drivers: thermal: tsens: Create function to return sign-extended temperature

Hide the details of how to convert values read from TSENS HW to mCelsius
behind a function. All versions of the IP can be supported as a result.
Signed-off-by: Amit Kucheria <amit.kucheria@linaro.org>
Reviewed-by: Stephen Boyd <swboyd@chromium.org>
Signed-off-by: Daniel Lezcano <daniel.lezcano@linaro.org>
Link: https://lore.kernel.org/r/0689917475cf83b7e01f6978504fd37352a5e3ca.1572526427.git.amit.kucheria@linaro.org

drivers/thermal/qcom/tsens-common.c

@@ -84,13 +84,46 @@ static inline int code_to_degc(u32 adc_code, const struct tsens_sensor *s)
 	return degc;
 }
 
+/**
+ * tsens_hw_to_mC - Return sign-extended temperature in mCelsius.
+ * @s:     Pointer to sensor struct
+ * @field: Index into regmap_field array pointing to temperature data
+ *
+ * This function handles temperature returned in ADC code or deciCelsius
+ * depending on IP version.
+ *
+ * Return: Temperature in milliCelsius on success, a negative errno will
+ * be returned in error cases
+ */
+static int tsens_hw_to_mC(struct tsens_sensor *s, int field)
+{
+	struct tsens_priv *priv = s->priv;
+	u32 resolution;
+	u32 temp = 0;
+	int ret;
+
+	resolution = priv->fields[LAST_TEMP_0].msb -
+		priv->fields[LAST_TEMP_0].lsb;
+
+	ret = regmap_field_read(priv->rf[field], &temp);
+	if (ret)
+		return ret;
+
+	/* Convert temperature from ADC code to milliCelsius */
+	if (priv->feat->adc)
+		return code_to_degc(temp, s) * 1000;
+
+	/* deciCelsius -> milliCelsius along with sign extension */
+	return sign_extend32(temp, resolution) * 100;
+}
+
 int get_temp_tsens_valid(struct tsens_sensor *s, int *temp)
 {
 	struct tsens_priv *priv = s->priv;
 	int hw_id = s->hw_id;
 	u32 temp_idx = LAST_TEMP_0 + hw_id;
 	u32 valid_idx = VALID_0 + hw_id;
-	u32 last_temp = 0, valid, mask;
+	u32 valid;
 	int ret;
 
 	ret = regmap_field_read(priv->rf[valid_idx], &valid);
@@ -108,19 +141,7 @@ int get_temp_tsens_valid(struct tsens_sensor *s, int *temp)
 	}
 
 	/* Valid bit is set, OK to read the temperature */
-	ret = regmap_field_read(priv->rf[temp_idx], &last_temp);
-	if (ret)
-		return ret;
-
-	if (priv->feat->adc) {
-		/* Convert temperature from ADC code to milliCelsius */
-		*temp = code_to_degc(last_temp, s) * 1000;
-	} else {
-		mask = GENMASK(priv->fields[LAST_TEMP_0].msb,
-			       priv->fields[LAST_TEMP_0].lsb);
-		/* Convert temperature from deciCelsius to milliCelsius */
-		*temp = sign_extend32(last_temp, fls(mask) - 1) * 100;
-	}
+	*temp = tsens_hw_to_mC(s, temp_idx);
 
 	return 0;
 }