We can compute the full-scale values for power, voltages and current, and
apply them before conversion.
This way we sanitize the input from userspace a bit.
We can't however clamp the value for power, since that is represented in
micro-Watts. The full-scale power that can be represented is around 10480
Watts, which in micro-Watts ends up being around 10 billion micro-Watts.
Current and voltage is represented in millis, so these can be clamped.
Signed-off-by: Alexandru Ardelean <alexandru.ardelean@xxxxxxxxxx>
---
drivers/hwmon/ltc2945.c | 48 +++++++++++++++++++++++++++++++++++++++++
1 file changed, 48 insertions(+)
diff --git a/drivers/hwmon/ltc2945.c b/drivers/hwmon/ltc2945.c
index 42a59170da78..41df2c8b7673 100644
--- a/drivers/hwmon/ltc2945.c
+++ b/drivers/hwmon/ltc2945.c
@@ -58,6 +58,15 @@
#define CONTROL_MULT_SELECT (1 << 0)
#define CONTROL_TEST_MODE (1 << 4)
+/* Full scale ranges (page 4 of the datasheet) */
+
+#define LTC2945_VIN_FULL_SCALE_MV 102375
+#define LTC2945_ADIN_FULL_SCALE_MV 2048
+
+/* Power and current computed assuming a 1mOhm sense resistor */
+#define LTC2945_POWER_FULL_SCALE_UW 10485759375ULL
+#define LTC2945_SENSE_FULL_SCALE_MA 102375
+
/**
* struct ltc2945_state - driver instance specific data
* @regmap: regmap object to access device registers
@@ -154,6 +163,43 @@ static long long ltc2945_reg_to_val(struct device *dev, u8 reg)
return val;
}
+static unsigned long ltc2945_val_clamp(u8 reg, unsigned long val)
+{
+ switch (reg) {
+ case LTC2945_POWER_H:
+ case LTC2945_MAX_POWER_H:
+ case LTC2945_MIN_POWER_H:
+ case LTC2945_MAX_POWER_THRES_H:
+ case LTC2945_MIN_POWER_THRES_H:
+ /* No sense in clamping now, LTC2945_POWER_FULL_SCALE_UW is larger than UINT32_MAX */
+ return val;
+ case LTC2945_VIN_H:
+ case LTC2945_MAX_VIN_H:
+ case LTC2945_MIN_VIN_H:
+ case LTC2945_MAX_VIN_THRES_H:
+ case LTC2945_MIN_VIN_THRES_H:
+ return clamp_val(val, 0, LTC2945_VIN_FULL_SCALE_MV);
+ case LTC2945_ADIN_H:
+ case LTC2945_MAX_ADIN_H:
+ case LTC2945_MIN_ADIN_THRES_H:
+ case LTC2945_MAX_ADIN_THRES_H:
+ case LTC2945_MIN_ADIN_H:
+ return clamp_val(val, 0, LTC2945_ADIN_FULL_SCALE_MV);
+ case LTC2945_SENSE_H:
+ case LTC2945_MAX_SENSE_H:
+ case LTC2945_MIN_SENSE_H:
+ case LTC2945_MAX_SENSE_THRES_H:
+ case LTC2945_MIN_SENSE_THRES_H:
+ return clamp_val(val, 0, LTC2945_SENSE_FULL_SCALE_MA);
+ default:
+ /*
+ * This is unlikely to happen, and if it does, it should
+ * error out on the next call, we can't return negative here
+ */
+ return 0;
+ }
+}
+
static int ltc2945_val_to_reg(struct device *dev, u8 reg,
unsigned long val)
{
@@ -257,6 +303,8 @@ static ssize_t ltc2945_value_store(struct device *dev,
if (ret)
return ret;
+ val = ltc2945_val_clamp(reg, val);
+
/* convert to register value, then clamp and write result */
regval = ltc2945_val_to_reg(dev, reg, val);
if (is_power_reg(reg)) {
--
2.17.1
