1 .. SPDX-License-Identifier: GPL-2.0 2 3 .. _GPIO_V2_LINE_GET_VALUES_IOCTL: 4 5 ***************************** 6 GPIO_V2_LINE_GET_VALUES_IOCTL 7 ***************************** 8 9 Name 10 ==== 11 12 GPIO_V2_LINE_GET_VALUES_IOCTL - Get the values of requested lines. 13 14 Synopsis 15 ======== 16 17 .. c:macro:: GPIO_V2_LINE_GET_VALUES_IOCTL 18 19 ``int ioctl(int req_fd, GPIO_V2_LINE_GET_VALUES_IOCTL, struct gpio_v2_line_values *values)`` 20 21 Arguments 22 ========= 23 24 ``req_fd`` 25 The file descriptor of the GPIO character device, as returned in the 26 :c:type:`request.fd<gpio_v2_line_request>` by gpio-v2-get-line-ioctl.rst. 27 28 ``values`` 29 The :c:type:`line_values<gpio_v2_line_values>` to get with the ``mask`` set 30 to indicate the subset of requested lines to get. 31 32 Description 33 =========== 34 35 Get the values of requested lines. 36 37 The values returned are logical, indicating if the line is active or inactive. 38 The ``GPIO_V2_LINE_FLAG_ACTIVE_LOW`` flag controls the mapping between physical 39 values (high/low) and logical values (active/inactive). 40 If ``GPIO_V2_LINE_FLAG_ACTIVE_LOW`` is not set then high is active and low is 41 inactive. If ``GPIO_V2_LINE_FLAG_ACTIVE_LOW`` is set then low is active and 42 high is inactive. 43 44 The values of both input and output lines may be read. 45 46 For output lines, the value returned is driver and configuration dependent and 47 may be either the output buffer (the last requested value set) or the input 48 buffer (the actual level of the line), and depending on the hardware and 49 configuration these may differ. 50 51 Return Value 52 ============ 53 54 On success 0 and the corresponding :c:type:`values.bits<gpio_v2_line_values>` 55 contain the value read. 56 57 On error -1 and the ``errno`` variable is set appropriately. 58 Common error codes are described in error-codes.rst.
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