2 * linux/kernel/irq/autoprobe.c
4 * Copyright (C) 1992, 1998-2004 Linus Torvalds, Ingo Molnar
6 * This file contains the interrupt probing code and driver APIs.
10 #include <linux/module.h>
11 #include <linux/interrupt.h>
12 #include <linux/delay.h>
14 #include "internals.h"
17 * Autodetection depends on the fact that any interrupt that
18 * comes in on to an unassigned handler will get stuck with
19 * "IRQ_WAITING" cleared and the interrupt disabled.
21 static DEFINE_MUTEX(probing_active);
24 * probe_irq_on - begin an interrupt autodetect
26 * Commence probing for an interrupt. The interrupts are scanned
27 * and a mask of potential interrupt lines is returned.
30 unsigned long probe_irq_on(void)
32 struct irq_desc *desc;
36 mutex_lock(&probing_active);
38 * something may have generated an irq long ago and we want to
39 * flush such a longstanding irq before considering it as spurious.
41 for (i = nr_irqs-1; i > 0; i--) {
42 desc = irq_to_desc(i);
46 spin_lock_irq(&desc->lock);
47 if (!desc->action && !(desc->status & IRQ_NOPROBE)) {
49 * An old-style architecture might still have
50 * the handle_bad_irq handler there:
52 compat_irq_chip_set_default_handler(desc);
55 * Some chips need to know about probing in
58 if (desc->chip->set_type)
59 desc->chip->set_type(i, IRQ_TYPE_PROBE);
60 desc->chip->startup(i);
62 spin_unlock_irq(&desc->lock);
65 /* Wait for longstanding interrupts to trigger. */
69 * enable any unassigned irqs
70 * (we must startup again here because if a longstanding irq
71 * happened in the previous stage, it may have masked itself)
73 for (i = nr_irqs-1; i > 0; i--) {
74 desc = irq_to_desc(i);
78 spin_lock_irq(&desc->lock);
79 if (!desc->action && !(desc->status & IRQ_NOPROBE)) {
80 desc->status |= IRQ_AUTODETECT | IRQ_WAITING;
81 if (desc->chip->startup(i))
82 desc->status |= IRQ_PENDING;
84 spin_unlock_irq(&desc->lock);
88 * Wait for spurious interrupts to trigger
93 * Now filter out any obviously spurious interrupts
96 for (i = 0; i < nr_irqs; i++) {
99 desc = irq_to_desc(i);
102 spin_lock_irq(&desc->lock);
103 status = desc->status;
105 if (status & IRQ_AUTODETECT) {
106 /* It triggered already - consider it spurious. */
107 if (!(status & IRQ_WAITING)) {
108 desc->status = status & ~IRQ_AUTODETECT;
109 desc->chip->shutdown(i);
114 spin_unlock_irq(&desc->lock);
119 EXPORT_SYMBOL(probe_irq_on);
122 * probe_irq_mask - scan a bitmap of interrupt lines
123 * @val: mask of interrupts to consider
125 * Scan the interrupt lines and return a bitmap of active
126 * autodetect interrupts. The interrupt probe logic state
127 * is then returned to its previous value.
129 * Note: we need to scan all the irq's even though we will
130 * only return autodetect irq numbers - just so that we reset
131 * them all to a known state.
133 unsigned int probe_irq_mask(unsigned long val)
139 for (i = 0; i < nr_irqs; i++) {
140 struct irq_desc *desc = irq_to_desc(i);
145 spin_lock_irq(&desc->lock);
146 status = desc->status;
148 if (status & IRQ_AUTODETECT) {
149 if (i < 16 && !(status & IRQ_WAITING))
152 desc->status = status & ~IRQ_AUTODETECT;
153 desc->chip->shutdown(i);
155 spin_unlock_irq(&desc->lock);
157 mutex_unlock(&probing_active);
161 EXPORT_SYMBOL(probe_irq_mask);
164 * probe_irq_off - end an interrupt autodetect
165 * @val: mask of potential interrupts (unused)
167 * Scans the unused interrupt lines and returns the line which
168 * appears to have triggered the interrupt. If no interrupt was
169 * found then zero is returned. If more than one interrupt is
170 * found then minus the first candidate is returned to indicate
173 * The interrupt probe logic state is returned to its previous
176 * BUGS: When used in a module (which arguably shouldn't happen)
177 * nothing prevents two IRQ probe callers from overlapping. The
178 * results of this are non-optimal.
180 int probe_irq_off(unsigned long val)
182 int i, irq_found = 0, nr_irqs = 0;
184 for (i = 0; i < nr_irqs; i++) {
185 struct irq_desc *desc = irq_to_desc(i);
190 spin_lock_irq(&desc->lock);
191 status = desc->status;
193 if (status & IRQ_AUTODETECT) {
194 if (!(status & IRQ_WAITING)) {
199 desc->status = status & ~IRQ_AUTODETECT;
200 desc->chip->shutdown(i);
202 spin_unlock_irq(&desc->lock);
204 mutex_unlock(&probing_active);
207 irq_found = -irq_found;
211 EXPORT_SYMBOL(probe_irq_off);