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-rw-r--r--kernel/power/energy_model.c438
1 files changed, 438 insertions, 0 deletions
diff --git a/kernel/power/energy_model.c b/kernel/power/energy_model.c
new file mode 100644
index 0000000000..7b44f5b89f
--- /dev/null
+++ b/kernel/power/energy_model.c
@@ -0,0 +1,438 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Energy Model of devices
+ *
+ * Copyright (c) 2018-2021, Arm ltd.
+ * Written by: Quentin Perret, Arm ltd.
+ * Improvements provided by: Lukasz Luba, Arm ltd.
+ */
+
+#define pr_fmt(fmt) "energy_model: " fmt
+
+#include <linux/cpu.h>
+#include <linux/cpufreq.h>
+#include <linux/cpumask.h>
+#include <linux/debugfs.h>
+#include <linux/energy_model.h>
+#include <linux/sched/topology.h>
+#include <linux/slab.h>
+
+/*
+ * Mutex serializing the registrations of performance domains and letting
+ * callbacks defined by drivers sleep.
+ */
+static DEFINE_MUTEX(em_pd_mutex);
+
+static bool _is_cpu_device(struct device *dev)
+{
+ return (dev->bus == &cpu_subsys);
+}
+
+#ifdef CONFIG_DEBUG_FS
+static struct dentry *rootdir;
+
+static void em_debug_create_ps(struct em_perf_state *ps, struct dentry *pd)
+{
+ struct dentry *d;
+ char name[24];
+
+ snprintf(name, sizeof(name), "ps:%lu", ps->frequency);
+
+ /* Create per-ps directory */
+ d = debugfs_create_dir(name, pd);
+ debugfs_create_ulong("frequency", 0444, d, &ps->frequency);
+ debugfs_create_ulong("power", 0444, d, &ps->power);
+ debugfs_create_ulong("cost", 0444, d, &ps->cost);
+ debugfs_create_ulong("inefficient", 0444, d, &ps->flags);
+}
+
+static int em_debug_cpus_show(struct seq_file *s, void *unused)
+{
+ seq_printf(s, "%*pbl\n", cpumask_pr_args(to_cpumask(s->private)));
+
+ return 0;
+}
+DEFINE_SHOW_ATTRIBUTE(em_debug_cpus);
+
+static int em_debug_flags_show(struct seq_file *s, void *unused)
+{
+ struct em_perf_domain *pd = s->private;
+
+ seq_printf(s, "%#lx\n", pd->flags);
+
+ return 0;
+}
+DEFINE_SHOW_ATTRIBUTE(em_debug_flags);
+
+static void em_debug_create_pd(struct device *dev)
+{
+ struct dentry *d;
+ int i;
+
+ /* Create the directory of the performance domain */
+ d = debugfs_create_dir(dev_name(dev), rootdir);
+
+ if (_is_cpu_device(dev))
+ debugfs_create_file("cpus", 0444, d, dev->em_pd->cpus,
+ &em_debug_cpus_fops);
+
+ debugfs_create_file("flags", 0444, d, dev->em_pd,
+ &em_debug_flags_fops);
+
+ /* Create a sub-directory for each performance state */
+ for (i = 0; i < dev->em_pd->nr_perf_states; i++)
+ em_debug_create_ps(&dev->em_pd->table[i], d);
+
+}
+
+static void em_debug_remove_pd(struct device *dev)
+{
+ debugfs_lookup_and_remove(dev_name(dev), rootdir);
+}
+
+static int __init em_debug_init(void)
+{
+ /* Create /sys/kernel/debug/energy_model directory */
+ rootdir = debugfs_create_dir("energy_model", NULL);
+
+ return 0;
+}
+fs_initcall(em_debug_init);
+#else /* CONFIG_DEBUG_FS */
+static void em_debug_create_pd(struct device *dev) {}
+static void em_debug_remove_pd(struct device *dev) {}
+#endif
+
+static int em_create_perf_table(struct device *dev, struct em_perf_domain *pd,
+ int nr_states, struct em_data_callback *cb,
+ unsigned long flags)
+{
+ unsigned long power, freq, prev_freq = 0, prev_cost = ULONG_MAX;
+ struct em_perf_state *table;
+ int i, ret;
+ u64 fmax;
+
+ table = kcalloc(nr_states, sizeof(*table), GFP_KERNEL);
+ if (!table)
+ return -ENOMEM;
+
+ /* Build the list of performance states for this performance domain */
+ for (i = 0, freq = 0; i < nr_states; i++, freq++) {
+ /*
+ * active_power() is a driver callback which ceils 'freq' to
+ * lowest performance state of 'dev' above 'freq' and updates
+ * 'power' and 'freq' accordingly.
+ */
+ ret = cb->active_power(dev, &power, &freq);
+ if (ret) {
+ dev_err(dev, "EM: invalid perf. state: %d\n",
+ ret);
+ goto free_ps_table;
+ }
+
+ /*
+ * We expect the driver callback to increase the frequency for
+ * higher performance states.
+ */
+ if (freq <= prev_freq) {
+ dev_err(dev, "EM: non-increasing freq: %lu\n",
+ freq);
+ goto free_ps_table;
+ }
+
+ /*
+ * The power returned by active_state() is expected to be
+ * positive and be in range.
+ */
+ if (!power || power > EM_MAX_POWER) {
+ dev_err(dev, "EM: invalid power: %lu\n",
+ power);
+ goto free_ps_table;
+ }
+
+ table[i].power = power;
+ table[i].frequency = prev_freq = freq;
+ }
+
+ /* Compute the cost of each performance state. */
+ fmax = (u64) table[nr_states - 1].frequency;
+ for (i = nr_states - 1; i >= 0; i--) {
+ unsigned long power_res, cost;
+
+ if (flags & EM_PERF_DOMAIN_ARTIFICIAL) {
+ ret = cb->get_cost(dev, table[i].frequency, &cost);
+ if (ret || !cost || cost > EM_MAX_POWER) {
+ dev_err(dev, "EM: invalid cost %lu %d\n",
+ cost, ret);
+ goto free_ps_table;
+ }
+ } else {
+ power_res = table[i].power;
+ cost = div64_u64(fmax * power_res, table[i].frequency);
+ }
+
+ table[i].cost = cost;
+
+ if (table[i].cost >= prev_cost) {
+ table[i].flags = EM_PERF_STATE_INEFFICIENT;
+ dev_dbg(dev, "EM: OPP:%lu is inefficient\n",
+ table[i].frequency);
+ } else {
+ prev_cost = table[i].cost;
+ }
+ }
+
+ pd->table = table;
+ pd->nr_perf_states = nr_states;
+
+ return 0;
+
+free_ps_table:
+ kfree(table);
+ return -EINVAL;
+}
+
+static int em_create_pd(struct device *dev, int nr_states,
+ struct em_data_callback *cb, cpumask_t *cpus,
+ unsigned long flags)
+{
+ struct em_perf_domain *pd;
+ struct device *cpu_dev;
+ int cpu, ret, num_cpus;
+
+ if (_is_cpu_device(dev)) {
+ num_cpus = cpumask_weight(cpus);
+
+ /* Prevent max possible energy calculation to not overflow */
+ if (num_cpus > EM_MAX_NUM_CPUS) {
+ dev_err(dev, "EM: too many CPUs, overflow possible\n");
+ return -EINVAL;
+ }
+
+ pd = kzalloc(sizeof(*pd) + cpumask_size(), GFP_KERNEL);
+ if (!pd)
+ return -ENOMEM;
+
+ cpumask_copy(em_span_cpus(pd), cpus);
+ } else {
+ pd = kzalloc(sizeof(*pd), GFP_KERNEL);
+ if (!pd)
+ return -ENOMEM;
+ }
+
+ ret = em_create_perf_table(dev, pd, nr_states, cb, flags);
+ if (ret) {
+ kfree(pd);
+ return ret;
+ }
+
+ if (_is_cpu_device(dev))
+ for_each_cpu(cpu, cpus) {
+ cpu_dev = get_cpu_device(cpu);
+ cpu_dev->em_pd = pd;
+ }
+
+ dev->em_pd = pd;
+
+ return 0;
+}
+
+static void em_cpufreq_update_efficiencies(struct device *dev)
+{
+ struct em_perf_domain *pd = dev->em_pd;
+ struct em_perf_state *table;
+ struct cpufreq_policy *policy;
+ int found = 0;
+ int i;
+
+ if (!_is_cpu_device(dev) || !pd)
+ return;
+
+ policy = cpufreq_cpu_get(cpumask_first(em_span_cpus(pd)));
+ if (!policy) {
+ dev_warn(dev, "EM: Access to CPUFreq policy failed");
+ return;
+ }
+
+ table = pd->table;
+
+ for (i = 0; i < pd->nr_perf_states; i++) {
+ if (!(table[i].flags & EM_PERF_STATE_INEFFICIENT))
+ continue;
+
+ if (!cpufreq_table_set_inefficient(policy, table[i].frequency))
+ found++;
+ }
+
+ cpufreq_cpu_put(policy);
+
+ if (!found)
+ return;
+
+ /*
+ * Efficiencies have been installed in CPUFreq, inefficient frequencies
+ * will be skipped. The EM can do the same.
+ */
+ pd->flags |= EM_PERF_DOMAIN_SKIP_INEFFICIENCIES;
+}
+
+/**
+ * em_pd_get() - Return the performance domain for a device
+ * @dev : Device to find the performance domain for
+ *
+ * Returns the performance domain to which @dev belongs, or NULL if it doesn't
+ * exist.
+ */
+struct em_perf_domain *em_pd_get(struct device *dev)
+{
+ if (IS_ERR_OR_NULL(dev))
+ return NULL;
+
+ return dev->em_pd;
+}
+EXPORT_SYMBOL_GPL(em_pd_get);
+
+/**
+ * em_cpu_get() - Return the performance domain for a CPU
+ * @cpu : CPU to find the performance domain for
+ *
+ * Returns the performance domain to which @cpu belongs, or NULL if it doesn't
+ * exist.
+ */
+struct em_perf_domain *em_cpu_get(int cpu)
+{
+ struct device *cpu_dev;
+
+ cpu_dev = get_cpu_device(cpu);
+ if (!cpu_dev)
+ return NULL;
+
+ return em_pd_get(cpu_dev);
+}
+EXPORT_SYMBOL_GPL(em_cpu_get);
+
+/**
+ * em_dev_register_perf_domain() - Register the Energy Model (EM) for a device
+ * @dev : Device for which the EM is to register
+ * @nr_states : Number of performance states to register
+ * @cb : Callback functions providing the data of the Energy Model
+ * @cpus : Pointer to cpumask_t, which in case of a CPU device is
+ * obligatory. It can be taken from i.e. 'policy->cpus'. For other
+ * type of devices this should be set to NULL.
+ * @microwatts : Flag indicating that the power values are in micro-Watts or
+ * in some other scale. It must be set properly.
+ *
+ * Create Energy Model tables for a performance domain using the callbacks
+ * defined in cb.
+ *
+ * The @microwatts is important to set with correct value. Some kernel
+ * sub-systems might rely on this flag and check if all devices in the EM are
+ * using the same scale.
+ *
+ * If multiple clients register the same performance domain, all but the first
+ * registration will be ignored.
+ *
+ * Return 0 on success
+ */
+int em_dev_register_perf_domain(struct device *dev, unsigned int nr_states,
+ struct em_data_callback *cb, cpumask_t *cpus,
+ bool microwatts)
+{
+ unsigned long cap, prev_cap = 0;
+ unsigned long flags = 0;
+ int cpu, ret;
+
+ if (!dev || !nr_states || !cb)
+ return -EINVAL;
+
+ /*
+ * Use a mutex to serialize the registration of performance domains and
+ * let the driver-defined callback functions sleep.
+ */
+ mutex_lock(&em_pd_mutex);
+
+ if (dev->em_pd) {
+ ret = -EEXIST;
+ goto unlock;
+ }
+
+ if (_is_cpu_device(dev)) {
+ if (!cpus) {
+ dev_err(dev, "EM: invalid CPU mask\n");
+ ret = -EINVAL;
+ goto unlock;
+ }
+
+ for_each_cpu(cpu, cpus) {
+ if (em_cpu_get(cpu)) {
+ dev_err(dev, "EM: exists for CPU%d\n", cpu);
+ ret = -EEXIST;
+ goto unlock;
+ }
+ /*
+ * All CPUs of a domain must have the same
+ * micro-architecture since they all share the same
+ * table.
+ */
+ cap = arch_scale_cpu_capacity(cpu);
+ if (prev_cap && prev_cap != cap) {
+ dev_err(dev, "EM: CPUs of %*pbl must have the same capacity\n",
+ cpumask_pr_args(cpus));
+
+ ret = -EINVAL;
+ goto unlock;
+ }
+ prev_cap = cap;
+ }
+ }
+
+ if (microwatts)
+ flags |= EM_PERF_DOMAIN_MICROWATTS;
+ else if (cb->get_cost)
+ flags |= EM_PERF_DOMAIN_ARTIFICIAL;
+
+ ret = em_create_pd(dev, nr_states, cb, cpus, flags);
+ if (ret)
+ goto unlock;
+
+ dev->em_pd->flags |= flags;
+
+ em_cpufreq_update_efficiencies(dev);
+
+ em_debug_create_pd(dev);
+ dev_info(dev, "EM: created perf domain\n");
+
+unlock:
+ mutex_unlock(&em_pd_mutex);
+ return ret;
+}
+EXPORT_SYMBOL_GPL(em_dev_register_perf_domain);
+
+/**
+ * em_dev_unregister_perf_domain() - Unregister Energy Model (EM) for a device
+ * @dev : Device for which the EM is registered
+ *
+ * Unregister the EM for the specified @dev (but not a CPU device).
+ */
+void em_dev_unregister_perf_domain(struct device *dev)
+{
+ if (IS_ERR_OR_NULL(dev) || !dev->em_pd)
+ return;
+
+ if (_is_cpu_device(dev))
+ return;
+
+ /*
+ * The mutex separates all register/unregister requests and protects
+ * from potential clean-up/setup issues in the debugfs directories.
+ * The debugfs directory name is the same as device's name.
+ */
+ mutex_lock(&em_pd_mutex);
+ em_debug_remove_pd(dev);
+
+ kfree(dev->em_pd->table);
+ kfree(dev->em_pd);
+ dev->em_pd = NULL;
+ mutex_unlock(&em_pd_mutex);
+}
+EXPORT_SYMBOL_GPL(em_dev_unregister_perf_domain);