hwmon: (ina3221) Fix negative limits

The result of an integer divide by an unsigned is undefined.
This causes unexpected results when writing negative values
into the limit registers.

Maintain the shunt_resistors variables as signed integer to avoid
the problem. Also, for simplicity and ease of use, clamp shunt
resistor value on writes instead of rejecting bad values.

Cc: Andrew F. Davis <afd@ti.com>
Acked-by: Andrew F. Davis <afd@ti.com>
Signed-off-by: Guenter Roeck <linux@roeck-us.net>

1 files changed, 6 insertions, 7 deletions

diff --git a/drivers/hwmon/ina3221.c b/drivers/hwmon/ina3221.c
index d055b6a2266b..e6b49500c52a 100644
--- a/drivers/hwmon/ina3221.c
+++ b/drivers/hwmon/ina3221.c
@@ -95,7 +95,7 @@ static const unsigned int register_channel[] = {
 struct ina3221_data {
         struct regmap *regmap;
         struct regmap_field *fields[F_MAX_FIELDS];
-        unsigned int shunt_resistors[INA3221_NUM_CHANNELS];
+        int shunt_resistors[INA3221_NUM_CHANNELS];
 };
 
 static int ina3221_read_value(struct ina3221_data *ina, unsigned int reg,
@@ -155,7 +155,7 @@ static ssize_t ina3221_show_current(struct device *dev,
         struct ina3221_data *ina = dev_get_drvdata(dev);
         unsigned int reg = sd_attr->index;
         unsigned int channel = register_channel[reg];
-        unsigned int resistance_uo = ina->shunt_resistors[channel];
+        int resistance_uo = ina->shunt_resistors[channel];
         int val, current_ma, voltage_nv, ret;
 
         ret = ina3221_read_value(ina, reg, &val);
@@ -176,7 +176,7 @@ static ssize_t ina3221_set_current(struct device *dev,
         struct ina3221_data *ina = dev_get_drvdata(dev);
         unsigned int reg = sd_attr->index;
         unsigned int channel = register_channel[reg];
-        unsigned int resistance_uo = ina->shunt_resistors[channel];
+        int resistance_uo = ina->shunt_resistors[channel];
         int val, current_ma, voltage_uv, ret;
 
         ret = kstrtoint(buf, 0, &current_ma);
@@ -223,15 +223,14 @@ static ssize_t ina3221_set_shunt(struct device *dev,
         struct sensor_device_attribute *sd_attr = to_sensor_dev_attr(attr);
         struct ina3221_data *ina = dev_get_drvdata(dev);
         unsigned int channel = sd_attr->index;
-        unsigned int val;
+        int val;
         int ret;
 
-        ret = kstrtouint(buf, 0, &val);
+        ret = kstrtoint(buf, 0, &val);
         if (ret)
                 return ret;
 
-        if (val == 0)
-                return -EINVAL;
+        val = clamp_val(val, 1, INT_MAX);
 
         ina->shunt_resistors[channel] = val;