xref: /freebsd/sys/contrib/device-tree/Bindings/thermal/thermal-idle.yaml (revision e6bfd18d21b225af6a0ed67ceeaf1293b7b9eba5) 
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 binding
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    #include <dt-bindings/thermal/thermal.h>
52
53    // Example: Combining idle cooling device on big CPUs with cpufreq cooling device
54    cpus {
55            #address-cells = <2>;
56            #size-cells = <0>;
57
58            /* ... */
59
60                 cpu_b0: cpu@100 {
61                         device_type = "cpu";
62                         compatible = "arm,cortex-a72";
63                         reg = <0x0 0x100>;
64                         enable-method = "psci";
65                         capacity-dmips-mhz = <1024>;
66                         dynamic-power-coefficient = <436>;
67                         #cooling-cells = <2>; /* min followed by max */
68                         cpu-idle-states = <&CPU_SLEEP>, <&CLUSTER_SLEEP>;
69                         thermal-idle {
70                                 #cooling-cells = <2>;
71                                 duration-us = <10000>;
72                                 exit-latency-us = <500>;
73                         };
74                };
75
76                cpu_b1: cpu@101 {
77                        device_type = "cpu";
78                        compatible = "arm,cortex-a72";
79                        reg = <0x0 0x101>;
80                        enable-method = "psci";
81                        capacity-dmips-mhz = <1024>;
82                        dynamic-power-coefficient = <436>;
83                        #cooling-cells = <2>; /* min followed by max */
84                        cpu-idle-states = <&CPU_SLEEP>, <&CLUSTER_SLEEP>;
85                        thermal-idle {
86                                #cooling-cells = <2>;
87                                duration-us = <10000>;
88                                exit-latency-us = <500>;
89                        };
90                 };
91
92          /* ... */
93
94    };
95
96    /* ... */
97
98    thermal_zones {
99         cpu_thermal: cpu {
100                polling-delay-passive = <100>;
101                polling-delay = <1000>;
102
103                /* ... */
104
105                trips {
106                        cpu_alert0: cpu_alert0 {
107                                    temperature = <65000>;
108                                    hysteresis = <2000>;
109                                    type = "passive";
110                        };
111
112                        cpu_alert1: cpu_alert1 {
113                                    temperature = <70000>;
114                                    hysteresis = <2000>;
115                                    type = "passive";
116                        };
117
118                        cpu_alert2: cpu_alert2 {
119                                    temperature = <75000>;
120                                    hysteresis = <2000>;
121                                    type = "passive";
122                        };
123
124                        cpu_crit: cpu_crit {
125                                    temperature = <95000>;
126                                    hysteresis = <2000>;
127                                    type = "critical";
128                        };
129                };
130
131                cooling-maps {
132                        map0 {
133                             trip = <&cpu_alert1>;
134                             cooling-device = <&{/cpus/cpu@100/thermal-idle} 0 15 >,
135                                              <&{/cpus/cpu@101/thermal-idle} 0 15>;
136                        };
137
138                        map1 {
139                             trip = <&cpu_alert2>;
140                             cooling-device =
141                                        <&cpu_b0 THERMAL_NO_LIMIT THERMAL_NO_LIMIT>,
142                                        <&cpu_b1 THERMAL_NO_LIMIT THERMAL_NO_LIMIT>;
143                       };
144                };
145          };
146    };
147