linux-kernel - [RFC PATCH v5 1/6] dt-bindings: exynos-bus: Add documentation for interconnect properties

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Message-Id: <20200529163200.18031-2-s.nawrocki@samsung.com>
Date:   Fri, 29 May 2020 18:31:55 +0200
From:   Sylwester Nawrocki <s.nawrocki@...sung.com>
To:     georgi.djakov@...aro.org, cw00.choi@...sung.com, krzk@...nel.org
Cc:     a.swigon@...sung.com, myungjoo.ham@...sung.com,
        inki.dae@...sung.com, sw0312.kim@...sung.com,
        b.zolnierkie@...sung.com, m.szyprowski@...sung.com,
        s.nawrocki@...sung.com, linux-kernel@...r.kernel.org,
        linux-samsung-soc@...r.kernel.org, dri-devel@...ts.freedesktop.org,
        linux-arm-kernel@...ts.infradead.org
Subject: [RFC PATCH v5 1/6] dt-bindings: exynos-bus: Add documentation for
 interconnect properties

Add documentation for new optional properties in the exynos bus nodes:
samsung,interconnect-parent, #interconnect-cells.
These properties allow to specify the SoC interconnect structure which
then allows the interconnect consumer devices to request specific
bandwidth requirements.

Signed-off-by: Artur Świgoń <a.swigon@...sung.com>
Signed-off-by: Sylwester Nawrocki <s.nawrocki@...sung.com>
---
Changes for v5:
 - exynos,interconnect-parent-node renamed to samsung,interconnect-parent
---
 Documentation/devicetree/bindings/devfreq/exynos-bus.txt | 15 +++++++++++++--
 1 file changed, 13 insertions(+), 2 deletions(-)

diff --git a/Documentation/devicetree/bindings/devfreq/exynos-bus.txt b/Documentation/devicetree/bindings/devfreq/exynos-bus.txt
index e71f752..e0d2daa 100644
--- a/Documentation/devicetree/bindings/devfreq/exynos-bus.txt
+++ b/Documentation/devicetree/bindings/devfreq/exynos-bus.txt
@@ -51,6 +51,11 @@ Optional properties only for parent bus device:
 - exynos,saturation-ratio: the percentage value which is used to calibrate
 			the performance count against total cycle count.

+Optional properties for interconnect functionality (QoS frequency constraints):
+- samsung,interconnect-parent: phandle to the parent interconnect node; for
+  passive devices should point to same node as the exynos,parent-bus property.
+- #interconnect-cells: should be 0
+
 Detailed correlation between sub-blocks and power line according to Exynos SoC:
 - In case of Exynos3250, there are two power line as following:
 	VDD_MIF |--- DMC
@@ -185,8 +190,9 @@ Example1:
 	----------------------------------------------------------

 Example2 :
-	The bus of DMC (Dynamic Memory Controller) block in exynos3250.dtsi
-	is listed below:
+	The bus of DMC (Dynamic Memory Controller) block in exynos3250.dtsi is
+	listed below. An interconnect path "bus_lcd0 -- bus_leftbus -- bus_dmc"
+	is defined for demonstration purposes.

 	bus_dmc: bus_dmc {
 		compatible = "samsung,exynos-bus";
@@ -376,12 +382,15 @@ Example2 :
 	&bus_dmc {
 		devfreq-events = <&ppmu_dmc0_3>, <&ppmu_dmc1_3>;
 		vdd-supply = <&buck1_reg>;	/* VDD_MIF */
+		#interconnect-cells = <0>;
 		status = "okay";
 	};

 	&bus_leftbus {
 		devfreq-events = <&ppmu_leftbus_3>, <&ppmu_rightbus_3>;
 		vdd-supply = <&buck3_reg>;
+		samsung,interconnect-parent = <&bus_dmc>;
+		#interconnect-cells = <0>;
 		status = "okay";
 	};

@@ -392,6 +401,8 @@ Example2 :

 	&bus_lcd0 {
 		devfreq = <&bus_leftbus>;
+		samsung,interconnect-parent = <&bus_leftbus>;
+		#interconnect-cells = <0>;
 		status = "okay";
 	};

--
2.7.4