[PATCH v5] arm64: dts: exynos7: add support for cpuidle core power down

[Chander Kashyap]

Exynos7 supports multiple idle states. Core power down is one such
idle state, where cores can be powered off independently.

This patch adds support for core power down idle state.

Entry latency for core power down idle state is calculated as follows:
1. Time difference is measured between cpuidle entry and exit.
2. WFI is skipped for measuring the time.
3. Select the worst case time in a set of 100000 cpuidle transactions,
   with varying load.

Exit latency and min residency values are supplied as per HW team.

Signed-off-by: Chander Kashyap <k.chander@xxxxxxxxxxx>
Acked-by: Lorenzo Pieralisi <lorenzo.pieralisi@xxxxxxx>
---
This patch has following dependencies:
	- [PATCH v5 0/8] arch: arm64: Enable support for Samsung Exynos7 SoC
		www.spinics.net/lists/arm-kernel/msg375961.html
Changes in v2:
	- Moved the cpu-idle-state property after reg property
	- removed the status property.
Changes in v3:
	- Added the Entry latency calculation in commit message.
Changes in v4:
	- Corrected the commit message.
	- Corrected the entry latency value.
Changes in v5:
	- Commit message modified

 arch/arm64/boot/dts/exynos/exynos7.dtsi | 17 +++++++++++++++++
 1 file changed, 17 insertions(+)

diff --git a/arch/arm64/boot/dts/exynos/exynos7.dtsi b/arch/arm64/boot/dts/exynos/exynos7.dtsi
index d7a37c3..891eef4 100644
--- a/arch/arm64/boot/dts/exynos/exynos7.dtsi
+++ b/arch/arm64/boot/dts/exynos/exynos7.dtsi
@@ -37,6 +37,7 @@
 			compatible = "arm,cortex-a57", "arm,armv8";
 			reg = <0x0>;
 			enable-method = "psci";
+			cpu-idle-states = <&CPU_SLEEP>;
 		};
 
 		cpu@1 {
@@ -44,6 +45,7 @@
 			compatible = "arm,cortex-a57", "arm,armv8";
 			reg = <0x1>;
 			enable-method = "psci";
+			cpu-idle-states = <&CPU_SLEEP>;
 		};
 
 		cpu@2 {
@@ -51,6 +53,7 @@
 			compatible = "arm,cortex-a57", "arm,armv8";
 			reg = <0x2>;
 			enable-method = "psci";
+			cpu-idle-states = <&CPU_SLEEP>;
 		};
 
 		cpu@3 {
@@ -58,6 +61,20 @@
 			compatible = "arm,cortex-a57", "arm,armv8";
 			reg = <0x3>;
 			enable-method = "psci";
+			cpu-idle-states = <&CPU_SLEEP>;
+		};
+
+		idle-states {
+			entry-method = "arm,psci";
+
+			CPU_SLEEP: cpu-sleep {
+				compatible = "arm,idle-state";
+				local-timer-stop;
+				arm,psci-suspend-param = <0x0010000>;
+				entry-latency-us = <34>;
+				exit-latency-us = <150>;
+				min-residency-us = <2100>;
+			};
 		};
 	};
 
-- 
1.9.1

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