UART AM335x with DMA

Amey Ghanekar

Prodigy 200 points

Hi,

I want to implement UART communication on AM335x with following characteristics.

1) Reception using DMA which generates interrupt after RX time-out.

2) Transmission using DMA to transfer given no. of bytes

I'm using Beaglebone black with following specification

uname -r = 4.1.13-g8dc6617

ti SDk = 02.00.01.07

Right now I have added uart1 node in dts file and found ttyO1 in /dev directory. But couldn't proceed further.

Can someone suggest a workaround for this?

Regards,

Amey

over 10 years ago

0 Biser Gatchev-XID over 10 years ago

TI__Guru**** 393215 points

I will ask the software team to look at this.

0 Yordan Kovachev over 10 years ago

TI__Guru**** 161600 points

Hi Amey,

Kernel 4.1.13 uses the 8250_omap.c driver as uart driver. And, as you can see from the kernel sources the 8250 driver uses both DMA & timeout interrupts. So could you please specify what exactly isn't working, since you say that you got the ttyO1 in /dev?

The links in the following wiki may be of use in your case:
processors.wiki.ti.com/.../Processor_SDK_Linux_UART

Best Regards,
Yordan

0 Amey Ghanekar over 10 years ago in reply to Yordan Kovachev

Prodigy 200 points

Hi Yordan,
Thanks for your reply.
I was going though 8250_omap.h but couldn't find the function to access particular UART. I'm planning to use UART1.
Any sample code related to loadable kernel module(wrapper) for uart is appreciated.

Best Regards,
Amey Ghanekar

0 Yordan Kovachev over 10 years ago in reply to Amey Ghanekar

TI__Guru**** 161600 points

Hi,

You can see the uart apis explained in Documentation/serial/tty.txt & Documentation/serial/driver.

A quick search gave me the following example codes, which I think are a good place to start:
www.tldp.org/.../x115.html
www.comptechdoc.org/.../linux_pgcserial.html
www.raviyp.com/.../189-serial-port-programming-in-linux-using-c-working-code

Hope this helps.

Best Regards,
Yordan

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UART AM335x with DMA