->depth++) {
                desc->status |= IRQ_DISABLED;
                desc->handler->disable(irq);
        }
        spin_unlock_irqrestore(&desc->lock, flags);
}

/*
 * Synchronous version of the above, making sure the IRQ is
 * no longer running on any other IRQ..
 */
void disable_irq(unsigned int irq)
{
        irq_desc_t *desc = irq_desc + irq;
        disable_irq_nosync(irq);
        if (desc->action)
                synchronize_irq(irq);
}

void enable_irq(unsigned int irq)
{
        irq_desc_t *desc = irq_desc + irq;
        unsigned long flags;

        spin_lock_irqsave(&desc->lock, flags);
        switch (desc->depth) {
        case 1: {
                unsigned int status = desc->status & ~(IRQ_DISABLED | IRQ_INPROGRESS);
                desc->status = status;
                if ((status & (IRQ_PENDING | IRQ_REPLAY)) == IRQ_PENDING) {
                        desc->status = status | IRQ_REPLAY;
                        hw_resend_irq(desc->handler,irq);
                }
                desc->handler->enable(irq);
                /* fall-through */
        }
        default:
                desc->depth--;
                break;
        case 0:
                printk("enable_irq() unbalanced from %p\n",
                       __builtin_return_address(0));
        }
        spin_unlock_irqrestore(&desc->lock, flags);
}

/*
 * do_IRQ handles all normal device IRQ's.
 */
asmlinkage int do_IRQ(unsigned long r4, unsigned long r5,
                      unsigned long r6, unsigned long r7,
                      struct pt_regs regs)
{       
        /* 
         * We ack quickly, we don't want the irq controller
         * thinking we're snobs just because some other CPU has
         * disabled global interrupts (we have already done the
         * INT_ACK cycles, it's too late to try to pretend to the
         * controller that we aren't taking the interrupt).
         *
         * 0 return value means that this irq is already being
         * handled by some other CPU. (or is disabled)
         */
        int irq;
        irq_desc_t *desc;
        struct irqaction * action;
        unsigned int status;

        irq_enter();

#ifdef CONFIG_PREEMPT
        /*
         * At this point we're now about to actually call handlers,
         * and interrupts might get reenabled during them... bump
         * preempt_count to prevent any preemption while the handler
         * called here is pending...
         */
        preempt_disable();
#endif

        /* Get IRQ number */
        asm volatile("stc       r2_bank, %0\n\t"
                     "shlr2     %0\n\t"
                     "shlr2     %0\n\t"
                     "shlr      %0\n\t"
                     "add       #-16, %0\n\t"
                     :"=z" (irq));
        irq = irq_demux(irq);

        kstat_this_cpu.irqs[irq]++;
        desc = irq_desc + irq;
        spin_lock(&desc->lock);
        desc->handler->ack(irq);
        /*
           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, &regs, action);
                spin_lock(&desc->lock);
                if (!noirqdebug)
                        note_interrupt(irq, desc, action_ret);
                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->handler->end(irq);
        spin_unlock(&desc->lock);

        irq_exit();

#ifdef CONFIG_PREEMPT
        /*
         * We're done with the handlers, interrupts should be
         * currently disabled; decrement preempt_count now so
         * as we return preemption may be allowed...
         */
        preempt_enable_no_resched();
#endif

        return 1;
}

int request_irq(unsigned int irq, 
                irqreturn_t (*handler)(int, void *, struct pt_regs *),
                unsigned long irqflags, 
                const char * devname,
                void *dev_id)
{
        int retval;
        struct irqaction * action;

        if (irq >= ACTUAL_NR_IRQS)
                return -EINVAL;
        if (!handler)
                return -EINVAL;

        action = (struct irqaction *)
                        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;

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

EXPORT_SYMBOL(request_irq);

void free_irq(unsigned int irq, void *dev_id)
{
        irq_desc_t *desc;
        struct irqaction **p;
        unsigned long flags;

        if (irq >= ACTUAL_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;
                        if (!desc->action) {
                                desc->status |= IRQ_DISABLED;
                                desc->handler->shutdown(irq);
                        }
                        spin_unlock_irqrestore(&desc->lock,flags);
                        synchronize_irq(irq);
                        kfree(action);
                        return;
                }
                printk("Trying to free free IRQ%d\n",irq);
                spin_unlock_irqrestore(&desc->lock,flags);
                return;
        }
}

EXPORT_SYMBOL(free_irq);

static DECLARE_MUTEX(probe_sem);

/*
 * IRQ autodetection code..
 *
 * This depends on the fact that any interrupt that
 * comes in on to an unassigned handler will get stuck
 * with "IRQ_WAITING" cleared and the interrupt
 * disabled.
 */
unsigned long probe_irq_on(void)
{
        unsigned int i;
        irq_desc_t *desc;
        unsigned long val;
        unsigned long delay;

        down(&probe_sem);
        /* 
         * something may have generated an irq long ago and we want to
         * flush such a longstanding irq before considering it as spurious. 
         */
        for (i = NR_IRQS-1; i > 0; i--) {
                desc = irq_desc + i;

                spin_lock_irq(&desc->lock);
                if (!desc->action)
                        desc->handler->startup(i);
                spin_unlock_irq(&desc->lock);
        }

        /* Wait for longstanding interrupts to trigger. */
        for (delay = jiffies + HZ/50; time_after(delay, jiffies); )
                /* about 20ms delay */ barrier();

        /*
         * enable any unassigned irqs
         * (we must startup again here because if a longstanding irq
         * happened in the previous stage, it may have masked itself)
         */
        for (i = NR_IRQS-1; i > 0; i--) {
                desc = irq_desc + i;

                spin_lock_irq(&desc->lock);
                if (!desc->action) {
                        desc->status |= IRQ_AUTODETECT | IRQ_WAITING;
                        if (desc->handler->startup(i))
                                desc->status |= IRQ_PENDING;
                }
                spin_unlock_irq(&desc->lock);
        }

        /*
         * Wait for spurious interrupts to trigger
         */
        for (delay = jiffies + HZ/10; time_after(delay, jiffies); )
                /* about 100ms delay */ barrier();

        /*
         * Now filter out any obviously spurious interrupts
         */
        val = 0;
        for (i=0; i<NR_IRQS; i++) {
                unsigned int status;

                desc = irq_desc + i;

                spin_lock_irq(&desc->lock);
                status = desc->status;

                if (status & IRQ_AUTODETECT) {
                        /* It triggered already - consider it spurious. */
                        if (!(status & IRQ_WAITING)) {
                                desc->status = status & ~IRQ_AUTODETECT;
                                desc->handler->shutdown(i);
                        } else
                                if (i < 32)
                                        val |= 1 << i;
                }
                spin_unlock_irq(&desc->lock);
        }

        return val;
}

EXPORT_SYMBOL(probe_irq_on);

/* Return a mask of triggered interrupts (this
 * can handle only legacy ISA interrupts).
 */

/*
 *      probe_irq_mask - scan a bitmap of interrupt lines
 *      @val:   mask of interrupts to consider
 *
 *      Scan the ISA bus interrupt lines and return a bitmap of
 *      active interrupts. The interrupt probe logic state is then
 *      returned to its previous value.
 *
 *      Note: we need to scan all the irq's even though we will
 *      only return ISA irq numbers - just so that we reset them
 *      all to a known state.
 */
unsigned int probe_irq_mask(unsigned long val)
{
        int i;
        unsigned int mask;

        mask = 0;
        for (i = 0; i < NR_IRQS; i++) {
                irq_desc_t *desc = irq_desc + i;
                unsigned int status;

                spin_lock_irq(&desc->lock);
                status = desc->status;

                if (status & IRQ_AUTODETECT) {
                        if (i < 16 && !(status & IRQ_WAITING))
                                mask |= 1 << i;

                        desc->status = status & ~IRQ_AUTODETECT;
                        desc->handler->shutdown(i);
                }
                spin_unlock_irq(&desc->lock);
        }
        up(&probe_sem);

        return mask & val;
}

int probe_irq_off(unsigned long val)
{
        int i, irq_found, nr_irqs;

        nr_irqs = 0;
        irq_found = 0;
        for (i=0; i<NR_IRQS; i++) {
                irq_desc_t *desc = irq_desc + i;
                unsigned int status;

                spin_lock_irq(&desc->lock);
                status = desc->status;

                if (status & IRQ_AUTODETECT) {
                        if (!(status & IRQ_WAITING)) {
                                if (!nr_irqs)
                                        irq_found = i;
                                nr_irqs++;
                        }
                        desc->status = status & ~IRQ_AUTODETECT;
                        desc->handler->shutdown(i);
                }
                spin_unlock_irq(&desc->lock);
        }
        up(&probe_sem);

        if (nr_irqs > 1)
                irq_found = -irq_found;
        return irq_found;
}

EXPORT_SYMBOL(probe_irq_off);

int setup_irq(unsigned int irq, struct irqaction * new)
{
        int shared = 0;
        struct irqaction *old, **p;
        unsigned long flags;
        irq_desc_t *desc = irq_desc + irq;

        if (desc->handler == &no_irq_type)
                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 & SA_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;
        if ((old = *p) != NULL) {
                /* Can't share interrupts unless both agree to */
                if (!(old->flags & new->flags & SA_SHIRQ)) {
                        spin_unlock_irqrestore(&desc->lock,flags);
                        return -EBUSY;
                }

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

        *p = new;

        if (!shared) {
                desc->depth = 0;
                desc->status &= ~(IRQ_DISABLED | IRQ_AUTODETECT | IRQ_WAITING | IRQ_INPROGRESS);
                desc->handler->startup(irq);
        }
        spin_unlock_irqrestore(&desc->lock,flags);
        return 0;
}

#if defined(CONFIG_PROC_FS) && defined(CONFIG_SYSCTL)

void init_irq_proc(void)
{
}
#endif

/* Taken from the 2.5 alpha port */
#ifdef CONFIG_SMP
void synchronize_irq(unsigned int irq)
{
        /* is there anything to synchronize with? */
        if (!irq_desc[irq].action)
                return;

        while (irq_desc[irq].status & IRQ_INPROGRESS)
                barrier();
}
#endif