// 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 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);
static struct em_perf_table __rcu *em_table_dup(struct em_perf_domain *pd)
{
struct em_perf_table __rcu *em_table;
struct em_perf_state *ps, *new_ps;
int ps_size;
em_table = em_table_alloc(pd);
if (!em_table)
return NULL;
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();
return em_table;
}
static int em_recalc_and_update(struct device *dev, struct em_perf_domain *pd,
struct em_perf_table __rcu *em_table)
{
int ret;
ret = em_compute_costs(dev, em_table->state, NULL, pd->nr_perf_states,
pd->flags);
if (ret)
goto free_em_table;
ret = em_dev_update_perf_domain(dev, em_table);
if (ret)
goto free_em_table;
/*
* 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).
*/
free_em_table:
em_table_free(em_table);
return ret;
}
/*
* 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;
em_table = em_table_dup(pd);
if (!em_table) {
dev_warn(dev, "EM: allocation failed\n");
return;
}
em_init_performance(dev, pd, em_table->state, pd->nr_perf_states);
em_recalc_and_update(dev, pd, 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();
}
/**
* em_dev_update_chip_binning() - Update Energy Model after the new voltage
* information is present in the OPPs.
* @dev : Device for which the Energy Model has to be updated.
*
* This function allows to update easily the EM with new values available in
* the OPP framework and DT. It can be used after the chip has been properly
* verified by device drivers and the voltages adjusted for the 'chip binning'.
*/
int em_dev_update_chip_binning(struct device *dev)
{
struct em_perf_table __rcu *em_table;
struct em_perf_domain *pd;
int i, ret;
if (IS_ERR_OR_NULL(dev))
return -EINVAL;
pd = em_pd_get(dev);
if (!pd) {
dev_warn(dev, "Couldn't find Energy Model\n");
return -EINVAL;
}
em_table = em_table_dup(pd);
if (!em_table) {
dev_warn(dev, "EM: allocation failed\n");
return -ENOMEM;
}
/* Update power values which might change due to new voltage in OPPs */
for (i = 0; i < pd->nr_perf_states; i++) {
unsigned long freq = em_table->state[i].frequency;
unsigned long power;
ret = dev_pm_opp_calc_power(dev, &power, &freq);
if (ret) {
em_table_free(em_table);
return ret;
}
em_table->state[i].power = power;
}
return em_recalc_and_update(dev, pd, em_table);
}
EXPORT_SYMBOL_GPL(em_dev_update_chip_binning);
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