| // SPDX-License-Identifier: GPL-2.0 |
| /* |
| * linux/kernel/irq/autoprobe.c |
| * |
| * 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) |
| { |
| struct irq_desc *desc; |
| unsigned long mask = 0; |
| int i; |
| |
| /* |
| * quiesce the kernel, or at least the asynchronous portion |
| */ |
| async_synchronize_full(); |
| mutex_lock(&probing_active); |
| /* |
| * something may have generated an irq long ago and we want to |
| * flush such a longstanding irq before considering it as spurious. |
| */ |
| for_each_irq_desc_reverse(i, desc) { |
| raw_spin_lock_irq(&desc->lock); |
| if (!desc->action && irq_settings_can_probe(desc)) { |
| /* |
| * Some chips need to know about probing in |
| * progress: |
| */ |
| if (desc->irq_data.chip->irq_set_type) |
| desc->irq_data.chip->irq_set_type(&desc->irq_data, |
| IRQ_TYPE_PROBE); |
| irq_activate_and_startup(desc, IRQ_NORESEND); |
| } |
| raw_spin_unlock_irq(&desc->lock); |
| } |
| |
| /* Wait for longstanding interrupts to trigger. */ |
| msleep(20); |
| |
| /* |
| * enable any unassigned irqs |
| * (we must startup again here because if a longstanding irq |
| * happened in the previous stage, it may have masked itself) |
| */ |
| for_each_irq_desc_reverse(i, desc) { |
| raw_spin_lock_irq(&desc->lock); |
| if (!desc->action && irq_settings_can_probe(desc)) { |
| desc->istate |= IRQS_AUTODETECT | IRQS_WAITING; |
| if (irq_startup(desc, IRQ_NORESEND, IRQ_START_FORCE)) |
| desc->istate |= IRQS_PENDING; |
| } |
| raw_spin_unlock_irq(&desc->lock); |
| } |
| |
| /* |
| * Wait for spurious interrupts to trigger |
| */ |
| msleep(100); |
| |
| /* |
| * Now filter out any obviously spurious interrupts |
| */ |
| for_each_irq_desc(i, desc) { |
| raw_spin_lock_irq(&desc->lock); |
| |
| if (desc->istate & IRQS_AUTODETECT) { |
| /* It triggered already - consider it spurious. */ |
| if (!(desc->istate & IRQS_WAITING)) { |
| desc->istate &= ~IRQS_AUTODETECT; |
| irq_shutdown(desc); |
| } else |
| if (i < 32) |
| mask |= 1 << i; |
| } |
| raw_spin_unlock_irq(&desc->lock); |
| } |
| |
| return mask; |
| } |
| EXPORT_SYMBOL(probe_irq_on); |
| |
| /** |
| * 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) |
| { |
| unsigned int mask = 0; |
| struct irq_desc *desc; |
| int i; |
| |
| for_each_irq_desc(i, desc) { |
| raw_spin_lock_irq(&desc->lock); |
| if (desc->istate & IRQS_AUTODETECT) { |
| if (i < 16 && !(desc->istate & IRQS_WAITING)) |
| mask |= 1 << i; |
| |
| desc->istate &= ~IRQS_AUTODETECT; |
| irq_shutdown(desc); |
| } |
| raw_spin_unlock_irq(&desc->lock); |
| } |
| mutex_unlock(&probing_active); |
| |
| return mask & val; |
| } |
| EXPORT_SYMBOL(probe_irq_mask); |
| |
| /** |
| * 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) |
| { |
| int i, irq_found = 0, nr_of_irqs = 0; |
| struct irq_desc *desc; |
| |
| for_each_irq_desc(i, desc) { |
| raw_spin_lock_irq(&desc->lock); |
| |
| if (desc->istate & IRQS_AUTODETECT) { |
| if (!(desc->istate & IRQS_WAITING)) { |
| if (!nr_of_irqs) |
| irq_found = i; |
| nr_of_irqs++; |
| } |
| desc->istate &= ~IRQS_AUTODETECT; |
| irq_shutdown(desc); |
| } |
| raw_spin_unlock_irq(&desc->lock); |
| } |
| mutex_unlock(&probing_active); |
| |
| if (nr_of_irqs > 1) |
| irq_found = -irq_found; |
| |
| return irq_found; |
| } |
| EXPORT_SYMBOL(probe_irq_off); |
| |