irq.c

linux-2.4.29操作系统的源码

{
	unsigned long eirr_val;
	unsigned int i=3;	/* limit time in interrupt context */

	/*
	 * PSW_I or EIEM bits cannot be enabled until after the
	 * interrupts are processed.
	 * timer_interrupt() assumes it won't get interrupted when it
	 * holds the xtime_lock...an unmasked interrupt source could
	 * interrupt and deadlock by trying to grab xtime_lock too.
	 * Keeping PSW_I and EIEM disabled avoids this.
	 */
	set_eiem(0UL);	/* disable all extr interrupt for now */

	/* 1) only process IRQs that are enabled/unmasked (cpu_eiem)
	 * 2) We loop here on EIRR contents in order to avoid
	 *    nested interrupts or having to take another interupt
	 *    when we could have just handled it right away.
	 * 3) Limit the number of times we loop to make sure other
	 *    processing can occur.
	 */
	while ((eirr_val = (mfctl(23) & cpu_eiem)) && --i) {
		unsigned long bit = (1UL<<MAX_CPU_IRQ);
		unsigned int irq;

		mtctl(eirr_val, 23); /* reset bits we are going to process */

#ifdef DEBUG_IRQ
		if (eirr_val != (1UL << MAX_CPU_IRQ))
			printk(KERN_DEBUG "do_cpu_irq_mask  %x\n", eirr_val);
#endif

		for (irq = 0; eirr_val && bit; bit>>=1, irq++)
		{
			if (!(bit&eirr_val&cpu_eiem))
				continue;

			/* clear bit in mask - can exit loop sooner */
			eirr_val &= ~bit;

			do_irq(&cpu_irq_actions[irq], TIMER_IRQ+irq, regs);
		}
	}
	set_eiem(cpu_eiem);
}


/* Called from second level IRQ regions: eg dino or iosapic. */
void do_irq_mask(unsigned long mask, struct irq_region *region, struct pt_regs *regs)
{
	unsigned long bit;
	unsigned int irq;

#ifdef DEBUG_IRQ
	if (mask != (1L<<MAX_CPU_IRQ))
	    printk(KERN_DEBUG "do_irq_mask %08lx %p %p\n", mask, region, regs);
#endif

	for (bit = (1L<<MAX_CPU_IRQ), irq = 0; mask && bit; bit>>=1, irq++) {
		unsigned int irq_num;
		if (!(bit&mask))
			continue;

		mask &= ~bit;	/* clear bit in mask - can exit loop sooner */
		irq_num = region->data.irqbase + irq;

		mask_irq(irq_num);
		do_irq(&region->action[irq], irq_num, regs);
		unmask_irq(irq_num);
	}
}


static inline int find_free_region(void)
{
	int irqreg;

	for (irqreg=1; irqreg <= (NR_IRQ_REGS); irqreg++) {
		if (irq_region[irqreg] == NULL)
			return irqreg;
	}

	return 0;
}


/*****
 * alloc_irq_region - allocate/init a new IRQ region
 * @count: number of IRQs in this region.
 * @ops: function table with request/release/mask/unmask/etc.. entries.
 * @name: name of region owner for /proc/interrupts output.
 * @dev: private data to associate with the new IRQ region.
 *
 * Every IRQ must become a MMIO write to the CPU's EIRR in
 * order to get CPU service. The IRQ region represents the
 * number of unique events the region handler can (or must)
 * identify. For PARISC CPU, that's the width of the EIR Register.
 * IRQ regions virtualize IRQs (eg EISA or PCI host bus controllers)
 * for line based devices.
 */
struct irq_region *alloc_irq_region( int count, struct irq_region_ops *ops,
					const char *name, void *dev)
{
	struct irq_region *region;
	int index;

	index = find_free_region();
	if (index == 0) {
		printk(KERN_ERR "Maximum number of irq regions exceeded. Increase NR_IRQ_REGS!\n");
		return NULL;
	}

	if ((IRQ_REGION(count-1)))
		return NULL;

	if (count < IRQ_PER_REGION) {
	    DBG_IRQ(0, ("alloc_irq_region() using minimum of %d irq lines for %s (%d)\n",
			IRQ_PER_REGION, name, count));
	    count = IRQ_PER_REGION;
	}

	/* if either mask *or* unmask is set, both have to be set. */
	if((ops->mask_irq || ops->unmask_irq) &&
		!(ops->mask_irq && ops->unmask_irq))
			return NULL;

	/* ditto for enable/disable */
	if( (ops->disable_irq || ops->enable_irq) &&
		!(ops->disable_irq && ops->enable_irq) )
			return NULL;

	region = kmalloc(sizeof(*region), GFP_ATOMIC);
	if (!region)
		return NULL;
	memset(region, 0, sizeof(*region));

	region->action = kmalloc(count * sizeof(*region->action), GFP_ATOMIC);
	if (!region->action) {
		kfree(region);
		return NULL;
	}
	memset(region->action, 0, count * sizeof(*region->action));

	region->ops = *ops;
	region->data.irqbase = IRQ_FROM_REGION(index);
	region->data.name = name;
	region->data.dev = dev;

	irq_region[index] = region;

	return irq_region[index];
}

/* FIXME: SMP, flags, bottom halves, rest */

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

#if 0
	printk(KERN_INFO "request_irq(%d, %p, 0x%lx, %s, %p)\n",irq, handler, irqflags, devname, dev_id);
#endif

	irq = irq_cannonicalize(irq);
	/* request_irq()/free_irq() may not be called from interrupt context. */
	if (in_interrupt())
		BUG();

	if (!handler) {
		printk(KERN_ERR "request_irq(%d,...): Augh! No handler for irq!\n",
			irq);
		return -EINVAL;
	}

	if (irq_region[IRQ_REGION(irq)] == NULL) {
		/*
		** Bug catcher for drivers which use "char" or u8 for
		** the IRQ number. They lose the region number which
		** is in pcidev->irq (an int).
		*/
		printk(KERN_ERR "%p (%s?) called request_irq with an invalid irq %d\n",
			__builtin_return_address(0), devname, irq);
		return -EINVAL;
	}

	spin_lock(&irq_lock);
	action = &(irq_region[IRQ_REGION(irq)]->action[IRQ_OFFSET(irq)]);

	/* First one is preallocated. */
	if (action->handler) {
		/* But it's in use...find the tail and allocate a new one */
		while (action->next)
			action = action->next;

		action->next = kmalloc(sizeof(*action), GFP_ATOMIC);
		memset(action->next, 0, sizeof(*action));

		action = action->next;
	}

	if (!action) {
		spin_unlock(&irq_lock);
		printk(KERN_ERR "request_irq(): Augh! No action!\n") ;
		return -ENOMEM;
	}

	action->handler = handler;
	action->flags = irqflags;
	action->mask = 0;
	action->name = devname;
	action->next = NULL;
	action->dev_id = dev_id;
	spin_unlock(&irq_lock);

	enable_irq(irq);
	return 0;
}

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

	/* See comments in request_irq() about interrupt context */
	irq = irq_cannonicalize(irq);
	
	if (in_interrupt()) BUG();

	spin_lock(&irq_lock);
	action = &irq_region[IRQ_REGION(irq)]->action[IRQ_OFFSET(irq)];

	if (action->dev_id == dev_id) {
		if (action->next == NULL) {
			action->handler = NULL;
		} else {
			memcpy(action, action->next, sizeof(*action));
		}

		spin_unlock(&irq_lock);
		return;
	}

	p = &action->next;
	action = action->next;

	for (; (action = *p) != NULL; p = &action->next) {
		if (action->dev_id != dev_id)
			continue;

		/* Found it - now free it */
		*p = action->next;
		kfree(action);

		spin_unlock(&irq_lock);
		return;
	}

	spin_unlock(&irq_lock);
	printk(KERN_ERR "Trying to free free IRQ%d\n",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.
 *
 */

/* TODO: spin_lock_irq(desc->lock -> irq_lock) */

unsigned long probe_irq_on(void)
{
	unsigned int i;
	unsigned long val;
	unsigned long delay;
	struct irq_region *region;

	/* support for irq autoprobing is limited to EISA (irq region 0) */
	region = irq_region[EISA_IRQ_REGION];
	if (!EISA_bus || !region)
		return 0;

	down(&probe_sem);

	/*
	 * 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 = EISA_MAX_IRQS-1; i > 0; i--) {
		struct irqaction *action;
		
		spin_lock_irq(&irq_lock);
		action = region->action + i;
		if (!action->handler) {
			region->data.status[i] |= IRQ_AUTODETECT | IRQ_WAITING;
			region->ops.enable_irq(region->data.dev,i);
		}
		spin_unlock_irq(&irq_lock);
	}

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

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

		spin_lock_irq(&irq_lock);
		status = region->data.status[i];

		if (status & IRQ_AUTODETECT) {
			/* It triggered already - consider it spurious. */
			if (!(status & IRQ_WAITING)) {
				region->data.status[i] = status & ~IRQ_AUTODETECT;
				region->ops.disable_irq(region->data.dev,i);
			} else
				if (i < BITS_PER_LONG)
					val |= (1 << i);
		}
		spin_unlock_irq(&irq_lock);
	}

	return 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)
{
        struct irq_region *region;
	int i, irq_found, nr_irqs;

        /* support for irq autoprobing is limited to EISA (irq region 0) */
        region = irq_region[EISA_IRQ_REGION];
        if (!EISA_bus || !region)
		return 0;

	nr_irqs = 0;
	irq_found = 0;
	for (i = 0; i < EISA_MAX_IRQS; i++) {
		unsigned int status;
		
		spin_lock_irq(&irq_lock);
		status = region->data.status[i];

                if (status & IRQ_AUTODETECT) {
			if (!(status & IRQ_WAITING)) {
				if (!nr_irqs)
					irq_found = i;
				nr_irqs++;
			}
			region->ops.disable_irq(region->data.dev,i);
			region->data.status[i] = status & ~IRQ_AUTODETECT;
		}
		spin_unlock_irq(&irq_lock);
	}
	up(&probe_sem);

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


void __init init_IRQ(void)
{
	local_irq_disable();	/* PARANOID - should already be disabled */
	mtctl(-1L, 23);		/* EIRR : clear all pending external intr */
#ifdef CONFIG_SMP
	if (!cpu_eiem)
		cpu_eiem = EIEM_MASK(IPI_IRQ) | EIEM_MASK(TIMER_IRQ);
#else
	cpu_eiem = EIEM_MASK(TIMER_IRQ);
#endif
        set_eiem(cpu_eiem);	/* EIEM : enable all external intr */

}

#ifdef CONFIG_PROC_FS
/* called from kernel/sysctl.c:sysctl_init() */
void __init init_irq_proc(void)
{
}
#endif