hwmon: (ina2xx) Add device tree support to pass alert polarity

The INA230 has an Alert pin which is asserted when the alert
function selected in the Mask/Enable register exceeds the
value programmed into the Alert Limit register. Assertion is based
on the Alert Polarity Bit (APOL, bit 1 of the Mask/Enable register).
It is default set to value 0 i.e Normal (active-low open collector).
However, hardware can be designed in such a way that expects Alert pin
to become active high if a user-defined threshold in Alert limit
register has been exceeded. This patch adds a way to pass alert polarity
value to the driver via device tree.

Signed-off-by: Amna Waseem <Amna.Waseem@axis.com>
Link: https://lore.kernel.org/r/20240611-apol-ina2xx-fix-v4-2-8df1d2282fc5@axis.com
Signed-off-by: Guenter Roeck <linux@roeck-us.net>

diff --git a/drivers/hwmon/ina2xx.c b/drivers/hwmon/ina2xx.c
index f8b5d972191ee720cb63df00dd2734f249395b3e..9ab4205622e254d6bcf04de9505b703aac9a07e9 100644 (file)
--- a/drivers/hwmon/ina2xx.c
+++ b/drivers/hwmon/ina2xx.c
@@ -73,6 +73,11 @@
 #define INA226_READ_AVG(reg)           (((reg) & INA226_AVG_RD_MASK) >> 9)
 #define INA226_SHIFT_AVG(val)          ((val) << 9)
 
+#define INA226_ALERT_POLARITY_MASK             0x0002
+#define INA226_SHIFT_ALERT_POLARITY(val)       ((val) << 1)
+#define INA226_ALERT_POL_LOW                   0
+#define INA226_ALERT_POL_HIGH                  1
+
 /* bit number of alert functions in Mask/Enable Register */
 #define INA226_SHUNT_OVER_VOLTAGE_BIT  15
 #define INA226_SHUNT_UNDER_VOLTAGE_BIT 14
@@ -178,6 +183,14 @@ static u16 ina226_interval_to_reg(int interval)
        return INA226_SHIFT_AVG(avg_bits);
 }
 
+static int ina2xx_set_alert_polarity(struct ina2xx_data *data,
+                                    unsigned long val)
+{
+       return regmap_update_bits(data->regmap, INA226_MASK_ENABLE,
+                                INA226_ALERT_POLARITY_MASK,
+                                INA226_SHIFT_ALERT_POLARITY(val));
+}
+
 /*
  * Calibration register is set to the best value, which eliminates
  * truncation errors on calculating current register in hardware.
@@ -654,6 +667,25 @@ static int ina2xx_probe(struct i2c_client *client)
        if (ret)
                return dev_err_probe(dev, ret, "failed to enable vs regulator\n");
 
+       if (chip == ina226) {
+               if (of_property_read_bool(dev->of_node, "ti,alert-polarity-active-high")) {
+                       ret = ina2xx_set_alert_polarity(data,
+                                                       INA226_ALERT_POL_HIGH);
+                       if (ret < 0) {
+                               return dev_err_probe(dev, ret,
+                                       "failed to set alert polarity active high\n");
+                       }
+               } else {
+                       /* Set default value i.e active low */
+                       ret = ina2xx_set_alert_polarity(data,
+                                                       INA226_ALERT_POL_LOW);
+                       if (ret < 0) {
+                               return dev_err_probe(dev, ret,
+                                       "failed to set alert polarity active low\n");
+                       }
+               }
+       }
+
        ret = ina2xx_init(data);
        if (ret < 0) {
                dev_err(dev, "error configuring the device: %d\n", ret);