MbedTEE is a Trusted Execution Environment for embedded systems (https://github.com/mbedtee). It communicates with the REE via shared-memory ring buffers using a fixed RPC protocol. Two platform configurations are supported:
- ARM/AArch64 (TrustZone, SMC): two reserved-memory regions (t2r-ring and t2r-shm) plus a GIC SPI edge interrupt for TEE-to-REE notifications. - RISC-V (IMSIC): three reserved-memory regions, adding r2t-ring for REE-to-TEE command submissions; no interrupts property (T2R notifications use IMSIC MSI allocated at runtime).
Signed-off-by: Xing Loong xing.xl.loong@gmail.com --- Changes in v2: - Fix DT binding review comments from Krzysztof Kozlowski: - Drop $nodename, "YAML devicetree binding" wording, property descriptions - Rename compatible string to mbedtee,tee - Rename memory regions: rpc-t2r-ring -> t2r-ring, rpc-t2r-shm -> t2r-shm, rpc-r2t-ring -> r2t-ring - Add memory-region / memory-region-names to required - Simplify allOf constraints (drop redundant else-branch items) - Rewrite description to describe hardware/firmware, not the binding or driver - Drop all irrelevant platform nodes (gic, cpus, reserved-memory containers, reg addresses, riscv wrapper); the ARM example now uses bare interrupts (matching arm,sbsa-gwdt.yaml precedent) with only phandle-required stubs (imsic, t2r-ring, r2t-ring) - Add maxItems: 1 constraint to interrupts property (Sashiko AI review)
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.../bindings/firmware/mbedtee,tee.yaml | 132 ++++++++++++++++++ 1 file changed, 132 insertions(+) create mode 100644 Documentation/devicetree/bindings/firmware/mbedtee,tee.yaml
diff --git a/Documentation/devicetree/bindings/firmware/mbedtee,tee.yaml b/Documentation/devicetree/bindings/firmware/mbedtee,tee.yaml new file mode 100644 index 0000000..62f2522 --- /dev/null +++ b/Documentation/devicetree/bindings/firmware/mbedtee,tee.yaml @@ -0,0 +1,132 @@ +# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause) +%YAML 1.2 +--- +$id: http://devicetree.org/schemas/firmware/mbedtee,tee.yaml# +$schema: http://devicetree.org/meta-schemas/core.yaml# + +title: MbedTEE Trusted Execution Environment + +maintainers: + - Xing Loong xing.xl.loong@gmail.com + +description: | + MbedTEE is a Trusted Execution Environment for embedded systems. + It communicates with the REE (Linux) via shared-memory ring + buffers using a fixed RPC protocol. + + The REE and TEE CPUs sharing the RPC memory must be in a + hardware-coherent domain (same CPU cluster, coherent caches). + + Two or three reserved-memory regions are required: + + t2r-ring ring buffer for TEE-to-REE notifications (all platforms) + t2r-shm shared memory for TEE-to-REE RPC payloads (all platforms) + r2t-ring ring buffer for REE-to-TEE command submissions (RISC-V only) + + On ARM/AArch64 the TEE is invoked via SMC and signals the REE via + a GIC SPI edge interrupt. + + On RISC-V the TEE signals the REE via IMSIC MSI; the REE submits + commands via r2t-ring that the TEE polls. No REE-to-TEE interrupt + is used. No SBI ecall is involved. + +properties: + compatible: + const: mbedtee,tee + + interrupts: + maxItems: 1 + + msi-parent: + maxItems: 1 + + memory-region: + minItems: 2 + maxItems: 3 + # Minimum across platforms (ARM: 2, RISC-V: 3), constrained by allOf below + + memory-region-names: + minItems: 2 + maxItems: 3 + items: + enum: + - t2r-ring + - t2r-shm + - r2t-ring + +required: + - compatible + - memory-region + - memory-region-names + +allOf: + - if: + required: + - interrupts + then: + required: + - interrupts + properties: + msi-parent: false + memory-region: + maxItems: 2 + memory-region-names: + items: + - const: t2r-ring + - const: t2r-shm + else: + required: + - msi-parent + properties: + memory-region: + minItems: 3 + memory-region-names: + items: + - const: t2r-ring + - const: t2r-shm + - const: r2t-ring + +additionalProperties: false + +examples: + - | + /* ARM TrustZone (SMC) */ + #include <dt-bindings/interrupt-controller/arm-gic.h> + + firmware { + mbedtee { + compatible = "mbedtee,tee"; + interrupts = <GIC_SPI 72 IRQ_TYPE_EDGE_RISING>; + memory-region = <&mbedtee_t2r_ring>, <&mbedtee_t2r_shm>; + memory-region-names = "t2r-ring", "t2r-shm"; + }; + }; + + /* memory-region phandle targets */ + mbedtee_t2r_ring: t2r-ring {}; + mbedtee_t2r_shm: t2r-shm {}; + + - | + /* RISC-V IMSIC (ring-buffer polling REE->TEE, MSI TEE->REE) */ + + firmware { + mbedtee { + compatible = "mbedtee,tee"; + msi-parent = <&imsic>; + memory-region = <&rv_t2r_ring>, <&rv_t2r_shm>, + <&rv_r2t_ring>; + memory-region-names = "t2r-ring", "t2r-shm", + "r2t-ring"; + }; + }; + + /* msi-parent phandle target */ + imsic: imsic { + msi-controller; + #msi-cells = <0>; + }; + + /* memory-region phandle targets */ + rv_t2r_ring: t2r-ring {}; + rv_t2r_shm: t2r-shm {}; + rv_r2t_ring: r2t-ring {};