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GPIO(4)		       FreeBSD Kernel Interfaces Manual		       GPIO(4)

     gpio -- General Purpose Input/Output

     gpio* at ath?
     gpio* at bcmgpio? (arm64, armv7)
     gpio* at elansc? (i386)
     gpio* at glxpcib? (i386)
     gpio* at gscpcib? (i386)
     gpio* at isagpio?
     gpio* at nsclpcsio?
     gpio* at omgpio? (armv7)
     gpio* at pcagpio?
     gpio* at pcaled?
     gpio* at skgpio? (amd64, i386)
     gpio* at sxipio? (arm64, armv7)
     gpio0 at voyager? (loongson)

     #include <sys/types.h>
     #include <sys/gpio.h>
     #include <sys/ioctl.h>

     The gpio device attaches to the GPIO controller and provides a uniform
     programming interface to its pins.

     Each GPIO controller with an attached gpio	device has an associated de-
     vice file under the /dev directory, e.g. /dev/gpio0.  Access from user-
     land is performed through ioctl(2)	calls on these devices.

     The layout	of the GPIO device is defined at securelevel 0,	i.e. typically
     during system boot, and cannot be changed later.  GPIO pins can be	con-
     figured and given a symbolic name and device drivers that use GPIO	pins
     can be attached to	the gpio device	at securelevel 0.  All other pins will
     not be accessible once the	runlevel has been raised.

     The following structures and constants are	defined	in the <sys/gpio.h>
     header file:

     GPIOINFO struct gpio_info
	   Returns information about the GPIO controller in the	gpio_info

	   struct gpio_info {
		   int gpio_npins;	   /* total number of pins available */

     GPIOPINREAD struct	gpio_pin_op
	   Returns the input pin value in the gpio_pin_op structure:

	   #define GPIOPINMAXNAME	   64

	   struct gpio_pin_op {
		   char	gp_name[GPIOPINMAXNAME];   /* pin name */
		   int gp_pin;			   /* pin number */
		   int gp_value;		   /* value */

	   The gp_name or gp_pin field must be set before calling.

     GPIOPINWRITE struct gpio_pin_op
	   Writes the output value to the pin.	The value set in the gp_value
	   field must be either	GPIO_PIN_LOW (logical 0) or GPIO_PIN_HIGH
	   (logical 1).	 On return, the	gp_value field contains	the old	pin

     GPIOPINTOGGLE struct gpio_pin_op
	   Toggles the pin output value, i.e. changes it to the	opposite.
	   gp_value field is ignored and on return contains the	old pin	state.

     GPIOPINSET	struct gpio_pin_set
	   Changes pin configuration flags with	the new	ones provided in the
	   gpio_pin_set	structure:

	   #define GPIOPINMAXNAME	   64

	   struct gpio_pin_set {
		   char	gp_name[GPIOPINMAXNAME];   /* pin name */
		   int gp_pin;			   /* pin number */
		   int gp_caps;			   /* pin capabilities (ro) */
		   int gp_flags;		   /* pin configuration	flags */
		   char	gp_name2[GPIOPINMAXNAME];  /* new name */

	   The gp_flags	field is a combination of the following	flags:

	   GPIO_PIN_INPUT      input direction
	   GPIO_PIN_OUTPUT     output direction
	   GPIO_PIN_INOUT      bi-directional
	   GPIO_PIN_OPENDRAIN  open-drain output
	   GPIO_PIN_PUSHPULL   push-pull output
	   GPIO_PIN_TRISTATE   output disabled
	   GPIO_PIN_PULLUP     internal	pull-up	enabled
	   GPIO_PIN_PULLDOWN   internal	pull-down enabled
	   GPIO_PIN_INVIN      invert input
	   GPIO_PIN_INVOUT     invert output

	   Note	that the GPIO controller may not support all of	these flags.
	   On return the gp_caps field contains	flags that are supported.  If
	   no flags are	specified, the pin configuration stays unchanged.

	   Only	GPIO pins that have been set using GPIOPINSET will be accessi-
	   ble at securelevels greater than 0.

     GPIOPINUNSET struct gpio_pin_set
	   Unset the specified pin, i.e. clear its name	and make it inaccessi-
	   ble at securelevels greater than 0.

     GPIOATTACH	struct gpio_attach
	   Attach the device described in the gpio_attach structure on this
	   gpio	device.

	   struct gpio_attach {
		   char	ga_dvname[16];	   /* device name */
		   int ga_offset;	   /* pin number */
		   u_int32_t ga_mask;	   /* binary mask */

     GPIODETACH	struct gpio_attach
	   Detach a device from	this gpio device that was previously attached
	   using the GPIOATTACH	ioctl(2).  The ga_offset and ga_mask fields of
	   the gpio_attach structure are ignored.

     /dev/gpiou	 GPIO device unit u file.

     ioctl(2), gpioctl(8)

     The gpio device first appeared in OpenBSD 3.6.

     The gpio driver was written by Alexander Yurchenko	<>.
     Runtime device attachment was added by Marc Balmer	<>.

     Event capabilities	are not	supported.

FreeBSD	13.0			 May 16, 2020			  FreeBSD 13.0


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