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Commit 23977789 authored by Quentin Perret's avatar Quentin Perret
Browse files

FROMLIST: cpufreq: dt: Register an Energy Model 

The Energy Model framework provides an API to register the active power
of CPUs. Call this API from the cpufreq-dt driver with an estimation
of the power as P = C * V^2 * f with C, V, and f respectively the
capacitance of the CPU and the voltage and frequency of the OPP.

The CPU capacitance is read from the "dynamic-power-coefficient" DT
binding (originally introduced for thermal/IPA), and the voltage and
frequency values from PM_OPP.

Change-Id: Id7b79ae3aafcc53574b850cb91a25240ebffbdd4
Cc: "Rafael J. Wysocki" <rjw@rjwysocki.net>
Cc: Viresh Kumar <viresh.kumar@linaro.org>
(Removed "OPTIONAL" label from title. Applied from
https://lore.kernel.org/lkml/20180912091309.7551-15-quentin.perret@arm.com/

)
Signed-off-by: default avatarQuentin Perret <quentin.perret@arm.com>
parent 6ed388bc

drivers/cpufreq/cpufreq-dt.c

+47 −1
Original line number Diff line number Diff line
@@ -16,6 +16,7 @@ 
#include <linux/cpu_cooling.h>

#include <linux/cpufreq.h>

#include <linux/cpumask.h>

#include <linux/energy_model.h>

#include <linux/err.h>

#include <linux/module.h>

#include <linux/of.h>
@@ -149,8 +150,50 @@ static int resources_available(void) 
	return 0;

}



static int __maybe_unused of_est_power(unsigned long *mW, unsigned long *KHz,

				       int cpu)

{

	unsigned long mV, Hz, MHz;

	struct device *cpu_dev;

	struct dev_pm_opp *opp;

	struct device_node *np;

	u32 cap;

	u64 tmp;



	cpu_dev = get_cpu_device(cpu);

	if (!cpu_dev)

		return -ENODEV;



	np = of_node_get(cpu_dev->of_node);

	if (!np)

		return -EINVAL;



	if (of_property_read_u32(np, "dynamic-power-coefficient", &cap))

		return -EINVAL;



	Hz = *KHz * 1000;

	opp = dev_pm_opp_find_freq_ceil(cpu_dev, &Hz);

	if (IS_ERR(opp))

		return -EINVAL;



	mV = dev_pm_opp_get_voltage(opp) / 1000;

	dev_pm_opp_put(opp);

	if (!mV)

		return -EINVAL;



	MHz = Hz / 1000000;

	tmp = (u64)cap * mV * mV * MHz;

	do_div(tmp, 1000000000);



	*mW = (unsigned long)tmp;

	*KHz = Hz / 1000;



	return 0;

}



static int cpufreq_init(struct cpufreq_policy *policy)

{

	struct em_data_callback em_cb = EM_DATA_CB(of_est_power);

	struct cpufreq_frequency_table *freq_table;

	struct opp_table *opp_table = NULL;

	struct private_data *priv;
@@ -159,7 +202,7 @@ static int cpufreq_init(struct cpufreq_policy *policy) 
	unsigned int transition_latency;

	bool fallback = false;

	const char *name;

	int ret;

	int ret, nr_opp;



	cpu_dev = get_cpu_device(policy->cpu);

	if (!cpu_dev) {
@@ -226,6 +269,7 @@ static int cpufreq_init(struct cpufreq_policy *policy) 
		ret = -EPROBE_DEFER;

		goto out_free_opp;

	}

	nr_opp = ret;



	if (fallback) {

		cpumask_setall(policy->cpus);
@@ -278,6 +322,8 @@ static int cpufreq_init(struct cpufreq_policy *policy) 
	policy->cpuinfo.transition_latency = transition_latency;

	policy->dvfs_possible_from_any_cpu = true;



	em_register_perf_domain(policy->cpus, nr_opp, &em_cb);



	return 0;



out_free_cpufreq_table: