UPGRADE YOUR BROWSER

We have detected your current browser version is not the latest one. Xilinx.com uses the latest web technologies to bring you the best online experience possible. Please upgrade to a Xilinx.com supported browser:Chrome, Firefox, Internet Explorer 11, Safari. Thank you!

cancel
Showing results for 
Search instead for 
Did you mean: 
Observer su.li@bd.com
Observer
217 Views
Registered: ‎10-18-2018

Add a UART, but TTY driver not working

Hi,

I tried to add a UART IP to my Zynq board. First I added an axi_uartlite IP and built FPGA and Linux image, but I couldn't see any TTY device created under /dev/ttyxx. Then I added an axi_uart16550 IP and rebuilt FPGA and Linux image. I saw 4 TTY devices were created. But I tested these 4 TTYs, only ttyS3 worked.  Please see the attached screen shot. Can any one help to explain this and guide how to create a UART device and tty driver. Thanks!

UartIssuejpg.jpg
0 Kudos
5 Replies
Moderator
Moderator
111 Views
Registered: ‎07-31-2012

Re: Add a UART, but TTY driver not working

Hi su.li@bd.com,

Make sure you enable axi uartlite driver in menu config to see ttyULx in the list.

Refer to https://xilinx-wiki.atlassian.net/wiki/spaces/A/pages/18842249/Uartlite+Driver

Regards

Praveen


-------------------------------------------------------------------------
Don’t forget to reply, kudo, and accept as solution.
-------------------------------------------------------------------------
Observer su.li@bd.com
Observer
86 Views
Registered: ‎10-18-2018

Re: Add a UART, but TTY driver not working

Thanks for reply! I will try this. Is the  CONFIG_SERIAL_UARTLITE variable already in some .config file? I couldn't find it.

# integrate into the kernel

CONFIG_SERIAL_UARTLITE=y

In addition, this potentially solves my first part of issues. My second part is why axi_uart16550 IP would create 4 device? Please see my design and question screen shot. 

 

 

AddTwoUartIssuejpg.jpg
0 Kudos
Moderator
Moderator
69 Views
Registered: ‎07-31-2012

Re: Add a UART, but TTY driver not working

Hi su.li@bd.com,

Try root@zcu102:~# dmesg |grep serial and see what result you are getting back.

Regards

Praveen

 


-------------------------------------------------------------------------
Don’t forget to reply, kudo, and accept as solution.
-------------------------------------------------------------------------
Xilinx Employee
Xilinx Employee
64 Views
Registered: ‎06-27-2017

Re: Add a UART, but TTY driver not working

su.li@bd.com,

To add more along with pvenugo, could you please check whether driver got probed as mentioned in wiki

 

[   16.039167] Serial: 8250/16550 driver, 4 ports, IRQ sharing disabled
[   16.230793] 800c0000.serial: ttyUL0 at MMIO 0x800c0000 (irq = 209, base_baud = 0) is a uartlite
[   16.485540] of_serial 800b0000.serial: FAILED to find out alias id
[   16.676807] 800b0000.serial: ttyS0 at MMIO 0x800b1000 (irq = 211, base_baud = 6250000) is a 16550A
Best Regards
Kranthi
--------------------------
Don't forget to reply, kudo, and accept as solution.
0 Kudos
Observer su.li@bd.com
Observer
23 Views
Registered: ‎10-18-2018

Re: Add a UART, but TTY driver not working

Thanks suggstions. You can see if I run ls /dev/tty*, I would see 4 devices. However, if run dmesg | grep serial, only one. 

UartDmesg.jpg
0 Kudos