--- /dev/null
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright 2020 Linaro Limited
+ *
+ * Author: Daniel Lezcano <daniel.lezcano@linaro.org>
+ *
+ * The DTPM CPU is based on the energy model. It hooks the CPU in the
+ * DTPM tree which in turns update the power number by propagating the
+ * power number from the CPU energy model information to the parents.
+ *
+ * The association between the power and the performance state, allows
+ * to set the power of the CPU at the OPP granularity.
+ *
+ * The CPU hotplug is supported and the power numbers will be updated
+ * if a CPU is hot plugged / unplugged.
+ */
+#include <linux/cpumask.h>
+#include <linux/cpufreq.h>
+#include <linux/cpuhotplug.h>
+#include <linux/dtpm.h>
+#include <linux/energy_model.h>
+#include <linux/pm_qos.h>
+#include <linux/slab.h>
+#include <linux/units.h>
+
+static struct dtpm *__parent;
+
+static DEFINE_PER_CPU(struct dtpm *, dtpm_per_cpu);
+
+struct dtpm_cpu {
+ struct freq_qos_request qos_req;
+ int cpu;
+};
+
+/*
+ * When a new CPU is inserted at hotplug or boot time, add the power
+ * contribution and update the dtpm tree.
+ */
+static int power_add(struct dtpm *dtpm, struct em_perf_domain *em)
+{
+ u64 power_min, power_max;
+
+ power_min = em->table[0].power;
+ power_min *= MICROWATT_PER_MILLIWATT;
+ power_min += dtpm->power_min;
+
+ power_max = em->table[em->nr_perf_states - 1].power;
+ power_max *= MICROWATT_PER_MILLIWATT;
+ power_max += dtpm->power_max;
+
+ return dtpm_update_power(dtpm, power_min, power_max);
+}
+
+/*
+ * When a CPU is unplugged, remove its power contribution from the
+ * dtpm tree.
+ */
+static int power_sub(struct dtpm *dtpm, struct em_perf_domain *em)
+{
+ u64 power_min, power_max;
+
+ power_min = em->table[0].power;
+ power_min *= MICROWATT_PER_MILLIWATT;
+ power_min = dtpm->power_min - power_min;
+
+ power_max = em->table[em->nr_perf_states - 1].power;
+ power_max *= MICROWATT_PER_MILLIWATT;
+ power_max = dtpm->power_max - power_max;
+
+ return dtpm_update_power(dtpm, power_min, power_max);
+}
+
+static u64 set_pd_power_limit(struct dtpm *dtpm, u64 power_limit)
+{
+ struct dtpm_cpu *dtpm_cpu = dtpm->private;
+ struct em_perf_domain *pd;
+ struct cpumask cpus;
+ unsigned long freq;
+ u64 power;
+ int i, nr_cpus;
+
+ pd = em_cpu_get(dtpm_cpu->cpu);
+
+ cpumask_and(&cpus, cpu_online_mask, to_cpumask(pd->cpus));
+
+ nr_cpus = cpumask_weight(&cpus);
+
+ for (i = 0; i < pd->nr_perf_states; i++) {
+
+ power = pd->table[i].power * MICROWATT_PER_MILLIWATT * nr_cpus;
+
+ if (power > power_limit)
+ break;
+ }
+
+ freq = pd->table[i - 1].frequency;
+
+ freq_qos_update_request(&dtpm_cpu->qos_req, freq);
+
+ power_limit = pd->table[i - 1].power *
+ MICROWATT_PER_MILLIWATT * nr_cpus;
+
+ return power_limit;
+}
+
+static u64 get_pd_power_uw(struct dtpm *dtpm)
+{
+ struct dtpm_cpu *dtpm_cpu = dtpm->private;
+ struct em_perf_domain *pd;
+ struct cpumask cpus;
+ unsigned long freq;
+ int i, nr_cpus;
+
+ pd = em_cpu_get(dtpm_cpu->cpu);
+ freq = cpufreq_quick_get(dtpm_cpu->cpu);
+ cpumask_and(&cpus, cpu_online_mask, to_cpumask(pd->cpus));
+ nr_cpus = cpumask_weight(&cpus);
+
+ for (i = 0; i < pd->nr_perf_states; i++) {
+
+ if (pd->table[i].frequency < freq)
+ continue;
+
+ return pd->table[i].power *
+ MICROWATT_PER_MILLIWATT * nr_cpus;
+ }
+
+ return 0;
+}
+
+static void pd_release(struct dtpm *dtpm)
+{
+ struct dtpm_cpu *dtpm_cpu = dtpm->private;
+
+ if (freq_qos_request_active(&dtpm_cpu->qos_req))
+ freq_qos_remove_request(&dtpm_cpu->qos_req);
+
+ kfree(dtpm_cpu);
+}
+
+static struct dtpm_ops dtpm_ops = {
+ .set_power_uw = set_pd_power_limit,
+ .get_power_uw = get_pd_power_uw,
+ .release = pd_release,
+};
+
+static int cpuhp_dtpm_cpu_offline(unsigned int cpu)
+{
+ struct cpufreq_policy *policy;
+ struct em_perf_domain *pd;
+ struct dtpm *dtpm;
+
+ policy = cpufreq_cpu_get(cpu);
+
+ if (!policy)
+ return 0;
+
+ pd = em_cpu_get(cpu);
+ if (!pd)
+ return -EINVAL;
+
+ dtpm = per_cpu(dtpm_per_cpu, cpu);
+
+ power_sub(dtpm, pd);
+
+ if (cpumask_weight(policy->cpus) != 1)
+ return 0;
+
+ for_each_cpu(cpu, policy->related_cpus)
+ per_cpu(dtpm_per_cpu, cpu) = NULL;
+
+ dtpm_unregister(dtpm);
+
+ return 0;
+}
+
+static int cpuhp_dtpm_cpu_online(unsigned int cpu)
+{
+ struct dtpm *dtpm;
+ struct dtpm_cpu *dtpm_cpu;
+ struct cpufreq_policy *policy;
+ struct em_perf_domain *pd;
+ char name[CPUFREQ_NAME_LEN];
+ int ret = -ENOMEM;
+
+ policy = cpufreq_cpu_get(cpu);
+
+ if (!policy)
+ return 0;
+
+ pd = em_cpu_get(cpu);
+ if (!pd)
+ return -EINVAL;
+
+ dtpm = per_cpu(dtpm_per_cpu, cpu);
+ if (dtpm)
+ return power_add(dtpm, pd);
+
+ dtpm = dtpm_alloc(&dtpm_ops);
+ if (!dtpm)
+ return -EINVAL;
+
+ dtpm_cpu = kzalloc(sizeof(dtpm_cpu), GFP_KERNEL);
+ if (!dtpm_cpu)
+ goto out_kfree_dtpm;
+
+ dtpm->private = dtpm_cpu;
+ dtpm_cpu->cpu = cpu;
+
+ for_each_cpu(cpu, policy->related_cpus)
+ per_cpu(dtpm_per_cpu, cpu) = dtpm;
+
+ sprintf(name, "cpu%d", dtpm_cpu->cpu);
+
+ ret = dtpm_register(name, dtpm, __parent);
+ if (ret)
+ goto out_kfree_dtpm_cpu;
+
+ ret = power_add(dtpm, pd);
+ if (ret)
+ goto out_dtpm_unregister;
+
+ ret = freq_qos_add_request(&policy->constraints,
+ &dtpm_cpu->qos_req, FREQ_QOS_MAX,
+ pd->table[pd->nr_perf_states - 1].frequency);
+ if (ret)
+ goto out_power_sub;
+
+ return 0;
+
+out_power_sub:
+ power_sub(dtpm, pd);
+
+out_dtpm_unregister:
+ dtpm_unregister(dtpm);
+ dtpm_cpu = NULL;
+ dtpm = NULL;
+
+out_kfree_dtpm_cpu:
+ for_each_cpu(cpu, policy->related_cpus)
+ per_cpu(dtpm_per_cpu, cpu) = NULL;
+ kfree(dtpm_cpu);
+
+out_kfree_dtpm:
+ kfree(dtpm);
+ return ret;
+}
+
+int dtpm_register_cpu(struct dtpm *parent)
+{
+ __parent = parent;
+
+ return cpuhp_setup_state(CPUHP_AP_DTPM_CPU_ONLINE,
+ "dtpm_cpu:online",
+ cpuhp_dtpm_cpu_online,
+ cpuhp_dtpm_cpu_offline);
+}
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