[RFC 1/1] thermal: rcar-thermal: add cpu cooling

[Patrick Titiano <ptitiano@baylibre.com>]

Renesas RCar platforms only register a thermal zone, but do not implement
any thermal management.
Use CPU cooling (CPUFreq DVFS driver) to implement thermal management.
Register cpufreq cooling device, add passive trip point and bind it
to thermal zone 0.
Passive trip point temperature is set to 70C, but is adjustable
via sysfs to facilitate experimentation and platform tuning.

Signed-off-by: Patrick Titiano <ptitiano@baylibre.com>
---
 drivers/thermal/rcar_thermal.c | 103 ++++++++++++++++++++++++++++++++++++++---
 1 file changed, 96 insertions(+), 7 deletions(-)

diff --git a/drivers/thermal/rcar_thermal.c b/drivers/thermal/rcar_thermal.c
index 187693c..0f953cf0 100644
--- a/drivers/thermal/rcar_thermal.c
+++ b/drivers/thermal/rcar_thermal.c
@@ -31,6 +31,8 @@
 #include <linux/slab.h>
 #include <linux/spinlock.h>
 #include <linux/thermal.h>
+#include <linux/cpufreq.h>
+#include <linux/cpu_cooling.h>
 
 #define IDLE_INTERVAL	5000
 
@@ -62,11 +64,14 @@ struct rcar_thermal_priv {
 	void __iomem *base;
 	struct rcar_thermal_common *common;
 	struct thermal_zone_device *zone;
+	struct thermal_cooling_device *cpucooldev;
 	struct delayed_work work;
 	struct mutex lock;
 	struct list_head list;
 	int id;
 	int ctemp;
+	int trip_ctemp_passive;
+	int trip_ctemp_critical;
 };
 
 #define rcar_thermal_for_each_priv(pos, common)	\
@@ -78,6 +83,9 @@ struct rcar_thermal_priv {
 #define rcar_has_irq_support(priv)	((priv)->common->base)
 #define rcar_id_to_shift(priv)		((priv)->id * 8)
 
+#define TRIP_CTEMP_PASSIVE		MCELSIUS(70)
+#define TRIP_CTEMP_CRITICAL		MCELSIUS(90)
+
 #ifdef DEBUG
 # define rcar_force_update_temp(priv)	1
 #else
@@ -224,9 +232,11 @@ static int rcar_thermal_get_trip_type(struct thermal_zone_device *zone,
 	struct rcar_thermal_priv *priv = rcar_zone_to_priv(zone);
 	struct device *dev = rcar_priv_to_dev(priv);
 
-	/* see rcar_thermal_get_temp() */
 	switch (trip) {
-	case 0: /* +90 <= temp */
+	case 0:
+		*type = THERMAL_TRIP_PASSIVE;
+		break;
+	case 1:
 		*type = THERMAL_TRIP_CRITICAL;
 		break;
 	default:
@@ -243,15 +253,35 @@ static int rcar_thermal_get_trip_temp(struct thermal_zone_device *zone,
 	struct rcar_thermal_priv *priv = rcar_zone_to_priv(zone);
 	struct device *dev = rcar_priv_to_dev(priv);
 
-	/* see rcar_thermal_get_temp() */
+	mutex_lock(&priv->lock);
 	switch (trip) {
-	case 0: /* +90 <= temp */
-		*temp = MCELSIUS(90);
+	case 0:
+		*temp = priv->trip_ctemp_passive;
+		break;
+	case 1:
+		*temp = priv->trip_ctemp_critical;
 		break;
 	default:
 		dev_err(dev, "rcar driver trip error\n");
 		return -EINVAL;
 	}
+	mutex_unlock(&priv->lock);
+
+	return 0;
+}
+
+static int rcar_thermal_set_trip_temp(struct thermal_zone_device *zone,
+				      int trip, unsigned long temp)
+{
+	struct rcar_thermal_priv *priv = rcar_zone_to_priv(zone);
+
+	/* Do not allow PASSIVE trip temperature > CRITICAL trip temperature */
+	if (temp >= priv->trip_ctemp_critical)
+		return -EINVAL;
+
+	mutex_lock(&priv->lock);
+	priv->trip_ctemp_passive = temp;
+	mutex_unlock(&priv->lock);
 
 	return 0;
 }
@@ -274,11 +304,52 @@ static int rcar_thermal_notify(struct thermal_zone_device *zone,
 	return 0;
 }
 
+static int rcar_thermal_bind(struct thermal_zone_device *zone,
+			   struct thermal_cooling_device *cdev)
+{
+	int ret;
+
+	ret = thermal_zone_bind_cooling_device(zone, 0, cdev,
+	/* bind with min and max states defined by cpu_cooling */
+						THERMAL_NO_LIMIT,
+						THERMAL_NO_LIMIT);
+	ret += thermal_zone_bind_cooling_device(zone, 1, cdev,
+	/* bind with min and max states defined by cpu_cooling */
+						THERMAL_NO_LIMIT,
+						THERMAL_NO_LIMIT);
+
+	return ret;
+}
+
+/* Unbind callback functions for thermal zone */
+static int rcar_thermal_unbind(struct thermal_zone_device *zone,
+			     struct thermal_cooling_device *cdev)
+{
+	int ret;
+
+	ret = thermal_zone_unbind_cooling_device(zone, 0, cdev);
+	ret += thermal_zone_unbind_cooling_device(zone, 1, cdev);
+
+	return ret;
+}
+
+static int rcar_thermal_get_mode(struct thermal_zone_device *zone,
+			 enum thermal_device_mode *mode)
+{
+	*mode = THERMAL_DEVICE_ENABLED;
+
+	return 0;
+}
+
 static struct thermal_zone_device_ops rcar_thermal_zone_ops = {
+	.get_mode       = rcar_thermal_get_mode,
 	.get_temp	= rcar_thermal_get_temp,
 	.get_trip_type	= rcar_thermal_get_trip_type,
 	.get_trip_temp	= rcar_thermal_get_trip_temp,
+	.set_trip_temp	= rcar_thermal_set_trip_temp,
 	.notify		= rcar_thermal_notify,
+	.bind           = rcar_thermal_bind,
+	.unbind         = rcar_thermal_unbind,
 };
 
 /*
@@ -375,6 +446,12 @@ static int rcar_thermal_probe(struct platform_device *pdev)
 	int i;
 	int ret = -ENODEV;
 	int idle = IDLE_INTERVAL;
+	struct cpumask clip_cpus;
+
+	if (!cpufreq_get_current_driver()) {
+		dev_dbg(dev, "no cpufreq driver yet, deferring probe\n");
+		return -EPROBE_DEFER;
+	}
 
 	common = devm_kzalloc(dev, sizeof(*common), GFP_KERNEL);
 	if (!common) {
@@ -456,13 +533,24 @@ static int rcar_thermal_probe(struct platform_device *pdev)
 
 		priv->common = common;
 		priv->id = i;
+		priv->trip_ctemp_passive = TRIP_CTEMP_PASSIVE;
+		priv->trip_ctemp_critical = TRIP_CTEMP_CRITICAL;
 		mutex_init(&priv->lock);
 		INIT_LIST_HEAD(&priv->list);
 		INIT_DELAYED_WORK(&priv->work, rcar_thermal_work);
 		rcar_thermal_update_temp(priv);
 
+		cpumask_set_cpu(0, &clip_cpus);
+		priv->cpucooldev = cpufreq_cooling_register(&clip_cpus);
+		if (IS_ERR(priv->cpucooldev)) {
+			ret = PTR_ERR(priv->cpucooldev);
+			dev_err(dev, "failed to register cpufreq cooling device (%d)\n",
+				ret);
+			goto error_unpm;
+		}
+
 		priv->zone = thermal_zone_device_register("rcar_thermal",
-						1, 0, priv,
+						2, 1, priv,
 						&rcar_thermal_zone_ops, NULL, 0,
 						idle);
 		if (IS_ERR(priv->zone)) {
@@ -478,7 +566,6 @@ static int rcar_thermal_probe(struct platform_device *pdev)
 	}
 
 	platform_set_drvdata(pdev, common);
-
 	dev_info(dev, "%d sensor probed\n", i);
 
 	return 0;
@@ -513,6 +600,8 @@ static int rcar_thermal_remove(struct platform_device *pdev)
 			rcar_thermal_irq_disable(priv);
 	}
 
+	cpufreq_cooling_unregister(priv->cpucooldev);
+
 	pm_runtime_put_sync(dev);
 	pm_runtime_disable(dev);
 
-- 
1.8.3.2