[PATCH v3 3/5] hwmon: ltc2945: Handle error case in ltc2945_value_store

[Jonathan Cormier <jcormier@xxxxxxxxxxxxxxxx>]

ltc2945_val_to_reg errors were not being handled
which would have resulted in register being set to
0 (clamped) instead of being left alone.

Change reg_to_val and val_to_reg to return values
via parameters to make it more obvious when an
error case isn't handled. Also to allow
the regval type to be the correct sign in prep for
next commits.

Fixes: 6700ce035f83 ("hwmon: Driver for Linear Technologies LTC2945")

Signed-off-by: Jonathan Cormier <jcormier@xxxxxxxxxxxxxxxx>
---
 drivers/hwmon/ltc2945.c | 30 ++++++++++++++++++------------
 1 file changed, 18 insertions(+), 12 deletions(-)

diff --git a/drivers/hwmon/ltc2945.c b/drivers/hwmon/ltc2945.c
index 9af3e3821152..c66acf8d2124 100644
--- a/drivers/hwmon/ltc2945.c
+++ b/drivers/hwmon/ltc2945.c
@@ -70,12 +70,12 @@ static inline bool is_power_reg(u8 reg)
 }
 
 /* Return the value from the given register in uW, mV, or mA */
-static long long ltc2945_reg_to_val(struct device *dev, u8 reg)
+static int ltc2945_reg_to_val(struct device *dev, u8 reg, u64 *regval)
 {
 	struct regmap *regmap = dev_get_drvdata(dev);
 	unsigned int control;
 	u8 buf[3];
-	long long val;
+	u64 val;
 	int ret;
 
 	ret = regmap_bulk_read(regmap, reg, buf,
@@ -148,11 +148,12 @@ static long long ltc2945_reg_to_val(struct device *dev, u8 reg)
 	default:
 		return -EINVAL;
 	}
-	return val;
+	*regval = val;
+	return 0;
 }
 
 static int ltc2945_val_to_reg(struct device *dev, u8 reg,
-			      unsigned long val)
+			      unsigned long val, unsigned long *regval)
 {
 	struct regmap *regmap = dev_get_drvdata(dev);
 	unsigned int control;
@@ -220,19 +221,21 @@ static int ltc2945_val_to_reg(struct device *dev, u8 reg,
 	default:
 		return -EINVAL;
 	}
-	return val;
+	*regval = val;
+	return 0;
 }
 
 static ssize_t ltc2945_value_show(struct device *dev,
 				  struct device_attribute *da, char *buf)
 {
 	struct sensor_device_attribute *attr = to_sensor_dev_attr(da);
-	long long value;
+	int ret;
+	u64 value;
 
-	value = ltc2945_reg_to_val(dev, attr->index);
-	if (value < 0)
-		return value;
-	return sysfs_emit(buf, "%lld\n", value);
+	ret = ltc2945_reg_to_val(dev, attr->index, &value);
+	if (ret < 0)
+		return ret;
+	return sysfs_emit(buf, "%llu\n", value);
 }
 
 static ssize_t ltc2945_value_store(struct device *dev,
@@ -245,7 +248,7 @@ static ssize_t ltc2945_value_store(struct device *dev,
 	unsigned long val;
 	u8 regbuf[3];
 	int num_regs;
-	int regval;
+	unsigned long regval;
 	int ret;
 
 	ret = kstrtoul(buf, 10, &val);
@@ -253,7 +256,10 @@ static ssize_t ltc2945_value_store(struct device *dev,
 		return ret;
 
 	/* convert to register value, then clamp and write result */
-	regval = ltc2945_val_to_reg(dev, reg, val);
+	ret = ltc2945_val_to_reg(dev, reg, val, &regval);
+	if (ret < 0)
+		return ret;
+
 	if (is_power_reg(reg)) {
 		regval = clamp_val(regval, 0, 0xffffff);
 		regbuf[0] = regval >> 16;
-- 
2.25.1