参照元

説明

引数

返り値

参考

実装

/*
 * Internal function to register an irqaction - typically used to
 * allocate special interrupts that are part of the architecture.
 */
static int
__setup_irq(unsigned int irq, struct irq_desc *desc, struct irqaction *new)
{
	struct irqaction *old, **old_ptr;
	const char *old_name = NULL;
	unsigned long flags;
	int nested, shared = 0;
	int ret;

	if (!desc)
		return -EINVAL;

	if (desc->chip == &no_irq_chip)
		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 & IRQF_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);
	}
	/* Oneshot interrupts are not allowed with shared */
	if ((new->flags & IRQF_ONESHOT) && (new->flags & IRQF_SHARED))
		return -EINVAL;

	/*
	 * Check whether the interrupt nests into another interrupt
	 * thread.
	 */
	nested = desc->status & IRQ_NESTED_THREAD;
	if (nested) {
		if (!new->thread_fn)
			return -EINVAL;
		/*
		 * Replace the primary handler which was provided from
		 * the driver for non nested interrupt handling by the
		 * dummy function which warns when called.
		 */
		new->handler = irq_nested_primary_handler;
	}
	/*
	 * Create a handler thread when a thread function is supplied
	 * and the interrupt does not nest into another interrupt
	 * thread.
	 */
	if (new->thread_fn && !nested) {
		struct task_struct *t;

		t = kthread_create(irq_thread, new, "irq/%d-%s", irq,
				   new->name);
		if (IS_ERR(t))
			return PTR_ERR(t);
		/*
		 * We keep the reference to the task struct even if
		 * the thread dies to avoid that the interrupt code
		 * references an already freed task_struct.
		 */
		get_task_struct(t);
		new->thread = t;
	}

	/*
	 * The following block of code has to be executed atomically
	 */
	raw_spin_lock_irqsave(&desc->lock, flags);
	old_ptr = &desc->action;
	old = *old_ptr;
	if (old) {
		/*
		 * Can't share interrupts unless both agree to and are
		 * the same type (level, edge, polarity). So both flag
		 * fields must have IRQF_SHARED set and the bits which
		 * set the trigger type must match.
		 */
		if (!((old->flags & new->flags) & IRQF_SHARED) ||
		    ((old->flags ^ new->flags) & IRQF_TRIGGER_MASK)) {
			old_name = old->name;
			goto mismatch;
		}

#if defined(CONFIG_IRQ_PER_CPU)
		/* All handlers must agree on per-cpuness */
		if ((old->flags & IRQF_PERCPU) !=
		    (new->flags & IRQF_PERCPU))
			goto mismatch;
#endif

		/* add new interrupt at end of irq queue */
		do {
			old_ptr = &old->next;
			old = *old_ptr;
		} while (old);
		shared = 1;
	}

	if (!shared) {
		irq_chip_set_defaults(desc->chip);
		init_waitqueue_head(&desc->wait_for_threads);
		/* Setup the type (level, edge polarity) if configured: */
		if (new->flags & IRQF_TRIGGER_MASK) {
			ret = __irq_set_trigger(desc, irq,
					new->flags & IRQF_TRIGGER_MASK);

			if (ret)
				goto out_thread;
		} else
			compat_irq_chip_set_default_handler(desc);
#if defined(CONFIG_IRQ_PER_CPU)
		if (new->flags & IRQF_PERCPU)
			desc->status |= IRQ_PER_CPU;
#endif

		desc->status &= ~(IRQ_AUTODETECT | IRQ_WAITING | IRQ_ONESHOT |
				  IRQ_INPROGRESS | IRQ_SPURIOUS_DISABLED);

		if (new->flags & IRQF_ONESHOT)
			desc->status |= IRQ_ONESHOT;

		if (!(desc->status & IRQ_NOAUTOEN)) {
			desc->depth = 0;
			desc->status &= ~IRQ_DISABLED;
			desc->chip->startup(irq);
		} else
			/* Undo nested disables: */
			desc->depth = 1;

		/* Exclude IRQ from balancing if requested */
		if (new->flags & IRQF_NOBALANCING)
			desc->status |= IRQ_NO_BALANCING;

		/* Set default affinity mask once everything is setup */
		setup_affinity(irq, desc);
	} else if ((new->flags & IRQF_TRIGGER_MASK)
			&& (new->flags & IRQF_TRIGGER_MASK)
				!= (desc->status & IRQ_TYPE_SENSE_MASK)) {
		/* hope the handler works with the actual trigger mode... */
		pr_warning("IRQ %d uses trigger mode %d; requested %d\n",
				irq, (int)(desc->status & IRQ_TYPE_SENSE_MASK),
				(int)(new->flags & IRQF_TRIGGER_MASK));
	}

	new->irq = irq;
	*old_ptr = new;

	/* Reset broken irq detection when installing new handler */
	desc->irq_count = 0;
	desc->irqs_unhandled = 0;

	/*
	 * Check whether we disabled the irq via the spurious handler
	 * before. Reenable it and give it another chance.
	 */
	if (shared && (desc->status & IRQ_SPURIOUS_DISABLED)) {
		desc->status &= ~IRQ_SPURIOUS_DISABLED;
		__enable_irq(desc, irq, false);
	}
	raw_spin_unlock_irqrestore(&desc->lock, flags);
	/*
	 * Strictly no need to wake it up, but hung_task complains
	 * when no hard interrupt wakes the thread up.
	 */
	if (new->thread)
		wake_up_process(new->thread);
	register_irq_proc(irq, desc);
	new->dir = NULL;
	register_handler_proc(irq, new);
	return 0;

mismatch:
#ifdef CONFIG_DEBUG_SHIRQ
	if (!(new->flags & IRQF_PROBE_SHARED)) {
		printk(KERN_ERR "IRQ handler type mismatch for IRQ %d\n", irq);
		if (old_name)
			printk(KERN_ERR "current handler: %s\n", old_name);
		dump_stack();
	}
#endif
	ret = -EBUSY;

out_thread:
	raw_spin_unlock_irqrestore(&desc->lock, flags);
	if (new->thread) {
		struct task_struct *t = new->thread;

		new->thread = NULL;
		if (likely(!test_bit(IRQTF_DIED, &new->thread_flags)))
			kthread_stop(t);
		put_task_struct(t);
	}
	return ret;
}

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