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 #define pr_fmt(fmt) "cpuidle cooling: " fmt 9 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> 15 #include <linux/of_device.h> 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 33 * @idle_duration_us: CPU idle time to inject in microseconds 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 /** 160 * __cpuidle_cooling_register: register the cooling device 161 * @drv: a cpuidle driver structure pointer 162 * @np: a device node structure pointer used for the thermal binding 163 * 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. 167 * 168 * Return: zero on success, a negative value returned by one of the 169 * underlying subsystem in case of error 170 */ 171 static int __cpuidle_cooling_register(struct device_node *np, 172 struct cpuidle_driver *drv) 173 { 174 struct idle_inject_device *ii_dev; 175 struct cpuidle_cooling_device *idle_cdev; 176 struct thermal_cooling_device *cdev; 177 unsigned int idle_duration_us = TICK_USEC; 178 unsigned int latency_us = UINT_MAX; 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 } 199 200 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); 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 } 216 217 pr_debug("%s: Idle injection set with idle duration=%u, latency=%u\n", 218 dev_name, idle_duration_us, latency_us); 219 220 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 237 * driver and register it to the thermal framework. 238 * 239 * Return: zero on success, or negative value corresponding to the 240 * error detected in the underlying subsystems. 241 */ 242 void cpuidle_cooling_register(struct cpuidle_driver *drv) 243 { 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 } 271 } 272