Merge bk://linux-dj.bkbits.net/cpufreq

into home.transmeta.com:/home/torvalds/v2.5/linux

Documentation/cpu-freq/core.txt

@@ -35,6 +35,10 @@ speed limits (like LCD drivers on ARM architecture). Additionally, the
 kernel "constant" loops_per_jiffy is updated on frequency changes
 here.
 
+Reference counting is done by cpufreq_get_cpu and cpufreq_put_cpu,
+which make sure that the cpufreq processor driver is correctly
+registered with the core, and will not be unloaded until
+cpufreq_put_cpu is called.
 
 2. CPUFreq notifiers
 ====================

Documentation/cpu-freq/cpu-drivers.txt

@@ -63,6 +63,9 @@ And optionally
 
 cpufreq_driver.exit -		A pointer to a per-CPU cleanup function.
 
+cpufreq_driver.attr -		A pointer to a NULL-terminated list of
+				"struct freq_attr" which allow to
+				export values to sysfs.
 
 
 1.2 Per-CPU Initialization

Documentation/cpu-freq/user-guide.txt

@@ -114,9 +114,9 @@ the processor shall run at.
 ------------------------------
 
 The preferred interface is located in the sysfs filesystem. If you
-mounted it at /sys, the cpufreq interface is located in the 
-cpu-device directory (e.g. /sys/devices/sys/cpu0/ for the first
-CPU).
+mounted it at /sys, the cpufreq interface is located in a subdirectory
+"cpufreq" within the cpu-device directory
+(e.g. /sys/devices/sys/cpu0/cpufreq/ for the first CPU).
 
 cpuinfo_min_freq :		this file shows the minimum operating
 				frequency the processor can run at(in kHz) 
@@ -125,7 +125,7 @@ cpuinfo_max_freq :		this file shows the maximum operating
 scaling_driver :		this file shows what cpufreq driver is
 				used to set the frequency on this CPU
 
-available_scaling_governors :	this file shows the CPUfreq governors
+scaling_available_governors :	this file shows the CPUfreq governors
 				available in this kernel. You can see the
 				currently activated governor in
 

arch/i386/kernel/cpu/cpufreq/acpi.c

@@ -619,6 +619,7 @@ static struct cpufreq_driver acpi_cpufreq_driver = {
 	.init		= acpi_cpufreq_cpu_init,
 	.exit		= acpi_cpufreq_cpu_exit,
 	.name		= "acpi-cpufreq",
+	.owner		= THIS_MODULE,
 };
 
 

arch/i386/kernel/cpu/cpufreq/elanfreq.c

@@ -250,6 +250,7 @@ static struct cpufreq_driver elanfreq_driver = {
 	.target 	= elanfreq_target,
 	.init		= elanfreq_cpu_init,
 	.name		= "elanfreq",
+	.owner		= THIS_MODULE,
 };
 
 

arch/i386/kernel/cpu/cpufreq/gx-suspmod.c

@@ -451,6 +451,7 @@ static struct cpufreq_driver gx_suspmod_driver = {
 	.target		= cpufreq_gx_target,
 	.init		= cpufreq_gx_cpu_init,
 	.name		= "gx-suspmod",
+	.owner		= THIS_MODULE,
 };
 
 static int __init cpufreq_gx_init(void)

arch/i386/kernel/cpu/cpufreq/longhaul.c

@@ -649,6 +649,7 @@ static struct cpufreq_driver longhaul_driver = {
 	.target 	= longhaul_target,
 	.init		= longhaul_cpu_init,
 	.name		= "longhaul",
+	.owner		= THIS_MODULE,
 };
 
 static int __init longhaul_init (void)

arch/i386/kernel/cpu/cpufreq/longrun.c

@@ -253,6 +253,7 @@ static struct cpufreq_driver longrun_driver = {
 	.setpolicy 	= longrun_set_policy,
 	.init		= longrun_cpu_init,
 	.name		= "longrun",
+	.owner		= THIS_MODULE,
 };
 
 

arch/i386/kernel/cpu/cpufreq/p4-clockmod.c

@@ -214,6 +214,7 @@ static int cpufreq_p4_cpu_init(struct cpufreq_policy *policy)
 		else
 			p4clockmod_table[i].frequency = (stock_freq * i)/8;
 	}
+	cpufreq_frequency_table_get_attr(p4clockmod_table, policy->cpu);
 	
 	/* cpuinfo and default policy values */
 	policy->policy = CPUFREQ_POLICY_PERFORMANCE;
@@ -226,9 +227,14 @@ static int cpufreq_p4_cpu_init(struct cpufreq_policy *policy)
 
 static int cpufreq_p4_cpu_exit(struct cpufreq_policy *policy)
 {
+	cpufreq_frequency_table_put_attr(policy->cpu);    
 	return cpufreq_p4_setdc(policy->cpu, DC_DISABLE);
 }
 
+static struct freq_attr* p4clockmod_attr[] = {
+	&cpufreq_freq_attr_scaling_available_freqs,
+	NULL,
+};
 
 static struct cpufreq_driver p4clockmod_driver = {
 	.verify 	= cpufreq_p4_verify,
@@ -236,6 +242,8 @@ static struct cpufreq_driver p4clockmod_driver = {
 	.init		= cpufreq_p4_cpu_init,
 	.exit		= cpufreq_p4_cpu_exit,
 	.name		= "p4-clockmod",
+	.owner		= THIS_MODULE,
+	.attr		= p4clockmod_attr,
 };
 
 

arch/i386/kernel/cpu/cpufreq/powernow-k6.c

@@ -190,6 +190,7 @@ static struct cpufreq_driver powernow_k6_driver = {
 	.init		= powernow_k6_cpu_init,
 	.exit		= powernow_k6_cpu_exit,
 	.name		= "powernow-k6",
+	.owner		= THIS_MODULE,
 };
 
 

arch/i386/kernel/cpu/cpufreq/powernow-k7.c

@@ -377,6 +377,7 @@ static struct cpufreq_driver powernow_driver = {
 	.target 	= powernow_target,
 	.init		= powernow_cpu_init,
 	.name		= "powernow-k7",
+	.owner		= THIS_MODULE,
 };
 
 static int __init powernow_init (void)

arch/i386/kernel/cpu/cpufreq/speedstep.c

@@ -29,7 +29,6 @@
 
 #include <asm/msr.h>
 
-
 /* speedstep_chipset:
  *   It is necessary to know which chipset is used. As accesses to 
  * this device occur at various places in this module, we need a 
@@ -40,7 +39,7 @@ static struct pci_dev                   *speedstep_chipset_dev;
 
 #define SPEEDSTEP_CHIPSET_ICH2M         0x00000002
 #define SPEEDSTEP_CHIPSET_ICH3M         0x00000003
-
+#define SPEEDSTEP_CHIPSET_ICH4M         0x00000004
 
 /* speedstep_processor
  */
@@ -106,6 +105,7 @@ static int speedstep_get_state (unsigned int *state)
 	switch (speedstep_chipset) {
 	case SPEEDSTEP_CHIPSET_ICH2M:
 	case SPEEDSTEP_CHIPSET_ICH3M:
+	case SPEEDSTEP_CHIPSET_ICH4M:
 		/* get PMBASE */
 		pci_read_config_dword(speedstep_chipset_dev, 0x40, &pmbase);
 		if (!(pmbase & 0x01))
@@ -166,6 +166,7 @@ static void speedstep_set_state (unsigned int state, int notify)
 	switch (speedstep_chipset) {
 	case SPEEDSTEP_CHIPSET_ICH2M:
 	case SPEEDSTEP_CHIPSET_ICH3M:
+	case SPEEDSTEP_CHIPSET_ICH4M:
 		/* get PMBASE */
 		pci_read_config_dword(speedstep_chipset_dev, 0x40, &pmbase);
 		if (!(pmbase & 0x01))
@@ -245,6 +246,7 @@ static int speedstep_activate (void)
 	switch (speedstep_chipset) {
 	case SPEEDSTEP_CHIPSET_ICH2M:
 	case SPEEDSTEP_CHIPSET_ICH3M:
+	case SPEEDSTEP_CHIPSET_ICH4M:
 	{
 		u16             value = 0;
 
@@ -276,6 +278,14 @@ static int speedstep_activate (void)
  */
 static unsigned int speedstep_detect_chipset (void)
 {
+	speedstep_chipset_dev = pci_find_subsys(PCI_VENDOR_ID_INTEL,
+			      PCI_DEVICE_ID_INTEL_82801DB_12, 
+			      PCI_ANY_ID,
+			      PCI_ANY_ID,
+			      NULL);
+	if (speedstep_chipset_dev)
+		return SPEEDSTEP_CHIPSET_ICH4M;
+
 	speedstep_chipset_dev = pci_find_subsys(PCI_VENDOR_ID_INTEL,
 			      PCI_DEVICE_ID_INTEL_82801CA_12, 
 			      PCI_ANY_ID,
@@ -658,6 +668,7 @@ static struct cpufreq_driver speedstep_driver = {
 	.verify 	= speedstep_verify,
 	.target 	= speedstep_target,
 	.init		= speedstep_cpu_init,
+	.owner		= THIS_MODULE,
 };
 
 

arch/sparc64/kernel/us3_cpufreq.c

@@ -276,6 +276,7 @@ static int __init us3freq_init(void)
 		driver->target = us3freq_target;
 		driver->init = us3freq_cpu_init;
 		driver->exit = us3freq_cpu_exit;
+		driver->owner = THIS_MODULE,
 		strcpy(driver->name, "UltraSPARC-III");
 
 		cpufreq_us3_driver = driver;

drivers/cpufreq/freq_table.c

@@ -77,56 +77,6 @@ int cpufreq_frequency_table_verify(struct cpufreq_policy *policy,
 EXPORT_SYMBOL_GPL(cpufreq_frequency_table_verify);
 
 
-int cpufreq_frequency_table_setpolicy(struct cpufreq_policy *policy,
-				      struct cpufreq_frequency_table *table,
-				      unsigned int *index)
-{
-	struct cpufreq_frequency_table optimal = { .index = ~0, };
-	unsigned int i;
-
-	switch (policy->policy) {
-	case CPUFREQ_POLICY_PERFORMANCE:
-		optimal.frequency = 0;
-		break;
-	case CPUFREQ_POLICY_POWERSAVE:
-		optimal.frequency = ~0;
-		break;
-	}
-
-	if (!cpu_online(policy->cpu))
-		return -EINVAL;
-
-	for (i=0; (table[i].frequency != CPUFREQ_TABLE_END); i++) {
-		unsigned int freq = table[i].frequency;
-		if (freq == CPUFREQ_ENTRY_INVALID)
-			continue;
-		if ((freq < policy->min) || (freq > policy->max))
-			continue;
-		switch(policy->policy) {
-		case CPUFREQ_POLICY_PERFORMANCE:
-			if (optimal.frequency <= freq) {
-				optimal.frequency = freq;
-				optimal.index = i;
-			}
-			break;
-		case CPUFREQ_POLICY_POWERSAVE:
-			if (optimal.frequency >= freq) {
-				optimal.frequency = freq;
-				optimal.index = i;
-			}
-			break;
-		}
-	}
-	if (optimal.index > i)
-		return -EINVAL;
-
-	*index = optimal.index;
-	
-	return 0;
-}
-EXPORT_SYMBOL_GPL(cpufreq_frequency_table_setpolicy);
-
-
 int cpufreq_frequency_table_target(struct cpufreq_policy *policy,
 				   struct cpufreq_frequency_table *table,
 				   unsigned int target_freq,
@@ -197,6 +147,56 @@ int cpufreq_frequency_table_target(struct cpufreq_policy *policy,
 }
 EXPORT_SYMBOL_GPL(cpufreq_frequency_table_target);
 
+static struct cpufreq_frequency_table *show_table[NR_CPUS];
+/**
+ * show_scaling_governor - show the current policy for the specified CPU
+ */
+static ssize_t show_available_freqs (struct cpufreq_policy *policy, char *buf)
+{
+	unsigned int i = 0;
+	unsigned int cpu = policy->cpu;
+	ssize_t count = 0;
+	struct cpufreq_frequency_table *table;
+
+	if (!show_table[cpu])
+		return -ENODEV;
+
+	table = show_table[cpu];
+
+	for (i=0; (table[i].frequency != CPUFREQ_TABLE_END); i++) {
+		if (table[i].frequency == CPUFREQ_ENTRY_INVALID)
+			continue;
+		count += sprintf(&buf[count], "%d ", table[i].frequency);
+	}
+	count += sprintf(&buf[count], "\n");
+
+	return count;
+
+}
+
+struct freq_attr cpufreq_freq_attr_scaling_available_freqs = {
+	.attr = { .name = "scaling_available_frequencies", .mode = 0444 },
+	.show = show_available_freqs,
+};
+EXPORT_SYMBOL_GPL(cpufreq_freq_attr_scaling_available_freqs);
+
+/*
+ * if you use these, you must assure that the frequency table is valid
+ * all the time between get_attr and put_attr!
+ */
+void cpufreq_frequency_table_get_attr(struct cpufreq_frequency_table *table, 
+				      unsigned int cpu)
+{
+	show_table[cpu] = table;
+}
+EXPORT_SYMBOL_GPL(cpufreq_frequency_table_get_attr);
+
+void cpufreq_frequency_table_put_attr(unsigned int cpu)
+{
+	show_table[cpu] = NULL;
+}
+EXPORT_SYMBOL_GPL(cpufreq_frequency_table_put_attr);
+
 
 MODULE_AUTHOR ("Dominik Brodowski <linux@brodo.de>");
 MODULE_DESCRIPTION ("CPUfreq frequency table helpers");

drivers/cpufreq/userspace.c

@@ -23,6 +23,7 @@
 #include <linux/sysctl.h>
 #include <linux/types.h>
 #include <linux/fs.h>
+#include <linux/sysfs.h>
 
 #include <asm/uaccess.h>
 
@@ -112,7 +113,7 @@ int cpufreq_set(unsigned int freq, unsigned int cpu)
 	if (freq > cpu_max_freq[cpu])
 		freq = cpu_max_freq[cpu];
 
-	ret = cpufreq_driver_target_l(&current_policy[cpu], freq, 
+	ret = cpufreq_driver_target(&current_policy[cpu], freq, 
 	      CPUFREQ_RELATION_L);
 
  err:
@@ -465,23 +466,14 @@ static inline void cpufreq_sysctl_exit(void)
 
 
 /************************** sysfs interface ************************/
-static inline int to_cpu_nr (struct device *dev)
+static ssize_t show_speed (struct cpufreq_policy *policy, char *buf)
 {
-	struct sys_device * cpu_sys_dev = container_of(dev, struct sys_device, dev);
-	return (cpu_sys_dev->id);
-}
-
-static ssize_t show_speed (struct device *dev, char *buf)
-{
-	unsigned int cpu = to_cpu_nr(dev);
-
-	return sprintf (buf, "%u\n", cpu_cur_freq[cpu]);
+	return sprintf (buf, "%u\n", cpu_cur_freq[policy->cpu]);
 }
 
 static ssize_t 
-store_speed (struct device *dev, const char *buf, size_t count) 
+store_speed (struct cpufreq_policy *policy, const char *buf, size_t count) 
 {
-	unsigned int cpu = to_cpu_nr(dev);
 	unsigned int freq = 0;
 	unsigned int ret;
 
@@ -489,13 +481,16 @@ store_speed (struct device *dev, const char *buf, size_t count)
 	if (ret != 1)
 		return -EINVAL;
 
-	cpufreq_set(freq, cpu);
+	cpufreq_set(freq, policy->cpu);
 
 	return count;
 }
 
-static DEVICE_ATTR(scaling_setspeed, (S_IRUGO | S_IWUSR), show_speed, store_speed);
-
+static struct freq_attr freq_attr_scaling_setspeed = {
+	.attr = { .name = "scaling_setspeed", .mode = 0644 },
+	.show = show_speed,
+	.store = store_speed,
+};
 
 static int cpufreq_governor_userspace(struct cpufreq_policy *policy,
 				   unsigned int event)
@@ -511,7 +506,7 @@ static int cpufreq_governor_userspace(struct cpufreq_policy *policy,
 		cpu_min_freq[cpu] = policy->min;
 		cpu_max_freq[cpu] = policy->max;
 		cpu_cur_freq[cpu] = policy->cur;
-		device_create_file (policy->dev, &dev_attr_scaling_setspeed);
+		sysfs_create_file (&policy->kobj, &freq_attr_scaling_setspeed.attr);
 		memcpy (&current_policy[cpu], policy, sizeof(struct cpufreq_policy));
 		up(&userspace_sem);
 		break;
@@ -520,7 +515,7 @@ static int cpufreq_governor_userspace(struct cpufreq_policy *policy,
 		cpu_is_managed[cpu] = 0;
 		cpu_min_freq[cpu] = 0;
 		cpu_max_freq[cpu] = 0;
-		device_remove_file (policy->dev, &dev_attr_scaling_setspeed);
+		sysfs_remove_file (&policy->kobj, &freq_attr_scaling_setspeed.attr);
 		up(&userspace_sem);
 		module_put(THIS_MODULE);
 		break;

include/linux/cpufreq.h

@@ -18,7 +18,8 @@
 #include <linux/notifier.h>
 #include <linux/threads.h>
 #include <linux/device.h>
-
+#include <linux/kobject.h>
+#include <linux/sysfs.h>
 
 #define CPUFREQ_NAME_LEN 16
 
@@ -69,6 +70,8 @@ struct cpufreq_policy {
 	struct cpufreq_cpuinfo  cpuinfo;     /* see above */
 	struct device		* dev;
 	struct kobject		kobj;
+ 	struct semaphore	lock;   /* CPU ->setpolicy or ->target may
+					   only be called once a time */
 };
 
 #define CPUFREQ_ADJUST          (0)
@@ -131,18 +134,13 @@ struct cpufreq_governor {
 };
 
 /* pass a target to the cpufreq driver 
- * _l : (cpufreq_driver_sem is not held)
  */
 inline int cpufreq_driver_target(struct cpufreq_policy *policy,
 				 unsigned int target_freq,
 				 unsigned int relation);
 
-inline int cpufreq_driver_target_l(struct cpufreq_policy *policy,
-				   unsigned int target_freq,
-				   unsigned int relation);
-
 /* pass an event to the cpufreq governor */
-int cpufreq_governor_l(unsigned int cpu, unsigned int event);
+int cpufreq_governor(unsigned int cpu, unsigned int event);
 
 int cpufreq_register_governor(struct cpufreq_governor *governor);
 void cpufreq_unregister_governor(struct cpufreq_governor *governor);
@@ -154,6 +152,8 @@ void cpufreq_unregister_governor(struct cpufreq_governor *governor);
 #define CPUFREQ_RELATION_L 0  /* lowest frequency at or above target */
 #define CPUFREQ_RELATION_H 1  /* highest frequency below or at target */
 
+struct freq_attr;
+
 struct cpufreq_driver {
 	/* needed by all drivers */
 	int	(*verify)	(struct cpufreq_policy *policy);
@@ -164,16 +164,15 @@ struct cpufreq_driver {
 	int	(*target)	(struct cpufreq_policy *policy,
 				 unsigned int target_freq,
 				 unsigned int relation);
+	struct module           *owner;
 	/* optional, for the moment */
 	int	(*init)		(struct cpufreq_policy *policy);
 	int	(*exit)		(struct cpufreq_policy *policy);
+	struct freq_attr	**attr;
 };
 
 int cpufreq_register_driver(struct cpufreq_driver *driver_data);
 int cpufreq_unregister_driver(struct cpufreq_driver *driver_data);
-/* deprecated */
-#define cpufreq_register(x)   cpufreq_register_driver(x)
-#define cpufreq_unregister() cpufreq_unregister_driver(NULL)
 
 
 void cpufreq_notify_transition(struct cpufreq_freqs *freqs, unsigned int state);
@@ -194,6 +193,13 @@ static inline void cpufreq_verify_within_limits(struct cpufreq_policy *policy, u
 	return;
 }
 
+struct freq_attr {
+	struct attribute attr;
+	ssize_t (*show)(struct cpufreq_policy *, char *);
+	ssize_t (*store)(struct cpufreq_policy *, const char *, size_t count);
+};
+
+
 /*********************************************************************
  *                        CPUFREQ 2.6. INTERFACE                     *
  *********************************************************************/
@@ -289,16 +295,21 @@ int cpufreq_frequency_table_cpuinfo(struct cpufreq_policy *policy,
 int cpufreq_frequency_table_verify(struct cpufreq_policy *policy,
 				   struct cpufreq_frequency_table *table);
 
-int cpufreq_frequency_table_setpolicy(struct cpufreq_policy *policy,
-				      struct cpufreq_frequency_table *table,
-				      unsigned int *index);
-
 int cpufreq_frequency_table_target(struct cpufreq_policy *policy,
 				   struct cpufreq_frequency_table *table,
 				   unsigned int target_freq,
 				   unsigned int relation,
 				   unsigned int *index);
 
+/* the following are really really optional */
+extern struct freq_attr cpufreq_freq_attr_scaling_available_freqs;
+
+void cpufreq_frequency_table_get_attr(struct cpufreq_frequency_table *table, 
+				      unsigned int cpu);
+
+void cpufreq_frequency_table_put_attr(unsigned int cpu);
+
+
 #endif /* CONFIG_CPU_FREQ_TABLE */
 
 #endif /* _LINUX_CPUFREQ_H */

include/linux/pci_ids.h

@@ -1854,6 +1854,7 @@
 #define PCI_DEVICE_ID_INTEL_82801DB_7	0x24c7
 #define PCI_DEVICE_ID_INTEL_82801DB_9	0x24cb
 #define PCI_DEVICE_ID_INTEL_82801DB_11	PCI_DEVICE_ID_INTEL_82801DB_9
+#define PCI_DEVICE_ID_INTEL_82801DB_12  0x24cc
 #define PCI_DEVICE_ID_INTEL_82801DB_13	0x24cd
 #define PCI_DEVICE_ID_INTEL_82820_HB	0x2500
 #define PCI_DEVICE_ID_INTEL_82820_UP_HB	0x2501

kernel/cpufreq.c

@@ -43,12 +43,40 @@ static DECLARE_MUTEX            (cpufreq_driver_sem);
  */
 static struct notifier_block    *cpufreq_policy_notifier_list;
 static struct notifier_block    *cpufreq_transition_notifier_list;
-static DECLARE_MUTEX            (cpufreq_notifier_sem);
+static DECLARE_RWSEM		(cpufreq_notifier_rwsem);
 
 
 LIST_HEAD(cpufreq_governor_list);
+static DECLARE_MUTEX		(cpufreq_governor_sem);
 
-static int cpufreq_governor(unsigned int cpu, unsigned int event);
+static struct device_interface cpufreq_interface;
+
+static int cpufreq_cpu_get(unsigned int cpu) {
+	if (cpu >= NR_CPUS)
+		return 0;
+
+	if (!kset_get(&cpufreq_interface.kset))
+		return 0;
+
+	if (!try_module_get(cpufreq_driver->owner)) {
+		kset_put(&cpufreq_interface.kset);
+		return 0;
+	}
+
+	if (!kobject_get(&cpufreq_driver->policy[cpu].kobj)) {
+		module_put(cpufreq_driver->owner);
+		kset_put(&cpufreq_interface.kset);
+		return 0;
+	}
+
+	return 1;
+}
+
+static void cpufreq_cpu_put(unsigned int cpu) {
+	kobject_put(&cpufreq_driver->policy[cpu].kobj);
+	module_put(cpufreq_driver->owner);
+	kset_put(&cpufreq_interface.kset);
+}
 
 /*********************************************************************
  *                          SYSFS INTERFACE                          *
@@ -67,19 +95,19 @@ int cpufreq_parse_governor (char *str_governor, unsigned int *policy, struct cpu
 		return 0;
 	} else 	{
 		struct cpufreq_governor *t;
-		down(&cpufreq_driver_sem);
+		down(&cpufreq_governor_sem);
 		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;
 				*policy = CPUFREQ_POLICY_GOVERNOR;
-				up(&cpufreq_driver_sem);
+				up(&cpufreq_governor_sem);
 				return 0;
 			}
 		}
 	out:
-		up(&cpufreq_driver_sem);
+		up(&cpufreq_governor_sem);
 	}
 	return -EINVAL;
 }
@@ -120,14 +148,7 @@ static inline int to_cpu_nr (struct device *dev)
 static ssize_t show_##file_name 					\
 (struct cpufreq_policy * policy, char *buf)				\
 {									\
-	unsigned int value = 0;						\
-									\
-	down(&cpufreq_driver_sem);					\
-	if (cpufreq_driver)						\
-		value = policy->object;					\
-	up(&cpufreq_driver_sem);					\
-									\
-	return sprintf (buf, "%u\n", value);				\
+	return sprintf (buf, "%u\n", policy->object);			\
 }
 
 show_one(cpuinfo_min_freq, cpuinfo.min_freq);
@@ -143,12 +164,17 @@ static ssize_t store_##file_name					\
 (struct cpufreq_policy * policy, const char *buf, size_t count)		\
 {									\
 	unsigned int ret = -EINVAL;					\
+	struct cpufreq_policy new_policy;				\
 									\
-	ret = sscanf (buf, "%u", &policy->object);			\
+	ret = cpufreq_get_policy(&new_policy, policy->cpu);		\
+	if (ret)							\
+		return -EINVAL;						\
+									\
+	ret = sscanf (buf, "%u", &new_policy.object);			\
 	if (ret != 1)							\
 		return -EINVAL;						\
 									\
-	ret = cpufreq_set_policy(policy);				\
+	ret = cpufreq_set_policy(&new_policy);				\
 									\
 	return ret ? ret : count;					\
 }
@@ -161,26 +187,16 @@ store_one(scaling_max_freq,max);
  */
 static ssize_t show_scaling_governor (struct cpufreq_policy * policy, char *buf)
 {
-	unsigned int value = 0;
-	char value2[CPUFREQ_NAME_LEN];
-
-	down(&cpufreq_driver_sem);
-	if (cpufreq_driver)
-		value = policy->policy;
-	if (value == CPUFREQ_POLICY_GOVERNOR)
-		strncpy(value2, policy->governor->name, CPUFREQ_NAME_LEN);
-	up(&cpufreq_driver_sem);
-
-	switch (value) {
+	switch (policy->policy) {
 	case CPUFREQ_POLICY_POWERSAVE:
 		return sprintf(buf, "powersave\n");
 	case CPUFREQ_POLICY_PERFORMANCE:
 		return sprintf(buf, "performance\n");
 	case CPUFREQ_POLICY_GOVERNOR:
-		return sprintf(buf, "%s\n", value2);
+		return snprintf(buf, CPUFREQ_NAME_LEN, "%s\n", policy->governor->name);
+	default:
+		return -EINVAL;
 	}
-
-	return -EINVAL;
 }
 
 
@@ -192,25 +208,55 @@ static ssize_t store_scaling_governor (struct cpufreq_policy * policy,
 {
 	unsigned int ret = -EINVAL;
 	char	str_governor[16];
+	struct cpufreq_policy new_policy;
+
+	ret = cpufreq_get_policy(&new_policy, policy->cpu);
+	if (ret)
+		return ret;
 
 	ret = sscanf (buf, "%15s", str_governor);
 	if (ret != 1)
 		return -EINVAL;
 
-	if (cpufreq_parse_governor(str_governor, &policy->policy, &policy->governor))
+	if (cpufreq_parse_governor(str_governor, &new_policy.policy, &new_policy.governor))
 		return -EINVAL;
 
-	ret = cpufreq_set_policy(policy);
+	ret = cpufreq_set_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 snprintf(buf, CPUFREQ_NAME_LEN, "%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;
+
+	i += sprintf(buf, "performance powersave");
+
+	if (!cpufreq_driver->target)
+		goto out;
+
+	list_for_each_entry(t, &cpufreq_governor_list, governor_list) {
+		if (i >= (ssize_t) ((PAGE_SIZE / sizeof(char)) - (CPUFREQ_NAME_LEN + 2)))
+			goto out;
+		i += snprintf(&buf[i], CPUFREQ_NAME_LEN, " %s", t->name);
+	}
+ out:
+	i += sprintf(&buf[i], "\n");
+	return i;
+}
 
-struct freq_attr {
-	struct attribute attr;
-	ssize_t (*show)(struct cpufreq_policy *, char *);
-	ssize_t (*store)(struct cpufreq_policy *, const char *, size_t count);
-};
 
 #define define_one_ro(_name) \
 struct freq_attr _name = { \
@@ -227,6 +273,8 @@ struct freq_attr _name = { \
 
 define_one_ro(cpuinfo_min_freq);
 define_one_ro(cpuinfo_max_freq);
+define_one_ro(scaling_available_governors);
+define_one_ro(scaling_driver);
 define_one_rw(scaling_min_freq);
 define_one_rw(scaling_max_freq);
 define_one_rw(scaling_governor);
@@ -237,10 +285,11 @@ static struct attribute * default_attrs[] = {
 	&scaling_min_freq.attr,
 	&scaling_max_freq.attr,
 	&scaling_governor.attr,
+	&scaling_driver.attr,
+	&scaling_available_governors.attr,
 	NULL
 };
 
-
 #define to_policy(k) container_of(k,struct cpufreq_policy,kobj)
 #define to_attr(a) container_of(a,struct freq_attr,attr)
 
@@ -248,7 +297,12 @@ 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);
-	return fattr->show ? fattr->show(policy,buf) : 0;
+	ssize_t ret;
+	if (!cpufreq_cpu_get(policy->cpu))
+		return -EINVAL;
+	ret = fattr->show ? fattr->show(policy,buf) : 0;
+	cpufreq_cpu_put(policy->cpu);
+	return ret;
 }
 
 static ssize_t store(struct kobject * kobj, struct attribute * attr, 
@@ -256,7 +310,12 @@ static ssize_t store(struct kobject * kobj, struct attribute * attr,
 {
 	struct cpufreq_policy * policy = to_policy(kobj);
 	struct freq_attr * fattr = to_attr(attr);
-	return fattr->store ? fattr->store(policy,buf,count) : 0;
+	ssize_t ret;
+	if (!cpufreq_cpu_get(policy->cpu))
+		return -EINVAL;
+	ret = fattr->store ? fattr->store(policy,buf,count) : 0;
+	cpufreq_cpu_put(policy->cpu);
+	return ret;
 }
 
 static struct sysfs_ops sysfs_ops = {
@@ -270,56 +329,6 @@ static struct kobj_type ktype_cpufreq = {
 };
 
 
-/**
- * show_scaling_governor - show the current policy for the specified CPU
- */
-static ssize_t show_scaling_driver (struct device *dev, char *buf)
-{
-	char value[CPUFREQ_NAME_LEN];
-
-	if (!dev)
-		return 0;
-
-	down(&cpufreq_driver_sem);
-	if (cpufreq_driver)
-		strncpy(value, cpufreq_driver->name, CPUFREQ_NAME_LEN);
-	up(&cpufreq_driver_sem);
-
-	return sprintf(buf, "%s\n", value);
-}
-
-/**
- * show_available_govs - show the available CPUfreq governors
- */
-static ssize_t show_available_govs(struct device *dev, char *buf)
-{
-	ssize_t i = 0;
-	struct cpufreq_governor *t;
-
-	if (!dev)
-		return 0;
-
-	i += sprintf(buf, "performance powersave");
-
-	down(&cpufreq_driver_sem);
-	if (!cpufreq_driver || !cpufreq_driver->target)
-		goto out;
-
-	list_for_each_entry(t, &cpufreq_governor_list, governor_list) {
-		if (i >= (ssize_t) ((PAGE_SIZE / sizeof(char)) - (CPUFREQ_NAME_LEN + 2)))
-			goto out;
-		i += snprintf(&buf[i], CPUFREQ_NAME_LEN, " %s", t->name);
-	}
- out:
-	up(&cpufreq_driver_sem);
-	i += sprintf(&buf[i], "\n");
-	return i;
-}
-
-
-static DEVICE_ATTR(scaling_driver, S_IRUGO, show_scaling_driver, NULL);
-static DEVICE_ATTR(available_scaling_governors, S_IRUGO, show_available_govs, NULL);
-
 /**
  * cpufreq_add_dev - add a CPU device
  *
@@ -329,57 +338,62 @@ static int cpufreq_add_dev (struct device * dev)
 {
 	unsigned int cpu = to_cpu_nr(dev);
 	int ret = 0;
-	struct cpufreq_policy policy;
+	struct cpufreq_policy new_policy;
+	struct cpufreq_policy *policy;
+	struct freq_attr **drv_attr;
 
-	down(&cpufreq_driver_sem);
-	if (!cpufreq_driver) {
-		up(&cpufreq_driver_sem);
+	if (!kset_get(&cpufreq_interface.kset))
+		return -EINVAL;
+
+	if (!try_module_get(cpufreq_driver->owner)) {
+		kset_put(&cpufreq_interface.kset);
 		return -EINVAL;
 	}
 
 	/* call driver. From then on the cpufreq must be able
 	 * to accept all calls to ->verify and ->setpolicy for this CPU
 	 */
-	cpufreq_driver->policy[cpu].cpu = cpu;
+	policy = &cpufreq_driver->policy[cpu];
+	policy->cpu = cpu;
 	if (cpufreq_driver->init) {
-		ret = cpufreq_driver->init(&cpufreq_driver->policy[cpu]);
-		if (ret) {
-			up(&cpufreq_driver_sem);
-			return -ENODEV;
-		}
+		ret = cpufreq_driver->init(policy);
+		if (ret)
+			goto out;
 	}
 
 	/* set default policy on this CPU */
-	memcpy(&policy, 
-	       &cpufreq_driver->policy[cpu], 
+	down(&cpufreq_driver_sem);
+	memcpy(&new_policy, 
+	       policy, 
 	       sizeof(struct cpufreq_policy));
-
-	/* 2.4-API init for this CPU */
-#ifdef CONFIG_CPU_FREQ_24_API
-	cpu_min_freq[cpu] = cpufreq_driver->policy[cpu].cpuinfo.min_freq;
-	cpu_max_freq[cpu] = cpufreq_driver->policy[cpu].cpuinfo.max_freq;
-	cpu_cur_freq[cpu] = cpufreq_driver->cpu_cur_freq[cpu];
-#endif
-
-	if (cpufreq_driver->target)
-		cpufreq_governor(cpu, CPUFREQ_GOV_START);
-
 	up(&cpufreq_driver_sem);
-	ret = cpufreq_set_policy(&policy);
-	if (ret)
-		return -EINVAL;
-	down(&cpufreq_driver_sem);
 
+	init_MUTEX(&policy->lock);
 	/* prepare interface data */
-	policy.kobj.parent = &dev->kobj;
-	policy.kobj.ktype = &ktype_cpufreq;
-	policy.dev = dev;
-	strncpy(policy.kobj.name, 
+	policy->kobj.parent = &dev->kobj;
+	policy->kobj.ktype = &ktype_cpufreq;
+	policy->dev = dev;
+	strncpy(policy->kobj.name, 
 		cpufreq_interface.name, KOBJ_NAME_LEN);
 
-	ret = kobject_register(&policy.kobj);
+	ret = kobject_register(&policy->kobj);
+	if (ret)
+		goto out;
+
+	drv_attr = cpufreq_driver->attr;
+	while ((drv_attr) && (*drv_attr)) {
+		sysfs_create_file(&policy->kobj, &((*drv_attr)->attr));
+		drv_attr++;
+	}
 
-	up(&cpufreq_driver_sem);
+	/* set default policy */
+	ret = cpufreq_set_policy(&new_policy);
+	if (ret)
+		kobject_unregister(&policy->kobj);
+
+ out:
+	module_put(cpufreq_driver->owner);
+	kset_put(&cpufreq_interface.kset);
 	return ret;
 }
 
@@ -387,21 +401,39 @@ static int cpufreq_add_dev (struct device * dev)
 /**
  * cpufreq_remove_dev - remove a CPU device
  *
- * Removes the cpufreq interface for a CPU device. Is called with
- * cpufreq_driver_sem locked.
+ * Removes the cpufreq interface for a CPU device.
  */
 static int cpufreq_remove_dev (struct device * dev)
 {
 	unsigned int cpu = to_cpu_nr(dev);
 
-	if (cpufreq_driver->target)
-		cpufreq_governor(cpu, CPUFREQ_GOV_STOP);
+	if (!kset_get(&cpufreq_interface.kset))
+		return -EINVAL;
+
+	if (!kobject_get(&cpufreq_driver->policy[cpu].kobj)) {
+		kset_put(&cpufreq_interface.kset);
+		return -EINVAL;
+	}
 
+	down(&cpufreq_driver_sem);
+	if ((cpufreq_driver->target) && 
+	    (cpufreq_driver->policy[cpu].policy == CPUFREQ_POLICY_GOVERNOR)) {
+		cpufreq_driver->policy[cpu].governor->governor(&cpufreq_driver->policy[cpu], CPUFREQ_GOV_STOP);
+		module_put(cpufreq_driver->policy[cpu].governor->owner);
+	}
+
+	/* we may call driver->exit here without checking for try_module_exit
+	 * as it's either the driver which wants to unload or we have a CPU
+	 * removal AND driver removal at the same time...
+	 */
 	if (cpufreq_driver->exit)
 		cpufreq_driver->exit(&cpufreq_driver->policy[cpu]);
 
 	kobject_unregister(&cpufreq_driver->policy[cpu].kobj);
 
+	up(&cpufreq_driver_sem);
+	kobject_put(&cpufreq_driver->policy[cpu].kobj);
+	kset_put(&cpufreq_interface.kset);
 	return 0;
 }
 
@@ -427,7 +459,7 @@ int cpufreq_register_notifier(struct notifier_block *nb, unsigned int list)
 {
 	int ret;
 
-	down(&cpufreq_notifier_sem);
+	down_write(&cpufreq_notifier_rwsem);
 	switch (list) {
 	case CPUFREQ_TRANSITION_NOTIFIER:
 		ret = notifier_chain_register(&cpufreq_transition_notifier_list, nb);
@@ -438,7 +470,7 @@ int cpufreq_register_notifier(struct notifier_block *nb, unsigned int list)
 	default:
 		ret = -EINVAL;
 	}
-	up(&cpufreq_notifier_sem);
+	up_write(&cpufreq_notifier_rwsem);
 
 	return ret;
 }
@@ -459,7 +491,7 @@ int cpufreq_unregister_notifier(struct notifier_block *nb, unsigned int list)
 {
 	int ret;
 
-	down(&cpufreq_notifier_sem);
+	down_write(&cpufreq_notifier_rwsem);
 	switch (list) {
 	case CPUFREQ_TRANSITION_NOTIFIER:
 		ret = notifier_chain_unregister(&cpufreq_transition_notifier_list, nb);
@@ -470,7 +502,7 @@ int cpufreq_unregister_notifier(struct notifier_block *nb, unsigned int list)
 	default:
 		ret = -EINVAL;
 	}
-	up(&cpufreq_notifier_sem);
+	up_write(&cpufreq_notifier_rwsem);
 
 	return ret;
 }
@@ -481,71 +513,72 @@ EXPORT_SYMBOL(cpufreq_unregister_notifier);
  *                              GOVERNORS                            *
  *********************************************************************/
 
-inline int cpufreq_driver_target_l(struct cpufreq_policy *policy,
-				   unsigned int target_freq,
-				   unsigned int relation)
-{
-	unsigned int ret;
-	down(&cpufreq_driver_sem);
-	if (!cpufreq_driver)
-		ret = -EINVAL;
-	else
-		ret = cpufreq_driver->target(policy, target_freq, relation);
-	up(&cpufreq_driver_sem);
-	return ret;
-}
-EXPORT_SYMBOL_GPL(cpufreq_driver_target_l);
-
-
 inline int cpufreq_driver_target(struct cpufreq_policy *policy,
 				 unsigned int target_freq,
 				 unsigned int relation)
 {
-	return cpufreq_driver->target(policy, target_freq, relation);
+	unsigned int ret;
+	unsigned int cpu = policy->cpu;
+
+	if (!cpufreq_cpu_get(cpu))
+		return -EINVAL;
+
+	down(&cpufreq_driver->policy[cpu].lock);
+
+	ret = cpufreq_driver->target(policy, target_freq, relation);
+
+	up(&cpufreq_driver->policy[cpu].lock);
+
+	cpufreq_cpu_put(cpu);
+
+	return ret;
 }
 EXPORT_SYMBOL_GPL(cpufreq_driver_target);
 
 
-static int cpufreq_governor(unsigned int cpu, unsigned int event)
+int cpufreq_governor(unsigned int cpu, unsigned int event)
 {
 	int ret = 0;
 	struct cpufreq_policy *policy = &cpufreq_driver->policy[cpu];
 
+	if (!cpufreq_cpu_get(cpu))
+		return -EINVAL;
+
 	switch (policy->policy) {
 	case CPUFREQ_POLICY_POWERSAVE: 
-		if ((event == CPUFREQ_GOV_LIMITS) || (event == CPUFREQ_GOV_START))
+		if ((event == CPUFREQ_GOV_LIMITS) || (event == CPUFREQ_GOV_START)) {
+			down(&cpufreq_driver->policy[cpu].lock);
 			ret = cpufreq_driver->target(policy, policy->min, CPUFREQ_RELATION_L);
+			up(&cpufreq_driver->policy[cpu].lock);
+		}
 		break;
 	case CPUFREQ_POLICY_PERFORMANCE:
-		if ((event == CPUFREQ_GOV_LIMITS) || (event == CPUFREQ_GOV_START))
+		if ((event == CPUFREQ_GOV_LIMITS) || (event == CPUFREQ_GOV_START)) {
+			down(&cpufreq_driver->policy[cpu].lock);
 			ret = cpufreq_driver->target(policy, policy->max, CPUFREQ_RELATION_H);
+			up(&cpufreq_driver->policy[cpu].lock);
+		}
 		break;
 	case CPUFREQ_POLICY_GOVERNOR:
 		ret = -EINVAL;
-		if (event == CPUFREQ_GOV_START)
-			if (!try_module_get(cpufreq_driver->policy[cpu].governor->owner))
-				break;
+		if (!try_module_get(cpufreq_driver->policy[cpu].governor->owner))
+			break;
 		ret = cpufreq_driver->policy[cpu].governor->governor(policy, event);
-		if ((event == CPUFREQ_GOV_STOP) ||
-			(ret && (event == CPUFREQ_GOV_START)))
+		/* we keep one module reference alive for each CPU governed by this CPU */
+		if ((event != CPUFREQ_GOV_START) || ret)
+			module_put(cpufreq_driver->policy[cpu].governor->owner);
+		if ((event == CPUFREQ_GOV_STOP) && !ret)
 			module_put(cpufreq_driver->policy[cpu].governor->owner);
 		break;
 	default:
 		ret = -EINVAL;
 	}
-	return ret;
-}
 
+	cpufreq_cpu_put(cpu);
 
-int cpufreq_governor_l(unsigned int cpu, unsigned int event)
-{
-	int ret = 0;
-	down(&cpufreq_driver_sem);
-	ret = cpufreq_governor(cpu, event);
-	up(&cpufreq_driver_sem);
 	return ret;
 }
-EXPORT_SYMBOL_GPL(cpufreq_governor_l);
+EXPORT_SYMBOL_GPL(cpufreq_governor);
 
 
 int cpufreq_register_governor(struct cpufreq_governor *governor)
@@ -560,16 +593,17 @@ int cpufreq_register_governor(struct cpufreq_governor *governor)
 	if (!strnicmp(governor->name,"performance",CPUFREQ_NAME_LEN))
 		return -EBUSY;
 
-	down(&cpufreq_driver_sem);
+	down(&cpufreq_governor_sem);
 	
 	list_for_each_entry(t, &cpufreq_governor_list, governor_list) {
 		if (!strnicmp(governor->name,t->name,CPUFREQ_NAME_LEN)) {
-			up(&cpufreq_driver_sem);
+			up(&cpufreq_governor_sem);
 			return -EBUSY;
 		}
 	}
 	list_add(&governor->governor_list, &cpufreq_governor_list);
- 	up(&cpufreq_driver_sem);
+
+ 	up(&cpufreq_governor_sem);
 
 	return 0;
 }
@@ -583,7 +617,8 @@ void cpufreq_unregister_governor(struct cpufreq_governor *governor)
 	if (!governor)
 		return;
 
-	down(&cpufreq_driver_sem);
+	down(&cpufreq_governor_sem);
+
 	/* 
 	 * Unless the user uses rmmod -f, we can be safe. But we never
 	 * know, so check whether if it's currently used. If so,
@@ -591,17 +626,21 @@ void cpufreq_unregister_governor(struct cpufreq_governor *governor)
 	 */
 	for (i=0; i<NR_CPUS; i++)
 	{
-		if (cpufreq_driver && 
-		    (cpufreq_driver->policy[i].policy == CPUFREQ_POLICY_GOVERNOR) && 
+		if (!cpufreq_cpu_get(i))
+			continue;
+		if ((cpufreq_driver->policy[i].policy == CPUFREQ_POLICY_GOVERNOR) && 
 		    (cpufreq_driver->policy[i].governor == governor)) {
 			cpufreq_governor(i, CPUFREQ_GOV_STOP);
 			cpufreq_driver->policy[i].policy = CPUFREQ_POLICY_PERFORMANCE;
 			cpufreq_governor(i, CPUFREQ_GOV_START);
+			cpufreq_governor(i, CPUFREQ_GOV_LIMITS);
 		}
+		cpufreq_cpu_put(i);
 	}
+
 	/* now we can safely remove it from the list */
 	list_del(&governor->governor_list);
-	up(&cpufreq_driver_sem);
+	up(&cpufreq_governor_sem);
 	return;
 }
 EXPORT_SYMBOL_GPL(cpufreq_unregister_governor);
@@ -620,19 +659,17 @@ EXPORT_SYMBOL_GPL(cpufreq_unregister_governor);
  */
 int cpufreq_get_policy(struct cpufreq_policy *policy, unsigned int cpu)
 {
-	down(&cpufreq_driver_sem);
-	if (!cpufreq_driver  || !policy || 
-	    (cpu >= NR_CPUS) || (!cpu_online(cpu))) {
-		up(&cpufreq_driver_sem);
+	if (!policy || !cpufreq_cpu_get(cpu))
 		return -EINVAL;
-	}
 
+	down(&cpufreq_driver_sem);
 	memcpy(policy, 
 	       &cpufreq_driver->policy[cpu], 
 	       sizeof(struct cpufreq_policy));
-	
 	up(&cpufreq_driver_sem);
 
+	cpufreq_cpu_put(cpu);
+
 	return 0;
 }
 EXPORT_SYMBOL(cpufreq_get_policy);
@@ -646,27 +683,23 @@ EXPORT_SYMBOL(cpufreq_get_policy);
  */
 int cpufreq_set_policy(struct cpufreq_policy *policy)
 {
-	int ret;
+	int ret = 0;
 
-	down(&cpufreq_driver_sem);
-	if (!cpufreq_driver || !policy ||
-	    (policy->cpu >= NR_CPUS) || (!cpu_online(policy->cpu))) {
-		up(&cpufreq_driver_sem);
+	if (!policy || !cpufreq_cpu_get(policy->cpu))
 		return -EINVAL;
-	}
 
+	down(&cpufreq_driver_sem);
 	memcpy(&policy->cpuinfo, 
 	       &cpufreq_driver->policy[policy->cpu].cpuinfo, 
 	       sizeof(struct cpufreq_cpuinfo));
+	up(&cpufreq_driver_sem);
 
 	/* verify the cpu speed can be set within this limit */
 	ret = cpufreq_driver->verify(policy);
-	if (ret) {
-		up(&cpufreq_driver_sem);
-		return ret;
-	}
+	if (ret)
+		goto error_out;
 
-	down(&cpufreq_notifier_sem);
+	down_read(&cpufreq_notifier_rwsem);
 
 	/* adjust if necessary - all reasons */
 	notifier_call_chain(&cpufreq_policy_notifier_list, CPUFREQ_ADJUST,
@@ -680,17 +713,18 @@ int cpufreq_set_policy(struct cpufreq_policy *policy)
 	   which might be different to the first one */
 	ret = cpufreq_driver->verify(policy);
 	if (ret) {
-		up(&cpufreq_notifier_sem);
-		up(&cpufreq_driver_sem);
-		return ret;
+		up_read(&cpufreq_notifier_rwsem);
+		goto error_out;
 	}
 
 	/* notification of the new policy */
 	notifier_call_chain(&cpufreq_policy_notifier_list, CPUFREQ_NOTIFY,
 			    policy);
 
-	up(&cpufreq_notifier_sem);
+	up_read(&cpufreq_notifier_rwsem);
 
+	/* from here on we limit it to one limit and/or governor change running at the moment */
+	down(&cpufreq_driver_sem);
 	cpufreq_driver->policy[policy->cpu].min    = policy->min;
 	cpufreq_driver->policy[policy->cpu].max    = policy->max;
 
@@ -718,9 +752,11 @@ int cpufreq_set_policy(struct cpufreq_policy *policy)
 			cpufreq_governor(policy->cpu, CPUFREQ_GOV_LIMITS);
 		}
 	}
-	
 	up(&cpufreq_driver_sem);
 
+ error_out:	
+	cpufreq_cpu_put(policy->cpu);
+
 	return ret;
 }
 EXPORT_SYMBOL(cpufreq_set_policy);
@@ -766,7 +802,7 @@ static inline void adjust_jiffies(unsigned long val, struct cpufreq_freqs *ci)
  */
 void cpufreq_notify_transition(struct cpufreq_freqs *freqs, unsigned int state)
 {
-	down(&cpufreq_notifier_sem);
+	down_read(&cpufreq_notifier_rwsem);
 	switch (state) {
 	case CPUFREQ_PRECHANGE:
 		notifier_call_chain(&cpufreq_transition_notifier_list, CPUFREQ_PRECHANGE, freqs);
@@ -778,7 +814,7 @@ void cpufreq_notify_transition(struct cpufreq_freqs *freqs, unsigned int state)
 		cpufreq_driver->policy[freqs->cpu].cur = freqs->new;
 		break;
 	}
-	up(&cpufreq_notifier_sem);
+	up_read(&cpufreq_notifier_rwsem);
 }
 EXPORT_SYMBOL_GPL(cpufreq_notify_transition);
 
@@ -800,38 +836,33 @@ EXPORT_SYMBOL_GPL(cpufreq_notify_transition);
  */
 int cpufreq_register_driver(struct cpufreq_driver *driver_data)
 {
-	int ret = 0;
-
-	if (cpufreq_driver)
-		return -EBUSY;
-	
-	if (!driver_data || !driver_data->verify || 
+	if (!driver_data || !driver_data->verify || !driver_data->init ||
 	    ((!driver_data->setpolicy) && (!driver_data->target)))
 		return -EINVAL;
 
-	down(&cpufreq_driver_sem);
 
+	if (kset_get(&cpufreq_interface.kset)) {
+		kset_put(&cpufreq_interface.kset);
+		return -EBUSY;
+	}
+
+	down(&cpufreq_driver_sem);
+	if (cpufreq_driver) {
+		up(&cpufreq_driver_sem);		
+		return -EBUSY;
+	}
 	cpufreq_driver = driver_data;
+	up(&cpufreq_driver_sem);
 
+	cpufreq_driver->policy = kmalloc(NR_CPUS * sizeof(struct cpufreq_policy), GFP_KERNEL);
 	if (!cpufreq_driver->policy) {
-		/* then we need per-CPU init */
-		if (!cpufreq_driver->init) {
-			up(&cpufreq_driver_sem);
-			return -EINVAL;
-		}
-		cpufreq_driver->policy = kmalloc(NR_CPUS * sizeof(struct cpufreq_policy), GFP_KERNEL);
-		if (!cpufreq_driver->policy) {
-			up(&cpufreq_driver_sem);
-			return -ENOMEM;
-		}
-		memset(cpufreq_driver->policy, 0, NR_CPUS * sizeof(struct cpufreq_policy));
+		cpufreq_driver = NULL;
+		return -ENOMEM;
 	}
-	
-	up(&cpufreq_driver_sem);
 
-	ret = interface_register(&cpufreq_interface);
+	memset(cpufreq_driver->policy, 0, NR_CPUS * sizeof(struct cpufreq_policy));
 
-	return ret;
+	return interface_register(&cpufreq_interface);
 }
 EXPORT_SYMBOL_GPL(cpufreq_register_driver);
 
@@ -846,20 +877,20 @@ EXPORT_SYMBOL_GPL(cpufreq_register_driver);
  */
 int cpufreq_unregister_driver(struct cpufreq_driver *driver)
 {
-	down(&cpufreq_driver_sem);
+	if (!kset_get(&cpufreq_interface.kset))
+		return 0;
 
-	if (!cpufreq_driver || 
-	    ((driver != cpufreq_driver) && (driver != NULL))) { /* compat */
-		up(&cpufreq_driver_sem);
+	if (!cpufreq_driver || (driver != cpufreq_driver)) {
+		kset_put(&cpufreq_interface.kset);
 		return -EINVAL;
 	}
 
+	kset_put(&cpufreq_interface.kset);
 	interface_unregister(&cpufreq_interface);
 
-	if (driver)
-		kfree(cpufreq_driver->policy);
+	down(&cpufreq_driver_sem);
+	kfree(cpufreq_driver->policy);
 	cpufreq_driver = NULL;
-
 	up(&cpufreq_driver_sem);
 
 	return 0;
@@ -883,22 +914,28 @@ int cpufreq_restore(void)
 	if (in_interrupt())
 		panic("cpufreq_restore() called from interrupt context!");
 
+	if (!kset_get(&cpufreq_interface.kset))
+		return 0;
+
+	if (!try_module_get(cpufreq_driver->owner))
+		goto error_out;
+
 	for (i=0;i<NR_CPUS;i++) {
-		if (!cpu_online(i))
+		if (!cpu_online(i) || !cpufreq_cpu_get(i))
 			continue;
 
 		down(&cpufreq_driver_sem);
-		if (!cpufreq_driver) {
-			up(&cpufreq_driver_sem);
-			return 0;
-		}
-
 		memcpy(&policy, &cpufreq_driver->policy[i], sizeof(struct cpufreq_policy));
 		up(&cpufreq_driver_sem);
-
 		ret += cpufreq_set_policy(&policy);
+
+		cpufreq_cpu_put(i);
 	}
 
+	module_put(cpufreq_driver->owner);
+ error_out:
+	kset_put(&cpufreq_interface.kset);
+
 	return ret;
 }
 EXPORT_SYMBOL_GPL(cpufreq_restore);