OPP: refactor dev_pm_opp_of_register_em() and update related drivers

The Energy Model framework supports not only CPU devices. Drop the CPU
specific interface with cpumask and add struct device. Add also a return
value, user might use it. This new interface provides easy way to create
a simple Energy Model, which then might be used by e.g. thermal subsystem.

Acked-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Signed-off-by: Lukasz Luba <lukasz.luba@arm.com>
Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@intel.com>

drivers/cpufreq/cpufreq-dt.c

@@ -279,7 +279,7 @@ static int cpufreq_init(struct cpufreq_policy *policy)
 	policy->cpuinfo.transition_latency = transition_latency;
 	policy->dvfs_possible_from_any_cpu = true;
 
-	dev_pm_opp_of_register_em(policy->cpus);
+	dev_pm_opp_of_register_em(cpu_dev, policy->cpus);
 
 	return 0;
 

drivers/cpufreq/imx6q-cpufreq.c

@@ -193,7 +193,7 @@ static int imx6q_cpufreq_init(struct cpufreq_policy *policy)
 	policy->clk = clks[ARM].clk;
 	cpufreq_generic_init(policy, freq_table, transition_latency);
 	policy->suspend_freq = max_freq;
-	dev_pm_opp_of_register_em(policy->cpus);
+	dev_pm_opp_of_register_em(cpu_dev, policy->cpus);
 
 	return 0;
 }

drivers/cpufreq/mediatek-cpufreq.c

@@ -448,7 +448,7 @@ static int mtk_cpufreq_init(struct cpufreq_policy *policy)
 	policy->driver_data = info;
 	policy->clk = info->cpu_clk;
 
-	dev_pm_opp_of_register_em(policy->cpus);
+	dev_pm_opp_of_register_em(info->cpu_dev, policy->cpus);
 
 	return 0;
 }

drivers/cpufreq/omap-cpufreq.c

@@ -131,7 +131,7 @@ static int omap_cpu_init(struct cpufreq_policy *policy)
 
 	/* FIXME: what's the actual transition time? */
 	cpufreq_generic_init(policy, freq_table, 300 * 1000);
-	dev_pm_opp_of_register_em(policy->cpus);
+	dev_pm_opp_of_register_em(mpu_dev, policy->cpus);
 
 	return 0;
 }

drivers/cpufreq/qcom-cpufreq-hw.c

@@ -238,7 +238,7 @@ static int qcom_cpufreq_hw_cpu_init(struct cpufreq_policy *policy)
 		goto error;
 	}
 
-	dev_pm_opp_of_register_em(policy->cpus);
+	dev_pm_opp_of_register_em(cpu_dev, policy->cpus);
 
 	policy->fast_switch_possible = true;
 

drivers/cpufreq/scpi-cpufreq.c

@@ -167,7 +167,7 @@ static int scpi_cpufreq_init(struct cpufreq_policy *policy)
 
 	policy->fast_switch_possible = false;
 
-	dev_pm_opp_of_register_em(policy->cpus);
+	dev_pm_opp_of_register_em(cpu_dev, policy->cpus);
 
 	return 0;
 

drivers/cpufreq/vexpress-spc-cpufreq.c

@@ -450,7 +450,7 @@ static int ve_spc_cpufreq_init(struct cpufreq_policy *policy)
 	policy->freq_table = freq_table[cur_cluster];
 	policy->cpuinfo.transition_latency = 1000000; /* 1 ms */
 
-	dev_pm_opp_of_register_em(policy->cpus);
+	dev_pm_opp_of_register_em(cpu_dev, policy->cpus);
 
 	if (is_bL_switching_enabled())
 		per_cpu(cpu_last_req_freq, policy->cpu) =

drivers/opp/of.c

@@ -1205,18 +1205,18 @@ EXPORT_SYMBOL_GPL(dev_pm_opp_get_of_node);
 
 /*
  * Callback function provided to the Energy Model framework upon registration.
- * This computes the power estimated by @CPU at @kHz if it is the frequency
+ * This computes the power estimated by @dev at @kHz if it is the frequency
  * of an existing OPP, or at the frequency of the first OPP above @kHz otherwise
  * (see dev_pm_opp_find_freq_ceil()). This function updates @kHz to the ceiled
  * frequency and @mW to the associated power. The power is estimated as
- * P = C * V^2 * f with C being the CPU's capacitance and V and f respectively
- * the voltage and frequency of the OPP.
+ * P = C * V^2 * f with C being the device's capacitance and V and f
+ * respectively the voltage and frequency of the OPP.
  *
- * Returns -ENODEV if the CPU device cannot be found, -EINVAL if the power
- * calculation failed because of missing parameters, 0 otherwise.
+ * Returns -EINVAL if the power calculation failed because of missing
+ * parameters, 0 otherwise.
  */
-static int __maybe_unused _get_cpu_power(unsigned long *mW, unsigned long *kHz,
-					 struct device *cpu_dev)
+static int __maybe_unused _get_power(unsigned long *mW, unsigned long *kHz,
+				     struct device *dev)
 {
 	struct dev_pm_opp *opp;
 	struct device_node *np;
@@ -1225,7 +1225,7 @@ static int __maybe_unused _get_cpu_power(unsigned long *mW, unsigned long *kHz,
 	u64 tmp;
 	int ret;
 
-	np = of_node_get(cpu_dev->of_node);
+	np = of_node_get(dev->of_node);
 	if (!np)
 		return -EINVAL;
 
@@ -1235,7 +1235,7 @@ static int __maybe_unused _get_cpu_power(unsigned long *mW, unsigned long *kHz,
 		return -EINVAL;
 
 	Hz = *kHz * 1000;
-	opp = dev_pm_opp_find_freq_ceil(cpu_dev, &Hz);
+	opp = dev_pm_opp_find_freq_ceil(dev, &Hz);
 	if (IS_ERR(opp))
 		return -EINVAL;
 
@@ -1255,30 +1255,38 @@ static int __maybe_unused _get_cpu_power(unsigned long *mW, unsigned long *kHz,
 
 /**
  * dev_pm_opp_of_register_em() - Attempt to register an Energy Model
- * @cpus	: CPUs for which an Energy Model has to be registered
+ * @dev		: Device for which an Energy Model has to be registered
+ * @cpus	: CPUs for which an Energy Model has to be registered. For
+ *		other type of devices it should be set to NULL.
  *
  * This checks whether the "dynamic-power-coefficient" devicetree property has
  * been specified, and tries to register an Energy Model with it if it has.
+ * Having this property means the voltages are known for OPPs and the EM
+ * might be calculated.
  */
-void dev_pm_opp_of_register_em(struct cpumask *cpus)
+int dev_pm_opp_of_register_em(struct device *dev, struct cpumask *cpus)
 {
-	struct em_data_callback em_cb = EM_DATA_CB(_get_cpu_power);
-	int ret, nr_opp, cpu = cpumask_first(cpus);
-	struct device *cpu_dev;
+	struct em_data_callback em_cb = EM_DATA_CB(_get_power);
 	struct device_node *np;
+	int ret, nr_opp;
 	u32 cap;
 
-	cpu_dev = get_cpu_device(cpu);
-	if (!cpu_dev)
-		return;
+	if (IS_ERR_OR_NULL(dev)) {
+		ret = -EINVAL;
+		goto failed;
+	}
 
-	nr_opp = dev_pm_opp_get_opp_count(cpu_dev);
-	if (nr_opp <= 0)
-		return;
+	nr_opp = dev_pm_opp_get_opp_count(dev);
+	if (nr_opp <= 0) {
+		ret = -EINVAL;
+		goto failed;
+	}
 
-	np = of_node_get(cpu_dev->of_node);
-	if (!np)
-		return;
+	np = of_node_get(dev->of_node);
+	if (!np) {
+		ret = -EINVAL;
+		goto failed;
+	}
 
 	/*
 	 * Register an EM only if the 'dynamic-power-coefficient' property is
@@ -1289,9 +1297,20 @@ void dev_pm_opp_of_register_em(struct cpumask *cpus)
 	 */
 	ret = of_property_read_u32(np, "dynamic-power-coefficient", &cap);
 	of_node_put(np);
-	if (ret || !cap)
-		return;
+	if (ret || !cap) {
+		dev_dbg(dev, "Couldn't find proper 'dynamic-power-coefficient' in DT\n");
+		ret = -EINVAL;
+		goto failed;
+	}
 
-	em_dev_register_perf_domain(cpu_dev, nr_opp, &em_cb, cpus);
+	ret = em_dev_register_perf_domain(dev, nr_opp, &em_cb, cpus);
+	if (ret)
+		goto failed;
+
+	return 0;
+
+failed:
+	dev_dbg(dev, "Couldn't register Energy Model %d\n", ret);
+	return ret;
 }
 EXPORT_SYMBOL_GPL(dev_pm_opp_of_register_em);

include/linux/pm_opp.h

@@ -11,6 +11,7 @@
 #ifndef __LINUX_OPP_H__
 #define __LINUX_OPP_H__
 
+#include <linux/energy_model.h>
 #include <linux/err.h>
 #include <linux/notifier.h>
 
@@ -373,7 +374,11 @@ struct device_node *dev_pm_opp_of_get_opp_desc_node(struct device *dev);
 struct device_node *dev_pm_opp_get_of_node(struct dev_pm_opp *opp);
 int of_get_required_opp_performance_state(struct device_node *np, int index);
 int dev_pm_opp_of_find_icc_paths(struct device *dev, struct opp_table *opp_table);
-void dev_pm_opp_of_register_em(struct cpumask *cpus);
+int dev_pm_opp_of_register_em(struct device *dev, struct cpumask *cpus);
+static inline void dev_pm_opp_of_unregister_em(struct device *dev)
+{
+	em_dev_unregister_perf_domain(dev);
+}
 #else
 static inline int dev_pm_opp_of_add_table(struct device *dev)
 {
@@ -413,7 +418,13 @@ static inline struct device_node *dev_pm_opp_get_of_node(struct dev_pm_opp *opp)
 	return NULL;
 }
 
-static inline void dev_pm_opp_of_register_em(struct cpumask *cpus)
+static inline int dev_pm_opp_of_register_em(struct device *dev,
+					    struct cpumask *cpus)
+{
+	return -ENOTSUPP;
+}
+
+static inline void dev_pm_opp_of_unregister_em(struct device *dev)
 {
 }