Re: [PATCH v4 1/2] bcma: register bcma as device tree driver

Arnd Bergmann
2014-09-22T07:26:51Z

On Monday 22 September 2014 00:38:27 Hauke Mehrtens wrote:
> +
> +- reg : iomem address range of chipcommon core
> +
> +The cores on the AXI bus are automatically detected by bcma with the
> +memory ranges they are using and they get registered afterwards.
> +Automatic detection of the IRQ number is not reliable on
> +BCM47xx/BCM53xx ARM SoCs. To assign IRQ numbers to the cores, provide
> +them manually through device tree. The IRQ number and the device tree
> +child entry will get assigned to the core with the matching reg address.
> +
> +Example:
> +
> + axi@18000000 {
> + compatible = "brcm,bus-axi";
> + reg = <0x18000000 0x1000>;
> + ranges = <0x00000000 0x18000000 0x00100000>;
> + #address-cells = <1>;
> + #size-cells = <1>;
> +
> + pcie@12000 {
> + reg = <0x00012000 0x1000>;
> + interrupts = <GIC_SPI 131 IRQ_TYPE_LEVEL_HIGH>;
> + };
> +
> + ethernet@24000 {
> + reg = <0x00024000 0x1000>;
> + interrupts = <GIC_SPI 147 IRQ_TYPE_LEVEL_HIGH>;
> + };
> +
> + ethernet@25000 {
> + reg = <0x00025000 0x1000>;
> + interrupts = <GIC_SPI 148 IRQ_TYPE_LEVEL_HIGH>;
> + };
> + };
>

While reading through this new version, I had a new idea about how
this could be handled better for any machines that have a unique
number in the interrupt field: If you do the same thing as PCI
and add an interrupt-map property [1], you can translate that
number into a real interrupt specifier for the child nodes.

This can work even if every device lists the local interrupt
as '0', since you can have device-specific lookup entries if you
use the correct interrupt-map-mask property.

Arnd

[1] http://www.openfirmware.org/1275/practice/imap/imap0_9d.pdf