text: /*
   *  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
   *
   * This program is free software; you can redistribute it and/or modify
   * it under the terms of the GNU General Public License version 2 as
   * published by the Free Software Foundation.
   */
  
  #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
  
  #include <linux/cpu.h>
  #include <linux/cpufreq.h>
  #include <linux/cpufreq_times.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/slab.h>
  #include <linux/suspend.h>
  #include <linux/syscore_ops.h>
  #include <linux/tick.h>
  #ifdef CONFIG_SMP
  #include <linux/sched.h>
  #endif
  #include <trace/events/power.h>
  
  static LIST_HEAD(cpufreq_policy_list);
  
  static inline bool policy_is_inactive(struct cpufreq_policy *policy)
  {
  	return cpumask_empty(policy->cpus);
  }
  
  /* 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)
  
  #define for_each_policy(__policy)			\
  	list_for_each_entry(__policy, &cpufreq_policy_list, policy_list)
  
  /* Iterate over governors */
  static LIST_HEAD(cpufreq_governor_list);
  #define for_each_governor(__governor)				\
  	list_for_each_entry(__governor, &cpufreq_governor_list, governor_list)
  
  /**
   * 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);
  
  /* 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 int cpufreq_start_governor(struct cpufreq_policy *policy);
  static void cpufreq_stop_governor(struct cpufreq_policy *policy);
  static void cpufreq_governor_limits(struct cpufreq_policy *policy);
  
  /**
   * 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);
  static struct srcu_notifier_head cpufreq_transition_notifier_list;
  
  static bool init_cpufreq_transition_notifier_list_called;
  static int __init init_cpufreq_transition_notifier_list(void)
  {
  	srcu_init_notifier_head(&cpufreq_transition_notifier_list);
  	init_cpufreq_transition_notifier_list_called = true;
  	return 0;
  }
  pure_initcall(init_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);
  
  bool cpufreq_driver_is_slow(void)
  {
  	return !(cpufreq_driver->flags & CPUFREQ_DRIVER_FAST);
  }
  EXPORT_SYMBOL_GPL(cpufreq_driver_is_slow);
  
  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)
  {
  	u64 idle_time;
  	u64 cur_wall_time;
  	u64 busy_time;
  
  	cur_wall_time = jiffies64_to_nsecs(get_jiffies_64());
  
  	busy_time = kcpustat_cpu(cpu).cpustat[CPUTIME_USER];
  	busy_time += kcpustat_cpu(cpu).cpustat[CPUTIME_SYSTEM];
  	busy_time += kcpustat_cpu(cpu).cpustat[CPUTIME_IRQ];
  	busy_time += kcpustat_cpu(cpu).cpustat[CPUTIME_SOFTIRQ];
  	busy_time += kcpustat_cpu(cpu).cpustat[CPUTIME_STEAL];
  	busy_time += kcpustat_cpu(cpu).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
   */
  int cpufreq_generic_init(struct cpufreq_policy *policy,
  		struct cpufreq_frequency_table *table,
  		unsigned int transition_latency)
  {
  	int ret;
  
  	ret = cpufreq_table_validate_and_show(policy, table);
  	if (ret) {
  		pr_err("%s: invalid frequency table: %d\n", __func__, ret);
  		return ret;
  	}
  
  	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);
  
  	return 0;
  }
  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: returns policy for a cpu and marks it busy.
   *
   * @cpu: cpu to find policy for.
   *
   * This returns policy for 'cpu', returns NULL if it doesn't exist.
   * It also increments the kobject reference count to mark it busy and so would
   * require a corresponding call to cpufreq_cpu_put() to decrement it back.
   * If corresponding call cpufreq_cpu_put() isn't made, the policy wouldn't be
   * freed as that depends on the kobj count.
   *
   * Return: A valid policy on success, otherwise NULL on failure.
   */
  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: Decrements the usage count of a policy
   *
   * @policy: policy earlier returned by cpufreq_cpu_get().
   *
   * This decrements the kobject reference count incremented earlier by calling
   * cpufreq_cpu_get().
   */
  void cpufreq_cpu_put(struct cpufreq_policy *policy)
  {
  	kobject_put(&policy->kobj);
  }
  EXPORT_SYMBOL_GPL(cpufreq_cpu_put);
  
  /*********************************************************************
   *            EXTERNALLY AFFECTING FREQUENCY CHANGES                 *
   *********************************************************************/
  
  /**
   * adjust_jiffies - adjust the system "loops_per_jiffy"
   *
   * 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
  }
  
  /*********************************************************************
   *               FREQUENCY INVARIANT CPU CAPACITY                    *
   *********************************************************************/
  
  static DEFINE_PER_CPU(unsigned long, freq_scale) = SCHED_CAPACITY_SCALE;
  static DEFINE_PER_CPU(unsigned long, max_freq_cpu);
  static DEFINE_PER_CPU(unsigned long, max_freq_scale) = SCHED_CAPACITY_SCALE;
  static DEFINE_PER_CPU(unsigned long, min_freq_scale);
  
  static void
  scale_freq_capacity(const cpumask_t *cpus, unsigned long cur_freq,
  		    unsigned long max_freq)
  {
  	unsigned long scale = (cur_freq << SCHED_CAPACITY_SHIFT) / max_freq;
  	int cpu;
  
  	for_each_cpu(cpu, cpus) {
  		per_cpu(freq_scale, cpu) = scale;
  		per_cpu(max_freq_cpu, cpu) = max_freq;
  	}
  
  	pr_debug("cpus %*pbl cur freq/max freq %lu/%lu kHz freq scale %lu\n",
  		 cpumask_pr_args(cpus), cur_freq, max_freq, scale);
  }
  
  unsigned long cpufreq_scale_freq_capacity(struct sched_domain *sd, int cpu)
  {
  	return per_cpu(freq_scale, cpu);
  }
  
  static void
  scale_max_freq_capacity(const cpumask_t *cpus, unsigned long policy_max_freq)
  {
  	unsigned long scale, max_freq;
  	int cpu = cpumask_first(cpus);
  
  	if (cpu >= nr_cpu_ids)
  		return;
  
  	max_freq = per_cpu(max_freq_cpu, cpu);
  
  	if (!max_freq)
  		return;
  
  	scale = (policy_max_freq << SCHED_CAPACITY_SHIFT) / max_freq;
  
  	for_each_cpu(cpu, cpus)
  		per_cpu(max_freq_scale, cpu) = scale;
  
  	pr_debug("cpus %*pbl policy max freq/max freq %lu/%lu kHz max freq scale %lu\n",
  		 cpumask_pr_args(cpus), policy_max_freq, max_freq, scale);
  }
  
  unsigned long cpufreq_scale_max_freq_capacity(struct sched_domain *sd, int cpu)
  {
  	return per_cpu(max_freq_scale, cpu);
  }
  
  static void
  scale_min_freq_capacity(const cpumask_t *cpus, unsigned long policy_min_freq)
  {
  	unsigned long scale, max_freq;
  	int cpu = cpumask_first(cpus);
  
  	if (cpu >= nr_cpu_ids)
  		return;
  
  	max_freq = per_cpu(max_freq_cpu, cpu);
  
  	if (!max_freq)
  		return;
  
  	scale = (policy_min_freq << SCHED_CAPACITY_SHIFT) / max_freq;
  
  	for_each_cpu(cpu, cpus)
  		per_cpu(min_freq_scale, cpu) = scale;
  
  	pr_debug("cpus %*pbl policy min freq/max freq %lu/%lu kHz min freq scale %lu\n",
  		 cpumask_pr_args(cpus), policy_min_freq, max_freq, scale);
  }
  
  unsigned long cpufreq_scale_min_freq_capacity(struct sched_domain *sd, int cpu)
  {
  	return per_cpu(min_freq_scale, cpu);
  }
  
  static void __cpufreq_notify_transition(struct cpufreq_policy *policy,
  		struct cpufreq_freqs *freqs, unsigned int state)
  {
  	BUG_ON(irqs_disabled());
  
  	if (cpufreq_disabled())
  		return;
  
  	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 (!(cpufreq_driver->flags & CPUFREQ_CONST_LOOPS)) {
  			if ((policy) && (policy->cpu == freqs->cpu) &&
  			    (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: %lu - CPU: %lu\n",
  			 (unsigned long)freqs->new, (unsigned long)freqs->cpu);
  		trace_cpu_frequency(freqs->new, freqs->cpu);
  		cpufreq_stats_record_transition(policy, freqs->new);
  		cpufreq_times_record_transition(freqs);
  		srcu_notifier_call_chain(&cpufreq_transition_notifier_list,
  				CPUFREQ_POSTCHANGE, freqs);
  		if (likely(policy) && likely(policy->cpu == freqs->cpu))
  			policy->cur = freqs->new;
  		break;
  	}
  }
  
  /**
   * cpufreq_notify_transition - call notifier chain and adjust_jiffies
   * on frequency transition.
   *
   * This function calls the transition notifiers and the "adjust_jiffies"
   * function. 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)
  {
  	for_each_cpu(freqs->cpu, policy->cpus)
  		__cpufreq_notify_transition(policy, freqs, state);
  }
  
  /* 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)
  {
  #ifdef CONFIG_SMP
  	int cpu;
  #endif
  
  	/*
  	 * 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);
  
  	scale_freq_capacity(policy->cpus, freqs->new, policy->cpuinfo.max_freq);
  #ifdef CONFIG_SMP
  	for_each_cpu(cpu, policy->cpus)
  		trace_cpu_capacity(capacity_curr_of(cpu), cpu);
  #endif
  
  	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 (unlikely(WARN_ON(!policy->transition_ongoing)))
  		return;
  
  	cpufreq_notify_post_transition(policy, freqs, transition_failed);
  
  	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("%pF\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);
  
  /**
   * cpufreq_driver_resolve_freq - Map a target frequency to a driver-supported
   * one.
   * @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)
  {
  	target_freq = clamp_val(target_freq, policy->min, policy->max);
  	policy->cached_target_freq = target_freq;
  
  	if (cpufreq_driver->target_index) {
  		int idx;
  
  		idx = cpufreq_frequency_table_target(policy, target_freq,
  						     CPUFREQ_RELATION_L);
  		policy->cached_resolved_idx = idx;
  		return policy->freq_table[idx].frequency;
  	}
  
  	if (cpufreq_driver->resolve_freq)
  		return cpufreq_driver->resolve_freq(policy, target_freq);
  
  	return target_freq;
  }
  EXPORT_SYMBOL_GPL(cpufreq_driver_resolve_freq);
  
  /*********************************************************************
   *                          SYSFS INTERFACE                          *
   *********************************************************************/
  static ssize_t show_boost(struct kobject *kobj,
  				 struct attribute *attr, char *buf)
  {
  	return sprintf(buf, "%d\n", cpufreq_driver->boost_enabled);
  }
  
  static ssize_t store_boost(struct kobject *kobj, struct 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;
  }
  
  /**
   * cpufreq_parse_governor - parse a governor string
   */
  static int cpufreq_parse_governor(char *str_governor, unsigned int *policy,
  				struct cpufreq_governor **governor)
  {
  	int err = -EINVAL;
  
  	if (cpufreq_driver->setpolicy) {
  		if (!strncasecmp(str_governor, "performance", CPUFREQ_NAME_LEN)) {
  			*policy = CPUFREQ_POLICY_PERFORMANCE;
  			err = 0;
  		} else if (!strncasecmp(str_governor, "powersave",
  						CPUFREQ_NAME_LEN)) {
  			*policy = CPUFREQ_POLICY_POWERSAVE;
  			err = 0;
  		}
  	} else {
  		struct cpufreq_governor *t;
  
  		mutex_lock(&cpufreq_governor_mutex);
  
  		t = find_governor(str_governor);
  
  		if (t == NULL) {
  			int ret;
  
  			mutex_unlock(&cpufreq_governor_mutex);
  			ret = request_module("cpufreq_%s", str_governor);
  			mutex_lock(&cpufreq_governor_mutex);
  
  			if (ret == 0)
  				t = find_governor(str_governor);
  		}
  
  		if (t != NULL) {
  			*governor = t;
  			err = 0;
  		}
  
  		mutex_unlock(&cpufreq_governor_mutex);
  	}
  	return err;
  }
  
  /**
   * 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);
  
  static ssize_t show_scaling_cur_freq(struct cpufreq_policy *policy, char *buf)
  {
  	ssize_t ret;
  
  	if (cpufreq_driver && 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;
  }
  
  static int cpufreq_set_policy(struct cpufreq_policy *policy,
  				struct cpufreq_policy *new_policy);
  
  /**
   * 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)		\
  {									\
  	int ret, temp;							\
  	struct cpufreq_policy new_policy;				\
  									\
  	memcpy(&new_policy, policy, sizeof(*policy));			\
  	new_policy.min = policy->user_policy.min;			\
  	new_policy.max = policy->user_policy.max;			\
  									\
  	ret = sscanf(buf, "%u", &new_policy.object);			\
  	if (ret != 1)							\
  		return -EINVAL;						\
  									\
  	if (new_policy.object < policy->cpuinfo.min_freq)		\
  		new_policy.object = policy->cpuinfo.min_freq;		\
  	else if (new_policy.object > policy->cpuinfo.max_freq)		\
  		new_policy.object = policy->cpuinfo.max_freq;		\
  									\
  	temp = new_policy.object;					\
  	new_policy.user_policy.object = temp;				\
  	new_policy.min = new_policy.user_policy.min;			\
  	new_policy.max = new_policy.user_policy.max;			\
  	ret = cpufreq_set_policy(policy, &new_policy);			\
  	if (!ret)							\
  		policy->user_policy.object = temp;			\
  									\
  	return ret ? ret : count;					\
  }
  
  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)
  {
  	int ret;
  	char	str_governor[16];
  	struct cpufreq_policy new_policy;
  
  	memcpy(&new_policy, policy, sizeof(*policy));
  
  	ret = sscanf(buf, "%15s", str_governor);
  	if (ret != 1)
  		return -EINVAL;
  
  	if (cpufreq_parse_governor(str_governor, &new_policy.policy,
  						&new_policy.governor))
  		return -EINVAL;
  
  	ret = cpufreq_set_policy(policy, &new_policy);
  	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;
  	}
  
  	for_each_governor(t) {
  		if (i >= (ssize_t) ((PAGE_SIZE / sizeof(char))
  		    - (CPUFREQ_NAME_LEN + 2)))
  			goto out;
  		i += scnprintf(&buf[i], CPUFREQ_NAME_PLEN, "%s ", t->name);
  	}
  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) {
  		if (i)
  			i += scnprintf(&buf[i], (PAGE_SIZE - i - 2), " ");
  		i += scnprintf(&buf[i], (PAGE_SIZE - i - 2), "%u", cpu);
  		if (i >= (PAGE_SIZE - 5))
  			break;
  	}
  	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;
  	if (cpufreq_driver->bios_limit) {
  		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 *default_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
  };
  
  #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;
  
  	down_read(&policy->rwsem);
  	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 = -EINVAL;
  
  	get_online_cpus();
  
  	if (cpu_online(policy->cpu)) {
  		down_write(&policy->rwsem);
  		ret = fattr->store(policy, buf, count);
  		up_write(&policy->rwsem);
  	}
  
  	put_online_cpus();
  
  	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_attrs	= default_attrs,
  	.release	= cpufreq_sysfs_release,
  };
  
  static void add_cpu_dev_symlink(struct cpufreq_policy *policy, unsigned int cpu)
  {
  	struct device *dev = get_cpu_device(cpu);
  
  	if (!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,
  				   struct device *dev)
  {
  	dev_dbg(dev, "%s: Removing symlink\n", __func__);
  	sysfs_remove_link(&dev->kobj, "cpufreq");
  }
  
  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;
  }
  
  __weak struct cpufreq_governor *cpufreq_default_governor(void)
  {
  	return NULL;
  }
  
  static int cpufreq_init_policy(struct cpufreq_policy *policy)
  {
  	struct cpufreq_governor *gov = NULL;
  	struct cpufreq_policy new_policy;
  
  	memcpy(&new_policy, policy, sizeof(*policy));
  
  	/* Update governor of new_policy to the governor used before hotplug */
  	gov = find_governor(policy->last_governor);
  	if (gov) {
  		pr_debug("Restoring governor %s for cpu %d\n",
  				policy->governor->name, policy->cpu);
  	} else {
  		gov = cpufreq_default_governor();
  		if (!gov)
  			return -ENODATA;
  	}
  
  	new_policy.governor = gov;
  
  	/* Use the default policy if there is no last_policy. */
  	if (cpufreq_driver->setpolicy) {
  		if (policy->last_policy)
  			new_policy.policy = policy->last_policy;
  		else
  			cpufreq_parse_governor(gov->name, &new_policy.policy,
  					       NULL);
  	}
  	/* set default policy */
  	return cpufreq_set_policy(policy, &new_policy);
  }
  
  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;
  }
  
  static void handle_update(struct work_struct *work)
  {
  	struct cpufreq_policy *policy =
  		container_of(work, struct cpufreq_policy, update);
  	unsigned int cpu = policy->cpu;
  	pr_debug("handle_update for cpu %u called\n", cpu);
  	cpufreq_update_policy(cpu);
  }
  
  static struct cpufreq_policy *cpufreq_policy_alloc(unsigned int cpu)
  {
  	struct cpufreq_policy *policy;
  	int ret;
  
  	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) {
  		pr_err("%s: failed to init policy->kobj: %d\n", __func__, ret);
  		goto err_free_real_cpus;
  	}
  
  	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_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_put_kobj(struct cpufreq_policy *policy, bool notify)
  {
  	struct kobject *kobj;
  	struct completion *cmp;
  
  	if (notify)
  		blocking_notifier_call_chain(&cpufreq_policy_notifier_list,
  					     CPUFREQ_REMOVE_POLICY, policy);
  
  	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 void cpufreq_policy_free(struct cpufreq_policy *policy, bool notify)
  {
  	unsigned long flags;
  	int cpu;
  
  	/* 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);
  
  	cpufreq_policy_put_kobj(policy, notify);
  	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;
  		up_write(&policy->rwsem);
  	} else {
  		new_policy = true;
  		policy = cpufreq_policy_alloc(cpu);
  		if (!policy)
  			return -ENOMEM;
  	}
  
  	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("initialization failed\n");
  		goto out_free_policy;
  	}
  
  	down_write(&policy->rwsem);
  
  	if (new_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) {
  		policy->user_policy.min = policy->min;
  		policy->user_policy.max = policy->max;
  
  		for_each_cpu(j, policy->related_cpus) {
  			per_cpu(cpufreq_cpu_data, j) = policy;
  			add_cpu_dev_symlink(policy, j);
  		}
  	} else {
  		policy->min = policy->user_policy.min;
  		policy->max = policy->user_policy.max;
  	}
  
  	if (cpufreq_driver->get && !cpufreq_driver->setpolicy) {
  		policy->cur = cpufreq_driver->get(policy->cpu);
  		if (!policy->cur) {
  			pr_err("%s: ->get() failed\n", __func__);
  			goto out_exit_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()) {
  		/* Are we running at unknown frequency ? */
  		ret = cpufreq_frequency_table_get_index(policy, policy->cur);
  		if (ret == -EINVAL) {
  			/* Warn user and fix it */
  			pr_debug("%s: CPU%d: Running at unlisted freq: %u KHz\n",
  				__func__, policy->cpu, policy->cur);
  			ret = __cpufreq_driver_target(policy, policy->cur - 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_debug("%s: CPU%d: Unlisted initial frequency changed to: %u KHz\n",
  				__func__, policy->cpu, policy->cur);
  		}
  	}
  
  	if (new_policy) {
  		ret = cpufreq_add_dev_interface(policy);
  		if (ret)
  			goto out_exit_policy;
  
  		cpufreq_stats_create_table(policy);
  		cpufreq_times_create_policy(policy);
  		blocking_notifier_call_chain(&cpufreq_policy_notifier_list,
  				CPUFREQ_CREATE_POLICY, policy);
  
  		write_lock_irqsave(&cpufreq_driver_lock, flags);
  		list_add(&policy->policy_list, &cpufreq_policy_list);
  		write_unlock_irqrestore(&cpufreq_driver_lock, flags);
  	}
  
  	blocking_notifier_call_chain(&cpufreq_policy_notifier_list,
  				     CPUFREQ_START, policy);
  
  	ret = cpufreq_init_policy(policy);
  	if (ret) {
  		pr_err("%s: Failed to initialize policy for cpu: %d (%d)\n",
  		       __func__, cpu, ret);
  		/* cpufreq_policy_free() will notify based on this */
  		new_policy = false;
  		goto out_exit_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);
  
  	pr_debug("initialization complete\n");
  
  	return 0;
  
  out_exit_policy:
  	for_each_cpu(j, policy->real_cpus)
  		remove_cpu_dev_symlink(policy, get_cpu_device(j));
  
  	up_write(&policy->rwsem);
  
  	if (cpufreq_driver->exit)
  		cpufreq_driver->exit(policy);
  
  out_free_policy:
  	cpufreq_policy_free(policy, !new_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);
  
  	return 0;
  }
  
  static int cpufreq_offline(unsigned int cpu)
  {
  	struct cpufreq_policy *policy;
  	int ret;
  
  	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);
  	if (has_target())
  		cpufreq_stop_governor(policy);
  
  	cpumask_clear_cpu(cpu, policy->cpus);
  
  	if (policy_is_inactive(policy)) {
  		if (has_target())
  			strncpy(policy->last_governor, policy->governor->name,
  				CPUFREQ_NAME_LEN);
  		else
  			policy->last_policy = policy->policy;
  	} else if (cpu == policy->cpu) {
  		/* Nominate new CPU */
  		policy->cpu = cpumask_any(policy->cpus);
  	}
  
  	/* Start governor again for active policy */
  	if (!policy_is_inactive(policy)) {
  		if (has_target()) {
  			ret = cpufreq_start_governor(policy);
  			if (ret)
  				pr_err("%s: Failed to start governor\n", __func__);
  		}
  
  		goto unlock;
  	}
  
  	if (cpufreq_driver->stop_cpu)
  		cpufreq_driver->stop_cpu(policy);
  
  	if (has_target())
  		cpufreq_exit_governor(policy);
  
  	/*
  	 * Perform the ->exit() even during light-weight tear-down,
  	 * since this is a core component, and is essential for the
  	 * subsequent light-weight ->init() to succeed.
  	 */
  	if (cpufreq_driver->exit) {
  		cpufreq_driver->exit(policy);
  		policy->freq_table = NULL;
  	}
  
  unlock:
  	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;
  
  	if (cpu_online(cpu))
  		cpufreq_offline(cpu);
  
  	cpumask_clear_cpu(cpu, policy->real_cpus);
  	remove_cpu_dev_symlink(policy, dev);
  
  	if (cpumask_empty(policy->real_cpus))
  		cpufreq_policy_free(policy, true);
  }
  
  /**
   *	cpufreq_out_of_sync - If actual and saved CPU frequency differs, we're
   *	in deep trouble.
   *	@policy: policy managing CPUs
   *	@new_freq: CPU frequency the CPU actually runs at
   *
   *	We adjust to current frequency first, and need to clean up later.
   *	So either call to cpufreq_update_policy() or schedule 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);
  }
  
  /**
   * 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);
  
  static unsigned int __cpufreq_get(struct cpufreq_policy *policy)
  {
  	unsigned int ret_freq = 0;
  
  	if (!cpufreq_driver->get)
  		return ret_freq;
  
  	ret_freq = cpufreq_driver->get(policy->cpu);
  
  	/*
  	 * Updating inactive policies is invalid, so avoid doing that.  Also
  	 * if fast frequency switching is used with the given policy, the check
  	 * against policy->cur is pointless, so skip it in that case too.
  	 */
  	if (unlikely(policy_is_inactive(policy)) || policy->fast_switch_enabled)
  		return ret_freq;
  
  	if (ret_freq && policy->cur &&
  		!(cpufreq_driver->flags & CPUFREQ_CONST_LOOPS)) {
  		/* verify no discrepancy between actual and
  					saved value exists */
  		if (unlikely(ret_freq != policy->cur)) {
  			cpufreq_out_of_sync(policy, ret_freq);
  			schedule_work(&policy->update);
  		}
  	}
  
  	return ret_freq;
  }
  
  /**
   * 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);
  		ret_freq = __cpufreq_get(policy);
  		up_read(&policy->rwsem);
  
  		cpufreq_cpu_put(policy);
  	}
  
  	return ret_freq;
  }
  EXPORT_SYMBOL(cpufreq_get);
  
  static unsigned int cpufreq_update_current_freq(struct cpufreq_policy *policy)
  {
  	unsigned int new_freq;
  
  	new_freq = cpufreq_driver->get(policy->cpu);
  	if (!new_freq)
  		return 0;
  
  	if (!policy->cur) {
  		pr_debug("cpufreq: Driver did not initialize current freq\n");
  		policy->cur = new_freq;
  	} else if (policy->cur != new_freq && has_target()) {
  		cpufreq_out_of_sync(policy, new_freq);
  	}
  
  	return new_freq;
  }
  
  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: %p\n", __func__,
  				policy);
  	}
  
  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)) {
  		pr_warn("%s: resume after failed suspend\n", __func__);
  		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_get_current_driver - return current driver's name
   *
   *	Return the name string of the currently loaded 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 loaded cpufreq
   *	driver, or NULL if no cpufreq driver is loaded.
   */
  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 driver with cpufreq
   *	@nb: notifier function to register
   *      @list: CPUFREQ_TRANSITION_NOTIFIER or CPUFREQ_POLICY_NOTIFIER
   *
   *	Add a driver to one of two lists: either a list of drivers that
   *      are notified about clock rate changes (once before and once after
   *      the transition), or a list of drivers that are notified about
   *      changes in cpufreq policy.
   *
   *	This function may sleep, and has the same return conditions as
   *	blocking_notifier_chain_register.
   */
  int cpufreq_register_notifier(struct notifier_block *nb, unsigned int list)
  {
  	int ret;
  
  	if (cpufreq_disabled())
  		return -EINVAL;
  
  	WARN_ON(!init_cpufreq_transition_notifier_list_called);
  
  	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 driver with cpufreq
   *	@nb: notifier block to be unregistered
   *	@list: CPUFREQ_TRANSITION_NOTIFIER or CPUFREQ_POLICY_NOTIFIER
   *
   *	Remove a driver from the CPU frequency notifier list.
   *
   *	This function may sleep, and has the same return conditions 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.
   *
   * If CPUFREQ_ENTRY_INVALID 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)
  {
  	target_freq = clamp_val(target_freq, policy->min, policy->max);
  
  	return cpufreq_driver->fast_switch(policy, target_freq);
  }
  EXPORT_SYMBOL_GPL(cpufreq_driver_fast_switch);
  
  /* 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 intermediate_freq = 0;
  	unsigned int newfreq = policy->freq_table[index].frequency;
  	int retval = -EINVAL;
  	bool notify;
  
  	if (newfreq == policy->cur)
  		return 0;
  
  	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 = policy->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;
  	int index;
  
  	if (cpufreq_disabled())
  		return -ENODEV;
  
  	/* Make sure that target_freq is within supported range */
  	target_freq = clamp_val(target_freq, policy->min, policy->max);
  
  	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)
  		return 0;
  
  	/* Save last value to restore later on errors */
  	policy->restore_freq = policy->cur;
  
  	if (cpufreq_driver->target)
  		return cpufreq_driver->target(policy, target_freq, relation);
  
  	if (!cpufreq_driver->target_index)
  		return -EINVAL;
  
  	index = cpufreq_frequency_table_target(policy, target_freq, relation);
  
  	return __target_index(policy, index);
  }
  EXPORT_SYMBOL_GPL(__cpufreq_driver_target);
  
  int cpufreq_driver_target(struct cpufreq_policy *policy,
  			  unsigned int target_freq,
  			  unsigned int relation)
  {
  	int ret = -EINVAL;
  
  	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;
  
  	if (policy->governor->max_transition_latency &&
  	    policy->cpuinfo.transition_latency >
  	    policy->governor->max_transition_latency) {
  		struct cpufreq_governor *gov = cpufreq_fallback_governor();
  
  		if (gov) {
  			pr_warn("%s governor failed, too long transition latency of HW, 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;
  		}
  	}
  
  	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);
  }
  
  static 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_driver->setpolicy)
  		cpufreq_update_current_freq(policy);
  
  	if (policy->governor->start) {
  		ret = policy->governor->start(policy);
  		if (ret)
  			return ret;
  	}
  
  	if (policy->governor->limits)
  		policy->governor->limits(policy);
  
  	return 0;
  }
  
  static 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);
  	return;
  }
  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
   *
   * 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);
  
  /*
   * policy : current policy.
   * new_policy: policy to be set.
   */
  static int cpufreq_set_policy(struct cpufreq_policy *policy,
  				struct cpufreq_policy *new_policy)
  {
  	struct cpufreq_governor *old_gov;
  	int ret;
  
  	pr_debug("setting new policy for CPU %u: %u - %u kHz\n",
  		 new_policy->cpu, new_policy->min, new_policy->max);
  
  	memcpy(&new_policy->cpuinfo, &policy->cpuinfo, sizeof(policy->cpuinfo));
  
  	/*
  	* This check works well when we store new min/max freq attributes,
  	* because new_policy is a copy of policy with one field updated.
  	*/
  	if (new_policy->min > new_policy->max)
  		return -EINVAL;
  
  	/* verify the cpu speed can be set within this limit */
  	ret = cpufreq_driver->verify(new_policy);
  	if (ret)
  		return ret;
  
  	/* adjust if necessary - all reasons */
  	blocking_notifier_call_chain(&cpufreq_policy_notifier_list,
  			CPUFREQ_ADJUST, new_policy);
  
  	/*
  	 * verify the cpu speed can be set within this limit, which might be
  	 * different to the first one
  	 */
  	ret = cpufreq_driver->verify(new_policy);
  	if (ret)
  		return ret;
  
  	/* notification of the new policy */
  	blocking_notifier_call_chain(&cpufreq_policy_notifier_list,
  			CPUFREQ_NOTIFY, new_policy);
  
  	scale_max_freq_capacity(policy->cpus, policy->max);
  	scale_min_freq_capacity(policy->cpus, policy->min);
  
  	policy->min = new_policy->min;
  	policy->max = new_policy->max;
  	trace_cpu_frequency_limits(policy->max, policy->min, policy->cpu);
  
  	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_policy->policy;
  		pr_debug("setting range\n");
  		return cpufreq_driver->setpolicy(new_policy);
  	}
  
  	if (new_policy->governor == policy->governor) {
  		pr_debug("cpufreq: 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_policy->governor;
  	ret = cpufreq_init_governor(policy);
  	if (!ret) {
  		ret = cpufreq_start_governor(policy);
  		if (!ret) {
  			pr_debug("cpufreq: governor change\n");
  			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 which shall be re-evaluated
   *
   *	Useful for policy notifiers which have different necessities
   *	at different times.
   */
  int cpufreq_update_policy(unsigned int cpu)
  {
  	struct cpufreq_policy *policy = cpufreq_cpu_get(cpu);
  	struct cpufreq_policy new_policy;
  	int ret;
  
  	if (!policy)
  		return -ENODEV;
  
  	down_write(&policy->rwsem);
  
  	pr_debug("updating policy for CPU %u\n", cpu);
  	memcpy(&new_policy, policy, sizeof(*policy));
  	new_policy.min = policy->user_policy.min;
  	new_policy.max = policy->user_policy.max;
  
  	/*
  	 * BIOS might change freq behind our back
  	 * -> ask driver for current freq and notify governors about a change
  	 */
  	if (cpufreq_driver->get && !cpufreq_driver->setpolicy) {
  		if (cpufreq_suspended) {
  			ret = -EAGAIN;
  			goto unlock;
  		}
  		new_policy.cur = cpufreq_update_current_freq(policy);
  		if (WARN_ON(!new_policy.cur)) {
  			ret = -EIO;
  			goto unlock;
  		}
  	}
  
  	ret = cpufreq_set_policy(policy, &new_policy);
  
  unlock:
  	up_write(&policy->rwsem);
  
  	cpufreq_cpu_put(policy);
  	return ret;
  }
  EXPORT_SYMBOL(cpufreq_update_policy);
  
  /*********************************************************************
   *               BOOST						     *
   *********************************************************************/
  static int cpufreq_boost_set_sw(int state)
  {
  	struct cpufreq_policy *policy;
  	int ret = -EINVAL;
  
  	for_each_active_policy(policy) {
  		if (!policy->freq_table)
  			continue;
  
  		ret = cpufreq_frequency_table_cpuinfo(policy,
  						      policy->freq_table);
  		if (ret) {
  			pr_err("%s: Policy frequency update failed\n",
  			       __func__);
  			break;
  		}
  
  		down_write(&policy->rwsem);
  		policy->user_policy.max = policy->max;
  		cpufreq_governor_limits(policy);
  		up_write(&policy->rwsem);
  	}
  
  	return ret;
  }
  
  int cpufreq_boost_trigger_state(int state)
  {
  	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);
  
  	ret = cpufreq_driver->set_boost(state);
  	if (ret) {
  		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 likely(cpufreq_driver) && 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;
  
  	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))
  		return -EINVAL;
  
  	pr_debug("trying to register driver %s\n", driver_data->name);
  
  	/* Protect against concurrent CPU online/offline. */
  	get_online_cpus();
  
  	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);
  
  	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 (!(cpufreq_driver->flags & CPUFREQ_STICKY) &&
  	    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(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:
  	put_online_cpus();
  	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 */
  	get_online_cpus();
  	subsys_interface_unregister(&cpufreq_interface);
  	remove_boost_sysfs_file();
  	cpuhp_remove_state_nocalls(hp_online);
  
  	write_lock_irqsave(&cpufreq_driver_lock, flags);
  
  	cpufreq_driver = NULL;
  
  	write_unlock_irqrestore(&cpufreq_driver_lock, flags);
  	put_online_cpus();
  
  	return 0;
  }
  EXPORT_SYMBOL_GPL(cpufreq_unregister_driver);
  
  /*
   * Stop cpufreq at shutdown to make sure it isn't holding any locks
   * or mutexes when secondary CPUs are halted.
   */
  static struct syscore_ops cpufreq_syscore_ops = {
  	.shutdown = cpufreq_suspend,
  };
  
  struct kobject *cpufreq_global_kobject;
  EXPORT_SYMBOL(cpufreq_global_kobject);
  
  static int __init cpufreq_core_init(void)
  {
  	if (cpufreq_disabled())
  		return -ENODEV;
  
  	cpufreq_global_kobject = kobject_create_and_add("cpufreq", &cpu_subsys.dev_root->kobj);
  	BUG_ON(!cpufreq_global_kobject);
  
  	register_syscore_ops(&cpufreq_syscore_ops);
  
  	return 0;
  }
  core_initcall(cpufreq_core_init);
  