e48fe75afa
Update description of reconfiguration rules, adding requirement that a direction flag be set or the configuration is considered invalid. Signed-off-by: Kent Gibson <warthog618@gmail.com> Link: https://lore.kernel.org/r/20240626052925.174272-4-warthog618@gmail.com Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
67 lines
1.8 KiB
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67 lines
1.8 KiB
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.. SPDX-License-Identifier: GPL-2.0
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.. _GPIOHANDLE_SET_CONFIG_IOCTL:
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***************************
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GPIOHANDLE_SET_CONFIG_IOCTL
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***************************
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.. warning::
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This ioctl is part of chardev_v1.rst and is obsoleted by
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gpio-v2-line-set-config-ioctl.rst.
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Name
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====
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GPIOHANDLE_SET_CONFIG_IOCTL - Update the configuration of previously requested lines.
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Synopsis
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========
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.. c:macro:: GPIOHANDLE_SET_CONFIG_IOCTL
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``int ioctl(int handle_fd, GPIOHANDLE_SET_CONFIG_IOCTL, struct gpiohandle_config *config)``
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Arguments
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=========
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``handle_fd``
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The file descriptor of the GPIO character device, as returned in the
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:c:type:`request.fd<gpiohandle_request>` by gpio-get-linehandle-ioctl.rst.
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``config``
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The new :c:type:`configuration<gpiohandle_config>` to apply to the
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requested lines.
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Description
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===========
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Update the configuration of previously requested lines, without releasing the
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line or introducing potential glitches.
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The configuration applies to all requested lines.
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The same :ref:`gpio-get-linehandle-config-rules` and
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:ref:`gpio-get-linehandle-config-support` that apply when requesting the
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lines also apply when updating the line configuration, with the additional
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restriction that a direction flag must be set. Requesting an invalid
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configuration, including without a direction flag set, is an error
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(**EINVAL**).
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The motivating use case for this command is changing direction of
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bi-directional lines between input and output, but it may be used more
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generally to move lines seamlessly from one configuration state to another.
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To only change the value of output lines, use
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gpio-handle-set-line-values-ioctl.rst.
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First added in 5.5.
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Return Value
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============
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On success 0.
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On error -1 and the ``errno`` variable is set appropriately.
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Common error codes are described in error-codes.rst.
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