Application note for install legacy serial port under Linux

Cause of the legacy ttyS2~ttyS5 serial port cannot be auto install by Linux,
 please follow the below step to install the legacy serial port.

1. Check the serial port resource usage first.  Example into BIOS setup program to check your setting.
   Example:
   	Name	I/O	IRQ
   	====	====	====
	COM1	3F8	4
	COM2	2F8	3
	COM3	3E8	10
	COM4	2E8	10
	COM5	4F8	10
	COM6	4E8	10

2. You can check the resources used by the COM port with the "setserial" command, as follows:

	setserial /dev/ttySx, where x is 0 for COM1, 1 for COM2, 2 for COM3, 3 for COM4, etc.

3. If port resources is not curretly, use the setserial command to adjust it.
   Example your COM3~COM6 is not currently:
	setserial /dev/ttyS2 port 0x3e8 uart 16550a irq 10 baud_base 115200
	setserial /dev/ttyS3 port 0x2e8 uart 16550a irq 10 baud_base 115200
	setserial /dev/ttyS4 port 0x4f8 uart 16550a irq 10 baud_base 115200
	setserial /dev/ttyS5 port 0x4e8 uart 16550a irq 10 baud_base 115200

4. Add the setserial command into /etc/rc.local file.
	/bin/setserial /dev/ttyS2 port 0x3e8 uart 16550a irq 10 baud_base 115200
	/bin/setserial /dev/ttyS3 port 0x2e8 uart 16550a irq 10 baud_base 115200
	/bin/setserial /dev/ttyS4 port 0x4f8 uart 16550a irq 10 baud_base 115200
	/bin/setserial /dev/ttyS5 port 0x4e8 uart 16550a irq 10 baud_base 115200

5. Follow step 2 to double check the resource setting.

6. If the devices ttyS4 and ttyS5 does not exist, create them with MKNOD as below:

	mknod /dev/ttyS4 c 4 68
	chmod 660 /dev/ttyS4
	chgrp dialout /dev/ttyS4

	mknod /dev/ttyS5 c 4 69
	chmod 660 /dev/ttyS5
	chgrp dialout /dev/ttyS5
