[PATCH v2 06/11] 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 a core node to be usable as
a cooling device, so allow #cooling-cells too.

The OPP table belongs on every core, with opp-shared: the cores have no
clock of their own, and one shared table for one shared clock is the same
shape a CPU cluster uses. #cooling-cells goes on one core only, the one a
thermal zone's cooling map names, because the cores cannot be 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 which core carries #cooling-cells, because all
three cores share a compatible string and a node name pattern, so that
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.

Assisted-by: LLM checkpatch dt_binding_check
Signed-off-by: Igor Paunovic <royalnet026@gmail.com>
Acked-by: Conor Dooley <conor.dooley@microchip.com>
---
v2: the text on where the properties go is rewritten for opp-shared on
all three cores, following Nicolas Dufresne's review of v1 3/7. The
only change to the schema file is the wording of the #cooling-cells
description; the constraints and the example are unchanged. Conor, your
Ack is kept on that basis; please say if it no longer holds.

 .../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..beba1896156f5 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 one core only, the first, which stands for the shared NPU
+      clock as a cooling device. The other cores have no clock of their own
+      and 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