Adding upstream version 6.1.76.upstream/6.1.76

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 2953 insertions, 0 deletions

diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c
new file mode 100644
index 000000000..c8912756f
--- /dev/null
+++ b/drivers/cpufreq/cpufreq.c
@@ -0,0 +1,2953 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ *  linux/drivers/cpufreq/cpufreq.c
+ *
+ *  Copyright (C) 2001 Russell King
+ *            (C) 2002 - 2003 Dominik Brodowski <linux@brodo.de>
+ *            (C) 2013 Viresh Kumar <viresh.kumar@linaro.org>
+ *
+ *  Oct 2005 - Ashok Raj <ashok.raj@intel.com>
+ *	Added handling for CPU hotplug
+ *  Feb 2006 - Jacob Shin <jacob.shin@amd.com>
+ *	Fix handling for CPU hotplug -- affected CPUs
+ */
+
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+
+#include <linux/cpu.h>
+#include <linux/cpufreq.h>
+#include <linux/cpu_cooling.h>
+#include <linux/delay.h>
+#include <linux/device.h>
+#include <linux/init.h>
+#include <linux/kernel_stat.h>
+#include <linux/module.h>
+#include <linux/mutex.h>
+#include <linux/pm_qos.h>
+#include <linux/slab.h>
+#include <linux/suspend.h>
+#include <linux/syscore_ops.h>
+#include <linux/tick.h>
+#include <linux/units.h>
+#include <trace/events/power.h>
+
+static LIST_HEAD(cpufreq_policy_list);
+
+/* Macros to iterate over CPU policies */
+#define for_each_suitable_policy(__policy, __active)			 \
+	list_for_each_entry(__policy, &cpufreq_policy_list, policy_list) \
+		if ((__active) == !policy_is_inactive(__policy))
+
+#define for_each_active_policy(__policy)		\
+	for_each_suitable_policy(__policy, true)
+#define for_each_inactive_policy(__policy)		\
+	for_each_suitable_policy(__policy, false)
+
+/* Iterate over governors */
+static LIST_HEAD(cpufreq_governor_list);
+#define for_each_governor(__governor)				\
+	list_for_each_entry(__governor, &cpufreq_governor_list, governor_list)
+
+static char default_governor[CPUFREQ_NAME_LEN];
+
+/*
+ * The "cpufreq driver" - the arch- or hardware-dependent low
+ * level driver of CPUFreq support, and its spinlock. This lock
+ * also protects the cpufreq_cpu_data array.
+ */
+static struct cpufreq_driver *cpufreq_driver;
+static DEFINE_PER_CPU(struct cpufreq_policy *, cpufreq_cpu_data);
+static DEFINE_RWLOCK(cpufreq_driver_lock);
+
+static DEFINE_STATIC_KEY_FALSE(cpufreq_freq_invariance);
+bool cpufreq_supports_freq_invariance(void)
+{
+	return static_branch_likely(&cpufreq_freq_invariance);
+}
+
+/* Flag to suspend/resume CPUFreq governors */
+static bool cpufreq_suspended;
+
+static inline bool has_target(void)
+{
+	return cpufreq_driver->target_index || cpufreq_driver->target;
+}
+
+/* internal prototypes */
+static unsigned int __cpufreq_get(struct cpufreq_policy *policy);
+static int cpufreq_init_governor(struct cpufreq_policy *policy);
+static void cpufreq_exit_governor(struct cpufreq_policy *policy);
+static void cpufreq_governor_limits(struct cpufreq_policy *policy);
+static int cpufreq_set_policy(struct cpufreq_policy *policy,
+			      struct cpufreq_governor *new_gov,
+			      unsigned int new_pol);
+
+/*
+ * Two notifier lists: the "policy" list is involved in the
+ * validation process for a new CPU frequency policy; the
+ * "transition" list for kernel code that needs to handle
+ * changes to devices when the CPU clock speed changes.
+ * The mutex locks both lists.
+ */
+static BLOCKING_NOTIFIER_HEAD(cpufreq_policy_notifier_list);
+SRCU_NOTIFIER_HEAD_STATIC(cpufreq_transition_notifier_list);
+
+static int off __read_mostly;
+static int cpufreq_disabled(void)
+{
+	return off;
+}
+void disable_cpufreq(void)
+{
+	off = 1;
+}
+static DEFINE_MUTEX(cpufreq_governor_mutex);
+
+bool have_governor_per_policy(void)
+{
+	return !!(cpufreq_driver->flags & CPUFREQ_HAVE_GOVERNOR_PER_POLICY);
+}
+EXPORT_SYMBOL_GPL(have_governor_per_policy);
+
+static struct kobject *cpufreq_global_kobject;
+
+struct kobject *get_governor_parent_kobj(struct cpufreq_policy *policy)
+{
+	if (have_governor_per_policy())
+		return &policy->kobj;
+	else
+		return cpufreq_global_kobject;
+}
+EXPORT_SYMBOL_GPL(get_governor_parent_kobj);
+
+static inline u64 get_cpu_idle_time_jiffy(unsigned int cpu, u64 *wall)
+{
+	struct kernel_cpustat kcpustat;
+	u64 cur_wall_time;
+	u64 idle_time;
+	u64 busy_time;
+
+	cur_wall_time = jiffies64_to_nsecs(get_jiffies_64());
+
+	kcpustat_cpu_fetch(&kcpustat, cpu);
+
+	busy_time = kcpustat.cpustat[CPUTIME_USER];
+	busy_time += kcpustat.cpustat[CPUTIME_SYSTEM];
+	busy_time += kcpustat.cpustat[CPUTIME_IRQ];
+	busy_time += kcpustat.cpustat[CPUTIME_SOFTIRQ];
+	busy_time += kcpustat.cpustat[CPUTIME_STEAL];
+	busy_time += kcpustat.cpustat[CPUTIME_NICE];
+
+	idle_time = cur_wall_time - busy_time;
+	if (wall)
+		*wall = div_u64(cur_wall_time, NSEC_PER_USEC);
+
+	return div_u64(idle_time, NSEC_PER_USEC);
+}
+
+u64 get_cpu_idle_time(unsigned int cpu, u64 *wall, int io_busy)
+{
+	u64 idle_time = get_cpu_idle_time_us(cpu, io_busy ? wall : NULL);
+
+	if (idle_time == -1ULL)
+		return get_cpu_idle_time_jiffy(cpu, wall);
+	else if (!io_busy)
+		idle_time += get_cpu_iowait_time_us(cpu, wall);
+
+	return idle_time;
+}
+EXPORT_SYMBOL_GPL(get_cpu_idle_time);
+
+/*
+ * This is a generic cpufreq init() routine which can be used by cpufreq
+ * drivers of SMP systems. It will do following:
+ * - validate & show freq table passed
+ * - set policies transition latency
+ * - policy->cpus with all possible CPUs
+ */
+void cpufreq_generic_init(struct cpufreq_policy *policy,
+		struct cpufreq_frequency_table *table,
+		unsigned int transition_latency)
+{
+	policy->freq_table = table;
+	policy->cpuinfo.transition_latency = transition_latency;
+
+	/*
+	 * The driver only supports the SMP configuration where all processors
+	 * share the clock and voltage and clock.
+	 */
+	cpumask_setall(policy->cpus);
+}
+EXPORT_SYMBOL_GPL(cpufreq_generic_init);
+
+struct cpufreq_policy *cpufreq_cpu_get_raw(unsigned int cpu)
+{
+	struct cpufreq_policy *policy = per_cpu(cpufreq_cpu_data, cpu);
+
+	return policy && cpumask_test_cpu(cpu, policy->cpus) ? policy : NULL;
+}
+EXPORT_SYMBOL_GPL(cpufreq_cpu_get_raw);
+
+unsigned int cpufreq_generic_get(unsigned int cpu)
+{
+	struct cpufreq_policy *policy = cpufreq_cpu_get_raw(cpu);
+
+	if (!policy || IS_ERR(policy->clk)) {
+		pr_err("%s: No %s associated to cpu: %d\n",
+		       __func__, policy ? "clk" : "policy", cpu);
+		return 0;
+	}
+
+	return clk_get_rate(policy->clk) / 1000;
+}
+EXPORT_SYMBOL_GPL(cpufreq_generic_get);
+
+/**
+ * cpufreq_cpu_get - Return policy for a CPU and mark it as busy.
+ * @cpu: CPU to find the policy for.
+ *
+ * Call cpufreq_cpu_get_raw() to obtain a cpufreq policy for @cpu and increment
+ * the kobject reference counter of that policy.  Return a valid policy on
+ * success or NULL on failure.
+ *
+ * The policy returned by this function has to be released with the help of
+ * cpufreq_cpu_put() to balance its kobject reference counter properly.
+ */
+struct cpufreq_policy *cpufreq_cpu_get(unsigned int cpu)
+{
+	struct cpufreq_policy *policy = NULL;
+	unsigned long flags;
+
+	if (WARN_ON(cpu >= nr_cpu_ids))
+		return NULL;
+
+	/* get the cpufreq driver */
+	read_lock_irqsave(&cpufreq_driver_lock, flags);
+
+	if (cpufreq_driver) {
+		/* get the CPU */
+		policy = cpufreq_cpu_get_raw(cpu);
+		if (policy)
+			kobject_get(&policy->kobj);
+	}
+
+	read_unlock_irqrestore(&cpufreq_driver_lock, flags);
+
+	return policy;
+}
+EXPORT_SYMBOL_GPL(cpufreq_cpu_get);
+
+/**
+ * cpufreq_cpu_put - Decrement kobject usage counter for cpufreq policy.
+ * @policy: cpufreq policy returned by cpufreq_cpu_get().
+ */
+void cpufreq_cpu_put(struct cpufreq_policy *policy)
+{
+	kobject_put(&policy->kobj);
+}
+EXPORT_SYMBOL_GPL(cpufreq_cpu_put);
+
+/**
+ * cpufreq_cpu_release - Unlock a policy and decrement its usage counter.
+ * @policy: cpufreq policy returned by cpufreq_cpu_acquire().
+ */
+void cpufreq_cpu_release(struct cpufreq_policy *policy)
+{
+	if (WARN_ON(!policy))
+		return;
+
+	lockdep_assert_held(&policy->rwsem);
+
+	up_write(&policy->rwsem);
+
+	cpufreq_cpu_put(policy);
+}
+
+/**
+ * cpufreq_cpu_acquire - Find policy for a CPU, mark it as busy and lock it.
+ * @cpu: CPU to find the policy for.
+ *
+ * Call cpufreq_cpu_get() to get a reference on the cpufreq policy for @cpu and
+ * if the policy returned by it is not NULL, acquire its rwsem for writing.
+ * Return the policy if it is active or release it and return NULL otherwise.
+ *
+ * The policy returned by this function has to be released with the help of
+ * cpufreq_cpu_release() in order to release its rwsem and balance its usage
+ * counter properly.
+ */
+struct cpufreq_policy *cpufreq_cpu_acquire(unsigned int cpu)
+{
+	struct cpufreq_policy *policy = cpufreq_cpu_get(cpu);
+
+	if (!policy)
+		return NULL;
+
+	down_write(&policy->rwsem);
+
+	if (policy_is_inactive(policy)) {
+		cpufreq_cpu_release(policy);
+		return NULL;
+	}
+
+	return policy;
+}
+
+/*********************************************************************
+ *            EXTERNALLY AFFECTING FREQUENCY CHANGES                 *
+ *********************************************************************/
+
+/**
+ * adjust_jiffies - Adjust the system "loops_per_jiffy".
+ * @val: CPUFREQ_PRECHANGE or CPUFREQ_POSTCHANGE.
+ * @ci: Frequency change information.
+ *
+ * This function alters the system "loops_per_jiffy" for the clock
+ * speed change. Note that loops_per_jiffy cannot be updated on SMP
+ * systems as each CPU might be scaled differently. So, use the arch
+ * per-CPU loops_per_jiffy value wherever possible.
+ */
+static void adjust_jiffies(unsigned long val, struct cpufreq_freqs *ci)
+{
+#ifndef CONFIG_SMP
+	static unsigned long l_p_j_ref;
+	static unsigned int l_p_j_ref_freq;
+
+	if (ci->flags & CPUFREQ_CONST_LOOPS)
+		return;
+
+	if (!l_p_j_ref_freq) {
+		l_p_j_ref = loops_per_jiffy;
+		l_p_j_ref_freq = ci->old;
+		pr_debug("saving %lu as reference value for loops_per_jiffy; freq is %u kHz\n",
+			 l_p_j_ref, l_p_j_ref_freq);
+	}
+	if (val == CPUFREQ_POSTCHANGE && ci->old != ci->new) {
+		loops_per_jiffy = cpufreq_scale(l_p_j_ref, l_p_j_ref_freq,
+								ci->new);
+		pr_debug("scaling loops_per_jiffy to %lu for frequency %u kHz\n",
+			 loops_per_jiffy, ci->new);
+	}
+#endif
+}
+
+/**
+ * cpufreq_notify_transition - Notify frequency transition and adjust jiffies.
+ * @policy: cpufreq policy to enable fast frequency switching for.
+ * @freqs: contain details of the frequency update.
+ * @state: set to CPUFREQ_PRECHANGE or CPUFREQ_POSTCHANGE.
+ *
+ * This function calls the transition notifiers and adjust_jiffies().
+ *
+ * It is called twice on all CPU frequency changes that have external effects.
+ */
+static void cpufreq_notify_transition(struct cpufreq_policy *policy,
+				      struct cpufreq_freqs *freqs,
+				      unsigned int state)
+{
+	int cpu;
+
+	BUG_ON(irqs_disabled());
+
+	if (cpufreq_disabled())
+		return;
+
+	freqs->policy = policy;
+	freqs->flags = cpufreq_driver->flags;
+	pr_debug("notification %u of frequency transition to %u kHz\n",
+		 state, freqs->new);
+
+	switch (state) {
+	case CPUFREQ_PRECHANGE:
+		/*
+		 * Detect if the driver reported a value as "old frequency"
+		 * which is not equal to what the cpufreq core thinks is
+		 * "old frequency".
+		 */
+		if (policy->cur && policy->cur != freqs->old) {
+			pr_debug("Warning: CPU frequency is %u, cpufreq assumed %u kHz\n",
+				 freqs->old, policy->cur);
+			freqs->old = policy->cur;
+		}
+
+		srcu_notifier_call_chain(&cpufreq_transition_notifier_list,
+					 CPUFREQ_PRECHANGE, freqs);
+
+		adjust_jiffies(CPUFREQ_PRECHANGE, freqs);
+		break;
+
+	case CPUFREQ_POSTCHANGE:
+		adjust_jiffies(CPUFREQ_POSTCHANGE, freqs);
+		pr_debug("FREQ: %u - CPUs: %*pbl\n", freqs->new,
+			 cpumask_pr_args(policy->cpus));
+
+		for_each_cpu(cpu, policy->cpus)
+			trace_cpu_frequency(freqs->new, cpu);
+
+		srcu_notifier_call_chain(&cpufreq_transition_notifier_list,
+					 CPUFREQ_POSTCHANGE, freqs);
+
+		cpufreq_stats_record_transition(policy, freqs->new);
+		policy->cur = freqs->new;
+	}
+}
+
+/* Do post notifications when there are chances that transition has failed */
+static void cpufreq_notify_post_transition(struct cpufreq_policy *policy,
+		struct cpufreq_freqs *freqs, int transition_failed)
+{
+	cpufreq_notify_transition(policy, freqs, CPUFREQ_POSTCHANGE);
+	if (!transition_failed)
+		return;
+
+	swap(freqs->old, freqs->new);
+	cpufreq_notify_transition(policy, freqs, CPUFREQ_PRECHANGE);
+	cpufreq_notify_transition(policy, freqs, CPUFREQ_POSTCHANGE);
+}
+
+void cpufreq_freq_transition_begin(struct cpufreq_policy *policy,
+		struct cpufreq_freqs *freqs)
+{
+
+	/*
+	 * Catch double invocations of _begin() which lead to self-deadlock.
+	 * ASYNC_NOTIFICATION drivers are left out because the cpufreq core
+	 * doesn't invoke _begin() on their behalf, and hence the chances of
+	 * double invocations are very low. Moreover, there are scenarios
+	 * where these checks can emit false-positive warnings in these
+	 * drivers; so we avoid that by skipping them altogether.
+	 */
+	WARN_ON(!(cpufreq_driver->flags & CPUFREQ_ASYNC_NOTIFICATION)
+				&& current == policy->transition_task);
+
+wait:
+	wait_event(policy->transition_wait, !policy->transition_ongoing);
+
+	spin_lock(&policy->transition_lock);
+
+	if (unlikely(policy->transition_ongoing)) {
+		spin_unlock(&policy->transition_lock);
+		goto wait;
+	}
+
+	policy->transition_ongoing = true;
+	policy->transition_task = current;
+
+	spin_unlock(&policy->transition_lock);
+
+	cpufreq_notify_transition(policy, freqs, CPUFREQ_PRECHANGE);
+}
+EXPORT_SYMBOL_GPL(cpufreq_freq_transition_begin);
+
+void cpufreq_freq_transition_end(struct cpufreq_policy *policy,
+		struct cpufreq_freqs *freqs, int transition_failed)
+{
+	if (WARN_ON(!policy->transition_ongoing))
+		return;
+
+	cpufreq_notify_post_transition(policy, freqs, transition_failed);
+
+	arch_set_freq_scale(policy->related_cpus,
+			    policy->cur,
+			    policy->cpuinfo.max_freq);
+
+	spin_lock(&policy->transition_lock);
+	policy->transition_ongoing = false;
+	policy->transition_task = NULL;
+	spin_unlock(&policy->transition_lock);
+
+	wake_up(&policy->transition_wait);
+}
+EXPORT_SYMBOL_GPL(cpufreq_freq_transition_end);
+
+/*
+ * Fast frequency switching status count.  Positive means "enabled", negative
+ * means "disabled" and 0 means "not decided yet".
+ */
+static int cpufreq_fast_switch_count;
+static DEFINE_MUTEX(cpufreq_fast_switch_lock);
+
+static void cpufreq_list_transition_notifiers(void)
+{
+	struct notifier_block *nb;
+
+	pr_info("Registered transition notifiers:\n");
+
+	mutex_lock(&cpufreq_transition_notifier_list.mutex);
+
+	for (nb = cpufreq_transition_notifier_list.head; nb; nb = nb->next)
+		pr_info("%pS\n", nb->notifier_call);
+
+	mutex_unlock(&cpufreq_transition_notifier_list.mutex);
+}
+
+/**
+ * cpufreq_enable_fast_switch - Enable fast frequency switching for policy.
+ * @policy: cpufreq policy to enable fast frequency switching for.
+ *
+ * Try to enable fast frequency switching for @policy.
+ *
+ * The attempt will fail if there is at least one transition notifier registered
+ * at this point, as fast frequency switching is quite fundamentally at odds
+ * with transition notifiers.  Thus if successful, it will make registration of
+ * transition notifiers fail going forward.
+ */
+void cpufreq_enable_fast_switch(struct cpufreq_policy *policy)
+{
+	lockdep_assert_held(&policy->rwsem);
+
+	if (!policy->fast_switch_possible)
+		return;
+
+	mutex_lock(&cpufreq_fast_switch_lock);
+	if (cpufreq_fast_switch_count >= 0) {
+		cpufreq_fast_switch_count++;
+		policy->fast_switch_enabled = true;
+	} else {
+		pr_warn("CPU%u: Fast frequency switching not enabled\n",
+			policy->cpu);
+		cpufreq_list_transition_notifiers();
+	}
+	mutex_unlock(&cpufreq_fast_switch_lock);
+}
+EXPORT_SYMBOL_GPL(cpufreq_enable_fast_switch);
+
+/**
+ * cpufreq_disable_fast_switch - Disable fast frequency switching for policy.
+ * @policy: cpufreq policy to disable fast frequency switching for.
+ */
+void cpufreq_disable_fast_switch(struct cpufreq_policy *policy)
+{
+	mutex_lock(&cpufreq_fast_switch_lock);
+	if (policy->fast_switch_enabled) {
+		policy->fast_switch_enabled = false;
+		if (!WARN_ON(cpufreq_fast_switch_count <= 0))
+			cpufreq_fast_switch_count--;
+	}
+	mutex_unlock(&cpufreq_fast_switch_lock);
+}
+EXPORT_SYMBOL_GPL(cpufreq_disable_fast_switch);
+
+static unsigned int __resolve_freq(struct cpufreq_policy *policy,
+		unsigned int target_freq, unsigned int relation)
+{
+	unsigned int idx;
+
+	target_freq = clamp_val(target_freq, policy->min, policy->max);
+
+	if (!policy->freq_table)
+		return target_freq;
+
+	idx = cpufreq_frequency_table_target(policy, target_freq, relation);
+	policy->cached_resolved_idx = idx;
+	policy->cached_target_freq = target_freq;
+	return policy->freq_table[idx].frequency;
+}
+
+/**
+ * cpufreq_driver_resolve_freq - Map a target frequency to a driver-supported
+ * one.
+ * @policy: associated policy to interrogate
+ * @target_freq: target frequency to resolve.
+ *
+ * The target to driver frequency mapping is cached in the policy.
+ *
+ * Return: Lowest driver-supported frequency greater than or equal to the
+ * given target_freq, subject to policy (min/max) and driver limitations.
+ */
+unsigned int cpufreq_driver_resolve_freq(struct cpufreq_policy *policy,
+					 unsigned int target_freq)
+{
+	return __resolve_freq(policy, target_freq, CPUFREQ_RELATION_LE);
+}
+EXPORT_SYMBOL_GPL(cpufreq_driver_resolve_freq);
+
+unsigned int cpufreq_policy_transition_delay_us(struct cpufreq_policy *policy)
+{
+	unsigned int latency;
+
+	if (policy->transition_delay_us)
+		return policy->transition_delay_us;
+
+	latency = policy->cpuinfo.transition_latency / NSEC_PER_USEC;
+	if (latency) {
+		/*
+		 * For platforms that can change the frequency very fast (< 10
+		 * us), the above formula gives a decent transition delay. But
+		 * for platforms where transition_latency is in milliseconds, it
+		 * ends up giving unrealistic values.
+		 *
+		 * Cap the default transition delay to 10 ms, which seems to be
+		 * a reasonable amount of time after which we should reevaluate
+		 * the frequency.
+		 */
+		return min(latency * LATENCY_MULTIPLIER, (unsigned int)10000);
+	}
+
+	return LATENCY_MULTIPLIER;
+}
+EXPORT_SYMBOL_GPL(cpufreq_policy_transition_delay_us);
+
+/*********************************************************************
+ *                          SYSFS INTERFACE                          *
+ *********************************************************************/
+static ssize_t show_boost(struct kobject *kobj,
+			  struct kobj_attribute *attr, char *buf)
+{
+	return sprintf(buf, "%d\n", cpufreq_driver->boost_enabled);
+}
+
+static ssize_t store_boost(struct kobject *kobj, struct kobj_attribute *attr,
+			   const char *buf, size_t count)
+{
+	int ret, enable;
+
+	ret = sscanf(buf, "%d", &enable);
+	if (ret != 1 || enable < 0 || enable > 1)
+		return -EINVAL;
+
+	if (cpufreq_boost_trigger_state(enable)) {
+		pr_err("%s: Cannot %s BOOST!\n",
+		       __func__, enable ? "enable" : "disable");
+		return -EINVAL;
+	}
+
+	pr_debug("%s: cpufreq BOOST %s\n",
+		 __func__, enable ? "enabled" : "disabled");
+
+	return count;
+}
+define_one_global_rw(boost);
+
+static struct cpufreq_governor *find_governor(const char *str_governor)
+{
+	struct cpufreq_governor *t;
+
+	for_each_governor(t)
+		if (!strncasecmp(str_governor, t->name, CPUFREQ_NAME_LEN))
+			return t;
+
+	return NULL;
+}
+
+static struct cpufreq_governor *get_governor(const char *str_governor)
+{
+	struct cpufreq_governor *t;
+
+	mutex_lock(&cpufreq_governor_mutex);
+	t = find_governor(str_governor);
+	if (!t)
+		goto unlock;
+
+	if (!try_module_get(t->owner))
+		t = NULL;
+
+unlock:
+	mutex_unlock(&cpufreq_governor_mutex);
+
+	return t;
+}
+
+static unsigned int cpufreq_parse_policy(char *str_governor)
+{
+	if (!strncasecmp(str_governor, "performance", CPUFREQ_NAME_LEN))
+		return CPUFREQ_POLICY_PERFORMANCE;
+
+	if (!strncasecmp(str_governor, "powersave", CPUFREQ_NAME_LEN))
+		return CPUFREQ_POLICY_POWERSAVE;
+
+	return CPUFREQ_POLICY_UNKNOWN;
+}
+
+/**
+ * cpufreq_parse_governor - parse a governor string only for has_target()
+ * @str_governor: Governor name.
+ */
+static struct cpufreq_governor *cpufreq_parse_governor(char *str_governor)
+{
+	struct cpufreq_governor *t;
+
+	t = get_governor(str_governor);
+	if (t)
+		return t;
+
+	if (request_module("cpufreq_%s", str_governor))
+		return NULL;
+
+	return get_governor(str_governor);
+}
+
+/*
+ * cpufreq_per_cpu_attr_read() / show_##file_name() -
+ * print out cpufreq information
+ *
+ * Write out information from cpufreq_driver->policy[cpu]; object must be
+ * "unsigned int".
+ */
+
+#define show_one(file_name, object)			\
+static ssize_t show_##file_name				\
+(struct cpufreq_policy *policy, char *buf)		\
+{							\
+	return sprintf(buf, "%u\n", policy->object);	\
+}
+
+show_one(cpuinfo_min_freq, cpuinfo.min_freq);
+show_one(cpuinfo_max_freq, cpuinfo.max_freq);
+show_one(cpuinfo_transition_latency, cpuinfo.transition_latency);
+show_one(scaling_min_freq, min);
+show_one(scaling_max_freq, max);
+
+__weak unsigned int arch_freq_get_on_cpu(int cpu)
+{
+	return 0;
+}
+
+static ssize_t show_scaling_cur_freq(struct cpufreq_policy *policy, char *buf)
+{
+	ssize_t ret;
+	unsigned int freq;
+
+	freq = arch_freq_get_on_cpu(policy->cpu);
+	if (freq)
+		ret = sprintf(buf, "%u\n", freq);
+	else if (cpufreq_driver->setpolicy && cpufreq_driver->get)
+		ret = sprintf(buf, "%u\n", cpufreq_driver->get(policy->cpu));
+	else
+		ret = sprintf(buf, "%u\n", policy->cur);
+	return ret;
+}
+
+/*
+ * cpufreq_per_cpu_attr_write() / store_##file_name() - sysfs write access
+ */
+#define store_one(file_name, object)			\
+static ssize_t store_##file_name					\
+(struct cpufreq_policy *policy, const char *buf, size_t count)		\
+{									\
+	unsigned long val;						\
+	int ret;							\
+									\
+	ret = sscanf(buf, "%lu", &val);					\
+	if (ret != 1)							\
+		return -EINVAL;						\
+									\
+	ret = freq_qos_update_request(policy->object##_freq_req, val);\
+	return ret >= 0 ? count : ret;					\
+}
+
+store_one(scaling_min_freq, min);
+store_one(scaling_max_freq, max);
+
+/*
+ * show_cpuinfo_cur_freq - current CPU frequency as detected by hardware
+ */
+static ssize_t show_cpuinfo_cur_freq(struct cpufreq_policy *policy,
+					char *buf)
+{
+	unsigned int cur_freq = __cpufreq_get(policy);
+
+	if (cur_freq)
+		return sprintf(buf, "%u\n", cur_freq);
+
+	return sprintf(buf, "<unknown>\n");
+}
+
+/*
+ * show_scaling_governor - show the current policy for the specified CPU
+ */
+static ssize_t show_scaling_governor(struct cpufreq_policy *policy, char *buf)
+{
+	if (policy->policy == CPUFREQ_POLICY_POWERSAVE)
+		return sprintf(buf, "powersave\n");
+	else if (policy->policy == CPUFREQ_POLICY_PERFORMANCE)
+		return sprintf(buf, "performance\n");
+	else if (policy->governor)
+		return scnprintf(buf, CPUFREQ_NAME_PLEN, "%s\n",
+				policy->governor->name);
+	return -EINVAL;
+}
+
+/*
+ * store_scaling_governor - store policy for the specified CPU
+ */
+static ssize_t store_scaling_governor(struct cpufreq_policy *policy,
+					const char *buf, size_t count)
+{
+	char str_governor[16];
+	int ret;
+
+	ret = sscanf(buf, "%15s", str_governor);
+	if (ret != 1)
+		return -EINVAL;
+
+	if (cpufreq_driver->setpolicy) {
+		unsigned int new_pol;
+
+		new_pol = cpufreq_parse_policy(str_governor);
+		if (!new_pol)
+			return -EINVAL;
+
+		ret = cpufreq_set_policy(policy, NULL, new_pol);
+	} else {
+		struct cpufreq_governor *new_gov;
+
+		new_gov = cpufreq_parse_governor(str_governor);
+		if (!new_gov)
+			return -EINVAL;
+
+		ret = cpufreq_set_policy(policy, new_gov,
+					 CPUFREQ_POLICY_UNKNOWN);
+
+		module_put(new_gov->owner);
+	}
+
+	return ret ? ret : count;
+}
+
+/*
+ * show_scaling_driver - show the cpufreq driver currently loaded
+ */
+static ssize_t show_scaling_driver(struct cpufreq_policy *policy, char *buf)
+{
+	return scnprintf(buf, CPUFREQ_NAME_PLEN, "%s\n", cpufreq_driver->name);
+}
+
+/*
+ * show_scaling_available_governors - show the available CPUfreq governors
+ */
+static ssize_t show_scaling_available_governors(struct cpufreq_policy *policy,
+						char *buf)
+{
+	ssize_t i = 0;
+	struct cpufreq_governor *t;
+
+	if (!has_target()) {
+		i += sprintf(buf, "performance powersave");
+		goto out;
+	}
+
+	mutex_lock(&cpufreq_governor_mutex);
+	for_each_governor(t) {
+		if (i >= (ssize_t) ((PAGE_SIZE / sizeof(char))
+		    - (CPUFREQ_NAME_LEN + 2)))
+			break;
+		i += scnprintf(&buf[i], CPUFREQ_NAME_PLEN, "%s ", t->name);
+	}
+	mutex_unlock(&cpufreq_governor_mutex);
+out:
+	i += sprintf(&buf[i], "\n");
+	return i;
+}
+
+ssize_t cpufreq_show_cpus(const struct cpumask *mask, char *buf)
+{
+	ssize_t i = 0;
+	unsigned int cpu;
+
+	for_each_cpu(cpu, mask) {
+		i += scnprintf(&buf[i], (PAGE_SIZE - i - 2), "%u ", cpu);
+		if (i >= (PAGE_SIZE - 5))
+			break;
+	}
+
+	/* Remove the extra space at the end */
+	i--;
+
+	i += sprintf(&buf[i], "\n");
+	return i;
+}
+EXPORT_SYMBOL_GPL(cpufreq_show_cpus);
+
+/*
+ * show_related_cpus - show the CPUs affected by each transition even if
+ * hw coordination is in use
+ */
+static ssize_t show_related_cpus(struct cpufreq_policy *policy, char *buf)
+{
+	return cpufreq_show_cpus(policy->related_cpus, buf);
+}
+
+/*
+ * show_affected_cpus - show the CPUs affected by each transition
+ */
+static ssize_t show_affected_cpus(struct cpufreq_policy *policy, char *buf)
+{
+	return cpufreq_show_cpus(policy->cpus, buf);
+}
+
+static ssize_t store_scaling_setspeed(struct cpufreq_policy *policy,
+					const char *buf, size_t count)
+{
+	unsigned int freq = 0;
+	unsigned int ret;
+
+	if (!policy->governor || !policy->governor->store_setspeed)
+		return -EINVAL;
+
+	ret = sscanf(buf, "%u", &freq);
+	if (ret != 1)
+		return -EINVAL;
+
+	policy->governor->store_setspeed(policy, freq);
+
+	return count;
+}
+
+static ssize_t show_scaling_setspeed(struct cpufreq_policy *policy, char *buf)
+{
+	if (!policy->governor || !policy->governor->show_setspeed)
+		return sprintf(buf, "<unsupported>\n");
+
+	return policy->governor->show_setspeed(policy, buf);
+}
+
+/*
+ * show_bios_limit - show the current cpufreq HW/BIOS limitation
+ */
+static ssize_t show_bios_limit(struct cpufreq_policy *policy, char *buf)
+{
+	unsigned int limit;
+	int ret;
+	ret = cpufreq_driver->bios_limit(policy->cpu, &limit);
+	if (!ret)
+		return sprintf(buf, "%u\n", limit);
+	return sprintf(buf, "%u\n", policy->cpuinfo.max_freq);
+}
+
+cpufreq_freq_attr_ro_perm(cpuinfo_cur_freq, 0400);
+cpufreq_freq_attr_ro(cpuinfo_min_freq);
+cpufreq_freq_attr_ro(cpuinfo_max_freq);
+cpufreq_freq_attr_ro(cpuinfo_transition_latency);
+cpufreq_freq_attr_ro(scaling_available_governors);
+cpufreq_freq_attr_ro(scaling_driver);
+cpufreq_freq_attr_ro(scaling_cur_freq);
+cpufreq_freq_attr_ro(bios_limit);
+cpufreq_freq_attr_ro(related_cpus);
+cpufreq_freq_attr_ro(affected_cpus);
+cpufreq_freq_attr_rw(scaling_min_freq);
+cpufreq_freq_attr_rw(scaling_max_freq);
+cpufreq_freq_attr_rw(scaling_governor);
+cpufreq_freq_attr_rw(scaling_setspeed);
+
+static struct attribute *cpufreq_attrs[] = {
+	&cpuinfo_min_freq.attr,
+	&cpuinfo_max_freq.attr,
+	&cpuinfo_transition_latency.attr,
+	&scaling_min_freq.attr,
+	&scaling_max_freq.attr,
+	&affected_cpus.attr,
+	&related_cpus.attr,
+	&scaling_governor.attr,
+	&scaling_driver.attr,
+	&scaling_available_governors.attr,
+	&scaling_setspeed.attr,
+	NULL
+};
+ATTRIBUTE_GROUPS(cpufreq);
+
+#define to_policy(k) container_of(k, struct cpufreq_policy, kobj)
+#define to_attr(a) container_of(a, struct freq_attr, attr)
+
+static ssize_t show(struct kobject *kobj, struct attribute *attr, char *buf)
+{
+	struct cpufreq_policy *policy = to_policy(kobj);
+	struct freq_attr *fattr = to_attr(attr);
+	ssize_t ret = -EBUSY;
+
+	if (!fattr->show)
+		return -EIO;
+
+	down_read(&policy->rwsem);
+	if (likely(!policy_is_inactive(policy)))
+		ret = fattr->show(policy, buf);
+	up_read(&policy->rwsem);
+
+	return ret;
+}
+
+static ssize_t store(struct kobject *kobj, struct attribute *attr,
+		     const char *buf, size_t count)
+{
+	struct cpufreq_policy *policy = to_policy(kobj);
+	struct freq_attr *fattr = to_attr(attr);
+	ssize_t ret = -EBUSY;
+
+	if (!fattr->store)
+		return -EIO;
+
+	down_write(&policy->rwsem);
+	if (likely(!policy_is_inactive(policy)))
+		ret = fattr->store(policy, buf, count);
+	up_write(&policy->rwsem);
+
+	return ret;
+}
+
+static void cpufreq_sysfs_release(struct kobject *kobj)
+{
+	struct cpufreq_policy *policy = to_policy(kobj);
+	pr_debug("last reference is dropped\n");
+	complete(&policy->kobj_unregister);
+}
+
+static const struct sysfs_ops sysfs_ops = {
+	.show	= show,
+	.store	= store,
+};
+
+static struct kobj_type ktype_cpufreq = {
+	.sysfs_ops	= &sysfs_ops,
+	.default_groups	= cpufreq_groups,
+	.release	= cpufreq_sysfs_release,
+};
+
+static void add_cpu_dev_symlink(struct cpufreq_policy *policy, unsigned int cpu,
+				struct device *dev)
+{
+	if (unlikely(!dev))
+		return;
+
+	if (cpumask_test_and_set_cpu(cpu, policy->real_cpus))
+		return;
+
+	dev_dbg(dev, "%s: Adding symlink\n", __func__);
+	if (sysfs_create_link(&dev->kobj, &policy->kobj, "cpufreq"))
+		dev_err(dev, "cpufreq symlink creation failed\n");
+}
+
+static void remove_cpu_dev_symlink(struct cpufreq_policy *policy, int cpu,
+				   struct device *dev)
+{
+	dev_dbg(dev, "%s: Removing symlink\n", __func__);
+	sysfs_remove_link(&dev->kobj, "cpufreq");
+	cpumask_clear_cpu(cpu, policy->real_cpus);
+}
+
+static int cpufreq_add_dev_interface(struct cpufreq_policy *policy)
+{
+	struct freq_attr **drv_attr;
+	int ret = 0;
+
+	/* set up files for this cpu device */
+	drv_attr = cpufreq_driver->attr;
+	while (drv_attr && *drv_attr) {
+		ret = sysfs_create_file(&policy->kobj, &((*drv_attr)->attr));
+		if (ret)
+			return ret;
+		drv_attr++;
+	}
+	if (cpufreq_driver->get) {
+		ret = sysfs_create_file(&policy->kobj, &cpuinfo_cur_freq.attr);
+		if (ret)
+			return ret;
+	}
+
+	ret = sysfs_create_file(&policy->kobj, &scaling_cur_freq.attr);
+	if (ret)
+		return ret;
+
+	if (cpufreq_driver->bios_limit) {
+		ret = sysfs_create_file(&policy->kobj, &bios_limit.attr);
+		if (ret)
+			return ret;
+	}
+
+	return 0;
+}
+
+static int cpufreq_init_policy(struct cpufreq_policy *policy)
+{
+	struct cpufreq_governor *gov = NULL;
+	unsigned int pol = CPUFREQ_POLICY_UNKNOWN;
+	int ret;
+
+	if (has_target()) {
+		/* Update policy governor to the one used before hotplug. */
+		gov = get_governor(policy->last_governor);
+		if (gov) {
+			pr_debug("Restoring governor %s for cpu %d\n",
+				 gov->name, policy->cpu);
+		} else {
+			gov = get_governor(default_governor);
+		}
+
+		if (!gov) {
+			gov = cpufreq_default_governor();
+			__module_get(gov->owner);
+		}
+
+	} else {
+
+		/* Use the default policy if there is no last_policy. */
+		if (policy->last_policy) {
+			pol = policy->last_policy;
+		} else {
+			pol = cpufreq_parse_policy(default_governor);
+			/*
+			 * In case the default governor is neither "performance"
+			 * nor "powersave", fall back to the initial policy
+			 * value set by the driver.
+			 */
+			if (pol == CPUFREQ_POLICY_UNKNOWN)
+				pol = policy->policy;
+		}
+		if (pol != CPUFREQ_POLICY_PERFORMANCE &&
+		    pol != CPUFREQ_POLICY_POWERSAVE)
+			return -ENODATA;
+	}
+
+	ret = cpufreq_set_policy(policy, gov, pol);
+	if (gov)
+		module_put(gov->owner);
+
+	return ret;
+}
+
+static int cpufreq_add_policy_cpu(struct cpufreq_policy *policy, unsigned int cpu)
+{
+	int ret = 0;
+
+	/* Has this CPU been taken care of already? */
+	if (cpumask_test_cpu(cpu, policy->cpus))
+		return 0;
+
+	down_write(&policy->rwsem);
+	if (has_target())
+		cpufreq_stop_governor(policy);
+
+	cpumask_set_cpu(cpu, policy->cpus);
+
+	if (has_target()) {
+		ret = cpufreq_start_governor(policy);
+		if (ret)
+			pr_err("%s: Failed to start governor\n", __func__);
+	}
+	up_write(&policy->rwsem);
+	return ret;
+}
+
+void refresh_frequency_limits(struct cpufreq_policy *policy)
+{
+	if (!policy_is_inactive(policy)) {
+		pr_debug("updating policy for CPU %u\n", policy->cpu);
+
+		cpufreq_set_policy(policy, policy->governor, policy->policy);
+	}
+}
+EXPORT_SYMBOL(refresh_frequency_limits);
+
+static void handle_update(struct work_struct *work)
+{
+	struct cpufreq_policy *policy =
+		container_of(work, struct cpufreq_policy, update);
+
+	pr_debug("handle_update for cpu %u called\n", policy->cpu);
+	down_write(&policy->rwsem);
+	refresh_frequency_limits(policy);
+	up_write(&policy->rwsem);
+}
+
+static int cpufreq_notifier_min(struct notifier_block *nb, unsigned long freq,
+				void *data)
+{
+	struct cpufreq_policy *policy = container_of(nb, struct cpufreq_policy, nb_min);
+
+	schedule_work(&policy->update);
+	return 0;
+}
+
+static int cpufreq_notifier_max(struct notifier_block *nb, unsigned long freq,
+				void *data)
+{
+	struct cpufreq_policy *policy = container_of(nb, struct cpufreq_policy, nb_max);
+
+	schedule_work(&policy->update);
+	return 0;
+}
+
+static void cpufreq_policy_put_kobj(struct cpufreq_policy *policy)
+{
+	struct kobject *kobj;
+	struct completion *cmp;
+
+	down_write(&policy->rwsem);
+	cpufreq_stats_free_table(policy);
+	kobj = &policy->kobj;
+	cmp = &policy->kobj_unregister;
+	up_write(&policy->rwsem);
+	kobject_put(kobj);
+
+	/*
+	 * We need to make sure that the underlying kobj is
+	 * actually not referenced anymore by anybody before we
+	 * proceed with unloading.
+	 */
+	pr_debug("waiting for dropping of refcount\n");
+	wait_for_completion(cmp);
+	pr_debug("wait complete\n");
+}
+
+static struct cpufreq_policy *cpufreq_policy_alloc(unsigned int cpu)
+{
+	struct cpufreq_policy *policy;
+	struct device *dev = get_cpu_device(cpu);
+	int ret;
+
+	if (!dev)
+		return NULL;
+
+	policy = kzalloc(sizeof(*policy), GFP_KERNEL);
+	if (!policy)
+		return NULL;
+
+	if (!alloc_cpumask_var(&policy->cpus, GFP_KERNEL))
+		goto err_free_policy;
+
+	if (!zalloc_cpumask_var(&policy->related_cpus, GFP_KERNEL))
+		goto err_free_cpumask;
+
+	if (!zalloc_cpumask_var(&policy->real_cpus, GFP_KERNEL))
+		goto err_free_rcpumask;
+
+	init_completion(&policy->kobj_unregister);
+	ret = kobject_init_and_add(&policy->kobj, &ktype_cpufreq,
+				   cpufreq_global_kobject, "policy%u", cpu);
+	if (ret) {
+		dev_err(dev, "%s: failed to init policy->kobj: %d\n", __func__, ret);
+		/*
+		 * The entire policy object will be freed below, but the extra
+		 * memory allocated for the kobject name needs to be freed by
+		 * releasing the kobject.
+		 */
+		kobject_put(&policy->kobj);
+		goto err_free_real_cpus;
+	}
+
+	freq_constraints_init(&policy->constraints);
+
+	policy->nb_min.notifier_call = cpufreq_notifier_min;
+	policy->nb_max.notifier_call = cpufreq_notifier_max;
+
+	ret = freq_qos_add_notifier(&policy->constraints, FREQ_QOS_MIN,
+				    &policy->nb_min);
+	if (ret) {
+		dev_err(dev, "Failed to register MIN QoS notifier: %d (%*pbl)\n",
+			ret, cpumask_pr_args(policy->cpus));
+		goto err_kobj_remove;
+	}
+
+	ret = freq_qos_add_notifier(&policy->constraints, FREQ_QOS_MAX,
+				    &policy->nb_max);
+	if (ret) {
+		dev_err(dev, "Failed to register MAX QoS notifier: %d (%*pbl)\n",
+			ret, cpumask_pr_args(policy->cpus));
+		goto err_min_qos_notifier;
+	}
+
+	INIT_LIST_HEAD(&policy->policy_list);
+	init_rwsem(&policy->rwsem);
+	spin_lock_init(&policy->transition_lock);
+	init_waitqueue_head(&policy->transition_wait);
+	INIT_WORK(&policy->update, handle_update);
+
+	policy->cpu = cpu;
+	return policy;
+
+err_min_qos_notifier:
+	freq_qos_remove_notifier(&policy->constraints, FREQ_QOS_MIN,
+				 &policy->nb_min);
+err_kobj_remove:
+	cpufreq_policy_put_kobj(policy);
+err_free_real_cpus:
+	free_cpumask_var(policy->real_cpus);
+err_free_rcpumask:
+	free_cpumask_var(policy->related_cpus);
+err_free_cpumask:
+	free_cpumask_var(policy->cpus);
+err_free_policy:
+	kfree(policy);
+
+	return NULL;
+}
+
+static void cpufreq_policy_free(struct cpufreq_policy *policy)
+{
+	unsigned long flags;
+	int cpu;
+
+	/*
+	 * The callers must ensure the policy is inactive by now, to avoid any
+	 * races with show()/store() callbacks.
+	 */
+	if (unlikely(!policy_is_inactive(policy)))
+		pr_warn("%s: Freeing active policy\n", __func__);
+
+	/* Remove policy from list */
+	write_lock_irqsave(&cpufreq_driver_lock, flags);
+	list_del(&policy->policy_list);
+
+	for_each_cpu(cpu, policy->related_cpus)
+		per_cpu(cpufreq_cpu_data, cpu) = NULL;
+	write_unlock_irqrestore(&cpufreq_driver_lock, flags);
+
+	freq_qos_remove_notifier(&policy->constraints, FREQ_QOS_MAX,
+				 &policy->nb_max);
+	freq_qos_remove_notifier(&policy->constraints, FREQ_QOS_MIN,
+				 &policy->nb_min);
+
+	/* Cancel any pending policy->update work before freeing the policy. */
+	cancel_work_sync(&policy->update);
+
+	if (policy->max_freq_req) {
+		/*
+		 * Remove max_freq_req after sending CPUFREQ_REMOVE_POLICY
+		 * notification, since CPUFREQ_CREATE_POLICY notification was
+		 * sent after adding max_freq_req earlier.
+		 */
+		blocking_notifier_call_chain(&cpufreq_policy_notifier_list,
+					     CPUFREQ_REMOVE_POLICY, policy);
+		freq_qos_remove_request(policy->max_freq_req);
+	}
+
+	freq_qos_remove_request(policy->min_freq_req);
+	kfree(policy->min_freq_req);
+
+	cpufreq_policy_put_kobj(policy);
+	free_cpumask_var(policy->real_cpus);
+	free_cpumask_var(policy->related_cpus);
+	free_cpumask_var(policy->cpus);
+	kfree(policy);
+}
+
+static int cpufreq_online(unsigned int cpu)
+{
+	struct cpufreq_policy *policy;
+	bool new_policy;
+	unsigned long flags;
+	unsigned int j;
+	int ret;
+
+	pr_debug("%s: bringing CPU%u online\n", __func__, cpu);
+
+	/* Check if this CPU already has a policy to manage it */
+	policy = per_cpu(cpufreq_cpu_data, cpu);
+	if (policy) {
+		WARN_ON(!cpumask_test_cpu(cpu, policy->related_cpus));
+		if (!policy_is_inactive(policy))
+			return cpufreq_add_policy_cpu(policy, cpu);
+
+		/* This is the only online CPU for the policy.  Start over. */
+		new_policy = false;
+		down_write(&policy->rwsem);
+		policy->cpu = cpu;
+		policy->governor = NULL;
+	} else {
+		new_policy = true;
+		policy = cpufreq_policy_alloc(cpu);
+		if (!policy)
+			return -ENOMEM;
+		down_write(&policy->rwsem);
+	}
+
+	if (!new_policy && cpufreq_driver->online) {
+		/* Recover policy->cpus using related_cpus */
+		cpumask_copy(policy->cpus, policy->related_cpus);
+
+		ret = cpufreq_driver->online(policy);
+		if (ret) {
+			pr_debug("%s: %d: initialization failed\n", __func__,
+				 __LINE__);
+			goto out_exit_policy;
+		}
+	} else {
+		cpumask_copy(policy->cpus, cpumask_of(cpu));
+
+		/*
+		 * Call driver. From then on the cpufreq must be able
+		 * to accept all calls to ->verify and ->setpolicy for this CPU.
+		 */
+		ret = cpufreq_driver->init(policy);
+		if (ret) {
+			pr_debug("%s: %d: initialization failed\n", __func__,
+				 __LINE__);
+			goto out_free_policy;
+		}
+
+		/*
+		 * The initialization has succeeded and the policy is online.
+		 * If there is a problem with its frequency table, take it
+		 * offline and drop it.
+		 */
+		ret = cpufreq_table_validate_and_sort(policy);
+		if (ret)
+			goto out_offline_policy;
+
+		/* related_cpus should at least include policy->cpus. */
+		cpumask_copy(policy->related_cpus, policy->cpus);
+	}
+
+	/*
+	 * affected cpus must always be the one, which are online. We aren't
+	 * managing offline cpus here.
+	 */
+	cpumask_and(policy->cpus, policy->cpus, cpu_online_mask);
+
+	if (new_policy) {
+		for_each_cpu(j, policy->related_cpus) {
+			per_cpu(cpufreq_cpu_data, j) = policy;
+			add_cpu_dev_symlink(policy, j, get_cpu_device(j));
+		}
+
+		policy->min_freq_req = kzalloc(2 * sizeof(*policy->min_freq_req),
+					       GFP_KERNEL);
+		if (!policy->min_freq_req) {
+			ret = -ENOMEM;
+			goto out_destroy_policy;
+		}
+
+		ret = freq_qos_add_request(&policy->constraints,
+					   policy->min_freq_req, FREQ_QOS_MIN,
+					   FREQ_QOS_MIN_DEFAULT_VALUE);
+		if (ret < 0) {
+			/*
+			 * So we don't call freq_qos_remove_request() for an
+			 * uninitialized request.
+			 */
+			kfree(policy->min_freq_req);
+			policy->min_freq_req = NULL;
+			goto out_destroy_policy;
+		}
+
+		/*
+		 * This must be initialized right here to avoid calling
+		 * freq_qos_remove_request() on uninitialized request in case
+		 * of errors.
+		 */
+		policy->max_freq_req = policy->min_freq_req + 1;
+
+		ret = freq_qos_add_request(&policy->constraints,
+					   policy->max_freq_req, FREQ_QOS_MAX,
+					   FREQ_QOS_MAX_DEFAULT_VALUE);
+		if (ret < 0) {
+			policy->max_freq_req = NULL;
+			goto out_destroy_policy;
+		}
+
+		blocking_notifier_call_chain(&cpufreq_policy_notifier_list,
+				CPUFREQ_CREATE_POLICY, policy);
+	}
+
+	if (cpufreq_driver->get && has_target()) {
+		policy->cur = cpufreq_driver->get(policy->cpu);
+		if (!policy->cur) {
+			ret = -EIO;
+			pr_err("%s: ->get() failed\n", __func__);
+			goto out_destroy_policy;
+		}
+	}
+
+	/*
+	 * Sometimes boot loaders set CPU frequency to a value outside of
+	 * frequency table present with cpufreq core. In such cases CPU might be
+	 * unstable if it has to run on that frequency for long duration of time
+	 * and so its better to set it to a frequency which is specified in
+	 * freq-table. This also makes cpufreq stats inconsistent as
+	 * cpufreq-stats would fail to register because current frequency of CPU
+	 * isn't found in freq-table.
+	 *
+	 * Because we don't want this change to effect boot process badly, we go
+	 * for the next freq which is >= policy->cur ('cur' must be set by now,
+	 * otherwise we will end up setting freq to lowest of the table as 'cur'
+	 * is initialized to zero).
+	 *
+	 * We are passing target-freq as "policy->cur - 1" otherwise
+	 * __cpufreq_driver_target() would simply fail, as policy->cur will be
+	 * equal to target-freq.
+	 */
+	if ((cpufreq_driver->flags & CPUFREQ_NEED_INITIAL_FREQ_CHECK)
+	    && has_target()) {
+		unsigned int old_freq = policy->cur;
+
+		/* Are we running at unknown frequency ? */
+		ret = cpufreq_frequency_table_get_index(policy, old_freq);
+		if (ret == -EINVAL) {
+			ret = __cpufreq_driver_target(policy, old_freq - 1,
+						      CPUFREQ_RELATION_L);
+
+			/*
+			 * Reaching here after boot in a few seconds may not
+			 * mean that system will remain stable at "unknown"
+			 * frequency for longer duration. Hence, a BUG_ON().
+			 */
+			BUG_ON(ret);
+			pr_info("%s: CPU%d: Running at unlisted initial frequency: %u KHz, changing to: %u KHz\n",
+				__func__, policy->cpu, old_freq, policy->cur);
+		}
+	}
+
+	if (new_policy) {
+		ret = cpufreq_add_dev_interface(policy);
+		if (ret)
+			goto out_destroy_policy;
+
+		cpufreq_stats_create_table(policy);
+
+		write_lock_irqsave(&cpufreq_driver_lock, flags);
+		list_add(&policy->policy_list, &cpufreq_policy_list);
+		write_unlock_irqrestore(&cpufreq_driver_lock, flags);
+
+		/*
+		 * Register with the energy model before
+		 * sched_cpufreq_governor_change() is called, which will result
+		 * in rebuilding of the sched domains, which should only be done
+		 * once the energy model is properly initialized for the policy
+		 * first.
+		 *
+		 * Also, this should be called before the policy is registered
+		 * with cooling framework.
+		 */
+		if (cpufreq_driver->register_em)
+			cpufreq_driver->register_em(policy);
+	}
+
+	ret = cpufreq_init_policy(policy);
+	if (ret) {
+		pr_err("%s: Failed to initialize policy for cpu: %d (%d)\n",
+		       __func__, cpu, ret);
+		goto out_destroy_policy;
+	}
+
+	up_write(&policy->rwsem);
+
+	kobject_uevent(&policy->kobj, KOBJ_ADD);
+
+	/* Callback for handling stuff after policy is ready */
+	if (cpufreq_driver->ready)
+		cpufreq_driver->ready(policy);
+
+	if (cpufreq_thermal_control_enabled(cpufreq_driver))
+		policy->cdev = of_cpufreq_cooling_register(policy);
+
+	pr_debug("initialization complete\n");
+
+	return 0;
+
+out_destroy_policy:
+	for_each_cpu(j, policy->real_cpus)
+		remove_cpu_dev_symlink(policy, j, get_cpu_device(j));
+
+out_offline_policy:
+	if (cpufreq_driver->offline)
+		cpufreq_driver->offline(policy);
+
+out_exit_policy:
+	if (cpufreq_driver->exit)
+		cpufreq_driver->exit(policy);
+
+out_free_policy:
+	cpumask_clear(policy->cpus);
+	up_write(&policy->rwsem);
+
+	cpufreq_policy_free(policy);
+	return ret;
+}
+
+/**
+ * cpufreq_add_dev - the cpufreq interface for a CPU device.
+ * @dev: CPU device.
+ * @sif: Subsystem interface structure pointer (not used)
+ */
+static int cpufreq_add_dev(struct device *dev, struct subsys_interface *sif)
+{
+	struct cpufreq_policy *policy;
+	unsigned cpu = dev->id;
+	int ret;
+
+	dev_dbg(dev, "%s: adding CPU%u\n", __func__, cpu);
+
+	if (cpu_online(cpu)) {
+		ret = cpufreq_online(cpu);
+		if (ret)
+			return ret;
+	}
+
+	/* Create sysfs link on CPU registration */
+	policy = per_cpu(cpufreq_cpu_data, cpu);
+	if (policy)
+		add_cpu_dev_symlink(policy, cpu, dev);
+
+	return 0;
+}
+
+static void __cpufreq_offline(unsigned int cpu, struct cpufreq_policy *policy)
+{
+	int ret;
+
+	if (has_target())
+		cpufreq_stop_governor(policy);
+
+	cpumask_clear_cpu(cpu, policy->cpus);
+
+	if (!policy_is_inactive(policy)) {
+		/* Nominate a new CPU if necessary. */
+		if (cpu == policy->cpu)
+			policy->cpu = cpumask_any(policy->cpus);
+
+		/* Start the governor again for the active policy. */
+		if (has_target()) {
+			ret = cpufreq_start_governor(policy);
+			if (ret)
+				pr_err("%s: Failed to start governor\n", __func__);
+		}
+
+		return;
+	}
+
+	if (has_target())
+		strncpy(policy->last_governor, policy->governor->name,
+			CPUFREQ_NAME_LEN);
+	else
+		policy->last_policy = policy->policy;
+
+	if (cpufreq_thermal_control_enabled(cpufreq_driver)) {
+		cpufreq_cooling_unregister(policy->cdev);
+		policy->cdev = NULL;
+	}
+
+	if (has_target())
+		cpufreq_exit_governor(policy);
+
+	/*
+	 * Perform the ->offline() during light-weight tear-down, as
+	 * that allows fast recovery when the CPU comes back.
+	 */
+	if (cpufreq_driver->offline) {
+		cpufreq_driver->offline(policy);
+	} else if (cpufreq_driver->exit) {
+		cpufreq_driver->exit(policy);
+		policy->freq_table = NULL;
+	}
+}
+
+static int cpufreq_offline(unsigned int cpu)
+{
+	struct cpufreq_policy *policy;
+
+	pr_debug("%s: unregistering CPU %u\n", __func__, cpu);
+
+	policy = cpufreq_cpu_get_raw(cpu);
+	if (!policy) {
+		pr_debug("%s: No cpu_data found\n", __func__);
+		return 0;
+	}
+
+	down_write(&policy->rwsem);
+
+	__cpufreq_offline(cpu, policy);
+
+	up_write(&policy->rwsem);
+	return 0;
+}
+
+/*
+ * cpufreq_remove_dev - remove a CPU device
+ *
+ * Removes the cpufreq interface for a CPU device.
+ */
+static void cpufreq_remove_dev(struct device *dev, struct subsys_interface *sif)
+{
+	unsigned int cpu = dev->id;
+	struct cpufreq_policy *policy = per_cpu(cpufreq_cpu_data, cpu);
+
+	if (!policy)
+		return;
+
+	down_write(&policy->rwsem);
+
+	if (cpu_online(cpu))
+		__cpufreq_offline(cpu, policy);
+
+	remove_cpu_dev_symlink(policy, cpu, dev);
+
+	if (!cpumask_empty(policy->real_cpus)) {
+		up_write(&policy->rwsem);
+		return;
+	}
+
+	/* We did light-weight exit earlier, do full tear down now */
+	if (cpufreq_driver->offline)
+		cpufreq_driver->exit(policy);
+
+	up_write(&policy->rwsem);
+
+	cpufreq_policy_free(policy);
+}
+
+/**
+ * cpufreq_out_of_sync - Fix up actual and saved CPU frequency difference.
+ * @policy: Policy managing CPUs.
+ * @new_freq: New CPU frequency.
+ *
+ * Adjust to the current frequency first and clean up later by either calling
+ * cpufreq_update_policy(), or scheduling handle_update().
+ */
+static void cpufreq_out_of_sync(struct cpufreq_policy *policy,
+				unsigned int new_freq)
+{
+	struct cpufreq_freqs freqs;
+
+	pr_debug("Warning: CPU frequency out of sync: cpufreq and timing core thinks of %u, is %u kHz\n",
+		 policy->cur, new_freq);
+
+	freqs.old = policy->cur;
+	freqs.new = new_freq;
+
+	cpufreq_freq_transition_begin(policy, &freqs);
+	cpufreq_freq_transition_end(policy, &freqs, 0);
+}
+
+static unsigned int cpufreq_verify_current_freq(struct cpufreq_policy *policy, bool update)
+{
+	unsigned int new_freq;
+
+	new_freq = cpufreq_driver->get(policy->cpu);
+	if (!new_freq)
+		return 0;
+
+	/*
+	 * If fast frequency switching is used with the given policy, the check
+	 * against policy->cur is pointless, so skip it in that case.
+	 */
+	if (policy->fast_switch_enabled || !has_target())
+		return new_freq;
+
+	if (policy->cur != new_freq) {
+		/*
+		 * For some platforms, the frequency returned by hardware may be
+		 * slightly different from what is provided in the frequency
+		 * table, for example hardware may return 499 MHz instead of 500
+		 * MHz. In such cases it is better to avoid getting into
+		 * unnecessary frequency updates.
+		 */
+		if (abs(policy->cur - new_freq) < KHZ_PER_MHZ)
+			return policy->cur;
+
+		cpufreq_out_of_sync(policy, new_freq);
+		if (update)
+			schedule_work(&policy->update);
+	}
+
+	return new_freq;
+}
+
+/**
+ * cpufreq_quick_get - get the CPU frequency (in kHz) from policy->cur
+ * @cpu: CPU number
+ *
+ * This is the last known freq, without actually getting it from the driver.
+ * Return value will be same as what is shown in scaling_cur_freq in sysfs.
+ */
+unsigned int cpufreq_quick_get(unsigned int cpu)
+{
+	struct cpufreq_policy *policy;
+	unsigned int ret_freq = 0;
+	unsigned long flags;
+
+	read_lock_irqsave(&cpufreq_driver_lock, flags);
+
+	if (cpufreq_driver && cpufreq_driver->setpolicy && cpufreq_driver->get) {
+		ret_freq = cpufreq_driver->get(cpu);
+		read_unlock_irqrestore(&cpufreq_driver_lock, flags);
+		return ret_freq;
+	}
+
+	read_unlock_irqrestore(&cpufreq_driver_lock, flags);
+
+	policy = cpufreq_cpu_get(cpu);
+	if (policy) {
+		ret_freq = policy->cur;
+		cpufreq_cpu_put(policy);
+	}
+
+	return ret_freq;
+}
+EXPORT_SYMBOL(cpufreq_quick_get);
+
+/**
+ * cpufreq_quick_get_max - get the max reported CPU frequency for this CPU
+ * @cpu: CPU number
+ *
+ * Just return the max possible frequency for a given CPU.
+ */
+unsigned int cpufreq_quick_get_max(unsigned int cpu)
+{
+	struct cpufreq_policy *policy = cpufreq_cpu_get(cpu);
+	unsigned int ret_freq = 0;
+
+	if (policy) {
+		ret_freq = policy->max;
+		cpufreq_cpu_put(policy);
+	}
+
+	return ret_freq;
+}
+EXPORT_SYMBOL(cpufreq_quick_get_max);
+
+/**
+ * cpufreq_get_hw_max_freq - get the max hardware frequency of the CPU
+ * @cpu: CPU number
+ *
+ * The default return value is the max_freq field of cpuinfo.
+ */
+__weak unsigned int cpufreq_get_hw_max_freq(unsigned int cpu)
+{
+	struct cpufreq_policy *policy = cpufreq_cpu_get(cpu);
+	unsigned int ret_freq = 0;
+
+	if (policy) {
+		ret_freq = policy->cpuinfo.max_freq;
+		cpufreq_cpu_put(policy);
+	}
+
+	return ret_freq;
+}
+EXPORT_SYMBOL(cpufreq_get_hw_max_freq);
+
+static unsigned int __cpufreq_get(struct cpufreq_policy *policy)
+{
+	if (unlikely(policy_is_inactive(policy)))
+		return 0;
+
+	return cpufreq_verify_current_freq(policy, true);
+}
+
+/**
+ * cpufreq_get - get the current CPU frequency (in kHz)
+ * @cpu: CPU number
+ *
+ * Get the CPU current (static) CPU frequency
+ */
+unsigned int cpufreq_get(unsigned int cpu)
+{
+	struct cpufreq_policy *policy = cpufreq_cpu_get(cpu);
+	unsigned int ret_freq = 0;
+
+	if (policy) {
+		down_read(&policy->rwsem);
+		if (cpufreq_driver->get)
+			ret_freq = __cpufreq_get(policy);
+		up_read(&policy->rwsem);
+
+		cpufreq_cpu_put(policy);
+	}
+
+	return ret_freq;
+}
+EXPORT_SYMBOL(cpufreq_get);
+
+static struct subsys_interface cpufreq_interface = {
+	.name		= "cpufreq",
+	.subsys		= &cpu_subsys,
+	.add_dev	= cpufreq_add_dev,
+	.remove_dev	= cpufreq_remove_dev,
+};
+
+/*
+ * In case platform wants some specific frequency to be configured
+ * during suspend..
+ */
+int cpufreq_generic_suspend(struct cpufreq_policy *policy)
+{
+	int ret;
+
+	if (!policy->suspend_freq) {
+		pr_debug("%s: suspend_freq not defined\n", __func__);
+		return 0;
+	}
+
+	pr_debug("%s: Setting suspend-freq: %u\n", __func__,
+			policy->suspend_freq);
+
+	ret = __cpufreq_driver_target(policy, policy->suspend_freq,
+			CPUFREQ_RELATION_H);
+	if (ret)
+		pr_err("%s: unable to set suspend-freq: %u. err: %d\n",
+				__func__, policy->suspend_freq, ret);
+
+	return ret;
+}
+EXPORT_SYMBOL(cpufreq_generic_suspend);
+
+/**
+ * cpufreq_suspend() - Suspend CPUFreq governors.
+ *
+ * Called during system wide Suspend/Hibernate cycles for suspending governors
+ * as some platforms can't change frequency after this point in suspend cycle.
+ * Because some of the devices (like: i2c, regulators, etc) they use for
+ * changing frequency are suspended quickly after this point.
+ */
+void cpufreq_suspend(void)
+{
+	struct cpufreq_policy *policy;
+
+	if (!cpufreq_driver)
+		return;
+
+	if (!has_target() && !cpufreq_driver->suspend)
+		goto suspend;
+
+	pr_debug("%s: Suspending Governors\n", __func__);
+
+	for_each_active_policy(policy) {
+		if (has_target()) {
+			down_write(&policy->rwsem);
+			cpufreq_stop_governor(policy);
+			up_write(&policy->rwsem);
+		}
+
+		if (cpufreq_driver->suspend && cpufreq_driver->suspend(policy))
+			pr_err("%s: Failed to suspend driver: %s\n", __func__,
+				cpufreq_driver->name);
+	}
+
+suspend:
+	cpufreq_suspended = true;
+}
+
+/**
+ * cpufreq_resume() - Resume CPUFreq governors.
+ *
+ * Called during system wide Suspend/Hibernate cycle for resuming governors that
+ * are suspended with cpufreq_suspend().
+ */
+void cpufreq_resume(void)
+{
+	struct cpufreq_policy *policy;
+	int ret;
+
+	if (!cpufreq_driver)
+		return;
+
+	if (unlikely(!cpufreq_suspended))
+		return;
+
+	cpufreq_suspended = false;
+
+	if (!has_target() && !cpufreq_driver->resume)
+		return;
+
+	pr_debug("%s: Resuming Governors\n", __func__);
+
+	for_each_active_policy(policy) {
+		if (cpufreq_driver->resume && cpufreq_driver->resume(policy)) {
+			pr_err("%s: Failed to resume driver: %p\n", __func__,
+				policy);
+		} else if (has_target()) {
+			down_write(&policy->rwsem);
+			ret = cpufreq_start_governor(policy);
+			up_write(&policy->rwsem);
+
+			if (ret)
+				pr_err("%s: Failed to start governor for policy: %p\n",
+				       __func__, policy);
+		}
+	}
+}
+
+/**
+ * cpufreq_driver_test_flags - Test cpufreq driver's flags against given ones.
+ * @flags: Flags to test against the current cpufreq driver's flags.
+ *
+ * Assumes that the driver is there, so callers must ensure that this is the
+ * case.
+ */
+bool cpufreq_driver_test_flags(u16 flags)
+{
+	return !!(cpufreq_driver->flags & flags);
+}
+
+/**
+ * cpufreq_get_current_driver - Return the current driver's name.
+ *
+ * Return the name string of the currently registered cpufreq driver or NULL if
+ * none.
+ */
+const char *cpufreq_get_current_driver(void)
+{
+	if (cpufreq_driver)
+		return cpufreq_driver->name;
+
+	return NULL;
+}
+EXPORT_SYMBOL_GPL(cpufreq_get_current_driver);
+
+/**
+ * cpufreq_get_driver_data - Return current driver data.
+ *
+ * Return the private data of the currently registered cpufreq driver, or NULL
+ * if no cpufreq driver has been registered.
+ */
+void *cpufreq_get_driver_data(void)
+{
+	if (cpufreq_driver)
+		return cpufreq_driver->driver_data;
+
+	return NULL;
+}
+EXPORT_SYMBOL_GPL(cpufreq_get_driver_data);
+
+/*********************************************************************
+ *                     NOTIFIER LISTS INTERFACE                      *
+ *********************************************************************/
+
+/**
+ * cpufreq_register_notifier - Register a notifier with cpufreq.
+ * @nb: notifier function to register.
+ * @list: CPUFREQ_TRANSITION_NOTIFIER or CPUFREQ_POLICY_NOTIFIER.
+ *
+ * Add a notifier to one of two lists: either a list of notifiers that run on
+ * clock rate changes (once before and once after every transition), or a list
+ * of notifiers that ron on cpufreq policy changes.
+ *
+ * This function may sleep and it has the same return values as
+ * blocking_notifier_chain_register().
+ */
+int cpufreq_register_notifier(struct notifier_block *nb, unsigned int list)
+{
+	int ret;
+
+	if (cpufreq_disabled())
+		return -EINVAL;
+
+	switch (list) {
+	case CPUFREQ_TRANSITION_NOTIFIER:
+		mutex_lock(&cpufreq_fast_switch_lock);
+
+		if (cpufreq_fast_switch_count > 0) {
+			mutex_unlock(&cpufreq_fast_switch_lock);
+			return -EBUSY;
+		}
+		ret = srcu_notifier_chain_register(
+				&cpufreq_transition_notifier_list, nb);
+		if (!ret)
+			cpufreq_fast_switch_count--;
+
+		mutex_unlock(&cpufreq_fast_switch_lock);
+		break;
+	case CPUFREQ_POLICY_NOTIFIER:
+		ret = blocking_notifier_chain_register(
+				&cpufreq_policy_notifier_list, nb);
+		break;
+	default:
+		ret = -EINVAL;
+	}
+
+	return ret;
+}
+EXPORT_SYMBOL(cpufreq_register_notifier);
+
+/**
+ * cpufreq_unregister_notifier - Unregister a notifier from cpufreq.
+ * @nb: notifier block to be unregistered.
+ * @list: CPUFREQ_TRANSITION_NOTIFIER or CPUFREQ_POLICY_NOTIFIER.
+ *
+ * Remove a notifier from one of the cpufreq notifier lists.
+ *
+ * This function may sleep and it has the same return values as
+ * blocking_notifier_chain_unregister().
+ */
+int cpufreq_unregister_notifier(struct notifier_block *nb, unsigned int list)
+{
+	int ret;
+
+	if (cpufreq_disabled())
+		return -EINVAL;
+
+	switch (list) {
+	case CPUFREQ_TRANSITION_NOTIFIER:
+		mutex_lock(&cpufreq_fast_switch_lock);
+
+		ret = srcu_notifier_chain_unregister(
+				&cpufreq_transition_notifier_list, nb);
+		if (!ret && !WARN_ON(cpufreq_fast_switch_count >= 0))
+			cpufreq_fast_switch_count++;
+
+		mutex_unlock(&cpufreq_fast_switch_lock);
+		break;
+	case CPUFREQ_POLICY_NOTIFIER:
+		ret = blocking_notifier_chain_unregister(
+				&cpufreq_policy_notifier_list, nb);
+		break;
+	default:
+		ret = -EINVAL;
+	}
+
+	return ret;
+}
+EXPORT_SYMBOL(cpufreq_unregister_notifier);
+
+
+/*********************************************************************
+ *                              GOVERNORS                            *
+ *********************************************************************/
+
+/**
+ * cpufreq_driver_fast_switch - Carry out a fast CPU frequency switch.
+ * @policy: cpufreq policy to switch the frequency for.
+ * @target_freq: New frequency to set (may be approximate).
+ *
+ * Carry out a fast frequency switch without sleeping.
+ *
+ * The driver's ->fast_switch() callback invoked by this function must be
+ * suitable for being called from within RCU-sched read-side critical sections
+ * and it is expected to select the minimum available frequency greater than or
+ * equal to @target_freq (CPUFREQ_RELATION_L).
+ *
+ * This function must not be called if policy->fast_switch_enabled is unset.
+ *
+ * Governors calling this function must guarantee that it will never be invoked
+ * twice in parallel for the same policy and that it will never be called in
+ * parallel with either ->target() or ->target_index() for the same policy.
+ *
+ * Returns the actual frequency set for the CPU.
+ *
+ * If 0 is returned by the driver's ->fast_switch() callback to indicate an
+ * error condition, the hardware configuration must be preserved.
+ */
+unsigned int cpufreq_driver_fast_switch(struct cpufreq_policy *policy,
+					unsigned int target_freq)
+{
+	unsigned int freq;
+	int cpu;
+
+	target_freq = clamp_val(target_freq, policy->min, policy->max);
+	freq = cpufreq_driver->fast_switch(policy, target_freq);
+
+	if (!freq)
+		return 0;
+
+	policy->cur = freq;
+	arch_set_freq_scale(policy->related_cpus, freq,
+			    policy->cpuinfo.max_freq);
+	cpufreq_stats_record_transition(policy, freq);
+
+	if (trace_cpu_frequency_enabled()) {
+		for_each_cpu(cpu, policy->cpus)
+			trace_cpu_frequency(freq, cpu);
+	}
+
+	return freq;
+}
+EXPORT_SYMBOL_GPL(cpufreq_driver_fast_switch);
+
+/**
+ * cpufreq_driver_adjust_perf - Adjust CPU performance level in one go.
+ * @cpu: Target CPU.
+ * @min_perf: Minimum (required) performance level (units of @capacity).
+ * @target_perf: Target (desired) performance level (units of @capacity).
+ * @capacity: Capacity of the target CPU.
+ *
+ * Carry out a fast performance level switch of @cpu without sleeping.
+ *
+ * The driver's ->adjust_perf() callback invoked by this function must be
+ * suitable for being called from within RCU-sched read-side critical sections
+ * and it is expected to select a suitable performance level equal to or above
+ * @min_perf and preferably equal to or below @target_perf.
+ *
+ * This function must not be called if policy->fast_switch_enabled is unset.
+ *
+ * Governors calling this function must guarantee that it will never be invoked
+ * twice in parallel for the same CPU and that it will never be called in
+ * parallel with either ->target() or ->target_index() or ->fast_switch() for
+ * the same CPU.
+ */
+void cpufreq_driver_adjust_perf(unsigned int cpu,
+				 unsigned long min_perf,
+				 unsigned long target_perf,
+				 unsigned long capacity)
+{
+	cpufreq_driver->adjust_perf(cpu, min_perf, target_perf, capacity);
+}
+
+/**
+ * cpufreq_driver_has_adjust_perf - Check "direct fast switch" callback.
+ *
+ * Return 'true' if the ->adjust_perf callback is present for the
+ * current driver or 'false' otherwise.
+ */
+bool cpufreq_driver_has_adjust_perf(void)
+{
+	return !!cpufreq_driver->adjust_perf;
+}
+
+/* Must set freqs->new to intermediate frequency */
+static int __target_intermediate(struct cpufreq_policy *policy,
+				 struct cpufreq_freqs *freqs, int index)
+{
+	int ret;
+
+	freqs->new = cpufreq_driver->get_intermediate(policy, index);
+
+	/* We don't need to switch to intermediate freq */
+	if (!freqs->new)
+		return 0;
+
+	pr_debug("%s: cpu: %d, switching to intermediate freq: oldfreq: %u, intermediate freq: %u\n",
+		 __func__, policy->cpu, freqs->old, freqs->new);
+
+	cpufreq_freq_transition_begin(policy, freqs);
+	ret = cpufreq_driver->target_intermediate(policy, index);
+	cpufreq_freq_transition_end(policy, freqs, ret);
+
+	if (ret)
+		pr_err("%s: Failed to change to intermediate frequency: %d\n",
+		       __func__, ret);
+
+	return ret;
+}
+
+static int __target_index(struct cpufreq_policy *policy, int index)
+{
+	struct cpufreq_freqs freqs = {.old = policy->cur, .flags = 0};
+	unsigned int restore_freq, intermediate_freq = 0;
+	unsigned int newfreq = policy->freq_table[index].frequency;
+	int retval = -EINVAL;
+	bool notify;
+
+	if (newfreq == policy->cur)
+		return 0;
+
+	/* Save last value to restore later on errors */
+	restore_freq = policy->cur;
+
+	notify = !(cpufreq_driver->flags & CPUFREQ_ASYNC_NOTIFICATION);
+	if (notify) {
+		/* Handle switching to intermediate frequency */
+		if (cpufreq_driver->get_intermediate) {
+			retval = __target_intermediate(policy, &freqs, index);
+			if (retval)
+				return retval;
+
+			intermediate_freq = freqs.new;
+			/* Set old freq to intermediate */
+			if (intermediate_freq)
+				freqs.old = freqs.new;
+		}
+
+		freqs.new = newfreq;
+		pr_debug("%s: cpu: %d, oldfreq: %u, new freq: %u\n",
+			 __func__, policy->cpu, freqs.old, freqs.new);
+
+		cpufreq_freq_transition_begin(policy, &freqs);
+	}
+
+	retval = cpufreq_driver->target_index(policy, index);
+	if (retval)
+		pr_err("%s: Failed to change cpu frequency: %d\n", __func__,
+		       retval);
+
+	if (notify) {
+		cpufreq_freq_transition_end(policy, &freqs, retval);
+
+		/*
+		 * Failed after setting to intermediate freq? Driver should have
+		 * reverted back to initial frequency and so should we. Check
+		 * here for intermediate_freq instead of get_intermediate, in
+		 * case we haven't switched to intermediate freq at all.
+		 */
+		if (unlikely(retval && intermediate_freq)) {
+			freqs.old = intermediate_freq;
+			freqs.new = restore_freq;
+			cpufreq_freq_transition_begin(policy, &freqs);
+			cpufreq_freq_transition_end(policy, &freqs, 0);
+		}
+	}
+
+	return retval;
+}
+
+int __cpufreq_driver_target(struct cpufreq_policy *policy,
+			    unsigned int target_freq,
+			    unsigned int relation)
+{
+	unsigned int old_target_freq = target_freq;
+
+	if (cpufreq_disabled())
+		return -ENODEV;
+
+	target_freq = __resolve_freq(policy, target_freq, relation);
+
+	pr_debug("target for CPU %u: %u kHz, relation %u, requested %u kHz\n",
+		 policy->cpu, target_freq, relation, old_target_freq);
+
+	/*
+	 * This might look like a redundant call as we are checking it again
+	 * after finding index. But it is left intentionally for cases where
+	 * exactly same freq is called again and so we can save on few function
+	 * calls.
+	 */
+	if (target_freq == policy->cur &&
+	    !(cpufreq_driver->flags & CPUFREQ_NEED_UPDATE_LIMITS))
+		return 0;
+
+	if (cpufreq_driver->target) {
+		/*
+		 * If the driver hasn't setup a single inefficient frequency,
+		 * it's unlikely it knows how to decode CPUFREQ_RELATION_E.
+		 */
+		if (!policy->efficiencies_available)
+			relation &= ~CPUFREQ_RELATION_E;
+
+		return cpufreq_driver->target(policy, target_freq, relation);
+	}
+
+	if (!cpufreq_driver->target_index)
+		return -EINVAL;
+
+	return __target_index(policy, policy->cached_resolved_idx);
+}
+EXPORT_SYMBOL_GPL(__cpufreq_driver_target);
+
+int cpufreq_driver_target(struct cpufreq_policy *policy,
+			  unsigned int target_freq,
+			  unsigned int relation)
+{
+	int ret;
+
+	down_write(&policy->rwsem);
+
+	ret = __cpufreq_driver_target(policy, target_freq, relation);
+
+	up_write(&policy->rwsem);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(cpufreq_driver_target);
+
+__weak struct cpufreq_governor *cpufreq_fallback_governor(void)
+{
+	return NULL;
+}
+
+static int cpufreq_init_governor(struct cpufreq_policy *policy)
+{
+	int ret;
+
+	/* Don't start any governor operations if we are entering suspend */
+	if (cpufreq_suspended)
+		return 0;
+	/*
+	 * Governor might not be initiated here if ACPI _PPC changed
+	 * notification happened, so check it.
+	 */
+	if (!policy->governor)
+		return -EINVAL;
+
+	/* Platform doesn't want dynamic frequency switching ? */
+	if (policy->governor->flags & CPUFREQ_GOV_DYNAMIC_SWITCHING &&
+	    cpufreq_driver->flags & CPUFREQ_NO_AUTO_DYNAMIC_SWITCHING) {
+		struct cpufreq_governor *gov = cpufreq_fallback_governor();
+
+		if (gov) {
+			pr_warn("Can't use %s governor as dynamic switching is disallowed. Fallback to %s governor\n",
+				policy->governor->name, gov->name);
+			policy->governor = gov;
+		} else {
+			return -EINVAL;
+		}
+	}
+
+	if (!try_module_get(policy->governor->owner))
+		return -EINVAL;
+
+	pr_debug("%s: for CPU %u\n", __func__, policy->cpu);
+
+	if (policy->governor->init) {
+		ret = policy->governor->init(policy);
+		if (ret) {
+			module_put(policy->governor->owner);
+			return ret;
+		}
+	}
+
+	policy->strict_target = !!(policy->governor->flags & CPUFREQ_GOV_STRICT_TARGET);
+
+	return 0;
+}
+
+static void cpufreq_exit_governor(struct cpufreq_policy *policy)
+{
+	if (cpufreq_suspended || !policy->governor)
+		return;
+
+	pr_debug("%s: for CPU %u\n", __func__, policy->cpu);
+
+	if (policy->governor->exit)
+		policy->governor->exit(policy);
+
+	module_put(policy->governor->owner);
+}
+
+int cpufreq_start_governor(struct cpufreq_policy *policy)
+{
+	int ret;
+
+	if (cpufreq_suspended)
+		return 0;
+
+	if (!policy->governor)
+		return -EINVAL;
+
+	pr_debug("%s: for CPU %u\n", __func__, policy->cpu);
+
+	if (cpufreq_driver->get)
+		cpufreq_verify_current_freq(policy, false);
+
+	if (policy->governor->start) {
+		ret = policy->governor->start(policy);
+		if (ret)
+			return ret;
+	}
+
+	if (policy->governor->limits)
+		policy->governor->limits(policy);
+
+	return 0;
+}
+
+void cpufreq_stop_governor(struct cpufreq_policy *policy)
+{
+	if (cpufreq_suspended || !policy->governor)
+		return;
+
+	pr_debug("%s: for CPU %u\n", __func__, policy->cpu);
+
+	if (policy->governor->stop)
+		policy->governor->stop(policy);
+}
+
+static void cpufreq_governor_limits(struct cpufreq_policy *policy)
+{
+	if (cpufreq_suspended || !policy->governor)
+		return;
+
+	pr_debug("%s: for CPU %u\n", __func__, policy->cpu);
+
+	if (policy->governor->limits)
+		policy->governor->limits(policy);
+}
+
+int cpufreq_register_governor(struct cpufreq_governor *governor)
+{
+	int err;
+
+	if (!governor)
+		return -EINVAL;
+
+	if (cpufreq_disabled())
+		return -ENODEV;
+
+	mutex_lock(&cpufreq_governor_mutex);
+
+	err = -EBUSY;
+	if (!find_governor(governor->name)) {
+		err = 0;
+		list_add(&governor->governor_list, &cpufreq_governor_list);
+	}
+
+	mutex_unlock(&cpufreq_governor_mutex);
+	return err;
+}
+EXPORT_SYMBOL_GPL(cpufreq_register_governor);
+
+void cpufreq_unregister_governor(struct cpufreq_governor *governor)
+{
+	struct cpufreq_policy *policy;
+	unsigned long flags;
+
+	if (!governor)
+		return;
+
+	if (cpufreq_disabled())
+		return;
+
+	/* clear last_governor for all inactive policies */
+	read_lock_irqsave(&cpufreq_driver_lock, flags);
+	for_each_inactive_policy(policy) {
+		if (!strcmp(policy->last_governor, governor->name)) {
+			policy->governor = NULL;
+			strcpy(policy->last_governor, "\0");
+		}
+	}
+	read_unlock_irqrestore(&cpufreq_driver_lock, flags);
+
+	mutex_lock(&cpufreq_governor_mutex);
+	list_del(&governor->governor_list);
+	mutex_unlock(&cpufreq_governor_mutex);
+}
+EXPORT_SYMBOL_GPL(cpufreq_unregister_governor);
+
+
+/*********************************************************************
+ *                          POLICY INTERFACE                         *
+ *********************************************************************/
+
+/**
+ * cpufreq_get_policy - get the current cpufreq_policy
+ * @policy: struct cpufreq_policy into which the current cpufreq_policy
+ *	is written
+ * @cpu: CPU to find the policy for
+ *
+ * Reads the current cpufreq policy.
+ */
+int cpufreq_get_policy(struct cpufreq_policy *policy, unsigned int cpu)
+{
+	struct cpufreq_policy *cpu_policy;
+	if (!policy)
+		return -EINVAL;
+
+	cpu_policy = cpufreq_cpu_get(cpu);
+	if (!cpu_policy)
+		return -EINVAL;
+
+	memcpy(policy, cpu_policy, sizeof(*policy));
+
+	cpufreq_cpu_put(cpu_policy);
+	return 0;
+}
+EXPORT_SYMBOL(cpufreq_get_policy);
+
+/**
+ * cpufreq_set_policy - Modify cpufreq policy parameters.
+ * @policy: Policy object to modify.
+ * @new_gov: Policy governor pointer.
+ * @new_pol: Policy value (for drivers with built-in governors).
+ *
+ * Invoke the cpufreq driver's ->verify() callback to sanity-check the frequency
+ * limits to be set for the policy, update @policy with the verified limits
+ * values and either invoke the driver's ->setpolicy() callback (if present) or
+ * carry out a governor update for @policy.  That is, run the current governor's
+ * ->limits() callback (if @new_gov points to the same object as the one in
+ * @policy) or replace the governor for @policy with @new_gov.
+ *
+ * The cpuinfo part of @policy is not updated by this function.
+ */
+static int cpufreq_set_policy(struct cpufreq_policy *policy,
+			      struct cpufreq_governor *new_gov,
+			      unsigned int new_pol)
+{
+	struct cpufreq_policy_data new_data;
+	struct cpufreq_governor *old_gov;
+	int ret;
+
+	memcpy(&new_data.cpuinfo, &policy->cpuinfo, sizeof(policy->cpuinfo));
+	new_data.freq_table = policy->freq_table;
+	new_data.cpu = policy->cpu;
+	/*
+	 * PM QoS framework collects all the requests from users and provide us
+	 * the final aggregated value here.
+	 */
+	new_data.min = freq_qos_read_value(&policy->constraints, FREQ_QOS_MIN);
+	new_data.max = freq_qos_read_value(&policy->constraints, FREQ_QOS_MAX);
+
+	pr_debug("setting new policy for CPU %u: %u - %u kHz\n",
+		 new_data.cpu, new_data.min, new_data.max);
+
+	/*
+	 * Verify that the CPU speed can be set within these limits and make sure
+	 * that min <= max.
+	 */
+	ret = cpufreq_driver->verify(&new_data);
+	if (ret)
+		return ret;
+
+	/*
+	 * Resolve policy min/max to available frequencies. It ensures
+	 * no frequency resolution will neither overshoot the requested maximum
+	 * nor undershoot the requested minimum.
+	 */
+	policy->min = new_data.min;
+	policy->max = new_data.max;
+	policy->min = __resolve_freq(policy, policy->min, CPUFREQ_RELATION_L);
+	policy->max = __resolve_freq(policy, policy->max, CPUFREQ_RELATION_H);
+	trace_cpu_frequency_limits(policy);
+
+	policy->cached_target_freq = UINT_MAX;
+
+	pr_debug("new min and max freqs are %u - %u kHz\n",
+		 policy->min, policy->max);
+
+	if (cpufreq_driver->setpolicy) {
+		policy->policy = new_pol;
+		pr_debug("setting range\n");
+		return cpufreq_driver->setpolicy(policy);
+	}
+
+	if (new_gov == policy->governor) {
+		pr_debug("governor limits update\n");
+		cpufreq_governor_limits(policy);
+		return 0;
+	}
+
+	pr_debug("governor switch\n");
+
+	/* save old, working values */
+	old_gov = policy->governor;
+	/* end old governor */
+	if (old_gov) {
+		cpufreq_stop_governor(policy);
+		cpufreq_exit_governor(policy);
+	}
+
+	/* start new governor */
+	policy->governor = new_gov;
+	ret = cpufreq_init_governor(policy);
+	if (!ret) {
+		ret = cpufreq_start_governor(policy);
+		if (!ret) {
+			pr_debug("governor change\n");
+			sched_cpufreq_governor_change(policy, old_gov);
+			return 0;
+		}
+		cpufreq_exit_governor(policy);
+	}
+
+	/* new governor failed, so re-start old one */
+	pr_debug("starting governor %s failed\n", policy->governor->name);
+	if (old_gov) {
+		policy->governor = old_gov;
+		if (cpufreq_init_governor(policy))
+			policy->governor = NULL;
+		else
+			cpufreq_start_governor(policy);
+	}
+
+	return ret;
+}
+
+/**
+ * cpufreq_update_policy - Re-evaluate an existing cpufreq policy.
+ * @cpu: CPU to re-evaluate the policy for.
+ *
+ * Update the current frequency for the cpufreq policy of @cpu and use
+ * cpufreq_set_policy() to re-apply the min and max limits, which triggers the
+ * evaluation of policy notifiers and the cpufreq driver's ->verify() callback
+ * for the policy in question, among other things.
+ */
+void cpufreq_update_policy(unsigned int cpu)
+{
+	struct cpufreq_policy *policy = cpufreq_cpu_acquire(cpu);
+
+	if (!policy)
+		return;
+
+	/*
+	 * BIOS might change freq behind our back
+	 * -> ask driver for current freq and notify governors about a change
+	 */
+	if (cpufreq_driver->get && has_target() &&
+	    (cpufreq_suspended || WARN_ON(!cpufreq_verify_current_freq(policy, false))))
+		goto unlock;
+
+	refresh_frequency_limits(policy);
+
+unlock:
+	cpufreq_cpu_release(policy);
+}
+EXPORT_SYMBOL(cpufreq_update_policy);
+
+/**
+ * cpufreq_update_limits - Update policy limits for a given CPU.
+ * @cpu: CPU to update the policy limits for.
+ *
+ * Invoke the driver's ->update_limits callback if present or call
+ * cpufreq_update_policy() for @cpu.
+ */
+void cpufreq_update_limits(unsigned int cpu)
+{
+	if (cpufreq_driver->update_limits)
+		cpufreq_driver->update_limits(cpu);
+	else
+		cpufreq_update_policy(cpu);
+}
+EXPORT_SYMBOL_GPL(cpufreq_update_limits);
+
+/*********************************************************************
+ *               BOOST						     *
+ *********************************************************************/
+static int cpufreq_boost_set_sw(struct cpufreq_policy *policy, int state)
+{
+	int ret;
+
+	if (!policy->freq_table)
+		return -ENXIO;
+
+	ret = cpufreq_frequency_table_cpuinfo(policy, policy->freq_table);
+	if (ret) {
+		pr_err("%s: Policy frequency update failed\n", __func__);
+		return ret;
+	}
+
+	ret = freq_qos_update_request(policy->max_freq_req, policy->max);
+	if (ret < 0)
+		return ret;
+
+	return 0;
+}
+
+int cpufreq_boost_trigger_state(int state)
+{
+	struct cpufreq_policy *policy;
+	unsigned long flags;
+	int ret = 0;
+
+	if (cpufreq_driver->boost_enabled == state)
+		return 0;
+
+	write_lock_irqsave(&cpufreq_driver_lock, flags);
+	cpufreq_driver->boost_enabled = state;
+	write_unlock_irqrestore(&cpufreq_driver_lock, flags);
+
+	cpus_read_lock();
+	for_each_active_policy(policy) {
+		ret = cpufreq_driver->set_boost(policy, state);
+		if (ret)
+			goto err_reset_state;
+	}
+	cpus_read_unlock();
+
+	return 0;
+
+err_reset_state:
+	cpus_read_unlock();
+
+	write_lock_irqsave(&cpufreq_driver_lock, flags);
+	cpufreq_driver->boost_enabled = !state;
+	write_unlock_irqrestore(&cpufreq_driver_lock, flags);
+
+	pr_err("%s: Cannot %s BOOST\n",
+	       __func__, state ? "enable" : "disable");
+
+	return ret;
+}
+
+static bool cpufreq_boost_supported(void)
+{
+	return cpufreq_driver->set_boost;
+}
+
+static int create_boost_sysfs_file(void)
+{
+	int ret;
+
+	ret = sysfs_create_file(cpufreq_global_kobject, &boost.attr);
+	if (ret)
+		pr_err("%s: cannot register global BOOST sysfs file\n",
+		       __func__);
+
+	return ret;
+}
+
+static void remove_boost_sysfs_file(void)
+{
+	if (cpufreq_boost_supported())
+		sysfs_remove_file(cpufreq_global_kobject, &boost.attr);
+}
+
+int cpufreq_enable_boost_support(void)
+{
+	if (!cpufreq_driver)
+		return -EINVAL;
+
+	if (cpufreq_boost_supported())
+		return 0;
+
+	cpufreq_driver->set_boost = cpufreq_boost_set_sw;
+
+	/* This will get removed on driver unregister */
+	return create_boost_sysfs_file();
+}
+EXPORT_SYMBOL_GPL(cpufreq_enable_boost_support);
+
+int cpufreq_boost_enabled(void)
+{
+	return cpufreq_driver->boost_enabled;
+}
+EXPORT_SYMBOL_GPL(cpufreq_boost_enabled);
+
+/*********************************************************************
+ *               REGISTER / UNREGISTER CPUFREQ DRIVER                *
+ *********************************************************************/
+static enum cpuhp_state hp_online;
+
+static int cpuhp_cpufreq_online(unsigned int cpu)
+{
+	cpufreq_online(cpu);
+
+	return 0;
+}
+
+static int cpuhp_cpufreq_offline(unsigned int cpu)
+{
+	cpufreq_offline(cpu);
+
+	return 0;
+}
+
+/**
+ * cpufreq_register_driver - register a CPU Frequency driver
+ * @driver_data: A struct cpufreq_driver containing the values#
+ * submitted by the CPU Frequency driver.
+ *
+ * Registers a CPU Frequency driver to this core code. This code
+ * returns zero on success, -EEXIST when another driver got here first
+ * (and isn't unregistered in the meantime).
+ *
+ */
+int cpufreq_register_driver(struct cpufreq_driver *driver_data)
+{
+	unsigned long flags;
+	int ret;
+
+	if (cpufreq_disabled())
+		return -ENODEV;
+
+	/*
+	 * The cpufreq core depends heavily on the availability of device
+	 * structure, make sure they are available before proceeding further.
+	 */
+	if (!get_cpu_device(0))
+		return -EPROBE_DEFER;
+
+	if (!driver_data || !driver_data->verify || !driver_data->init ||
+	    !(driver_data->setpolicy || driver_data->target_index ||
+		    driver_data->target) ||
+	     (driver_data->setpolicy && (driver_data->target_index ||
+		    driver_data->target)) ||
+	     (!driver_data->get_intermediate != !driver_data->target_intermediate) ||
+	     (!driver_data->online != !driver_data->offline))
+		return -EINVAL;
+
+	pr_debug("trying to register driver %s\n", driver_data->name);
+
+	/* Protect against concurrent CPU online/offline. */
+	cpus_read_lock();
+
+	write_lock_irqsave(&cpufreq_driver_lock, flags);
+	if (cpufreq_driver) {
+		write_unlock_irqrestore(&cpufreq_driver_lock, flags);
+		ret = -EEXIST;
+		goto out;
+	}
+	cpufreq_driver = driver_data;
+	write_unlock_irqrestore(&cpufreq_driver_lock, flags);
+
+	/*
+	 * Mark support for the scheduler's frequency invariance engine for
+	 * drivers that implement target(), target_index() or fast_switch().
+	 */
+	if (!cpufreq_driver->setpolicy) {
+		static_branch_enable_cpuslocked(&cpufreq_freq_invariance);
+		pr_debug("supports frequency invariance");
+	}
+
+	if (driver_data->setpolicy)
+		driver_data->flags |= CPUFREQ_CONST_LOOPS;
+
+	if (cpufreq_boost_supported()) {
+		ret = create_boost_sysfs_file();
+		if (ret)
+			goto err_null_driver;
+	}
+
+	ret = subsys_interface_register(&cpufreq_interface);
+	if (ret)
+		goto err_boost_unreg;
+
+	if (unlikely(list_empty(&cpufreq_policy_list))) {
+		/* if all ->init() calls failed, unregister */
+		ret = -ENODEV;
+		pr_debug("%s: No CPU initialized for driver %s\n", __func__,
+			 driver_data->name);
+		goto err_if_unreg;
+	}
+
+	ret = cpuhp_setup_state_nocalls_cpuslocked(CPUHP_AP_ONLINE_DYN,
+						   "cpufreq:online",
+						   cpuhp_cpufreq_online,
+						   cpuhp_cpufreq_offline);
+	if (ret < 0)
+		goto err_if_unreg;
+	hp_online = ret;
+	ret = 0;
+
+	pr_debug("driver %s up and running\n", driver_data->name);
+	goto out;
+
+err_if_unreg:
+	subsys_interface_unregister(&cpufreq_interface);
+err_boost_unreg:
+	remove_boost_sysfs_file();
+err_null_driver:
+	write_lock_irqsave(&cpufreq_driver_lock, flags);
+	cpufreq_driver = NULL;
+	write_unlock_irqrestore(&cpufreq_driver_lock, flags);
+out:
+	cpus_read_unlock();
+	return ret;
+}
+EXPORT_SYMBOL_GPL(cpufreq_register_driver);
+
+/*
+ * cpufreq_unregister_driver - unregister the current CPUFreq driver
+ *
+ * Unregister the current CPUFreq driver. Only call this if you have
+ * the right to do so, i.e. if you have succeeded in initialising before!
+ * Returns zero if successful, and -EINVAL if the cpufreq_driver is
+ * currently not initialised.
+ */
+int cpufreq_unregister_driver(struct cpufreq_driver *driver)
+{
+	unsigned long flags;
+
+	if (!cpufreq_driver || (driver != cpufreq_driver))
+		return -EINVAL;
+
+	pr_debug("unregistering driver %s\n", driver->name);
+
+	/* Protect against concurrent cpu hotplug */
+	cpus_read_lock();
+	subsys_interface_unregister(&cpufreq_interface);
+	remove_boost_sysfs_file();
+	static_branch_disable_cpuslocked(&cpufreq_freq_invariance);
+	cpuhp_remove_state_nocalls_cpuslocked(hp_online);
+
+	write_lock_irqsave(&cpufreq_driver_lock, flags);
+
+	cpufreq_driver = NULL;
+
+	write_unlock_irqrestore(&cpufreq_driver_lock, flags);
+	cpus_read_unlock();
+
+	return 0;
+}
+EXPORT_SYMBOL_GPL(cpufreq_unregister_driver);
+
+static int __init cpufreq_core_init(void)
+{
+	struct cpufreq_governor *gov = cpufreq_default_governor();
+
+	if (cpufreq_disabled())
+		return -ENODEV;
+
+	cpufreq_global_kobject = kobject_create_and_add("cpufreq", &cpu_subsys.dev_root->kobj);
+	BUG_ON(!cpufreq_global_kobject);
+
+	if (!strlen(default_governor))
+		strncpy(default_governor, gov->name, CPUFREQ_NAME_LEN);
+
+	return 0;
+}
+module_param(off, int, 0444);
+module_param_string(default_governor, default_governor, CPUFREQ_NAME_LEN, 0444);
+core_initcall(cpufreq_core_init);