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	Version: linux-6.0.1 spark-3.0.0 hadoop-3.2.0-src hadoop-3.3.0-src spark-2.4.7 linux-4.15.13 hadoop-2.7.4-src Revert   Change

 // 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);
 
     policy->transition_ongoing = false;
     policy->transition_task = NULL;
 
     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;
 
     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_completion(&policy->kobj_unregister);
     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) < HZ_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);