[PATCH v2 4/9] imx: thermal: Configure trip point from DT

[Francesco Dolcini <francesco.dolcini@toradex.com>]

Allow over-writing critical and passive trip point for each
temperature grade from the device tree, by default the pre-existing
hard-coded trip points are used.

This change enables configuring the system thermal characteristics into
the system-specific device tree instead of relying on global hard-coded
temperature thresholds that does not take into account the specific
system thermal design.

Signed-off-by: Francesco Dolcini <francesco.dolcini@toradex.com>
---
v2:
 - return immediately if no thermal node present in the dts
 - use dev_info instead of dev_dbg if there is an invalid trip
 - additional comment in case passive trip point is higher than critical
---
 drivers/thermal/imx_thermal.c | 58 +++++++++++++++++++++++++++++++++++
 1 file changed, 58 insertions(+)

diff --git a/drivers/thermal/imx_thermal.c b/drivers/thermal/imx_thermal.c
index 16663373b682..a964baf802fc 100644
--- a/drivers/thermal/imx_thermal.c
+++ b/drivers/thermal/imx_thermal.c
@@ -17,6 +17,8 @@
 #include <linux/nvmem-consumer.h>
 #include <linux/pm_runtime.h>
 
+#include "thermal_core.h"
+
 #define REG_SET		0x4
 #define REG_CLR		0x8
 #define REG_TOG		0xc
@@ -479,36 +481,92 @@ static int imx_init_calib(struct platform_device *pdev, u32 ocotp_ana1)
 	return 0;
 }
 
+static void imx_init_temp_from_of(struct platform_device *pdev, const char *name)
+{
+	struct imx_thermal_data *data = platform_get_drvdata(pdev);
+	struct device_node *thermal, *trips, *trip_point;
+
+	thermal = of_get_child_by_name(pdev->dev.of_node, name);
+	if (!thermal)
+		return;
+
+	trips = of_get_child_by_name(thermal, "trips");
+
+	for_each_child_of_node(trips, trip_point) {
+		struct thermal_trip t;
+
+		if (thermal_of_populate_trip(trip_point, &t))
+			continue;
+
+		switch (t.type) {
+		case THERMAL_TRIP_PASSIVE:
+			data->temp_passive = t.temperature;
+			break;
+		case THERMAL_TRIP_CRITICAL:
+			data->temp_critical = t.temperature;
+			break;
+		default:
+			dev_info(&pdev->dev, "Ignoring trip type %d\n", t.type);
+			break;
+		}
+	};
+
+	of_node_put(trips);
+	of_node_put(thermal);
+
+	if (data->temp_passive >= data->temp_critical) {
+		dev_warn(&pdev->dev,
+			 "passive trip point must be lower than critical, fixing it up\n");
+		/*
+		 * In case of misconfiguration set passive temperature to
+		 * 5°C less than critical, this seems like a reasonable
+		 * default and the same is done when no thermal trips are
+		 * available in the device tree.
+		 */
+		data->temp_passive = data->temp_critical - (1000 * 5);
+	}
+}
+
 static void imx_init_temp_grade(struct platform_device *pdev, u32 ocotp_mem0)
 {
 	struct imx_thermal_data *data = platform_get_drvdata(pdev);
+	const char *thermal_node_name;
 
 	/* The maximum die temp is specified by the Temperature Grade */
 	switch ((ocotp_mem0 >> 6) & 0x3) {
 	case 0: /* Commercial (0 to 95 °C) */
+		thermal_node_name = "commercial-thermal";
 		data->temp_grade = "Commercial";
 		data->temp_max = 95000;
 		break;
 	case 1: /* Extended Commercial (-20 °C to 105 °C) */
+		thermal_node_name = "extended-commercial-thermal";
 		data->temp_grade = "Extended Commercial";
 		data->temp_max = 105000;
 		break;
 	case 2: /* Industrial (-40 °C to 105 °C) */
+		thermal_node_name = "industrial-thermal";
 		data->temp_grade = "Industrial";
 		data->temp_max = 105000;
 		break;
 	case 3: /* Automotive (-40 °C to 125 °C) */
+		thermal_node_name = "automotive-thermal";
 		data->temp_grade = "Automotive";
 		data->temp_max = 125000;
 		break;
 	}
 
 	/*
+	 * Set defaults trips
+	 *
 	 * Set the critical trip point at 5 °C under max
 	 * Set the passive trip point at 10 °C under max (changeable via sysfs)
 	 */
 	data->temp_critical = data->temp_max - (1000 * 5);
 	data->temp_passive = data->temp_max - (1000 * 10);
+
+	/* Override critical/passive temperature from devicetree */
+	imx_init_temp_from_of(pdev, thermal_node_name);
 }
 
 static int imx_init_from_tempmon_data(struct platform_device *pdev)
-- 
2.25.1