Re: Designing a keyboard controller

Philip Blundell (pb@nexus.co.uk)
Tue, 14 Sep 1999 10:35:39 +0100

>That looks like a good solution. The question remains then: what does an
>8042 'look like', as seen from Linux ?

Just a set of data and status registers really. See drivers/char/pc_keyb.c,
or the RiscPC keyboard driver for another way of doing things (the Acorn
hardware provides its own PS/2 interface).

>A semi-related question: is it possible for multiple different devices on
>an ISA-ish bus to share an interrupt *on the processor side* ? For example,
>say I have a custom PIC which multiplexes (logic OR) the interrupt output
>of a keyboard controller with the interrupt output of an IDE controller
>onto one interrupt line for the processor. Does this work, or do I break
>any hidden assumptions in either the keyboard or the IDE driver ?

That should be fine. The IDE driver can already share interrupts; not sure
about the keyboard driver but it could be taught to do so easily enough.

p.

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