// SPDX-License-Identifier: GPL-2.0
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/*
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* Copyright (C) 1992, 1998-2004 Linus Torvalds, Ingo Molnar
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*
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* This file contains the interrupt probing code and driver APIs.
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*/
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#include <linux/irq.h>
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#include <linux/module.h>
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#include <linux/interrupt.h>
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#include <linux/delay.h>
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#include <linux/async.h>
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#include "internals.h"
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/*
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* Autodetection depends on the fact that any interrupt that
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* comes in on to an unassigned handler will get stuck with
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* "IRQS_WAITING" cleared and the interrupt disabled.
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*/
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static DEFINE_MUTEX(probing_active);
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/**
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* probe_irq_on - begin an interrupt autodetect
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*
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* Commence probing for an interrupt. The interrupts are scanned
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* and a mask of potential interrupt lines is returned.
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*
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*/
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unsigned long probe_irq_on(void)
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{
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struct irq_desc *desc;
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unsigned long mask = 0;
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int i;
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/*
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* quiesce the kernel, or at least the asynchronous portion
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*/
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async_synchronize_full();
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mutex_lock(&probing_active);
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/*
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* something may have generated an irq long ago and we want to
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* flush such a longstanding irq before considering it as spurious.
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*/
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for_each_irq_desc_reverse(i, desc) {
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raw_spin_lock_irq(&desc->lock);
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if (!desc->action && irq_settings_can_probe(desc)) {
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/*
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* Some chips need to know about probing in
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* progress:
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*/
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if (desc->irq_data.chip->irq_set_type)
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desc->irq_data.chip->irq_set_type(&desc->irq_data,
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IRQ_TYPE_PROBE);
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irq_activate_and_startup(desc, IRQ_NORESEND);
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}
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raw_spin_unlock_irq(&desc->lock);
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}
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/* Wait for longstanding interrupts to trigger. */
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msleep(20);
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/*
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* enable any unassigned irqs
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* (we must startup again here because if a longstanding irq
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* happened in the previous stage, it may have masked itself)
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*/
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for_each_irq_desc_reverse(i, desc) {
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raw_spin_lock_irq(&desc->lock);
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if (!desc->action && irq_settings_can_probe(desc)) {
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desc->istate |= IRQS_AUTODETECT | IRQS_WAITING;
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if (irq_activate_and_startup(desc, IRQ_NORESEND))
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desc->istate |= IRQS_PENDING;
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}
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raw_spin_unlock_irq(&desc->lock);
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}
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/*
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* Wait for spurious interrupts to trigger
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*/
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msleep(100);
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/*
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* Now filter out any obviously spurious interrupts
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*/
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for_each_irq_desc(i, desc) {
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raw_spin_lock_irq(&desc->lock);
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if (desc->istate & IRQS_AUTODETECT) {
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/* It triggered already - consider it spurious. */
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if (!(desc->istate & IRQS_WAITING)) {
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desc->istate &= ~IRQS_AUTODETECT;
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irq_shutdown_and_deactivate(desc);
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} else
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if (i < 32)
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mask |= 1 << i;
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}
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raw_spin_unlock_irq(&desc->lock);
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}
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return mask;
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}
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EXPORT_SYMBOL(probe_irq_on);
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/**
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* probe_irq_mask - scan a bitmap of interrupt lines
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* @val: mask of interrupts to consider
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*
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* Scan the interrupt lines and return a bitmap of active
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* autodetect interrupts. The interrupt probe logic state
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* is then returned to its previous value.
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*
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* Note: we need to scan all the irq's even though we will
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* only return autodetect irq numbers - just so that we reset
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* them all to a known state.
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*/
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unsigned int probe_irq_mask(unsigned long val)
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{
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unsigned int mask = 0;
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struct irq_desc *desc;
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int i;
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for_each_irq_desc(i, desc) {
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raw_spin_lock_irq(&desc->lock);
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if (desc->istate & IRQS_AUTODETECT) {
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if (i < 16 && !(desc->istate & IRQS_WAITING))
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mask |= 1 << i;
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desc->istate &= ~IRQS_AUTODETECT;
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irq_shutdown_and_deactivate(desc);
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}
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raw_spin_unlock_irq(&desc->lock);
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}
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mutex_unlock(&probing_active);
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return mask & val;
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}
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EXPORT_SYMBOL(probe_irq_mask);
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/**
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* probe_irq_off - end an interrupt autodetect
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* @val: mask of potential interrupts (unused)
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*
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* Scans the unused interrupt lines and returns the line which
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* appears to have triggered the interrupt. If no interrupt was
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* found then zero is returned. If more than one interrupt is
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* found then minus the first candidate is returned to indicate
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* their is doubt.
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*
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* The interrupt probe logic state is returned to its previous
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* value.
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*
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* BUGS: When used in a module (which arguably shouldn't happen)
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* nothing prevents two IRQ probe callers from overlapping. The
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* results of this are non-optimal.
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*/
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int probe_irq_off(unsigned long val)
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{
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int i, irq_found = 0, nr_of_irqs = 0;
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struct irq_desc *desc;
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for_each_irq_desc(i, desc) {
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raw_spin_lock_irq(&desc->lock);
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if (desc->istate & IRQS_AUTODETECT) {
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if (!(desc->istate & IRQS_WAITING)) {
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if (!nr_of_irqs)
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irq_found = i;
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nr_of_irqs++;
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}
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desc->istate &= ~IRQS_AUTODETECT;
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irq_shutdown_and_deactivate(desc);
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}
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raw_spin_unlock_irq(&desc->lock);
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}
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mutex_unlock(&probing_active);
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if (nr_of_irqs > 1)
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irq_found = -irq_found;
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return irq_found;
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}
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EXPORT_SYMBOL(probe_irq_off);
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