[PATCH v4 2/2] hwmon: (ina2xx) Add device tree support to pass alert polarity

Amna Waseem
2024-06-11T09:36:33Z

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>
---
drivers/hwmon/ina2xx.c | 32 ++++++++++++++++++++++++++++++++
1 file changed, 32 insertions(+)

diff --git a/drivers/hwmon/ina2xx.c b/drivers/hwmon/ina2xx.c
index d8415d1f21fc..f26ba479bf5c 100644
--- 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.
@@ -659,6 +672,25 @@ 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);

--
2.30.2