path: root/kernel/irq/manage.c

/*
 * linux/kernel/irq/manage.c
 *
 * Copyright (C) 1992, 1998-2006 Linus Torvalds, Ingo Molnar
 * Copyright (C) 2005-2006 Thomas Gleixner
 *
 * This file contains driver APIs to the irq subsystem.
 */

#include <linux/irq.h>
#include <linux/module.h>
#include <linux/random.h>
#include <linux/interrupt.h>
#include <linux/slab.h>

#include "internals.h"

#ifdef CONFIG_SMP
cpumask_var_t irq_default_affinity;

static int init_irq_default_affinity(void)
{
	alloc_cpumask_var(&irq_default_affinity, GFP_KERNEL);
	cpumask_setall(irq_default_affinity);
	return 0;
}
core_initcall(init_irq_default_affinity);

/**
 *	synchronize_irq - wait for pending IRQ handlers (on other CPUs)
 *	@irq: interrupt number to wait for
 *
 *	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 synchronize_irq(unsigned int irq)
{
	struct irq_desc *desc = irq_to_desc(irq);
	unsigned int status;

	if (!desc)
		return;

	do {
		unsigned long flags;

		/*
		 * Wait until we're out of the critical section.  This might
		 * give the wrong answer due to the lack of memory barriers.
		 */
		while (desc->status & IRQ_INPROGRESS)
			cpu_relax();

		/* Ok, that indicated we're done: double-check carefully. */
		spin_lock_irqsave(&desc->lock, flags);
		status = desc->status;
		spin_unlock_irqrestore(&desc->lock, flags);

		/* Oops, that failed? */
	} while (status & IRQ_INPROGRESS);
}
EXPORT_SYMBOL(synchronize_irq);

/**
 *	irq_can_set_affinity - Check if the affinity of a given irq can be set
 *	@irq:		Interrupt to check
 *
 */
int irq_can_set_affinity(unsigned int irq)
{
	struct irq_desc *desc = irq_to_desc(irq);

	if (CHECK_IRQ_PER_CPU(desc->status) || !desc->chip ||
	    !desc->chip->set_affinity)
		return 0;

	return 1;
}

/**
 *	irq_set_affinity - Set the irq affinity of a given irq
 *	@irq:		Interrupt to set affinity
 *	@cpumask:	cpumask
 *
 */
int irq_set_affinity(unsigned int irq, const struct cpumask *cpumask)
{
	struct irq_desc *desc = irq_to_desc(irq);
	unsigned long flags;

	if (!desc->chip->set_affinity)
		return -EINVAL;

	spin_lock_irqsave(&desc->lock, flags);

#ifdef CONFIG_GENERIC_PENDING_IRQ
	if (desc->status & IRQ_MOVE_PCNTXT || desc->status & IRQ_DISABLED) {
		cpumask_copy(&desc->affinity, cpumask);
		desc->chip->set_affinity(irq, cpumask);
	} else {
		desc->status |= IRQ_MOVE_PENDING;
		cpumask_copy(&desc->pending_mask, cpumask);
	}
#else
	cpumask_copy(&desc->affinity, cpumask);
	desc->chip->set_affinity(irq, cpumask);
#endif
	desc->status |= IRQ_AFFINITY_SET;
	spin_unlock_irqrestore(&desc->lock, flags);
	return 0;
}

#ifndef CONFIG_AUTO_IRQ_AFFINITY
/*
 * Generic version of the affinity autoselector.
 */
int do_irq_select_affinity(unsigned int irq, struct irq_desc *desc)
{
	if (!irq_can_set_affinity(irq))
		return 0;

	/*
	 * Preserve an userspace affinity setup, but make sure that
	 * one of the targets is online.
	 */
	if (desc->status & (IRQ_AFFINITY_SET | IRQ_NO_BALANCING)) {
		if (cpumask_any_and(&desc->affinity, cpu_online_mask)
		    < nr_cpu_ids)
			goto set_affinity;
		else
			desc->status &= ~IRQ_AFFINITY_SET;
	}

	cpumask_and(&desc->affinity, cpu_online_mask, irq_default_affinity);
set_affinity:
	desc->chip->set_affinity(irq, &desc->affinity);

	return 0;
}
#else
static inline int do_irq_select_affinity(unsigned int irq, struct irq_desc *d)
{
	return irq_select_affinity(irq);
}
#endif

/*
 * Called when affinity is set via /proc/irq
 */
int irq_select_affinity_usr(unsigned int irq)
{
	struct irq_desc *desc = irq_to_desc(irq);
	unsigned long flags;
	int ret;

	spin_lock_irqsave(&desc->lock, flags);
	ret = do_irq_select_affinity(irq, desc);
	spin_unlock_irqrestore(&desc->lock, flags);

	return ret;
}

#else
static inline int do_irq_select_affinity(int irq, struct irq_desc *desc)
{
	return 0;
}
#endif

/**
 *	disable_irq_nosync - disable an irq without waiting
 *	@irq: Interrupt to disable
 *
 *	Disable the selected interrupt line.  Disables and Enables are
 *	nested.
 *	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 disable_irq_nosync(unsigned int irq)
{
	struct irq_desc *desc = irq_to_desc(irq);
	unsigned long flags;

	if (!desc)
		return;

	spin_lock_irqsave(&desc->lock, flags);
	if (!desc->depth++) {
		desc->status |= IRQ_DISABLED;
		desc->chip->disable(irq);
	}
	spin_unlock_irqrestore(&desc->lock, flags);
}
EXPORT_SYMBOL(disable_irq_nosync);

/**
 *	disable_irq - disable an irq and wait for completion
 *	@irq: Interrupt to disable
 *
 *	Disable the selected interrupt line.  Enables and Disables are
 *	nested.
 *	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)
{
	struct irq_desc *desc = irq_to_desc(irq);

	if (!desc)
		return;

	disable_irq_nosync(irq);
	if (desc->action)
		synchronize_irq(irq);
}
EXPORT_SYMBOL(disable_irq);

static void __enable_irq(struct irq_desc *desc, unsigned int irq)
{
	switch (desc->depth) {
	case 0:
		WARN(1, KERN_WARNING "Unbalanced enable for IRQ %d\n", irq);
		break;
	case 1: {
		unsigned int status = desc->status & ~IRQ_DISABLED;

		/* Prevent probing on this irq: */
		desc->status = status | IRQ_NOPROBE;
		check_irq_resend(desc, irq);
		/* fall-through */
	}
	default:
		desc->depth--;
	}
}

/**
 *	enable_irq - enable handling of an irq
 *	@irq: Interrupt to enable
 *
 *	Undoes the effect of one call to disable_irq().  If this
 *	matches the last disable, processing of interrupts on this
 *	IRQ line is re-enabled.
 *
 *	This function may be called from IRQ context.
 */
void enable_irq(unsigned int irq)
{
	struct irq_desc *desc = irq_to_desc(