PROBE_IRQ_ON(9) Linux Kernel Functions PROBE_IRQ_ON(9)NAME
probe_irq_on, probe_irq_off - safe probing for IRQs
SYNOPSIS
#include <linux/interrupt.h>
unsigned long probe_irq_on(void)
int probe_irq_off(unsigned long irqs);
DESCRIPTION
Usage
probe_irq_on() turns on IRQ detection. It operates by enabling all
interrupts which have no handlers, while keeping the handlers for those
interrupts NULL. The kernel's generic interrupt handling routine will
disable these IRQs when an interrupt is received on them.
probe_irq_on() adds each of these IRQ numbers to a vector which it will
return. It waits approximately 100ms for any spurious interrupts that
may occur, and masks these from its vector; it then returns this vector
to its caller.
probe_irq_off() tests an internal list of enabled IRQs against its irqs
parameter, which should be the value returned by the last
probe_irq_on(). This function basically detects which IRQs have been
switched off, and thus which ones have received interrupts.
Example
This explanation may seem a bit confusing, so here is an example of
code the mythical FUBAR 2000 driver could use to probe for IRQs:
unsigned long irqs;
int irq;
irqs = probe_irq_on();
outb(FB2K_GIVE_ME_AN_INTERRUPT_OR_GIVE_ME_DEATH,
FB2K_CONTROL_PORT);
/* the interrupt could take a while to occur */
udelay(1000);
irq = probe_irq_off(irqs);
if (irq == 0) {
printk("fb2k: could not detect IRQ.\n");
printk("fb2k: Installation failed.\n");
} else if (irq == -1) {
printk("fb2k: multiple IRQs detected.\n");
printk("fb2k: Installation failed.\n");
} else {
fb2k_dev->irq = irq;
printk("fb2k: using probed IRQ %d.\n", irq);
}
RETURN VALUEprobe_irq_on() returns a bitmap of all unhandled IRQs (except those
which are receiving spurious interrupts). This value should only be
used as a parameter to the next call to probe_irq_off().
probe_irq_off() returns the IRQ number of whichever unhandled interrupt
has occurred since the last probe_irq_on(). If no interrupts have
occurred on any of the marked IRQs, 0 is returned; if interrupts have
occurred on more than one of these IRQs, -1 is returned.
AVAILABILITY
Linux 1.2+. These functions are not available on m68k-based machines.
SEE ALSOrequest_irq(9)
arch/*/kernel/irq.c
AUTHOR
Neil Moore <amethyst@maxwell.ml.org>
BUGS
As mentioned above, these functions are not available on m68k-based
machines.
This manpage is way too confusing.
Linux DDI 2.1.47 1997/08/14 07:53:32 PROBE_IRQ_ON(9)
