User`s guide

Registering a New UART Driver
i.MX53 System Development User’s Guide, Rev. 1
14-2 Freescale Semiconductor
14.2 Enabling UART on Kernel Menuconfig
Enable the UART driver on Linux menuconfig. This option is located at:
-> Device Drivers
-> Character devices
-> Serial drivers
<*> MXC Internal serial port support
[*] Support for console on a MXC/MX27/MX21 Internal serial port
After enabling the UART driver, build the Linux kernel and boot the board.
14.3 Testing the UART
By default, the UART is configured as follows:
• Baud Rate: 9600
• Data bits: 8
• Parity: None
• Stop bits: 1
• Flow Control: None
If the user used a different UART configuration for a device that needs to connect to the i.MX53 processor,
connection and communication will fail. There is a simple way to test whether the UART is properly
configured and enabled.
On the i.MX53 Linux command line, type the following:
echo “test” > /dev/ttymxc2
UART3 (J2 on the i.MX53 expansion board) sends the string “test”.
14.4 File Names and Locations
There are three Linux source code directories that contain relevant UART files.
Table 14-1 lists the UART files that are available on the directory <linux source code
directory>/drivers/serial/
Table 14-1. Available Files—First Set
File Description
mxc_uart.c Low level driver
serial_core.c Core driver that is included as part of standard Linux
mxc_uart_reg.h Register values
mxc_uart_early.c Source file to support early serial console for UART