@brief Read current value from a single GPIO line.
@param device Name, path, number or label of the gpiochip.
@param offset Offset of the GPIO line.
@param active_low The active state of this line - true if low.
@param consumer Name of the consumer.
@param flags The flags for the line.
@return 0 or 1 (GPIO value) if the operation succeeds, -1 on error.
@brief Read current value from a single GPIO line. @param device Name, path, number or label of the gpiochip. @param offset Offset of the GPIO line. @param active_low The active state of this line - true if low. @param consumer Name of the consumer. @param flags The flags for the line. @return 0 or 1 (GPIO value) if the operation succeeds, -1 on error.