From e54def4ad8144ab15f826416e2e0f290ef1901b4 Mon Sep 17 00:00:00 2001 From: Daniel Baumann Date: Wed, 19 Jun 2024 23:00:30 +0200 Subject: Adding upstream version 6.9.2. Signed-off-by: Daniel Baumann --- .../gpio/gpio-get-lineinfo-watch-ioctl.rst | 74 ++++++++++++++++++++++ 1 file changed, 74 insertions(+) create mode 100644 Documentation/userspace-api/gpio/gpio-get-lineinfo-watch-ioctl.rst (limited to 'Documentation/userspace-api/gpio/gpio-get-lineinfo-watch-ioctl.rst') diff --git a/Documentation/userspace-api/gpio/gpio-get-lineinfo-watch-ioctl.rst b/Documentation/userspace-api/gpio/gpio-get-lineinfo-watch-ioctl.rst new file mode 100644 index 0000000000..f5c92b69a4 --- /dev/null +++ b/Documentation/userspace-api/gpio/gpio-get-lineinfo-watch-ioctl.rst @@ -0,0 +1,74 @@ +.. SPDX-License-Identifier: GPL-2.0 + +.. _GPIO_GET_LINEINFO_WATCH_IOCTL: + +***************************** +GPIO_GET_LINEINFO_WATCH_IOCTL +***************************** + +.. warning:: + This ioctl is part of chardev_v1.rst and is obsoleted by + gpio-v2-get-lineinfo-watch-ioctl.rst. + +Name +==== + +GPIO_GET_LINEINFO_WATCH_IOCTL - Enable watching a line for changes to its +request state and configuration information. + +Synopsis +======== + +.. c:macro:: GPIO_GET_LINEINFO_WATCH_IOCTL + +``int ioctl(int chip_fd, GPIO_GET_LINEINFO_WATCH_IOCTL, struct gpioline_info *info)`` + +Arguments +========= + +``chip_fd`` + The file descriptor of the GPIO character device returned by `open()`. + +``info`` + The :c:type:`line_info` struct to be populated, with + the ``offset`` set to indicate the line to watch + +Description +=========== + +Enable watching a line for changes to its request state and configuration +information. Changes to line info include a line being requested, released +or reconfigured. + +.. note:: + Watching line info is not generally required, and would typically only be + used by a system monitoring component. + + The line info does NOT include the line value. + + The line must be requested using gpio-get-linehandle-ioctl.rst or + gpio-get-lineevent-ioctl.rst to access its value, and the line event can + monitor a line for events using gpio-lineevent-data-read.rst. + +By default all lines are unwatched when the GPIO chip is opened. + +Multiple lines may be watched simultaneously by adding a watch for each. + +Once a watch is set, any changes to line info will generate events which can be +read from the ``chip_fd`` as described in +gpio-lineinfo-changed-read.rst. + +Adding a watch to a line that is already watched is an error (**EBUSY**). + +Watches are specific to the ``chip_fd`` and are independent of watches +on the same GPIO chip opened with a separate call to `open()`. + +First added in 5.7. + +Return Value +============ + +On success 0 and ``info`` is populated with the current line info. + +On error -1 and the ``errno`` variable is set appropriately. +Common error codes are described in error-codes.rst. -- cgit v1.2.3