gpioirq(4)
- NetBSD Manual Pages
GPIOIRQ(4) NetBSD Kernel Interfaces Manual GPIOIRQ(4)
NAME
gpioirq -- Install an interrupt handler on GPIO pins
SYNOPSIS
gpioirq* at gpio? offset 0 mask 0x1 flag 0x00
DESCRIPTION
The gpioirq driver attaches an interrupt handler to a one or more GPIO
pins.
The base pin number is specified in the kernel configuration file with
the offset locator. The mask locator can be 0x01 or greater to indicate
that more pins should have an interrupt handler attached to them.
The flag locator specifies the interrupt mode to use:
0x01 Interrupt on the positive (rising) edge of the pin.
0x02 Interrupt on the negative (falling) edge of the pin.
0x04 Interrupt on both edges of the pin.
0x08 Assert the intrerrupt as long as the pin is high.
0x10 Assert the interrupt as long as the pin is low.
Note that the interrupts modes are mutually-exclusive, and exactly one
interrupt mode must be specified. These flags correspond to the
GPIO_INTR mode bits defined in sys/gpio.h. In addition to the interrupt
mode, setting 0x1000 in flags will enable the printing of a message to
the console whenever the interrupt handler is called.
The offset, mask, and flag locators can also be specified when gpioirq is
attached at runtime using the GPIOATTACH ioctl(2) on the gpio(4) device.
FILES
/dev/gpioirqu GPIOIRQ device unit u file. The output from this device
are three uint8_t bytes every time an interrupt fires.
The bytes contain the device unit, pin number and the cur-
rent state of the pin.
EXAMPLES
The following example will output the device unit, pin and the pins cur-
rent state for pins 4, 5, 6, 7, 8, 9, 10, 11, 12 on gpio0:
/etc/gpio.conf contains:
gpio0 attach gpioirq 4 0x1ff 0x04
or a kernel was compiled to have the same parameters.
#!/usr/pkg/bin/perl
$dev = "/dev/gpioirq0";
sysopen(DEV,$dev,O_RDONLY) || die "sysopen: $!";
while (sysread(DEV,$b,3)) {
@v = unpack("CCC",$b);
print join(',',@v);
print "\n";
}
SEE ALSO
gpio(4), drvctl(8), gpioctl(8)
HISTORY
The gpioirq driver first appeared in NetBSD 9.0.
AUTHORS
The gpioirq driver was written by Brad Spencer <brad@anduin.eldar.org>.
BUGS
When an interrupt fires in most devices there is not any information car-
ried along in the interrupt as to whether or not the pin is high or low.
Hence the driver reads the current state of the pin after the interrupt
has fired and it is possible that the state of the pin could have changed
between the time the interrupt fired and the reading of the state. As a
practical matter the only time the pin state will be reported wrong is if
there is a very large number of interrupts happening. The driver could
have made some assumptions if the interrupt was only for a rising edge or
falling edge as in those cases it would be possible to know what the pin
state would have been, but in the case of the double edge, there really
will not be any way to be sure with most hardware and, in any case, the
gpio(4) infrastructure does not support getting at that information even
if it did exist.
It is important that if the gpioirq(4) device is opened that it be read,
as it may be possible to run the kernel out of memory if the device is
opened but not read and interrupts occur on a pin tied to the driver.
NetBSD 10.99 November 5, 2023 NetBSD 10.99
Powered by man-cgi (2024-03-20).
Maintained for NetBSD
by Kimmo Suominen.
Based on man-cgi by Panagiotis Christias.