From patchwork Fri Apr 10 08:42:04 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Lukasz Luba X-Patchwork-Id: 11482869 X-Patchwork-Delegate: daniel.lezcano@linaro.org Return-Path: Received: from mail.kernel.org (pdx-korg-mail-1.web.codeaurora.org [172.30.200.123]) by pdx-korg-patchwork-2.web.codeaurora.org (Postfix) with ESMTP id 46EE61744 for ; Fri, 10 Apr 2020 08:43:16 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 175FC2084D for ; Fri, 10 Apr 2020 08:43:16 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1725991AbgDJInM (ORCPT ); Fri, 10 Apr 2020 04:43:12 -0400 Received: from foss.arm.com ([217.140.110.172]:58976 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725839AbgDJInL (ORCPT ); Fri, 10 Apr 2020 04:43:11 -0400 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id B79527FA; Fri, 10 Apr 2020 01:43:10 -0700 (PDT) Received: from e123648.arm.com (unknown [10.37.12.30]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id CFACC3F68F; Fri, 10 Apr 2020 01:43:00 -0700 (PDT) From: Lukasz Luba To: linux-kernel@vger.kernel.org, linux-pm@vger.kernel.org, linux-arm-kernel@lists.infradead.org, dri-devel@lists.freedesktop.org, linux-omap@vger.kernel.org, linux-mediatek@lists.infradead.org, linux-arm-msm@vger.kernel.org, linux-imx@nxp.com Cc: Dietmar.Eggemann@arm.com, cw00.choi@samsung.com, b.zolnierkie@samsung.com, rjw@rjwysocki.net, sudeep.holla@arm.com, viresh.kumar@linaro.org, nm@ti.com, sboyd@kernel.org, rui.zhang@intel.com, amit.kucheria@verdurent.com, daniel.lezcano@linaro.org, mingo@redhat.com, peterz@infradead.org, juri.lelli@redhat.com, vincent.guittot@linaro.org, rostedt@goodmis.org, qperret@google.com, bsegall@google.com, mgorman@suse.de, shawnguo@kernel.org, s.hauer@pengutronix.de, festevam@gmail.com, kernel@pengutronix.de, khilman@kernel.org, agross@kernel.org, bjorn.andersson@linaro.org, robh@kernel.org, matthias.bgg@gmail.com, steven.price@arm.com, tomeu.vizoso@collabora.com, alyssa.rosenzweig@collabora.com, airlied@linux.ie, daniel@ffwll.ch, liviu.dudau@arm.com, lorenzo.pieralisi@arm.com, lukasz.luba@arm.com, patrick.bellasi@matbug.net, orjan.eide@arm.com, rdunlap@infradead.org, mka@chromium.org Subject: [PATCH v6 04/10] PM / EM: add support for other devices than CPUs in Energy Model Date: Fri, 10 Apr 2020 09:42:04 +0100 Message-Id: <20200410084210.24932-5-lukasz.luba@arm.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20200410084210.24932-1-lukasz.luba@arm.com> References: <20200410084210.24932-1-lukasz.luba@arm.com> Sender: linux-pm-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-pm@vger.kernel.org Add support for other devices that CPUs. The registration function does not require a valid cpumask pointer and is ready to handle new devices. Some of the internal structures has been reorganized in order to keep consistent view (like removing per_cpu pd pointers). To track usage of the Energy Model structures, they are protected with kref. Signed-off-by: Lukasz Luba Reported-by: kbuild test robot --- include/linux/energy_model.h | 32 ++- kernel/power/energy_model.c | 433 +++++++++++++++++++++++++++++------ 2 files changed, 389 insertions(+), 76 deletions(-) diff --git a/include/linux/energy_model.h b/include/linux/energy_model.h index 7076cb22b247..f6b8077cc875 100644 --- a/include/linux/energy_model.h +++ b/include/linux/energy_model.h @@ -12,8 +12,10 @@ /** * em_perf_state - Performance state of a performance domain - * @frequency: The CPU frequency in KHz, for consistency with CPUFreq - * @power: The power consumed by 1 CPU at this level, in milli-watts + * @frequency: The frequency in KHz, for consistency with CPUFreq + * @power: The power consumed at this level, in milli-watts (by 1 CPU or + by a registered device). It can be a total power: static and + dynamic. * @cost: The cost coefficient associated with this level, used during * energy calculation. Equal to: power * max_frequency / frequency */ @@ -27,12 +29,15 @@ struct em_perf_state { * em_perf_domain - Performance domain * @table: List of performance states, in ascending order * @nr_perf_states: Number of performance states - * @cpus: Cpumask covering the CPUs of the domain + * @cpus: Cpumask covering the CPUs of the domain. It's here + * for performance reasons to avoid potential cache + * misses during energy calculations in the scheduler * - * A "performance domain" represents a group of CPUs whose performance is - * scaled together. All CPUs of a performance domain must have the same - * micro-architecture. Performance domains often have a 1-to-1 mapping with - * CPUFreq policies. + * In case of CPU device, a "performance domain" represents a group of CPUs + * whose performance is scaled together. All CPUs of a performance domain + * must have the same micro-architecture. Performance domains often have + * a 1-to-1 mapping with CPUFreq policies. In case of other devices the 'cpus' + * field is unused. */ struct em_perf_domain { struct em_perf_state *table; @@ -71,10 +76,13 @@ struct em_data_callback { #define EM_DATA_CB(_active_power_cb) { .active_power = &_active_power_cb } struct em_perf_domain *em_cpu_get(int cpu); +struct em_perf_domain *em_pd_get(struct device *dev); +void em_pd_put(struct device *dev); int em_register_perf_domain(cpumask_t *span, unsigned int nr_states, struct em_data_callback *cb); int em_dev_register_perf_domain(struct device *dev, unsigned int nr_states, struct em_data_callback *cb, cpumask_t *span); +void em_dev_unregister_perf_domain(struct device *dev); /** * em_pd_energy() - Estimates the energy consumed by the CPUs of a perf. domain @@ -184,10 +192,20 @@ int em_dev_register_perf_domain(struct device *dev, unsigned int nr_states, { return -EINVAL; } +static inline void em_dev_unregister_perf_domain(struct device *dev) +{ +} static inline struct em_perf_domain *em_cpu_get(int cpu) { return NULL; } +static inline struct em_perf_domain *em_pd_get(struct device *dev) +{ + return NULL; +} +static inline void em_pd_put(struct device *dev) +{ +} static inline unsigned long em_pd_energy(struct em_perf_domain *pd, unsigned long max_util, unsigned long sum_util) { diff --git a/kernel/power/energy_model.c b/kernel/power/energy_model.c index 5b8a1566526a..5967a21b56fc 100644 --- a/kernel/power/energy_model.c +++ b/kernel/power/energy_model.c @@ -2,8 +2,9 @@ /* * Energy Model of CPUs * - * Copyright (c) 2018, Arm ltd. + * 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 @@ -12,17 +13,46 @@ #include #include #include +#include +#include #include #include -/* Mapping of each CPU to the performance domain to which it belongs. */ -static DEFINE_PER_CPU(struct em_perf_domain *, em_data); +/** + * em_device - Performance domain wrapper for device + * @em_pd: Performance domain which carries the energy model + * @dev: Device for which this performance domain is set + * @id: Id of this performance domain + * @em_dev_list: List entry to connect all the devices perf. domain + * @debug_dir: Optional debug directory + * + * Internal structure. It contains a "performance domain" and the corresponding + * device. + */ +struct em_device { + struct em_perf_domain *em_pd; + struct device *dev; + int id; + struct kref kref; + struct list_head em_dev_list; +#ifdef CONFIG_DEBUG_FS + struct dentry *debug_dir; +#endif +}; +static DEFINE_IDA(em_dev_ida); /* * Mutex serializing the registrations of performance domains and letting * callbacks defined by drivers sleep. */ static DEFINE_MUTEX(em_pd_mutex); +/* List of devices' energy model, protected by 'em_pd_mutex' */ +static LIST_HEAD(em_pd_dev_list); + +static bool _is_cpu_device(struct device *dev) +{ + return (dev->bus == &cpu_subsys); +} #ifdef CONFIG_DEBUG_FS static struct dentry *rootdir; @@ -43,28 +73,74 @@ static void em_debug_create_ps(struct em_perf_state *ps, struct dentry *pd) static int em_debug_cpus_show(struct seq_file *s, void *unused) { - seq_printf(s, "%*pbl\n", cpumask_pr_args(to_cpumask(s->private))); + struct em_perf_domain *em_pd = s->private; + struct cpumask *mask = em_span_cpus(em_pd); + + seq_printf(s, "%*pbl\n", cpumask_pr_args(mask)); return 0; } DEFINE_SHOW_ATTRIBUTE(em_debug_cpus); -static void em_debug_create_pd(struct em_perf_domain *pd, int cpu) +static int em_debug_dev_show(struct seq_file *s, void *unused) { + struct em_device *em_dev = s->private; + const char *domain_name; + + domain_name = dev_name(em_dev->dev); + if (!domain_name) + domain_name = "unknown"; + + seq_printf(s, "%s\n", domain_name); + + return 0; +} +DEFINE_SHOW_ATTRIBUTE(em_debug_dev); + +static int em_debug_type_show(struct seq_file *s, void *unused) +{ + struct em_device *em_dev = s->private; + + if (_is_cpu_device(em_dev->dev)) + seq_puts(s, "EM cpufreq device\n"); + else + seq_puts(s, "EM devfreq device\n"); + + return 0; +} +DEFINE_SHOW_ATTRIBUTE(em_debug_type); + +static void em_debug_create_pd(struct em_device *em_dev) +{ + struct em_perf_domain *em_pd = em_dev->em_pd; struct dentry *d; char name[8]; int i; - snprintf(name, sizeof(name), "pd%d", cpu); + snprintf(name, sizeof(name), "pd%d", em_dev->id); /* Create the directory of the performance domain */ d = debugfs_create_dir(name, rootdir); - debugfs_create_file("cpus", 0444, d, pd->cpus, &em_debug_cpus_fops); + if (_is_cpu_device(em_dev->dev)) + debugfs_create_file("cpus", 0444, d, em_pd, + &em_debug_cpus_fops); + else + debugfs_create_file("dev_name", 0444, d, em_dev, + &em_debug_dev_fops); + + debugfs_create_file("type", 0444, d, em_dev, &em_debug_type_fops); /* Create a sub-directory for each performance state */ - for (i = 0; i < pd->nr_perf_states; i++) - em_debug_create_ps(&pd->table[i], d); + for (i = 0; i < em_pd->nr_perf_states; i++) + em_debug_create_ps(&em_pd->table[i], d); + + em_dev->debug_dir = d; +} + +static void em_debug_remove_pd(struct em_device *em_dev) +{ + debugfs_remove_recursive(em_dev->debug_dir); } static int __init em_debug_init(void) @@ -76,40 +152,34 @@ static int __init em_debug_init(void) } core_initcall(em_debug_init); #else /* CONFIG_DEBUG_FS */ -static void em_debug_create_pd(struct em_perf_domain *pd, int cpu) {} +static void em_debug_create_pd(struct em_device *em_dev) {} +static void em_debug_remove_pd(struct em_device *em_dev) {} #endif -static struct em_perf_domain * -em_create_pd(struct device *dev, int nr_states, struct em_data_callback *cb, - cpumask_t *span) + +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; - int i, ret, cpu = cpumask_first(span); struct em_perf_state *table; - struct em_perf_domain *pd; + int i, ret; u64 fmax; - if (!cb->active_power) - return NULL; - - pd = kzalloc(sizeof(*pd) + cpumask_size(), GFP_KERNEL); - if (!pd) - return NULL; - table = kcalloc(nr_states, sizeof(*table), GFP_KERNEL); if (!table) - goto free_pd; + 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 'cpu' above 'freq' and updates + * lowest performance state of 'dev' above 'freq' and updates * 'power' and 'freq' accordingly. */ ret = cb->active_power(&power, &freq, dev); if (ret) { - pr_err("pd%d: invalid perf. state: %d\n", cpu, ret); + dev_err(dev, "EM: invalid perf. state: %d\n", + ret); goto free_ps_table; } @@ -118,7 +188,8 @@ em_create_pd(struct device *dev, int nr_states, struct em_data_callback *cb, * higher performance states. */ if (freq <= prev_freq) { - pr_err("pd%d: non-increasing freq: %lu\n", cpu, freq); + dev_err(dev, "EM: non-increasing freq: %lu\n", + freq); goto free_ps_table; } @@ -127,7 +198,8 @@ em_create_pd(struct device *dev, int nr_states, struct em_data_callback *cb, * positive, in milli-watts and to fit into 16 bits. */ if (!power || power > EM_MAX_POWER) { - pr_err("pd%d: invalid power: %lu\n", cpu, power); + dev_err(dev, "EM: invalid power: %lu\n", + power); goto free_ps_table; } @@ -142,8 +214,8 @@ em_create_pd(struct device *dev, int nr_states, struct em_data_callback *cb, */ opp_eff = freq / power; if (opp_eff >= prev_opp_eff) - pr_warn("pd%d: hertz/watts ratio non-monotonically decreasing: em_perf_state %d >= em_perf_state%d\n", - cpu, i, i - 1); + 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; } @@ -156,30 +228,143 @@ em_create_pd(struct device *dev, int nr_states, struct em_data_callback *cb, pd->table = table; pd->nr_perf_states = nr_states; - cpumask_copy(to_cpumask(pd->cpus), span); - - em_debug_create_pd(pd, cpu); - return pd; + return 0; free_ps_table: kfree(table); -free_pd: - kfree(pd); + return -EINVAL; +} + +static struct em_perf_domain *em_create_pd(struct device *dev, int nr_states, + struct em_data_callback *cb, + cpumask_t *cpus) +{ + struct em_perf_domain *pd; + int ret; + + if (_is_cpu_device(dev)) { + pd = kzalloc(sizeof(*pd) + cpumask_size(), GFP_KERNEL); + if (!pd) + return NULL; + + cpumask_copy(em_span_cpus(pd), cpus); + } else { + pd = kzalloc(sizeof(*pd), GFP_KERNEL); + if (!pd) + return NULL; + } + + ret = em_create_perf_table(dev, pd, nr_states, cb); + if (ret) { + kfree(pd); + return NULL; + } + + return pd; +} + +static bool em_cpus_pd_exist(cpumask_t *span) +{ + struct em_device *em_dev; + + /* The em_pd_mutex should be held already. */ + if (list_empty(&em_pd_dev_list)) + return 0; + + list_for_each_entry(em_dev, &em_pd_dev_list, em_dev_list) { + if (!_is_cpu_device(em_dev->dev)) + continue; + + if (cpumask_intersects(span, em_span_cpus(em_dev->em_pd))) + return 1; + } + + return 0; +} + +static struct em_device *_em_dev_find_existing(struct device *dev) +{ + struct em_device *em_dev; + + /* The em_pd_mutex should be held already. */ + if (list_empty(&em_pd_dev_list)) + return NULL; + + list_for_each_entry(em_dev, &em_pd_dev_list, em_dev_list) + if (em_dev->dev == dev) + return em_dev; return NULL; } +/** + * 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) +{ + struct em_perf_domain *pd = NULL; + struct em_device *em_dev; + + if (IS_ERR_OR_NULL(dev)) + return NULL; + + if (_is_cpu_device(dev)) + return em_cpu_get(dev->id); + + mutex_lock(&em_pd_mutex); + + em_dev = _em_dev_find_existing(dev); + if (em_dev) { + kref_get(&em_dev->kref); + pd = em_dev->em_pd; + } + + mutex_unlock(&em_pd_mutex); + return 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 * - * Return: the performance domain to which 'cpu' belongs, or NULL if it doesn't + * This function is especially useful for subsystems which operate on CPU id, + * like topology setup code does. It simplifies code in those subsystems. + * + * Returns the performance domain to which 'cpu' belongs, or NULL if it doesn't * exist. */ struct em_perf_domain *em_cpu_get(int cpu) { - return READ_ONCE(per_cpu(em_data, cpu)); + struct em_device *em_dev; + + mutex_lock(&em_pd_mutex); + + if (list_empty(&em_pd_dev_list)) + goto unlock; + + list_for_each_entry(em_dev, &em_pd_dev_list, em_dev_list) { + if (!_is_cpu_device(em_dev->dev)) + continue; + + if (cpumask_test_cpu(cpu, em_span_cpus(em_dev->em_pd))) { + /* + * Don't increment kref here, we won't free the EM + * in CPU hotlpug. + */ + mutex_unlock(&em_pd_mutex); + return em_dev->em_pd; + } + } + +unlock: + mutex_unlock(&em_pd_mutex); + return NULL; } EXPORT_SYMBOL_GPL(em_cpu_get); @@ -188,7 +373,7 @@ EXPORT_SYMBOL_GPL(em_cpu_get); * @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 - * @span : Pointer to cpumask_t, which in case of a CPU device is + * @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. * @@ -201,13 +386,14 @@ EXPORT_SYMBOL_GPL(em_cpu_get); * Return 0 on success */ int em_dev_register_perf_domain(struct device *dev, unsigned int nr_states, - struct em_data_callback *cb, cpumask_t *span) + struct em_data_callback *cb, cpumask_t *cpus) { unsigned long cap, prev_cap = 0; struct em_perf_domain *pd; + struct em_device *em_dev; int cpu, ret = 0; - if (!dev || !span || !nr_states || !cb) + if (!dev || !nr_states || !cb) return -EINVAL; /* @@ -216,51 +402,104 @@ int em_dev_register_perf_domain(struct device *dev, unsigned int nr_states, */ mutex_lock(&em_pd_mutex); - for_each_cpu(cpu, span) { - /* Make sure we don't register again an existing domain. */ - if (READ_ONCE(per_cpu(em_data, cpu))) { - ret = -EEXIST; - goto unlock; + em_dev = _em_dev_find_existing(dev); + if (em_dev) { + mutex_unlock(&em_pd_mutex); + dev_dbg(dev, "EM: found exisiting pd%d\n", em_dev->id); + return -EEXIST; + } + + if (_is_cpu_device(dev)) { + if (!cpus) { + mutex_unlock(&em_pd_mutex); + dev_err(dev, "EM: invalid CPU mask\n"); + return -EINVAL; } - /* - * 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) { - pr_err("CPUs of %*pbl must have the same capacity\n", - cpumask_pr_args(span)); - ret = -EINVAL; - goto unlock; + /* Make sure we don't register domain for existing CPUs */ + if (em_cpus_pd_exist(cpus)) { + mutex_unlock(&em_pd_mutex); + return -EEXIST; + } + + for_each_cpu(cpu, cpus) { + /* + * 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)); + + mutex_unlock(&em_pd_mutex); + return -EINVAL; + } + prev_cap = cap; } - prev_cap = cap; } - /* Create the performance domain and add it to the Energy Model. */ - pd = em_create_pd(dev, nr_states, cb, span); + pd = em_create_pd(dev, nr_states, cb, cpus); if (!pd) { - ret = -EINVAL; - goto unlock; + mutex_unlock(&em_pd_mutex); + return -EINVAL; } - for_each_cpu(cpu, span) { - /* - * The per-cpu array can be read concurrently from em_cpu_get(). - * The barrier enforces the ordering needed to make sure readers - * can only access well formed em_perf_domain structs. - */ - smp_store_release(per_cpu_ptr(&em_data, cpu), pd); + em_dev = kzalloc(sizeof(struct em_device), GFP_KERNEL); + if (!em_dev) { + ret = -ENOMEM; + goto free_pd; } - pr_debug("Created perf domain %*pbl\n", cpumask_pr_args(span)); -unlock: + em_dev->id = ida_simple_get(&em_dev_ida, 0, 0, GFP_KERNEL); + if (em_dev->id < 0) { + ret = em_dev->id; + goto free_em_dev; + } + + em_dev->em_pd = pd; + em_dev->dev = dev; + + kref_init(&em_dev->kref); + list_add(&em_dev->em_dev_list, &em_pd_dev_list); + + em_debug_create_pd(em_dev); + dev_dbg(dev, "EM: created perf domain pd%d\n", em_dev->id); + mutex_unlock(&em_pd_mutex); + return 0; +free_em_dev: + kfree(em_dev); +free_pd: + kfree(pd->table); + kfree(pd); + + mutex_unlock(&em_pd_mutex); return ret; } EXPORT_SYMBOL_GPL(em_dev_register_perf_domain); +static void _em_release(struct kref *ref) +{ + struct em_device *em_dev = container_of(ref, struct em_device, kref); + struct em_perf_domain *pd = em_dev->em_pd; + + dev_dbg(em_dev->dev, "EM: freeing perf domain pd%d\n", em_dev->id); + + /* The em_pd_mutex is already locked. */ + list_del(&em_dev->em_dev_list); + + em_debug_remove_pd(em_dev); + + ida_simple_remove(&em_dev_ida, em_dev->id); + + kfree(pd->table); + kfree(pd); + kfree(em_dev); +} + /** * em_register_perf_domain() - Register the Energy Model of a performance domain * @span : Mask of CPUs in the performance domain @@ -285,3 +524,59 @@ int em_register_perf_domain(cpumask_t *span, unsigned int nr_states, return em_dev_register_perf_domain(cpu_dev, nr_states, cb, span); } EXPORT_SYMBOL_GPL(em_register_perf_domain); + +/** + * em_dev_unregister_perf_domain() - Unregister Energy Model (EM) for a device + * @dev : Device for which the EM is registered + * + * Try to unregister the EM for the specified device (it checks current + * reference counter). The EM for CPUs will not be freed. + */ +void em_dev_unregister_perf_domain(struct device *dev) +{ + struct em_device *em_dev, *tmp; + + if (IS_ERR_OR_NULL(dev)) + return; + + /* We don't support freeing CPU structures in hotplug */ + if (_is_cpu_device(dev)) { + dev_dbg_once(dev, "EM: the structures are not going to be removed\n"); + return; + } + + mutex_lock(&em_pd_mutex); + + if (list_empty(&em_pd_dev_list)) { + mutex_unlock(&em_pd_mutex); + return; + } + + list_for_each_entry_safe(em_dev, tmp, &em_pd_dev_list, em_dev_list) { + if (em_dev->dev == dev) { + kref_put(&em_dev->kref, _em_release); + break; + } + } + + mutex_unlock(&em_pd_mutex); +} +EXPORT_SYMBOL_GPL(em_dev_unregister_perf_domain); + +/** + * em_pd_put() - Decrement reference of the Energy Model (EM) for the device + * @dev : Device for which the EM is registered + * + * Decrement reference of the EM for the specified device. If it was the last + * reference then it will trigger cleaning. The EM for CPUs will not be freed, + * though. It goes in pair with em_pd_get() (which incremented a kref counter). + * This should be called when the code which called em_pd_get() has finished + * its work with EM structs and won't use them in future. Typical places where + * this should be called are e.g. driver unregister function or framework clean + * up functions. + */ +void em_pd_put(struct device *dev) +{ + em_dev_unregister_perf_domain(dev); +} +EXPORT_SYMBOL_GPL(em_pd_put);