// 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 #include #include #include #include #include #include /* * Mutex serializing the registrations of performance domains and letting * callbacks defined by drivers sleep. */ static DEFINE_MUTEX(em_pd_mutex); static void em_cpufreq_update_efficiencies(struct device *dev, struct em_perf_state *table); static void em_check_capacity_update(void); static void em_update_workfn(struct work_struct *work); static DECLARE_DELAYED_WORK(em_update_work, em_update_workfn); static bool _is_cpu_device(struct device *dev) { return (dev->bus == &cpu_subsys); } #ifdef CONFIG_DEBUG_FS static struct dentry *rootdir; struct em_dbg_info { struct em_perf_domain *pd; int ps_id; }; #define DEFINE_EM_DBG_SHOW(name, fname) \ static int em_debug_##fname##_show(struct seq_file *s, void *unused) \ { \ struct em_dbg_info *em_dbg = s->private; \ struct em_perf_state *table; \ unsigned long val; \ \ rcu_read_lock(); \ table = em_perf_state_from_pd(em_dbg->pd); \ val = table[em_dbg->ps_id].name; \ rcu_read_unlock(); \ \ seq_printf(s, "%lu\n", val); \ return 0; \ } \ DEFINE_SHOW_ATTRIBUTE(em_debug_##fname) DEFINE_EM_DBG_SHOW(frequency, frequency); DEFINE_EM_DBG_SHOW(power, power); DEFINE_EM_DBG_SHOW(cost, cost); DEFINE_EM_DBG_SHOW(performance, performance); DEFINE_EM_DBG_SHOW(flags, inefficiency); static void em_debug_create_ps(struct em_perf_domain *em_pd, struct em_dbg_info *em_dbg, int i, struct dentry *pd) { struct em_perf_state *table; unsigned long freq; struct dentry *d; char name[24]; em_dbg[i].pd = em_pd; em_dbg[i].ps_id = i; rcu_read_lock(); table = em_perf_state_from_pd(em_pd); freq = table[i].frequency; rcu_read_unlock(); snprintf(name, sizeof(name), "ps:%lu", freq); /* Create per-ps directory */ d = debugfs_create_dir(name, pd); debugfs_create_file("frequency", 0444, d, &em_dbg[i], &em_debug_frequency_fops); debugfs_create_file("power", 0444, d, &em_dbg[i], &em_debug_power_fops); debugfs_create_file("cost", 0444, d, &em_dbg[i], &em_debug_cost_fops); debugfs_create_file("performance", 0444, d, &em_dbg[i], &em_debug_performance_fops); debugfs_create_file("inefficient", 0444, d, &em_dbg[i], &em_debug_inefficiency_fops); } 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 em_dbg_info *em_dbg; 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); em_dbg = devm_kcalloc(dev, dev->em_pd->nr_perf_states, sizeof(*em_dbg), GFP_KERNEL); if (!em_dbg) return; /* 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, em_dbg, 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 void em_destroy_table_rcu(struct rcu_head *rp) { struct em_perf_table __rcu *table; table = container_of(rp, struct em_perf_table, rcu); kfree(table); } static void em_release_table_kref(struct kref *kref) { struct em_perf_table __rcu *table; /* It was the last owner of this table so we can free */ table = container_of(kref, struct em_perf_table, kref); call_rcu(&table->rcu, em_destroy_table_rcu); } /** * em_table_free() - Handles safe free of the EM table when needed * @table : EM table which is going to be freed * * No return values. */ void em_table_free(struct em_perf_table __rcu *table) { kref_put(&table->kref, em_release_table_kref); } /** * em_table_alloc() - Allocate a new EM table * @pd : EM performance domain for which this must be done * * Allocate a new EM table and initialize its kref to indicate that it * has a user. * Returns allocated table or NULL. */ struct em_perf_table __rcu *em_table_alloc(struct em_perf_domain *pd) { struct em_perf_table __rcu *table; int table_size; table_size = sizeof(struct em_perf_state) * pd->nr_perf_states; table = kzalloc(sizeof(*table) + table_size, GFP_KERNEL); if (!table) return NULL; kref_init(&table->kref); return table; } static void em_init_performance(struct device *dev, struct em_perf_domain *pd, struct em_perf_state *table, int nr_states) { u64 fmax, max_cap; int i, cpu; /* This is needed only for CPUs and EAS skip other devices */ if (!_is_cpu_device(dev)) return; cpu = cpumask_first(em_span_cpus(pd)); /* * Calculate the performance value for each frequency with * linear relationship. The final CPU capacity might not be ready at * boot time, but the EM will be updated a bit later with correct one. */ fmax = (u64) table[nr_states - 1].frequency; max_cap = (u64) arch_scale_cpu_capacity(cpu); for (i = 0; i < nr_states; i++) table[i].performance = div64_u64(max_cap * table[i].frequency, fmax); } static int em_compute_costs(struct device *dev, struct em_perf_state *table, struct em_data_callback *cb, int nr_states, unsigned long flags) { unsigned long prev_cost = ULONG_MAX; int i, ret; /* Compute the cost of each performance state. */ for (i = nr_states - 1; i >= 0; i--) { unsigned long power_res, cost; if ((flags & EM_PERF_DOMAIN_ARTIFICIAL) && cb->get_cost) { 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); return -EINVAL; } } else { /* increase resolution of 'cost' precision */ power_res = table[i].power * 10; cost = power_res / table[i].performance; } 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; } } return 0; } /** * em_dev_compute_costs() - Calculate cost values for new runtime EM table * @dev : Device for which the EM table is to be updated * @table : The new EM table that is going to get the costs calculated * @nr_states : Number of performance states * * Calculate the em_perf_state::cost values for new runtime EM table. The * values are used for EAS during task placement. It also calculates and sets * the efficiency flag for each performance state. When the function finish * successfully the EM table is ready to be updated and used by EAS. * * Return 0 on success or a proper error in case of failure. */ int em_dev_compute_costs(struct device *dev, struct em_perf_state *table, int nr_states) { return em_compute_costs(dev, table, NULL, nr_states, 0); } /** * em_dev_update_perf_domain() - Update runtime EM table for a device * @dev : Device for which the EM is to be updated * @new_table : The new EM table that is going to be used from now * * Update EM runtime modifiable table for the @dev using the provided @table. * * This function uses a mutex to serialize writers, so it must not be called * from a non-sleeping context. * * Return 0 on success or an error code on failure. */ int em_dev_update_perf_domain(struct device *dev, struct em_perf_table __rcu *new_table) { struct em_perf_table __rcu *old_table; struct em_perf_domain *pd; if (!dev) return -EINVAL; /* Serialize update/unregister or concurrent updates */ mutex_lock(&em_pd_mutex); if (!dev->em_pd) { mutex_unlock(&em_pd_mutex); return -EINVAL; } pd = dev->em_pd; kref_get(&new_table->kref); old_table = pd->em_table; rcu_assign_pointer(pd->em_table, new_table); em_cpufreq_update_efficiencies(dev, new_table->state); em_table_free(old_table); mutex_unlock(&em_pd_mutex); return 0; } EXPORT_SYMBOL_GPL(em_dev_update_perf_domain); static int em_create_perf_table(struct device *dev, struct em_perf_domain *pd, struct em_perf_state *table, struct em_data_callback *cb, unsigned long flags) { unsigned long power, freq, prev_freq = 0; int nr_states = pd->nr_perf_states; int i, ret; /* 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); return -EINVAL; } /* * 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); return -EINVAL; } /* * 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); return -EINVAL; } table[i].power = power; table[i].frequency = prev_freq = freq; } em_init_performance(dev, pd, table, nr_states); ret = em_compute_costs(dev, table, cb, nr_states, flags); if (ret) return -EINVAL; return 0; } 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_table __rcu *em_table; 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; } pd->nr_perf_states = nr_states; em_table = em_table_alloc(pd); if (!em_table) goto free_pd; ret = em_create_perf_table(dev, pd, em_table->state, cb, flags); if (ret) goto free_pd_table; rcu_assign_pointer(pd->em_table, em_table); 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; free_pd_table: kfree(em_table); free_pd: kfree(pd); return -EINVAL; } static void em_cpufreq_update_efficiencies(struct device *dev, struct em_perf_state *table) { struct em_perf_domain *pd = dev->em_pd; struct cpufreq_policy *policy; int found = 0; int i, cpu; if (!_is_cpu_device(dev)) return; /* Try to get a CPU which is active and in this PD */ cpu = cpumask_first_and(em_span_cpus(pd), cpu_active_mask); if (cpu >= nr_cpu_ids) { dev_warn(dev, "EM: No online CPU for CPUFreq policy\n"); return; } policy = cpufreq_cpu_get(cpu); if (!policy) { dev_warn(dev, "EM: Access to CPUFreq policy failed\n"); return; } 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; /* * EM only supports uW (exception is artificial EM). * Therefore, check and force the drivers to provide * power in uW. */ if (!microwatts && !(flags & EM_PERF_DOMAIN_ARTIFICIAL)) { dev_err(dev, "EM: only supports uW power values\n"); ret = -EINVAL; goto unlock; } ret = em_create_pd(dev, nr_states, cb, cpus, flags); if (ret) goto unlock; dev->em_pd->flags |= flags; em_cpufreq_update_efficiencies(dev, dev->em_pd->em_table->state); em_debug_create_pd(dev); dev_info(dev, "EM: created perf domain\n"); unlock: mutex_unlock(&em_pd_mutex); if (_is_cpu_device(dev)) em_check_capacity_update(); 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); em_table_free(dev->em_pd->em_table); kfree(dev->em_pd); dev->em_pd = NULL; mutex_unlock(&em_pd_mutex); } EXPORT_SYMBOL_GPL(em_dev_unregister_perf_domain); /* * Adjustment of CPU performance values after boot, when all CPUs capacites * are correctly calculated. */ static void em_adjust_new_capacity(struct device *dev, struct em_perf_domain *pd, u64 max_cap) { struct em_perf_table __rcu *em_table; struct em_perf_state *ps, *new_ps; int ret, ps_size; em_table = em_table_alloc(pd); if (!em_table) { dev_warn(dev, "EM: allocation failed\n"); return; } new_ps = em_table->state; rcu_read_lock(); ps = em_perf_state_from_pd(pd); /* Initialize data based on old table */ ps_size = sizeof(struct em_perf_state) * pd->nr_perf_states; memcpy(new_ps, ps, ps_size); rcu_read_unlock(); em_init_performance(dev, pd, new_ps, pd->nr_perf_states); ret = em_compute_costs(dev, new_ps, NULL, pd->nr_perf_states, pd->flags); if (ret) { dev_warn(dev, "EM: compute costs failed\n"); return; } ret = em_dev_update_perf_domain(dev, em_table); if (ret) dev_warn(dev, "EM: update failed %d\n", ret); /* * This is one-time-update, so give up the ownership in this updater. * The EM framework has incremented the usage counter and from now * will keep the reference (then free the memory when needed). */ em_table_free(em_table); } static void em_check_capacity_update(void) { cpumask_var_t cpu_done_mask; struct em_perf_state *table; struct em_perf_domain *pd; unsigned long cpu_capacity; int cpu; if (!zalloc_cpumask_var(&cpu_done_mask, GFP_KERNEL)) { pr_warn("no free memory\n"); return; } /* Check if CPUs capacity has changed than update EM */ for_each_possible_cpu(cpu) { struct cpufreq_policy *policy; unsigned long em_max_perf; struct device *dev; if (cpumask_test_cpu(cpu, cpu_done_mask)) continue; policy = cpufreq_cpu_get(cpu); if (!policy) { pr_debug("Accessing cpu%d policy failed\n", cpu); schedule_delayed_work(&em_update_work, msecs_to_jiffies(1000)); break; } cpufreq_cpu_put(policy); pd = em_cpu_get(cpu); if (!pd || em_is_artificial(pd)) continue; cpumask_or(cpu_done_mask, cpu_done_mask, em_span_cpus(pd)); cpu_capacity = arch_scale_cpu_capacity(cpu); rcu_read_lock(); table = em_perf_state_from_pd(pd); em_max_perf = table[pd->nr_perf_states - 1].performance; rcu_read_unlock(); /* * Check if the CPU capacity has been adjusted during boot * and trigger the update for new performance values. */ if (em_max_perf == cpu_capacity) continue; pr_debug("updating cpu%d cpu_cap=%lu old capacity=%lu\n", cpu, cpu_capacity, em_max_perf); dev = get_cpu_device(cpu); em_adjust_new_capacity(dev, pd, cpu_capacity); } free_cpumask_var(cpu_done_mask); } static void em_update_workfn(struct work_struct *work) { em_check_capacity_update(); }