> [designing a keyboard controller to work with Linux]
>
> >Whatever hardware you need, the best is really to use something that can
> >be atached to the so called pcmcia bus on the SA1100. You might need some
> >logic to decode the address and activate a chip-enable signal if you have
> >more than one port to address. A GPIO, preferably between 0 and 10, can
> >be used as interrupt line.
>
> 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 ?
Some drivers are able to share interrupts. However you might consider
using multiple GPIOs for each device IRQs if performance is critical.
Note that if you use GPIOs above 10, they will all trigger the IRQ 11 in
the CPU which requires all drivers to share IRQ 11, even if the GEDR show
them separately.
Nicolas Pitre
nico@cam.org
nico@visuaide.com
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