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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 | */ | |
dfd0bda3 DL |
8 | #define pr_fmt(fmt) "cpuidle cooling: " fmt |
9 | ||
a4c428e5 DL |
10 | #include <linux/cpu_cooling.h> |
11 | #include <linux/cpuidle.h> | |
12 | #include <linux/err.h> | |
13 | #include <linux/idle_inject.h> | |
14 | #include <linux/idr.h> | |
dfd0bda3 | 15 | #include <linux/of_device.h> |
a4c428e5 DL |
16 | #include <linux/slab.h> |
17 | #include <linux/thermal.h> | |
18 | ||
19 | /** | |
20 | * struct cpuidle_cooling_device - data for the idle cooling device | |
21 | * @ii_dev: an atomic to keep track of the last task exiting the idle cycle | |
22 | * @state: a normalized integer giving the state of the cooling device | |
23 | */ | |
24 | struct cpuidle_cooling_device { | |
25 | struct idle_inject_device *ii_dev; | |
26 | unsigned long state; | |
27 | }; | |
28 | ||
29 | static DEFINE_IDA(cpuidle_ida); | |
30 | ||
31 | /** | |
32 | * cpuidle_cooling_runtime - Running time computation | |
585834a5 | 33 | * @idle_duration_us: CPU idle time to inject in microseconds |
a4c428e5 DL |
34 | * @state: a percentile based number |
35 | * | |
36 | * The running duration is computed from the idle injection duration | |
37 | * which is fixed. If we reach 100% of idle injection ratio, that | |
38 | * means the running duration is zero. If we have a 50% ratio | |
39 | * injection, that means we have equal duration for idle and for | |
40 | * running duration. | |
41 | * | |
42 | * The formula is deduced as follows: | |
43 | * | |
44 | * running = idle x ((100 / ratio) - 1) | |
45 | * | |
46 | * For precision purpose for integer math, we use the following: | |
47 | * | |
48 | * running = (idle x 100) / ratio - idle | |
49 | * | |
50 | * For example, if we have an injected duration of 50%, then we end up | |
51 | * with 10ms of idle injection and 10ms of running duration. | |
52 | * | |
53 | * Return: An unsigned int for a usec based runtime duration. | |
54 | */ | |
55 | static unsigned int cpuidle_cooling_runtime(unsigned int idle_duration_us, | |
56 | unsigned long state) | |
57 | { | |
58 | if (!state) | |
59 | return 0; | |
60 | ||
61 | return ((idle_duration_us * 100) / state) - idle_duration_us; | |
62 | } | |
63 | ||
64 | /** | |
65 | * cpuidle_cooling_get_max_state - Get the maximum state | |
66 | * @cdev : the thermal cooling device | |
67 | * @state : a pointer to the state variable to be filled | |
68 | * | |
69 | * The function always returns 100 as the injection ratio. It is | |
70 | * percentile based for consistency accross different platforms. | |
71 | * | |
72 | * Return: The function can not fail, it is always zero | |
73 | */ | |
74 | static int cpuidle_cooling_get_max_state(struct thermal_cooling_device *cdev, | |
75 | unsigned long *state) | |
76 | { | |
77 | /* | |
78 | * Depending on the configuration or the hardware, the running | |
79 | * cycle and the idle cycle could be different. We want to | |
80 | * unify that to an 0..100 interval, so the set state | |
81 | * interface will be the same whatever the platform is. | |
82 | * | |
83 | * The state 100% will make the cluster 100% ... idle. A 0% | |
84 | * injection ratio means no idle injection at all and 50% | |
85 | * means for 10ms of idle injection, we have 10ms of running | |
86 | * time. | |
87 | */ | |
88 | *state = 100; | |
89 | ||
90 | return 0; | |
91 | } | |
92 | ||
93 | /** | |
94 | * cpuidle_cooling_get_cur_state - Get the current cooling state | |
95 | * @cdev: the thermal cooling device | |
96 | * @state: a pointer to the state | |
97 | * | |
98 | * The function just copies the state value from the private thermal | |
99 | * cooling device structure, the mapping is 1 <-> 1. | |
100 | * | |
101 | * Return: The function can not fail, it is always zero | |
102 | */ | |
103 | static int cpuidle_cooling_get_cur_state(struct thermal_cooling_device *cdev, | |
104 | unsigned long *state) | |
105 | { | |
106 | struct cpuidle_cooling_device *idle_cdev = cdev->devdata; | |
107 | ||
108 | *state = idle_cdev->state; | |
109 | ||
110 | return 0; | |
111 | } | |
112 | ||
113 | /** | |
114 | * cpuidle_cooling_set_cur_state - Set the current cooling state | |
115 | * @cdev: the thermal cooling device | |
116 | * @state: the target state | |
117 | * | |
118 | * The function checks first if we are initiating the mitigation which | |
119 | * in turn wakes up all the idle injection tasks belonging to the idle | |
120 | * cooling device. In any case, it updates the internal state for the | |
121 | * cooling device. | |
122 | * | |
123 | * Return: The function can not fail, it is always zero | |
124 | */ | |
125 | static int cpuidle_cooling_set_cur_state(struct thermal_cooling_device *cdev, | |
126 | unsigned long state) | |
127 | { | |
128 | struct cpuidle_cooling_device *idle_cdev = cdev->devdata; | |
129 | struct idle_inject_device *ii_dev = idle_cdev->ii_dev; | |
130 | unsigned long current_state = idle_cdev->state; | |
131 | unsigned int runtime_us, idle_duration_us; | |
132 | ||
133 | idle_cdev->state = state; | |
134 | ||
135 | idle_inject_get_duration(ii_dev, &runtime_us, &idle_duration_us); | |
136 | ||
137 | runtime_us = cpuidle_cooling_runtime(idle_duration_us, state); | |
138 | ||
139 | idle_inject_set_duration(ii_dev, runtime_us, idle_duration_us); | |
140 | ||
141 | if (current_state == 0 && state > 0) { | |
142 | idle_inject_start(ii_dev); | |
143 | } else if (current_state > 0 && !state) { | |
144 | idle_inject_stop(ii_dev); | |
145 | } | |
146 | ||
147 | return 0; | |
148 | } | |
149 | ||
150 | /** | |
151 | * cpuidle_cooling_ops - thermal cooling device ops | |
152 | */ | |
153 | static struct thermal_cooling_device_ops cpuidle_cooling_ops = { | |
154 | .get_max_state = cpuidle_cooling_get_max_state, | |
155 | .get_cur_state = cpuidle_cooling_get_cur_state, | |
156 | .set_cur_state = cpuidle_cooling_set_cur_state, | |
157 | }; | |
158 | ||
159 | /** | |
dfd0bda3 | 160 | * __cpuidle_cooling_register: register the cooling device |
a4c428e5 | 161 | * @drv: a cpuidle driver structure pointer |
dfd0bda3 | 162 | * @np: a device node structure pointer used for the thermal binding |
a4c428e5 | 163 | * |
dfd0bda3 DL |
164 | * This function is in charge of allocating the cpuidle cooling device |
165 | * structure, the idle injection, initialize them and register the | |
166 | * cooling device to the thermal framework. | |
a4c428e5 | 167 | * |
dfd0bda3 DL |
168 | * Return: zero on success, a negative value returned by one of the |
169 | * underlying subsystem in case of error | |
a4c428e5 | 170 | */ |
dfd0bda3 DL |
171 | static int __cpuidle_cooling_register(struct device_node *np, |
172 | struct cpuidle_driver *drv) | |
a4c428e5 DL |
173 | { |
174 | struct idle_inject_device *ii_dev; | |
175 | struct cpuidle_cooling_device *idle_cdev; | |
176 | struct thermal_cooling_device *cdev; | |
dfd0bda3 DL |
177 | unsigned int idle_duration_us = TICK_USEC; |
178 | unsigned int latency_us = UINT_MAX; | |
a4c428e5 DL |
179 | char dev_name[THERMAL_NAME_LENGTH]; |
180 | int id, ret; | |
181 | ||
182 | idle_cdev = kzalloc(sizeof(*idle_cdev), GFP_KERNEL); | |
183 | if (!idle_cdev) { | |
184 | ret = -ENOMEM; | |
185 | goto out; | |
186 | } | |
187 | ||
188 | id = ida_simple_get(&cpuidle_ida, 0, 0, GFP_KERNEL); | |
189 | if (id < 0) { | |
190 | ret = id; | |
191 | goto out_kfree; | |
192 | } | |
193 | ||
194 | ii_dev = idle_inject_register(drv->cpumask); | |
195 | if (!ii_dev) { | |
196 | ret = -EINVAL; | |
197 | goto out_id; | |
198 | } | |
199 | ||
dfd0bda3 DL |
200 | of_property_read_u32(np, "duration-us", &idle_duration_us); |
201 | of_property_read_u32(np, "exit-latency-us", &latency_us); | |
202 | ||
203 | idle_inject_set_duration(ii_dev, TICK_USEC, idle_duration_us); | |
204 | idle_inject_set_latency(ii_dev, latency_us); | |
a4c428e5 DL |
205 | |
206 | idle_cdev->ii_dev = ii_dev; | |
207 | ||
208 | snprintf(dev_name, sizeof(dev_name), "thermal-idle-%d", id); | |
209 | ||
210 | cdev = thermal_of_cooling_device_register(np, dev_name, idle_cdev, | |
211 | &cpuidle_cooling_ops); | |
212 | if (IS_ERR(cdev)) { | |
213 | ret = PTR_ERR(cdev); | |
214 | goto out_unregister; | |
215 | } | |
216 | ||
dfd0bda3 DL |
217 | pr_debug("%s: Idle injection set with idle duration=%u, latency=%u\n", |
218 | dev_name, idle_duration_us, latency_us); | |
219 | ||
a4c428e5 DL |
220 | return 0; |
221 | ||
222 | out_unregister: | |
223 | idle_inject_unregister(ii_dev); | |
224 | out_id: | |
225 | ida_simple_remove(&cpuidle_ida, id); | |
226 | out_kfree: | |
227 | kfree(idle_cdev); | |
228 | out: | |
229 | return ret; | |
230 | } | |
231 | ||
232 | /** | |
233 | * cpuidle_cooling_register - Idle cooling device initialization function | |
234 | * @drv: a cpuidle driver structure pointer | |
235 | * | |
236 | * This function is in charge of creating a cooling device per cpuidle | |
dfd0bda3 | 237 | * driver and register it to the thermal framework. |
a4c428e5 DL |
238 | * |
239 | * Return: zero on success, or negative value corresponding to the | |
240 | * error detected in the underlying subsystems. | |
241 | */ | |
dfd0bda3 | 242 | void cpuidle_cooling_register(struct cpuidle_driver *drv) |
a4c428e5 | 243 | { |
dfd0bda3 DL |
244 | struct device_node *cooling_node; |
245 | struct device_node *cpu_node; | |
246 | int cpu, ret; | |
247 | ||
248 | for_each_cpu(cpu, drv->cpumask) { | |
249 | ||
250 | cpu_node = of_cpu_device_node_get(cpu); | |
251 | ||
252 | cooling_node = of_get_child_by_name(cpu_node, "thermal-idle"); | |
253 | ||
254 | of_node_put(cpu_node); | |
255 | ||
256 | if (!cooling_node) { | |
257 | pr_debug("'thermal-idle' node not found for cpu%d\n", cpu); | |
258 | continue; | |
259 | } | |
260 | ||
261 | ret = __cpuidle_cooling_register(cooling_node, drv); | |
262 | ||
263 | of_node_put(cooling_node); | |
264 | ||
265 | if (ret) { | |
266 | pr_err("Failed to register the cpuidle cooling device" \ | |
267 | "for cpu%d: %d\n", cpu, ret); | |
268 | break; | |
269 | } | |
270 | } | |
a4c428e5 | 271 | } |