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Message-ID: <f3965cf1-3f0a-15fe-7dd3-e83817a4ba3a@linaro.org>
Date: Wed, 12 Jul 2023 20:38:43 +0200
From: Krzysztof Kozlowski <krzysztof.kozlowski@...aro.org>
To: Pankaj Gupta <pankaj.gupta@....com>, shawnguo@...nel.org,
s.hauer@...gutronix.de, kernel@...gutronix.de, clin@...e.com,
conor+dt@...nel.org, pierre.gondois@....com, ping.bai@....com,
xiaoning.wang@....com, wei.fang@....com, peng.fan@....com,
haibo.chen@....com, festevam@...il.com, linux-imx@....com,
davem@...emloft.net, robh+dt@...nel.org,
krzysztof.kozlowski+dt@...aro.org,
linux-arm-kernel@...ts.infradead.org, devicetree@...r.kernel.org,
linux-kernel@...r.kernel.org, gaurav.jain@....com,
alexander.stein@...tq-group.com, sahil.malhotra@....com,
aisheng.dong@....com, V.Sethi@....com
Subject: Re: [PATCH v4 1/7] dt-bindings: arm: fsl: add se-fw binding doc
On 12/07/2023 14:12, Pankaj Gupta wrote:
> The NXP's i.MX EdgeLock Enclave, a HW IP creating an embedded
> secure enclave within the SoC boundary to enable features like
> - HSM
> - SHE
> - V2X
>
> Communicates via message unit with linux kernel. This driver
> is 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 can communicate on single MU.
>
> It exists on some i.MX processors. e.g. i.MX8ULP, i.MX93 etc.
>
> Signed-off-by: Pankaj Gupta <pankaj.gupta@....com>
> ---
> .../bindings/arm/freescale/fsl,se-fw.yaml | 121 ++++++++++++++++++
> 1 file changed, 121 insertions(+)
> create mode 100644 Documentation/devicetree/bindings/arm/freescale/fsl,se-fw.yaml
>
> diff --git a/Documentation/devicetree/bindings/arm/freescale/fsl,se-fw.yaml b/Documentation/devicetree/bindings/arm/freescale/fsl,se-fw.yaml
> new file mode 100644
> index 000000000000..7567da0b4c21
> --- /dev/null
> +++ b/Documentation/devicetree/bindings/arm/freescale/fsl,se-fw.yaml
> @@ -0,0 +1,121 @@
> +# SPDX-License-Identifier: (GPL-2.0 OR BSD-2-Clause)
> +%YAML 1.2
> +---
> +$id: http://devicetree.org/schemas/arm/freescale/fsl,se-fw.yaml#
> +$schema: http://devicetree.org/meta-schemas/core.yaml#
> +
> +title: NXP i.MX EdgeLock Enclave Firmware (ELEFW)
> +
> +maintainers:
> + - Pankaj Gupta <pankaj.gupta@....com>
> +
> +description: |
> +
> + The NXP's i.MX EdgeLock Enclave, a HW IP creating an embedded
> + secure enclave within the SoC boundary to enable features like
> + - HSM
> + - SHE
> + - V2X
> +
> + It uses message unit to communicate and coordinate to pass messages
> + (e.g., data, status and control) through its interfaces.
> +
> + This driver configures multiple misc-devices on the MU, to exchange
> + messages from User-space application and NXP's Edgelocke Enclave firmware.
> + The driver ensures that the messages must follow the following protocol
> + defined.
> +
> + Non-Secure + Secure
> + |
> + |
> + +---------+ +-------------+ |
> + | ele_mu.c+<---->+imx-mailbox.c| |
> + | | | mailbox.c +<-->+------+ +------+
> + +---+-----+ +-------------+ | MU X +<-->+ ELE |
> + | +------+ +------+
> + +----------------+ |
> + | | |
> + v v |
> + logical logical |
> + receiver waiter |
> + + + |
> + | | |
> + | | |
> + | +----+------+ |
> + | | | |
> + | | | |
> + device_ctx device_ctx device_ctx |
> + |
> + User 0 User 1 User Y |
> + +------+ +------+ +------+ |
> + |misc.c| |misc.c| |misc.c| |
> + kernel space +------+ +------+ +------+ |
> + |
> + +------------------------------------------------------ |
> + | | | |
> + userspace /dev/ele_muXch0 | | |
> + /dev/ele_muXch1 | |
> + /dev/ele_muXchY |
> + |
> +
> + When a user sends a command to the ELE, it registers its device_ctx as
> + waiter of a response from ELE.
> +
> + A user can be registered as receiver of command from the ELE.
> + Create char devices in /dev as channels of the form /dev/ele_muXchY with X
> + the id of the driver and Y for each users. It allows to send and receive
> + messages to the NXP EdgeLock Enclave IP on NXP SoC, where current possible
> + value, i.e., supported SoC(s) are imx8ulp, imx93.
> +
> +properties:
> + compatible:
> + enum:
> + - fsl,imx-ele
> + - fsl,imx93-ele
> +
> + mboxes:
> + description:
> + A list of phandles of TX MU channels followed by a list of phandles of
> + RX MU channels. The number of expected tx and rx channels is 1 TX, and
> + 1 RX channels. All MU channels must be within the same MU instance.
> + Cross instances are not allowed. The MU instance to be used is S4MUAP
> + for imx8ulp & imx93. Users need to ensure that used MU instance does not
> + conflict with other execution environments.
> + items:
> + - description: TX0 MU channel
> + - description: RX0 MU channel
> +
> + mbox-names:
> + items:
> + - const: tx
> + - const: rx
> +
> + fsl,mu-did:
> + $ref: /schemas/types.yaml#/definitions/uint32
> + description:
> + Owner of message-unit, is identified via Domain ID or did.
What is Domain ID?
> +
> + fsl,mu-id:
> + $ref: /schemas/types.yaml#/definitions/uint32
> + description:
> + Identifier to the message-unit among the multiple message-unit that exists on SoC.
> + It is used to create the channels, default to 2
Do you expect then multiple ele nodes in the DTS? What are these two
properties and why they are fixed per SoC, but still embedded in DTS?
> +
> +
Drop stray blank line.
> +required:
> + - compatible
> + - mboxes
> + - mbox-names
> +
> +additionalProperties: false
> +
> +examples:
> + - |
> + ele_mu: ele_mu {
No underscores in node names, generic node names, e.g. firmware. Look at
existing code.
> + compatible = "fsl,imx93-ele";
> + mbox-names = "tx", "rx";
> + mboxes = <&s4muap 2 0
> + &s4muap 3 0>;
Two items, not one.
> + fsl,mu-did = <1>;
> + fsl,mu-id = <1>;
> + };
Plus you clearly did not test the binding and DTS. You said you did some
internal review, so I assume this also includes some testing. How did
you test your DTS?
Best regards,
Krzysztof
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