[RFC PATCH 1/5] dt-bindings: dma: Add CMA Heap bindings

Florent Tomasin
2025-01-30T13:15:11Z

Introduce a CMA Heap dt-binding allowing custom
CMA heap registrations.

* Note to the reviewers:
The patch was used for the development of the protected mode
feature in Panthor CSF kernel driver and is not initially thought
to land in the Linux kernel. It is mostly relevant if someone
wants to reproduce the environment of testing. Please, raise
interest if you think the patch has value in the Linux kernel.

Signed-off-by: Florent Tomasin <florent.tomasin@arm.com>
---
.../devicetree/bindings/dma/linux,cma.yml | 43 +++++++++++++++++++
1 file changed, 43 insertions(+)
create mode 100644 Documentation/devicetree/bindings/dma/linux,cma.yml

diff --git a/Documentation/devicetree/bindings/dma/linux,cma.yml b/Documentation/devicetree/bindings/dma/linux,cma.yml
new file mode 100644
index 000000000000..c532e016bbe5
--- /dev/null
+++ b/Documentation/devicetree/bindings/dma/linux,cma.yml
@@ -0,0 +1,43 @@
+# SPDX-License-Identifier: GPL-2.0-only OR BSD-2-Clause
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/dma/linux-cma.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Custom Linux CMA heap
+
+description:
+ The custom Linux CMA heap device tree node allows registering
+ of multiple CMA heaps.
+
+ The CMA heap name will match the node name of the "memory-region".
+
+properties:
+ compatible:
+ enum:
+ - linux,cma
+
+ memory-region:
+ maxItems: 1
+ description: |
+ Phandle to the reserved memory node associated with the CMA Heap.
+ The reserved memory node must follow this binding convention:
+ - Documentation/devicetree/bindings/reserved-memory/reserved-memory.txt
+
+examples:
+ - |
+ reserved-memory {
+ #address-cells = <2>;
+ #size-cells = <2>;
+
+ custom_cma_heap: custom-cma-heap {
+ compatible = "shared-dma-pool";
+ reg = <0x0 0x90600000 0x0 0x1000000>;
+ reusable;
+ };
+ };
+
+ device_cma_heap: device-cma-heap {
+ compatible = "linux,cma";
+ memory-region = <&custom_cma_heap>;
+ };
--
2.34.1