8xx UART TX > 8 data bits

Robin Gilks robin.gilks at tait.co.nz
Wed Apr 13 09:17:18 EST 2005


I'm trying to get an SMC channel to operate as a UART with more than 8 
data bits (13 in fact!!). Using a 2.4.22 kernel on a mpc859 (basic 866).

This means its going to be getting two half words from the BDs for each 
'character'. With the constraints of the SMC requiring even addresses 
etc for this mode of operation, does anyone know if it will work writing 
2x8 bit characters at a time so as to keep the existing tty structure 
for SMC handling?

I've tried tracing the tty layers by code inspection but I keep getting 
lost in the indirections!! If I could find how the BDs are allocated as 
a result of a character write, then perhaps I could make minor mods to 
ensure memory allocs on an even address.

Could be that I'm totally off the wall but I'm trying for a 'minimum 
effort' viability hack :-))

Robin Gilks
Senior Design Engineer          Phone: (+64)(3) 357 1569
Tait Electronics                Fax  :  (+64)(3) 359 4632
PO Box 1645 Christchurch        Email : robin.gilks at tait.co.nz
New Zealand

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