[PATCH v2 14/15] drivers: thermal: tsens: Create function to return sign-extended temperature

[Amit Kucheria <amit.kucheria@linaro.org>]

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>
---
 drivers/thermal/qcom/tsens-common.c | 50 +++++++++++++++++++++--------
 drivers/thermal/qcom/tsens.h        |  2 ++
 2 files changed, 38 insertions(+), 14 deletions(-)

diff --git a/drivers/thermal/qcom/tsens-common.c b/drivers/thermal/qcom/tsens-common.c
index ea2c46cc6a66a..06b44cfd5eab9 100644
--- a/drivers/thermal/qcom/tsens-common.c
+++ b/drivers/thermal/qcom/tsens-common.c
@@ -84,13 +84,43 @@ 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 temp = 0;
+	int ret;
+
+	ret = regmap_field_read(priv->rf[field], &temp);
+	if (ret)
+		return ret;
+
+	if (priv->feat->adc) {
+		/* Convert temperature from ADC code to milliCelsius */
+		return code_to_degc(temp, s) * 1000;
+	}
+
+	/* deciCelsius -> milliCelsius along with sign extension */
+	return sign_extend32(temp, priv->tempres) * 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 +138,7 @@ 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;
 }
@@ -310,6 +328,10 @@ int __init init_common(struct tsens_priv *priv)
 			goto err_put_device;
 		}
 	}
+
+	/* Save away resolution of signed temperature value for this IP */
+	priv->tempres = priv->fields[LAST_TEMP_0].msb - priv->fields[LAST_TEMP_0].lsb;
+
 	for (i = 0, j = VALID_0; i < priv->feat->max_sensors; i++, j++) {
 		priv->rf[j] = devm_regmap_field_alloc(dev, priv->tm_map,
 						      priv->fields[j]);
diff --git a/drivers/thermal/qcom/tsens.h b/drivers/thermal/qcom/tsens.h
index e1d6af71b2b9a..409395e436f32 100644
--- a/drivers/thermal/qcom/tsens.h
+++ b/drivers/thermal/qcom/tsens.h
@@ -283,6 +283,7 @@ struct tsens_context {
  * struct tsens_priv - private data for each instance of the tsens IP
  * @dev: pointer to struct device
  * @num_sensors: number of sensors enabled on this device
+ * @tempres: number of bits used to represent signed temperature (resolution)
  * @tm_map: pointer to TM register address space
  * @srot_map: pointer to SROT register address space
  * @tm_offset: deal with old device trees that don't address TM and SROT
@@ -299,6 +300,7 @@ struct tsens_context {
 struct tsens_priv {
 	struct device			*dev;
 	u32				num_sensors;
+	u32				tempres;
 	struct regmap			*tm_map;
 	struct regmap			*srot_map;
 	u32				tm_offset;
-- 
2.17.1