RE: [RFC PATCH v2 1/6] Documentation: DT: Add entry for CDX controller

From: "Gupta, Nipun" <Nipun.Gupta@amd.com>
To: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>,
	"robh+dt@kernel.org" <robh+dt@kernel.org>,
	"krzysztof.kozlowski+dt@linaro.org" 
	<krzysztof.kozlowski+dt@linaro.org>,
	"gregkh@linuxfoundation.org" <gregkh@linuxfoundation.org>,
	"rafael@kernel.org" <rafael@kernel.org>,
	"eric.auger@redhat.com" <eric.auger@redhat.com>,
	"alex.williamson@redhat.com" <alex.williamson@redhat.com>,
	"cohuck@redhat.com" <cohuck@redhat.com>,
	"Gupta, Puneet (DCG-ENG)" <puneet.gupta@amd.com>,
	"song.bao.hua@hisilicon.com" <song.bao.hua@hisilicon.com>,
	"mchehab+huawei@kernel.org" <mchehab+huawei@kernel.org>,
	"maz@kernel.org" <maz@kernel.org>,
	"f.fainelli@gmail.com" <f.fainelli@gmail.com>,
	"jeffrey.l.hugo@gmail.com" <jeffrey.l.hugo@gmail.com>,
	"saravanak@google.com" <saravanak@google.com>,
	"Michael.Srba@seznam.cz" <Michael.Srba@seznam.cz>,
	"mani@kernel.org" <mani@kernel.org>,
	"yishaih@nvidia.com" <yishaih@nvidia.com>,
	"jgg@ziepe.ca" <jgg@ziepe.ca>,
	"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
	"devicetree@vger.kernel.org" <devicetree@vger.kernel.org>,
	"kvm@vger.kernel.org" <kvm@vger.kernel.org>
Cc: "okaya@kernel.org" <okaya@kernel.org>,
	"Anand, Harpreet" <harpreet.anand@amd.com>,
	"Agarwal, Nikhil" <nikhil.agarwal@amd.com>,
	"Simek, Michal" <michal.simek@amd.com>,
	"git (AMD-Xilinx)" <git@amd.com>
Subject: RE: [RFC PATCH v2 1/6] Documentation: DT: Add entry for CDX controller
Date: Mon, 5 Sep 2022 14:05:35 +0000	[thread overview]
Message-ID: <DM6PR12MB308211F26296F3B816F3F005E87F9@DM6PR12MB3082.namprd12.prod.outlook.com> (raw)
In-Reply-To: <93f080cd-e586-112f-bac8-fa2a7f69efb3@linaro.org>

[AMD Official Use Only - General]

> -----Original Message-----
> From: Krzysztof Kozlowski <krzysztof.kozlowski@linaro.org>
> Sent: Thursday, August 18, 2022 3:24 PM
> To: Gupta, Nipun <Nipun.Gupta@amd.com>; robh+dt@kernel.org;
> krzysztof.kozlowski+dt@linaro.org; gregkh@linuxfoundation.org;
> rafael@kernel.org; eric.auger@redhat.com; alex.williamson@redhat.com;
> cohuck@redhat.com; Gupta, Puneet (DCG-ENG) <puneet.gupta@amd.com>;
> song.bao.hua@hisilicon.com; mchehab+huawei@kernel.org; maz@kernel.org;
> f.fainelli@gmail.com; jeffrey.l.hugo@gmail.com; saravanak@google.com;
> Michael.Srba@seznam.cz; mani@kernel.org; yishaih@nvidia.com;
> jgg@ziepe.ca; linux-kernel@vger.kernel.org; devicetree@vger.kernel.org;
> kvm@vger.kernel.org
> Cc: okaya@kernel.org; Anand, Harpreet <harpreet.anand@amd.com>; Agarwal,
> Nikhil <nikhil.agarwal@amd.com>; Simek, Michal <michal.simek@amd.com>;
> git (AMD-Xilinx) <git@amd.com>
> Subject: Re: [RFC PATCH v2 1/6] Documentation: DT: Add entry for CDX
> controller
> 
> [CAUTION: External Email]
> 
> On 17/08/2022 18:05, Nipun Gupta wrote:
> > This patch adds a devicetree binding documentation for CDX
> > controller.
> >
> Does not look like you tested the bindings. Please run `make
> dt_binding_check` (see
> Documentation/devicetree/bindings/writing-schema.rst for instructions).
> 

Thanks for the detailed review. Will fix the issues observed in v3.

> > CDX bus controller dynamically detects CDX bus and the
> > devices on these bus using CDX firmware.
> >
> > Signed-off-by: Nipun Gupta <mailto:nipun.gupta@amd.com>
> 
> Use subject perfixes matching the subsystem (git log --oneline -- ...).

Agree, will update.

> 
> > ---
> >  .../devicetree/bindings/bus/xlnx,cdx.yaml     | 108 ++++++++++++++++++
> >  MAINTAINERS                                   |   6 +
> >  2 files changed, 114 insertions(+)
> >  create mode 100644 Documentation/devicetree/bindings/bus/xlnx,cdx.yaml
> >
> > diff --git a/Documentation/devicetree/bindings/bus/xlnx,cdx.yaml
> b/Documentation/devicetree/bindings/bus/xlnx,cdx.yaml
> > new file mode 100644
> > index 000000000000..4247a1cff3c1
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/bus/xlnx,cdx.yaml
> > @@ -0,0 +1,108 @@
> > +# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
> > +%YAML 1.2
> > +---
> > +$id:
> https://nam11.safelinks.protection.outlook.com/?url=http%3A%2F%2Fdevicetree.org%2Fschemas%2Fmisc%2Fxlnx%2Ccdx.yaml%23&amp;data=05%7C01%7Cnipun.gupta%40amd.com%7C36ea349b1b464c0de27208da80ffa39e%7C3dd8961fe4884e608e11a82d994e183d%7C0%7C0%7C637964132708706641%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&amp;sdata=2cB6xGI3%2Brd%2BKXvvoZ7bDQvIAjIc7djKatDrJcuLJIg%3D&amp;reserved=0
> > +$schema:
> https://nam11.safelinks.protection.outlook.com/?url=http%3A%2F%2Fdevicetree.org%2Fmeta-schemas%2Fcore.yaml%23&amp;data=05%7C01%7Cnipun.gupta%40amd.com%7C36ea349b1b464c0de27208da80ffa39e%7C3dd8961fe4884e608e11a82d994e183d%7C0%7C0%7C637964132708706641%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&amp;sdata=DfEspCt84z77me2ShufHrL%2FK1X87p65XnbmVVr2xDrM%3D&amp;reserved=0
> > +
> > +title: Xilinx CDX bus controller
> > +
> > +description: |
> > +  CDX bus controller for Xilinx devices is implemented to
> 
> You need to describe what is this CDX bus. Google says nothing...

We will be adding more Arch related details in the cover letter patch to
describe the CDX bus.

> 
> > +  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 device. 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.
> > +
> > +  For generic IOMMU bindings, see:
> > +  Documentation/devicetree/bindings/iommu/iommu.txt.
> 
> Drop sentence.

Agree

> 
> > +
> > +  For arm-smmu binding, see:
> > +  Documentation/devicetree/bindings/iommu/arm,smmu.yaml.
> 
> Drop sentence.

Agree

> 
> > +
> > +  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.
> > +
> > +  For generic MSI bindings, see:
> > +  Documentation/devicetree/bindings/interrupt-controller/msi.txt.
> 
> Drop sentence.

Agree

> 
> > +
> > +  For GICv3 and GIC ITS bindings, see:
> > +  Documentation/devicetree/bindings/interrupt-controller/arm,gic-v3.yaml.
> 
> Drop sentence.

Agree

> 
> > +
> > +maintainers:
> > +  - Nipun Gupta <mailto:nipun.gupta@amd.com>
> > +  - Nikhil Agarwal <mailto:nikhil.agarwal@amd.com>
> > +
> > +properties:
> > +  compatible:
> > +    const: "xlnx,cdxbus-controller-1.0"
> 
> No quotes.

Agree. Will update in v3

> 
> > +
> > +  reg:
> > +    description: |
> > +      specifies the CDX firmware region shared memory accessible by the
> > +      ARM cores.
> 
> You need to describe the items instead (e.g. maxItems:1).

Will be updating in v3

> 
> > +
> > +  iommu-map:
> > +    description: |
> > +      Maps device Requestor ID to a stream ID and associated IOMMU. The
> > +      property is an arbitrary number of tuples of
> > +      (rid-base,iommu,streamid-base,length).
> > +
> > +      Any Requestor ID i in the interval [rid-base, rid-base + length) is
> > +      associated with the listed IOMMU, with the iommu-specifier
> > +      (i - streamid-base + streamid-base).
> 
> You need type and constraints.

Agree.

> 
> > +
> > +  msi-map:
> > +    description:
> > +      Maps an Requestor ID to a GIC ITS and associated msi-specifier
> > +      data (device ID). The property is an arbitrary number of tuples of
> > +      (rid-base,gic-its,deviceid-base,length).
> > +
> > +      Any Requestor ID in the interval [rid-base, rid-base + length) is
> > +      associated with the listed GIC ITS, with the msi-specifier
> > +      (i - rid-base + deviceid-base).
> 
> You need type and constraints.
> 
> 
> > +
> > +required:
> > +  - compatible
> > +  - reg
> > +  - iommu-map
> > +  - msi-map
> > +
> > +additionalProperties: false
> > +
> > +examples:
> > +  - |
> > +    smmu@ec000000 {
> > +        compatible = "arm,smmu-v3";
> > +        #iommu-cells = <1>;
> > +        ...
> 
> ???

Will be fixed in v3

> 
> > +
> > +    gic@e2000000 {
> > +        compatible = "arm,gic-v3";
> > +        interrupt-controller;
> > +        ...
> > +        its: gic-its@e2040000 {
> > +            compatible = "arm,gic-v3-its";
> > +            msi-controller;
> > +            ...
> > +        }
> > +    };
> > +
> > +    cdxbus: cdxbus@@4000000 {
> 
> Node names should be generic, so "cdx"

Would be using bus: cdxbus@4000000.
Kindly correct me if this does not seem to be correct.

Thanks,
Nipun

> 
> https://nam11.safelinks.protection.outlook.com/?url=https%3A%2F%2Fdevicetree-specification.readthedocs.io%2Fen%2Flatest%2Fchapter2-devicetree-basics.html%23generic-names-recommendation&amp;data=05%7C01%7Cnipun.gupta%40amd.com%7C36ea349b1b464c0de27208da80ffa39e%7C3dd8961fe4884e608e11a82d994e183d%7C0%7C0%7C637964132708706641%7CUnknown%7CTWFpbGZsb3d8eyJWIjoiMC4wLjAwMDAiLCJQIjoiV2luMzIiLCJBTiI6Ik1haWwiLCJXVCI6Mn0%3D%7C3000%7C%7C%7C&amp;sdata=QN8hk1CEOSmNSV5f0Z2uL4hatFrc1xYC5JBbptcCISA%3D&amp;reserved=0
> 
> Drop the label.
> 
> 
> > +        compatible = "xlnx,cdxbus-controller-1.0";
> > +        reg = <0x00000000 0x04000000 0 0x1000>;
> > +        /* define map for RIDs 250-259 */
> > +        iommu-map = <250 &smmu 250 10>;
> > +        /* define msi map for RIDs 250-259 */
> > +        msi-map = <250 &its 250 10>;
> > +    };
> Best regards,
> Krzysztof