Merge master.kernel.org:/pub/scm/linux/kernel/git/davem/net-2.6
[firefly-linux-kernel-4.4.55.git] / drivers / cpufreq / cpufreq.c
index 9582de1c9cadc543517b1aff92d8a7910960a7eb..d35a9f06ab7b6fe25420c53dd657e849fc00cbed 100644 (file)
@@ -5,7 +5,9 @@
  *            (C) 2002 - 2003 Dominik Brodowski <linux@brodo.de>
  *
  *  Oct 2005 - Ashok Raj <ashok.raj@intel.com>
- *                     Added handling for CPU hotplug
+ *     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
@@ -13,7 +15,6 @@
  *
  */
 
-#include <linux/config.h>
 #include <linux/kernel.h>
 #include <linux/module.h>
 #include <linux/init.h>
@@ -31,7 +32,7 @@
 #define dprintk(msg...) cpufreq_debug_printk(CPUFREQ_DEBUG_CORE, "cpufreq-core", msg)
 
 /**
- * The "cpufreq driver" - the arch- or hardware-dependend low
+ * 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.
  */
@@ -44,15 +45,14 @@ static int __cpufreq_governor(struct cpufreq_policy *policy, unsigned int event)
 static void handle_update(void *data);
 
 /**
- * Two notifier lists: the "policy" list is involved in the 
- * validation process for a new CPU frequency policy; the 
+ * 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 struct notifier_block *cpufreq_policy_notifier_list;
-static struct notifier_block *cpufreq_transition_notifier_list;
-static DECLARE_RWSEM (cpufreq_notifier_rwsem);
+static BLOCKING_NOTIFIER_HEAD(cpufreq_policy_notifier_list);
+static BLOCKING_NOTIFIER_HEAD(cpufreq_transition_notifier_list);
 
 
 static LIST_HEAD(cpufreq_governor_list);
@@ -151,7 +151,7 @@ void cpufreq_debug_printk(unsigned int type, const char *prefix, const char *fmt
        va_list args;
        unsigned int len;
        unsigned long flags;
-       
+
        WARN_ON(!prefix);
        if (type & debug) {
                spin_lock_irqsave(&disable_ratelimit_lock, flags);
@@ -198,7 +198,7 @@ static inline void cpufreq_debug_disable_ratelimit(void) { return; }
  *
  * 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 
+ * systems as each CPU might be scaled differently. So, use the arch
  * per-CPU loops_per_jiffy value wherever possible.
  */
 #ifndef CONFIG_SMP
@@ -233,7 +233,7 @@ static inline void adjust_jiffies(unsigned long val, struct cpufreq_freqs *ci) {
  *
  * This function calls the transition notifiers and the "adjust_jiffies"
  * function. It is called twice on all CPU frequency changes that have
- * external effects. 
+ * external effects.
  */
 void cpufreq_notify_transition(struct cpufreq_freqs *freqs, unsigned int state)
 {
@@ -245,39 +245,36 @@ void cpufreq_notify_transition(struct cpufreq_freqs *freqs, unsigned int state)
        dprintk("notification %u of frequency transition to %u kHz\n",
                state, freqs->new);
 
-       down_read(&cpufreq_notifier_rwsem);
-
        policy = cpufreq_cpu_data[freqs->cpu];
        switch (state) {
 
        case CPUFREQ_PRECHANGE:
-               /* detect if the driver reported a value as "old frequency" 
+               /* 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)) {
-                               dprintk(KERN_WARNING "Warning: CPU frequency is"
+                               dprintk("Warning: CPU frequency is"
                                        " %u, cpufreq assumed %u kHz.\n",
                                        freqs->old, policy->cur);
                                freqs->old = policy->cur;
                        }
                }
-               notifier_call_chain(&cpufreq_transition_notifier_list,
-                                       CPUFREQ_PRECHANGE, freqs);
+               blocking_notifier_call_chain(&cpufreq_transition_notifier_list,
+                               CPUFREQ_PRECHANGE, freqs);
                adjust_jiffies(CPUFREQ_PRECHANGE, freqs);
                break;
 
        case CPUFREQ_POSTCHANGE:
                adjust_jiffies(CPUFREQ_POSTCHANGE, freqs);
-               notifier_call_chain(&cpufreq_transition_notifier_list,
-                                       CPUFREQ_POSTCHANGE, freqs);
+               blocking_notifier_call_chain(&cpufreq_transition_notifier_list,
+                               CPUFREQ_POSTCHANGE, freqs);
                if (likely(policy) && likely(policy->cpu == freqs->cpu))
                        policy->cur = freqs->new;
                break;
        }
-       up_read(&cpufreq_notifier_rwsem);
 }
 EXPORT_SYMBOL_GPL(cpufreq_notify_transition);
 
@@ -287,41 +284,70 @@ EXPORT_SYMBOL_GPL(cpufreq_notify_transition);
  *                          SYSFS INTERFACE                          *
  *********************************************************************/
 
+static struct cpufreq_governor *__find_governor(const char *str_governor)
+{
+       struct cpufreq_governor *t;
+
+       list_for_each_entry(t, &cpufreq_governor_list, governor_list)
+               if (!strnicmp(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)
-               return -EINVAL;
+               goto out;
+
        if (cpufreq_driver->setpolicy) {
                if (!strnicmp(str_governor, "performance", CPUFREQ_NAME_LEN)) {
                        *policy = CPUFREQ_POLICY_PERFORMANCE;
-                       return 0;
+                       err = 0;
                } else if (!strnicmp(str_governor, "powersave", CPUFREQ_NAME_LEN)) {
                        *policy = CPUFREQ_POLICY_POWERSAVE;
-                       return 0;
+                       err = 0;
                }
-               return -EINVAL;
-       } else {
+       } else if (cpufreq_driver->target) {
                struct cpufreq_governor *t;
+
                mutex_lock(&cpufreq_governor_mutex);
-               if (!cpufreq_driver || !cpufreq_driver->target)
-                       goto out;
-               list_for_each_entry(t, &cpufreq_governor_list, governor_list) {
-                       if (!strnicmp(str_governor,t->name,CPUFREQ_NAME_LEN)) {
-                               *governor = t;
+
+               t = __find_governor(str_governor);
+
+               if (t == NULL) {
+                       char *name = kasprintf(GFP_KERNEL, "cpufreq_%s", str_governor);
+
+                       if (name) {
+                               int ret;
+
                                mutex_unlock(&cpufreq_governor_mutex);
-                               return 0;
+                               ret = request_module(name);
+                               mutex_lock(&cpufreq_governor_mutex);
+
+                               if (ret == 0)
+                                       t = __find_governor(str_governor);
                        }
+
+                       kfree(name);
                }
-out:
+
+               if (t != NULL) {
+                       *governor = t;
+                       err = 0;
+               }
+
                mutex_unlock(&cpufreq_governor_mutex);
        }
-       return -EINVAL;
+  out:
+       return err;
 }
-EXPORT_SYMBOL_GPL(cpufreq_parse_governor);
 
 
 /* drivers/base/cpu.c */
@@ -335,11 +361,11 @@ extern struct sysdev_class cpu_sysdev_class;
  * "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);                   \
+#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);
@@ -348,6 +374,8 @@ show_one(scaling_min_freq, min);
 show_one(scaling_max_freq, max);
 show_one(scaling_cur_freq, cur);
 
+static int __cpufreq_set_policy(struct cpufreq_policy *data, struct cpufreq_policy *policy);
+
 /**
  * cpufreq_per_cpu_attr_write() / store_##file_name() - sysfs write access
  */
@@ -366,7 +394,12 @@ static ssize_t store_##file_name                                   \
        if (ret != 1)                                                   \
                return -EINVAL;                                         \
                                                                        \
-       ret = cpufreq_set_policy(&new_policy);                          \
+       lock_cpu_hotplug();                                             \
+       mutex_lock(&policy->lock);                                      \
+       ret = __cpufreq_set_policy(policy, &new_policy);                \
+       policy->user_policy.object = policy->object;                    \
+       mutex_unlock(&policy->lock);                                    \
+       unlock_cpu_hotplug();                                           \
                                                                        \
        return ret ? ret : count;                                       \
 }
@@ -404,8 +437,8 @@ static ssize_t show_scaling_governor (struct cpufreq_policy * policy, char *buf)
 /**
  * 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) 
+static ssize_t store_scaling_governor (struct cpufreq_policy * policy,
+                                      const char *buf, size_t count)
 {
        unsigned int ret = -EINVAL;
        char    str_governor[16];
@@ -422,7 +455,19 @@ static ssize_t store_scaling_governor (struct cpufreq_policy * policy,
        if (cpufreq_parse_governor(str_governor, &new_policy.policy, &new_policy.governor))
                return -EINVAL;
 
-       ret = cpufreq_set_policy(&new_policy);
+       lock_cpu_hotplug();
+
+       /* Do not use cpufreq_set_policy here or the user_policy.max
+          will be wrongly overridden */
+       mutex_lock(&policy->lock);
+       ret = __cpufreq_set_policy(policy, &new_policy);
+
+       policy->user_policy.policy = policy->policy;
+       policy->user_policy.governor = policy->governor;
+       mutex_unlock(&policy->lock);
+
+       unlock_cpu_hotplug();
+
        return ret ? ret : count;
 }
 
@@ -528,7 +573,7 @@ static ssize_t show(struct kobject * kobj, struct attribute * attr ,char * buf)
        return ret;
 }
 
-static ssize_t store(struct kobject * kobj, struct attribute * attr, 
+static ssize_t store(struct kobject * kobj, struct attribute * attr,
                     const char * buf, size_t count)
 {
        struct cpufreq_policy * policy = to_policy(kobj);
@@ -564,7 +609,7 @@ static struct kobj_type ktype_cpufreq = {
 /**
  * cpufreq_add_dev - add a CPU device
  *
- * Adds the cpufreq interface for a CPU device. 
+ * Adds the cpufreq interface for a CPU device.
  */
 static int cpufreq_add_dev (struct sys_device * sys_dev)
 {
@@ -573,8 +618,12 @@ static int cpufreq_add_dev (struct sys_device * sys_dev)
        struct cpufreq_policy new_policy;
        struct cpufreq_policy *policy;
        struct freq_attr **drv_attr;
+       struct sys_device *cpu_sys_dev;
        unsigned long flags;
        unsigned int j;
+#ifdef CONFIG_SMP
+       struct cpufreq_policy *managed_policy;
+#endif
 
        if (cpu_is_offline(cpu))
                return 0;
@@ -587,8 +636,7 @@ static int cpufreq_add_dev (struct sys_device * sys_dev)
         * CPU because it is in the same boat. */
        policy = cpufreq_cpu_get(cpu);
        if (unlikely(policy)) {
-               dprintk("CPU already managed, adding link\n");
-               sysfs_create_link(&sys_dev->kobj, &policy->kobj, "cpufreq");
+               cpufreq_cpu_put(policy);
                cpufreq_debug_enable_ratelimit();
                return 0;
        }
@@ -623,6 +671,32 @@ static int cpufreq_add_dev (struct sys_device * sys_dev)
                goto err_out;
        }
 
+#ifdef CONFIG_SMP
+       for_each_cpu_mask(j, policy->cpus) {
+               if (cpu == j)
+                       continue;
+
+               /* check for existing affected CPUs.  They may not be aware
+                * of it due to CPU Hotplug.
+                */
+               managed_policy = cpufreq_cpu_get(j);
+               if (unlikely(managed_policy)) {
+                       spin_lock_irqsave(&cpufreq_driver_lock, flags);
+                       managed_policy->cpus = policy->cpus;
+                       cpufreq_cpu_data[cpu] = managed_policy;
+                       spin_unlock_irqrestore(&cpufreq_driver_lock, flags);
+
+                       dprintk("CPU already managed, adding link\n");
+                       sysfs_create_link(&sys_dev->kobj,
+                                         &managed_policy->kobj, "cpufreq");
+
+                       cpufreq_debug_enable_ratelimit();
+                       mutex_unlock(&policy->lock);
+                       ret = 0;
+                       goto err_out_driver_exit; /* call driver->exit() */
+               }
+       }
+#endif
        memcpy(&new_policy, policy, sizeof(struct cpufreq_policy));
 
        /* prepare interface data */
@@ -650,12 +724,26 @@ static int cpufreq_add_dev (struct sys_device * sys_dev)
        for_each_cpu_mask(j, policy->cpus)
                cpufreq_cpu_data[j] = policy;
        spin_unlock_irqrestore(&cpufreq_driver_lock, flags);
+
+       /* symlink affected CPUs */
+       for_each_cpu_mask(j, policy->cpus) {
+               if (j == cpu)
+                       continue;
+               if (!cpu_online(j))
+                       continue;
+
+               dprintk("CPU %u already managed, adding link\n", j);
+               cpufreq_cpu_get(cpu);
+               cpu_sys_dev = get_cpu_sysdev(j);
+               sysfs_create_link(&cpu_sys_dev->kobj, &policy->kobj,
+                                 "cpufreq");
+       }
+
        policy->governor = NULL; /* to assure that the starting sequence is
                                  * run in cpufreq_set_policy */
        mutex_unlock(&policy->lock);
-       
+
        /* set default policy */
-       
        ret = cpufreq_set_policy(&new_policy);
        if (ret) {
                dprintk("setting policy failed\n");
@@ -665,7 +753,7 @@ static int cpufreq_add_dev (struct sys_device * sys_dev)
        module_put(cpufreq_driver->owner);
        dprintk("initialization complete\n");
        cpufreq_debug_enable_ratelimit();
-       
+
        return 0;
 
 
@@ -724,10 +812,11 @@ static int cpufreq_remove_dev (struct sys_device * sys_dev)
 
 #ifdef CONFIG_SMP
        /* if this isn't the CPU which is the parent of the kobj, we
-        * only need to unlink, put and exit 
+        * only need to unlink, put and exit
         */
        if (unlikely(cpu != data->cpu)) {
                dprintk("removing link\n");
+               cpu_clear(cpu, data->cpus);
                spin_unlock_irqrestore(&cpufreq_driver_lock, flags);
                sysfs_remove_link(&sys_dev->kobj, "cpufreq");
                cpufreq_cpu_put(data);
@@ -740,7 +829,7 @@ static int cpufreq_remove_dev (struct sys_device * sys_dev)
        if (!kobject_get(&data->kobj)) {
                spin_unlock_irqrestore(&cpufreq_driver_lock, flags);
                cpufreq_debug_enable_ratelimit();
-               return -EFAULT;
+               return -EFAULT;
        }
 
 #ifdef CONFIG_SMP
@@ -783,7 +872,7 @@ static int cpufreq_remove_dev (struct sys_device * sys_dev)
        kobject_put(&data->kobj);
 
        /* we need to make sure that the underlying kobj is actually
-        * not referenced anymore by anybody before we proceed with 
+        * not referenced anymore by anybody before we proceed with
         * unloading.
         */
        dprintk("waiting for dropping of refcount\n");
@@ -820,7 +909,7 @@ static void cpufreq_out_of_sync(unsigned int cpu, unsigned int old_freq, unsigne
 {
        struct cpufreq_freqs freqs;
 
-       dprintk(KERN_WARNING "Warning: CPU frequency out of sync: cpufreq and timing "
+       dprintk("Warning: CPU frequency out of sync: cpufreq and timing "
               "core thinks of %u, is %u kHz.\n", old_freq, new_freq);
 
        freqs.cpu = cpu;
@@ -831,7 +920,7 @@ static void cpufreq_out_of_sync(unsigned int cpu, unsigned int old_freq, unsigne
 }
 
 
-/** 
+/**
  * cpufreq_quick_get - get the CPU frequency (in kHz) frpm policy->cur
  * @cpu: CPU number
  *
@@ -855,7 +944,7 @@ unsigned int cpufreq_quick_get(unsigned int cpu)
 EXPORT_SYMBOL(cpufreq_quick_get);
 
 
-/** 
+/**
  * cpufreq_get - get the current CPU frequency (in kHz)
  * @cpu: CPU number
  *
@@ -952,7 +1041,7 @@ static int cpufreq_suspend(struct sys_device * sysdev, pm_message_t pmsg)
                struct cpufreq_freqs freqs;
 
                if (!(cpufreq_driver->flags & CPUFREQ_PM_NO_WARN))
-                       dprintk(KERN_DEBUG "Warning: CPU frequency is %u, "
+                       dprintk("Warning: CPU frequency is %u, "
                               "cpufreq assumed %u kHz.\n",
                               cur_freq, cpu_policy->cur);
 
@@ -960,7 +1049,7 @@ static int cpufreq_suspend(struct sys_device * sysdev, pm_message_t pmsg)
                freqs.old = cpu_policy->cur;
                freqs.new = cur_freq;
 
-               notifier_call_chain(&cpufreq_transition_notifier_list,
+               blocking_notifier_call_chain(&cpufreq_transition_notifier_list,
                                    CPUFREQ_SUSPENDCHANGE, &freqs);
                adjust_jiffies(CPUFREQ_SUSPENDCHANGE, &freqs);
 
@@ -1033,7 +1122,7 @@ static int cpufreq_resume(struct sys_device * sysdev)
                        struct cpufreq_freqs freqs;
 
                        if (!(cpufreq_driver->flags & CPUFREQ_PM_NO_WARN))
-                               dprintk(KERN_WARNING "Warning: CPU frequency"
+                               dprintk("Warning: CPU frequency"
                                       "is %u, cpufreq assumed %u kHz.\n",
                                       cur_freq, cpu_policy->cur);
 
@@ -1041,7 +1130,8 @@ static int cpufreq_resume(struct sys_device * sysdev)
                        freqs.old = cpu_policy->cur;
                        freqs.new = cur_freq;
 
-                       notifier_call_chain(&cpufreq_transition_notifier_list,
+                       blocking_notifier_call_chain(
+                                       &cpufreq_transition_notifier_list,
                                        CPUFREQ_RESUMECHANGE, &freqs);
                        adjust_jiffies(CPUFREQ_RESUMECHANGE, &freqs);
 
@@ -1072,30 +1162,30 @@ static struct sysdev_driver cpufreq_sysdev_driver = {
  *     @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 
+ *     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
- *     notifier_chain_register.
+ *     blocking_notifier_chain_register.
  */
 int cpufreq_register_notifier(struct notifier_block *nb, unsigned int list)
 {
        int ret;
 
-       down_write(&cpufreq_notifier_rwsem);
        switch (list) {
        case CPUFREQ_TRANSITION_NOTIFIER:
-               ret = notifier_chain_register(&cpufreq_transition_notifier_list, nb);
+               ret = blocking_notifier_chain_register(
+                               &cpufreq_transition_notifier_list, nb);
                break;
        case CPUFREQ_POLICY_NOTIFIER:
-               ret = notifier_chain_register(&cpufreq_policy_notifier_list, nb);
+               ret = blocking_notifier_chain_register(
+                               &cpufreq_policy_notifier_list, nb);
                break;
        default:
                ret = -EINVAL;
        }
-       up_write(&cpufreq_notifier_rwsem);
 
        return ret;
 }
@@ -1110,24 +1200,24 @@ EXPORT_SYMBOL(cpufreq_register_notifier);
  *     Remove a driver from the CPU frequency notifier list.
  *
  *     This function may sleep, and has the same return conditions as
- *     notifier_chain_unregister.
+ *     blocking_notifier_chain_unregister.
  */
 int cpufreq_unregister_notifier(struct notifier_block *nb, unsigned int list)
 {
        int ret;
 
-       down_write(&cpufreq_notifier_rwsem);
        switch (list) {
        case CPUFREQ_TRANSITION_NOTIFIER:
-               ret = notifier_chain_unregister(&cpufreq_transition_notifier_list, nb);
+               ret = blocking_notifier_chain_unregister(
+                               &cpufreq_transition_notifier_list, nb);
                break;
        case CPUFREQ_POLICY_NOTIFIER:
-               ret = notifier_chain_unregister(&cpufreq_policy_notifier_list, nb);
+               ret = blocking_notifier_chain_unregister(
+                               &cpufreq_policy_notifier_list, nb);
                break;
        default:
                ret = -EINVAL;
        }
-       up_write(&cpufreq_notifier_rwsem);
 
        return ret;
 }
@@ -1139,20 +1229,18 @@ EXPORT_SYMBOL(cpufreq_unregister_notifier);
  *********************************************************************/
 
 
+/* Must be called with lock_cpu_hotplug held */
 int __cpufreq_driver_target(struct cpufreq_policy *policy,
                            unsigned int target_freq,
                            unsigned int relation)
 {
        int retval = -EINVAL;
 
-       lock_cpu_hotplug();
        dprintk("target for CPU %u: %u kHz, relation %u\n", policy->cpu,
                target_freq, relation);
        if (cpu_online(policy->cpu) && cpufreq_driver->target)
                retval = cpufreq_driver->target(policy, target_freq, relation);
 
-       unlock_cpu_hotplug();
-
        return retval;
 }
 EXPORT_SYMBOL_GPL(__cpufreq_driver_target);
@@ -1167,17 +1255,23 @@ int cpufreq_driver_target(struct cpufreq_policy *policy,
        if (!policy)
                return -EINVAL;
 
+       lock_cpu_hotplug();
        mutex_lock(&policy->lock);
 
        ret = __cpufreq_driver_target(policy, target_freq, relation);
 
        mutex_unlock(&policy->lock);
+       unlock_cpu_hotplug();
 
        cpufreq_cpu_put(policy);
        return ret;
 }
 EXPORT_SYMBOL_GPL(cpufreq_driver_target);
 
+/*
+ * Locking: Must be called with the lock_cpu_hotplug() lock held
+ * when "event" is CPUFREQ_GOV_LIMITS
+ */
 
 static int __cpufreq_governor(struct cpufreq_policy *policy, unsigned int event)
 {
@@ -1199,43 +1293,23 @@ static int __cpufreq_governor(struct cpufreq_policy *policy, unsigned int event)
 }
 
 
-int cpufreq_governor(unsigned int cpu, unsigned int event)
-{
-       int ret = 0;
-       struct cpufreq_policy *policy = cpufreq_cpu_get(cpu);
-
-       if (!policy)
-               return -EINVAL;
-
-       mutex_lock(&policy->lock);
-       ret = __cpufreq_governor(policy, event);
-       mutex_unlock(&policy->lock);
-
-       cpufreq_cpu_put(policy);
-       return ret;
-}
-EXPORT_SYMBOL_GPL(cpufreq_governor);
-
-
 int cpufreq_register_governor(struct cpufreq_governor *governor)
 {
-       struct cpufreq_governor *t;
+       int err;
 
        if (!governor)
                return -EINVAL;
 
        mutex_lock(&cpufreq_governor_mutex);
-       
-       list_for_each_entry(t, &cpufreq_governor_list, governor_list) {
-               if (!strnicmp(governor->name,t->name,CPUFREQ_NAME_LEN)) {
-                       mutex_unlock(&cpufreq_governor_mutex);
-                       return -EBUSY;
-               }
+
+       err = -EBUSY;
+       if (__find_governor(governor->name) == NULL) {
+               err = 0;
+               list_add(&governor->governor_list, &cpufreq_governor_list);
        }
-       list_add(&governor->governor_list, &cpufreq_governor_list);
 
-       mutex_unlock(&cpufreq_governor_mutex);
-       return 0;
+       mutex_unlock(&cpufreq_governor_mutex);
+       return err;
 }
 EXPORT_SYMBOL_GPL(cpufreq_register_governor);
 
@@ -1284,6 +1358,9 @@ int cpufreq_get_policy(struct cpufreq_policy *policy, unsigned int cpu)
 EXPORT_SYMBOL(cpufreq_get_policy);
 
 
+/*
+ * Locking: Must be called with the lock_cpu_hotplug() lock held
+ */
 static int __cpufreq_set_policy(struct cpufreq_policy *data, struct cpufreq_policy *policy)
 {
        int ret = 0;
@@ -1294,34 +1371,33 @@ static int __cpufreq_set_policy(struct cpufreq_policy *data, struct cpufreq_poli
 
        memcpy(&policy->cpuinfo, &data->cpuinfo, sizeof(struct cpufreq_cpuinfo));
 
+       if (policy->min > data->min && policy->min > policy->max) {
+               ret = -EINVAL;
+               goto error_out;
+       }
+
        /* verify the cpu speed can be set within this limit */
        ret = cpufreq_driver->verify(policy);
        if (ret)
                goto error_out;
 
-       down_read(&cpufreq_notifier_rwsem);
-
        /* adjust if necessary - all reasons */
-       notifier_call_chain(&cpufreq_policy_notifier_list, CPUFREQ_ADJUST,
-                           policy);
+       blocking_notifier_call_chain(&cpufreq_policy_notifier_list,
+                       CPUFREQ_ADJUST, policy);
 
        /* adjust if necessary - hardware incompatibility*/
-       notifier_call_chain(&cpufreq_policy_notifier_list, CPUFREQ_INCOMPATIBLE,
-                           policy);
+       blocking_notifier_call_chain(&cpufreq_policy_notifier_list,
+                       CPUFREQ_INCOMPATIBLE, policy);
 
        /* verify the cpu speed can be set within this limit,
           which might be different to the first one */
        ret = cpufreq_driver->verify(policy);
-       if (ret) {
-               up_read(&cpufreq_notifier_rwsem);
+       if (ret)
                goto error_out;
-       }
 
        /* notification of the new policy */
-       notifier_call_chain(&cpufreq_policy_notifier_list, CPUFREQ_NOTIFY,
-                           policy);
-
-       up_read(&cpufreq_notifier_rwsem);
+       blocking_notifier_call_chain(&cpufreq_policy_notifier_list,
+                       CPUFREQ_NOTIFY, policy);
 
        data->min = policy->min;
        data->max = policy->max;
@@ -1384,6 +1460,8 @@ int cpufreq_set_policy(struct cpufreq_policy *policy)
        if (!data)
                return -EINVAL;
 
+       lock_cpu_hotplug();
+
        /* lock this CPU */
        mutex_lock(&data->lock);
 
@@ -1394,6 +1472,8 @@ int cpufreq_set_policy(struct cpufreq_policy *policy)
        data->user_policy.governor = data->governor;
 
        mutex_unlock(&data->lock);
+
+       unlock_cpu_hotplug();
        cpufreq_cpu_put(data);
 
        return ret;
@@ -1417,6 +1497,7 @@ int cpufreq_update_policy(unsigned int cpu)
        if (!data)
                return -ENODEV;
 
+       lock_cpu_hotplug();
        mutex_lock(&data->lock);
 
        dprintk("updating policy for CPU %u\n", cpu);
@@ -1442,13 +1523,14 @@ int cpufreq_update_policy(unsigned int cpu)
        ret = __cpufreq_set_policy(data, &policy);
 
        mutex_unlock(&data->lock);
-
+       unlock_cpu_hotplug();
        cpufreq_cpu_put(data);
        return ret;
 }
 EXPORT_SYMBOL(cpufreq_update_policy);
 
-static int __cpuinit cpufreq_cpu_callback(struct notifier_block *nfb,
+#ifdef CONFIG_HOTPLUG_CPU
+static int cpufreq_cpu_callback(struct notifier_block *nfb,
                                        unsigned long action, void *hcpu)
 {
        unsigned int cpu = (unsigned long)hcpu;
@@ -1483,10 +1565,11 @@ static int __cpuinit cpufreq_cpu_callback(struct notifier_block *nfb,
        return NOTIFY_OK;
 }
 
-static struct notifier_block cpufreq_cpu_notifier =
+static struct notifier_block __cpuinitdata cpufreq_cpu_notifier =
 {
     .notifier_call = cpufreq_cpu_callback,
 };
+#endif /* CONFIG_HOTPLUG_CPU */
 
 /*********************************************************************
  *               REGISTER / UNREGISTER CPUFREQ DRIVER                *
@@ -1497,9 +1580,9 @@ static struct notifier_block cpufreq_cpu_notifier =
  * @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 
+ *   Registers a CPU Frequency driver to this core code. This code
  * returns zero on success, -EBUSY when another driver got here first
- * (and isn't unregistered in the meantime). 
+ * (and isn't unregistered in the meantime).
  *
  */
 int cpufreq_register_driver(struct cpufreq_driver *driver_data)
@@ -1547,7 +1630,7 @@ int cpufreq_register_driver(struct cpufreq_driver *driver_data)
        }
 
        if (!ret) {
-               register_cpu_notifier(&cpufreq_cpu_notifier);
+               register_hotcpu_notifier(&cpufreq_cpu_notifier);
                dprintk("driver %s up and running\n", driver_data->name);
                cpufreq_debug_enable_ratelimit();
        }
@@ -1560,7 +1643,7 @@ 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 
+ *    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.
@@ -1579,7 +1662,7 @@ int cpufreq_unregister_driver(struct cpufreq_driver *driver)
        dprintk("unregistering driver %s\n", driver->name);
 
        sysdev_driver_unregister(&cpu_sysdev_class, &cpufreq_sysdev_driver);
-       unregister_cpu_notifier(&cpufreq_cpu_notifier);
+       unregister_hotcpu_notifier(&cpufreq_cpu_notifier);
 
        spin_lock_irqsave(&cpufreq_driver_lock, flags);
        cpufreq_driver = NULL;