Linux-2.6.12-rc2

[thirdparty/kernel/stable.git] / arch / alpha / kernel / irq.c

/*
 *      linux/arch/alpha/kernel/irq.c
 *
 *      Copyright (C) 1995 Linus Torvalds
 *
 * This file contains the code used by various IRQ handling routines:
 * asking for different IRQ's should be done through these routines
 * instead of just grabbing them. Thus setups with different IRQ numbers
 * shouldn't result in any weird surprises, and installing new handlers
 * should be easier.
 */

#include <linux/config.h>
#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/errno.h>
#include <linux/kernel_stat.h>
#include <linux/signal.h>
#include <linux/sched.h>
#include <linux/ptrace.h>
#include <linux/interrupt.h>
#include <linux/slab.h>
#include <linux/random.h>
#include <linux/init.h>
#include <linux/irq.h>
#include <linux/proc_fs.h>
#include <linux/seq_file.h>
#include <linux/profile.h>
#include <linux/bitops.h>

#include <asm/system.h>
#include <asm/io.h>
#include <asm/uaccess.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
        }
};

static void register_irq_proc(unsigned int irq);

volatile unsigned long irq_err_count;

/*
 * 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 no_irq_enable_disable(unsigned int irq) { }
static unsigned int no_irq_startup(unsigned int irq) { return 0; }

static void
no_irq_ack(unsigned int irq)
{
        irq_err_count++;
        printk(KERN_CRIT "Unexpected IRQ trap at vector %u\n", irq);
}

struct hw_interrupt_type no_irq_type = {
        .typename       = "none",
        .startup        = no_irq_startup,
        .shutdown       = no_irq_enable_disable,
        .enable         = no_irq_enable_disable,
        .disable        = no_irq_enable_disable,
        .ack            = no_irq_ack,
        .end            = no_irq_enable_disable,
};

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;

        do {
                if (!(action->flags & SA_INTERRUPT))
                        local_irq_enable();
                else
                        local_irq_disable();

                ret = action->handler(irq, action->dev_id, regs);
                if (ret == IRQ_HANDLED)
                        status |= action->flags;
                action = action->next;
        } while (action);
        if (status & SA_SAMPLE_RANDOM)
                add_interrupt_randomness(irq);
        local_irq_disable();

        return status;
}

/*
 * 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. 
 */
void inline
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)
{
        disable_irq_nosync(irq);
        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;
                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(KERN_ERR "enable_irq() unbalanced from %p\n",
                       __builtin_return_address(0));
        }
        spin_unlock_irqrestore(&desc->lock, flags);
}

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;
}

static struct proc_dir_entry * root_irq_dir;
static struct proc_dir_entry * irq_dir[NR_IRQS];

#ifdef CONFIG_SMP 
static struct proc_dir_entry * smp_affinity_entry[NR_IRQS];
static char irq_user_affinity[NR_IRQS];
static cpumask_t irq_affinity[NR_IRQS] = { [0 ... NR_IRQS-1] = CPU_MASK_ALL };

static void
select_smp_affinity(int irq)
{
        static int last_cpu;
        int cpu = last_cpu + 1;

        if (! irq_desc[irq].handler->set_affinity || irq_user_affinity[irq])
                return;

        while (!cpu_possible(cpu))
                cpu = (cpu < (NR_CPUS-1) ? cpu + 1 : 0);
        last_cpu = cpu;

        irq_affinity[irq] = cpumask_of_cpu(cpu);
        irq_desc[irq].handler->set_affinity(irq, cpumask_of_cpu(cpu));
}

static int
irq_affinity_read_proc (char *page, char **start, off_t off,
                        int count, int *eof, void *data)
{
        int len = cpumask_scnprintf(page, count, irq_affinity[(long)data]);
        if (count - len < 2)
                return -EINVAL;
        len += sprintf(page + len, "\n");
        return len;
}

static int
irq_affinity_write_proc(struct file *file, const char __user *buffer,
                        unsigned long count, void *data)
{
        int irq = (long) data, full_count = count, err;
        cpumask_t new_value;

        if (!irq_desc[irq].handler->set_affinity)
                return -EIO;

        err = cpumask_parse(buffer, count, new_value);

        /* The special value 0 means release control of the
           affinity to kernel.  */
        cpus_and(new_value, new_value, cpu_online_map);
        if (cpus_empty(new_value)) {
                irq_user_affinity[irq] = 0;
                select_smp_affinity(irq);
        }
        /* Do not allow disabling IRQs completely - it's a too easy
           way to make the system unusable accidentally :-) At least
           one online CPU still has to be targeted.  */
        else {
                irq_affinity[irq] = new_value;
                irq_user_affinity[irq] = 1;
                irq_desc[irq].handler->set_affinity(irq, new_value);
        }

        return full_count;
}

#endif /* CONFIG_SMP */

#define MAX_NAMELEN 10

static void
register_irq_proc (unsigned int irq)
{
        char name [MAX_NAMELEN];

        if (!root_irq_dir || (irq_desc[irq].handler == &no_irq_type) ||
            irq_dir[irq])
                return;

        memset(name, 0, MAX_NAMELEN);
        sprintf(name, "%d", irq);

        /* create /proc/irq/1234 */
        irq_dir[irq] = proc_mkdir(name, root_irq_dir);

#ifdef CONFIG_SMP 
        if (irq_desc[irq].handler->set_affinity) {
                struct proc_dir_entry *entry;
                /* create /proc/irq/1234/smp_affinity */
                entry = create_proc_entry("smp_affinity", 0600, irq_dir[irq]);

                if (entry) {
                        entry->nlink = 1;
                        entry->data = (void *)(long)irq;
                        entry->read_proc = irq_affinity_read_proc;
                        entry->write_proc = irq_affinity_write_proc;
                }

                smp_affinity_entry[irq] = entry;
        }
#endif
}

void
init_irq_proc (void)
{
        int i;

        /* create /proc/irq */
        root_irq_dir = proc_mkdir("irq", NULL);

#ifdef CONFIG_SMP 
        /* create /proc/irq/prof_cpu_mask */
        create_prof_cpu_mask(root_irq_dir);
#endif

        /*
         * Create entries for all existing IRQs.
         */
        for (i = 0; i < ACTUAL_NR_IRQS; i++) {
                if (irq_desc[i].handler == &no_irq_type)
                        continue;
                register_irq_proc(i);
        }
}

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;

#if 1
        /*
         * Sanity-check: shared interrupts should REALLY 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 & SA_SHIRQ) && !dev_id) {
                printk(KERN_ERR
                       "Bad boy: %s (at %p) called us without a dev_id!\n",
                       devname, __builtin_return_address(0));
        }
#endif

        action = (struct irqaction *)
                        kmalloc(sizeof(struct irqaction), GFP_KERNEL);
        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;

#ifdef CONFIG_SMP
        select_smp_affinity(irq);
#endif

        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) {
                printk(KERN_CRIT "Trying to free IRQ%d\n", irq);
                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 - 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);

#ifdef CONFIG_SMP
                        /* Wait to make sure it's not being used on
                           another CPU.  */
                        while (desc->status & IRQ_INPROGRESS)
                                barrier();
#endif
                        kfree(action);
                        return;
                }
                printk(KERN_ERR "Trying to free free IRQ%d\n",irq);
                spin_unlock_irqrestore(&desc->lock,flags);
                return;
        }
}

EXPORT_SYMBOL(free_irq);

int
show_interrupts(struct seq_file *p, void *v)
{
#ifdef CONFIG_SMP
        int j;
#endif
        int i = *(loff_t *) v;
        struct irqaction * action;
        unsigned long flags;

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

        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);
#ifndef CONFIG_SMP
                seq_printf(p, "%10u ", kstat_irqs(i));
#else
                for (j = 0; j < NR_CPUS; j++)
                        if (cpu_online(j))
                                seq_printf(p, "%10u ", kstat_cpu(j).irqs[i]);
#endif
                seq_printf(p, " %14s", irq_desc[i].handler->typename);
                seq_printf(p, "  %c%s",
                        (action->flags & SA_INTERRUPT)?'+':' ',
                        action->name);

                for (action=action->next; action; action = action->next) {
                        seq_printf(p, ", %c%s",
                                  (action->flags & SA_INTERRUPT)?'+':' ',
                                   action->name);
                }

                seq_putc(p, '\n');
unlock:
                spin_unlock_irqrestore(&irq_desc[i].lock, flags);
        } else if (i == ACTUAL_NR_IRQS) {
#ifdef CONFIG_SMP
                seq_puts(p, "IPI: ");
                for (i = 0; i < NR_CPUS; i++)
                        if (cpu_online(i))
                                seq_printf(p, "%10lu ", cpu_data[i].ipi_count);
                seq_putc(p, '\n');
#endif
                seq_printf(p, "ERR: %10lu\n", irq_err_count);
        }
        return 0;
}


/*
 * handle_irq handles all normal device IRQ's (the special
 * SMP cross-CPU interrupts have their own specific
 * handlers).
 */

#define MAX_ILLEGAL_IRQS 16

void
handle_irq(int irq, 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 cpu = smp_processor_id();
        irq_desc_t *desc = irq_desc + irq;
        struct irqaction * action;
        unsigned int status;
        static unsigned int illegal_count=0;
        
        if ((unsigned) irq > ACTUAL_NR_IRQS && illegal_count < MAX_ILLEGAL_IRQS ) {
                irq_err_count++;
                illegal_count++;
                printk(KERN_CRIT "device_interrupt: invalid interrupt %d\n",
                       irq);
                return;
        }

        irq_enter();
        kstat_cpu(cpu).irqs[irq]++;
        spin_lock_irq(&desc->lock); /* mask also the higher prio events */
        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 (!(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 (!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 handle_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 (;;) {
                spin_unlock(&desc->lock);
                handle_IRQ_event(irq, regs, action);
                spin_lock(&desc->lock);
                
                if (!(desc->status & IRQ_PENDING)
                    || (desc->status & IRQ_LEVEL))
                        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();
}

/*
 * 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)
{
        int i;
        irq_desc_t *desc;
        unsigned long delay;
        unsigned long val;

        /* 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 (!irq_desc[i].action) 
                        irq_desc[i].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) first, enable any unassigned irqs. */
        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++) {
                irq_desc_t *desc = irq_desc + i;
                unsigned int status;

                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).
 */
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) {
                        /* We only react to ISA interrupts */
                        if (!(status & IRQ_WAITING)) {
                                if (i < 16)
                                        mask |= 1 << i;
                        }

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

        return mask & val;
}

/*
 * Get the result of the IRQ probe.. A negative result means that
 * we have several candidates (but we return the lowest-numbered
 * one).
 */

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);
        }

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

EXPORT_SYMBOL(probe_irq_off);

#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