* better

[mascara-docs.git] / i386 / linux-2.3.21 / arch / arm / kernel / irq.c

/*
 *  linux/arch/arm/kernel/irq.c
 *
 *  Copyright (C) 1992 Linus Torvalds
 *  Modifications for ARM processor Copyright (C) 1995-1998 Russell King.
 *
 * 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.
 */

/*
 * IRQ's 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> /* for CONFIG_DEBUG_ERRORS */
#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/malloc.h>
#include <linux/random.h>
#include <linux/smp.h>
#include <linux/smp_lock.h>
#include <linux/init.h>

#include <asm/hardware.h>
#include <asm/io.h>
#include <asm/system.h>

#ifndef SMP
#define irq_enter(cpu, irq)     (++local_irq_count[cpu])
#define irq_exit(cpu, irq)      (--local_irq_count[cpu])
#else
#error SMP not supported
#endif

#ifndef cliIF
#define cliIF()
#endif

/*
 * Maximum IRQ count.  Currently, this is arbitary.
 * However, it should not be set too low to prevent
 * false triggering.  Conversely, if it is set too
 * high, then you could miss a stuck IRQ.
 *
 * Maybe we ought to set a timer and re-enable the
 * IRQ at a later time?
 */
#define MAX_IRQ_CNT     100000

unsigned int local_bh_count[NR_CPUS];
unsigned int local_irq_count[NR_CPUS];
spinlock_t irq_controller_lock;

int setup_arm_irq(int, struct irqaction *);
extern int get_fiq_list(char *);
extern void init_FIQ(void);

struct irqdesc {
        unsigned int     nomask   : 1;          /* IRQ does not mask in IRQ   */
        unsigned int     enabled  : 1;          /* IRQ is currently enabled   */
        unsigned int     triggered: 1;          /* IRQ has occurred           */
        unsigned int     probing  : 1;          /* IRQ in use for a probe     */
        unsigned int     probe_ok : 1;          /* IRQ can be used for probe  */
        unsigned int     valid    : 1;          /* IRQ claimable              */
        unsigned int     noautoenable : 1;      /* don't automatically enable IRQ */
        unsigned int     unused   :25;
        void (*mask_ack)(unsigned int irq);     /* Mask and acknowledge IRQ   */
        void (*mask)(unsigned int irq);         /* Mask IRQ                   */
        void (*unmask)(unsigned int irq);       /* Unmask IRQ                 */
        struct irqaction *action;
        /*
         * IRQ lock detection
         */
        unsigned int     lck_cnt;
        unsigned int     lck_pc;
        unsigned int     lck_jif;
};

static struct irqdesc irq_desc[NR_IRQS];

/*
 * Get architecture specific interrupt handlers
 * and interrupt initialisation.
 */
#include <asm/arch/irq.h>

/*
 * Dummy mask/unmask handler
 */
static void dummy_mask_unmask_irq(unsigned int irq)
{
}

void disable_irq(unsigned int irq)
{
        unsigned long flags;

        spin_lock_irqsave(&irq_controller_lock, flags);
        cliIF();
        irq_desc[irq].enabled = 0;
        irq_desc[irq].mask(irq);
        spin_unlock_irqrestore(&irq_controller_lock, flags);
}

void enable_irq(unsigned int irq)
{
        unsigned long flags;

        spin_lock_irqsave(&irq_controller_lock, flags);
        cliIF();
        irq_desc[irq].probing = 0;
        irq_desc[irq].triggered = 0;
        if (!irq_desc[irq].noautoenable) {
                irq_desc[irq].enabled = 1;
                irq_desc[irq].unmask(irq);
        }
        spin_unlock_irqrestore(&irq_controller_lock, flags);
}

int get_irq_list(char *buf)
{
        int i;
        struct irqaction * action;
        char *p = buf;

        for (i = 0 ; i < NR_IRQS ; i++) {
                action = irq_desc[i].action;
                if (!action)
                        continue;
                p += sprintf(p, "%3d: %10u   %s",
                             i, kstat_irqs(i), action->name);
                for (action = action->next; action; action = action->next) {
                        p += sprintf(p, ", %s", action->name);
                }
                *p++ = '\n';
        }

#ifdef CONFIG_ARCH_ACORN
        p += get_fiq_list(p);
#endif
        return p - buf;
}

/*
 * IRQ lock detection.
 *
 * Hopefully, this should get us out of a few locked situations.
 * However, it may take a while for this to happen, since we need
 * a large number if IRQs to appear in the same jiffie with the
 * same instruction pointer (or within 2 instructions).
 */
static void check_irq_lock(struct irqdesc *desc, int irq, struct pt_regs *regs)
{
        unsigned long instr_ptr = instruction_pointer(regs);

        if (desc->lck_jif == jiffies &&
            desc->lck_pc >= instr_ptr && desc->lck_pc < instr_ptr + 8) {
                desc->lck_cnt += 1;

                if (desc->lck_cnt > MAX_IRQ_CNT) {
                        printk(KERN_ERR "IRQ LOCK: IRQ%d is locking the system, disabled\n", irq);
                        disable_irq(irq);
                }
        } else {
                desc->lck_cnt = 0;
                desc->lck_pc  = instruction_pointer(regs);
                desc->lck_jif = jiffies;
        }
}

/*
 * do_IRQ handles all normal device IRQ's
 */
asmlinkage void do_IRQ(int irq, struct pt_regs * regs)
{
        struct irqdesc * desc;
        struct irqaction * action;
        int status, cpu;

        irq = fixup_irq(irq);

        desc = irq_desc + irq;

        spin_lock(&irq_controller_lock);
        desc->mask_ack(irq);
        spin_unlock(&irq_controller_lock);

        cpu = smp_processor_id();
        irq_enter(cpu, irq);
        kstat.irqs[cpu][irq]++;
        desc->triggered = 1;

        /* Return with this interrupt masked if no action */
        status = 0;
        action = desc->action;

        if (action) {
                if (desc->nomask) {
                        spin_lock(&irq_controller_lock);
                        desc->unmask(irq);
                        spin_unlock(&irq_controller_lock);
                }

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

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

                if (status & SA_SAMPLE_RANDOM)
                        add_interrupt_randomness(irq);
                __cli();

                if (!desc->nomask && desc->enabled) {
                        spin_lock(&irq_controller_lock);
                        desc->unmask(irq);
                        spin_unlock(&irq_controller_lock);
                }
        }

        /*
         * Debug measure - hopefully we can continue if an
         * IRQ lockup problem occurs...
         */
        check_irq_lock(desc, irq, regs);

        irq_exit(cpu, irq);

        /*
         * This should be conditional: we should really get
         * a return code from the irq handler to tell us
         * whether the handler wants us to do software bottom
         * half handling or not..
         */
        if (1) {
                if (bh_active & bh_mask)
                        do_bottom_half();
        }
}

#if defined(CONFIG_ARCH_ACORN)
void do_ecard_IRQ(int irq, struct pt_regs *regs)
{
        struct irqdesc * desc;
        struct irqaction * action;
        int cpu;

        desc = irq_desc + irq;

        cpu = smp_processor_id();
        kstat.irqs[cpu][irq]++;
        desc->triggered = 1;

        action = desc->action;

        if (action) {
                do {
                        action->handler(irq, action->dev_id, regs);
                        action = action->next;
                } while (action);
        } else {
                spin_lock(&irq_controller_lock);
                desc->mask(irq);
                spin_unlock(&irq_controller_lock);
        }
}
#endif

int setup_arm_irq(int irq, struct irqaction * new)
{
        int shared = 0;
        struct irqaction *old, **p;
        unsigned long flags;

        /*
         * 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(&irq_controller_lock, flags);
        p = &irq_desc[irq].action;
        if ((old = *p) != NULL) {
                /* Can't share interrupts unless both agree to */
                if (!(old->flags & new->flags & SA_SHIRQ)) {
                        spin_unlock_irqrestore(&irq_controller_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) {
                irq_desc[irq].nomask = (new->flags & SA_IRQNOMASK) ? 1 : 0;
                irq_desc[irq].probing = 0;
                if (!irq_desc[irq].noautoenable) {
                        irq_desc[irq].enabled = 1;
                        irq_desc[irq].unmask(irq);
                }
        }

        spin_unlock_irqrestore(&irq_controller_lock, flags);
        return 0;
}

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

        if (irq >= NR_IRQS || !irq_desc[irq].valid || !handler)
                return -EINVAL;

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

        action->handler = handler;
        action->flags = irq_flags;
        action->mask = 0;
        action->name = devname;
        action->next = NULL;
        action->dev_id = dev_id;

        retval = setup_arm_irq(irq, action);

        if (retval)
                kfree(action);
        return retval;
}

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

        if (irq >= NR_IRQS || !irq_desc[irq].valid) {
                printk(KERN_ERR "Trying to free IRQ%d\n",irq);
#ifdef CONFIG_DEBUG_ERRORS
                __backtrace();
#endif
                return;
        }

        spin_lock_irqsave(&irq_controller_lock, flags);
        for (p = &irq_desc[irq].action; (action = *p) != NULL; p = &action->next) {
                if (action->dev_id != dev_id)
                        continue;

                /* Found it - now free it */
                *p = action->next;
                kfree(action);
                goto out;
        }
        printk(KERN_ERR "Trying to free free IRQ%d\n",irq);
#ifdef CONFIG_DEBUG_ERRORS
        __backtrace();
#endif
out:
        spin_unlock_irqrestore(&irq_controller_lock, flags);
}

/* Start the interrupt probing.  Unlike other architectures,
 * we don't return a mask of interrupts from probe_irq_on,
 * but return the number of interrupts enabled for the probe.
 * The interrupts which have been enabled for probing is
 * instead recorded in the irq_desc structure.
 */
unsigned long probe_irq_on(void)
{
        unsigned int i, irqs = 0;
        unsigned long delay;

        /*
         * first snaffle up any unassigned but
         * probe-able interrupts
         */
        spin_lock_irq(&irq_controller_lock);
        for (i = 0; i < NR_IRQS; i++) {
                if (!irq_desc[i].valid ||
                    !irq_desc[i].probe_ok ||
                    irq_desc[i].action)
                        continue;

                irq_desc[i].probing = 1;
                irq_desc[i].triggered = 0;
                irq_desc[i].unmask(i);
                irqs += 1;
        }
        spin_unlock_irq(&irq_controller_lock);

        /*
         * wait for spurious interrupts to mask themselves out again
         */
        for (delay = jiffies + HZ/10; time_before(jiffies, delay); )
                /* min 100ms delay */;

        /*
         * now filter out any obviously spurious interrupts
         */
        spin_lock_irq(&irq_controller_lock);
        for (i = 0; i < NR_IRQS; i++) {
                if (irq_desc[i].probing &&
                    irq_desc[i].triggered) {
                        irq_desc[i].probing = 0;
                        irqs -= 1;
                }
        }
        spin_unlock_irq(&irq_controller_lock);

        /* now filter out any obviously spurious interrupts */
        return irqs;
}

/*
 * Possible return values:
 *  >= 0 - interrupt number
 *    -1 - no interrupt/many interrupts
 */
int probe_irq_off(unsigned long irqs)
{
        unsigned int i;
        int irq_found = NO_IRQ;

        /*
         * look at the interrupts, and find exactly one
         * that we were probing has been triggered
         */
        spin_lock_irq(&irq_controller_lock);
        for (i = 0; i < NR_IRQS; i++) {
                if (irq_desc[i].probing &&
                    irq_desc[i].triggered) {
                        if (irq_found != NO_IRQ) {
                                irq_found = NO_IRQ;
                                goto out;
                        }
                        irq_found = i;
                }
        }

        if (irq_found == -1)
                irq_found = NO_IRQ;
out:
        spin_unlock_irq(&irq_controller_lock);

        return irq_found;
}

void __init init_IRQ(void)
{
        extern void init_dma(void);
        int irq;

        for (irq = 0; irq < NR_IRQS; irq++) {
                irq_desc[irq].probe_ok = 0;
                irq_desc[irq].valid    = 0;
                irq_desc[irq].noautoenable = 0;
                irq_desc[irq].mask_ack = dummy_mask_unmask_irq;
                irq_desc[irq].mask     = dummy_mask_unmask_irq;
                irq_desc[irq].unmask   = dummy_mask_unmask_irq;
        }

        irq_init_irq();
#ifdef CONFIG_ARCH_ACORN
        init_FIQ();
#endif
        init_dma();
}