rs485.c

#include <sys/ioctl.h>
#include <linux/serial.h>
#include <stdbool.h>

int uart_get_rs485_config( int fd, struct serial_rs485 *config )
{
    return ioctl( fd, TIOCGRS485, config );
}

int uart_set_rs485_config( int fd, struct serial_rs485 const *config )
{
    return ioctl( fd, TIOCSRS485, config );
}

int uart_enable_rs485( int fd, bool active_low )
{
    struct serial_rs485 config;
    int res = uart_get_rs485_config( fd, &config );
    if( res < 0 )
        return res;
    if( active_low ) {
        config.flags &= ~SER_RS485_RTS_ON_SEND;
        config.flags |= SER_RS485_RTS_AFTER_SEND;
    } else {
        config.flags |= SER_RS485_RTS_ON_SEND;
        config.flags &= ~SER_RS485_RTS_AFTER_SEND;
    }
    config.flags |= SER_RS485_ENABLED;
    return uart_set_rs485_config( fd, &config );
}