[uClinux-dev] External 16550 UART on a coldifre 5272 based board

Greg Ungerer gerg at snapgear.com
Thu Apr 4 08:06:03 EST 2002


Hi Subash,

Subash Kalbarga wrote:
> I have a coldfire based board(5272) but we have added an external UART 
> (16550) to the board.
>
> What would the best approach be for getting a serial driver attach to this
> 
> I know that the Internal UART of the coldfire differs significantly from 
> the standard 16550.
> 
> Should I
> 
> A)    change mcfserial.c to accommodate this new serial port
> 
> B)     Change serial.c (default linux driver)  to handle this serial 
> port? I saw some provisions for Memory mapped addressing of registers 
> etc in serial.c
> 
> If anyone who has done this before can point me in the right direction, 
> I will be thankful. Any problems I should specifically look for and any 
> pitfalls?

You should modify the serial.c driver. It is relatively easy to
convert for use on ColdFire hardware. The serial.c in the uClinux-2.0.x
tree (at ~/drivers/char/serial.c) already has ColdFire support in it.
Look for the CONFIG_COLDFIRE and CONFIG_NETtel defines in it.

Basically I modified the in/out functions to use memory mapped
addressing, and made some other small changes to allow for the slightly
different interrupt setup.

Regards
Greg


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