[RFC PATCH v2 03/15] dt-bindings: misc: Add Arm Core Local Accelerator

[Ryan Roberts]

Arm Core Local Accelerator (CLA) provides a CPU-local interface to
accelerators that access memory through the local CPU's MMU. CLAs whose
accelerators cannot be isolated from each other form an isolation
domain.

Add a binding for arm,cla describing the register range, CPU
association, DMA coherency and isolation domain. Document the
privilege-level register frames, including reduced ranges exposed to
virtual machines, and provide an example of two CLAs sharing a domain.

Signed-off-by: Ryan Roberts <ryan.roberts@xxxxxxx>
---
 .../devicetree/bindings/misc/arm,cla.yaml     | 77 +++++++++++++++++++
 MAINTAINERS                                   |  1 +
 2 files changed, 78 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/misc/arm,cla.yaml

diff --git a/Documentation/devicetree/bindings/misc/arm,cla.yaml b/Documentation/devicetree/bindings/misc/arm,cla.yaml
new file mode 100644
index 000000000000..b86a2befd09a
--- /dev/null
+++ b/Documentation/devicetree/bindings/misc/arm,cla.yaml
@@ -0,0 +1,77 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/misc/arm,cla.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Arm Core Local Accelerator (CLA)
+
+maintainers:
+  - Ryan Roberts <ryan.roberts@xxxxxxx>
+
+description:
+  A Core Local Accelerator (CLA) provides a CPU-local interface to up to eight
+  accelerators. The accelerators access memory through the local CPU's MMU. Each
+  CLA has its own register range, which can only be accessed by its local CPU.
+  Completion is polled through the registers; CLA does not generate interrupts.
+
+properties:
+  compatible:
+    const: arm,cla
+
+  reg:
+    maxItems: 1
+    description:
+      A single contiguous register range starting at the PL0 frame, aligned to
+      256 KiB. Each privilege-level frame occupies 64 KiB, with PL0, PL1, PL2
+      and PL3 at offsets 0, 0x10000, 0x20000 and 0x30000 respectively. The
+      complete range is 256 KiB. Higher-privilege frames may be omitted when
+      unavailable, for example in a virtual machine. The range must include at
+      least PL0 and PL1 when running at EL1 and additionally PL2 when running at
+      EL2.
+
+  cpu:
+    $ref: /schemas/types.yaml#/definitions/phandle
+    description:
+      Phandle to the CPU for which this CLA is local. Only that CPU can access
+      the CLA's registers.
+
+  dma-coherent: true
+
+  arm,domain:
+    $ref: /schemas/types.yaml#/definitions/uint32
+    description:
+      Identifier of the CLA isolation domain. CLAs whose attached accelerators
+      cannot be isolated from each other, for example because they share an
+      inter-accelerator communication bus, must have the same domain ID.
+      Different isolation domains must have different IDs. IDs need not be
+      consecutive. A CLA that can be isolated from all other CLAs has its own
+      domain ID.
+
+required:
+  - compatible
+  - reg
+  - cpu
+  - dma-coherent
+  - arm,domain
+
+additionalProperties: false
+
+examples:
+  - |
+    /* Two CPU-local CLAs in the same isolation domain. */
+    cla@10000000 {
+        compatible = "arm,cla";
+        reg = <0x10000000 0x40000>;
+        cpu = <&cpu0>;
+        dma-coherent;
+        arm,domain = <0>;
+    };
+
+    cla@10040000 {
+        compatible = "arm,cla";
+        reg = <0x10040000 0x40000>;
+        cpu = <&cpu1>;
+        dma-coherent;
+        arm,domain = <0>;
+    };
diff --git a/MAINTAINERS b/MAINTAINERS
index 735f6527f920..98a25b3de9b4 100644
--- a/MAINTAINERS
+++ b/MAINTAINERS
@@ -2213,6 +2213,7 @@ ARM CORE LOCAL ACCELERATOR (CLA) DRIVER
 M:	Ryan Roberts <ryan.roberts@xxxxxxx>
 L:	linux-arm-kernel@xxxxxxxxxxxxxxxxxxx (moderated for non-subscribers)
 S:	Supported
+F:	Documentation/devicetree/bindings/misc/arm,cla.yaml
 F:	Documentation/misc-devices/arm-cla.rst
 F:	drivers/misc/arm-cla/
 
-- 
2.43.0