kernel/power/energy_model.c - linux - Git at Google

 // SPDX-License-Identifier: GPL-2.0
 /*
  * Energy Model of devices
  *
  * Copyright (c) 2018-2020, 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/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);
 }

 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_units_show(struct seq_file *s, void *unused)
 {
 	struct em_perf_domain *pd = s->private;
 	char *units = pd->milliwatts ? "milliWatts" : "bogoWatts";

 	seq_printf(s, "%s\n", units);

 	return 0;
 }
 DEFINE_SHOW_ATTRIBUTE(em_debug_units);

 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("units", 0444, d, dev->em_pd, &em_debug_units_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)
 {
 	struct dentry *debug_dir;

 	debug_dir = debugfs_lookup(dev_name(dev), rootdir);
 	debugfs_remove_recursive(debug_dir);
 }

 static int __init em_debug_init(void)
 {
 	/* Create /sys/kernel/debug/energy_model directory */
 	rootdir = debugfs_create_dir("energy_model", NULL);

 	return 0;
 }
 core_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 opp_eff, prev_opp_eff = ULONG_MAX;
 	unsigned long power, freq, prev_freq = 0;
 	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(&power, &freq, dev);
 		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 to fit into 16 bits.
 		 */
 		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;

 		/*
 		 * The hertz/watts efficiency ratio should decrease as the
 		 * frequency grows on sane platforms. But this isn't always
 		 * true in practice so warn the user if a higher OPP is more
 		 * power efficient than a lower one.
 		 */
 		opp_eff = freq / power;
 		if (opp_eff >= prev_opp_eff)
 			dev_dbg(dev, "EM: hertz/watts ratio non-monotonically decreasing: em_perf_state %d >= em_perf_state%d\n",
 					i, i - 1);
 		prev_opp_eff = opp_eff;
 	}

 	/* Compute the cost of each performance state. */
 	fmax = (u64) table[nr_states - 1].frequency;
 	for (i = 0; i < nr_states; i++) {
 		table[i].cost = div64_u64(fmax * table[i].power,
 					  table[i].frequency);
 	}

 	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)
 {
 	struct em_perf_domain *pd;
 	struct device *cpu_dev;
 	int cpu, ret;

 	if (_is_cpu_device(dev)) {
 		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);
 	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;
 }

 /**
  * 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.
  * @milliwatts	: Flag indicating that the power values are in milliWatts 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 @milliwatts 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 milliwatts)
 {
 	unsigned long cap, prev_cap = 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;
 		}
 	}

 	ret = em_create_pd(dev, nr_states, cb, cpus);
 	if (ret)
 		goto unlock;

 	dev->em_pd->milliwatts = milliwatts;

 	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);
	// SPDX-License-Identifier: GPL-2.0
	/*
	* Energy Model of devices
	*
	* Copyright (c) 2018-2020, 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/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);
	}

	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_units_show(struct seq_file s, void unused)
	{
	struct em_perf_domain *pd = s->private;
	char *units = pd->milliwatts ? "milliWatts" : "bogoWatts";

	seq_printf(s, "%s\n", units);

	return 0;
	}
	DEFINE_SHOW_ATTRIBUTE(em_debug_units);

	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("units", 0444, d, dev->em_pd, &em_debug_units_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)
	{
	struct dentry *debug_dir;

	debug_dir = debugfs_lookup(dev_name(dev), rootdir);
	debugfs_remove_recursive(debug_dir);
	}

	static int __init em_debug_init(void)
	{
	/* Create /sys/kernel/debug/energy_model directory */
	rootdir = debugfs_create_dir("energy_model", NULL);

	return 0;
	}
	core_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 opp_eff, prev_opp_eff = ULONG_MAX;
	unsigned long power, freq, prev_freq = 0;
	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(&power, &freq, dev);
	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 to fit into 16 bits.
	*/
	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;

	/*
	* The hertz/watts efficiency ratio should decrease as the
	* frequency grows on sane platforms. But this isn't always
	* true in practice so warn the user if a higher OPP is more
	* power efficient than a lower one.
	*/
	opp_eff = freq / power;
	if (opp_eff >= prev_opp_eff)
	dev_dbg(dev, "EM: hertz/watts ratio non-monotonically decreasing: em_perf_state %d >= em_perf_state%d\n",
	i, i - 1);
	prev_opp_eff = opp_eff;
	}

	/* Compute the cost of each performance state. */
	fmax = (u64) table[nr_states - 1].frequency;
	for (i = 0; i < nr_states; i++) {
	table[i].cost = div64_u64(fmax * table[i].power,
	table[i].frequency);
	}

	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)
	{
	struct em_perf_domain *pd;
	struct device *cpu_dev;
	int cpu, ret;

	if (_is_cpu_device(dev)) {
	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);
	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;
	}

	/**
	* 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.
	* @milliwatts : Flag indicating that the power values are in milliWatts 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 @milliwatts 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 milliwatts)
	{
	unsigned long cap, prev_cap = 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;
	}
	}

	ret = em_create_pd(dev, nr_states, cb, cpus);
	if (ret)
	goto unlock;

	dev->em_pd->milliwatts = milliwatts;

	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);