57 lines
1.6 KiB
ReStructuredText
57 lines
1.6 KiB
ReStructuredText
.. SPDX-License-Identifier: GPL-2.0
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.. _GPIOHANDLE_GET_LINE_VALUES_IOCTL:
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********************************
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GPIOHANDLE_GET_LINE_VALUES_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-get-values-ioctl.rst.
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Name
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====
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GPIOHANDLE_GET_LINE_VALUES_IOCTL - Get the values of all requested lines.
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Synopsis
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========
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.. c:macro:: GPIOHANDLE_GET_LINE_VALUES_IOCTL
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``int ioctl(int handle_fd, GPIOHANDLE_GET_LINE_VALUES_IOCTL, struct gpiohandle_data *values)``
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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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``values``
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The :c:type:`line_values<gpiohandle_data>` to be populated.
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Description
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===========
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Get the values of all requested lines.
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The values of both input and output lines may be read.
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For output lines, the value returned is driver and configuration dependent and
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may be either the output buffer (the last requested value set) or the input
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buffer (the actual level of the line), and depending on the hardware and
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configuration these may differ.
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This ioctl can also be used to read the line value for line events,
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substituting the ``event_fd`` for the ``handle_fd``. As there is only
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one line requested in that case, only the one value is returned in ``values``.
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Return Value
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============
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On success 0 and ``values`` populated with the values read.
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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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