linux-kernel - Re: [PATCH 2/3] dt-bindings: arm: amlogic: Add SoC information bindings

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Message-ID: <4ab7d4ee-e805-69f1-b76b-b827b46285bd@baylibre.com>
Date:   Fri, 31 Mar 2017 16:10:30 +0200
From:   Neil Armstrong <narmstrong@...libre.com>
To:     Arnd Bergmann <arnd@...db.de>
Cc:     Kevin Hilman <khilman@...libre.com>, carlo@...one.org,
        linux-amlogic@...ts.infradead.org,
        Linux ARM <linux-arm-kernel@...ts.infradead.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        devicetree@...r.kernel.org
Subject: Re: [PATCH 2/3] dt-bindings: arm: amlogic: Add SoC information
 bindings

On 03/31/2017 03:44 PM, Arnd Bergmann wrote:
> On Fri, Mar 31, 2017 at 10:47 AM, Neil Armstrong
> <narmstrong@...libre.com> wrote:
>> Add bindings for the SoC information register of the Amlogic SoCs.
>>
>> Signed-off-by: Neil Armstrong <narmstrong@...libre.com>
>> ---
>>  Documentation/devicetree/bindings/arm/amlogic.txt | 20 ++++++++++++++++++++
>>  1 file changed, 20 insertions(+)
>>
>> diff --git a/Documentation/devicetree/bindings/arm/amlogic.txt b/Documentation/devicetree/bindings/arm/amlogic.txt
>> index bfd5b55..b850985 100644
>> --- a/Documentation/devicetree/bindings/arm/amlogic.txt
>> +++ b/Documentation/devicetree/bindings/arm/amlogic.txt
>> @@ -52,3 +52,23 @@ Board compatible values:
>>    - "amlogic,q201" (Meson gxm s912)
>>    - "nexbox,a95x" (Meson gxbb or Meson gxl s905x)
>>    - "nexbox,a1" (Meson gxm s912)
>> +
>> +Amlogic Meson GX SoCs Information
>> +----------------------------------
>> +
>> +The Meson SoCs have a Product Register that allows to retrieve SoC type,
>> +package and revision information. If present, a device node for this register
>> +should be added.
>> +
>> +Required properties:
>> +  - compatible: For Meson GX SoCs, must be "amlogic,meson-gx-socinfo".
>> +  - reg: Base address and length of the register block.
>> +
>> +Examples
>> +--------
>> +
>> +       chipid@220 {
>> +               compatible = "amlogic,meson-gx-socinfo";
>> +               reg = <0x0 0x00220 0x0 0x4>;
>> +       };
>> +
> 
> The register location would hint that this is in the middle of some block of
> random registers, i.e. a syscon or some unrelated device.
> 
> Are you sure that "socinfo" is the actual name of the IP block and that
> it only has a single 32-bit register?
> 
>      Arnd
> 

Hi Arnd,

I'm sorry I did not find any relevant registers in the docs or source code describing
it in a specific block of registers, and no close enough register definitions either.
They may be used by the secure firmware I imagine.

For the register name, Amlogic refers it to "cpu_version" in their code, but it really
gives some details on the whole SoC and package, and socinfo seems better.

Neil