Re: [PATCH v19 4/6] dt-bindings: remoteproc: Add compatibility for TEE support
From: Sumit Garg <sumit.garg@kernel.org>
Date: 2025-09-16 09:14:57
Also in:
linux-devicetree, linux-remoteproc, lkml, op-tee
Hi Arnaud, First of all apologies for such a late review comment as previously I wasn't CCed or involved in the review of this patch-set. In case any of my following comments have been discussed in the past then feel free to point me at relevant discussions. On Wed, Jun 25, 2025 at 11:40:26AM +0200, Arnaud Pouliquen wrote:
The "st,stm32mp1-m4-tee" compatible is utilized in a system configuration where the Cortex-M4 firmware is loaded by the Trusted Execution Environment (TEE).
Having a DT based compatible for a TEE service to me just feels like it is redundant here. I can see you have also used a TEE bus based device too but that is not being properly used. I know subsystems like remoteproc, SCMI and others heavily rely on DT to hardcode properties of system firmware which are rather better to be discovered dynamically. So I have an open question for you and the remoteproc subsystem maintainers being: Is it feasible to rather leverage the benefits of a fully discoverable TEE bus rather than relying on platform bus/ DT to hardcode firmware properties?
For instance, this compatible is used in both the Linux and OP-TEE device trees: - In OP-TEE, a node is defined in the device tree with the "st,stm32mp1-m4-tee" compatible to support signed remoteproc firmware. Based on DT properties, the OP-TEE remoteproc framework is initiated to expose a trusted application service to authenticate and load the remote processor firmware provided by the Linux remoteproc framework, as well as to start and stop the remote processor. - In Linux, when the compatibility is set, the Cortex-M resets should not be declared in the device tree. In such a configuration, the reset is managed by the OP-TEE remoteproc driver and is no longer accessible from the Linux kernel. Associated with this new compatible, add the "st,proc-id" property to identify the remote processor. This ID is used to define a unique ID, common between Linux, U-Boot, and OP-TEE, to identify a coprocessor.
This "st,proc-id" is just one such property which can rather be directly probed from the TEE/OP-TEE service rather than hardcoding it in DT here. I think the same will apply to other properties as well. -Sumit
quoted hunk ↗ jump to hunk
This ID will be used in requests to the OP-TEE remoteproc Trusted Application to specify the remote processor. Signed-off-by: Arnaud Pouliquen <arnaud.pouliquen@foss.st.com> Reviewed-by: Rob Herring (Arm) <robh@kernel.org> --- .../bindings/remoteproc/st,stm32-rproc.yaml | 58 ++++++++++++++++--- 1 file changed, 50 insertions(+), 8 deletions(-)diff --git a/Documentation/devicetree/bindings/remoteproc/st,stm32-rproc.yaml b/Documentation/devicetree/bindings/remoteproc/st,stm32-rproc.yaml index 843679c557e7..58da07e536fc 100644 --- a/Documentation/devicetree/bindings/remoteproc/st,stm32-rproc.yaml +++ b/Documentation/devicetree/bindings/remoteproc/st,stm32-rproc.yaml@@ -16,7 +16,12 @@ maintainers: properties: compatible: - const: st,stm32mp1-m4 + enum: + - st,stm32mp1-m4 + - st,stm32mp1-m4-tee + description: + Use "st,stm32mp1-m4" for the Cortex-M4 coprocessor management by non-secure context + Use "st,stm32mp1-m4-tee" for the Cortex-M4 coprocessor management by secure context reg: description:@@ -43,6 +48,10 @@ properties: - description: The offset of the hold boot setting register - description: The field mask of the hold boot + st,proc-id: + description: remote processor identifier + $ref: /schemas/types.yaml#/definitions/uint32 + st,syscfg-tz: deprecated: true description:@@ -146,21 +155,43 @@ properties: required: - compatible - reg - - resets allOf: - if: properties: - reset-names: - not: - contains: - const: hold_boot + compatible: + contains: + const: st,stm32mp1-m4 then: + if: + properties: + reset-names: + not: + contains: + const: hold_boot + then: + required: + - st,syscfg-holdboot + else: + properties: + st,syscfg-holdboot: false + required: + - reset-names required: - - st,syscfg-holdboot - else: + - resets + + - if: + properties: + compatible: + contains: + const: st,stm32mp1-m4-tee + then: properties: st,syscfg-holdboot: false + reset-names: false + resets: false + required: + - st,proc-id additionalProperties: false@@ -192,5 +223,16 @@ examples: st,syscfg-rsc-tbl = <&tamp 0x144 0xFFFFFFFF>; st,syscfg-m4-state = <&tamp 0x148 0xFFFFFFFF>; }; + - | + #include <dt-bindings/reset/stm32mp1-resets.h> + m4@10000000 { + compatible = "st,stm32mp1-m4-tee"; + reg = <0x10000000 0x40000>, + <0x30000000 0x40000>, + <0x38000000 0x10000>; + st,proc-id = <0>; + st,syscfg-rsc-tbl = <&tamp 0x144 0xFFFFFFFF>; + st,syscfg-m4-state = <&tamp 0x148 0xFFFFFFFF>; + }; ...-- 2.25.1