[PATCH 1/3] irqchip: Move ARM GIC to drivers/irqchip

Russell King - ARM Linux linux at arm.linux.org.uk
Wed Oct 31 05:05:09 EDT 2012

On Tue, Oct 30, 2012 at 07:04:38PM -0500, Rob Herring wrote:
> On 10/30/2012 05:47 PM, Russell King - ARM Linux wrote:
> > On Tue, Oct 30, 2012 at 12:21:20PM -0500, Rob Herring wrote:
> >> Looking at this some more, arm64 doesn't need most of what's in gic.h.
> >> The register defines should be moved into the .c file. The remaining
> >> function declarations either are not needed (i.e. gic_init) or should
> >> should be done like the handle_irq function pointer init. We don't want
> >> to have platform code calling gic_cascade_irq or gic_raise_softirq
> >> directly.
> > 
> > Softirqs are about the SPIs which are used for SMP IPIs and platform
> > specific wakeup of CPUs.  And platform code _needs_ to specify the
> > way IPIs are delivered on the platform.  irqchip can't do that because
> > irqchip knows nothing about SPIs (neither does genirq.)
> Right. v7 is unchanged, so the question is really only about how v8 will
> do this. Hopefully, ARM is standardizing this for v8. We probably want
> the gic (or other irqchip) to setup a raise_softirq function ptr on init
> rather than having a direct call to gic_raise_softirq.

We already have that, except it's up to platforms to setup that pointer
via a function call into the SMP code - it's called set_smp_cross_call().
We could move that into the GIC code, as we don't have anyone with a GIC
which doesn't use gic_raise_softirq.

The only thing to remember is that there's non-SMP platforms with GICs.

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