[PATCH v4 2/2] hwmon: scmi: Scale values to target desired HWMON units

Florian Fainelli
2019-05-08T17:00:47Z

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 | 46 ++++++++++++++++++++++++++++++++++++++
1 file changed, 46 insertions(+)

diff --git a/drivers/hwmon/scmi-hwmon.c b/drivers/hwmon/scmi-hwmon.c
index a80183a488c5..4399372e2131 100644
--- a/drivers/hwmon/scmi-hwmon.c
+++ b/drivers/hwmon/scmi-hwmon.c
@@ -7,6 +7,7 @@
*/

#include <linux/hwmon.h>
+#include <linux/limits.h>
#include <linux/module.h>
#include <linux/scmi_protocol.h>
#include <linux/slab.h>
@@ -18,6 +19,47 @@ struct scmi_sensors {
const struct scmi_sensor_info **info[hwmon_max];
};

+static inline u64 __pow10(u8 x)
+{
+ u64 r = 1;
+
+ while (x--)
+ r *= 10;
+
+ return r;
+}
+
+static int scmi_hwmon_scale(const struct scmi_sensor_info *sensor, u64 *value)
+{
+ s8 scale = sensor->scale;
+ u64 f;
+
+ switch (sensor->type) {
+ case TEMPERATURE_C:
+ case VOLTAGE:
+ case CURRENT:
+ scale += 3;
+ break;
+ case POWER:
+ case ENERGY:
+ scale += 6;
+ break;
+ default:
+ break;
+ }
+
+ f = __pow10(abs(scale));
+ if (f == U64_MAX)
+ return -E2BIG;
+
+ if (scale > 0)
+ *value *= f;
+ else
+ *value = div64_u64(*value, f);
+
+ return 0;
+}
+
static int scmi_hwmon_read(struct device *dev, enum hwmon_sensor_types type,
u32 attr, int channel, long *val)
{
@@ -29,6 +71,10 @@ 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)
+ return ret;
+
+ ret = scmi_hwmon_scale(sensor, value);
if (!ret)
*val = value;

--
2.17.1