irq.c

linux-2.6.15.6

		handle = do_bad_IRQ;

	desc = irq_desc + irq;

	if (is_chained && desc->chip == &bad_chip)
		printk(KERN_WARNING "Trying to install chained handler for IRQ%d\n", irq);

	spin_lock_irqsave(&irq_controller_lock, flags);
	if (handle == do_bad_IRQ) {
		desc->chip->mask(irq);
		desc->chip->ack(irq);
		desc->depth = 1;
		desc->enabled = 0;
	}
	desc->handle = handle;
	if (handle != do_bad_IRQ && is_chained) {
		desc->valid = 0;
		desc->probe_ok = 0;
		desc->depth = 0;
		desc->chip->unmask(irq);
	}
	spin_unlock_irqrestore(&irq_controller_lock, flags);
}

void set_irq_chip(unsigned int irq, struct irqchip *chip)
{
	struct irqdesc *desc;
	unsigned long flags;

	if (irq >= NR_IRQS) {
		printk(KERN_ERR "Trying to install chip for IRQ%d\n", irq);
		return;
	}

	if (chip == NULL)
		chip = &bad_chip;

	desc = irq_desc + irq;
	spin_lock_irqsave(&irq_controller_lock, flags);
	desc->chip = chip;
	spin_unlock_irqrestore(&irq_controller_lock, flags);
}

int set_irq_type(unsigned int irq, unsigned int type)
{
	struct irqdesc *desc;
	unsigned long flags;
	int ret = -ENXIO;

	if (irq >= NR_IRQS) {
		printk(KERN_ERR "Trying to set irq type for IRQ%d\n", irq);
		return -ENODEV;
	}

	desc = irq_desc + irq;
	if (desc->chip->type) {
		spin_lock_irqsave(&irq_controller_lock, flags);
		ret = desc->chip->type(irq, type);
		spin_unlock_irqrestore(&irq_controller_lock, flags);
	}

	return ret;
}

void set_irq_flags(unsigned int irq, unsigned int iflags)
{
	struct irqdesc *desc;
	unsigned long flags;

	if (irq >= NR_IRQS) {
		printk(KERN_ERR "Trying to set irq flags for IRQ%d\n", irq);
		return;
	}

	desc = irq_desc + irq;
	spin_lock_irqsave(&irq_controller_lock, flags);
	desc->valid = (iflags & IRQF_VALID) != 0;
	desc->probe_ok = (iflags & IRQF_PROBE) != 0;
	desc->noautoenable = (iflags & IRQF_NOAUTOEN) != 0;
	spin_unlock_irqrestore(&irq_controller_lock, flags);
}

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

	/*
	 * 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
	 */
	desc = irq_desc + irq;
	spin_lock_irqsave(&irq_controller_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(&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) {
 		desc->probing = 0;
		desc->running = 0;
		desc->pending = 0;
		desc->depth = 1;
		if (!desc->noautoenable) {
			desc->depth = 0;
			desc->enabled = 1;
			desc->chip->unmask(irq);
		}
	}

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

/**
 *	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
 *
 */

//FIXME - handler used to return void - whats the significance of the change?
int request_irq(unsigned int irq, irqreturn_t (*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 ||
	    (irq_flags & SA_SHIRQ && !dev_id))
		return -EINVAL;

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

	action->handler = handler;
	action->flags = irq_flags;
	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.
 *
 *	This function may be called from interrupt context.
 */
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);
}

EXPORT_SYMBOL(free_irq);

/* 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].probe_ok || irq_desc[i].action)
			continue;

		irq_desc[i].probing = 1;
		irq_desc[i].triggered = 0;
		if (irq_desc[i].chip->type)
			irq_desc[i].chip->type(i, IRQT_PROBE);
		irq_desc[i].chip->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);

	return irqs;
}

EXPORT_SYMBOL(probe_irq_on);

/*
 * 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;
}

EXPORT_SYMBOL(probe_irq_off);

void __init init_irq_proc(void)
{
}

void __init init_IRQ(void)
{
	struct irqdesc *desc;
	extern void init_dma(void);
	int irq;

	for (irq = 0, desc = irq_desc; irq < NR_IRQS; irq++, desc++)
		*desc = bad_irq_desc;

	arc_init_irq();
	init_dma();
}