GPIO_V2_LINE_GET_VALUES_IOCTL

Name

GPIO_V2_LINE_GET_VALUES_IOCTL - Get the values of requested lines.

Synopsis

GPIO_V2_LINE_GET_VALUES_IOCTL

int ioctl(int req_fd, GPIO_V2_LINE_GET_VALUES_IOCTL, struct gpio_v2_line_values *values)

Arguments

req_fd

The file descriptor of the GPIO character device, as returned in the request.fd by GPIO_V2_GET_LINE_IOCTL.

values

The line_values to get with the mask set to indicate the subset of requested lines to get.

Description

Get the values of requested lines.

The values returned are logical, indicating if the line is active or inactive. The GPIO_V2_LINE_FLAG_ACTIVE_LOW flag controls the mapping between physical values (high/low) and logical values (active/inactive). If GPIO_V2_LINE_FLAG_ACTIVE_LOW is not set then high is active and low is inactive. If GPIO_V2_LINE_FLAG_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.

Return Value

On success 0 and the corresponding values.bits contain the value read.

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