Re: [PATCH 1/2] ARM: gic: add irq_domain support
From: Grant Likely <hidden>
Date: 2011-09-29 20:16:24
Also in:
linux-arm-kernel, lkml
On Wed, Sep 28, 2011 at 10:53:55PM -0500, Rob Herring wrote:
From: Rob Herring <rob.herring-bsGFqQB8/DxBDgjK7y7TUQ@public.gmane.org> Convert the gic interrupt controller to use irq domains in preparation for device-tree binding and MULTI_IRQ. This allows for translation between GIC interrupt IDs and Linux irq numbers. The meaning of irq_offset has changed. It now is just the number of skipped GIC interrupt IDs for the controller. It will be 16 for primary GIC and 32 for secondary GICs.
[...]
quoted hunk ↗ jump to hunk
/*@@ -81,7 +82,7 @@ static inline unsigned int gic_irq(struct irq_data *d) */ static void gic_mask_irq(struct irq_data *d) { - u32 mask = 1 << (d->irq % 32); + u32 mask = 1 << (gic_irq(d) % 32);
This can probably change simply to d->hwirq if irq_offset is eliminated as I describe below.
void __init gic_init(unsigned int gic_nr, unsigned int irq_start,
void __iomem *dist_base, void __iomem *cpu_base)
{
struct gic_chip_data *gic;
+ struct irq_domain *domain;
+ int gic_irqs;
BUG_ON(gic_nr >= MAX_GIC_NR);
gic = &gic_data[gic_nr];
+ domain = &gic->domain;
gic->dist_base = dist_base;
gic->cpu_base = cpu_base;
- gic->irq_offset = (irq_start - 1) & ~31;
- if (gic_nr == 0)
+ /*
+ * For primary GICs, skip over SGIs.
+ * For secondary GICs, skip over PPIs, too.
+ */
+ if (gic_nr == 0) {
gic_cpu_base_addr = cpu_base;
+ gic->irq_offset = 16;
+ irq_start = (irq_start & ~31) + 16;With the switch to irq_domain, there should no longer be any need for a ~31 mask on the irq_start number. Yes, you'll want to make sure that it doesn't allocate below irq 16, but the driver should completely use the irq_domain to manage the mapping from linux-irq number to hwirq number. The ~31 mask appears to have been an optimization to quickly calculate hwirq number from the linux one, but that value is now found in irq_data->hwirq. irq_offset could almost be dropped entirely outside of probe because it no longer matters. Instead, populate the to_irq() hook so that the hwirq value gets set correctly from the outset. It would be better in general to have a consistent view of what the hwirq number means regardless of if it is a root GIC. g.