linux-kernel - [PATCHv3 8/8] Documentation: dt: devfreq: Add device tree binding of Exynos4 busfreq

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Date:	Fri, 14 Mar 2014 18:30:08 +0900
From:	Chanwoo Choi <cw00.choi@...sung.com>
To:	myungjoo.ham@...sung.com, kyungmin.park@...sung.com
Cc:	rafael.j.wysocki@...el.com, nm@...com, b.zolnierkie@...saung.com,
	pawel.moll@....com, mark.rutland@....com, swarren@...dotorg.org,
	ijc+devicetree@...lion.org.uk, linux-pm@...r.kernel.org,
	linux-kernel@...r.kernel.org, linux-samsung-soc@...r.kernel.org,
	devicetree@...r.kernel.org, linux-doc@...r.kernel.org,
	Chanwoo Choi <cw00.choi@...sung.com>
Subject: [PATCHv3 8/8] Documentation: dt: devfreq: Add device tree binding of
 Exynos4 busfreq

This patch introduce device tree binding for the Exynos4's busfreq driver.
The Exynos4's busfreq driver support DVFS(Dynamic Voltage Frequency Scaling)
of Exynos4 memory bus to optimize power-consumption on runtime state.
Exynos4's busfreq driver need the utilization of memory bus. So, busfreq driver
use PPMU_DMC0/PPMU_DMC1 IP among various PPMU(Performance Profiling Monitoring
Units) which provide the data of read/write counters on memory bus. This driver
adjust the frequency/voltage of memory bus according to PPMU_DMC0/PPMU_DMC1
counters.

Signed-off-by: Chanwoo Choi <cw00.choi@...sung.com>
---
 .../devicetree/bindings/devfreq/exynos4_bus.txt    | 50 ++++++++++++++++++++++
 1 file changed, 50 insertions(+)
 create mode 100644 Documentation/devicetree/bindings/devfreq/exynos4_bus.txt

diff --git a/Documentation/devicetree/bindings/devfreq/exynos4_bus.txt b/Documentation/devicetree/bindings/devfreq/exynos4_bus.txt
new file mode 100644
index 0000000..bd397ed
--- /dev/null
+++ b/Documentation/devicetree/bindings/devfreq/exynos4_bus.txt
@@ -0,0 +1,50 @@
+
+Exynos4 Memory Bus frequency driver
+-----------------------------------
+
+Exynos4 SoC need Busfreq (Memory Bus frequency) driver to support DVFS (Dynamic
+Voltage Frequency Scaling) of Exynos4 SoC's memory bus. This driver controls
+dynamically the frequency/voltage of memory bus to optimize power-consumption
+of memory bus. When checking the utilization of memory bus, Exynos4's busfreq
+driver uses PPMU_DMC0/PPMU_DMC1 (Performance Profiling Monitoring Units)
+which provide the data of read/write counters on memory bus.
+
+Required properties:
+- compatible	: should contain Exynos4 SoC type as following:
+		  - "samsung,exynos4210-busfreq" for Exynos4210
+		  - "samsung,exynos4x12-busfreq" for Exynos4x12
+- reg		: physical address of PPMU_DMC0/PPMU_DMC1 register and length
+		  for memory mapping
+- clocks	: phandles to clock-controller and clock number of PPMU_DMC0
+		  /PPMU_DMC1
+- clock-names	: clock names for PPMU_DMC0/PPMU_DMC1
+		  - "ppmudmc0" for PPMU_DMC0
+		  - "ppmudmc1" for PPMU_DMC1
+- vdd_int-supply: regulator for interface block of Exynos4 SoC
+
+Optional properties:
+- vdd_mif-supply: regulator for DMC block if using Exynos4x12 SoC
+
+Example:
+For Exynos4210 busfreq,
+
+	busfreq@...A0000 {
+		compatible = "samsung,exynos4210-busfreq";
+		reg = <0x106A0000 0x2000>, <0x106B0000 0x2000>;
+		clocks = <&clock CLK_PPMUDMC0>, <&clock CLK_PPMUDMC1>;
+		clock-names = "ppmudmc0", "ppmudmc1";
+
+		vdd_int-supply = <&buck3_reg>;
+	};
+
+For Exynos4x12 busfreq,
+
+	busfreq@...A0000 {
+		compatible = "samsung,exynos4x12-busfreq";
+		reg = <0x106A0000 0x2000>, <0x106B0000 0x2000>;
+		clocks = <&clock CLK_PPMUDMC0>, <&clock CLK_PPMUDMC1>;
+		clock-names = "ppmudmc0", "ppmudmc1";
+
+		vdd_int-supply = <&buck3_reg>;
+		vdd_mif-suppy = <&buck1_reg>;
+	};
-- 
1.8.0

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