gpio(4) [freebsd man page]
GPIO(4) BSD Kernel Interfaces Manual GPIO(4) NAME
gpiobus -- GPIO bus system SYNOPSIS
To compile these devices into your kernel and use the device hints, place the following lines in your kernel configuration file: device gpio device gpioc device gpioiic device gpioled Additional device entries for the ARM architecture include: device a10_gpio device bcm_gpio device imx51_gpio device lpcgpio device mv_gpio device ti_gpio device gpio_avila device gpio_cambria device zy7_gpio device pxagpio Additional device entries for the MIPS architecture include: device ar71xxx_gpio device octeon_gpio device rt305_gpio Additional device entries for the POWERPC architecture include: device wiigpio device macgpio DESCRIPTION
The gpiobus system provides a simple interface to the GPIO pins that are usually available on embedded architectures and can provide bit banging style devices to the system. The acronym GPIO means ``General-Purpose Input/Output.'' The BUS physically consists of multiple pins that can be configured for input/output, IRQ delivery, SDA/SCL iicbus use, etc. On some embedded architectures (like MIPS), discovery of the bus and configuration of the pins is done via device.hints(5) in the platform's kernel config(5) file. On some others (like ARM), where FDT(4) is used to describe the device tree, the bus discovery is done via the DTS passed to the kernel, being either statically compiled in, or by a variety of ways where the boot loader (or Open Firmware enabled system) passes the DTS blob to the kernel at boot. The following device.hints(5) are only provided by the ar71xx_gpio driver: hint.gpio.%d.pinmask This is a bitmask of pins on the GPIO board that we would like to expose for use to the host operating system. To expose pin 0, 4 and 7, use the bitmask of 10010001 converted to the hexadecimal value 0x0091. hint.gpio.%d.pinon This is a bitmask of pins on the GPIO board that will be set to ON at host start. To set pin 2, 5 and 13 to be set ON at boot, use the bitmask of 10000000010010 converted to the hexadecimal value 0x2012. hint.gpio.function_set hint.gpio.function_clear These are bitmasks of pins that will remap a pin to handle a specific function (USB, UART TX/RX, etc) in the Atheros function registers. This is mainly used to set/clear functions that we need when they are set up or not set up by uBoot. Simply put, each pin of the GPIO interface is connected to an input/output of some device in a system. SEE ALSO
gpioiic(4), gpioled(4), iicbus(4), gpioctl(8) HISTORY
The gpiobus manual page first appeared in FreeBSD 10.0. AUTHORS
This manual page was written by Sean Bruno <sbruno@FreeBSD.org>. BSD
November 5, 2013 BSD
Check Out this Related Man Page
GPIOCTL(8) BSD System Manager's Manual GPIOCTL(8) NAME
gpioctl -- control GPIO devices SYNOPSIS
gpioctl [-q] device attach device offset mask [flag] gpioctl [-q] device pin [0 | 1 | 2] gpioctl [-q] device pin [on | off | toggle] gpioctl [-q] device pin set [flags] [name] gpioctl [-q] device pin unset DESCRIPTION
The gpioctl program allows manipulation of GPIO (General Purpose Input/Output) device pins. Such devices can be either part of the chipset or embedded CPU, or a separate chip. The usual way of using GPIO is to connect some simple devices such as LEDs and 1-wire thermal sensors to its pins. Each GPIO device has an associated device file in the /dev directory. device can be specified with or without the /dev prefix. For example, /dev/gpio0 or gpio0. GPIO pins can be either ``read'' or ``written'' with the values of logical 0 or 1. If only a pin number is specified on the command line, the pin state will be read from the GPIO controller and displayed. To write to a pin, a value must be specified after the pin number. Val- ues can be either 0 or 1. A value of 2 ``toggles'' the pin, i.e. changes its state to the opposite. Instead of the numerical values, the word on, off, or toggle can be used. To Only pins that have been configured at securelevel 0, typically during system startup, are accessible once the securelevel has been raised. Pins can be given symbolic names for easier use. Besides using individual pins, device drivers that use GPIO pins can be attached to a gpio(4) device using the gpioctl command. Such drivers can be detached at runtime using the drvctl(8) command. The following configuration flags are supported by the GPIO framework: in input direction out output direction inout bi-directional od open-drain output pp push-pull output tri tri-state (output disabled) pu internal pull-up enabled pd internal pull-down enabled iin invert input iout invert output pulsate pulsate output at a hardware-defined frequency and duty cycle Note that not all the flags may be supported by the particular GPIO controller. When executed with only the gpio(4) device name as argument, gpioctl reads information about the GPIO device and displays it. At securelevel 0 the number of physically available pins is displayed, at higher securelevels the number of configured (set) pins is displayed. The options are as follows: -q Operate quietly i.e. nothing is printed to stdout. FILES
/dev/gpiou GPIO device unit u file. EXAMPLES
Configure pin 20 to have push-pull output: # gpioctl gpio0 20 set out pp Write logical 1 to pin 20: # gpioctl gpio0 20 1 Attach a onewire(4) bus on a gpioow(4) device on pin 4: # gpioctl gpio0 attach gpioow 4 0x01 Detach the gpioow0 device: # drvctl -d gpioow0 Configure pin 5 as output and name it error_led: # gpioctl gpio0 5 set out error_led Toggle the error_led: # gpioctl gpio0 error_led 2 SEE ALSO
gpio(4), drvctl(8) HISTORY
The gpioctl command first appeared in OpenBSD 3.6 and NetBSD 4.0. AUTHORS
The gpioctl program was written by Alexander Yurchenko <grange@openbsd.org>. Device attachment was added by Marc Balmer <marc@msys.ch>. BSD
November 13, 2011 BSD