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1.. SPDX-License-Identifier: GPL-2.02 3========================================4GPIO Character Device Userspace API (v1)5========================================6 7.. warning::8 This API is obsoleted by chardev.rst (v2).9 10 New developments should use the v2 API, and existing developments are11 encouraged to migrate as soon as possible, as this API will be removed12 in the future. The v2 API is a functional superset of the v1 API so any13 v1 call can be directly translated to a v2 equivalent.14 15 This interface will continue to be maintained for the migration period,16 but new features will only be added to the new API.17 18First added in 4.8.19 20The API is based around three major objects, the :ref:`gpio-v1-chip`, the21:ref:`gpio-v1-line-handle`, and the :ref:`gpio-v1-line-event`.22 23Where "line event" is used in this document it refers to the request that can24monitor a line for edge events, not the edge events themselves.25 26.. _gpio-v1-chip:27 28Chip29====30 31The Chip represents a single GPIO chip and is exposed to userspace using device32files of the form ``/dev/gpiochipX``.33 34Each chip supports a number of GPIO lines,35:c:type:`chip.lines<gpiochip_info>`. Lines on the chip are identified by an36``offset`` in the range from 0 to ``chip.lines - 1``, i.e. `[0,chip.lines)`.37 38Lines are requested from the chip using either gpio-get-linehandle-ioctl.rst39and the resulting line handle is used to access the GPIO chip's lines, or40gpio-get-lineevent-ioctl.rst and the resulting line event is used to monitor41a GPIO line for edge events.42 43Within this documentation, the file descriptor returned by calling `open()`44on the GPIO device file is referred to as ``chip_fd``.45 46Operations47----------48 49The following operations may be performed on the chip:50 51.. toctree::52 :titlesonly:53 54 Get Line Handle <gpio-get-linehandle-ioctl>55 Get Line Event <gpio-get-lineevent-ioctl>56 Get Chip Info <gpio-get-chipinfo-ioctl>57 Get Line Info <gpio-get-lineinfo-ioctl>58 Watch Line Info <gpio-get-lineinfo-watch-ioctl>59 Unwatch Line Info <gpio-get-lineinfo-unwatch-ioctl>60 Read Line Info Changed Events <gpio-lineinfo-changed-read>61 62.. _gpio-v1-line-handle:63 64Line Handle65===========66 67Line handles are created by gpio-get-linehandle-ioctl.rst and provide68access to a set of requested lines. The line handle is exposed to userspace69via the anonymous file descriptor returned in70:c:type:`request.fd<gpiohandle_request>` by gpio-get-linehandle-ioctl.rst.71 72Within this documentation, the line handle file descriptor is referred to73as ``handle_fd``.74 75Operations76----------77 78The following operations may be performed on the line handle:79 80.. toctree::81 :titlesonly:82 83 Get Line Values <gpio-handle-get-line-values-ioctl>84 Set Line Values <gpio-handle-set-line-values-ioctl>85 Reconfigure Lines <gpio-handle-set-config-ioctl>86 87.. _gpio-v1-line-event:88 89Line Event90==========91 92Line events are created by gpio-get-lineevent-ioctl.rst and provide93access to a requested line. The line event is exposed to userspace94via the anonymous file descriptor returned in95:c:type:`request.fd<gpioevent_request>` by gpio-get-lineevent-ioctl.rst.96 97Within this documentation, the line event file descriptor is referred to98as ``event_fd``.99 100Operations101----------102 103The following operations may be performed on the line event:104 105.. toctree::106 :titlesonly:107 108 Get Line Value <gpio-handle-get-line-values-ioctl>109 Read Line Edge Events <gpio-lineevent-data-read>110 111Types112=====113 114This section contains the structs that are referenced by the ABI v1.115 116The :c:type:`struct gpiochip_info<gpiochip_info>` is common to ABI v1 and v2.117 118.. kernel-doc:: include/uapi/linux/gpio.h119 :identifiers:120 gpioevent_data121 gpioevent_request122 gpiohandle_config123 gpiohandle_data124 gpiohandle_request125 gpioline_info126 gpioline_info_changed127 128.. toctree::129 :hidden:130 131 error-codes132