[PATCH 2/7] dt-bindings: npu: rockchip: allow DVFS and thermal properties

[Igor Paunovic <royalnet026@gmail.com>]

The three NPU cores on the RK3588 are fed by a single clock and a single
supply, and the firmware accepts a fixed set of rates for that clock.
Describing those rates as an operating-points-v2 table is what lets a
driver scale the NPU instead of leaving it at whatever rate the bootloader
set, so allow the property on the core node.

Throttling the NPU from a thermal zone needs the same node to be usable as
a cooling device, so allow #cooling-cells too.

Both properties belong on the core that carries the shared clock, not on
all three: the cores have no clock of their own and cannot be scaled or
throttled independently. Naming one representative node for a shared
frequency domain is the established shape, as in "Cpufreq cooling device
on CPU0" in
Documentation/devicetree/bindings/thermal/thermal-cooling-devices.yaml.

The schema cannot enforce that placement, because all three cores share a
compatible string and a node name pattern, so which core carries them
stays a devicetree convention. That is the same situation as for CPU
cooling, where cpus.yaml does not restrict #cooling-cells to cpu@0 either.

The example gains #cooling-cells; the operating-points-v2 property is
exercised by the RK3588 devicetree later in this series.

Signed-off-by: Igor Paunovic <royalnet026@gmail.com>
Assisted-by: LLM checkpatch dt_binding_check
---
 .../bindings/npu/rockchip,rk3588-rknn-core.yaml        | 10 ++++++++++
 1 file changed, 10 insertions(+)

diff --git a/Documentation/devicetree/bindings/npu/rockchip,rk3588-rknn-core.yaml b/Documentation/devicetree/bindings/npu/rockchip,rk3588-rknn-core.yaml
index caca2a4903cd1..595aacfbf8608 100644
--- a/Documentation/devicetree/bindings/npu/rockchip,rk3588-rknn-core.yaml
+++ b/Documentation/devicetree/bindings/npu/rockchip,rk3588-rknn-core.yaml
@@ -42,6 +42,13 @@ properties:
       - const: npu
       - const: pclk
 
+  "#cooling-cells":
+    description:
+      Present on the core that drives the shared NPU clock, which is the one
+      the operating-points-v2 table below is attached to. The other cores
+      cannot be throttled independently of it.
+    const: 2
+
   interrupts:
     maxItems: 1
 
@@ -50,6 +57,8 @@ properties:
 
   npu-supply: true
 
+  operating-points-v2: true
+
   power-domains:
     maxItems: 1
 
@@ -100,6 +109,7 @@ examples:
         clocks = <&cru ACLK_NPU0>, <&cru HCLK_NPU0>,
                  <&scmi_clk SCMI_CLK_NPU>, <&cru PCLK_NPU_ROOT>;
         clock-names = "aclk", "hclk", "npu", "pclk";
+        #cooling-cells = <2>;
         interrupts = <GIC_SPI 110 IRQ_TYPE_LEVEL_HIGH 0>;
         iommus = <&rknn_mmu_0>;
         npu-supply = <&vdd_npu_s0>;
-- 
2.43.0


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