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SubjectRe: [PATCH 3/3] ARM: gic: add OF based initialization
On 09/20/2011 06:08 PM, Grant Likely wrote:
> On Tue, Sep 20, 2011 at 03:24:04PM -0500, Rob Herring wrote:
>> From: Rob Herring <rob.herring@calxeda.com>
>>
>> This adds ARM gic interrupt controller initialization using device tree
>> data.
>>
>> The initialization function is intended to be called by of_irq_init
>> function like this:
>>
>> const static struct of_device_id irq_match[] = {
>> { .compatible = "arm,cortex-a9-gic", .data = gic_of_init, },
>> {}
>> };
>>
>> static void __init init_irqs(void)
>> {
>> of_irq_init(irq_match);
>> }
>>
>> Signed-off-by: Rob Herring <rob.herring@calxeda.com>
>> ---
>> Documentation/devicetree/bindings/arm/gic.txt | 55 +++++++++++++++
>> arch/arm/common/gic.c | 89 +++++++++++++++++++++++-
>> arch/arm/include/asm/hardware/gic.h | 12 ++++
>> 3 files changed, 152 insertions(+), 4 deletions(-)
>> create mode 100644 Documentation/devicetree/bindings/arm/gic.txt
>>
>> diff --git a/Documentation/devicetree/bindings/arm/gic.txt b/Documentation/devicetree/bindings/arm/gic.txt
>> new file mode 100644
>> index 0000000..52916b4
>> --- /dev/null
>> +++ b/Documentation/devicetree/bindings/arm/gic.txt
>> @@ -0,0 +1,55 @@
>> +* ARM Generic Interrupt Controller
>> +
>> +ARM SMP cores are often associated with a GIC, providing per processor
>> +interrupts (PPI), shared processor interrupts (SPI) and software
>> +generated interrupts (SGI).
>> +
>> +Primary GIC is attached directly to the CPU and typically has PPIs and SGIs.
>> +Secondary GICs are cascaded into the upward interrupt controller and do not
>> +have PPIs or SGIs.
>> +
>> +Main node required properties:
>> +
>> +- compatible : should be one of:
>> + "arm,cortex-a9-gic"
>> + "arm,arm11mp-gic"
>> +- interrupt-controller : Identifies the node as an interrupt controller
>> +- #interrupt-cells : Specifies the number of cells needed to encode an
>> + interrupt source. The type shall be a <u32> and the value shall be 3.
>> +
>> + The 1st cell is the interrupt type; 0 for SPI interrupts, 1 for PPI
>> + interrupts.
>> +
>> + The 2nd cell contains the interrupt number for the interrupt type.
>> + SPI interrupts are in the range [0-987]. PPI interrupts are in the
>> + range [0-15].
>> +
>> + The 3rd cell is the flags, encoded as follows:
>> + bits[3:0] trigger type and level flags.
>> + 1 = low-to-high edge triggered
>> + 2 = high-to-low edge triggered
>> + 4 = active high level-sensitive
>> + 8 = active low level-sensitive
>> + bits[15:8] PPI interrupt cpu mask. Each bit corresponds to each of
>> + the 8 possible cpus attached to the GIC. A bit set to '1' indicated
>> + the interrupt is wired to that CPU. Only valid for PPI interrupts.
>> +
>> +- reg : Specifies base physical address(s) and size of the GIC registers. The
>> + first region is the GIC distributor register base and size. The 2nd region is
>> + the GIC cpu interface register base and size.
>> +
>> +Optional
>> +- interrupts : Interrupt source of the parent interrupt controller. Only
>> + present on secondary GICs.
>> +
>> +Example:
>> +
>> + intc: interrupt-controller@fff11000 {
>> + compatible = "arm,cortex-a9-gic";
>> + #interrupt-cells = <3>;
>> + #address-cells = <1>;
>> + interrupt-controller;
>> + reg = <0xfff11000 0x1000>,
>> + <0xfff10100 0x100>;
>> + };
>> +
>
> Ack on the binding.
>
>> diff --git a/arch/arm/common/gic.c b/arch/arm/common/gic.c
>> index 666b278..84e69a4 100644
>> --- a/arch/arm/common/gic.c
>> +++ b/arch/arm/common/gic.c
>> @@ -28,6 +28,10 @@
>> #include <linux/smp.h>
>> #include <linux/cpumask.h>
>> #include <linux/io.h>
>> +#include <linux/of.h>
>> +#include <linux/of_address.h>
>> +#include <linux/of_irq.h>
>> +#include <linux/irqdomain.h>
>>
>> #include <asm/irq.h>
>> #include <asm/mach/irq.h>
>> @@ -255,6 +259,15 @@ void __init gic_cascade_irq(unsigned int gic_nr, unsigned int irq)
>> irq_set_chained_handler(irq, gic_handle_cascade_irq);
>> }
>>
>> +static int gic_irq_count(void __iomem *dist_base)
>> +{
>> + int gic_irqs = readl_relaxed(dist_base + GIC_DIST_CTR) & 0x1f;
>> + gic_irqs = (gic_irqs + 1) * 32;
>> + if (gic_irqs > 1020)
>> + gic_irqs = 1020;
>> + return gic_irqs;
>> +}
>> +
>> static void __init gic_dist_init(struct gic_chip_data *gic,
>> unsigned int irq_start)
>> {
>> @@ -277,10 +290,7 @@ static void __init gic_dist_init(struct gic_chip_data *gic,
>> * Find out how many interrupts are supported.
>> * The GIC only supports up to 1020 interrupt sources.
>> */
>> - gic_irqs = readl_relaxed(base + GIC_DIST_CTR) & 0x1f;
>> - gic_irqs = (gic_irqs + 1) * 32;
>> - if (gic_irqs > 1020)
>> - gic_irqs = 1020;
>> + gic_irqs = gic_irq_count(base);
>>
>> /*
>> * Set all global interrupts to be level triggered, active low.
>> @@ -405,3 +415,74 @@ void gic_raise_softirq(const struct cpumask *mask, unsigned int irq)
>> writel_relaxed(map << 16 | irq, gic_data[0].dist_base + GIC_DIST_SOFTINT);
>> }
>> #endif
>> +
>> +#ifdef CONFIG_OF
>> +static int gic_cnt __initdata = 0;
>> +
>> +int gic_irq_domain_dt_translate(struct irq_domain *d,
>> + struct device_node *controller,
>> + const u32 *intspec, unsigned int intsize,
>> + unsigned long *out_hwirq, unsigned int *out_type)
>> +{
>> + struct gic_chip_data *gic_data = d->priv;
>> +
>> + if (d->of_node != controller)
>> + return -EINVAL;
>> + if (intsize < 3)
>> + return -EINVAL;
>> +
>> + *out_hwirq = intspec[1];
>> + /*
>> + * We've already skipped over SGIs, so PPIs need no translation.
>> + * For SPIs, we need to skip over 16 PPIs on primary GICs.
>> + */
>> + if (!intspec[0] && !gic_data->irq_offset)
>> + *out_hwirq += 16;
>
> I though that the offset was 32 to get from SPI number to Interrrupt
> ID? And that PPI interrupts start at Interrupt ID 16? Or am I
> mistaken about the hwirq number that this driver uses internally?
>

There's basically 2 cases to handle: primary and secondary controllers.

For primary ctrlrs, the domain irq_base is already 16 to skip over SGIs
and legacy ISA interrupts. So PPIs don't need any conversion and SPIs
only need 16 more added. I misspoke previously as it's not quite
independent of virq numbering because entry-macro-gic.S is still fixed
GIC ID = Linux virq (or offset of 32 in Exynos case).

For secondary ctrlrs, the gic code already accounts for 32 offset in ID
to Linux virq with the irq_offset field which is set to Linux virq base
- 32. So in this case, no conversion is needed.

I don't really see a better way without breaking non-DT use of the gic.

Rob


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