1 // SPDX-License-Identifier: GPL-2.0
3 * devfreq_cooling: Thermal cooling device implementation for devices using
6 * Copyright (C) 2014-2015 ARM Limited
9 * - If OPPs are added or removed after devfreq cooling has
10 * registered, the devfreq cooling won't react to it.
13 #include <linux/devfreq.h>
14 #include <linux/devfreq_cooling.h>
15 #include <linux/export.h>
16 #include <linux/idr.h>
17 #include <linux/slab.h>
18 #include <linux/pm_opp.h>
19 #include <linux/pm_qos.h>
20 #include <linux/thermal.h>
22 #include <trace/events/thermal.h>
24 #define HZ_PER_KHZ 1000
25 #define SCALE_ERROR_MITIGATION 100
27 static DEFINE_IDA(devfreq_ida);
30 * struct devfreq_cooling_device - Devfreq cooling device
31 * @id: unique integer value corresponding to each
32 * devfreq_cooling_device registered.
33 * @cdev: Pointer to associated thermal cooling device.
34 * @devfreq: Pointer to associated devfreq device.
35 * @cooling_state: Current cooling state.
36 * @power_table: Pointer to table with maximum power draw for each
37 * cooling state. State is the index into the table, and
39 * @freq_table: Pointer to a table with the frequencies sorted in descending
40 * order. You can index the table by cooling device state
41 * @freq_table_size: Size of the @freq_table and @power_table
42 * @power_ops: Pointer to devfreq_cooling_power, used to generate the
44 * @res_util: Resource utilization scaling factor for the power.
45 * It is multiplied by 100 to minimize the error. It is used
46 * for estimation of the power budget instead of using
47 * 'utilization' (which is 'busy_time / 'total_time').
48 * The 'res_util' range is from 100 to (power_table[state] * 100)
49 * for the corresponding 'state'.
50 * @capped_state: index to cooling state with in dynamic power budget
51 * @req_max_freq: PM QoS request for limiting the maximum frequency
52 * of the devfreq device.
54 struct devfreq_cooling_device {
56 struct thermal_cooling_device *cdev;
57 struct devfreq *devfreq;
58 unsigned long cooling_state;
61 size_t freq_table_size;
62 struct devfreq_cooling_power *power_ops;
65 struct dev_pm_qos_request req_max_freq;
68 static int devfreq_cooling_get_max_state(struct thermal_cooling_device *cdev,
71 struct devfreq_cooling_device *dfc = cdev->devdata;
73 *state = dfc->freq_table_size - 1;
78 static int devfreq_cooling_get_cur_state(struct thermal_cooling_device *cdev,
81 struct devfreq_cooling_device *dfc = cdev->devdata;
83 *state = dfc->cooling_state;
88 static int devfreq_cooling_set_cur_state(struct thermal_cooling_device *cdev,
91 struct devfreq_cooling_device *dfc = cdev->devdata;
92 struct devfreq *df = dfc->devfreq;
93 struct device *dev = df->dev.parent;
96 if (state == dfc->cooling_state)
99 dev_dbg(dev, "Setting cooling state %lu\n", state);
101 if (state >= dfc->freq_table_size)
104 freq = dfc->freq_table[state];
106 dev_pm_qos_update_request(&dfc->req_max_freq,
107 DIV_ROUND_UP(freq, HZ_PER_KHZ));
109 dfc->cooling_state = state;
115 * freq_get_state() - get the cooling state corresponding to a frequency
116 * @dfc: Pointer to devfreq cooling device
117 * @freq: frequency in Hz
119 * Return: the cooling state associated with the @freq, or
120 * THERMAL_CSTATE_INVALID if it wasn't found.
123 freq_get_state(struct devfreq_cooling_device *dfc, unsigned long freq)
127 for (i = 0; i < dfc->freq_table_size; i++) {
128 if (dfc->freq_table[i] == freq)
132 return THERMAL_CSTATE_INVALID;
135 static unsigned long get_voltage(struct devfreq *df, unsigned long freq)
137 struct device *dev = df->dev.parent;
138 unsigned long voltage;
139 struct dev_pm_opp *opp;
141 opp = dev_pm_opp_find_freq_exact(dev, freq, true);
142 if (PTR_ERR(opp) == -ERANGE)
143 opp = dev_pm_opp_find_freq_exact(dev, freq, false);
146 dev_err_ratelimited(dev, "Failed to find OPP for frequency %lu: %ld\n",
151 voltage = dev_pm_opp_get_voltage(opp) / 1000; /* mV */
155 dev_err_ratelimited(dev,
156 "Failed to get voltage for frequency %lu\n",
164 * get_static_power() - calculate the static power
165 * @dfc: Pointer to devfreq cooling device
166 * @freq: Frequency in Hz
168 * Calculate the static power in milliwatts using the supplied
169 * get_static_power(). The current voltage is calculated using the
170 * OPP library. If no get_static_power() was supplied, assume the
171 * static power is negligible.
174 get_static_power(struct devfreq_cooling_device *dfc, unsigned long freq)
176 struct devfreq *df = dfc->devfreq;
177 unsigned long voltage;
179 if (!dfc->power_ops->get_static_power)
182 voltage = get_voltage(df, freq);
187 return dfc->power_ops->get_static_power(df, voltage);
191 * get_dynamic_power - calculate the dynamic power
192 * @dfc: Pointer to devfreq cooling device
193 * @freq: Frequency in Hz
194 * @voltage: Voltage in millivolts
196 * Calculate the dynamic power in milliwatts consumed by the device at
197 * frequency @freq and voltage @voltage. If the get_dynamic_power()
198 * was supplied as part of the devfreq_cooling_power struct, then that
199 * function is used. Otherwise, a simple power model (Pdyn = Coeff *
200 * Voltage^2 * Frequency) is used.
203 get_dynamic_power(struct devfreq_cooling_device *dfc, unsigned long freq,
204 unsigned long voltage)
208 struct devfreq_cooling_power *dfc_power = dfc->power_ops;
210 if (dfc_power->get_dynamic_power)
211 return dfc_power->get_dynamic_power(dfc->devfreq, freq,
214 freq_mhz = freq / 1000000;
215 power = (u64)dfc_power->dyn_power_coeff * freq_mhz * voltage * voltage;
216 do_div(power, 1000000000);
222 static inline unsigned long get_total_power(struct devfreq_cooling_device *dfc,
224 unsigned long voltage)
226 return get_static_power(dfc, freq) + get_dynamic_power(dfc, freq,
231 static int devfreq_cooling_get_requested_power(struct thermal_cooling_device *cdev,
234 struct devfreq_cooling_device *dfc = cdev->devdata;
235 struct devfreq *df = dfc->devfreq;
236 struct devfreq_dev_status *status = &df->last_status;
238 unsigned long freq = status->current_frequency;
239 unsigned long voltage;
241 u32 static_power = 0;
244 state = freq_get_state(dfc, freq);
245 if (state == THERMAL_CSTATE_INVALID) {
250 if (dfc->power_ops->get_real_power) {
251 voltage = get_voltage(df, freq);
257 res = dfc->power_ops->get_real_power(df, power, freq, voltage);
259 state = dfc->capped_state;
260 dfc->res_util = dfc->power_table[state];
261 dfc->res_util *= SCALE_ERROR_MITIGATION;
264 dfc->res_util /= *power;
269 dyn_power = dfc->power_table[state];
271 /* Scale dynamic power for utilization */
272 dyn_power *= status->busy_time;
273 dyn_power /= status->total_time;
274 /* Get static power */
275 static_power = get_static_power(dfc, freq);
277 *power = dyn_power + static_power;
280 trace_thermal_power_devfreq_get_power(cdev, status, freq, dyn_power,
281 static_power, *power);
285 /* It is safe to set max in this case */
286 dfc->res_util = SCALE_ERROR_MITIGATION;
290 static int devfreq_cooling_state2power(struct thermal_cooling_device *cdev,
294 struct devfreq_cooling_device *dfc = cdev->devdata;
298 if (state >= dfc->freq_table_size)
301 freq = dfc->freq_table[state];
302 static_power = get_static_power(dfc, freq);
304 *power = dfc->power_table[state] + static_power;
308 static int devfreq_cooling_power2state(struct thermal_cooling_device *cdev,
309 u32 power, unsigned long *state)
311 struct devfreq_cooling_device *dfc = cdev->devdata;
312 struct devfreq *df = dfc->devfreq;
313 struct devfreq_dev_status *status = &df->last_status;
314 unsigned long freq = status->current_frequency;
315 unsigned long busy_time;
321 if (dfc->power_ops->get_real_power) {
322 /* Scale for resource utilization */
323 est_power = power * dfc->res_util;
324 est_power /= SCALE_ERROR_MITIGATION;
326 static_power = get_static_power(dfc, freq);
328 dyn_power = power - static_power;
329 dyn_power = dyn_power > 0 ? dyn_power : 0;
331 /* Scale dynamic power for utilization */
332 busy_time = status->busy_time ?: 1;
333 est_power = (dyn_power * status->total_time) / busy_time;
337 * Find the first cooling state that is within the power
338 * budget for dynamic power.
340 for (i = 0; i < dfc->freq_table_size - 1; i++)
341 if (est_power >= dfc->power_table[i])
345 dfc->capped_state = i;
346 trace_thermal_power_devfreq_limit(cdev, freq, *state, power);
350 static struct thermal_cooling_device_ops devfreq_cooling_ops = {
351 .get_max_state = devfreq_cooling_get_max_state,
352 .get_cur_state = devfreq_cooling_get_cur_state,
353 .set_cur_state = devfreq_cooling_set_cur_state,
357 * devfreq_cooling_gen_tables() - Generate power and freq tables.
358 * @dfc: Pointer to devfreq cooling device.
360 * Generate power and frequency tables: the power table hold the
361 * device's maximum power usage at each cooling state (OPP). The
362 * static and dynamic power using the appropriate voltage and
363 * frequency for the state, is acquired from the struct
364 * devfreq_cooling_power, and summed to make the maximum power draw.
366 * The frequency table holds the frequencies in descending order.
367 * That way its indexed by cooling device state.
369 * The tables are malloced, and pointers put in dfc. They must be
370 * freed when unregistering the devfreq cooling device.
372 * Return: 0 on success, negative error code on failure.
374 static int devfreq_cooling_gen_tables(struct devfreq_cooling_device *dfc)
376 struct devfreq *df = dfc->devfreq;
377 struct device *dev = df->dev.parent;
380 u32 *power_table = NULL;
384 num_opps = dev_pm_opp_get_opp_count(dev);
386 if (dfc->power_ops) {
387 power_table = kcalloc(num_opps, sizeof(*power_table),
393 freq_table = kcalloc(num_opps, sizeof(*freq_table),
397 goto free_power_table;
400 for (i = 0, freq = ULONG_MAX; i < num_opps; i++, freq--) {
401 unsigned long power, voltage;
402 struct dev_pm_opp *opp;
404 opp = dev_pm_opp_find_freq_floor(dev, &freq);
410 voltage = dev_pm_opp_get_voltage(opp) / 1000; /* mV */
413 if (dfc->power_ops) {
414 if (dfc->power_ops->get_real_power)
415 power = get_total_power(dfc, freq, voltage);
417 power = get_dynamic_power(dfc, freq, voltage);
419 dev_dbg(dev, "Power table: %lu MHz @ %lu mV: %lu = %lu mW\n",
420 freq / 1000000, voltage, power, power);
422 power_table[i] = power;
425 freq_table[i] = freq;
429 dfc->power_table = power_table;
431 dfc->freq_table = freq_table;
432 dfc->freq_table_size = num_opps;
445 * of_devfreq_cooling_register_power() - Register devfreq cooling device,
446 * with OF and power information.
447 * @np: Pointer to OF device_node.
448 * @df: Pointer to devfreq device.
449 * @dfc_power: Pointer to devfreq_cooling_power.
451 * Register a devfreq cooling device. The available OPPs must be
452 * registered on the device.
454 * If @dfc_power is provided, the cooling device is registered with the
455 * power extensions. For the power extensions to work correctly,
456 * devfreq should use the simple_ondemand governor, other governors
457 * are not currently supported.
459 struct thermal_cooling_device *
460 of_devfreq_cooling_register_power(struct device_node *np, struct devfreq *df,
461 struct devfreq_cooling_power *dfc_power)
463 struct thermal_cooling_device *cdev;
464 struct devfreq_cooling_device *dfc;
465 char dev_name[THERMAL_NAME_LENGTH];
468 dfc = kzalloc(sizeof(*dfc), GFP_KERNEL);
470 return ERR_PTR(-ENOMEM);
475 dfc->power_ops = dfc_power;
477 devfreq_cooling_ops.get_requested_power =
478 devfreq_cooling_get_requested_power;
479 devfreq_cooling_ops.state2power = devfreq_cooling_state2power;
480 devfreq_cooling_ops.power2state = devfreq_cooling_power2state;
483 err = devfreq_cooling_gen_tables(dfc);
487 err = dev_pm_qos_add_request(df->dev.parent, &dfc->req_max_freq,
488 DEV_PM_QOS_MAX_FREQUENCY,
489 PM_QOS_MAX_FREQUENCY_DEFAULT_VALUE);
493 err = ida_simple_get(&devfreq_ida, 0, 0, GFP_KERNEL);
498 snprintf(dev_name, sizeof(dev_name), "thermal-devfreq-%d", dfc->id);
500 cdev = thermal_of_cooling_device_register(np, dev_name, dfc,
501 &devfreq_cooling_ops);
504 dev_err(df->dev.parent,
505 "Failed to register devfreq cooling device (%d)\n",
515 ida_simple_remove(&devfreq_ida, dfc->id);
518 dev_pm_qos_remove_request(&dfc->req_max_freq);
521 kfree(dfc->power_table);
522 kfree(dfc->freq_table);
528 EXPORT_SYMBOL_GPL(of_devfreq_cooling_register_power);
531 * of_devfreq_cooling_register() - Register devfreq cooling device,
532 * with OF information.
533 * @np: Pointer to OF device_node.
534 * @df: Pointer to devfreq device.
536 struct thermal_cooling_device *
537 of_devfreq_cooling_register(struct device_node *np, struct devfreq *df)
539 return of_devfreq_cooling_register_power(np, df, NULL);
541 EXPORT_SYMBOL_GPL(of_devfreq_cooling_register);
544 * devfreq_cooling_register() - Register devfreq cooling device.
545 * @df: Pointer to devfreq device.
547 struct thermal_cooling_device *devfreq_cooling_register(struct devfreq *df)
549 return of_devfreq_cooling_register(NULL, df);
551 EXPORT_SYMBOL_GPL(devfreq_cooling_register);
554 * devfreq_cooling_unregister() - Unregister devfreq cooling device.
555 * @cdev: Pointer to devfreq cooling device to unregister.
557 void devfreq_cooling_unregister(struct thermal_cooling_device *cdev)
559 struct devfreq_cooling_device *dfc;
566 thermal_cooling_device_unregister(dfc->cdev);
567 ida_simple_remove(&devfreq_ida, dfc->id);
568 dev_pm_qos_remove_request(&dfc->req_max_freq);
569 kfree(dfc->power_table);
570 kfree(dfc->freq_table);
574 EXPORT_SYMBOL_GPL(devfreq_cooling_unregister);