[PATCH v2 3/3] hwmon: scmi: Scale values to target desired HWMON units

[Florian Fainelli <f.fainelli@gmail.com>]

If the SCMI firmware implementation is reporting values in a scale that
is different from the HWMON units, we need to scale up or down the value
according to how far appart they are.

Signed-off-by: Florian Fainelli <f.fainelli@gmail.com>
---
 drivers/hwmon/scmi-hwmon.c | 30 +++++++++++++++++++++++++++++-
 1 file changed, 29 insertions(+), 1 deletion(-)

diff --git a/drivers/hwmon/scmi-hwmon.c b/drivers/hwmon/scmi-hwmon.c
index a80183a488c5..5c244053efc8 100644
--- a/drivers/hwmon/scmi-hwmon.c
+++ b/drivers/hwmon/scmi-hwmon.c
@@ -18,6 +18,34 @@ struct scmi_sensors {
 	const struct scmi_sensor_info **info[hwmon_max];
 };
 
+static u64 scmi_hwmon_scale(const struct scmi_sensor_info *sensor, u64 value)
+{
+	s8 scale = sensor->scale;
+	unsigned long long f;
+
+	switch (sensor->type) {
+	case TEMPERATURE_C:
+	case VOLTAGE:
+	case CURRENT:
+		scale += 3;
+		break;
+	case POWER:
+	case ENERGY:
+		scale += 6;
+		break;
+	default:
+		break;
+	}
+
+	__pow10(abs(scale), f);
+	if (scale > 0)
+		value *= f;
+	else
+		do_div(value, f);
+
+        return value;
+}
+
 static int scmi_hwmon_read(struct device *dev, enum hwmon_sensor_types type,
 			   u32 attr, int channel, long *val)
 {
@@ -30,7 +58,7 @@ static int scmi_hwmon_read(struct device *dev, enum hwmon_sensor_types type,
 	sensor = *(scmi_sensors->info[type] + channel);
 	ret = h->sensor_ops->reading_get(h, sensor->id, false, &value);
 	if (!ret)
-		*val = value;
+		*val = scmi_hwmon_scale(sensor, value);
 
 	return ret;
 }
-- 
2.17.1