[TG3]: Set minimal hw interrupt mitigation.

[linux-2.6/verdex.git] / arch / v850 / kernel / irq.c

/*
 * arch/v850/kernel/irq.c -- High-level interrupt handling
 *
 *  Copyright (C) 2001,02,03,04  NEC Electronics Corporation
 *  Copyright (C) 2001,02,03,04  Miles Bader <miles@gnu.org>
 *  Copyright (C) 1994-2000  Ralf Baechle
 *  Copyright (C) 1992  Linus Torvalds
 *
 * This file is subject to the terms and conditions of the GNU General
 * Public License.  See the file COPYING in the main directory of this
 * archive for more details.
 *
 * This file was was derived from the mips version, arch/mips/kernel/irq.c
 */

#include <linux/kernel.h>
#include <linux/module.h>
#include <linux/irq.h>
#include <linux/init.h>
#include <linux/interrupt.h>
#include <linux/kernel_stat.h>
#include <linux/slab.h>
#include <linux/mm.h>
#include <linux/random.h>
#include <linux/seq_file.h>

#include <asm/system.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("received IRQ %d with unknown interrupt type\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
};

volatile unsigned long irq_err_count, spurious_count;

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

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

        if (i == 0) {
                seq_puts(p, "           ");
                for (i=0; i < 1 /*smp_num_cpus*/; i++)
                        seq_printf(p, "CPU%d       ", i);
                seq_putc(p, '\n');
        }

        if (i < NR_IRQS) {
                int j, count, num;
                const char *type_name = irq_desc[i].handler->typename;
                spin_lock_irqsave(&irq_desc[j].lock, flags);
                action = irq_desc[i].action;
                if (!action) 
                        goto skip;

                count = 0;
                num = -1;
                for (j = 0; j < NR_IRQS; j++)
                        if (irq_desc[j].handler->typename == type_name) {
                                if (i == j)
                                        num = count;
                                count++;
                        }

                seq_printf(p, "%3d: ",i);
                seq_printf(p, "%10u ", kstat_irqs(i));
                if (count > 1) {
                        int prec = (num >= 100 ? 3 : num >= 10 ? 2 : 1);
                        seq_printf(p, " %*s%d", 14 - prec, type_name, num);
                } else
                        seq_printf(p, " %14s", type_name);
                
                seq_printf(p, "  %s", action->name);
                for (action=action->next; action; action = action->next)
                        seq_printf(p, ", %s", action->name);
                seq_putc(p, '\n');
skip:
                spin_unlock_irqrestore(&irq_desc[j].lock, flags);
        } else if (i == NR_IRQS)
                seq_printf(p, "ERR: %10lu\n", irq_err_count);
        return 0;
}

/*
 * 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;

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

        do {
                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. 
 */
 
/**
 *      disable_irq_nosync - disable an irq without waiting
 *      @irq: Interrupt to disable
 *
 *      Disable the selected interrupt line. Disables of an interrupt
 *      stack. 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 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);
}

/**
 *      disable_irq - disable an irq and wait for completion
 *      @irq: Interrupt to disable
 *
 *      Disable the selected interrupt line. Disables of an interrupt
 *      stack. That is for two disables you need two enables. 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)
{
        disable_irq_nosync(irq);
        synchronize_irq(irq);
}

/**
 *      enable_irq - enable interrupt handling on an irq
 *      @irq: Interrupt to enable
 *
 *      Re-enables the processing of interrupts on this IRQ line
 *      providing no disable_irq calls are now in effect.
 *
 *      This function may be called from IRQ context.
 */
 
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("enable_irq(%u) unbalanced from %p\n", irq,
                       __builtin_return_address(0));
        }
        spin_unlock_irqrestore(&desc->lock, flags);
}

/* Handle interrupt IRQ.  REGS are the registers at the time of ther
   interrupt.  */
unsigned int 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;

        irq_enter();
        kstat_cpu(cpu).irqs[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 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 (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();

        return 1;
}

/**
 *      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:
 *
 *      SA_SHIRQ                Interrupt is shared
 *
 *      SA_INTERRUPT            Disable local interrupts while processing
 *
 *      SA_SAMPLE_RANDOM        The interrupt can be used for entropy
 *
 */
 
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 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) {
                if (!dev_id)
                        printk("Bad boy: %s (at 0x%x) called us without a dev_id!\n", devname, (&irq)[-1]);
        }
#endif

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

        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;

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

EXPORT_SYMBOL(request_irq);

/**
 *      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 may be called from interrupt context. 
 *
 *      Bugs: Attempting to free an irq in a handler for the same irq hangs
 *            the machine.
 */
 
void free_irq(unsigned int irq, void *dev_id)
{
        irq_desc_t *desc;
        struct irqaction **p;
        unsigned long flags;

        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;
                        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);

/*
 * 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.
 */

static DECLARE_MUTEX(probe_sem);

/**
 *      probe_irq_on    - begin an interrupt autodetect
 *
 *      Commence probing for an interrupt. The interrupts are scanned
 *      and a mask of potential interrupt lines is returned.
 *
 */
 
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 (!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)
         */
        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).
 */
 
/**
 *      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;
}

/*
 * Return the one interrupt that triggered (this can
 * handle any interrupt source).
 */

/**
 *      probe_irq_off   - end an interrupt autodetect
 *      @val: mask of potential interrupts (unused)
 *
 *      Scans the unused interrupt lines and returns the line which
 *      appears to have triggered the interrupt. If no interrupt was
 *      found then zero is returned. If more than one interrupt is
 *      found then minus the first candidate is returned to indicate
 *      their is doubt.
 *
 *      The interrupt probe logic state is returned to its previous
 *      value.
 *
 *      BUGS: When used in a module (which arguably shouldnt happen)
 *      nothing prevents two IRQ probe callers from overlapping. The
 *      results of this are non-optimal.
 */
 
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);

/* this was setup_x86_irq but it seems pretty generic */
int setup_irq(unsigned int irq, struct irqaction * new)
{
        int shared = 0;
        unsigned long flags;
        struct irqaction *old, **p;
        irq_desc_t *desc = irq_desc + irq;

        /*
         * 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);

        /* register_irq_proc(irq); */
        return 0;
}

/* Initialize irq handling for IRQs.
   BASE_IRQ, BASE_IRQ+INTERVAL, ..., BASE_IRQ+NUM*INTERVAL
   to IRQ_TYPE.  An IRQ_TYPE of 0 means to use a generic interrupt type.  */
void __init
init_irq_handlers (int base_irq, int num, int interval,
                   struct hw_interrupt_type *irq_type)
{
        while (num-- > 0) {
                irq_desc[base_irq].status  = IRQ_DISABLED;
                irq_desc[base_irq].action  = NULL;
                irq_desc[base_irq].depth   = 1;
                irq_desc[base_irq].handler = irq_type;
                base_irq += interval;
        }
}

#if defined(CONFIG_PROC_FS) && defined(CONFIG_SYSCTL)
void init_irq_proc(void)
{
}
#endif /* CONFIG_PROC_FS && CONFIG_SYSCTL */