hwmon: (pmbus) Fix LINEAR16 data format

LINEAR16 data format is unsigned, not signed. Impact is that affected
attributes report negative values in the upper half of the supported
value range.

Signed-off-by: Guenter Roeck <guenter.roeck@ericsson.com>

1 files changed, 17 insertions, 14 deletions

diff --git a/drivers/hwmon/pmbus_core.c b/drivers/hwmon/pmbus_core.c
index 92540c9cd34e..6474512f49b0 100644
--- a/drivers/hwmon/pmbus_core.c
+++ b/drivers/hwmon/pmbus_core.c
@@ -359,20 +359,21 @@ static struct pmbus_data *pmbus_update_device(struct device *dev)
 static int pmbus_reg2data_linear(struct pmbus_data *data,
                                  struct pmbus_sensor *sensor)
 {
-        s16 exponent, mantissa;
+        s16 exponent;
+        s32 mantissa;
         long val;
 
-        if (sensor->class == PSC_VOLTAGE_OUT) {
+        if (sensor->class == PSC_VOLTAGE_OUT) { /* LINEAR16 */
                 exponent = data->exponent;
-                mantissa = (s16) sensor->data;
-        } else {
+                mantissa = (u16) sensor->data;
+        } else {                                /* LINEAR11 */
                 exponent = (sensor->data >> 11) & 0x001f;
                 mantissa = sensor->data & 0x07ff;
 
                 if (exponent > 0x0f)
                         exponent |= 0xffe0;     /* sign extend exponent */
                 if (mantissa > 0x03ff)
-                        mantissa |= 0xf800;     /* sign extend mantissa */
+                        mantissa |= 0xfffff800; /* sign extend mantissa */
         }
 
         val = mantissa;
@@ -454,19 +455,18 @@ static int pmbus_reg2data(struct pmbus_data *data, struct pmbus_sensor *sensor)
 static u16 pmbus_data2reg_linear(struct pmbus_data *data,
                                  enum pmbus_sensor_classes class, long val)
 {
-        s16 exponent = 0, mantissa = 0;
+        s16 exponent = 0, mantissa;
         bool negative = false;
 
         /* simple case */
         if (val == 0)
                 return 0;
 
-        if (val < 0) {
-                negative = true;
-                val = -val;
-        }
-
         if (class == PSC_VOLTAGE_OUT) {
+                /* LINEAR16 does not support negative voltages */
+                if (val < 0)
+                        return 0;
+
                 /*
                  * For a static exponents, we don't have a choice
                  * but to adjust the value to it.
@@ -476,9 +476,12 @@ static u16 pmbus_data2reg_linear(struct pmbus_data *data,
                 else
                         val >>= data->exponent;
                 val = DIV_ROUND_CLOSEST(val, 1000);
-                if (val > 0x7fff)
-                        val = 0x7fff;
-                return negative ? -val : val;
+                return val & 0xffff;
+        }
+
+        if (val < 0) {
+                negative = true;
+                val = -val;
         }
 
         /* Power is in uW. Convert to mW before converting. */