Messages in this thread | | | Date | Mon, 26 Sep 2011 22:11:27 +0100 | From | Jamie Iles <> | Subject | Re: [PATCH 3/3] ARM: gic: add OF based initialization |
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On Mon, Sep 26, 2011 at 03:49:11PM -0500, Rob Herring wrote: > On 09/26/2011 02:57 PM, Jamie Iles wrote: > > Hi Rob, > > > > On Tue, Sep 20, 2011 at 03:24:04PM -0500, Rob Herring wrote: > > [...] > >> +int __init gic_of_init(struct device_node *node, struct device_node *parent) > >> +{ > >> + void __iomem *cpu_base; > >> + void __iomem *dist_base; > >> + int irq; > >> + struct irq_domain *domain = &gic_data[gic_cnt].domain; > >> + > >> + if (WARN_ON(!node)) > >> + return -ENODEV; > >> + > >> + dist_base = of_iomap(node, 0); > >> + WARN(!dist_base, "unable to map gic dist registers\n"); > >> + > >> + cpu_base = of_iomap(node, 1); > >> + WARN(!cpu_base, "unable to map gic cpu registers\n"); > >> + > >> + domain->nr_irq = gic_irq_count(dist_base); > >> + /* subtract off SGIs. Also subtract off PPIs for secondary GICs */ > >> + if (parent) > >> + domain->nr_irq -= 32; > >> + else > >> + domain->nr_irq -= 16; > >> + > >> + domain->irq_base = irq_alloc_descs(-1, 16, domain->nr_irq, numa_node_id()); > > > > The way I understand irq_alloc_descs() (probably not very well) is that > > having the irq parameter < 0 and the from parameter 16 means that it > > needs to find domain->nr_irq descs starting from at least 16. But if > > the base is greater than 16, does this still work with the gic entry > > macros as they are? > > No, but that would only happen if a platform calls irq_alloc_descs prior > to this code. The root controller must be initialized first (for other > reasons as well). There are no calls to irq_alloc_descs in arch/arm. > > With the MULTI_IRQ GIC support Marc Z is working on, we could make the > GIC irq mapping be completely dynamic. Although, there's probably not > much reason to do so for the root controller.
OK, that makes sense. I think that if you were to do irq_alloc_descs(16, 16, domain->nr_irqs, num_node_id()) then that will guarantee the descriptors start from 16 (if they are available) which is probably nicer.
Jamie
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