Messages in this thread | | | Date | Mon, 24 Nov 2014 22:57:50 +0800 | From | Jiang Liu <> | Subject | Re: [PATCH v3 06/13] irqchip: GICv3: ITS: LPI allocator |
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On 2014/11/24 22:35, Marc Zyngier wrote: > LPIs are the type of interrupts that are used by the ITS. Given > the size of the namespace (anywhere between 16 and 32bit), interrupt > IDs are allocated in chunks of 32. > > Signed-off-by: Marc Zyngier <marc.zyngier@arm.com> > --- > drivers/irqchip/irq-gic-v3-its.c | 103 +++++++++++++++++++++++++++++++++++++++ > 1 file changed, 103 insertions(+) > > diff --git a/drivers/irqchip/irq-gic-v3-its.c b/drivers/irqchip/irq-gic-v3-its.c > index d24bebd..4154a16 100644 > --- a/drivers/irqchip/irq-gic-v3-its.c > +++ b/drivers/irqchip/irq-gic-v3-its.c > @@ -586,3 +586,106 @@ static struct irq_chip its_irq_chip = { > .irq_eoi = its_eoi_irq, > .irq_set_affinity = its_set_affinity, > }; > + > +/* > + * How we allocate LPIs: > + * > + * The GIC has id_bits bits for interrupt identifiers. From there, we > + * must subtract 8192 which are reserved for SGIs/PPIs/SPIs. Then, as > + * we allocate LPIs by chunks of 32, we can shift the whole thing by 5 > + * bits to the right. Just curious, why 32? sizeof(long) is 4 on ARM64?
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