[v2,3/7] thermal: cpu_cooling: implement the power cooling device API
diff mbox

Message ID 1424977233-15965-4-git-send-email-javi.merino@arm.com
State Accepted
Delegated to: Eduardo Valentin
Headers show

Commit Message

Javi Merino Feb. 26, 2015, 7 p.m. UTC
Add a basic power model to the cpu cooling device to implement the
power cooling device API.  The power model uses the current frequency,
current load and OPPs for the power calculations.  The cpus must have
registered their OPPs using the OPP library.

Cc: Zhang Rui <rui.zhang@intel.com>
Cc: Eduardo Valentin <edubezval@gmail.com>
Signed-off-by: Kapileshwar Singh <kapileshwar.singh@arm.com>
Signed-off-by: Punit Agrawal <punit.agrawal@arm.com>
Signed-off-by: Javi Merino <javi.merino@arm.com>
---
 Documentation/thermal/cpu-cooling-api.txt | 156 +++++++-
 drivers/thermal/cpu_cooling.c             | 583 +++++++++++++++++++++++++++++-
 include/linux/cpu_cooling.h               |  39 ++
 3 files changed, 760 insertions(+), 18 deletions(-)

Patch
diff mbox

diff --git a/Documentation/thermal/cpu-cooling-api.txt b/Documentation/thermal/cpu-cooling-api.txt
index 753e47cc2e20..71653584cd03 100644
--- a/Documentation/thermal/cpu-cooling-api.txt
+++ b/Documentation/thermal/cpu-cooling-api.txt
@@ -36,8 +36,162 @@  the user. The registration APIs returns the cooling device pointer.
     np: pointer to the cooling device device tree node
     clip_cpus: cpumask of cpus where the frequency constraints will happen.
 
-1.1.3 void cpufreq_cooling_unregister(struct thermal_cooling_device *cdev)
+1.1.3 struct thermal_cooling_device *cpufreq_power_cooling_register(
+    const struct cpumask *clip_cpus, u32 capacitance,
+    get_static_t plat_static_func)
+
+Similar to cpufreq_cooling_register, this function registers a cpufreq
+cooling device.  Using this function, the cooling device will
+implement the power extensions by using a simple cpu power model.  The
+cpus must have registered their OPPs using the OPP library.
+
+The additional parameters are needed for the power model (See 2. Power
+models).  "capacitance" is the dynamic power coefficient (See 2.1
+Dynamic power).  "plat_static_func" is a function to calculate the
+static power consumed by these cpus (See 2.2 Static power).
+
+1.1.4 struct thermal_cooling_device *of_cpufreq_power_cooling_register(
+    struct device_node *np, const struct cpumask *clip_cpus, u32 capacitance,
+    get_static_t plat_static_func)
+
+Similar to cpufreq_power_cooling_register, this function register a
+cpufreq cooling device with power extensions using the device tree
+information supplied by the np parameter.
+
+1.1.5 void cpufreq_cooling_unregister(struct thermal_cooling_device *cdev)
 
     This interface function unregisters the "thermal-cpufreq-%x" cooling device.
 
     cdev: Cooling device pointer which has to be unregistered.
+
+2. Power models
+
+The power API registration functions provide a simple power model for
+CPUs.  The current power is calculated as dynamic + (optionally)
+static power.  This power model requires that the operating-points of
+the CPUs are registered using the kernel's opp library and the
+`cpufreq_frequency_table` is assigned to the `struct device` of the
+cpu.  If you are using CONFIG_CPUFREQ_DT then the
+`cpufreq_frequency_table` should already be assigned to the cpu
+device.
+
+The `plat_static_func` parameter of `cpufreq_power_cooling_register()`
+and `of_cpufreq_power_cooling_register()` is optional.  If you don't
+provide it, only dynamic power will be considered.
+
+2.1 Dynamic power
+
+The dynamic power consumption of a processor depends on many factors.
+For a given processor implementation the primary factors are:
+
+- The time the processor spends running, consuming dynamic power, as
+  compared to the time in idle states where dynamic consumption is
+  negligible.  Herein we refer to this as 'utilisation'.
+- The voltage and frequency levels as a result of DVFS.  The DVFS
+  level is a dominant factor governing power consumption.
+- In running time the 'execution' behaviour (instruction types, memory
+  access patterns and so forth) causes, in most cases, a second order
+  variation.  In pathological cases this variation can be significant,
+  but typically it is of a much lesser impact than the factors above.
+
+A high level dynamic power consumption model may then be represented as:
+
+Pdyn = f(run) * Voltage^2 * Frequency * Utilisation
+
+f(run) here represents the described execution behaviour and its
+result has a units of Watts/Hz/Volt^2 (this often expressed in
+mW/MHz/uVolt^2)
+
+The detailed behaviour for f(run) could be modelled on-line.  However,
+in practice, such an on-line model has dependencies on a number of
+implementation specific processor support and characterisation
+factors.  Therefore, in initial implementation that contribution is
+represented as a constant coefficient.  This is a simplification
+consistent with the relative contribution to overall power variation.
+
+In this simplified representation our model becomes:
+
+Pdyn = Capacitance * Voltage^2 * Frequency * Utilisation
+
+Where `capacitance` is a constant that represents an indicative
+running time dynamic power coefficient in fundamental units of
+mW/MHz/uVolt^2.  Typical values for mobile CPUs might lie in range
+from 100 to 500.  For reference, the approximate values for the SoC in
+ARM's Juno Development Platform are 530 for the Cortex-A57 cluster and
+140 for the Cortex-A53 cluster.
+
+
+2.2 Static power
+
+Static leakage power consumption depends on a number of factors.  For a
+given circuit implementation the primary factors are:
+
+- Time the circuit spends in each 'power state'
+- Temperature
+- Operating voltage
+- Process grade
+
+The time the circuit spends in each 'power state' for a given
+evaluation period at first order means OFF or ON.  However,
+'retention' states can also be supported that reduce power during
+inactive periods without loss of context.
+
+Note: The visibility of state entries to the OS can vary, according to
+platform specifics, and this can then impact the accuracy of a model
+based on OS state information alone.  It might be possible in some
+cases to extract more accurate information from system resources.
+
+The temperature, operating voltage and process 'grade' (slow to fast)
+of the circuit are all significant factors in static leakage power
+consumption.  All of these have complex relationships to static power.
+
+Circuit implementation specific factors include the chosen silicon
+process as well as the type, number and size of transistors in both
+the logic gates and any RAM elements included.
+
+The static power consumption modelling must take into account the
+power managed regions that are implemented.  Taking the example of an
+ARM processor cluster, the modelling would take into account whether
+each CPU can be powered OFF separately or if only a single power
+region is implemented for the complete cluster.
+
+In one view, there are others, a static power consumption model can
+then start from a set of reference values for each power managed
+region (e.g. CPU, Cluster/L2) in each state (e.g. ON, OFF) at an
+arbitrary process grade, voltage and temperature point.  These values
+are then scaled for all of the following: the time in each state, the
+process grade, the current temperature and the operating voltage.
+However, since both implementation specific and complex relationships
+dominate the estimate, the appropriate interface to the model from the
+cpu cooling device is to provide a function callback that calculates
+the static power in this platform.  When registering the cpu cooling
+device pass a function pointer that follows the `get_static_t`
+prototype:
+
+    int plat_get_static(cpumask_t *cpumask, int interval,
+                        unsigned long voltage, u32 &power);
+
+`cpumask` is the cpumask of the cpus involved in the calculation.
+`voltage` is the voltage at which they are operating.  The function
+should calculate the average static power for the last `interval`
+milliseconds.  It returns 0 on success, -E* on error.  If it
+succeeds, it should store the static power in `power`.  Reading the
+temperature of the cpus described by `cpumask` is left for
+plat_get_static() to do as the platform knows best which thermal
+sensor is closest to the cpu.
+
+If `plat_static_func` is NULL, static power is considered to be
+negligible for this platform and only dynamic power is considered.
+
+The platform specific callback can then use any combination of tables
+and/or equations to permute the estimated value.  Process grade
+information is not passed to the model since access to such data, from
+on-chip measurement capability or manufacture time data, is platform
+specific.
+
+Note: the significance of static power for CPUs in comparison to
+dynamic power is highly dependent on implementation.  Given the
+potential complexity in implementation, the importance and accuracy of
+its inclusion when using cpu cooling devices should be assessed on a
+case by case basis.
+
diff --git a/drivers/thermal/cpu_cooling.c b/drivers/thermal/cpu_cooling.c
index f65f0d109fc8..ba23150c7bde 100644
--- a/drivers/thermal/cpu_cooling.c
+++ b/drivers/thermal/cpu_cooling.c
@@ -26,6 +26,7 @@ 
 #include <linux/thermal.h>
 #include <linux/cpufreq.h>
 #include <linux/err.h>
+#include <linux/pm_opp.h>
 #include <linux/slab.h>
 #include <linux/cpu.h>
 #include <linux/cpu_cooling.h>
@@ -45,6 +46,19 @@ 
  */
 
 /**
+ * struct power_table - frequency to power conversion
+ * @frequency:	frequency in KHz
+ * @power:	power in mW
+ *
+ * This structure is built when the cooling device registers and helps
+ * in translating frequency to power and viceversa.
+ */
+struct power_table {
+	u32 frequency;
+	u32 power;
+};
+
+/**
  * struct cpufreq_cooling_device - data for cooling device with cpufreq
  * @id: unique integer value corresponding to each cpufreq_cooling_device
  *	registered.
@@ -58,6 +72,15 @@ 
  *	cpufreq frequencies.
  * @allowed_cpus: all the cpus involved for this cpufreq_cooling_device.
  * @node: list_head to link all cpufreq_cooling_device together.
+ * @last_load: load measured by the latest call to cpufreq_get_actual_power()
+ * @time_in_idle: previous reading of the absolute time that this cpu was idle
+ * @time_in_idle_timestamp: wall time of the last invocation of
+ *	get_cpu_idle_time_us()
+ * @dyn_power_table: array of struct power_table for frequency to power
+ *	conversion, sorted in ascending order.
+ * @dyn_power_table_entries: number of entries in the @dyn_power_table array
+ * @cpu_dev: the first cpu_device from @allowed_cpus that has OPPs registered
+ * @plat_get_static_power: callback to calculate the static power
  *
  * This structure is required for keeping information of each registered
  * cpufreq_cooling_device.
@@ -71,6 +94,13 @@  struct cpufreq_cooling_device {
 	unsigned int *freq_table;	/* In descending order */
 	struct cpumask allowed_cpus;
 	struct list_head node;
+	u32 last_load;
+	u64 *time_in_idle;
+	u64 *time_in_idle_timestamp;
+	struct power_table *dyn_power_table;
+	int dyn_power_table_entries;
+	struct device *cpu_dev;
+	get_static_t plat_get_static_power;
 };
 static DEFINE_IDR(cpufreq_idr);
 static DEFINE_MUTEX(cooling_cpufreq_lock);
@@ -167,6 +197,39 @@  unsigned long cpufreq_cooling_get_level(unsigned int cpu, unsigned int freq)
 }
 EXPORT_SYMBOL_GPL(cpufreq_cooling_get_level);
 
+static void update_cpu_device(int cpu)
+{
+	struct cpufreq_cooling_device *cpufreq_dev;
+
+	mutex_lock(&cooling_cpufreq_lock);
+	list_for_each_entry(cpufreq_dev, &cpufreq_dev_list, node) {
+		if (cpumask_test_cpu(cpu, &cpufreq_dev->allowed_cpus)) {
+			cpufreq_dev->cpu_dev = get_cpu_device(cpu);
+			if (!cpufreq_dev->cpu_dev) {
+				dev_warn(&cpufreq_dev->cool_dev->device,
+					"No cpu device for new policy cpu %d\n",
+					 cpu);
+			}
+			break;
+		}
+	}
+	mutex_unlock(&cooling_cpufreq_lock);
+}
+
+static void remove_cpu_device(int cpu)
+{
+	struct cpufreq_cooling_device *cpufreq_dev;
+
+	mutex_lock(&cooling_cpufreq_lock);
+	list_for_each_entry(cpufreq_dev, &cpufreq_dev_list, node) {
+		if (cpumask_test_cpu(cpu, &cpufreq_dev->allowed_cpus)) {
+			cpufreq_dev->cpu_dev = NULL;
+			break;
+		}
+	}
+	mutex_unlock(&cooling_cpufreq_lock);
+}
+
 /**
  * cpufreq_thermal_notifier - notifier callback for cpufreq policy change.
  * @nb:	struct notifier_block * with callback info.
@@ -186,23 +249,240 @@  static int cpufreq_thermal_notifier(struct notifier_block *nb,
 	unsigned long max_freq = 0;
 	struct cpufreq_cooling_device *cpufreq_dev;
 
-	if (event != CPUFREQ_ADJUST)
-		return 0;
+	switch (event) {
 
-	mutex_lock(&cooling_cpufreq_lock);
-	list_for_each_entry(cpufreq_dev, &cpufreq_dev_list, node) {
-		if (!cpumask_test_cpu(policy->cpu,
-					&cpufreq_dev->allowed_cpus))
+	case CPUFREQ_ADJUST:
+		mutex_lock(&cooling_cpufreq_lock);
+		list_for_each_entry(cpufreq_dev, &cpufreq_dev_list, node) {
+			if (!cpumask_test_cpu(policy->cpu,
+					      &cpufreq_dev->allowed_cpus))
+				continue;
+
+			max_freq = cpufreq_dev->cpufreq_val;
+
+			if (policy->max != max_freq)
+				cpufreq_verify_within_limits(policy, 0,
+							     max_freq);
+		}
+		mutex_unlock(&cooling_cpufreq_lock);
+		break;
+
+	case CPUFREQ_CREATE_POLICY:
+		update_cpu_device(policy->cpu);
+		break;
+	case CPUFREQ_REMOVE_POLICY:
+		remove_cpu_device(policy->cpu);
+		break;
+	default:
+		return NOTIFY_DONE;
+	}
+
+	return NOTIFY_OK;
+}
+
+/**
+ * build_dyn_power_table() - create a dynamic power to frequency table
+ * @cpufreq_device:	the cpufreq cooling device in which to store the table
+ * @capacitance: dynamic power coefficient for these cpus
+ *
+ * Build a dynamic power to frequency table for this cpu and store it
+ * in @cpufreq_device.  This table will be used in cpu_power_to_freq() and
+ * cpu_freq_to_power() to convert between power and frequency
+ * efficiently.  Power is stored in mW, frequency in KHz.  The
+ * resulting table is in ascending order.
+ *
+ * Return: 0 on success, -E* on error.
+ */
+static int build_dyn_power_table(struct cpufreq_cooling_device *cpufreq_device,
+				 u32 capacitance)
+{
+	struct power_table *power_table;
+	struct dev_pm_opp *opp;
+	struct device *dev = NULL;
+	int num_opps = 0, cpu, i, ret = 0;
+	unsigned long freq;
+
+	rcu_read_lock();
+
+	for_each_cpu(cpu, &cpufreq_device->allowed_cpus) {
+		dev = get_cpu_device(cpu);
+		if (!dev) {
+			dev_warn(&cpufreq_device->cool_dev->device,
+				 "No cpu device for cpu %d\n", cpu);
 			continue;
+		}
 
-		max_freq = cpufreq_dev->cpufreq_val;
+		num_opps = dev_pm_opp_get_opp_count(dev);
+		if (num_opps > 0) {
+			break;
+		} else if (num_opps < 0) {
+			ret = num_opps;
+			goto unlock;
+		}
+	}
 
-		if (policy->max != max_freq)
-			cpufreq_verify_within_limits(policy, 0, max_freq);
+	if (num_opps == 0) {
+		ret = -EINVAL;
+		goto unlock;
 	}
-	mutex_unlock(&cooling_cpufreq_lock);
 
-	return 0;
+	power_table = kcalloc(num_opps, sizeof(*power_table), GFP_KERNEL);
+
+	for (freq = 0, i = 0;
+	     opp = dev_pm_opp_find_freq_ceil(dev, &freq), !IS_ERR(opp);
+	     freq++, i++) {
+		u32 freq_mhz, voltage_mv;
+		u64 power;
+
+		freq_mhz = freq / 1000000;
+		voltage_mv = dev_pm_opp_get_voltage(opp) / 1000;
+
+		/*
+		 * Do the multiplication with MHz and millivolt so as
+		 * to not overflow.
+		 */
+		power = (u64)capacitance * freq_mhz * voltage_mv * voltage_mv;
+		do_div(power, 1000000000);
+
+		/* frequency is stored in power_table in KHz */
+		power_table[i].frequency = freq / 1000;
+
+		/* power is stored in mW */
+		power_table[i].power = power;
+	}
+
+	if (i == 0) {
+		ret = PTR_ERR(opp);
+		goto unlock;
+	}
+
+	cpufreq_device->cpu_dev = dev;
+	cpufreq_device->dyn_power_table = power_table;
+	cpufreq_device->dyn_power_table_entries = i;
+
+unlock:
+	rcu_read_unlock();
+	return ret;
+}
+
+static u32 cpu_freq_to_power(struct cpufreq_cooling_device *cpufreq_device,
+			     u32 freq)
+{
+	int i;
+	struct power_table *pt = cpufreq_device->dyn_power_table;
+
+	for (i = 1; i < cpufreq_device->dyn_power_table_entries; i++)
+		if (freq < pt[i].frequency)
+			break;
+
+	return pt[i - 1].power;
+}
+
+static u32 cpu_power_to_freq(struct cpufreq_cooling_device *cpufreq_device,
+			     u32 power)
+{
+	int i;
+	struct power_table *pt = cpufreq_device->dyn_power_table;
+
+	for (i = 1; i < cpufreq_device->dyn_power_table_entries; i++)
+		if (power < pt[i].power)
+			break;
+
+	return pt[i - 1].frequency;
+}
+
+/**
+ * get_load() - get load for a cpu since last updated
+ * @cpufreq_device:	&struct cpufreq_cooling_device for this cpu
+ * @cpu:	cpu number
+ *
+ * Return: The average load of cpu @cpu in percentage since this
+ * function was last called.
+ */
+static u32 get_load(struct cpufreq_cooling_device *cpufreq_device, int cpu)
+{
+	u32 load;
+	u64 now, now_idle, delta_time, delta_idle;
+
+	now_idle = get_cpu_idle_time(cpu, &now, 0);
+	delta_idle = now_idle - cpufreq_device->time_in_idle[cpu];
+	delta_time = now - cpufreq_device->time_in_idle_timestamp[cpu];
+
+	if (delta_time <= delta_idle)
+		load = 0;
+	else
+		load = div64_u64(100 * (delta_time - delta_idle), delta_time);
+
+	cpufreq_device->time_in_idle[cpu] = now_idle;
+	cpufreq_device->time_in_idle_timestamp[cpu] = now;
+
+	return load;
+}
+
+/**
+ * get_static_power() - calculate the static power consumed by the cpus
+ * @cpufreq_device:	struct &cpufreq_cooling_device for this cpu cdev
+ * @tz:		thermal zone device in which we're operating
+ * @freq:	frequency in KHz
+ * @power:	pointer in which to store the calculated static power
+ *
+ * Calculate the static power consumed by the cpus described by
+ * @cpu_actor running at frequency @freq.  This function relies on a
+ * platform specific function that should have been provided when the
+ * actor was registered.  If it wasn't, the static power is assumed to
+ * be negligible.  The calculated static power is stored in @power.
+ *
+ * Return: 0 on success, -E* on failure.
+ */
+static int get_static_power(struct cpufreq_cooling_device *cpufreq_device,
+			    struct thermal_zone_device *tz, unsigned long freq,
+			    u32 *power)
+{
+	struct dev_pm_opp *opp;
+	unsigned long voltage;
+	struct cpumask *cpumask = &cpufreq_device->allowed_cpus;
+	unsigned long freq_hz = freq * 1000;
+
+	if (!cpufreq_device->plat_get_static_power ||
+	    !cpufreq_device->cpu_dev) {
+		*power = 0;
+		return 0;
+	}
+
+	rcu_read_lock();
+
+	opp = dev_pm_opp_find_freq_exact(cpufreq_device->cpu_dev, freq_hz,
+					 true);
+	voltage = dev_pm_opp_get_voltage(opp);
+
+	rcu_read_unlock();
+
+	if (voltage == 0) {
+		dev_warn_ratelimited(cpufreq_device->cpu_dev,
+				     "Failed to get voltage for frequency %lu: %ld\n",
+				     freq_hz, IS_ERR(opp) ? PTR_ERR(opp) : 0);
+		return -EINVAL;
+	}
+
+	return cpufreq_device->plat_get_static_power(cpumask, tz->passive_delay,
+						     voltage, power);
+}
+
+/**
+ * get_dynamic_power() - calculate the dynamic power
+ * @cpufreq_device:	&cpufreq_cooling_device for this cdev
+ * @freq:	current frequency
+ *
+ * Return: the dynamic power consumed by the cpus described by
+ * @cpufreq_device.
+ */
+static u32 get_dynamic_power(struct cpufreq_cooling_device *cpufreq_device,
+			     unsigned long freq)
+{
+	u32 raw_cpu_power;
+
+	raw_cpu_power = cpu_freq_to_power(cpufreq_device, freq);
+	return (raw_cpu_power * cpufreq_device->last_load) / 100;
 }
 
 /* cpufreq cooling device callback functions are defined below */
@@ -280,8 +560,169 @@  static int cpufreq_set_cur_state(struct thermal_cooling_device *cdev,
 	return 0;
 }
 
+/**
+ * cpufreq_get_requested_power() - get the current power
+ * @cdev:	&thermal_cooling_device pointer
+ * @tz:		a valid thermal zone device pointer
+ * @power:	pointer in which to store the resulting power
+ *
+ * Calculate the current power consumption of the cpus in milliwatts
+ * and store it in @power.  This function should actually calculate
+ * the requested power, but it's hard to get the frequency that
+ * cpufreq would have assigned if there were no thermal limits.
+ * Instead, we calculate the current power on the assumption that the
+ * immediate future will look like the immediate past.
+ *
+ * We use the current frequency and the average load since this
+ * function was last called.  In reality, there could have been
+ * multiple opps since this function was last called and that affects
+ * the load calculation.  While it's not perfectly accurate, this
+ * simplification is good enough and works.  REVISIT this, as more
+ * complex code may be needed if experiments show that it's not
+ * accurate enough.
+ *
+ * Return: 0 on success, -E* if getting the static power failed.
+ */
+static int cpufreq_get_requested_power(struct thermal_cooling_device *cdev,
+				       struct thermal_zone_device *tz,
+				       u32 *power)
+{
+	unsigned long freq;
+	int cpu, ret;
+	u32 static_power, dynamic_power, total_load = 0;
+	struct cpufreq_cooling_device *cpufreq_device = cdev->devdata;
+
+	freq = cpufreq_quick_get(cpumask_any(&cpufreq_device->allowed_cpus));
+
+	for_each_cpu(cpu, &cpufreq_device->allowed_cpus) {
+		u32 load;
+
+		if (cpu_online(cpu))
+			load = get_load(cpufreq_device, cpu);
+		else
+			load = 0;
+
+		total_load += load;
+	}
+
+	cpufreq_device->last_load = total_load;
+
+	dynamic_power = get_dynamic_power(cpufreq_device, freq);
+	ret = get_static_power(cpufreq_device, tz, freq, &static_power);
+	if (ret)
+		return ret;
+
+	*power = static_power + dynamic_power;
+	return 0;
+}
+
+/**
+ * cpufreq_state2power() - convert a cpu cdev state to power consumed
+ * @cdev:	&thermal_cooling_device pointer
+ * @tz:		a valid thermal zone device pointer
+ * @state:	cooling device state to be converted
+ * @power:	pointer in which to store the resulting power
+ *
+ * Convert cooling device state @state into power consumption in
+ * milliwatts assuming 100% load.  Store the calculated power in
+ * @power.
+ *
+ * Return: 0 on success, -EINVAL if the cooling device state could not
+ * be converted into a frequency or other -E* if there was an error
+ * when calculating the static power.
+ */
+static int cpufreq_state2power(struct thermal_cooling_device *cdev,
+			       struct thermal_zone_device *tz,
+			       unsigned long state, u32 *power)
+{
+	unsigned int freq, num_cpus;
+	cpumask_t cpumask;
+	u32 static_power, dynamic_power;
+	int ret;
+	struct cpufreq_cooling_device *cpufreq_device = cdev->devdata;
+
+	cpumask_and(&cpumask, &cpufreq_device->allowed_cpus, cpu_online_mask);
+	num_cpus = cpumask_weight(&cpumask);
+
+	/* None of our cpus are online, so no power */
+	if (num_cpus == 0) {
+		*power = 0;
+		return 0;
+	}
+
+	freq = cpufreq_device->freq_table[state];
+	if (!freq)
+		return -EINVAL;
+
+	dynamic_power = cpu_freq_to_power(cpufreq_device, freq) * num_cpus;
+	ret = get_static_power(cpufreq_device, tz, freq, &static_power);
+	if (ret)
+		return ret;
+
+	*power = static_power + dynamic_power;
+	return 0;
+}
+
+/**
+ * cpufreq_power2state() - convert power to a cooling device state
+ * @cdev:	&thermal_cooling_device pointer
+ * @tz:		a valid thermal zone device pointer
+ * @power:	power in milliwatts to be converted
+ * @state:	pointer in which to store the resulting state
+ *
+ * Calculate a cooling device state for the cpus described by @cdev
+ * that would allow them to consume at most @power mW and store it in
+ * @state.  Note that this calculation depends on external factors
+ * such as the cpu load or the current static power.  Calling this
+ * function with the same power as input can yield different cooling
+ * device states depending on those external factors.
+ *
+ * Return: 0 on success, -ENODEV if no cpus are online or -EINVAL if
+ * the calculated frequency could not be converted to a valid state.
+ * The latter should not happen unless the frequencies available to
+ * cpufreq have changed since the initialization of the cpu cooling
+ * device.
+ */
+static int cpufreq_power2state(struct thermal_cooling_device *cdev,
+			       struct thermal_zone_device *tz, u32 power,
+			       unsigned long *state)
+{
+	unsigned int cpu, cur_freq, target_freq;
+	int ret;
+	s32 dyn_power;
+	u32 last_load, normalised_power, static_power;
+	struct cpufreq_cooling_device *cpufreq_device = cdev->devdata;
+
+	cpu = cpumask_any_and(&cpufreq_device->allowed_cpus, cpu_online_mask);
+
+	/* None of our cpus are online */
+	if (cpu >= nr_cpu_ids)
+		return -ENODEV;
+
+	cur_freq = cpufreq_quick_get(cpu);
+	ret = get_static_power(cpufreq_device, tz, cur_freq, &static_power);
+	if (ret)
+		return ret;
+
+	dyn_power = power - static_power;
+	dyn_power = dyn_power > 0 ? dyn_power : 0;
+	last_load = cpufreq_device->last_load ?: 1;
+	normalised_power = (dyn_power * 100) / last_load;
+	target_freq = cpu_power_to_freq(cpufreq_device, normalised_power);
+
+	*state = cpufreq_cooling_get_level(cpu, target_freq);
+	if (*state == THERMAL_CSTATE_INVALID) {
+		dev_warn_ratelimited(&cdev->device,
+				     "Failed to convert %dKHz for cpu %d into a cdev state\n",
+				     target_freq, cpu);
+		return -EINVAL;
+	}
+
+	return 0;
+}
+
 /* Bind cpufreq callbacks to thermal cooling device ops */
-static struct thermal_cooling_device_ops const cpufreq_cooling_ops = {
+static struct thermal_cooling_device_ops cpufreq_cooling_ops = {
 	.get_max_state = cpufreq_get_max_state,
 	.get_cur_state = cpufreq_get_cur_state,
 	.set_cur_state = cpufreq_set_cur_state,
@@ -311,6 +752,9 @@  static unsigned int find_next_max(struct cpufreq_frequency_table *table,
  * @np: a valid struct device_node to the cooling device device tree node
  * @clip_cpus: cpumask of cpus where the frequency constraints will happen.
  * Normally this should be same as cpufreq policy->related_cpus.
+ * @capacitance: dynamic power coefficient for these cpus
+ * @plat_static_func: function to calculate the static power consumed by these
+ *                    cpus (optional)
  *
  * This interface function registers the cpufreq cooling device with the name
  * "thermal-cpufreq-%x". This api can support multiple instances of cpufreq
@@ -322,13 +766,14 @@  static unsigned int find_next_max(struct cpufreq_frequency_table *table,
  */
 static struct thermal_cooling_device *
 __cpufreq_cooling_register(struct device_node *np,
-			   const struct cpumask *clip_cpus)
+			const struct cpumask *clip_cpus, u32 capacitance,
+			get_static_t plat_static_func)
 {
 	struct thermal_cooling_device *cool_dev;
 	struct cpufreq_cooling_device *cpufreq_dev;
 	char dev_name[THERMAL_NAME_LENGTH];
 	struct cpufreq_frequency_table *pos, *table;
-	unsigned int freq, i;
+	unsigned int freq, i, num_cpus;
 	int ret;
 
 	table = cpufreq_frequency_get_table(cpumask_first(clip_cpus));
@@ -341,6 +786,23 @@  __cpufreq_cooling_register(struct device_node *np,
 	if (!cpufreq_dev)
 		return ERR_PTR(-ENOMEM);
 
+	num_cpus = cpumask_weight(clip_cpus);
+	cpufreq_dev->time_in_idle = kcalloc(num_cpus,
+					    sizeof(*cpufreq_dev->time_in_idle),
+					    GFP_KERNEL);
+	if (!cpufreq_dev->time_in_idle) {
+		cool_dev = ERR_PTR(-ENOMEM);
+		goto free_cdev;
+	}
+
+	cpufreq_dev->time_in_idle_timestamp =
+		kcalloc(num_cpus, sizeof(*cpufreq_dev->time_in_idle_timestamp),
+			GFP_KERNEL);
+	if (!cpufreq_dev->time_in_idle_timestamp) {
+		cool_dev = ERR_PTR(-ENOMEM);
+		goto free_time_in_idle;
+	}
+
 	/* Find max levels */
 	cpufreq_for_each_valid_entry(pos, table)
 		cpufreq_dev->max_level++;
@@ -349,7 +811,7 @@  __cpufreq_cooling_register(struct device_node *np,
 					  cpufreq_dev->max_level, GFP_KERNEL);
 	if (!cpufreq_dev->freq_table) {
 		cool_dev = ERR_PTR(-ENOMEM);
-		goto free_cdev;
+		goto free_time_in_idle_timestamp;
 	}
 
 	/* max_level is an index, not a counter */
@@ -357,6 +819,20 @@  __cpufreq_cooling_register(struct device_node *np,
 
 	cpumask_copy(&cpufreq_dev->allowed_cpus, clip_cpus);
 
+	if (capacitance) {
+		cpufreq_cooling_ops.get_requested_power =
+			cpufreq_get_requested_power;
+		cpufreq_cooling_ops.state2power = cpufreq_state2power;
+		cpufreq_cooling_ops.power2state = cpufreq_power2state;
+		cpufreq_dev->plat_get_static_power = plat_static_func;
+
+		ret = build_dyn_power_table(cpufreq_dev, capacitance);
+		if (ret) {
+			cool_dev = ERR_PTR(ret);
+			goto free_table;
+		}
+	}
+
 	ret = get_idr(&cpufreq_idr, &cpufreq_dev->id);
 	if (ret) {
 		cool_dev = ERR_PTR(ret);
@@ -402,6 +878,10 @@  remove_idr:
 	release_idr(&cpufreq_idr, cpufreq_dev->id);
 free_table:
 	kfree(cpufreq_dev->freq_table);
+free_time_in_idle_timestamp:
+	kfree(cpufreq_dev->time_in_idle_timestamp);
+free_time_in_idle:
+	kfree(cpufreq_dev->time_in_idle);
 free_cdev:
 	kfree(cpufreq_dev);
 
@@ -422,7 +902,7 @@  free_cdev:
 struct thermal_cooling_device *
 cpufreq_cooling_register(const struct cpumask *clip_cpus)
 {
-	return __cpufreq_cooling_register(NULL, clip_cpus);
+	return __cpufreq_cooling_register(NULL, clip_cpus, 0, NULL);
 }
 EXPORT_SYMBOL_GPL(cpufreq_cooling_register);
 
@@ -446,11 +926,78 @@  of_cpufreq_cooling_register(struct device_node *np,
 	if (!np)
 		return ERR_PTR(-EINVAL);
 
-	return __cpufreq_cooling_register(np, clip_cpus);
+	return __cpufreq_cooling_register(np, clip_cpus, 0, NULL);
 }
 EXPORT_SYMBOL_GPL(of_cpufreq_cooling_register);
 
 /**
+ * cpufreq_power_cooling_register() - create cpufreq cooling device with power extensions
+ * @clip_cpus:	cpumask of cpus where the frequency constraints will happen
+ * @capacitance:	dynamic power coefficient for these cpus
+ * @plat_static_func:	function to calculate the static power consumed by these
+ *			cpus (optional)
+ *
+ * This interface function registers the cpufreq cooling device with
+ * the name "thermal-cpufreq-%x".  This api can support multiple
+ * instances of cpufreq cooling devices.  Using this function, the
+ * cooling device will implement the power extensions by using a
+ * simple cpu power model.  The cpus must have registered their OPPs
+ * using the OPP library.
+ *
+ * An optional @plat_static_func may be provided to calculate the
+ * static power consumed by these cpus.  If the platform's static
+ * power consumption is unknown or negligible, make it NULL.
+ *
+ * Return: a valid struct thermal_cooling_device pointer on success,
+ * on failure, it returns a corresponding ERR_PTR().
+ */
+struct thermal_cooling_device *
+cpufreq_power_cooling_register(const struct cpumask *clip_cpus, u32 capacitance,
+			       get_static_t plat_static_func)
+{
+	return __cpufreq_cooling_register(NULL, clip_cpus, capacitance,
+				plat_static_func);
+}
+EXPORT_SYMBOL(cpufreq_power_cooling_register);
+
+/**
+ * of_cpufreq_power_cooling_register() - create cpufreq cooling device with power extensions
+ * @np:	a valid struct device_node to the cooling device device tree node
+ * @clip_cpus:	cpumask of cpus where the frequency constraints will happen
+ * @capacitance:	dynamic power coefficient for these cpus
+ * @plat_static_func:	function to calculate the static power consumed by these
+ *			cpus (optional)
+ *
+ * This interface function registers the cpufreq cooling device with
+ * the name "thermal-cpufreq-%x".  This api can support multiple
+ * instances of cpufreq cooling devices.  Using this API, the cpufreq
+ * cooling device will be linked to the device tree node provided.
+ * Using this function, the cooling device will implement the power
+ * extensions by using a simple cpu power model.  The cpus must have
+ * registered their OPPs using the OPP library.
+ *
+ * An optional @plat_static_func may be provided to calculate the
+ * static power consumed by these cpus.  If the platform's static
+ * power consumption is unknown or negligible, make it NULL.
+ *
+ * Return: a valid struct thermal_cooling_device pointer on success,
+ * on failure, it returns a corresponding ERR_PTR().
+ */
+struct thermal_cooling_device *
+of_cpufreq_power_cooling_register(struct device_node *np,
+				  const struct cpumask *clip_cpus,
+				  u32 capacitance,
+				  get_static_t plat_static_func)
+{
+	if (!np)
+		return ERR_PTR(-EINVAL);
+
+	return __cpufreq_cooling_register(np, clip_cpus, capacitance,
+				plat_static_func);
+}
+EXPORT_SYMBOL(of_cpufreq_power_cooling_register);
+
+/**
  * cpufreq_cooling_unregister - function to remove cpufreq cooling device.
  * @cdev: thermal cooling device pointer.
  *
@@ -475,6 +1022,8 @@  void cpufreq_cooling_unregister(struct thermal_cooling_device *cdev)
 
 	thermal_cooling_device_unregister(cpufreq_dev->cool_dev);
 	release_idr(&cpufreq_idr, cpufreq_dev->id);
+	kfree(cpufreq_dev->time_in_idle_timestamp);
+	kfree(cpufreq_dev->time_in_idle);
 	kfree(cpufreq_dev->freq_table);
 	kfree(cpufreq_dev);
 }
diff --git a/include/linux/cpu_cooling.h b/include/linux/cpu_cooling.h
index bd955270d5aa..c156f5082758 100644
--- a/include/linux/cpu_cooling.h
+++ b/include/linux/cpu_cooling.h
@@ -28,6 +28,9 @@ 
 #include <linux/thermal.h>
 #include <linux/cpumask.h>
 
+typedef int (*get_static_t)(cpumask_t *cpumask, int interval,
+			    unsigned long voltage, u32 *power);
+
 #ifdef CONFIG_CPU_THERMAL
 /**
  * cpufreq_cooling_register - function to create cpufreq cooling device.
@@ -36,6 +39,10 @@ 
 struct thermal_cooling_device *
 cpufreq_cooling_register(const struct cpumask *clip_cpus);
 
+struct thermal_cooling_device *
+cpufreq_power_cooling_register(const struct cpumask *clip_cpus,
+			       u32 capacitance, get_static_t plat_static_func);
+
 /**
  * of_cpufreq_cooling_register - create cpufreq cooling device based on DT.
  * @np: a valid struct device_node to the cooling device device tree node.
@@ -45,6 +52,12 @@  cpufreq_cooling_register(const struct cpumask *clip_cpus);
 struct thermal_cooling_device *
 of_cpufreq_cooling_register(struct device_node *np,
 			    const struct cpumask *clip_cpus);
+
+struct thermal_cooling_device *
+of_cpufreq_power_cooling_register(struct device_node *np,
+				  const struct cpumask *clip_cpus,
+				  u32 capacitance,
+				  get_static_t plat_static_func);
 #else
 static inline struct thermal_cooling_device *
 of_cpufreq_cooling_register(struct device_node *np,
@@ -52,6 +65,15 @@  of_cpufreq_cooling_register(struct device_node *np,
 {
 	return ERR_PTR(-ENOSYS);
 }
+
+static inline struct thermal_cooling_device *
+of_cpufreq_power_cooling_register(struct device_node *np,
+				  const struct cpumask *clip_cpus,
+				  u32 capacitance,
+				  get_static_t plat_static_func)
+{
+	return NULL;
+}
 #endif
 
 /**
@@ -68,11 +90,28 @@  cpufreq_cooling_register(const struct cpumask *clip_cpus)
 	return ERR_PTR(-ENOSYS);
 }
 static inline struct thermal_cooling_device *
+cpufreq_power_cooling_register(const struct cpumask *clip_cpus,
+			       u32 capacitance, get_static_t plat_static_func)
+{
+	return NULL;
+}
+
+static inline struct thermal_cooling_device *
 of_cpufreq_cooling_register(struct device_node *np,
 			    const struct cpumask *clip_cpus)
 {
 	return ERR_PTR(-ENOSYS);
 }
+
+static inline struct thermal_cooling_device *
+of_cpufreq_power_cooling_register(struct device_node *np,
+				  const struct cpumask *clip_cpus,
+				  u32 capacitance,
+				  get_static_t plat_static_func)
+{
+	return NULL;
+}
+
 static inline
 void cpufreq_cooling_unregister(struct thermal_cooling_device *cdev)
 {