* 1. Standard baud rates are set in tty->termios->c_cflag
* 2. If these are not enough, you can set any speed using alt_speed as follows:
* - set tty->termios->c_cflag speed to B38400
* - set your real speed in tty->alt_speed; it gets ignored when
* alt_speed==0, (or)
* - call TIOCSSERIAL ioctl with (struct serial_struct) set as follows:
* flags & ASYNC_SPD_MASK == ASYNC_SPD_[HI, VHI, SHI, WARP], this just
* sets alt_speed to (HI: 57600, VHI: 115200, SHI: 230400, WARP: 460800)
* ** Steps 1, 2 are done courtesy of tty_get_baud_rate
* 3. You can also set baud rate by setting custom divisor as follows
* - set tty->termios->c_cflag speed to B38400
* - call TIOCSSERIAL ioctl with (struct serial_struct) set as follows:
* o flags & ASYNC_SPD_MASK == ASYNC_SPD_CUST
* o custom_divisor set to baud_base / your_new_baudrate