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GPIOIRQ(4)                   Device Drivers 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
                    current state of the pin.

EXAMPLES
     The following example will output the device unit, pin and the pins
     current 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
     carried 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