From: Guenter Roeck <linux@roeck-us.net>
Date: Sun, 31 Aug 2025 16:39:53 +0000 (-0700)
Subject: hwmon: (ina238) Only configure calibration and shunt registers if needed
X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=d153106bd4fd63eb8d3557277a3d4ee5dbbed3b0;p=users%2Fhch%2Fmisc.git

hwmon: (ina238) Only configure calibration and shunt registers if needed

Prepare for supporting chips with internal shunt resistor by only setting
calibration and shunt resistor registers if no current LSB is configured.

Do not display a log message during probe if a chip does not have shunt
and gain registers since those would otherwise display 0, and a message
just indicating that the driver was loaded would be just noise.

Reviewed-by: Chris Packham <chris.packham@alliedtelesis.co.nz>
Tested-by: Chris Packham <chris.packham@alliedtelesis.co.nz> # INA780
Signed-off-by: Guenter Roeck <linux@roeck-us.net>
---

diff --git a/drivers/hwmon/ina238.c b/drivers/hwmon/ina238.c
index 24e396c69ae2..da5b43184dd1 100644
--- a/drivers/hwmon/ina238.c
+++ b/drivers/hwmon/ina238.c
@@ -745,32 +745,48 @@ static int ina238_probe(struct i2c_client *client)
 		return PTR_ERR(data->regmap);
 	}
 
-	/* load shunt value */
-	if (device_property_read_u32(dev, "shunt-resistor", &data->rshunt) < 0)
-		data->rshunt = INA238_RSHUNT_DEFAULT;
-	if (data->rshunt == 0) {
-		dev_err(dev, "invalid shunt resister value %u\n", data->rshunt);
-		return -EINVAL;
-	}
-
-	/* load shunt gain value */
-	if (device_property_read_u32(dev, "ti,shunt-gain", &data->gain) < 0)
-		data->gain = 4; /* Default of ADCRANGE = 0 */
-	if (data->gain != 1 && data->gain != 2 && data->gain != 4) {
-		dev_err(dev, "invalid shunt gain value %u\n", data->gain);
-		return -EINVAL;
-	}
-
 	/* Setup CONFIG register */
 	config = data->config->config_default;
-	if (chip == sq52206) {
-		if (data->gain == 1)
-			config |= SQ52206_CONFIG_ADCRANGE_HIGH; /* ADCRANGE = 10/11 is /1 */
-		else if (data->gain == 2)
-			config |= SQ52206_CONFIG_ADCRANGE_LOW; /* ADCRANGE = 01 is /2 */
-	} else if (data->gain == 1) {
-		config |= INA238_CONFIG_ADCRANGE; /* ADCRANGE = 1 is /1 */
+	if (data->config->current_lsb) {
+		data->voltage_lsb[0] = INA238_SHUNT_VOLTAGE_LSB;
+		data->current_lsb = data->config->current_lsb;
+	} else {
+		/* load shunt value */
+		if (device_property_read_u32(dev, "shunt-resistor", &data->rshunt) < 0)
+			data->rshunt = INA238_RSHUNT_DEFAULT;
+		if (data->rshunt == 0) {
+			dev_err(dev, "invalid shunt resister value %u\n", data->rshunt);
+			return -EINVAL;
+		}
+
+		/* load shunt gain value */
+		if (device_property_read_u32(dev, "ti,shunt-gain", &data->gain) < 0)
+			data->gain = 4;	/* Default of ADCRANGE = 0 */
+		if (data->gain != 1 && data->gain != 2 && data->gain != 4) {
+			dev_err(dev, "invalid shunt gain value %u\n", data->gain);
+			return -EINVAL;
+		}
+
+		/* Setup SHUNT_CALIBRATION register with fixed value */
+		ret = regmap_write(data->regmap, INA238_SHUNT_CALIBRATION,
+				   INA238_CALIBRATION_VALUE);
+		if (ret < 0) {
+			dev_err(dev, "error configuring the device: %d\n", ret);
+			return -ENODEV;
+		}
+		if (chip == sq52206) {
+			if (data->gain == 1)		/* ADCRANGE = 10/11 is /1 */
+				config |= SQ52206_CONFIG_ADCRANGE_HIGH;
+			else if (data->gain == 2)	/* ADCRANGE = 01 is /2 */
+				config |= SQ52206_CONFIG_ADCRANGE_LOW;
+		} else if (data->gain == 1) {		/* ADCRANGE = 1 is /1 */
+			config |= INA238_CONFIG_ADCRANGE;
+		}
+		data->voltage_lsb[0] = INA238_SHUNT_VOLTAGE_LSB * data->gain / 4;
+		data->current_lsb = DIV_U64_ROUND_CLOSEST(250ULL * INA238_FIXED_SHUNT * data->gain,
+							  data->rshunt);
 	}
+
 	ret = regmap_write(data->regmap, INA238_CONFIG, config);
 	if (ret < 0) {
 		dev_err(dev, "error configuring the device: %d\n", ret);
@@ -785,14 +801,6 @@ static int ina238_probe(struct i2c_client *client)
 		return -ENODEV;
 	}
 
-	/* Setup SHUNT_CALIBRATION register with fixed value */
-	ret = regmap_write(data->regmap, INA238_SHUNT_CALIBRATION,
-			   INA238_CALIBRATION_VALUE);
-	if (ret < 0) {
-		dev_err(dev, "error configuring the device: %d\n", ret);
-		return -ENODEV;
-	}
-
 	/* Setup alert/alarm configuration */
 	config = INA238_DIAG_ALERT_DEFAULT;
 	if (device_property_read_bool(dev, "ti,alert-polarity-active-high"))
@@ -804,15 +812,8 @@ static int ina238_probe(struct i2c_client *client)
 		return -ENODEV;
 	}
 
-	data->voltage_lsb[0] = INA238_SHUNT_VOLTAGE_LSB * data->gain / 4;
 	data->voltage_lsb[1] = data->config->bus_voltage_lsb;
 
-	if (data->config->current_lsb)
-		data->current_lsb = data->config->current_lsb;
-	else
-		data->current_lsb = DIV_U64_ROUND_CLOSEST(250ULL * INA238_FIXED_SHUNT * data->gain,
-							  data->rshunt);
-
 	data->power_lsb = DIV_ROUND_CLOSEST(data->current_lsb *
 					    data->config->power_calculate_factor,
 					    100);
@@ -824,8 +825,9 @@ static int ina238_probe(struct i2c_client *client)
 	if (IS_ERR(hwmon_dev))
 		return PTR_ERR(hwmon_dev);
 
-	dev_info(dev, "power monitor %s (Rshunt = %u uOhm, gain = %u)\n",
-		 client->name, data->rshunt, data->gain);
+	if (data->rshunt)
+		dev_info(dev, "power monitor %s (Rshunt = %u uOhm, gain = %u)\n",
+			 client->name, data->rshunt, data->gain);
 
 	return 0;
 }