[PATCH 5/9] thermal/drivers/mediatek/lvts: Add lvts_temp_to_raw variant for positive temp_factor

[Laura Nao]

The current lvts_temp_to_raw() implementation assumes a negative
temperature-to-raw slope (temp_factor), which holds for the SoCs
currently supported by the driver. However, this assumption breaks on
MT8196/MT6991, where the slope is positive.

Add a variant of the function that inverts the calculation logic
accordingly. This ensures accurate raw value generation for temperature
thresholds,avoiding spurious thermal interrupts or unintended hardware
resets on MT8196/MT6991.

Signed-off-by: Laura Nao <laura.nao at collabora.com>
---
 drivers/thermal/mediatek/lvts_thermal.c | 12 ++++++++++++
 1 file changed, 12 insertions(+)

diff --git a/drivers/thermal/mediatek/lvts_thermal.c b/drivers/thermal/mediatek/lvts_thermal.c
index db83137c7537..3c34956e37c1 100644
--- a/drivers/thermal/mediatek/lvts_thermal.c
+++ b/drivers/thermal/mediatek/lvts_thermal.c
@@ -296,6 +296,18 @@ static u32 lvts_temp_to_raw(int temperature, int temp_factor)
 	return div_s64(raw_temp, -temp_factor);
 }
 
+static u32 lvts_temp_to_raw_v2(int temperature, int temp_factor)
+{
+	u32 raw_temp;
+
+	if (temp_factor == 0)
+		return temperature;
+
+	raw_temp = temperature - golden_temp_offset;
+
+	return div_s64((s64)temp_factor << 14, raw_temp);
+}
+
 static int lvts_get_temp(struct thermal_zone_device *tz, int *temp)
 {
 	struct lvts_sensor *lvts_sensor = thermal_zone_device_priv(tz);
-- 
2.39.5