iio: temp: ltc2983: Use __free(fwnode_handle) and device_for_each_node_scoped()

This use of the new cleanup.h scope based freeing infrastructure allows
us to exit directly from error conditions and in the good path with
the reference obtained from fwnode_find_reference() (which may be an error
pointer) automatically released.

Similarly the _scoped() version of device_for_each_child_node()
removes the need for the manual calling of fwnode_handl_put() in
paths where the code exits the loop early.

Tidy up some unusual indentation in a dev_dbg() whilst here.
Reviewed-by: Nuno Sa <nuno.sa@analog.com>
Link: https://lore.kernel.org/r/20240224123215.161469-2-jic23@kernel.orgSigned-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

drivers/iio/temperature/ltc2983.c

@@ -657,7 +657,6 @@ ltc2983_thermocouple_new(const struct fwnode_handle *child, struct ltc2983_data
 			 const struct ltc2983_sensor *sensor)
 {
 	struct ltc2983_thermocouple *thermo;
-	struct fwnode_handle *ref;
 	u32 oc_current;
 	int ret;
 
@@ -704,7 +703,8 @@ ltc2983_thermocouple_new(const struct fwnode_handle *child, struct ltc2983_data
 		return ERR_PTR(-EINVAL);
 	}
 
-	ref = fwnode_find_reference(child, "adi,cold-junction-handle", 0);
+	struct fwnode_handle *ref __free(fwnode_handle) =
+		fwnode_find_reference(child, "adi,cold-junction-handle", 0);
 	if (IS_ERR(ref)) {
 		ref = NULL;
 	} else {
@@ -715,7 +715,7 @@ ltc2983_thermocouple_new(const struct fwnode_handle *child, struct ltc2983_data
 			 * the error right away.
 			 */
 			dev_err(&st->spi->dev, "Property reg must be given\n");
-			goto fail;
+			return ERR_PTR(ret);
 		}
 	}
 
@@ -726,22 +726,15 @@ ltc2983_thermocouple_new(const struct fwnode_handle *child, struct ltc2983_data
 		thermo->custom = __ltc2983_custom_sensor_new(st, child,
 							     propname, false,
 							     16384, true);
-		if (IS_ERR(thermo->custom)) {
-			ret = PTR_ERR(thermo->custom);
-			goto fail;
-		}
+		if (IS_ERR(thermo->custom))
+			return ERR_CAST(thermo->custom);
 	}
 
 	/* set common parameters */
 	thermo->sensor.fault_handler = ltc2983_thermocouple_fault_handler;
 	thermo->sensor.assign_chan = ltc2983_thermocouple_assign_chan;
 
-	fwnode_handle_put(ref);
 	return &thermo->sensor;
-
-fail:
-	fwnode_handle_put(ref);
-	return ERR_PTR(ret);
 }
 
 static struct ltc2983_sensor *
@@ -751,14 +744,14 @@ ltc2983_rtd_new(const struct fwnode_handle *child, struct ltc2983_data *st,
 	struct ltc2983_rtd *rtd;
 	int ret = 0;
 	struct device *dev = &st->spi->dev;
-	struct fwnode_handle *ref;
 	u32 excitation_current = 0, n_wires = 0;
 
 	rtd = devm_kzalloc(dev, sizeof(*rtd), GFP_KERNEL);
 	if (!rtd)
 		return ERR_PTR(-ENOMEM);
 
-	ref = fwnode_find_reference(child, "adi,rsense-handle", 0);
+	struct fwnode_handle *ref __free(fwnode_handle) =
+		fwnode_find_reference(child, "adi,rsense-handle", 0);
 	if (IS_ERR(ref)) {
 		dev_err(dev, "Property adi,rsense-handle missing or invalid");
 		return ERR_CAST(ref);
@@ -767,7 +760,7 @@ ltc2983_rtd_new(const struct fwnode_handle *child, struct ltc2983_data *st,
 	ret = fwnode_property_read_u32(ref, "reg", &rtd->r_sense_chan);
 	if (ret) {
 		dev_err(dev, "Property reg must be given\n");
-		goto fail;
+		return ERR_PTR(ret);
 	}
 
 	ret = fwnode_property_read_u32(child, "adi,number-of-wires", &n_wires);
@@ -788,8 +781,7 @@ ltc2983_rtd_new(const struct fwnode_handle *child, struct ltc2983_data *st,
 			break;
 		default:
 			dev_err(dev, "Invalid number of wires:%u\n", n_wires);
-			ret = -EINVAL;
-			goto fail;
+			return ERR_PTR(-EINVAL);
 		}
 	}
 
@@ -799,8 +791,7 @@ ltc2983_rtd_new(const struct fwnode_handle *child, struct ltc2983_data *st,
 			if (n_wires == 2 || n_wires == 3) {
 				dev_err(dev,
 					"Rotation not allowed for 2/3 Wire RTDs");
-				ret = -EINVAL;
-				goto fail;
+				return ERR_PTR(-EINVAL);
 			}
 			rtd->sensor_config |= LTC2983_RTD_C_ROTATE(1);
 		} else {
@@ -830,16 +821,14 @@ ltc2983_rtd_new(const struct fwnode_handle *child, struct ltc2983_data *st,
 				"Invalid rsense chann:%d to use in kelvin rsense",
 				rtd->r_sense_chan);
 
-			ret = -EINVAL;
-			goto fail;
+			return ERR_PTR(-EINVAL);
 		}
 
 		if (sensor->chan < min || sensor->chan > max) {
 			dev_err(dev, "Invalid chann:%d for the rtd config",
 				sensor->chan);
 
-			ret = -EINVAL;
-			goto fail;
+			return ERR_PTR(-EINVAL);
 		}
 	} else {
 		/* same as differential case */
@@ -847,8 +836,7 @@ ltc2983_rtd_new(const struct fwnode_handle *child, struct ltc2983_data *st,
 			dev_err(&st->spi->dev,
 				"Invalid chann:%d for RTD", sensor->chan);
 
-			ret = -EINVAL;
-			goto fail;
+			return ERR_PTR(-EINVAL);
 		}
 	}
 
@@ -857,10 +845,8 @@ ltc2983_rtd_new(const struct fwnode_handle *child, struct ltc2983_data *st,
 		rtd->custom = __ltc2983_custom_sensor_new(st, child,
 							  "adi,custom-rtd",
 							  false, 2048, false);
-		if (IS_ERR(rtd->custom)) {
-			ret = PTR_ERR(rtd->custom);
-			goto fail;
-		}
+		if (IS_ERR(rtd->custom))
+			return ERR_CAST(rtd->custom);
 	}
 
 	/* set common parameters */
@@ -902,18 +888,13 @@ ltc2983_rtd_new(const struct fwnode_handle *child, struct ltc2983_data *st,
 			dev_err(&st->spi->dev,
 				"Invalid value for excitation current(%u)",
 				excitation_current);
-			ret = -EINVAL;
-			goto fail;
+			return ERR_PTR(-EINVAL);
 		}
 	}
 
 	fwnode_property_read_u32(child, "adi,rtd-curve", &rtd->rtd_curve);
 
-	fwnode_handle_put(ref);
 	return &rtd->sensor;
-fail:
-	fwnode_handle_put(ref);
-	return ERR_PTR(ret);
 }
 
 static struct ltc2983_sensor *
@@ -922,7 +903,6 @@ ltc2983_thermistor_new(const struct fwnode_handle *child, struct ltc2983_data *s
 {
 	struct ltc2983_thermistor *thermistor;
 	struct device *dev = &st->spi->dev;
-	struct fwnode_handle *ref;
 	u32 excitation_current = 0;
 	int ret = 0;
 
@@ -930,7 +910,8 @@ ltc2983_thermistor_new(const struct fwnode_handle *child, struct ltc2983_data *s
 	if (!thermistor)
 		return ERR_PTR(-ENOMEM);
 
-	ref = fwnode_find_reference(child, "adi,rsense-handle", 0);
+	struct fwnode_handle *ref __free(fwnode_handle) =
+		fwnode_find_reference(child, "adi,rsense-handle", 0);
 	if (IS_ERR(ref)) {
 		dev_err(dev, "Property adi,rsense-handle missing or invalid");
 		return ERR_CAST(ref);
@@ -939,7 +920,7 @@ ltc2983_thermistor_new(const struct fwnode_handle *child, struct ltc2983_data *s
 	ret = fwnode_property_read_u32(ref, "reg", &thermistor->r_sense_chan);
 	if (ret) {
 		dev_err(dev, "rsense channel must be configured...\n");
-		goto fail;
+		return ERR_PTR(ret);
 	}
 
 	if (fwnode_property_read_bool(child, "adi,single-ended")) {
@@ -959,8 +940,7 @@ ltc2983_thermistor_new(const struct fwnode_handle *child, struct ltc2983_data *s
 		dev_err(&st->spi->dev,
 			"Invalid chann:%d for differential thermistor",
 			sensor->chan);
-		ret = -EINVAL;
-		goto fail;
+		return ERR_PTR(-EINVAL);
 	}
 
 	/* check custom sensor */
@@ -979,10 +959,8 @@ ltc2983_thermistor_new(const struct fwnode_handle *child, struct ltc2983_data *s
 								 propname,
 								 steinhart,
 								 64, false);
-		if (IS_ERR(thermistor->custom)) {
-			ret = PTR_ERR(thermistor->custom);
-			goto fail;
-		}
+		if (IS_ERR(thermistor->custom))
+			return ERR_CAST(thermistor->custom);
 	}
 	/* set common parameters */
 	thermistor->sensor.fault_handler = ltc2983_common_fault_handler;
@@ -1006,8 +984,7 @@ ltc2983_thermistor_new(const struct fwnode_handle *child, struct ltc2983_data *s
 			    LTC2983_SENSOR_THERMISTOR_STEINHART) {
 				dev_err(&st->spi->dev,
 					"Auto Range not allowed for custom sensors\n");
-				ret = -EINVAL;
-				goto fail;
+				return ERR_PTR(-EINVAL);
 			}
 			thermistor->excitation_current = 0x0c;
 			break;
@@ -1048,16 +1025,11 @@ ltc2983_thermistor_new(const struct fwnode_handle *child, struct ltc2983_data *s
 			dev_err(&st->spi->dev,
 				"Invalid value for excitation current(%u)",
 				excitation_current);
-			ret = -EINVAL;
-			goto fail;
+			return ERR_PTR(-EINVAL);
 		}
 	}
 
-	fwnode_handle_put(ref);
 	return &thermistor->sensor;
-fail:
-	fwnode_handle_put(ref);
-	return ERR_PTR(ret);
 }
 
 static struct ltc2983_sensor *
@@ -1350,8 +1322,7 @@ static irqreturn_t ltc2983_irq_handler(int irq, void *data)
 static int ltc2983_parse_fw(struct ltc2983_data *st)
 {
 	struct device *dev = &st->spi->dev;
-	struct fwnode_handle *child;
-	int ret = 0, chan = 0, channel_avail_mask = 0;
+	int ret, chan = 0, channel_avail_mask = 0;
 
 	device_property_read_u32(dev, "adi,mux-delay-config-us", &st->mux_delay_config);
 
@@ -1369,38 +1340,35 @@ static int ltc2983_parse_fw(struct ltc2983_data *st)
 		return -ENOMEM;
 
 	st->iio_channels = st->num_channels;
-	device_for_each_child_node(dev, child) {
+	device_for_each_child_node_scoped(dev, child) {
 		struct ltc2983_sensor sensor;
 
 		ret = fwnode_property_read_u32(child, "reg", &sensor.chan);
-		if (ret) {
-			dev_err(dev, "reg property must given for child nodes\n");
-			goto put_child;
-		}
+		if (ret)
+			return dev_err_probe(dev, ret,
+				"reg property must given for child nodes\n");
 
 		/* check if we have a valid channel */
 		if (sensor.chan < LTC2983_MIN_CHANNELS_NR ||
-		    sensor.chan > st->info->max_channels_nr) {
-			ret = -EINVAL;
-			dev_err(dev, "chan:%d must be from %u to %u\n", sensor.chan,
-				LTC2983_MIN_CHANNELS_NR, st->info->max_channels_nr);
-			goto put_child;
-		} else if (channel_avail_mask & BIT(sensor.chan)) {
-			ret = -EINVAL;
-			dev_err(dev, "chan:%d already in use\n", sensor.chan);
-			goto put_child;
-		}
+		    sensor.chan > st->info->max_channels_nr)
+			return dev_err_probe(dev, -EINVAL,
+					     "chan:%d must be from %u to %u\n",
+					     sensor.chan,
+					     LTC2983_MIN_CHANNELS_NR,
+					     st->info->max_channels_nr);
+
+		if (channel_avail_mask & BIT(sensor.chan))
+			return dev_err_probe(dev, -EINVAL,
+					     "chan:%d already in use\n",
+					     sensor.chan);
 
 		ret = fwnode_property_read_u32(child, "adi,sensor-type", &sensor.type);
-		if (ret) {
-			dev_err(dev,
+		if (ret)
+			return dev_err_probe(dev, ret,
 				"adi,sensor-type property must given for child nodes\n");
-			goto put_child;
-		}
 
 		dev_dbg(dev, "Create new sensor, type %u, chann %u",
-								sensor.type,
-								sensor.chan);
+			sensor.type, sensor.chan);
 
 		if (sensor.type >= LTC2983_SENSOR_THERMOCOUPLE &&
 		    sensor.type <= LTC2983_SENSOR_THERMOCOUPLE_CUSTOM) {
@@ -1427,17 +1395,15 @@ static int ltc2983_parse_fw(struct ltc2983_data *st)
 			   sensor.type == LTC2983_SENSOR_ACTIVE_TEMP) {
 			st->sensors[chan] = ltc2983_temp_new(child, st, &sensor);
 		} else {
-			dev_err(dev, "Unknown sensor type %d\n", sensor.type);
-			ret = -EINVAL;
-			goto put_child;
+			return dev_err_probe(dev, -EINVAL,
+					     "Unknown sensor type %d\n",
+					     sensor.type);
 		}
 
-		if (IS_ERR(st->sensors[chan])) {
-			dev_err(dev, "Failed to create sensor %ld",
-				PTR_ERR(st->sensors[chan]));
-			ret = PTR_ERR(st->sensors[chan]);
-			goto put_child;
-		}
+		if (IS_ERR(st->sensors[chan]))
+			return dev_err_probe(dev, PTR_ERR(st->sensors[chan]),
+					     "Failed to create sensor\n");
+
 		/* set generic sensor parameters */
 		st->sensors[chan]->chan = sensor.chan;
 		st->sensors[chan]->type = sensor.type;
@@ -1447,9 +1413,6 @@ static int ltc2983_parse_fw(struct ltc2983_data *st)
 	}
 
 	return 0;
-put_child:
-	fwnode_handle_put(child);
-	return ret;
 }
 
 static int ltc2983_eeprom_cmd(struct ltc2983_data *st, unsigned int cmd,