Re: [PATCH v5 1/2] of: Documentation: Specify local APIC ID in "reg"

From: Mark Rutland
Date: Tue Mar 13 2018 - 07:02:05 EST


On Mon, Mar 12, 2018 at 03:21:48PM -0700, Ivan Gorinov wrote:
> Set the "reg" property to the processor's local APIC ID.
> Local APIC ID is assigned by hardware and may differ from CPU number.
>
> Signed-off-by: Ivan Gorinov <ivan.gorinov@xxxxxxxxx>
> ---
> Documentation/devicetree/bindings/x86/ce4100.txt | 38 ++++++++++++++++++------
> 1 file changed, 29 insertions(+), 9 deletions(-)
>
> diff --git a/Documentation/devicetree/bindings/x86/ce4100.txt b/Documentation/devicetree/bindings/x86/ce4100.txt
> index b49ae59..5a4bd83 100644
> --- a/Documentation/devicetree/bindings/x86/ce4100.txt
> +++ b/Documentation/devicetree/bindings/x86/ce4100.txt
> @@ -7,17 +7,37 @@ Many of the "generic" devices like HPET or IO APIC have the ce4100
> name in their compatible property because they first appeared in this
> SoC.
>
> -The CPU node
> -------------
> - cpu@0 {
> - device_type = "cpu";
> - compatible = "intel,ce4100";
> - reg = <0>;
> - lapic = <&lapic0>;
> +The CPU nodes
> +-------------
> +
> + cpus {
> + #address-cells = <1>;
> + #size-cells = <0>;
> +
> + cpu@0 {
> + device_type = "cpu";
> + compatible = "intel,ce4100";
> + reg = <0x00>;
> + };
> +
> + cpu@1 {
> + device_type = "cpu";
> + compatible = "intel,ce4100";
> + reg = <0x02>;
> + };

The unit-address (the bit after the '@' in the node name) should match
the reg, so this node should be named cpu@2.

If there's another ID associated with each CPU, then this should be
described in another property.

> };
>
> -The reg property describes the CPU number. The lapic property points to
> -the local APIC timer.

Why was the lapic phandle removed?

Thanks,
Mark.

> +A "cpu" node describes one logical processor (hardware thread).
> +
> +Required properties:
> +
> +- device_type
> + Device type, must be "cpu".
> +
> +- reg
> + Local APIC ID, a unique number assigned to each processor by
> + hardware. This ID is used to specify the destination of interrupt
> + messages with "physical" destination mode, including startup IPI.
>
> The SoC node
> ------------
> --
> 2.7.4
>