Merge tag 'pull_req_20121120' of git://git.kernel.org/pub/scm/linux/kernel/git/mzx/devfreq into pm-devfreq

Devfreq pull request for Rafael from MyungJoo
Created on 2012.11.20 based on Linux 3.7-rc5

* tag 'pull_req_20121120' of git://git.kernel.org/pub/scm/linux/kernel/git/mzx/devfreq:
  PM / devfreq: exynos4_bus.c: Fixed an alignment of the func call args.
  PM / devfreq: Add sysfs node to expose available governors
  PM / devfreq: allow sysfs governor node to switch governor
  PM / devfreq: governors: add GPL module license and allow module build
  PM / devfreq: map devfreq drivers to governor using name
  PM / devfreq: register governors with devfreq framework
  PM / devfreq: provide hooks for governors to be registered
  PM / devfreq: export update_devfreq
  PM / devfreq: Add sysfs node for representing frequency transition information.
  PM / devfreq: Add sysfs node to expose available frequencies
  PM / devfreq: documentation cleanups for devfreq header
  PM / devfreq: Use devm_* functions in exynos4_bus.c

Documentation/ABI/testing/sysfs-class-devfreq

@@ -11,7 +11,7 @@ What:		/sys/class/devfreq/.../governor
 Date:		September 2011
 Contact:	MyungJoo Ham <myungjoo.ham@samsung.com>
 Description:
-		The /sys/class/devfreq/.../governor shows the name of the
+		The /sys/class/devfreq/.../governor show or set the name of the
 		governor used by the corresponding devfreq object.
 
 What:		/sys/class/devfreq/.../cur_freq
@@ -44,6 +44,17 @@ Description:
 		(/sys/class/devfreq/.../central_polling is 0), this value
 		may be useless.
 
+What:		/sys/class/devfreq/.../trans_stat
+Date:		October 2012
+Contact:	MyungJoo Ham <myungjoo.ham@samsung.com>
+Descrtiption:
+		This ABI shows the statistics of devfreq behavior on a
+		specific device. It shows the time spent in each state and
+		the number of transitions between states.
+		In order to activate this ABI, the devfreq target device
+		driver should provide the list of available frequencies
+		with its profile.
+
 What:		/sys/class/devfreq/.../userspace/set_freq
 Date:		September 2011
 Contact:	MyungJoo Ham <myungjoo.ham@samsung.com>
@@ -51,3 +62,19 @@ Description:
 		The /sys/class/devfreq/.../userspace/set_freq shows and
 		sets the requested frequency for the devfreq object if
 		userspace governor is in effect.
+
+What:		/sys/class/devfreq/.../available_frequencies
+Date:		October 2012
+Contact:	Nishanth Menon <nm@ti.com>
+Description:
+		The /sys/class/devfreq/.../available_frequencies shows
+		the available frequencies of the corresponding devfreq object.
+		This is a snapshot of available frequencies and not limited
+		by the min/max frequency restrictions.
+
+What:		/sys/class/devfreq/.../available_governors
+Date:		October 2012
+Contact:	Nishanth Menon <nm@ti.com>
+Description:
+		The /sys/class/devfreq/.../available_governors shows
+		currently available governors in the system.

drivers/devfreq/Kconfig

@@ -30,7 +30,7 @@ if PM_DEVFREQ
 comment "DEVFREQ Governors"
 
 config DEVFREQ_GOV_SIMPLE_ONDEMAND
-	bool "Simple Ondemand"
+	tristate "Simple Ondemand"
 	help
 	  Chooses frequency based on the recent load on the device. Works
 	  similar as ONDEMAND governor of CPUFREQ does. A device with
@@ -39,7 +39,7 @@ config DEVFREQ_GOV_SIMPLE_ONDEMAND
 	  values to the governor with data field at devfreq_add_device().
 
 config DEVFREQ_GOV_PERFORMANCE
-	bool "Performance"
+	tristate "Performance"
 	help
 	  Sets the frequency at the maximum available frequency.
 	  This governor always returns UINT_MAX as frequency so that
@@ -47,7 +47,7 @@ config DEVFREQ_GOV_PERFORMANCE
 	  at any time.
 
 config DEVFREQ_GOV_POWERSAVE
-	bool "Powersave"
+	tristate "Powersave"
 	help
 	  Sets the frequency at the minimum available frequency.
 	  This governor always returns 0 as frequency so that
@@ -55,7 +55,7 @@ config DEVFREQ_GOV_POWERSAVE
 	  at any time.
 
 config DEVFREQ_GOV_USERSPACE
-	bool "Userspace"
+	tristate "Userspace"
 	help
 	  Sets the frequency at the user specified one.
 	  This governor returns the user configured frequency if there

drivers/devfreq/devfreq.c

@@ -36,6 +36,8 @@ static struct class *devfreq_class;
  */
 static struct workqueue_struct *devfreq_wq;
 
+/* The list of all device-devfreq governors */
+static LIST_HEAD(devfreq_governor_list);
 /* The list of all device-devfreq */
 static LIST_HEAD(devfreq_list);
 static DEFINE_MUTEX(devfreq_list_lock);
@@ -66,6 +68,77 @@ static struct devfreq *find_device_devfreq(struct device *dev)
 	return ERR_PTR(-ENODEV);
 }
 
+/**
+ * devfreq_get_freq_level() - Lookup freq_table for the frequency
+ * @devfreq:	the devfreq instance
+ * @freq:	the target frequency
+ */
+static int devfreq_get_freq_level(struct devfreq *devfreq, unsigned long freq)
+{
+	int lev;
+
+	for (lev = 0; lev < devfreq->profile->max_state; lev++)
+		if (freq == devfreq->profile->freq_table[lev])
+			return lev;
+
+	return -EINVAL;
+}
+
+/**
+ * devfreq_update_status() - Update statistics of devfreq behavior
+ * @devfreq:	the devfreq instance
+ * @freq:	the update target frequency
+ */
+static int devfreq_update_status(struct devfreq *devfreq, unsigned long freq)
+{
+	int lev, prev_lev;
+	unsigned long cur_time;
+
+	lev = devfreq_get_freq_level(devfreq, freq);
+	if (lev < 0)
+		return lev;
+
+	cur_time = jiffies;
+	devfreq->time_in_state[lev] +=
+			 cur_time - devfreq->last_stat_updated;
+	if (freq != devfreq->previous_freq) {
+		prev_lev = devfreq_get_freq_level(devfreq,
+						devfreq->previous_freq);
+		devfreq->trans_table[(prev_lev *
+				devfreq->profile->max_state) + lev]++;
+		devfreq->total_trans++;
+	}
+	devfreq->last_stat_updated = cur_time;
+
+	return 0;
+}
+
+/**
+ * find_devfreq_governor() - find devfreq governor from name
+ * @name:	name of the governor
+ *
+ * Search the list of devfreq governors and return the matched
+ * governor's pointer. devfreq_list_lock should be held by the caller.
+ */
+static struct devfreq_governor *find_devfreq_governor(const char *name)
+{
+	struct devfreq_governor *tmp_governor;
+
+	if (unlikely(IS_ERR_OR_NULL(name))) {
+		pr_err("DEVFREQ: %s: Invalid parameters\n", __func__);
+		return ERR_PTR(-EINVAL);
+	}
+	WARN(!mutex_is_locked(&devfreq_list_lock),
+	     "devfreq_list_lock must be locked.");
+
+	list_for_each_entry(tmp_governor, &devfreq_governor_list, node) {
+		if (!strncmp(tmp_governor->name, name, DEVFREQ_NAME_LEN))
+			return tmp_governor;
+	}
+
+	return ERR_PTR(-ENODEV);
+}
+
 /* Load monitoring helper functions for governors use */
 
 /**
@@ -86,6 +159,9 @@ int update_devfreq(struct devfreq *devfreq)
 		return -EINVAL;
 	}
 
+	if (!devfreq->governor)
+		return -EINVAL;
+
 	/* Reevaluate the proper frequency */
 	err = devfreq->governor->get_target_freq(devfreq, &freq);
 	if (err)
@@ -112,9 +188,15 @@ int update_devfreq(struct devfreq *devfreq)
 	if (err)
 		return err;
 
+	if (devfreq->profile->freq_table)
+		if (devfreq_update_status(devfreq, freq))
+			dev_err(&devfreq->dev,
+				"Couldn't update frequency transition information.\n");
+
 	devfreq->previous_freq = freq;
 	return err;
 }
+EXPORT_SYMBOL(update_devfreq);
 
 /**
  * devfreq_monitor() - Periodically poll devfreq objects.
@@ -300,7 +382,9 @@ static void _remove_devfreq(struct devfreq *devfreq, bool skip)
 	list_del(&devfreq->node);
 	mutex_unlock(&devfreq_list_lock);
 
-	devfreq->governor->event_handler(devfreq, DEVFREQ_GOV_STOP, NULL);
+	if (devfreq->governor)
+		devfreq->governor->event_handler(devfreq,
+						 DEVFREQ_GOV_STOP, NULL);
 
 	if (devfreq->profile->exit)
 		devfreq->profile->exit(devfreq->dev.parent);
@@ -333,19 +417,20 @@ static void devfreq_dev_release(struct device *dev)
  * devfreq_add_device() - Add devfreq feature to the device
  * @dev:	the device to add devfreq feature.
  * @profile:	device-specific profile to run devfreq.
- * @governor:	the policy to choose frequency.
+ * @governor_name:	name of the policy to choose frequency.
  * @data:	private data for the governor. The devfreq framework does not
  *		touch this value.
  */
 struct devfreq *devfreq_add_device(struct device *dev,
 				   struct devfreq_dev_profile *profile,
-				   const struct devfreq_governor *governor,
+				   const char *governor_name,
 				   void *data)
 {
 	struct devfreq *devfreq;
+	struct devfreq_governor *governor;
 	int err = 0;
 
-	if (!dev || !profile || !governor) {
+	if (!dev || !profile || !governor_name) {
 		dev_err(dev, "%s: Invalid parameters.\n", __func__);
 		return ERR_PTR(-EINVAL);
 	}
@@ -373,11 +458,20 @@ struct devfreq *devfreq_add_device(struct device *dev,
 	devfreq->dev.class = devfreq_class;
 	devfreq->dev.release = devfreq_dev_release;
 	devfreq->profile = profile;
-	devfreq->governor = governor;
+	strncpy(devfreq->governor_name, governor_name, DEVFREQ_NAME_LEN);
 	devfreq->previous_freq = profile->initial_freq;
 	devfreq->data = data;
 	devfreq->nb.notifier_call = devfreq_notifier_call;
 
+	devfreq->trans_table =	devm_kzalloc(dev, sizeof(unsigned int) *
+						devfreq->profile->max_state *
+						devfreq->profile->max_state,
+						GFP_KERNEL);
+	devfreq->time_in_state = devm_kzalloc(dev, sizeof(unsigned int) *
+						devfreq->profile->max_state,
+						GFP_KERNEL);
+	devfreq->last_stat_updated = jiffies;
+
 	dev_set_name(&devfreq->dev, dev_name(dev));
 	err = device_register(&devfreq->dev);
 	if (err) {
@@ -390,10 +484,14 @@ struct devfreq *devfreq_add_device(struct device *dev,
 
 	mutex_lock(&devfreq_list_lock);
 	list_add(&devfreq->node, &devfreq_list);
-	mutex_unlock(&devfreq_list_lock);
 
-	err = devfreq->governor->event_handler(devfreq,
-				DEVFREQ_GOV_START, NULL);
+	governor = find_devfreq_governor(devfreq->governor_name);
+	if (!IS_ERR(governor))
+		devfreq->governor = governor;
+	if (devfreq->governor)
+		err = devfreq->governor->event_handler(devfreq,
+					DEVFREQ_GOV_START, NULL);
+	mutex_unlock(&devfreq_list_lock);
 	if (err) {
 		dev_err(dev, "%s: Unable to start governor for the device\n",
 			__func__);
@@ -436,6 +534,9 @@ int devfreq_suspend_device(struct devfreq *devfreq)
 	if (!devfreq)
 		return -EINVAL;
 
+	if (!devfreq->governor)
+		return 0;
+
 	return devfreq->governor->event_handler(devfreq,
 				DEVFREQ_GOV_SUSPEND, NULL);
 }
@@ -450,17 +551,207 @@ int devfreq_resume_device(struct devfreq *devfreq)
 	if (!devfreq)
 		return -EINVAL;
 
+	if (!devfreq->governor)
+		return 0;
+
 	return devfreq->governor->event_handler(devfreq,
 				DEVFREQ_GOV_RESUME, NULL);
 }
 EXPORT_SYMBOL(devfreq_resume_device);
 
+/**
+ * devfreq_add_governor() - Add devfreq governor
+ * @governor:	the devfreq governor to be added
+ */
+int devfreq_add_governor(struct devfreq_governor *governor)
+{
+	struct devfreq_governor *g;
+	struct devfreq *devfreq;
+	int err = 0;
+
+	if (!governor) {
+		pr_err("%s: Invalid parameters.\n", __func__);
+		return -EINVAL;
+	}
+
+	mutex_lock(&devfreq_list_lock);
+	g = find_devfreq_governor(governor->name);
+	if (!IS_ERR(g)) {
+		pr_err("%s: governor %s already registered\n", __func__,
+		       g->name);
+		err = -EINVAL;
+		goto err_out;
+	}
+
+	list_add(&governor->node, &devfreq_governor_list);
+
+	list_for_each_entry(devfreq, &devfreq_list, node) {
+		int ret = 0;
+		struct device *dev = devfreq->dev.parent;
+
+		if (!strncmp(devfreq->governor_name, governor->name,
+			     DEVFREQ_NAME_LEN)) {
+			/* The following should never occur */
+			if (devfreq->governor) {
+				dev_warn(dev,
+					 "%s: Governor %s already present\n",
+					 __func__, devfreq->governor->name);
+				ret = devfreq->governor->event_handler(devfreq,
+							DEVFREQ_GOV_STOP, NULL);
+				if (ret) {
+					dev_warn(dev,
+						 "%s: Governor %s stop = %d\n",
+						 __func__,
+						 devfreq->governor->name, ret);
+				}
+				/* Fall through */
+			}
+			devfreq->governor = governor;
+			ret = devfreq->governor->event_handler(devfreq,
+						DEVFREQ_GOV_START, NULL);
+			if (ret) {
+				dev_warn(dev, "%s: Governor %s start=%d\n",
+					 __func__, devfreq->governor->name,
+					 ret);
+			}
+		}
+	}
+
+err_out:
+	mutex_unlock(&devfreq_list_lock);
+
+	return err;
+}
+EXPORT_SYMBOL(devfreq_add_governor);
+
+/**
+ * devfreq_remove_device() - Remove devfreq feature from a device.
+ * @governor:	the devfreq governor to be removed
+ */
+int devfreq_remove_governor(struct devfreq_governor *governor)
+{
+	struct devfreq_governor *g;
+	struct devfreq *devfreq;
+	int err = 0;
+
+	if (!governor) {
+		pr_err("%s: Invalid parameters.\n", __func__);
+		return -EINVAL;
+	}
+
+	mutex_lock(&devfreq_list_lock);
+	g = find_devfreq_governor(governor->name);
+	if (IS_ERR(g)) {
+		pr_err("%s: governor %s not registered\n", __func__,
+		       g->name);
+		err = -EINVAL;
+		goto err_out;
+	}
+	list_for_each_entry(devfreq, &devfreq_list, node) {
+		int ret;
+		struct device *dev = devfreq->dev.parent;
+
+		if (!strncmp(devfreq->governor_name, governor->name,
+			     DEVFREQ_NAME_LEN)) {
+			/* we should have a devfreq governor! */
+			if (!devfreq->governor) {
+				dev_warn(dev, "%s: Governor %s NOT present\n",
+					 __func__, governor->name);
+				continue;
+				/* Fall through */
+			}
+			ret = devfreq->governor->event_handler(devfreq,
+						DEVFREQ_GOV_STOP, NULL);
+			if (ret) {
+				dev_warn(dev, "%s: Governor %s stop=%d\n",
+					 __func__, devfreq->governor->name,
+					 ret);
+			}
+			devfreq->governor = NULL;
+		}
+	}
+
+	list_del(&governor->node);
+err_out:
+	mutex_unlock(&devfreq_list_lock);
+
+	return err;
+}
+EXPORT_SYMBOL(devfreq_remove_governor);
+
 static ssize_t show_governor(struct device *dev,
 			     struct device_attribute *attr, char *buf)
 {
+	if (!to_devfreq(dev)->governor)
+		return -EINVAL;
+
 	return sprintf(buf, "%s\n", to_devfreq(dev)->governor->name);
 }
 
+static ssize_t store_governor(struct device *dev, struct device_attribute *attr,
+			      const char *buf, size_t count)
+{
+	struct devfreq *df = to_devfreq(dev);
+	int ret;
+	char str_governor[DEVFREQ_NAME_LEN + 1];
+	struct devfreq_governor *governor;
+
+	ret = sscanf(buf, "%" __stringify(DEVFREQ_NAME_LEN) "s", str_governor);
+	if (ret != 1)
+		return -EINVAL;
+
+	mutex_lock(&devfreq_list_lock);
+	governor = find_devfreq_governor(str_governor);
+	if (IS_ERR(governor)) {
+		ret = PTR_ERR(governor);
+		goto out;
+	}
+	if (df->governor == governor)
+		goto out;
+
+	if (df->governor) {
+		ret = df->governor->event_handler(df, DEVFREQ_GOV_STOP, NULL);
+		if (ret) {
+			dev_warn(dev, "%s: Governor %s not stopped(%d)\n",
+				 __func__, df->governor->name, ret);
+			goto out;
+		}
+	}
+	df->governor = governor;
+	strncpy(df->governor_name, governor->name, DEVFREQ_NAME_LEN);
+	ret = df->governor->event_handler(df, DEVFREQ_GOV_START, NULL);
+	if (ret)
+		dev_warn(dev, "%s: Governor %s not started(%d)\n",
+			 __func__, df->governor->name, ret);
+out:
+	mutex_unlock(&devfreq_list_lock);
+
+	if (!ret)
+		ret = count;
+	return ret;
+}
+static ssize_t show_available_governors(struct device *d,
+				    struct device_attribute *attr,
+				    char *buf)
+{
+	struct devfreq_governor *tmp_governor;
+	ssize_t count = 0;
+
+	mutex_lock(&devfreq_list_lock);
+	list_for_each_entry(tmp_governor, &devfreq_governor_list, node)
+		count += scnprintf(&buf[count], (PAGE_SIZE - count - 2),
+				   "%s ", tmp_governor->name);
+	mutex_unlock(&devfreq_list_lock);
+
+	/* Truncate the trailing space */
+	if (count)
+		count--;
+
+	count += sprintf(&buf[count], "\n");
+
+	return count;
+}
+
 static ssize_t show_freq(struct device *dev,
 			 struct device_attribute *attr, char *buf)
 {
@@ -494,6 +785,9 @@ static ssize_t store_polling_interval(struct device *dev,
 	unsigned int value;
 	int ret;
 
+	if (!df->governor)
+		return -EINVAL;
+
 	ret = sscanf(buf, "%u", &value);
 	if (ret != 1)
 		return -EINVAL;
@@ -570,14 +864,89 @@ static ssize_t show_max_freq(struct device *dev, struct device_attribute *attr,
 	return sprintf(buf, "%lu\n", to_devfreq(dev)->max_freq);
 }
 
+static ssize_t show_available_freqs(struct device *d,
+				    struct device_attribute *attr,
+				    char *buf)
+{
+	struct devfreq *df = to_devfreq(d);
+	struct device *dev = df->dev.parent;
+	struct opp *opp;
+	ssize_t count = 0;
+	unsigned long freq = 0;
+
+	rcu_read_lock();
+	do {
+		opp = opp_find_freq_ceil(dev, &freq);
+		if (IS_ERR(opp))
+			break;
+
+		count += scnprintf(&buf[count], (PAGE_SIZE - count - 2),
+				   "%lu ", freq);
+		freq++;
+	} while (1);
+	rcu_read_unlock();
+
+	/* Truncate the trailing space */
+	if (count)
+		count--;
+
+	count += sprintf(&buf[count], "\n");
+
+	return count;
+}
+
+static ssize_t show_trans_table(struct device *dev, struct device_attribute *attr,
+				char *buf)
+{
+	struct devfreq *devfreq = to_devfreq(dev);
+	ssize_t len;
+	int i, j, err;
+	unsigned int max_state = devfreq->profile->max_state;
+
+	err = devfreq_update_status(devfreq, devfreq->previous_freq);
+	if (err)
+		return 0;
+
+	len = sprintf(buf, "   From  :   To\n");
+	len += sprintf(buf + len, "         :");
+	for (i = 0; i < max_state; i++)
+		len += sprintf(buf + len, "%8u",
+				devfreq->profile->freq_table[i]);
+
+	len += sprintf(buf + len, "   time(ms)\n");
+
+	for (i = 0; i < max_state; i++) {
+		if (devfreq->profile->freq_table[i]
+					== devfreq->previous_freq) {
+			len += sprintf(buf + len, "*");
+		} else {
+			len += sprintf(buf + len, " ");
+		}
+		len += sprintf(buf + len, "%8u:",
+				devfreq->profile->freq_table[i]);
+		for (j = 0; j < max_state; j++)
+			len += sprintf(buf + len, "%8u",
+				devfreq->trans_table[(i * max_state) + j]);
+		len += sprintf(buf + len, "%10u\n",
+			jiffies_to_msecs(devfreq->time_in_state[i]));
+	}
+
+	len += sprintf(buf + len, "Total transition : %u\n",
+					devfreq->total_trans);
+	return len;
+}
+
 static struct device_attribute devfreq_attrs[] = {
-	__ATTR(governor, S_IRUGO, show_governor, NULL),
+	__ATTR(governor, S_IRUGO | S_IWUSR, show_governor, store_governor),
+	__ATTR(available_governors, S_IRUGO, show_available_governors, NULL),
 	__ATTR(cur_freq, S_IRUGO, show_freq, NULL),
+	__ATTR(available_frequencies, S_IRUGO, show_available_freqs, NULL),
 	__ATTR(target_freq, S_IRUGO, show_target_freq, NULL),
 	__ATTR(polling_interval, S_IRUGO | S_IWUSR, show_polling_interval,
 	       store_polling_interval),
 	__ATTR(min_freq, S_IRUGO | S_IWUSR, show_min_freq, store_min_freq),
 	__ATTR(max_freq, S_IRUGO | S_IWUSR, show_max_freq, store_max_freq),
+	__ATTR(trans_stat, S_IRUGO, show_trans_table, NULL),
 	{ },
 };
 

drivers/devfreq/exynos4_bus.c

@@ -987,7 +987,7 @@ static __devinit int exynos4_busfreq_probe(struct platform_device *pdev)
 	struct device *dev = &pdev->dev;
 	int err = 0;
 
-	data = kzalloc(sizeof(struct busfreq_data), GFP_KERNEL);
+	data = devm_kzalloc(&pdev->dev, sizeof(struct busfreq_data), GFP_KERNEL);
 	if (data == NULL) {
 		dev_err(dev, "Cannot allocate memory.\n");
 		return -ENOMEM;
@@ -1012,31 +1012,26 @@ static __devinit int exynos4_busfreq_probe(struct platform_device *pdev)
 		err = -EINVAL;
 	}
 	if (err)
-		goto err_regulator;
+		return err;
 
-	data->vdd_int = regulator_get(dev, "vdd_int");
+	data->vdd_int = devm_regulator_get(dev, "vdd_int");
 	if (IS_ERR(data->vdd_int)) {
 		dev_err(dev, "Cannot get the regulator \"vdd_int\"\n");
-		err = PTR_ERR(data->vdd_int);
-		goto err_regulator;
+		return PTR_ERR(data->vdd_int);
 	}
 	if (data->type == TYPE_BUSF_EXYNOS4x12) {
-		data->vdd_mif = regulator_get(dev, "vdd_mif");
+		data->vdd_mif = devm_regulator_get(dev, "vdd_mif");
 		if (IS_ERR(data->vdd_mif)) {
 			dev_err(dev, "Cannot get the regulator \"vdd_mif\"\n");
-			err = PTR_ERR(data->vdd_mif);
-			regulator_put(data->vdd_int);
-			goto err_regulator;
-
+			return PTR_ERR(data->vdd_mif);
 		}
 	}
 
 	opp = opp_find_freq_floor(dev, &exynos4_devfreq_profile.initial_freq);
 	if (IS_ERR(opp)) {
 		dev_err(dev, "Invalid initial frequency %lu kHz.\n",
-		       exynos4_devfreq_profile.initial_freq);
-		err = PTR_ERR(opp);
-		goto err_opp_add;
+			exynos4_devfreq_profile.initial_freq);
+		return PTR_ERR(opp);
 	}
 	data->curr_opp = opp;
 
@@ -1045,30 +1040,20 @@ static __devinit int exynos4_busfreq_probe(struct platform_device *pdev)
 	busfreq_mon_reset(data);
 
 	data->devfreq = devfreq_add_device(dev, &exynos4_devfreq_profile,
-					   &devfreq_simple_ondemand, NULL);
-	if (IS_ERR(data->devfreq)) {
-		err = PTR_ERR(data->devfreq);
-		goto err_opp_add;
-	}
+					   "simple_ondemand", NULL);
+	if (IS_ERR(data->devfreq))
+		return PTR_ERR(data->devfreq);
 
 	devfreq_register_opp_notifier(dev, data->devfreq);
 
 	err = register_pm_notifier(&data->pm_notifier);
 	if (err) {
 		dev_err(dev, "Failed to setup pm notifier\n");
-		goto err_devfreq_add;
+		devfreq_remove_device(data->devfreq);
+		return err;
 	}
 
 	return 0;
-err_devfreq_add:
-	devfreq_remove_device(data->devfreq);
-err_opp_add:
-	if (data->vdd_mif)
-		regulator_put(data->vdd_mif);
-	regulator_put(data->vdd_int);
-err_regulator:
-	kfree(data);
-	return err;
 }
 
 static __devexit int exynos4_busfreq_remove(struct platform_device *pdev)
@@ -1077,10 +1062,6 @@ static __devexit int exynos4_busfreq_remove(struct platform_device *pdev)
 
 	unregister_pm_notifier(&data->pm_notifier);
 	devfreq_remove_device(data->devfreq);
-	regulator_put(data->vdd_int);
-	if (data->vdd_mif)
-		regulator_put(data->vdd_mif);
-	kfree(data);
 
 	return 0;
 }

drivers/devfreq/governor.h

@@ -34,4 +34,8 @@ extern void devfreq_monitor_suspend(struct devfreq *devfreq);
 extern void devfreq_monitor_resume(struct devfreq *devfreq);
 extern void devfreq_interval_update(struct devfreq *devfreq,
 					unsigned int *delay);
+
+extern int devfreq_add_governor(struct devfreq_governor *governor);
+extern int devfreq_remove_governor(struct devfreq_governor *governor);
+
 #endif /* _GOVERNOR_H */

drivers/devfreq/governor_performance.c

@@ -10,6 +10,7 @@
  */
 
 #include <linux/devfreq.h>
+#include <linux/module.h>
 #include "governor.h"
 
 static int devfreq_performance_func(struct devfreq *df,
@@ -40,8 +41,27 @@ static int devfreq_performance_handler(struct devfreq *devfreq,
 	return ret;
 }
 
-const struct devfreq_governor devfreq_performance = {
+static struct devfreq_governor devfreq_performance = {
 	.name = "performance",
 	.get_target_freq = devfreq_performance_func,
 	.event_handler = devfreq_performance_handler,
 };
+
+static int __init devfreq_performance_init(void)
+{
+	return devfreq_add_governor(&devfreq_performance);
+}
+subsys_initcall(devfreq_performance_init);
+
+static void __exit devfreq_performance_exit(void)
+{
+	int ret;
+
+	ret = devfreq_remove_governor(&devfreq_performance);
+	if (ret)
+		pr_err("%s: failed remove governor %d\n", __func__, ret);
+
+	return;
+}
+module_exit(devfreq_performance_exit);
+MODULE_LICENSE("GPL");

drivers/devfreq/governor_powersave.c

@@ -10,6 +10,7 @@
  */
 
 #include <linux/devfreq.h>
+#include <linux/module.h>
 #include "governor.h"
 
 static int devfreq_powersave_func(struct devfreq *df,
@@ -37,8 +38,27 @@ static int devfreq_powersave_handler(struct devfreq *devfreq,
 	return ret;
 }
 
-const struct devfreq_governor devfreq_powersave = {
+static struct devfreq_governor devfreq_powersave = {
 	.name = "powersave",
 	.get_target_freq = devfreq_powersave_func,
 	.event_handler = devfreq_powersave_handler,
 };
+
+static int __init devfreq_powersave_init(void)
+{
+	return devfreq_add_governor(&devfreq_powersave);
+}
+subsys_initcall(devfreq_powersave_init);
+
+static void __exit devfreq_powersave_exit(void)
+{
+	int ret;
+
+	ret = devfreq_remove_governor(&devfreq_powersave);
+	if (ret)
+		pr_err("%s: failed remove governor %d\n", __func__, ret);
+
+	return;
+}
+module_exit(devfreq_powersave_exit);
+MODULE_LICENSE("GPL");

drivers/devfreq/governor_simpleondemand.c

@@ -10,6 +10,7 @@
  */
 
 #include <linux/errno.h>
+#include <linux/module.h>
 #include <linux/devfreq.h>
 #include <linux/math64.h>
 #include "governor.h"
@@ -120,8 +121,27 @@ static int devfreq_simple_ondemand_handler(struct devfreq *devfreq,
 	return 0;
 }
 
-const struct devfreq_governor devfreq_simple_ondemand = {
+static struct devfreq_governor devfreq_simple_ondemand = {
 	.name = "simple_ondemand",
 	.get_target_freq = devfreq_simple_ondemand_func,
 	.event_handler = devfreq_simple_ondemand_handler,
 };
+
+static int __init devfreq_simple_ondemand_init(void)
+{
+	return devfreq_add_governor(&devfreq_simple_ondemand);
+}
+subsys_initcall(devfreq_simple_ondemand_init);
+
+static void __exit devfreq_simple_ondemand_exit(void)
+{
+	int ret;
+
+	ret = devfreq_remove_governor(&devfreq_simple_ondemand);
+	if (ret)
+		pr_err("%s: failed remove governor %d\n", __func__, ret);
+
+	return;
+}
+module_exit(devfreq_simple_ondemand_exit);
+MODULE_LICENSE("GPL");

drivers/devfreq/governor_userspace.c

@@ -14,6 +14,7 @@
 #include <linux/devfreq.h>
 #include <linux/pm.h>
 #include <linux/mutex.h>
+#include <linux/module.h>
 #include "governor.h"
 
 struct userspace_data {
@@ -135,8 +136,27 @@ static int devfreq_userspace_handler(struct devfreq *devfreq,
 	return ret;
 }
 
-const struct devfreq_governor devfreq_userspace = {
+static struct devfreq_governor devfreq_userspace = {
 	.name = "userspace",
 	.get_target_freq = devfreq_userspace_func,
 	.event_handler = devfreq_userspace_handler,
 };
+
+static int __init devfreq_userspace_init(void)
+{
+	return devfreq_add_governor(&devfreq_userspace);
+}
+subsys_initcall(devfreq_userspace_init);
+
+static void __exit devfreq_userspace_exit(void)
+{
+	int ret;
+
+	ret = devfreq_remove_governor(&devfreq_userspace);
+	if (ret)
+		pr_err("%s: failed remove governor %d\n", __func__, ret);
+
+	return;
+}
+module_exit(devfreq_userspace_exit);
+MODULE_LICENSE("GPL");

include/linux/devfreq.h

@@ -25,12 +25,12 @@ struct devfreq;
  * struct devfreq_dev_status - Data given from devfreq user device to
  *			     governors. Represents the performance
  *			     statistics.
- * @total_time		The total time represented by this instance of
+ * @total_time:		The total time represented by this instance of
  *			devfreq_dev_status
- * @busy_time		The time that the device was working among the
+ * @busy_time:		The time that the device was working among the
  *			total_time.
- * @current_frequency	The operating frequency.
- * @private_data	An entry not specified by the devfreq framework.
+ * @current_frequency:	The operating frequency.
+ * @private_data:	An entry not specified by the devfreq framework.
  *			A device and a specific governor may have their
  *			own protocol with private_data. However, because
  *			this is governor-specific, a governor using this
@@ -54,25 +54,27 @@ struct devfreq_dev_status {
 
 /**
  * struct devfreq_dev_profile - Devfreq's user device profile
- * @initial_freq	The operating frequency when devfreq_add_device() is
+ * @initial_freq:	The operating frequency when devfreq_add_device() is
  *			called.
- * @polling_ms		The polling interval in ms. 0 disables polling.
- * @target		The device should set its operating frequency at
+ * @polling_ms:		The polling interval in ms. 0 disables polling.
+ * @target:		The device should set its operating frequency at
  *			freq or lowest-upper-than-freq value. If freq is
  *			higher than any operable frequency, set maximum.
  *			Before returning, target function should set
  *			freq at the current frequency.
  *			The "flags" parameter's possible values are
  *			explained above with "DEVFREQ_FLAG_*" macros.
- * @get_dev_status	The device should provide the current performance
+ * @get_dev_status:	The device should provide the current performance
  *			status to devfreq, which is used by governors.
- * @get_cur_freq	The device should provide the current frequency
+ * @get_cur_freq:	The device should provide the current frequency
  *			at which it is operating.
- * @exit		An optional callback that is called when devfreq
+ * @exit:		An optional callback that is called when devfreq
  *			is removing the devfreq object due to error or
  *			from devfreq_remove_device() call. If the user
  *			has registered devfreq->nb at a notifier-head,
  *			this is the time to unregister it.
+ * @freq_table:	Optional list of frequencies to support statistics.
+ * @max_state:	The size of freq_table.
  */
 struct devfreq_dev_profile {
 	unsigned long initial_freq;
@@ -83,18 +85,22 @@ struct devfreq_dev_profile {
 			      struct devfreq_dev_status *stat);
 	int (*get_cur_freq)(struct device *dev, unsigned long *freq);
 	void (*exit)(struct device *dev);
+
+	unsigned int *freq_table;
+	unsigned int max_state;
 };
 
 /**
  * struct devfreq_governor - Devfreq policy governor
- * @name		Governor's name
- * @get_target_freq	Returns desired operating frequency for the device.
+ * @node:		list node - contains registered devfreq governors
+ * @name:		Governor's name
+ * @get_target_freq:	Returns desired operating frequency for the device.
  *			Basically, get_target_freq will run
  *			devfreq_dev_profile.get_dev_status() to get the
  *			status of the device (load = busy_time / total_time).
  *			If no_central_polling is set, this callback is called
  *			only with update_devfreq() notified by OPP.
- * @event_handler       Callback for devfreq core framework to notify events
+ * @event_handler:      Callback for devfreq core framework to notify events
  *                      to governors. Events include per device governor
  *                      init and exit, opp changes out of devfreq, suspend
  *                      and resume of per device devfreq during device idle.
@@ -102,6 +108,8 @@ struct devfreq_dev_profile {
  * Note that the callbacks are called with devfreq->lock locked by devfreq.
  */
 struct devfreq_governor {
+	struct list_head node;
+
 	const char name[DEVFREQ_NAME_LEN];
 	int (*get_target_freq)(struct devfreq *this, unsigned long *freq);
 	int (*event_handler)(struct devfreq *devfreq,
@@ -110,23 +118,28 @@ struct devfreq_governor {
 
 /**
  * struct devfreq - Device devfreq structure
- * @node	list node - contains the devices with devfreq that have been
+ * @node:	list node - contains the devices with devfreq that have been
  *		registered.
- * @lock	a mutex to protect accessing devfreq.
- * @dev		device registered by devfreq class. dev.parent is the device
+ * @lock:	a mutex to protect accessing devfreq.
+ * @dev:	device registered by devfreq class. dev.parent is the device
  *		using devfreq.
- * @profile	device-specific devfreq profile
- * @governor	method how to choose frequency based on the usage.
- * @nb		notifier block used to notify devfreq object that it should
+ * @profile:	device-specific devfreq profile
+ * @governor:	method how to choose frequency based on the usage.
+ * @governor_name:	devfreq governor name for use with this devfreq
+ * @nb:		notifier block used to notify devfreq object that it should
  *		reevaluate operable frequencies. Devfreq users may use
  *		devfreq.nb to the corresponding register notifier call chain.
- * @work	delayed work for load monitoring.
- * @previous_freq	previously configured frequency value.
- * @data	Private data of the governor. The devfreq framework does not
+ * @work:	delayed work for load monitoring.
+ * @previous_freq:	previously configured frequency value.
+ * @data:	Private data of the governor. The devfreq framework does not
  *		touch this.
- * @min_freq	Limit minimum frequency requested by user (0: none)
- * @max_freq	Limit maximum frequency requested by user (0: none)
- * @stop_polling	 devfreq polling status of a device.
+ * @min_freq:	Limit minimum frequency requested by user (0: none)
+ * @max_freq:	Limit maximum frequency requested by user (0: none)
+ * @stop_polling:	 devfreq polling status of a device.
+ * @total_trans:	Number of devfreq transitions
+ * @trans_table:	Statistics of devfreq transitions
+ * @time_in_state:	Statistics of devfreq states
+ * @last_stat_updated:	The last time stat updated
  *
  * This structure stores the devfreq information for a give device.
  *
@@ -143,6 +156,7 @@ struct devfreq {
 	struct device dev;
 	struct devfreq_dev_profile *profile;
 	const struct devfreq_governor *governor;
+	char governor_name[DEVFREQ_NAME_LEN];
 	struct notifier_block nb;
 	struct delayed_work work;
 
@@ -153,12 +167,18 @@ struct devfreq {
 	unsigned long min_freq;
 	unsigned long max_freq;
 	bool stop_polling;
+
+	/* information for device freqeuncy transition */
+	unsigned int total_trans;
+	unsigned int *trans_table;
+	unsigned long *time_in_state;
+	unsigned long last_stat_updated;
 };
 
 #if defined(CONFIG_PM_DEVFREQ)
 extern struct devfreq *devfreq_add_device(struct device *dev,
 				  struct devfreq_dev_profile *profile,
-				  const struct devfreq_governor *governor,
+				  const char *governor_name,
 				  void *data);
 extern int devfreq_remove_device(struct devfreq *devfreq);
 extern int devfreq_suspend_device(struct devfreq *devfreq);
@@ -172,23 +192,13 @@ extern int devfreq_register_opp_notifier(struct device *dev,
 extern int devfreq_unregister_opp_notifier(struct device *dev,
 					   struct devfreq *devfreq);
 
-#ifdef CONFIG_DEVFREQ_GOV_POWERSAVE
-extern const struct devfreq_governor devfreq_powersave;
-#endif
-#ifdef CONFIG_DEVFREQ_GOV_PERFORMANCE
-extern const struct devfreq_governor devfreq_performance;
-#endif
-#ifdef CONFIG_DEVFREQ_GOV_USERSPACE
-extern const struct devfreq_governor devfreq_userspace;
-#endif
 #ifdef CONFIG_DEVFREQ_GOV_SIMPLE_ONDEMAND
-extern const struct devfreq_governor devfreq_simple_ondemand;
 /**
  * struct devfreq_simple_ondemand_data - void *data fed to struct devfreq
  *	and devfreq_add_device
- * @ upthreshold	If the load is over this value, the frequency jumps.
+ * @upthreshold:	If the load is over this value, the frequency jumps.
  *			Specify 0 to use the default. Valid value = 0 to 100.
- * @ downdifferential	If the load is under upthreshold - downdifferential,
+ * @downdifferential:	If the load is under upthreshold - downdifferential,
  *			the governor may consider slowing the frequency down.
  *			Specify 0 to use the default. Valid value = 0 to 100.
  *			downdifferential < upthreshold must hold.
@@ -205,7 +215,7 @@ struct devfreq_simple_ondemand_data {
 #else /* !CONFIG_PM_DEVFREQ */
 static struct devfreq *devfreq_add_device(struct device *dev,
 					  struct devfreq_dev_profile *profile,
-					  struct devfreq_governor *governor,
+					  const char *governor_name,
 					  void *data)
 {
 	return NULL;
@@ -244,11 +254,6 @@ static int devfreq_unregister_opp_notifier(struct device *dev,
 	return -EINVAL;
 }
 
-#define devfreq_powersave	NULL
-#define devfreq_performance	NULL
-#define devfreq_userspace	NULL
-#define devfreq_simple_ondemand	NULL
-
 #endif /* CONFIG_PM_DEVFREQ */
 
 #endif /* __LINUX_DEVFREQ_H__ */