linux/kernel/irq/autoprobe.c

// SPDX-License-Identifier: GPL-2.0
/*
 * Copyright (C) 1992, 1998-2004 Linus Torvalds, Ingo Molnar
 *
 * This file contains the interrupt probing code and driver APIs.
 */

#include <linux/irq.h>
#include <linux/module.h>
#include <linux/interrupt.h>
#include <linux/delay.h>
#include <linux/async.h>

#include "internals.h"

/*
 * Autodetection depends on the fact that any interrupt that
 * comes in on to an unassigned handler will get stuck with
 * "IRQS_WAITING" cleared and the interrupt disabled.
 */
static DEFINE_MUTEX(probing_active);

/**
 *	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.
 *
 */
unsigned long probe_irq_on(void)
{ … }
EXPORT_SYMBOL(…);

/**
 *	probe_irq_mask - scan a bitmap of interrupt lines
 *	@val:	mask of interrupts to consider
 *
 *	Scan the interrupt lines and return a bitmap of active
 *	autodetect interrupts. The interrupt probe logic state
 *	is then returned to its previous value.
 *
 *	Note: we need to scan all the irq's even though we will
 *	only return autodetect irq numbers - just so that we reset
 *	them all to a known state.
 */
unsigned int probe_irq_mask(unsigned long val)
{ … }
EXPORT_SYMBOL(…);

/**
 *	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 shouldn't happen)
 *	nothing prevents two IRQ probe callers from overlapping. The
 *	results of this are non-optimal.
 */
int probe_irq_off(unsigned long val)
{ … }
EXPORT_SYMBOL(…);