[Linux-parport] using ppdev instead of direct hardware access

stef stef-listes at wanadoo.fr
Mon Jan 12 16:06:50 GMT 2004


        I'm in the process of adding ECP support for my parallel port
scanner, and I have trouble to see how to do it with ppdev. It uses such
sequences (addr are relative to parport address):

OUT +2, 4
OUT +1026,74   -> go to ECP FIFO mode
IN  +1026=75   ->read ECR
OUT +0, A
IN  +1026=75
IN  +1026=75
OUT +1026,34  -> go to byte mode
OUT +2,20
OUT +1026,74   -> go to ECP FIFO mode
IN  +1026=74
IN  +1024= 0
IN  +2=20
OUT +2, 4
OUT +1026,34      -> go to byte mode

      I am far from understanding how to set to ECP FIFO or plain
 ECP with the available ppdev ioctls. The ones I think I need are
marked obsoleted, and have no kernel code.

       Also, I have still to figure from/to which addr read/write go.

       Any hint is welcome.



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