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1 | // SPDX-License-Identifier: GPL-2.0 |
2 | /* | |
3 | * Copyright (C) 2019 Linaro Limited. | |
4 | * | |
5 | * Author: Daniel Lezcano <daniel.lezcano@linaro.org> | |
6 | * | |
7 | */ | |
8 | #include <linux/cpu_cooling.h> | |
9 | #include <linux/cpuidle.h> | |
10 | #include <linux/err.h> | |
11 | #include <linux/idle_inject.h> | |
12 | #include <linux/idr.h> | |
13 | #include <linux/slab.h> | |
14 | #include <linux/thermal.h> | |
15 | ||
16 | /** | |
17 | * struct cpuidle_cooling_device - data for the idle cooling device | |
18 | * @ii_dev: an atomic to keep track of the last task exiting the idle cycle | |
19 | * @state: a normalized integer giving the state of the cooling device | |
20 | */ | |
21 | struct cpuidle_cooling_device { | |
22 | struct idle_inject_device *ii_dev; | |
23 | unsigned long state; | |
24 | }; | |
25 | ||
26 | static DEFINE_IDA(cpuidle_ida); | |
27 | ||
28 | /** | |
29 | * cpuidle_cooling_runtime - Running time computation | |
30 | * @idle_duration_us: the idle cooling device | |
31 | * @state: a percentile based number | |
32 | * | |
33 | * The running duration is computed from the idle injection duration | |
34 | * which is fixed. If we reach 100% of idle injection ratio, that | |
35 | * means the running duration is zero. If we have a 50% ratio | |
36 | * injection, that means we have equal duration for idle and for | |
37 | * running duration. | |
38 | * | |
39 | * The formula is deduced as follows: | |
40 | * | |
41 | * running = idle x ((100 / ratio) - 1) | |
42 | * | |
43 | * For precision purpose for integer math, we use the following: | |
44 | * | |
45 | * running = (idle x 100) / ratio - idle | |
46 | * | |
47 | * For example, if we have an injected duration of 50%, then we end up | |
48 | * with 10ms of idle injection and 10ms of running duration. | |
49 | * | |
50 | * Return: An unsigned int for a usec based runtime duration. | |
51 | */ | |
52 | static unsigned int cpuidle_cooling_runtime(unsigned int idle_duration_us, | |
53 | unsigned long state) | |
54 | { | |
55 | if (!state) | |
56 | return 0; | |
57 | ||
58 | return ((idle_duration_us * 100) / state) - idle_duration_us; | |
59 | } | |
60 | ||
61 | /** | |
62 | * cpuidle_cooling_get_max_state - Get the maximum state | |
63 | * @cdev : the thermal cooling device | |
64 | * @state : a pointer to the state variable to be filled | |
65 | * | |
66 | * The function always returns 100 as the injection ratio. It is | |
67 | * percentile based for consistency accross different platforms. | |
68 | * | |
69 | * Return: The function can not fail, it is always zero | |
70 | */ | |
71 | static int cpuidle_cooling_get_max_state(struct thermal_cooling_device *cdev, | |
72 | unsigned long *state) | |
73 | { | |
74 | /* | |
75 | * Depending on the configuration or the hardware, the running | |
76 | * cycle and the idle cycle could be different. We want to | |
77 | * unify that to an 0..100 interval, so the set state | |
78 | * interface will be the same whatever the platform is. | |
79 | * | |
80 | * The state 100% will make the cluster 100% ... idle. A 0% | |
81 | * injection ratio means no idle injection at all and 50% | |
82 | * means for 10ms of idle injection, we have 10ms of running | |
83 | * time. | |
84 | */ | |
85 | *state = 100; | |
86 | ||
87 | return 0; | |
88 | } | |
89 | ||
90 | /** | |
91 | * cpuidle_cooling_get_cur_state - Get the current cooling state | |
92 | * @cdev: the thermal cooling device | |
93 | * @state: a pointer to the state | |
94 | * | |
95 | * The function just copies the state value from the private thermal | |
96 | * cooling device structure, the mapping is 1 <-> 1. | |
97 | * | |
98 | * Return: The function can not fail, it is always zero | |
99 | */ | |
100 | static int cpuidle_cooling_get_cur_state(struct thermal_cooling_device *cdev, | |
101 | unsigned long *state) | |
102 | { | |
103 | struct cpuidle_cooling_device *idle_cdev = cdev->devdata; | |
104 | ||
105 | *state = idle_cdev->state; | |
106 | ||
107 | return 0; | |
108 | } | |
109 | ||
110 | /** | |
111 | * cpuidle_cooling_set_cur_state - Set the current cooling state | |
112 | * @cdev: the thermal cooling device | |
113 | * @state: the target state | |
114 | * | |
115 | * The function checks first if we are initiating the mitigation which | |
116 | * in turn wakes up all the idle injection tasks belonging to the idle | |
117 | * cooling device. In any case, it updates the internal state for the | |
118 | * cooling device. | |
119 | * | |
120 | * Return: The function can not fail, it is always zero | |
121 | */ | |
122 | static int cpuidle_cooling_set_cur_state(struct thermal_cooling_device *cdev, | |
123 | unsigned long state) | |
124 | { | |
125 | struct cpuidle_cooling_device *idle_cdev = cdev->devdata; | |
126 | struct idle_inject_device *ii_dev = idle_cdev->ii_dev; | |
127 | unsigned long current_state = idle_cdev->state; | |
128 | unsigned int runtime_us, idle_duration_us; | |
129 | ||
130 | idle_cdev->state = state; | |
131 | ||
132 | idle_inject_get_duration(ii_dev, &runtime_us, &idle_duration_us); | |
133 | ||
134 | runtime_us = cpuidle_cooling_runtime(idle_duration_us, state); | |
135 | ||
136 | idle_inject_set_duration(ii_dev, runtime_us, idle_duration_us); | |
137 | ||
138 | if (current_state == 0 && state > 0) { | |
139 | idle_inject_start(ii_dev); | |
140 | } else if (current_state > 0 && !state) { | |
141 | idle_inject_stop(ii_dev); | |
142 | } | |
143 | ||
144 | return 0; | |
145 | } | |
146 | ||
147 | /** | |
148 | * cpuidle_cooling_ops - thermal cooling device ops | |
149 | */ | |
150 | static struct thermal_cooling_device_ops cpuidle_cooling_ops = { | |
151 | .get_max_state = cpuidle_cooling_get_max_state, | |
152 | .get_cur_state = cpuidle_cooling_get_cur_state, | |
153 | .set_cur_state = cpuidle_cooling_set_cur_state, | |
154 | }; | |
155 | ||
156 | /** | |
157 | * cpuidle_of_cooling_register - Idle cooling device initialization function | |
158 | * @drv: a cpuidle driver structure pointer | |
159 | * @np: a node pointer to a device tree cooling device node | |
160 | * | |
161 | * This function is in charge of creating a cooling device per cpuidle | |
162 | * driver and register it to thermal framework. | |
163 | * | |
164 | * Return: zero on success, or negative value corresponding to the | |
165 | * error detected in the underlying subsystems. | |
166 | */ | |
167 | int cpuidle_of_cooling_register(struct device_node *np, | |
168 | struct cpuidle_driver *drv) | |
169 | { | |
170 | struct idle_inject_device *ii_dev; | |
171 | struct cpuidle_cooling_device *idle_cdev; | |
172 | struct thermal_cooling_device *cdev; | |
173 | char dev_name[THERMAL_NAME_LENGTH]; | |
174 | int id, ret; | |
175 | ||
176 | idle_cdev = kzalloc(sizeof(*idle_cdev), GFP_KERNEL); | |
177 | if (!idle_cdev) { | |
178 | ret = -ENOMEM; | |
179 | goto out; | |
180 | } | |
181 | ||
182 | id = ida_simple_get(&cpuidle_ida, 0, 0, GFP_KERNEL); | |
183 | if (id < 0) { | |
184 | ret = id; | |
185 | goto out_kfree; | |
186 | } | |
187 | ||
188 | ii_dev = idle_inject_register(drv->cpumask); | |
189 | if (!ii_dev) { | |
190 | ret = -EINVAL; | |
191 | goto out_id; | |
192 | } | |
193 | ||
194 | idle_inject_set_duration(ii_dev, TICK_USEC, TICK_USEC); | |
195 | ||
196 | idle_cdev->ii_dev = ii_dev; | |
197 | ||
198 | snprintf(dev_name, sizeof(dev_name), "thermal-idle-%d", id); | |
199 | ||
200 | cdev = thermal_of_cooling_device_register(np, dev_name, idle_cdev, | |
201 | &cpuidle_cooling_ops); | |
202 | if (IS_ERR(cdev)) { | |
203 | ret = PTR_ERR(cdev); | |
204 | goto out_unregister; | |
205 | } | |
206 | ||
207 | return 0; | |
208 | ||
209 | out_unregister: | |
210 | idle_inject_unregister(ii_dev); | |
211 | out_id: | |
212 | ida_simple_remove(&cpuidle_ida, id); | |
213 | out_kfree: | |
214 | kfree(idle_cdev); | |
215 | out: | |
216 | return ret; | |
217 | } | |
218 | ||
219 | /** | |
220 | * cpuidle_cooling_register - Idle cooling device initialization function | |
221 | * @drv: a cpuidle driver structure pointer | |
222 | * | |
223 | * This function is in charge of creating a cooling device per cpuidle | |
224 | * driver and register it to thermal framework. | |
225 | * | |
226 | * Return: zero on success, or negative value corresponding to the | |
227 | * error detected in the underlying subsystems. | |
228 | */ | |
229 | int cpuidle_cooling_register(struct cpuidle_driver *drv) | |
230 | { | |
231 | return cpuidle_of_cooling_register(NULL, drv); | |
232 | } |