RE: [PATCH 03/19] dt-bindings: bus: add CDX bus controller device tree bindings

[Gupta, Nipun]

[AMD Official Use Only - General]



> -----Original Message-----
> From: Krzysztof Kozlowski <krzysztof.kozlowski@xxxxxxxxxx>
> Sent: Tuesday, January 17, 2023 11:24 PM
> To: Gupta, Nipun <Nipun.Gupta@xxxxxxx>; robh+dt@xxxxxxxxxx;
> krzysztof.kozlowski+dt@xxxxxxxxxx; gregkh@xxxxxxxxxxxxxxxxxxx;
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> Cc: okaya@xxxxxxxxxx; Anand, Harpreet <harpreet.anand@xxxxxxx>; Agarwal,
> Nikhil <nikhil.agarwal@xxxxxxx>; Simek, Michal <michal.simek@xxxxxxx>;
> git (AMD-Xilinx) <git@xxxxxxx>
> Subject: Re: [PATCH 03/19] dt-bindings: bus: add CDX bus controller device tree
> bindings
> 
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> 
> 
> On 17/01/2023 14:41, Nipun Gupta wrote:
> > Add device tree bindings for CDX bus controller.
> 
> Subject: drop second/last, redundant "device tree bindings". The
> "dt-bindings" prefix is already stating that these are bindings.

Agree. Will update.

> 
> >
> > Signed-off-by: Nipun Gupta <nipun.gupta@xxxxxxx>
> > ---
> >  .../bindings/bus/xlnx,cdxbus-controller.yaml  | 68 +++++++++++++++++++
> >  MAINTAINERS                                   |  1 +
> >  2 files changed, 69 insertions(+)
> >  create mode 100644 Documentation/devicetree/bindings/bus/xlnx,cdxbus-
> controller.yaml
> >
> > diff --git a/Documentation/devicetree/bindings/bus/xlnx,cdxbus-
> controller.yaml b/Documentation/devicetree/bindings/bus/xlnx,cdxbus-
> controller.yaml
> > new file mode 100644
> > index 000000000000..b2f186864021
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/bus/xlnx,cdxbus-controller.yaml
> > @@ -0,0 +1,68 @@
> > +# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
> > +%YAML 1.2
> > +---
> > +$id: http://devicetree.org/schemas/bus/xlnx,cdxbus-controller.yaml#
> > +$schema: http://devicetree.org/meta-schemas/core.yaml#
> > +
> > +title: AMD CDX bus controller
> > +
> > +description: |
> > +  CDX bus controller for AMD devices is implemented to dynamically
> > +  detect CDX bus and devices on these bus using the firmware.
> > +  The CDX bus manages multiple FPGA based hardware devices, which
> > +  can support network, crypto or any other specialized type of
> > +  devices. These FPGA based devices can be added/modified dynamically
> > +  on run-time.
> > +
> > +  All devices on the CDX bus will have a unique streamid (for IOMMU)
> > +  and a unique device ID (for MSI) corresponding to a requestor ID
> > +  (one to one associated with the device). The streamid and deviceid
> > +  are used to configure SMMU and GIC-ITS respectively.
> > +
> > +  iommu-map property is used to define the set of stream ids
> > +  corresponding to each device and the associated IOMMU.
> > +
> > +  The MSI writes are accompanied by sideband data (Device ID).
> > +  The msi-map property is used to associate the devices with the
> > +  device ID as well as the associated ITS controller.
> > +
> > +  rproc property (xlnx,rproc) is used to identify the remote processor
> > +  with which APU (Application Processor Unit) interacts to find out
> > +  the bus and device configuration.
> > +
> > +maintainers:
> > +  - Nipun Gupta <nipun.gupta@xxxxxxx>
> > +  - Nikhil Agarwal <nikhil.agarwal@xxxxxxx>
> > +
> > +properties:
> > +  compatible:
> > +    const: xlnx,cdxbus-controller
> 
> This misses SoC specific compatible. Drop "bus" - redundant. I would
> also say - drop controller - do you see any other devices with such
> compatible naming? Use naming consistent with other devices in the
> kernel. Just open some controllers - SPI, I2C etc. and look there.

Makes sense. Will use "xlnx,cdx" in compatible.

> 
> > +
> > +  iommu-map: true
> 
> No mask?

Currently there is no use for iommu-map-mask as RID's are one to
one mapped stream ID's, so we have not added this optional property.

> 
> > +
> > +  msi-map: true
> > +
> > +  xlnx,rproc:
> > +    $ref: /schemas/types.yaml#/definitions/phandle
> > +    description:
> > +      phandle to the remoteproc_r5 rproc node using which APU interacts
> > +      with remote processor.
> > +
> > +required:
> > +  - compatible
> > +  - iommu-map
> > +  - msi-map
> > +  - xlnx,rproc
> > +
> > +additionalProperties: false
> > +
> > +examples:
> > +  - |
> > +    cdxbus-controller {
> 
> Node names should be generic, so just cdx.
> https://devicetree-specification.readthedocs.io/en/latest/chapter2-devicetree-
> basics.html#generic-names-recommendation

Sure. Will update to cdx.

Thanks,
Nipun

> 
> > +        compatible = "xlnx,cdxbus-controller";
> > +        /* define map for RIDs 250-259 */
> > +        iommu-map = <250 &smmu 250 10>;
> 
> Best regards,
> Krzysztof