dtpm_cpu.c

  1// SPDX-License-Identifier: GPL-2.0-only
  2/*
  3 * Copyright 2020 Linaro Limited
  4 *
  5 * Author: Daniel Lezcano <daniel.lezcano@linaro.org>
  6 *
  7 * The DTPM CPU is based on the energy model. It hooks the CPU in the
  8 * DTPM tree which in turns update the power number by propagating the
  9 * power number from the CPU energy model information to the parents.
 10 *
 11 * The association between the power and the performance state, allows
 12 * to set the power of the CPU at the OPP granularity.
 13 *
 14 * The CPU hotplug is supported and the power numbers will be updated
 15 * if a CPU is hot plugged / unplugged.
 16 */
 17#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
 18
 19#include <linux/cpumask.h>
 20#include <linux/cpufreq.h>
 21#include <linux/cpuhotplug.h>
 22#include <linux/dtpm.h>
 23#include <linux/energy_model.h>
 24#include <linux/of.h>
 25#include <linux/pm_qos.h>
 26#include <linux/slab.h>
 27
 28struct dtpm_cpu {
 29	struct dtpm dtpm;
 30	struct freq_qos_request qos_req;
 31	int cpu;
 32};
 33
 34static DEFINE_PER_CPU(struct dtpm_cpu *, dtpm_per_cpu);
 35
 36static struct dtpm_cpu *to_dtpm_cpu(struct dtpm *dtpm)
 37{
 38	return container_of(dtpm, struct dtpm_cpu, dtpm);
 39}
 40
 41static u64 set_pd_power_limit(struct dtpm *dtpm, u64 power_limit)
 42{
 43	struct dtpm_cpu *dtpm_cpu = to_dtpm_cpu(dtpm);
 44	struct em_perf_domain *pd = em_cpu_get(dtpm_cpu->cpu);
 45	struct em_perf_state *table;
 46	unsigned long freq;
 47	u64 power;
 48	int i, nr_cpus;
 49
 50	nr_cpus = cpumask_weight_and(cpu_online_mask, to_cpumask(pd->cpus));
 51
 52	rcu_read_lock();
 53	table = em_perf_state_from_pd(pd);
 54	for (i = 0; i < pd->nr_perf_states; i++) {
 55
 56		power = table[i].power * nr_cpus;
 57
 58		if (power > power_limit)
 59			break;
 60	}
 61
 62	freq = table[i - 1].frequency;
 63	power_limit = table[i - 1].power * nr_cpus;
 64	rcu_read_unlock();
 65
 66	freq_qos_update_request(&dtpm_cpu->qos_req, freq);
 67
 68	return power_limit;
 69}
 70
 71static u64 scale_pd_power_uw(struct cpumask *pd_mask, u64 power)
 72{
 73	unsigned long max, sum_util = 0;
 74	int cpu;
 75
 76	/*
 77	 * The capacity is the same for all CPUs belonging to
 78	 * the same perf domain.
 79	 */
 80	max = arch_scale_cpu_capacity(cpumask_first(pd_mask));
 81
 82	for_each_cpu_and(cpu, pd_mask, cpu_online_mask)
 83		sum_util += sched_cpu_util(cpu);
 84
 85	return (power * ((sum_util << 10) / max)) >> 10;
 86}
 87
 88static u64 get_pd_power_uw(struct dtpm *dtpm)
 89{
 90	struct dtpm_cpu *dtpm_cpu = to_dtpm_cpu(dtpm);
 91	struct em_perf_state *table;
 92	struct em_perf_domain *pd;
 93	struct cpumask *pd_mask;
 94	unsigned long freq;
 95	u64 power = 0;
 96	int i;
 97
 98	pd = em_cpu_get(dtpm_cpu->cpu);
 99	if (!pd)
100		return 0;
101
102	pd_mask = em_span_cpus(pd);
103
104	freq = cpufreq_quick_get(dtpm_cpu->cpu);
105
106	rcu_read_lock();
107	table = em_perf_state_from_pd(pd);
108	for (i = 0; i < pd->nr_perf_states; i++) {
109
110		if (table[i].frequency < freq)
111			continue;
112
113		power = scale_pd_power_uw(pd_mask, table[i].power);
114		break;
115	}
116	rcu_read_unlock();
117
118	return power;
119}
120
121static int update_pd_power_uw(struct dtpm *dtpm)
122{
123	struct dtpm_cpu *dtpm_cpu = to_dtpm_cpu(dtpm);
124	struct em_perf_domain *em = em_cpu_get(dtpm_cpu->cpu);
125	struct em_perf_state *table;
126	int nr_cpus;
127
128	nr_cpus = cpumask_weight_and(cpu_online_mask, to_cpumask(em->cpus));
129
130	rcu_read_lock();
131	table = em_perf_state_from_pd(em);
132
133	dtpm->power_min = table[0].power;
134	dtpm->power_min *= nr_cpus;
135
136	dtpm->power_max = table[em->nr_perf_states - 1].power;
137	dtpm->power_max *= nr_cpus;
138
139	rcu_read_unlock();
140
141	return 0;
142}
143
144static void pd_release(struct dtpm *dtpm)
145{
146	struct dtpm_cpu *dtpm_cpu = to_dtpm_cpu(dtpm);
147	struct cpufreq_policy *policy;
148
149	if (freq_qos_request_active(&dtpm_cpu->qos_req))
150		freq_qos_remove_request(&dtpm_cpu->qos_req);
151
152	policy = cpufreq_cpu_get(dtpm_cpu->cpu);
153	if (policy) {
154		for_each_cpu(dtpm_cpu->cpu, policy->related_cpus)
155			per_cpu(dtpm_per_cpu, dtpm_cpu->cpu) = NULL;
156
157		cpufreq_cpu_put(policy);
158	}
159
160	kfree(dtpm_cpu);
161}
162
163static struct dtpm_ops dtpm_ops = {
164	.set_power_uw	 = set_pd_power_limit,
165	.get_power_uw	 = get_pd_power_uw,
166	.update_power_uw = update_pd_power_uw,
167	.release	 = pd_release,
168};
169
170static int cpuhp_dtpm_cpu_offline(unsigned int cpu)
171{
172	struct dtpm_cpu *dtpm_cpu;
173
174	dtpm_cpu = per_cpu(dtpm_per_cpu, cpu);
175	if (dtpm_cpu)
176		dtpm_update_power(&dtpm_cpu->dtpm);
177
178	return 0;
179}
180
181static int cpuhp_dtpm_cpu_online(unsigned int cpu)
182{
183	struct dtpm_cpu *dtpm_cpu;
184
185	dtpm_cpu = per_cpu(dtpm_per_cpu, cpu);
186	if (dtpm_cpu)
187		return dtpm_update_power(&dtpm_cpu->dtpm);
188
189	return 0;
190}
191
192static int __dtpm_cpu_setup(int cpu, struct dtpm *parent)
193{
194	struct dtpm_cpu *dtpm_cpu;
195	struct cpufreq_policy *policy;
196	struct em_perf_state *table;
197	struct em_perf_domain *pd;
198	char name[CPUFREQ_NAME_LEN];
199	int ret = -ENOMEM;
200
201	dtpm_cpu = per_cpu(dtpm_per_cpu, cpu);
202	if (dtpm_cpu)
203		return 0;
204
205	policy = cpufreq_cpu_get(cpu);
206	if (!policy)
207		return 0;
208
209	pd = em_cpu_get(cpu);
210	if (!pd || em_is_artificial(pd)) {
211		ret = -EINVAL;
212		goto release_policy;
213	}
214
215	dtpm_cpu = kzalloc(sizeof(*dtpm_cpu), GFP_KERNEL);
216	if (!dtpm_cpu) {
217		ret = -ENOMEM;
218		goto release_policy;
219	}
220
221	dtpm_init(&dtpm_cpu->dtpm, &dtpm_ops);
222	dtpm_cpu->cpu = cpu;
223
224	for_each_cpu(cpu, policy->related_cpus)
225		per_cpu(dtpm_per_cpu, cpu) = dtpm_cpu;
226
227	snprintf(name, sizeof(name), "cpu%d-cpufreq", dtpm_cpu->cpu);
228
229	ret = dtpm_register(name, &dtpm_cpu->dtpm, parent);
230	if (ret)
231		goto out_kfree_dtpm_cpu;
232
233	rcu_read_lock();
234	table = em_perf_state_from_pd(pd);
235	ret = freq_qos_add_request(&policy->constraints,
236				   &dtpm_cpu->qos_req, FREQ_QOS_MAX,
237				   table[pd->nr_perf_states - 1].frequency);
238	rcu_read_unlock();
239	if (ret < 0)
240		goto out_dtpm_unregister;
241
242	cpufreq_cpu_put(policy);
243	return 0;
244
245out_dtpm_unregister:
246	dtpm_unregister(&dtpm_cpu->dtpm);
247	dtpm_cpu = NULL;
248
249out_kfree_dtpm_cpu:
250	for_each_cpu(cpu, policy->related_cpus)
251		per_cpu(dtpm_per_cpu, cpu) = NULL;
252	kfree(dtpm_cpu);
253
254release_policy:
255	cpufreq_cpu_put(policy);
256	return ret;
257}
258
259static int dtpm_cpu_setup(struct dtpm *dtpm, struct device_node *np)
260{
261	int cpu;
262
263	cpu = of_cpu_node_to_id(np);
264	if (cpu < 0)
265		return 0;
266
267	return __dtpm_cpu_setup(cpu, dtpm);
268}
269
270static int dtpm_cpu_init(void)
271{
272	int ret;
273
274	/*
275	 * The callbacks at CPU hotplug time are calling
276	 * dtpm_update_power() which in turns calls update_pd_power().
277	 *
278	 * The function update_pd_power() uses the online mask to
279	 * figure out the power consumption limits.
280	 *
281	 * At CPUHP_AP_ONLINE_DYN, the CPU is present in the CPU
282	 * online mask when the cpuhp_dtpm_cpu_online function is
283	 * called, but the CPU is still in the online mask for the
284	 * tear down callback. So the power can not be updated when
285	 * the CPU is unplugged.
286	 *
287	 * At CPUHP_AP_DTPM_CPU_DEAD, the situation is the opposite as
288	 * above. The CPU online mask is not up to date when the CPU
289	 * is plugged in.
290	 *
291	 * For this reason, we need to call the online and offline
292	 * callbacks at different moments when the CPU online mask is
293	 * consistent with the power numbers we want to update.
294	 */
295	ret = cpuhp_setup_state(CPUHP_AP_DTPM_CPU_DEAD, "dtpm_cpu:offline",
296				NULL, cpuhp_dtpm_cpu_offline);
297	if (ret < 0)
298		return ret;
299
300	ret = cpuhp_setup_state(CPUHP_AP_ONLINE_DYN, "dtpm_cpu:online",
301				cpuhp_dtpm_cpu_online, NULL);
302	if (ret < 0)
303		return ret;
304
305	return 0;
306}
307
308static void dtpm_cpu_exit(void)
309{
310	cpuhp_remove_state_nocalls(CPUHP_AP_ONLINE_DYN);
311	cpuhp_remove_state_nocalls(CPUHP_AP_DTPM_CPU_DEAD);
312}
313
314struct dtpm_subsys_ops dtpm_cpu_ops = {
315	.name = KBUILD_MODNAME,
316	.init = dtpm_cpu_init,
317	.exit = dtpm_cpu_exit,
318	.setup = dtpm_cpu_setup,
319};