xref: /linux/Documentation/devicetree/bindings/thermal/thermal-idle.yaml (revision c532de5a67a70f8533d495f8f2aaa9a0491c3ad0) 
1# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
2# Copyright 2020 Linaro Ltd.
3%YAML 1.2
4---
5$id: http://devicetree.org/schemas/thermal/thermal-idle.yaml#
6$schema: http://devicetree.org/meta-schemas/core.yaml#
7
8title: Thermal idle cooling device
9
10maintainers:
11  - Daniel Lezcano <daniel.lezcano@linaro.org>
12
13description: |
14  The thermal idle cooling device allows the system to passively
15  mitigate the temperature on the device by injecting idle cycles,
16  forcing it to cool down.
17
18  This binding describes the thermal idle node.
19
20properties:
21  $nodename:
22    const: thermal-idle
23    description: |
24      A thermal-idle node describes the idle cooling device properties to
25      cool down efficiently the attached thermal zone.
26
27  '#cooling-cells':
28    const: 2
29    description: |
30      Must be 2, in order to specify minimum and maximum cooling state used in
31      the cooling-maps reference. The first cell is the minimum cooling state
32      and the second cell is the maximum cooling state requested.
33
34  duration-us:
35    description: |
36      The idle duration in microsecond the device should cool down.
37
38  exit-latency-us:
39    description: |
40      The exit latency constraint in microsecond for the injected idle state
41      for the device. It is the latency constraint to apply when selecting an
42      idle state from among all the present ones.
43
44required:
45  - '#cooling-cells'
46
47additionalProperties: false
48
49examples:
50  - |
51    /{
52        #include <dt-bindings/thermal/thermal.h>
53
54        compatible = "foo";
55        model = "foo";
56        #address-cells = <1>;
57        #size-cells = <1>;
58
59        // Example: Combining idle cooling device on big CPUs with cpufreq cooling device
60        cpus {
61            #address-cells = <2>;
62            #size-cells = <0>;
63
64            /* ... */
65
66            cpu_b0: cpu@100 {
67                device_type = "cpu";
68                compatible = "arm,cortex-a72";
69                reg = <0x0 0x100>;
70                enable-method = "psci";
71                capacity-dmips-mhz = <1024>;
72                dynamic-power-coefficient = <436>;
73                #cooling-cells = <2>; /* min followed by max */
74                cpu-idle-states = <&CPU_SLEEP>, <&CLUSTER_SLEEP>;
75                cpu_b0_therm: thermal-idle {
76                    #cooling-cells = <2>;
77                    duration-us = <10000>;
78                    exit-latency-us = <500>;
79                };
80            };
81
82            cpu_b1: cpu@101 {
83                device_type = "cpu";
84                compatible = "arm,cortex-a72";
85                reg = <0x0 0x101>;
86                enable-method = "psci";
87                capacity-dmips-mhz = <1024>;
88                dynamic-power-coefficient = <436>;
89                #cooling-cells = <2>; /* min followed by max */
90                cpu-idle-states = <&CPU_SLEEP>, <&CLUSTER_SLEEP>;
91                cpu_b1_therm: thermal-idle {
92                    #cooling-cells = <2>;
93                    duration-us = <10000>;
94                    exit-latency-us = <500>;
95                };
96            };
97
98            /* ... */
99
100        };
101
102        /* ... */
103
104        thermal_zones {
105            cpu_thermal: cpu {
106                polling-delay-passive = <100>;
107                polling-delay = <1000>;
108
109                /* ... */
110
111                trips {
112                    cpu_alert0: cpu_alert0 {
113                        temperature = <65000>;
114                        hysteresis = <2000>;
115                        type = "passive";
116                    };
117
118                    cpu_alert1: cpu_alert1 {
119                        temperature = <70000>;
120                        hysteresis = <2000>;
121                        type = "passive";
122                    };
123
124                    cpu_alert2: cpu_alert2 {
125                        temperature = <75000>;
126                        hysteresis = <2000>;
127                        type = "passive";
128                    };
129
130                    cpu_crit: cpu_crit {
131                        temperature = <95000>;
132                        hysteresis = <2000>;
133                        type = "critical";
134                    };
135                };
136
137                cooling-maps {
138                    map0 {
139                        trip = <&cpu_alert1>;
140                        cooling-device = <&cpu_b0_therm 0 15 >,
141                                         <&cpu_b1_therm 0 15>;
142                    };
143
144                    map1 {
145                        trip = <&cpu_alert2>;
146                        cooling-device = <&cpu_b0 THERMAL_NO_LIMIT THERMAL_NO_LIMIT>,
147                                         <&cpu_b1 THERMAL_NO_LIMIT THERMAL_NO_LIMIT>;
148                    };
149                };
150            };
151        };
152    };
153