interrupt muxes, bus memory space and other fun amusing things

[Adrian Chadd]

On 5 January 2015 at 08:41, Warner Losh <imp at bsdimp.com> wrote:
>
>> So if I were Linux, I'd just implement a mux that pretends to trigger
>> interrupts in a much bigger IRQ space. Ie, they map IP0..IP7 to
>> irq0..7, then they pick another IRQ range for the AHB interrupts, and
>> another IRQ range for the IP2/IP3 interrupt mux. They have a
>> hard-coded mux that takes care of triggering the software IRQ based on
>> the hardware interrupt and mux register contents.
>>
>> So, how should I approach this?
>
> Same way. You’d create an interrupt device that registers an interrupt
> for the mux, then farms it out based on the contents of the registers.
> The MIPS interrupt handler might need some work (arm did) to
> allow this to happen, but it isn’t super difficult (though IIRc it is tedious).

Ok. So I can do that, but then devices hang off of which bus? nexus0?
Or this mux?

Can I create a mux bus to hang things off of that just pass all the
memory region requests up to the parent bus (nexus in this case) ?



-adrian