--- /dev/null
+/*
+ * 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_startup(desc, false);
+ }
+ 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, false))
+ 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);
+
Code Review / kvmfornfv.git / blobdiff