[PATCH v5 1/2] dt-bindings: mfd: syscon: Add ti,j721e-acspcie-proxy-ctrl compatible

[Andrew Davis]

On 1/10/25 9:35 AM, Rob Herring wrote:
> On Fri, Jan 10, 2025 at 11:03:30AM +0100, Romain Naour wrote:
>> From: Romain Naour <romain.naour at skf.com>
>>
>> The ACSPCIE_PROXY_CTRL registers within the CTRL_MMR space of TI's J721e
>> SoC are used to drive the reference clock to the PCIe Endpoint device via
>> the PAD IO Buffers. Add the compatible for allowing the PCIe driver to
>> obtain the regmap for the ACSPCIE_CTRL register within the System
>> Controller device-tree node in order to enable the PAD IO Buffers.
>>
>> Using the ti,j721e-acspcie-proxy-ctrl compatible imply to use "Proxy1"
>> address (1A090h) instead of "Proxy0" (18090h) to access
>> CTRLMMR_ACSPCIE0_CTRL register:
>>
>>    CTRLMMR_ACSPCIE0_CTRL Register (Proxy0 Offset = 18090h; Proxy1 Offset = 1A090h)
>>
>> "Proxy0" is used as the default access path that can be locked with the
>> help of "CTRLMMR_LOCK0_KICK0" and "CTRLMMR_LOCK0_KICK1" registers.
>>
>> The Technical Reference Manual for J721e SoC with details of the
>> ASCPCIE_CTRL registers is available at:
>> https://www.ti.com/lit/zip/spruil1
>>
>> Signed-off-by: Romain Naour <romain.naour at skf.com>
>> ---
>> v5:
>>    - Add missing change to the J721e system controller binding
>>      to avoid DT check warning when the new acspcie0_proxy_ctrl (syscon)
>>      will be added to J721e system controller node (Andrew Davis).
>>
>>    https://lore.kernel.org/linux-devicetree/90f47fae-a493-471d-8fe6-e7df741161be@ti.com/
>>
>>    - Explain why "Proxy1" address (1A090h) should be used while using
>>      ti,j721e-acspcie-proxy-ctrl compatible (Siddharth Vadapalli).
>>
>>    https://lore.kernel.org/linux-devicetree/begojbvvrpyjfr3pye7mqwiw73ucw5ynepdfujssr4jx4vs33a@pwahnph3qesl/
>>
>> v4: Add missing change in the second list (From Andrew Davis) [1]
>>    Rebase after the ti,j784s4-acspcie-proxy-ctrl compatible fix [2]
>>    [1] https://lore.kernel.org/linux-devicetree/20250103174524.28768-1-afd@ti.com/
>>    [2] https://lore.kernel.org/linux-devicetree/20250103174524.28768-2-afd@ti.com/
>>
>> v3: new commit
>> ---
>>   Documentation/devicetree/bindings/mfd/syscon.yaml           | 2 ++
>>   .../bindings/soc/ti/ti,j721e-system-controller.yaml         | 6 ++++++
>>   2 files changed, 8 insertions(+)
>>
>> diff --git a/Documentation/devicetree/bindings/mfd/syscon.yaml b/Documentation/devicetree/bindings/mfd/syscon.yaml
>> index 0e68c69e7bc9..1f3e67f432e7 100644
>> --- a/Documentation/devicetree/bindings/mfd/syscon.yaml
>> +++ b/Documentation/devicetree/bindings/mfd/syscon.yaml
>> @@ -115,6 +115,7 @@ select:
>>             - ti,am625-dss-oldi-io-ctrl
>>             - ti,am62p-cpsw-mac-efuse
>>             - ti,am654-dss-oldi-io-ctrl
>> +          - ti,j721e-acspcie-proxy-ctrl
>>             - ti,j784s4-acspcie-proxy-ctrl
>>             - ti,j784s4-pcie-ctrl
>>             - ti,keystone-pllctrl
>> @@ -213,6 +214,7 @@ properties:
>>             - ti,am625-dss-oldi-io-ctrl
>>             - ti,am62p-cpsw-mac-efuse
>>             - ti,am654-dss-oldi-io-ctrl
> 
>> +          - ti,j721e-acspcie-proxy-ctrl
>>             - ti,j784s4-acspcie-proxy-ctrl
> 
> How do these 2 compare? Are they compatible?
> 

Yes, they are 100% identical and compatible, but we were told
to make a new string anyway.. [0]

[0] https://lore.kernel.org/all/1bfdf1f1-7542-4149-a85d-2ac4b659b26b@kernel.org/


>>             - ti,j784s4-pcie-ctrl
>>             - ti,keystone-pllctrl
>> diff --git a/Documentation/devicetree/bindings/soc/ti/ti,j721e-system-controller.yaml b/Documentation/devicetree/bindings/soc/ti/ti,j721e-system-controller.yaml
>> index 378e9cc5fac2..16929218d611 100644
>> --- a/Documentation/devicetree/bindings/soc/ti/ti,j721e-system-controller.yaml
>> +++ b/Documentation/devicetree/bindings/soc/ti/ti,j721e-system-controller.yaml
>> @@ -68,6 +68,12 @@ patternProperties:
>>       description:
>>         The node corresponding to SoC chip identification.
>>   
>> +  "^syscon@[0-9a-f]+$":
>> +    type: object
>> +    $ref: /schemas/mfd/syscon.yaml#
>> +    description:
>> +      This is the ASPCIe control region.
> 
> So this is a syscon child of a syscon. The primary reason for 'syscon'
> compatible is to create a regmap. Why can't you use the parent's syscon?
> 

The parent node will not be a syscon soon. We made this whole bus a "syscon"
so we could just poke any register we wanted which was a hacky solution we
want to fix. The parent will be converted into a normal "simple-bus".

Most of the IP in this region can be described using normal DT devices,
but there are still just a couple registers like this where we need a raw
syscon (or we could make a proper device driver for these registers, but
that might be excessive, instead seems easy enough to just poke them
directly from the PCIe driver).

Andrew

> Rob