thermal: devfreq_cooling: add new registration functions with Energy Model

The Energy Model (EM) framework supports devices such as Devfreq. Create
new registration function which automatically register EM for the thermal
devfreq_cooling devices. This patch prepares the code for coming changes
which are going to replace old power model with the new EM.
Reviewed-by: Ionela Voinescu <ionela.voinescu@arm.com>
Signed-off-by: Lukasz Luba <lukasz.luba@arm.com>
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Link: https://lore.kernel.org/r/20201210143014.24685-4-lukasz.luba@arm.com

drivers/thermal/devfreq_cooling.c

@@ -12,6 +12,7 @@
 
 #include <linux/devfreq.h>
 #include <linux/devfreq_cooling.h>
+#include <linux/energy_model.h>
 #include <linux/export.h>
 #include <linux/idr.h>
 #include <linux/slab.h>
@@ -576,22 +577,73 @@ struct thermal_cooling_device *devfreq_cooling_register(struct devfreq *df)
 }
 EXPORT_SYMBOL_GPL(devfreq_cooling_register);
 
+/**
+ * devfreq_cooling_em_register_power() - Register devfreq cooling device with
+ *		power information and automatically register Energy Model (EM)
+ * @df:		Pointer to devfreq device.
+ * @dfc_power:	Pointer to devfreq_cooling_power.
+ *
+ * Register a devfreq cooling device and automatically register EM. The
+ * available OPPs must be registered for the device.
+ *
+ * If @dfc_power is provided, the cooling device is registered with the
+ * power extensions. It is using the simple Energy Model which requires
+ * "dynamic-power-coefficient" a devicetree property. To not break drivers
+ * which miss that DT property, the function won't bail out when the EM
+ * registration failed. The cooling device will be registered if everything
+ * else is OK.
+ */
+struct thermal_cooling_device *
+devfreq_cooling_em_register(struct devfreq *df,
+			    struct devfreq_cooling_power *dfc_power)
+{
+	struct thermal_cooling_device *cdev;
+	struct device *dev;
+	int ret;
+
+	if (IS_ERR_OR_NULL(df))
+		return ERR_PTR(-EINVAL);
+
+	dev = df->dev.parent;
+
+	ret = dev_pm_opp_of_register_em(dev, NULL);
+	if (ret)
+		dev_dbg(dev, "Unable to register EM for devfreq cooling device (%d)\n",
+			ret);
+
+	cdev = of_devfreq_cooling_register_power(dev->of_node, df, dfc_power);
+
+	if (IS_ERR_OR_NULL(cdev))
+		em_dev_unregister_perf_domain(dev);
+
+	return cdev;
+}
+EXPORT_SYMBOL_GPL(devfreq_cooling_em_register);
+
 /**
  * devfreq_cooling_unregister() - Unregister devfreq cooling device.
  * @cdev: Pointer to devfreq cooling device to unregister.
+ *
+ * Unregisters devfreq cooling device and related Energy Model if it was
+ * present.
  */
 void devfreq_cooling_unregister(struct thermal_cooling_device *cdev)
 {
 	struct devfreq_cooling_device *dfc;
+	struct device *dev;
 
-	if (!cdev)
+	if (IS_ERR_OR_NULL(cdev))
 		return;
 
 	dfc = cdev->devdata;
+	dev = dfc->devfreq->dev.parent;
 
 	thermal_cooling_device_unregister(dfc->cdev);
 	ida_simple_remove(&devfreq_ida, dfc->id);
 	dev_pm_qos_remove_request(&dfc->req_max_freq);
+
+	em_dev_unregister_perf_domain(dev);
+
 	kfree(dfc->power_table);
 	kfree(dfc->freq_table);
 

include/linux/devfreq_cooling.h

@@ -65,6 +65,9 @@ struct thermal_cooling_device *
 of_devfreq_cooling_register(struct device_node *np, struct devfreq *df);
 struct thermal_cooling_device *devfreq_cooling_register(struct devfreq *df);
 void devfreq_cooling_unregister(struct thermal_cooling_device *dfc);
+struct thermal_cooling_device *
+devfreq_cooling_em_register(struct devfreq *df,
+			    struct devfreq_cooling_power *dfc_power);
 
 #else /* !CONFIG_DEVFREQ_THERMAL */
 
@@ -87,6 +90,13 @@ devfreq_cooling_register(struct devfreq *df)
 	return ERR_PTR(-EINVAL);
 }
 
+static inline struct thermal_cooling_device *
+devfreq_cooling_em_register(struct devfreq *df,
+			    struct devfreq_cooling_power *dfc_power)
+{
+	return ERR_PTR(-EINVAL);
+}
+
 static inline void
 devfreq_cooling_unregister(struct thermal_cooling_device *dfc)
 {