GPIOHANDLE_GET_LINE_VALUES_IOCTL

Warning

This ioctl is part of GPIO Character Device Userspace API (v1) and is obsoleted by GPIO_V2_LINE_GET_VALUES_IOCTL.

Name

GPIOHANDLE_GET_LINE_VALUES_IOCTL - Get the values of all requested lines.

Synopsis

GPIOHANDLE_GET_LINE_VALUES_IOCTL

int ioctl(int handle_fd, GPIOHANDLE_GET_LINE_VALUES_IOCTL, struct gpiohandle_data *values)

Arguments

handle_fd

The file descriptor of the GPIO character device, as returned in the request.fd by GPIO_GET_LINEHANDLE_IOCTL.

values

The line_values to be populated.

Description

Get the values of all requested lines.

The values returned are logical, indicating if the line is active or inactive. The GPIOHANDLE_REQUEST_ACTIVE_LOW flag controls the mapping between physical values (high/low) and logical values (active/inactive). If GPIOHANDLE_REQUEST_ACTIVE_LOW is not set then high is active and low is inactive. If GPIOHANDLE_REQUEST_ACTIVE_LOW is set then low is active and high is inactive.

The values of both input and output lines may be read.

For output lines, the value returned is driver and configuration dependent and may be either the output buffer (the last requested value set) or the input buffer (the actual level of the line), and depending on the hardware and configuration these may differ.

This ioctl can also be used to read the line value for line events, substituting the event_fd for the handle_fd. As there is only one line requested in that case, only the one value is returned in values.

Return Value

On success 0 and values populated with the values read.

On error -1 and the errno variable is set appropriately. Common error codes are described in GPIO Error Codes.