[PATCH v7 2/2] thermal/drivers/imx: Add calibration offset support

[Haoning CHENG via B4 Relay]

From: Haoning CHENG <Haoning.CHENG@xxxxxxxxxxxx>

Some boards need a small per-design correction to align the reported CPU
temperature with board-level measurements.

Read the optional fsl,temp-calibration-offset-millicelsius property from
DT and apply it to the i.MX6/6SX/7D calibration formulas. When the
property is not present, the default offset remains 0, preserving the
current behaviour.

Signed-off-by: Haoning Cheng <Haoning.CHENG@xxxxxxxxxxxx>
---
 drivers/thermal/imx_thermal.c | 16 +++++++++++++---
 1 file changed, 13 insertions(+), 3 deletions(-)

diff --git a/drivers/thermal/imx_thermal.c b/drivers/thermal/imx_thermal.c
index 38c993d1bcb3..0a443e608957 100644
--- a/drivers/thermal/imx_thermal.c
+++ b/drivers/thermal/imx_thermal.c
@@ -207,6 +207,7 @@ struct imx_thermal_data {
 	struct regmap *tempmon;
 	u32 c1, c2; /* See formula in imx_init_calib() */
 	int temp_max;
+	s32 calibration_offset;
 	int alarm_temp;
 	int last_temp;
 	bool irq_enabled;
@@ -223,6 +224,7 @@ static void imx_set_panic_temp(struct imx_thermal_data *data,
 	struct regmap *map = data->tempmon;
 	int critical_value;
 
+	panic_temp -= data->calibration_offset;
 	critical_value = (data->c2 - panic_temp) / data->c1;
 
 	regmap_write(map, soc_data->panic_alarm_ctrl + REG_CLR,
@@ -239,11 +241,14 @@ static void imx_set_alarm_temp(struct imx_thermal_data *data,
 	int alarm_value;
 
 	data->alarm_temp = alarm_temp;
+	alarm_temp -= data->calibration_offset;
 
-	if (data->socdata->version == TEMPMON_IMX7D)
-		alarm_value = alarm_temp / 1000 + data->c1 - 25;
-	else
+	if (data->socdata->version == TEMPMON_IMX7D) {
+		alarm_value = DIV_ROUND_UP(alarm_temp, 1000) + data->c1 - 25;
+		alarm_value = clamp(alarm_value, 0, 0x1ff);
+	} else {
 		alarm_value = (data->c2 - alarm_temp) / data->c1;
+	}
 
 	regmap_write(map, soc_data->high_alarm_ctrl + REG_CLR,
 		     soc_data->high_alarm_mask);
@@ -277,6 +282,7 @@ static int imx_get_temp(struct thermal_zone_device *tz, int *temp)
 		*temp = (n_meas - data->c1 + 25) * 1000;
 	else
 		*temp = data->c2 - n_meas * data->c1;
+	*temp += data->calibration_offset;
 
 	/* Update alarm value to next higher trip point for TEMPMON_IMX6Q */
 	if (data->socdata->version == TEMPMON_IMX6Q) {
@@ -629,6 +635,10 @@ static int imx_thermal_probe(struct platform_device *pdev)
 
 	platform_set_drvdata(pdev, data);
 
+	of_property_read_s32(dev->of_node,
+			     "fsl,temp-calibration-offset-millicelsius",
+			     &data->calibration_offset);
+
 	if (of_property_present(dev->of_node, "nvmem-cells")) {
 		ret = imx_init_from_nvmem_cells(pdev);
 		if (ret)

-- 
2.43.0