It seems likely that at some point we will want a generic interrupt uclass.
But this is a big undertaking as it involves unifying code across multiple
architectures.
As a first step, create a simple IRQ uclass and a driver for x86. This can
be generalised later as required.
Adjust pirq_init() to probe this driver, which has the effect of creating
routing tables and setting up the interrupt routing. This is a start
towards making interrupts fit better with driver model.
Signed-off-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Bin Meng <bmeng.cn@gmail.com>
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