1.\" $NetBSD: gpio.4,v 1.14 2009/08/23 15:41:28 wiz Exp $ 2.\" $OpenBSD: gpio.4,v 1.5 2004/11/23 09:39:29 reyk Exp $ 3.\" 4.\" Copyright (c) 2004 Alexander Yurchenko <grange@openbsd.org> 5.\" 6.\" Permission to use, copy, modify, and distribute this software for any 7.\" purpose with or without fee is hereby granted, provided that the above 8.\" copyright notice and this permission notice appear in all copies. 9.\" 10.\" THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES 11.\" WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF 12.\" MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR 13.\" ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES 14.\" WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN 15.\" ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF 16.\" OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. 17.\" 18.Dd August 23, 2009 19.Dt GPIO 4 20.Os 21.Sh NAME 22.Nm gpio 23.Nd General Purpose Input/Output 24.Sh SYNOPSIS 25.Cd "gpio* at elansc?" 26.Cd "gpio* at epgpio?" 27.Cd "gpio* at gcscpcib?" 28.Cd "gpio* at gpiosim?" 29.Cd "gpio* at gscpcib?" 30.Cd "gpio* at nsclpcsio?" 31.Cd "gpio* at ppbus?" 32.Pp 33.In sys/types.h 34.In sys/gpio.h 35.In sys/ioctl.h 36.Sh DESCRIPTION 37The 38.Nm 39device attaches to the 40.Tn GPIO 41controller and provides a uniform programming interface to its pins. 42.Pp 43Each 44.Tn GPIO 45controller with an attached 46.Nm 47device has an associated device file under the 48.Pa /dev 49directory, e.g.\& 50.Pa /dev/gpio0 . 51Access from userland is performed through 52.Xr ioctl 2 53calls on these devices. 54.Pp 55Whether the layout of the GPIO device can be configured is subject to 56authorization by the 57.Xr kauth 9 58framework. 59.Pp 60If for example 61.Xr secmodel_securelevel 9 62is active, the layout of the GPIO device is defined at a securelevel 63less than 1, i.e. typically during system boot, and cannot be changed later. 64GPIO pins can be configured and given a symbolic name and device drivers 65that use GPIO pins can be attached to the 66.Nm 67device at a securelevel less than 1. 68All other pins will not be accessible once the runlevel has been raised. 69.Sh IOCTL INTERFACE 70The following structures and constants are defined in the 71.Aq Pa sys/gpio.h 72header file: 73.Pp 74.Bl -tag -width XXXX -compact 75.It Dv GPIOINFO (struct gpio_info) 76Returns information about the 77.Tn GPIO 78controller in the 79.Fa gpio_info 80structure: 81.Bd -literal 82struct gpio_info { 83 int gpio_npins; /* total number of pins available */ 84}; 85.Ed 86.Pp 87.It Dv GPIOREAD (struct gpio_req) 88Returns the input pin value in the 89.Fa gpio_pin_op 90structure: 91.Bd -literal 92#define GPIOMAXNAME 64 93 94struct gpio_req { 95 char gp_name[GPIOMAXNAME]; /* pin name */ 96 int gp_pin; /* pin number */ 97 int gp_value; /* value */ 98}; 99.Ed 100.Pp 101The 102.Fa gp_name 103or 104.Fa gp_pin 105field must be set before calling. 106.Pp 107.It Dv GPIOWRITE (struct gpio_req) 108Writes the output value to the pin. 109The value set in the 110.Fa gp_value 111field must be either 112.Dv GPIO_PIN_LOW 113(logical 0) or 114.Dv GPIO_PIN_HIGH 115(logical 1). 116On return, the 117.Fa gp_value 118field contains the old pin state. 119.Pp 120.It Dv GPIOTOGGLE (struct gpio_req) 121Toggles the pin output value, i.e. changes it to the opposite. 122.Fa gp_value 123field is ignored and on return contains the old pin state. 124.Pp 125.It Dv GPIOSET (struct gpio_set) 126Changes pin configuration flags with the new ones provided in the 127.Fa gpio_set 128structure: 129.Bd -literal 130#define GPIOMAXNAME 64 131 132struct gpio_set { 133 char gp_name[GPIOMAXNAME]; /* pin name */ 134 int gp_pin; /* pin number */ 135 int gp_caps; /* pin capabilities (ro) */ 136 int gp_flags; /* pin configuration flags */ 137 char gp_name2[GPIOMAXNAME]; /* new name */ 138}; 139.Ed 140.Pp 141The 142.Fa gp_flags 143field is a combination of the following flags: 144.Pp 145.Bl -tag -width GPIO_PIN_OPENDRAIN -compact 146.It Dv GPIO_PIN_INPUT 147input direction 148.It Dv GPIO_PIN_OUTPUT 149output direction 150.It Dv GPIO_PIN_INOUT 151bi-directional 152.It Dv GPIO_PIN_OPENDRAIN 153open-drain output 154.It Dv GPIO_PIN_PUSHPULL 155push-pull output 156.It Dv GPIO_PIN_TRISTATE 157output disabled 158.It Dv GPIO_PIN_PULLUP 159internal pull-up enabled 160.It Dv GPIO_PIN_PULLDOWN 161internal pull-down enabled 162.It Dv GPIO_PIN_INVIN 163invert input 164.It Dv GPIO_PIN_INVOUT 165invert output 166.El 167.Pp 168Note that the GPIO controller 169may not support all of these flags. 170On return the 171.Fa gp_caps 172field contains flags that are supported. 173If no flags are specified, the pin configuration stays unchanged. 174.Pp 175Only GPIO pins that have been set using 176.Ar GPIOSET 177will be accessible at securelevels greater than 0. 178.Pp 179.It Dv GPIOUNSET (struct gpio_set) 180Unset the specified pin, i.e. clear its name and make it unaccessible 181at securelevels greater than 0. 182.Pp 183.It Dv GPIOATTACH (struct gpio_attach) 184Attach the device described in the 185.Fa gpio_attach 186structure on this gpio device. 187.Bd -literal 188struct gpio_attach { 189 char ga_dvname[16]; /* device name */ 190 int ga_offset; /* pin number */ 191 u_int32_t ga_mask; /* binary mask */ 192}; 193.Ed 194.Pp 195.It Dv GPIODETACH (struct gpio_attach) 196Detach a device from this gpio device that was previously attached using the 197.Dv GPIOATTACH 198.Xr ioctl 2 . 199The 200.Fa ga_offset 201and 202.Fa ga_mask 203fields of the 204.Fa gpio_attach 205structure are ignored. 206.El 207.Sh FILES 208.Bl -tag -width "/dev/gpiou" -compact 209.It /dev/gpio Ns Ar u 210GPIO device unit 211.Ar u 212file. 213.El 214.Sh SEE ALSO 215.Xr ioctl 2 , 216.Xr gpioctl 8 217.Sh HISTORY 218The 219.Nm 220device first appeared in 221.Ox 3.6 222and 223.Nx 4.0 . 224.Sh AUTHORS 225.An -nosplit 226The 227.Nm 228driver was written by 229.An Alexander Yurchenko Aq grange@openbsd.org . 230.Nm 231and was ported to 232.Nx 233by 234.An Jared D. McNeill Aq jmcneill@NetBSD.org . 235Runtime device attachment was added by 236.An Marc Balmer Aq marc@msys.ch . 237.Sh BUGS 238Event capabilities are not supported. 239