1 files changed, 209 insertions, 86 deletions

diff --git a/drivers/thermal/cpu_cooling.c b/drivers/thermal/cpu_cooling.c
index 8dc44cbb3e09..c94bf2e5de62 100644
--- a/drivers/thermal/cpu_cooling.c
+++ b/drivers/thermal/cpu_cooling.c
@@ -20,10 +20,8 @@
  *
  * ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
  */
-#include <linux/kernel.h>
 #include <linux/module.h>
 #include <linux/thermal.h>
-#include <linux/platform_device.h>
 #include <linux/cpufreq.h>
 #include <linux/err.h>
 #include <linux/slab.h>
@@ -31,21 +29,19 @@
 #include <linux/cpu_cooling.h>
 
 /**
- * struct cpufreq_cooling_device
+ * struct cpufreq_cooling_device - data for cooling device with cpufreq
  * @id: unique integer value corresponding to each cpufreq_cooling_device
  *	registered.
- * @cool_dev: thermal_cooling_device pointer to keep track of the the
- *	egistered cooling device.
+ * @cool_dev: thermal_cooling_device pointer to keep track of the
+ *	registered cooling device.
  * @cpufreq_state: integer value representing the current state of cpufreq
  *	cooling	devices.
  * @cpufreq_val: integer value representing the absolute value of the clipped
  *	frequency.
  * @allowed_cpus: all the cpus involved for this cpufreq_cooling_device.
- * @node: list_head to link all cpufreq_cooling_device together.
  *
  * This structure is required for keeping information of each
- * cpufreq_cooling_device registered as a list whose head is represented by
- * cooling_cpufreq_list. In order to prevent corruption of this list a
+ * cpufreq_cooling_device registered. In order to prevent corruption of this a
  * mutex lock cooling_cpufreq_lock is used.
  */
 struct cpufreq_cooling_device {
@@ -54,9 +50,7 @@ struct cpufreq_cooling_device {
 	unsigned int cpufreq_state;
 	unsigned int cpufreq_val;
 	struct cpumask allowed_cpus;
-	struct list_head node;
 };
-static LIST_HEAD(cooling_cpufreq_list);
 static DEFINE_IDR(cpufreq_idr);
 static DEFINE_MUTEX(cooling_cpufreq_lock);
 
@@ -70,6 +64,11 @@ static struct cpufreq_cooling_device *notify_device;
  * get_idr - function to get a unique id.
  * @idr: struct idr * handle used to create a id.
  * @id: int * value generated by this function.
+ *
+ * This function will populate @id with an unique
+ * id, using the idr API.
+ *
+ * Return: 0 on success, an error code on failure.
  */
 static int get_idr(struct idr *idr, int *id)
 {
@@ -81,6 +80,7 @@ static int get_idr(struct idr *idr, int *id)
 	if (unlikely(ret < 0))
 		return ret;
 	*id = ret;
+
 	return 0;
 }
 
@@ -99,63 +99,162 @@ static void release_idr(struct idr *idr, int id)
 /* Below code defines functions to be used for cpufreq as cooling device */
 
 /**
- * is_cpufreq_valid - function to check if a cpu has frequency transition policy.
+ * is_cpufreq_valid - function to check frequency transitioning capability.
  * @cpu: cpu for which check is needed.
+ *
+ * This function will check the current state of the system if
+ * it is capable of changing the frequency for a given @cpu.
+ *
+ * Return: 0 if the system is not currently capable of changing
+ * the frequency of given cpu. !0 in case the frequency is changeable.
  */
 static int is_cpufreq_valid(int cpu)
 {
 	struct cpufreq_policy policy;
+
 	return !cpufreq_get_policy(&policy, cpu);
 }
 
+enum cpufreq_cooling_property {
+	GET_LEVEL,
+	GET_FREQ,
+	GET_MAXL,
+};
+
 /**
- * get_cpu_frequency - get the absolute value of frequency from level.
- * @cpu: cpu for which frequency is fetched.
- * @level: level of frequency, equals cooling state of cpu cooling device
- *	e.g level=0 --> 1st MAX FREQ, level=1 ---> 2nd MAX FREQ, .... etc
+ * get_property - fetch a property of interest for a give cpu.
+ * @cpu: cpu for which the property is required
+ * @input: query parameter
+ * @output: query return
+ * @property: type of query (frequency, level, max level)
+ *
+ * This is the common function to
+ * 1. get maximum cpu cooling states
+ * 2. translate frequency to cooling state
+ * 3. translate cooling state to frequency
+ * Note that the code may be not in good shape
+ * but it is written in this way in order to:
+ * a) reduce duplicate code as most of the code can be shared.
+ * b) make sure the logic is consistent when translating between
+ *    cooling states and frequencies.
+ *
+ * Return: 0 on success, -EINVAL when invalid parameters are passed.
  */
-static unsigned int get_cpu_frequency(unsigned int cpu, unsigned long level)
+static int get_property(unsigned int cpu, unsigned long input,
+			unsigned int *output,
+			enum cpufreq_cooling_property property)
 {
-	int ret = 0, i = 0;
-	unsigned long level_index;
-	bool descend = false;
+	int i, j;
+	unsigned long max_level = 0, level = 0;
+	unsigned int freq = CPUFREQ_ENTRY_INVALID;
+	int descend = -1;
 	struct cpufreq_frequency_table *table =
 					cpufreq_frequency_get_table(cpu);
+
+	if (!output)
+		return -EINVAL;
+
 	if (!table)
-		return ret;
+		return -EINVAL;
 
-	while (table[i].frequency != CPUFREQ_TABLE_END) {
+	for (i = 0; table[i].frequency != CPUFREQ_TABLE_END; i++) {
+		/* ignore invalid entries */
 		if (table[i].frequency == CPUFREQ_ENTRY_INVALID)
 			continue;
 
-		/*check if table in ascending or descending order*/
-		if ((table[i + 1].frequency != CPUFREQ_TABLE_END) &&
-			(table[i + 1].frequency < table[i].frequency)
-			&& !descend) {
-			descend = true;
-		}
+		/* ignore duplicate entry */
+		if (freq == table[i].frequency)
+			continue;
+
+		/* get the frequency order */
+		if (freq != CPUFREQ_ENTRY_INVALID && descend != -1)
+			descend = !!(freq > table[i].frequency);
 
-		/*return if level matched and table in descending order*/
-		if (descend && i == level)
-			return table[i].frequency;
-		i++;
+		freq = table[i].frequency;
+		max_level++;
 	}
-	i--;
 
-	if (level > i || descend)
-		return ret;
-	level_index = i - level;
+	/* get max level */
+	if (property == GET_MAXL) {
+		*output = (unsigned int)max_level;
+		return 0;
+	}
 
-	/*Scan the table in reverse order and match the level*/
-	while (i >= 0) {
+	if (property == GET_FREQ)
+		level = descend ? input : (max_level - input - 1);
+
+	for (i = 0, j = 0; table[i].frequency != CPUFREQ_TABLE_END; i++) {
+		/* ignore invalid entry */
 		if (table[i].frequency == CPUFREQ_ENTRY_INVALID)
 			continue;
-		/*return if level matched*/
-		if (i == level_index)
-			return table[i].frequency;
-		i--;
+
+		/* ignore duplicate entry */
+		if (freq == table[i].frequency)
+			continue;
+
+		/* now we have a valid frequency entry */
+		freq = table[i].frequency;
+
+		if (property == GET_LEVEL && (unsigned int)input == freq) {
+			/* get level by frequency */
+			*output = descend ? j : (max_level - j - 1);
+			return 0;
+		}
+		if (property == GET_FREQ && level == j) {
+			/* get frequency by level */
+			*output = freq;
+			return 0;
+		}
+		j++;
 	}
-	return ret;
+
+	return -EINVAL;
+}
+
+/**
+ * cpufreq_cooling_get_level - for a give cpu, return the cooling level.
+ * @cpu: cpu for which the level is required
+ * @freq: the frequency of interest
+ *
+ * This function will match the cooling level corresponding to the
+ * requested @freq and return it.
+ *
+ * Return: The matched cooling level on success or THERMAL_CSTATE_INVALID
+ * otherwise.
+ */
+unsigned long cpufreq_cooling_get_level(unsigned int cpu, unsigned int freq)
+{
+	unsigned int val;
+
+	if (get_property(cpu, (unsigned long)freq, &val, GET_LEVEL))
+		return THERMAL_CSTATE_INVALID;
+
+	return (unsigned long)val;
+}
+EXPORT_SYMBOL_GPL(cpufreq_cooling_get_level);
+
+/**
+ * get_cpu_frequency - get the absolute value of frequency from level.
+ * @cpu: cpu for which frequency is fetched.
+ * @level: cooling level
+ *
+ * This function matches cooling level with frequency. Based on a cooling level
+ * of frequency, equals cooling state of cpu cooling device, it will return
+ * the corresponding frequency.
+ *	e.g level=0 --> 1st MAX FREQ, level=1 ---> 2nd MAX FREQ, .... etc
+ *
+ * Return: 0 on error, the corresponding frequency otherwise.
+ */
+static unsigned int get_cpu_frequency(unsigned int cpu, unsigned long level)
+{
+	int ret = 0;
+	unsigned int freq;
+
+	ret = get_property(cpu, level, &freq, GET_FREQ);
+	if (ret)
+		return 0;
+
+	return freq;
 }
 
 /**
@@ -163,13 +262,19 @@ static unsigned int get_cpu_frequency(unsigned int cpu, unsigned long level)
  * @cpufreq_device: cpufreq_cooling_device pointer containing frequency
  *	clipping data.
  * @cooling_state: value of the cooling state.
+ *
+ * Function used to make sure the cpufreq layer is aware of current thermal
+ * limits. The limits are applied by updating the cpufreq policy.
+ *
+ * Return: 0 on success, an error code otherwise (-EINVAL in case wrong
+ * cooling state).
  */
 static int cpufreq_apply_cooling(struct cpufreq_cooling_device *cpufreq_device,
-				unsigned long cooling_state)
+				 unsigned long cooling_state)
 {
 	unsigned int cpuid, clip_freq;
-	struct cpumask *maskPtr = &cpufreq_device->allowed_cpus;
-	unsigned int cpu = cpumask_any(maskPtr);
+	struct cpumask *mask = &cpufreq_device->allowed_cpus;
+	unsigned int cpu = cpumask_any(mask);
 
 
 	/* Check if the old cooling action is same as new cooling action */
@@ -184,7 +289,7 @@ static int cpufreq_apply_cooling(struct cpufreq_cooling_device *cpufreq_device,
 	cpufreq_device->cpufreq_val = clip_freq;
 	notify_device = cpufreq_device;
 
-	for_each_cpu(cpuid, maskPtr) {
+	for_each_cpu(cpuid, mask) {
 		if (is_cpufreq_valid(cpuid))
 			cpufreq_update_policy(cpuid);
 	}
@@ -199,9 +304,15 @@ static int cpufreq_apply_cooling(struct cpufreq_cooling_device *cpufreq_device,
  * @nb:	struct notifier_block * with callback info.
  * @event: value showing cpufreq event for which this function invoked.
  * @data: callback-specific data
+ *
+ * Callback to highjack the notification on cpufreq policy transition.
+ * Every time there is a change in policy, we will intercept and
+ * update the cpufreq policy with thermal constraints.
+ *
+ * Return: 0 (success)
  */
 static int cpufreq_thermal_notifier(struct notifier_block *nb,
-					unsigned long event, void *data)
+				    unsigned long event, void *data)
 {
 	struct cpufreq_policy *policy = data;
 	unsigned long max_freq = 0;
@@ -212,7 +323,7 @@ static int cpufreq_thermal_notifier(struct notifier_block *nb,
 	if (cpumask_test_cpu(policy->cpu, &notify_device->allowed_cpus))
 		max_freq = notify_device->cpufreq_val;
 
-	/* Never exceed user_policy.max*/
+	/* Never exceed user_policy.max */
 	if (max_freq > policy->user_policy.max)
 		max_freq = policy->user_policy.max;
 
@@ -222,50 +333,46 @@ static int cpufreq_thermal_notifier(struct notifier_block *nb,
 	return 0;
 }
 
-/*
- * cpufreq cooling device callback functions are defined below
- */
+/* cpufreq cooling device callback functions are defined below */
 
 /**
  * cpufreq_get_max_state - callback function to get the max cooling state.
  * @cdev: thermal cooling device pointer.
  * @state: fill this variable with the max cooling state.
+ *
+ * Callback for the thermal cooling device to return the cpufreq
+ * max cooling state.
+ *
+ * Return: 0 on success, an error code otherwise.
  */
 static int cpufreq_get_max_state(struct thermal_cooling_device *cdev,
 				 unsigned long *state)
 {
 	struct cpufreq_cooling_device *cpufreq_device = cdev->devdata;
-	struct cpumask *maskPtr = &cpufreq_device->allowed_cpus;
+	struct cpumask *mask = &cpufreq_device->allowed_cpus;
 	unsigned int cpu;
-	struct cpufreq_frequency_table *table;
-	unsigned long count = 0;
-	int i = 0;
-
-	cpu = cpumask_any(maskPtr);
-	table = cpufreq_frequency_get_table(cpu);
-	if (!table) {
-		*state = 0;
-		return 0;
-	}
+	unsigned int count = 0;
+	int ret;
 
-	for (i = 0; (table[i].frequency != CPUFREQ_TABLE_END); i++) {
-		if (table[i].frequency == CPUFREQ_ENTRY_INVALID)
-			continue;
-		count++;
-	}
+	cpu = cpumask_any(mask);
 
-	if (count > 0) {
-		*state = --count;
-		return 0;
-	}
+	ret = get_property(cpu, 0, &count, GET_MAXL);
 
-	return -EINVAL;
+	if (count > 0)
+		*state = count;
+
+	return ret;
 }
 
 /**
  * cpufreq_get_cur_state - callback function to get the current cooling state.
  * @cdev: thermal cooling device pointer.
  * @state: fill this variable with the current cooling state.
+ *
+ * Callback for the thermal cooling device to return the cpufreq
+ * current cooling state.
+ *
+ * Return: 0 on success, an error code otherwise.
  */
 static int cpufreq_get_cur_state(struct thermal_cooling_device *cdev,
 				 unsigned long *state)
@@ -273,6 +380,7 @@ static int cpufreq_get_cur_state(struct thermal_cooling_device *cdev,
 	struct cpufreq_cooling_device *cpufreq_device = cdev->devdata;
 
 	*state = cpufreq_device->cpufreq_state;
+
 	return 0;
 }
 
@@ -280,6 +388,11 @@ static int cpufreq_get_cur_state(struct thermal_cooling_device *cdev,
  * cpufreq_set_cur_state - callback function to set the current cooling state.
  * @cdev: thermal cooling device pointer.
  * @state: set this variable to the current cooling state.
+ *
+ * Callback for the thermal cooling device to change the cpufreq
+ * current cooling state.
+ *
+ * Return: 0 on success, an error code otherwise.
  */
 static int cpufreq_set_cur_state(struct thermal_cooling_device *cdev,
 				 unsigned long state)
@@ -304,9 +417,16 @@ static struct notifier_block thermal_cpufreq_notifier_block = {
 /**
  * cpufreq_cooling_register - function to create cpufreq cooling device.
  * @clip_cpus: cpumask of cpus where the frequency constraints will happen.
+ *
+ * This interface function registers the cpufreq cooling device with the name
+ * "thermal-cpufreq-%x". This api can support multiple instances of cpufreq
+ * cooling devices.
+ *
+ * Return: a valid struct thermal_cooling_device pointer on success,
+ * on failure, it returns a corresponding ERR_PTR().
  */
-struct thermal_cooling_device *cpufreq_cooling_register(
-	const struct cpumask *clip_cpus)
+struct thermal_cooling_device *
+cpufreq_cooling_register(const struct cpumask *clip_cpus)
 {
 	struct thermal_cooling_device *cool_dev;
 	struct cpufreq_cooling_device *cpufreq_dev = NULL;
@@ -315,9 +435,9 @@ struct thermal_cooling_device *cpufreq_cooling_register(
 	int ret = 0, i;
 	struct cpufreq_policy policy;
 
-	/*Verify that all the clip cpus have same freq_min, freq_max limit*/
+	/* Verify that all the clip cpus have same freq_min, freq_max limit */
 	for_each_cpu(i, clip_cpus) {
-		/*continue if cpufreq policy not found and not return error*/
+		/* continue if cpufreq policy not found and not return error */
 		if (!cpufreq_get_policy(&policy, i))
 			continue;
 		if (min == 0 && max == 0) {
@@ -325,12 +445,12 @@ struct thermal_cooling_device *cpufreq_cooling_register(
 			max = policy.cpuinfo.max_freq;
 		} else {
 			if (min != policy.cpuinfo.min_freq ||
-				max != policy.cpuinfo.max_freq)
+			    max != policy.cpuinfo.max_freq)
 				return ERR_PTR(-EINVAL);
 		}
 	}
 	cpufreq_dev = kzalloc(sizeof(struct cpufreq_cooling_device),
-			GFP_KERNEL);
+			      GFP_KERNEL);
 	if (!cpufreq_dev)
 		return ERR_PTR(-ENOMEM);
 
@@ -342,10 +462,11 @@ struct thermal_cooling_device *cpufreq_cooling_register(
 		return ERR_PTR(-EINVAL);
 	}
 
-	sprintf(dev_name, "thermal-cpufreq-%d", cpufreq_dev->id);
+	snprintf(dev_name, sizeof(dev_name), "thermal-cpufreq-%d",
+		 cpufreq_dev->id);
 
 	cool_dev = thermal_cooling_device_register(dev_name, cpufreq_dev,
-						&cpufreq_cooling_ops);
+						   &cpufreq_cooling_ops);
 	if (!cool_dev) {
 		release_idr(&cpufreq_idr, cpufreq_dev->id);
 		kfree(cpufreq_dev);
@@ -358,17 +479,20 @@ struct thermal_cooling_device *cpufreq_cooling_register(
 	/* Register the notifier for first cpufreq cooling device */
 	if (cpufreq_dev_count == 0)
 		cpufreq_register_notifier(&thermal_cpufreq_notifier_block,
-						CPUFREQ_POLICY_NOTIFIER);
+					  CPUFREQ_POLICY_NOTIFIER);
 	cpufreq_dev_count++;
 
 	mutex_unlock(&cooling_cpufreq_lock);
+
 	return cool_dev;
 }
-EXPORT_SYMBOL(cpufreq_cooling_register);
+EXPORT_SYMBOL_GPL(cpufreq_cooling_register);
 
 /**
  * cpufreq_cooling_unregister - function to remove cpufreq cooling device.
  * @cdev: thermal cooling device pointer.
+ *
+ * This interface function unregisters the "thermal-cpufreq-%x" cooling device.
  */
 void cpufreq_cooling_unregister(struct thermal_cooling_device *cdev)
 {
@@ -378,14 +502,13 @@ void cpufreq_cooling_unregister(struct thermal_cooling_device *cdev)
 	cpufreq_dev_count--;
 
 	/* Unregister the notifier for the last cpufreq cooling device */
-	if (cpufreq_dev_count == 0) {
+	if (cpufreq_dev_count == 0)
 		cpufreq_unregister_notifier(&thermal_cpufreq_notifier_block,
-					CPUFREQ_POLICY_NOTIFIER);
-	}
+					    CPUFREQ_POLICY_NOTIFIER);
 	mutex_unlock(&cooling_cpufreq_lock);
 
 	thermal_cooling_device_unregister(cpufreq_dev->cool_dev);
 	release_idr(&cpufreq_idr, cpufreq_dev->id);
 	kfree(cpufreq_dev);
 }
-EXPORT_SYMBOL(cpufreq_cooling_unregister);
+EXPORT_SYMBOL_GPL(cpufreq_cooling_unregister);