1 .. SPDX-License-Identifier: GPL-2.0 2 3 .. _GPIOHANDLE_GET_LINE_VALUES_IOCTL: 4 5 ******************************** 6 GPIOHANDLE_GET_LINE_VALUES_IOCTL 7 ******************************** 8 .. warning:: 9 This ioctl is part of chardev_v1.rst and is obsoleted by 10 gpio-v2-line-get-values-ioctl.rst. 11 12 Name 13 ==== 14 15 GPIOHANDLE_GET_LINE_VALUES_IOCTL - Get the values of all requested lines. 16 17 Synopsis 18 ======== 19 20 .. c:macro:: GPIOHANDLE_GET_LINE_VALUES_IOCTL 21 22 ``int ioctl(int handle_fd, GPIOHANDLE_GET_LINE_VALUES_IOCTL, struct gpiohandle_data *values)`` 23 24 Arguments 25 ========= 26 27 ``handle_fd`` 28 The file descriptor of the GPIO character device, as returned in the 29 :c:type:`request.fd<gpiohandle_request>` by gpio-get-linehandle-ioctl.rst. 30 31 ``values`` 32 The :c:type:`line_values<gpiohandle_data>` to be populated. 33 34 Description 35 =========== 36 37 Get the values of all requested lines. 38 39 The values returned are logical, indicating if the line is active or inactive. 40 The ``GPIOHANDLE_REQUEST_ACTIVE_LOW`` flag controls the mapping between physical 41 values (high/low) and logical values (active/inactive). 42 If ``GPIOHANDLE_REQUEST_ACTIVE_LOW`` is not set then high is active and 43 low is inactive. If ``GPIOHANDLE_REQUEST_ACTIVE_LOW`` is set then low is active 44 and high is inactive. 45 46 The values of both input and output lines may be read. 47 48 For output lines, the value returned is driver and configuration dependent and 49 may be either the output buffer (the last requested value set) or the input 50 buffer (the actual level of the line), and depending on the hardware and 51 configuration these may differ. 52 53 This ioctl can also be used to read the line value for line events, 54 substituting the ``event_fd`` for the ``handle_fd``. As there is only 55 one line requested in that case, only the one value is returned in ``values``. 56 57 Return Value 58 ============ 59 60 On success 0 and ``values`` populated with the values read. 61 62 On error -1 and the ``errno`` variable is set appropriately. 63 Common error codes are described in error-codes.rst.
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