RE: [EXT] Re: [PATCH v3 2/5] dt-bindings: arm: fsl: add imx-se-fw binding doc

Pankaj Gupta
2024-06-18T10:58:51Z

> -----Original Message-----
> From: Conor Dooley <conor@kernel.org>
> Sent: Monday, June 17, 2024 10:07 PM
> To: Pankaj Gupta <pankaj.gupta@nxp.com>
> Cc: Jonathan Corbet <corbet@lwn.net>; Rob Herring <robh@kernel.org>;
> Krzysztof Kozlowski <krzk+dt@kernel.org>; Conor Dooley
> <conor+dt@kernel.org>; Shawn Guo <shawnguo@kernel.org>; Sascha Hauer
> <s.hauer@pengutronix.de>; Pengutronix Kernel Team
> <kernel@pengutronix.de>; Fabio Estevam <festevam@gmail.com>; Rob
> Herring <robh+dt@kernel.org>; Krzysztof Kozlowski
> <krzysztof.kozlowski+dt@linaro.org>; linux-doc@vger.kernel.org; linux-
> kernel@vger.kernel.org; devicetree@vger.kernel.org; imx@lists.linux.dev;
> linux-arm-kernel@lists.infradead.org
> Subject: [EXT] Re: [PATCH v3 2/5] dt-bindings: arm: fsl: add imx-se-fw binding
> doc
>
> On Mon, Jun 17, 2024 at 12:59:40PM +0530, Pankaj Gupta wrote:
> > The NXP security hardware IP(s) like: i.MX EdgeLock Enclave, V2X etc.,
> > creates an embedded secure enclave within the SoC boundary to enable
> > features like:
> > - HSM
> > - SHE
> > - V2X
> >
> > Secure-Enclave(s) communication interface are typically via message
> > unit, i.e., based on mailbox linux kernel driver. This driver enables
> > communication ensuring well defined message sequence protocol between
> > Application Core and enclave's firmware.
> >
> > Driver configures multiple misc-device on the MU, for multiple
> > user-space applications, to be able to communicate over single MU.
> >
> > It exists on some i.MX processors. e.g. i.MX8ULP, i.MX93 etc.
> >
> > Signed-off-by: Pankaj Gupta <pankaj.gupta@nxp.com>
> > ---
> > .../devicetree/bindings/firmware/fsl,imx-se.yaml | 160
> +++++++++++++++++++++
> > 1 file changed, 160 insertions(+)
> >
> > diff --git
> > a/Documentation/devicetree/bindings/firmware/fsl,imx-se.yaml
> > b/Documentation/devicetree/bindings/firmware/fsl,imx-se.yaml
> > new file mode 100644
> > index 000000000000..60ad1c4a3dfa
> > --- /dev/null
> > +++ b/Documentation/devicetree/bindings/firmware/fsl,imx-se.yaml
> > @@ -0,0 +1,160 @@
> > +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause) %YAML 1.2
> > +---
> > +$id: http://devicetree.org/schemas/firmware/fsl,imx-se.yaml#
> > +$schema: http://devicetree.org/meta-schemas/core.yaml#
> > +
> > +title: NXP i.MX HW Secure Enclave(s) EdgeLock Enclave
> > +
> > +maintainers:
> > + - Pankaj Gupta <pankaj.gupta@nxp.com>
> > +
> > +description: |
> > + NXP's SoC may contain one or multiple embedded secure-enclave HW
> > + IP(s) like i.MX EdgeLock Enclave, V2X etc. These NXP's HW IP(s)
> > + enables features like
> > + - Hardware Security Module (HSM),
> > + - Security Hardware Extension (SHE), and
> > + - Vehicular to Anything (V2X)
> > +
> > + Communication interface to the secure-enclaves is based on the
> > + messaging unit(s).
> > +
> > +properties:
> > + $nodename:
> > + pattern: "^[0-9a-z]*-if@[0-9a-f]+$"
>
> Just "firmware@<hex>" please.
>

Modified as per your suggestion,
- pattern: "^[0-9a-z]*-if@[0-9a-f]+$"
+ pattern: "^[0-9a-z]*-if@<hex>"

encountering the following error:
/home/yuktilab/linux_bkp/Documentation/devicetree/bindings/firmware/fsl,imx-se.example.dtb: ele-if@0: $nodename:0: 'ele-if@0' does not match '^[0-9a-z]*-if@<hex>'
from schema $id: http://devicetree.org/schemas/firmware/fsl,imx-se.yaml#
/home/yuktilab/linux_bkp/Documentation/devicetree/bindings/firmware/fsl,imx-se.example.dtb: v2x-if@3: $nodename:0: 'v2x-if@3' does not match '^[0-9a-z]*-if@<hex>'
from schema $id: http://devicetree.org/schemas/firmware/fsl,imx-se.yaml#
/home/yuktilab/linux_bkp/Documentation/devicetree/bindings/firmware/fsl,imx-se.example.dtb: v2x-if@4: $nodename:0: 'v2x-if@4' does not match '^[0-9a-z]*-if@<hex>'
from schema $id: http://devicetree.org/schemas/firmware/fsl,imx-se.yaml#
/home/yuktilab/linux_bkp/Documentation/devicetree/bindings/firmware/fsl,imx-se.example.dtb: v2x-if@5: $nodename:0: 'v2x-if@5' does not match '^[0-9a-z]*-if@<hex>'
from schema $id: http://devicetree.org/schemas/firmware/fsl,imx-se.yaml#

Please help and guide to resolve this comment, correctly.
Highly appreciated. Thanks.

> > +
> > + compatible:
> > + enum:
> > + - fsl,imx8ulp-se
> > + - fsl,imx93-se
> > + - fsl,imx95-se
> > +
> > + reg:
> > + maxItems: 1
> > + description: Identifier of the communication interface to secure-enclave.
> > +
> > + mboxes:
> > + description: contain a list of phandles to mailboxes.
> > + items:
> > + - description: Specify the mailbox used to send message to se firmware
> > + - description: Specify the mailbox used to receive message from
> > + se firmware
> > +
> > + mbox-names:
> > + items:
> > + - const: tx
> > + - const: rx
> > + - const: txdb
> > + - const: rxdb
> > + minItems: 2
> > +
> > + memory-region:
> > + description: contains a list of phandles to reserved external memory.
> > + items:
> > + - description: It is used by secure-enclave firmware. It is an optional
> > + property based on compatible and identifier to communication
> interface.
> > + (see bindings/reserved-memory/reserved-memory.txt)
> > +
> > + sram:
> > + description: contains a list of phandles to sram.
>
> There's only 1 phandle allowed, don't describe it as a list.
> Same for memory-region.

Accepted. Will do the following changes.
memory-region:
- description: contains a list of phandles to reserved external memory.
+ description: contains the phandle to reserved external memory.

sram:
- description: contains a list of phandles to sram.
- $ref: /schemas/types.yaml#/definitions/phandle-array
+ description: contains the phandle to sram.
items:
>
> > + $ref: /schemas/types.yaml#/definitions/phandle-array
> > + items:
> > + - description: Phandle to the device SRAM. It is an optional property
> > + based on compatible and identifier to communication interface.
> > +
> > +allOf:
> > + # memory-region
> > + - if:
> > + properties:
> > + compatible:
> > + contains:
> > + enum:
> > + - fsl,imx8ulp-se
> > + - fsl,imx93-se
> > + then:
> > + required:
> > + - memory-region
>
> > + else:
> > + not:
> > + required:
> > + - memory-region
>
> Use
>
> else: properties: memory-region: false
>
> Same for sram.
Accepted will be corrected in V4.
# memory-region
- not:
- required:
- - memory-region
+ properties:
+ memory-region: false

# sram
else:
- not:
- required:
- - sram
+ properties:
+ sram: false

> Sort the allOf after required.
Accepted. Will move allOf after "additionalProperties:"

>
> > +
> > + # sram
> > + - if:
> > + properties:
> > + compatible:
> > + contains:
> > + enum:
> > + - fsl,imx8ulp-se
> > + then:
> > + required:
> > + - sram
> > + else:
> > + not:
> > + required:
> > + - sram
> > +
> > +required:
> > + - compatible
> > + - reg
> > + - mboxes
> > + - mbox-names
> > +
> > +additionalProperties: false
> > +
> > +examples:
> > + - |
> > + firmware {
>
> You've made up these firmware "buses" here, what purpose do they serve,
> other than allowing you to have a reg property?
True.
Additionally, these are firmware nodes, these nodes are semantically put in firmware "buses".

>
> > + #address-cells = <1>;
> > + #size-cells = <0>;
> > + ele-if@0 {
> > + compatible = "fsl,imx8ulp-se";
> > + reg = <0x0>;
>
> What does the reg property even do? Is it ever more than 0?
> Can this information be provided as a mbox cell?
Yes, there are more than 0 nodes for i.MX95 platforms, i.e., total of around 7 such nodes.
Reg property will help to identify the node id, by other kernel management layer like NVMEM (patches to follow).

>
> > + mboxes = <&s4muap 0 0>, <&s4muap 1 0>;
> > + mbox-names = "tx", "rx";
> > + sram = <&sram0>;
> > + memory-region = <&ele_reserved>;
> > + };
> > + };
> > + - |
> > + firmware {
>
> These examples are all basically the same, drop all but one.
Ok, will keep the example of i.MX95.

>
> Thanks,
> Conor.
>
> > + #address-cells = <1>;
> > + #size-cells = <0>;
> > + ele-if@0 {
> > + compatible = "fsl,imx93-se";
> > + reg = <0x0>;
> > + mboxes = <&s4muap 0 0>, <&s4muap 1 0>;
> > + mbox-names = "tx", "rx";
> > + memory-region = <&ele_reserved>;
> > + };
> > + };
> > + - |
> > + firmware {
> > + #address-cells = <1>;
> > + #size-cells = <0>;
> > + ele-if@0 {
> > + compatible = "fsl,imx95-se";
> > + reg = <0x0>;
> > + mboxes = <&ele_mu0 0 0>, <&ele_mu0 1 0>;
> > + mbox-names = "tx", "rx";
> > + };
> > + v2x-if@3 {
> > + compatible = "fsl,imx95-se";
> > + reg = <0x3>;
> > + mboxes = <&v2x_mu 0 0>, <&v2x_mu 1 0>;
> > + mbox-names = "tx", "rx";
> > + };
> > + v2x-if@4 {
> > + compatible = "fsl,imx95-se";
> > + reg = <0x4>;
> > + mboxes = <&v2x_mu6 0 0>, <&v2x_mu6 1 0>;
> > + mbox-names = "tx", "rx";
> > + };
> > + v2x-if@5 {
> > + compatible = "fsl,imx95-se";
> > + reg = <0x5>;
> > + mboxes = <&v2x_mu7 0 0>, <&v2x_mu7 1 0>;
> > + mbox-names = "tx", "rx";
> > + };
> > + };
> > +...
> >
> > --
> > 2.34.1
> >