thermal/drivers/qcom/tsens-v0_1: Add mdm9607 correction offsets

According to the msm-3.18 vendor kernel from Qualcomm, mdm9607 needs
"correction factors" to adjust for additional offsets observed after the
factory calibration values in the fuses [1, 2].

The fixed offsets should be applied unless there is a special
calibration mode value that indicates that no offsets are needed [3].

Note that the new calibration mode values are called differently in this
patch compared to the vendor kernel:
  - TSENS_TWO_POINT_CALIB_N_WA        -> ONE_PT_CALIB2_NO_OFFSET
  - TSENS_TWO_POINT_CALIB_N_OFFSET_WA -> TWO_PT_CALIB_NO_OFFSET
This is because close inspection of the calibration function [3] reveals
that TSENS_TWO_POINT_CALIB_N_WA is actually a "one point" calibration
because the if statements skip all "point2" related code for it.

[1]: https://git.codelinaro.org/clo/la/kernel/msm-3.18/-/commit/d9d2db1b82bf3f72f5de0803d55e6849eb5b671e
[2]: https://git.codelinaro.org/clo/la/kernel/msm-3.18/-/commit/d75aef53a760e8ff7bac54049d00c8b2ee1b193e
[3]: https://git.codelinaro.org/clo/la/kernel/msm-3.18/-/blob/LE.UM.4.3.2.r1-04200-9x07/drivers/thermal/msm-tsens.c#L2987-3136

Fixes: a2149ab8 ("thermal/drivers/qcom/tsens-v0_1: Add support for MDM9607")
Reviewed-by: Konrad Dybcio <konrad.dybcio@linaro.org>
Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Signed-off-by: Stephan Gerhold <stephan.gerhold@kernkonzept.com>
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Link: https://lore.kernel.org/r/20230508-msm8909-tsens-v5-3-5eb632235ba7@kernkonzept.com

drivers/thermal/qcom/tsens-v0_1.c

@@ -241,6 +241,17 @@ static int __init init_9607(struct tsens_priv *priv)
 	for (i = 0; i < priv->num_sensors; ++i)
 		priv->sensor[i].slope = 3000;
 
+	priv->sensor[0].p1_calib_offset = 1;
+	priv->sensor[0].p2_calib_offset = 1;
+	priv->sensor[1].p1_calib_offset = -4;
+	priv->sensor[1].p2_calib_offset = -2;
+	priv->sensor[2].p1_calib_offset = 4;
+	priv->sensor[2].p2_calib_offset = 8;
+	priv->sensor[3].p1_calib_offset = -3;
+	priv->sensor[3].p2_calib_offset = -5;
+	priv->sensor[4].p1_calib_offset = -4;
+	priv->sensor[4].p2_calib_offset = -4;
+
 	return init_common(priv);
 }
 

drivers/thermal/qcom/tsens.c

@@ -134,10 +134,12 @@ int tsens_read_calibration(struct tsens_priv *priv, int shift, u32 *p1, u32 *p2,
 			p1[i] = p1[i] + (base1 << shift);
 		break;
 	case TWO_PT_CALIB:
+	case TWO_PT_CALIB_NO_OFFSET:
 		for (i = 0; i < priv->num_sensors; i++)
 			p2[i] = (p2[i] + base2) << shift;
 		fallthrough;
 	case ONE_PT_CALIB2:
+	case ONE_PT_CALIB2_NO_OFFSET:
 		for (i = 0; i < priv->num_sensors; i++)
 			p1[i] = (p1[i] + base1) << shift;
 		break;
@@ -149,6 +151,18 @@ int tsens_read_calibration(struct tsens_priv *priv, int shift, u32 *p1, u32 *p2,
 		}
 	}
 
+	/* Apply calibration offset workaround except for _NO_OFFSET modes */
+	switch (mode) {
+	case TWO_PT_CALIB:
+		for (i = 0; i < priv->num_sensors; i++)
+			p2[i] += priv->sensor[i].p2_calib_offset;
+		fallthrough;
+	case ONE_PT_CALIB2:
+		for (i = 0; i < priv->num_sensors; i++)
+			p1[i] += priv->sensor[i].p1_calib_offset;
+		break;
+	}
+
 	return mode;
 }
 
@@ -254,7 +268,7 @@ void compute_intercept_slope(struct tsens_priv *priv, u32 *p1,
 
 		if (!priv->sensor[i].slope)
 			priv->sensor[i].slope = SLOPE_DEFAULT;
-		if (mode == TWO_PT_CALIB) {
+		if (mode == TWO_PT_CALIB || mode == TWO_PT_CALIB_NO_OFFSET) {
 			/*
 			 * slope (m) = adc_code2 - adc_code1 (y2 - y1)/
 			 *	temp_120_degc - temp_30_degc (x2 - x1)

drivers/thermal/qcom/tsens.h

@@ -10,6 +10,8 @@
 #define ONE_PT_CALIB		0x1
 #define ONE_PT_CALIB2		0x2
 #define TWO_PT_CALIB		0x3
+#define ONE_PT_CALIB2_NO_OFFSET	0x6
+#define TWO_PT_CALIB_NO_OFFSET	0x7
 #define CAL_DEGC_PT1		30
 #define CAL_DEGC_PT2		120
 #define SLOPE_FACTOR		1000
@@ -57,6 +59,8 @@ struct tsens_sensor {
 	unsigned int			hw_id;
 	int				slope;
 	u32				status;
+	int				p1_calib_offset;
+	int				p2_calib_offset;
 };
 
 /**