1 # SPDX-License-Identifier: (GPL-2.0) 1 # SPDX-License-Identifier: (GPL-2.0)
2 # Copyright 2020 Linaro Ltd. 2 # Copyright 2020 Linaro Ltd.
3 %YAML 1.2 3 %YAML 1.2
4 --- 4 ---
5 $id: http://devicetree.org/schemas/thermal/the 5 $id: http://devicetree.org/schemas/thermal/thermal-cooling-devices.yaml#
6 $schema: http://devicetree.org/meta-schemas/co 6 $schema: http://devicetree.org/meta-schemas/core.yaml#
7 7
8 title: Thermal cooling device 8 title: Thermal cooling device
9 9
10 maintainers: 10 maintainers:
11 - Amit Kucheria <amitk@kernel.org> 11 - Amit Kucheria <amitk@kernel.org>
12 12
13 description: | 13 description: |
14 Thermal management is achieved in devicetree 14 Thermal management is achieved in devicetree by describing the sensor hardware
15 and the software abstraction of cooling devi 15 and the software abstraction of cooling devices and thermal zones required to
16 take appropriate action to mitigate thermal 16 take appropriate action to mitigate thermal overload.
17 17
18 The following node types are used to complet 18 The following node types are used to completely describe a thermal management
19 system in devicetree: 19 system in devicetree:
20 - thermal-sensor: device that measures temp 20 - thermal-sensor: device that measures temperature, has SoC-specific bindings
21 - cooling-device: device used to dissipate 21 - cooling-device: device used to dissipate heat either passively or actively
22 - thermal-zones: a container of the followi 22 - thermal-zones: a container of the following node types used to describe all
23 thermal data for the platform 23 thermal data for the platform
24 24
25 This binding describes the cooling devices. 25 This binding describes the cooling devices.
26 26
27 There are essentially two ways to provide co 27 There are essentially two ways to provide control on power dissipation:
28 - Passive cooling: by means of regulating 28 - Passive cooling: by means of regulating device performance. A typical
29 passive cooling mechanism is a CPU that 29 passive cooling mechanism is a CPU that has dynamic voltage and frequency
30 scaling (DVFS), and uses lower frequenci 30 scaling (DVFS), and uses lower frequencies as cooling states.
31 - Active cooling: by means of activating d 31 - Active cooling: by means of activating devices in order to remove the
32 dissipated heat, e.g. regulating fan spe 32 dissipated heat, e.g. regulating fan speeds.
33 33
34 Any cooling device has a range of cooling st 34 Any cooling device has a range of cooling states (i.e. different levels of
35 heat dissipation). They also have a way to d 35 heat dissipation). They also have a way to determine the state of cooling in
36 which the device is. For example, a fan's co 36 which the device is. For example, a fan's cooling states correspond to the
37 different fan speeds possible. Cooling state 37 different fan speeds possible. Cooling states are referred to by single
38 unsigned integers, where larger numbers mean 38 unsigned integers, where larger numbers mean greater heat dissipation. The
39 precise set of cooling states associated wit 39 precise set of cooling states associated with a device should be defined in
40 a particular device's binding. 40 a particular device's binding.
41 41
42 select: true 42 select: true
43 43
44 properties: 44 properties:
45 "#cooling-cells": 45 "#cooling-cells":
46 description: 46 description:
47 Must be 2, in order to specify minimum a 47 Must be 2, in order to specify minimum and maximum cooling state used in
48 the cooling-maps reference. The first ce 48 the cooling-maps reference. The first cell is the minimum cooling state
49 and the second cell is the maximum cooli 49 and the second cell is the maximum cooling state requested.
50 const: 2 50 const: 2
51 51
52 additionalProperties: true 52 additionalProperties: true
53 53
54 examples: 54 examples:
55 - | 55 - |
56 #include <dt-bindings/interrupt-controller 56 #include <dt-bindings/interrupt-controller/arm-gic.h>
57 #include <dt-bindings/thermal/thermal.h> 57 #include <dt-bindings/thermal/thermal.h>
58 58
59 // Example 1: Cpufreq cooling device on CP 59 // Example 1: Cpufreq cooling device on CPU0
60 cpus { 60 cpus {
61 #address-cells = <2>; 61 #address-cells = <2>;
62 #size-cells = <0>; 62 #size-cells = <0>;
63 63
64 CPU0: cpu@0 { 64 CPU0: cpu@0 {
65 device_type = "cpu"; 65 device_type = "cpu";
66 compatible = "qcom,kryo385 66 compatible = "qcom,kryo385";
67 reg = <0x0 0x0>; 67 reg = <0x0 0x0>;
68 enable-method = "psci"; 68 enable-method = "psci";
69 cpu-idle-states = <&LITTLE 69 cpu-idle-states = <&LITTLE_CPU_SLEEP_0>,
70 <&LITTLE 70 <&LITTLE_CPU_SLEEP_1>,
71 <&CLUSTE 71 <&CLUSTER_SLEEP_0>;
72 capacity-dmips-mhz = <607> 72 capacity-dmips-mhz = <607>;
73 dynamic-power-coefficient 73 dynamic-power-coefficient = <100>;
74 qcom,freq-domain = <&cpufr 74 qcom,freq-domain = <&cpufreq_hw 0>;
75 #cooling-cells = <2>; 75 #cooling-cells = <2>;
76 next-level-cache = <&L2_0> 76 next-level-cache = <&L2_0>;
77 L2_0: l2-cache { 77 L2_0: l2-cache {
78 compatible = "cach 78 compatible = "cache";
79 cache-unified; 79 cache-unified;
80 cache-level = <2>; 80 cache-level = <2>;
81 next-level-cache = 81 next-level-cache = <&L3_0>;
82 L3_0: l3-cache { 82 L3_0: l3-cache {
83 compatible 83 compatible = "cache";
84 cache-unif 84 cache-unified;
85 cache-leve 85 cache-level = <3>;
86 }; 86 };
87 }; 87 };
88 }; 88 };
89 89
90 /* ... */ 90 /* ... */
91 91
92 }; 92 };
93 93
94 /* ... */ 94 /* ... */
95 95
96 thermal-zones { 96 thermal-zones {
97 cpu0-thermal { 97 cpu0-thermal {
98 polling-delay-passive = <2 98 polling-delay-passive = <250>;
99 polling-delay = <1000>; 99 polling-delay = <1000>;
100 100
101 thermal-sensors = <&tsens0 101 thermal-sensors = <&tsens0 1>;
102 102
103 trips { 103 trips {
104 cpu0_alert0: trip- 104 cpu0_alert0: trip-point0 {
105 temperatur 105 temperature = <90000>;
106 hysteresis 106 hysteresis = <2000>;
107 type = "pa 107 type = "passive";
108 }; 108 };
109 }; 109 };
110 110
111 cooling-maps { 111 cooling-maps {
112 map0 { 112 map0 {
113 trip = <&c 113 trip = <&cpu0_alert0>;
114 /* Corresp 114 /* Corresponds to 1000MHz in OPP table */
115 cooling-de 115 cooling-device = <&CPU0 5 5>;
116 }; 116 };
117 }; 117 };
118 }; 118 };
119 119
120 /* ... */ 120 /* ... */
121 }; 121 };
122 ... 122 ...
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