[PATCH] ARM: dts: exynos: Add energy model for Exynos 5250

[Danny Lin]

This energy model enables the use of energy- and capacity-aware CPU
frequency scaling.

Power and performance measurements were made using my freqbench [1]
benchmark coordinator, which uses EEMBC CoreMark [2] as the workload
and measures power usage using the integrated PMIC's fuel gauge (DS2784
in this case).

The energy model dynamic-power-coefficient values were calculated with
    DPC = µW / MHz / V^2
for each OPP, and averaged across all OPPs within each cluster for the
final coefficient.

A Google Nexus 10 device running a downstream 3.4 kernel was used for
benchmarking to ensure proper frequency scaling and other low-level
controls.

Raw benchmark results can be found in the freqbench repository [3].
Below is a human-readable summary:

===== CPU 1 =====
Frequencies: 200 300 400 500 600 700 800 900 1000 1100 1200 1300 1400 1500 1600 1700

 200:   909     4.5 C/MHz    132 mW   36.2 J    6.9 I/mJ   275.0 s
 300:  1366     4.6 C/MHz    212 mW   38.7 J    6.5 I/mJ   183.0 s
 400:  1821     4.6 C/MHz    286 mW   39.3 J    6.4 I/mJ   137.3 s
 500:  2253     4.5 C/MHz    375 mW   41.7 J    6.0 I/mJ   111.0 s
 600:  2740     4.6 C/MHz    446 mW   40.7 J    6.1 I/mJ    91.2 s
 700:  3199     4.6 C/MHz    513 mW   40.1 J    6.2 I/mJ    78.2 s
 800:  3673     4.6 C/MHz    678 mW   46.1 J    5.4 I/mJ    68.1 s
 900:  4090     4.5 C/MHz    764 mW   46.7 J    5.4 I/mJ    61.1 s
1000:  4586     4.6 C/MHz    878 mW   47.9 J    5.2 I/mJ    54.5 s
1100:  5060     4.6 C/MHz   1084 mW   53.6 J    4.7 I/mJ    49.4 s
1200:  5515     4.6 C/MHz   1225 mW   55.5 J    4.5 I/mJ    45.3 s
1300:  5933     4.6 C/MHz   1396 mW   58.9 J    4.2 I/mJ    42.1 s
1400:  6395     4.6 C/MHz   1662 mW   65.0 J    3.8 I/mJ    39.1 s
1500:  6897     4.6 C/MHz   1895 mW   68.7 J    3.6 I/mJ    36.3 s
1600:  7332     4.6 C/MHz   2198 mW   75.0 J    3.3 I/mJ    34.1 s
1700:  7826     4.6 C/MHz   2497 mW   79.8 J    3.1 I/mJ    31.9 s

[1] https://github.com/kdrag0n/freqbench
[2] https://www.eembc.org/coremark/
[3] https://github.com/kdrag0n/freqbench/tree/master/results/exynos5250/main

Signed-off-by: Danny Lin <danny at kdrag0n.dev>
---
 arch/arm/boot/dts/exynos5250.dtsi | 16 ++++++++++++++++
 1 file changed, 16 insertions(+)

diff --git a/arch/arm/boot/dts/exynos5250.dtsi b/arch/arm/boot/dts/exynos5250.dtsi
index 2ea2caaca4e2..cc2fe0afcfc7 100644
--- a/arch/arm/boot/dts/exynos5250.dtsi
+++ b/arch/arm/boot/dts/exynos5250.dtsi
@@ -58,6 +58,8 @@ cpu0: cpu at 0 {
 			clock-names = "cpu";
 			operating-points-v2 = <&cpu0_opp_table>;
 			#cooling-cells = <2>; /* min followed by max */
+			capacity-dmips-mhz = <1024>;
+			dynamic-power-coefficient = <800>;
 		};
 		cpu1: cpu at 1 {
 			device_type = "cpu";
@@ -67,6 +69,20 @@ cpu1: cpu at 1 {
 			clock-names = "cpu";
 			operating-points-v2 = <&cpu0_opp_table>;
 			#cooling-cells = <2>; /* min followed by max */
+			capacity-dmips-mhz = <1024>;
+			dynamic-power-coefficient = <800>;
+		};
+
+		cpu-map {
+			cluster0 {
+				core0 {
+					cpu = <&cpu0>;
+				};
+
+				core1 {
+					cpu = <&cpu1>;
+				};
+			};
 		};
 	};
 
-- 
2.29.2