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6a9c15083b
Update description of reconfiguration rules, adding requirement that a direction flag be set to enable changing configuration for a line. Signed-off-by: Kent Gibson <warthog618@gmail.com> Link: https://lore.kernel.org/r/20240626052925.174272-5-warthog618@gmail.com Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@linaro.org>
62 lines
1.8 KiB
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62 lines
1.8 KiB
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.. SPDX-License-Identifier: GPL-2.0
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.. _GPIO_V2_LINE_SET_CONFIG_IOCTL:
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*****************************
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GPIO_V2_LINE_SET_CONFIG_IOCTL
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*****************************
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Name
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====
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GPIO_V2_LINE_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:: GPIO_V2_LINE_SET_CONFIG_IOCTL
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``int ioctl(int req_fd, GPIO_V2_LINE_SET_CONFIG_IOCTL, struct gpio_v2_line_config *config)``
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Arguments
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=========
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``req_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<gpio_v2_line_request>` by gpio-v2-get-line-ioctl.rst.
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``config``
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The new :c:type:`configuration<gpio_v2_line_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 new configuration must specify a configuration for all requested lines.
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The same :ref:`gpio-v2-get-line-config-rules` and
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:ref:`gpio-v2-get-line-config-support` that apply when requesting the lines
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also apply when updating the line configuration, with the additional
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restriction that a direction flag must be set to enable reconfiguration.
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If no direction flag is set in the configuration for a given line then the
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configuration for that line is left unchanged.
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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 also be used to
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dynamically control edge detection, or more generally move lines seamlessly
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from one configuration state to another.
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To only change the value of output lines, use
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gpio-v2-line-set-values-ioctl.rst.
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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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