Re: [PATCH 3/3] ARM: gic: add OF based initialization

[Grant Likely <grant.likely@secretlab.ca>]

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?

Otherwise, the change looks about right to me.

g.