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/*
* 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>
/*
* Autodetection depends on the fact that any interrupt that
* comes in on to an unassigned handler will get stuck with
* "IRQ_WAITING" cleared and the interrupt disabled.
*/
static DECLARE_MUTEX(probe_sem);
/**
* 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)
{
unsigned long val;
irq_desc_t *desc;
unsigned int i;
down(&probe_sem);
/*
* something may have generated an irq long ago and we want to
* flush such a longstanding irq before considering it as spurious.
*/
for (i = NR_IRQS-1; i > 0; i--) {
desc = irq_desc + i;
spin_lock_irq(&desc->lock);
if (!irq_desc[i].action)
irq_desc[i].handler->startup(i);
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 (i = NR_IRQS-1; i > 0; i--) {
desc = irq_desc + i;
spin_lock_irq(&desc->lock);
if (!desc->action) {
desc->status |= IRQ_AUTODETECT | IRQ_WAITING;
if (desc->handler->startup(i))
desc->status |= IRQ_PENDING;
}
spin_unlock_irq(&desc->lock);
}
/*
* Wait for spurious interrupts to trigger
*/
msleep(100);
/*
* Now filter out any obviously spurious interrupts
*/
val = 0;
for (i = 0; i < NR_IRQS; i++) {
irq_desc_t *desc = irq_desc + i;
unsigned int status;
spin_lock_irq(&desc->lock);
status = desc->status;
if (status & IRQ_AUTODETECT) {
/* It triggered already - consider it spurious. */
if (!(status & IRQ_WAITING)) {
desc->status = status & ~IRQ_AUTODETECT;
desc->handler->shutdown(i);
} else
if (i < 32)
val |= 1 << i;
}
spin_unlock_irq(&desc->lock);
}
return val;
}
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;
int i;
mask = 0;
for (i = 0; i < NR_IRQS; i++) {
irq_desc_t *desc = irq_desc + i;
unsigned int status;
spin_lock_irq(&desc->lock);
status = desc->status;
if (status & IRQ_AUTODETECT) {
if (i < 16 && !(status & IRQ_WAITING))
mask |= 1 << i;
desc->status = status & ~IRQ_AUTODETECT;
desc->handler->shutdown(i);
}
spin_unlock_irq(&desc->lock);
}
up(&probe_sem);
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_irqs = 0;
for (i = 0; i < NR_IRQS; i++) {
irq_desc_t *desc = irq_desc + i;
unsigned int status;
spin_lock_irq(&desc->lock);
status = desc->status;
if (status & IRQ_AUTODETECT) {
if (!(status & IRQ_WAITING)) {
if (!nr_irqs)
irq_found = i;
nr_irqs++;
}
desc->status = status & ~IRQ_AUTODETECT;
desc->handler->shutdown(i);
}
spin_unlock_irq(&desc->lock);
}
up(&probe_sem);
if (nr_irqs > 1)
irq_found = -irq_found;
return irq_found;
}
EXPORT_SYMBOL(probe_irq_off);
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