iio: temperature: ltc2983: Make use of device properties

Convert the module to be property provider agnostic and allow
it to be used on non-OF platforms.

The conversion slightly changes the logic behind property reading for
the configuration values. Original code allocates just as much memory
as needed. Then for each separate 32- or 64-bit value it reads it from
the property and converts to a raw one which will be fed to the sensor.
In the new code we allocate the amount of memory needed to retrieve all
values at once from the property and then convert them as required.

Signed-off-by: Andy Shevchenko <[e-mail]>
Reviewed-by: Nuno Sá <[e-mail]>
Tested-by: Nuno Sá <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Jonathan Cameron <[e-mail]>

drivers/iio/temperature/ltc2983.c

···
 #include <linux/iio/iio.h>
 #include <linux/interrupt.h>
 #include <linux/list.h>
+#include <linux/mod_devicetable.h>
 #include <linux/module.h>
-#include <linux/of_gpio.h>
+#include <linux/property.h>
 #include <linux/regmap.h>
 #include <linux/spi/spi.h>
+
+#include <asm/byteorder.h>
+#include <asm/unaligned.h>
 
 /* register map */
 #define LTC2983_STATUS_REG			0x0000
···
 
 struct ltc2983_custom_sensor {
 	/* raw table sensor data */
-	u8 *table;
+	void *table;
 	size_t size;
 	/* address offset */
 	s8 offset;
···
 	return regmap_bulk_write(st->regmap, reg, custom->table, custom->size);
 }
 
-static struct ltc2983_custom_sensor *__ltc2983_custom_sensor_new(
-						struct ltc2983_data *st,
-						const struct device_node *np,
-						const char *propname,
-						const bool is_steinhart,
-						const u32 resolution,
-						const bool has_signed)
+static struct ltc2983_custom_sensor *
+__ltc2983_custom_sensor_new(struct ltc2983_data *st, const struct fwnode_handle *fn,
+			    const char *propname, const bool is_steinhart,
+			    const u32 resolution, const bool has_signed)
 {
 	struct ltc2983_custom_sensor *new_custom;
-	u8 index, n_entries, tbl = 0;
 	struct device *dev = &st->spi->dev;
 	/*
 	 * For custom steinhart, the full u32 is taken. For all the others
 	 * the MSB is discarded.
 	 */
 	const u8 n_size = is_steinhart ? 4 : 3;
-	const u8 e_size = is_steinhart ? sizeof(u32) : sizeof(u64);
+	u8 index, n_entries;
+	int ret;
 
-	n_entries = of_property_count_elems_of_size(np, propname, e_size);
+	if (is_steinhart)
+		n_entries = fwnode_property_count_u32(fn, propname);
+	else
+		n_entries = fwnode_property_count_u64(fn, propname);
 	/* n_entries must be an even number */
 	if (!n_entries || (n_entries % 2) != 0) {
 		dev_err(dev, "Number of entries either 0 or not even\n");
···
 	}
 
 	/* allocate the table */
-	new_custom->table = devm_kzalloc(dev, new_custom->size, GFP_KERNEL);
+	if (is_steinhart)
+		new_custom->table = devm_kcalloc(dev, n_entries, sizeof(u32), GFP_KERNEL);
+	else
+		new_custom->table = devm_kcalloc(dev, n_entries, sizeof(u64), GFP_KERNEL);
 	if (!new_custom->table)
 		return ERR_PTR(-ENOMEM);
 
-	for (index = 0; index < n_entries; index++) {
-		u64 temp = 0, j;
-		/*
-		 * Steinhart sensors are configured with raw values in the
-		 * devicetree. For the other sensors we must convert the
-		 * value to raw. The odd index's correspond to temperarures
-		 * and always have 1/1024 of resolution. Temperatures also
-		 * come in kelvin, so signed values is not possible
-		 */
-		if (!is_steinhart) {
-			of_property_read_u64_index(np, propname, index, &temp);
+	/*
+	 * Steinhart sensors are configured with raw values in the firmware
+	 * node. For the other sensors we must convert the value to raw.
+	 * The odd index's correspond to temperatures and always have 1/1024
+	 * of resolution. Temperatures also come in Kelvin, so signed values
+	 * are not possible.
+	 */
+	if (is_steinhart) {
+		ret = fwnode_property_read_u32_array(fn, propname, new_custom->table, n_entries);
+		if (ret < 0)
+			return ERR_PTR(ret);
+
+		cpu_to_be32_array(new_custom->table, new_custom->table, n_entries);
+	} else {
+		ret = fwnode_property_read_u64_array(fn, propname, new_custom->table, n_entries);
+		if (ret < 0)
+			return ERR_PTR(ret);
+
+		for (index = 0; index < n_entries; index++) {
+			u64 temp = ((u64 *)new_custom->table)[index];
 
 			if ((index % 2) != 0)
 				temp = __convert_to_raw(temp, 1024);
···
 				temp = __convert_to_raw_sign(temp, resolution);
 			else
 				temp = __convert_to_raw(temp, resolution);
-		} else {
-			u32 t32;
 
-			of_property_read_u32_index(np, propname, index, &t32);
-			temp = t32;
+			put_unaligned_be24(temp, new_custom->table + index * 3);
 		}
-
-		for (j = 0; j < n_size; j++)
-			new_custom->table[tbl++] =
-				temp >> (8 * (n_size - j - 1));
 	}
 
 	new_custom->is_steinhart = is_steinhart;
···
 	return __ltc2983_chan_assign_common(st, sensor, chan_val);
 }
 
-static struct ltc2983_sensor *ltc2983_thermocouple_new(
-					const struct device_node *child,
-					struct ltc2983_data *st,
-					const struct ltc2983_sensor *sensor)
+static struct ltc2983_sensor *
+ltc2983_thermocouple_new(const struct fwnode_handle *child, struct ltc2983_data *st,
+			 const struct ltc2983_sensor *sensor)
 {
 	struct ltc2983_thermocouple *thermo;
-	struct device_node *phandle;
+	struct fwnode_handle *ref;
 	u32 oc_current;
 	int ret;
 
···
 	if (!thermo)
 		return ERR_PTR(-ENOMEM);
 
-	if (of_property_read_bool(child, "adi,single-ended"))
+	if (fwnode_property_read_bool(child, "adi,single-ended"))
 		thermo->sensor_config = LTC2983_THERMOCOUPLE_SGL(1);
 
-	ret = of_property_read_u32(child, "adi,sensor-oc-current-microamp",
-				   &oc_current);
+	ret = fwnode_property_read_u32(child, "adi,sensor-oc-current-microamp", &oc_current);
 	if (!ret) {
 		switch (oc_current) {
 		case 10:
···
 		return ERR_PTR(-EINVAL);
 	}
 
-	phandle = of_parse_phandle(child, "adi,cold-junction-handle", 0);
-	if (phandle) {
-		ret = of_property_read_u32(phandle, "reg",
-					   &thermo->cold_junction_chan);
+	ref = fwnode_find_reference(child, "adi,cold-junction-handle", 0);
+	if (IS_ERR(ref)) {
+		ref = NULL;
+	} else {
+		ret = fwnode_property_read_u32(ref, "reg", &thermo->cold_junction_chan);
 		if (ret) {
 			/*
 			 * This would be catched later but we can just return
···
 	thermo->sensor.fault_handler = ltc2983_thermocouple_fault_handler;
 	thermo->sensor.assign_chan = ltc2983_thermocouple_assign_chan;
 
-	of_node_put(phandle);
+	fwnode_handle_put(ref);
 	return &thermo->sensor;
 
 fail:
-	of_node_put(phandle);
+	fwnode_handle_put(ref);
 	return ERR_PTR(ret);
 }
 
-static struct ltc2983_sensor *ltc2983_rtd_new(const struct device_node *child,
-					  struct ltc2983_data *st,
-					  const struct ltc2983_sensor *sensor)
+static struct ltc2983_sensor *
+ltc2983_rtd_new(const struct fwnode_handle *child, struct ltc2983_data *st,
+		const struct ltc2983_sensor *sensor)
 {
 	struct ltc2983_rtd *rtd;
 	int ret = 0;
 	struct device *dev = &st->spi->dev;
-	struct device_node *phandle;
+	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);
 
-	phandle = of_parse_phandle(child, "adi,rsense-handle", 0);
-	if (!phandle) {
+	ref = fwnode_find_reference(child, "adi,rsense-handle", 0);
+	if (IS_ERR(ref)) {
 		dev_err(dev, "Property adi,rsense-handle missing or invalid");
-		return ERR_PTR(-EINVAL);
+		return ERR_CAST(ref);
 	}
 
-	ret = of_property_read_u32(phandle, "reg", &rtd->r_sense_chan);
+	ret = fwnode_property_read_u32(ref, "reg", &rtd->r_sense_chan);
 	if (ret) {
 		dev_err(dev, "Property reg must be given\n");
 		goto fail;
 	}
 
-	ret = of_property_read_u32(child, "adi,number-of-wires", &n_wires);
+	ret = fwnode_property_read_u32(child, "adi,number-of-wires", &n_wires);
 	if (!ret) {
 		switch (n_wires) {
 		case 2:
···
 		}
 	}
 
-	if (of_property_read_bool(child, "adi,rsense-share")) {
+	if (fwnode_property_read_bool(child, "adi,rsense-share")) {
 		/* Current rotation is only available with rsense sharing */
-		if (of_property_read_bool(child, "adi,current-rotate")) {
+		if (fwnode_property_read_bool(child, "adi,current-rotate")) {
 			if (n_wires == 2 || n_wires == 3) {
 				dev_err(dev,
 					"Rotation not allowed for 2/3 Wire RTDs");
···
 	rtd->sensor.fault_handler = ltc2983_common_fault_handler;
 	rtd->sensor.assign_chan = ltc2983_rtd_assign_chan;
 
-	ret = of_property_read_u32(child, "adi,excitation-current-microamp",
-				   &excitation_current);
+	ret = fwnode_property_read_u32(child, "adi,excitation-current-microamp",
+				       &excitation_current);
 	if (ret) {
 		/* default to 5uA */
 		rtd->excitation_current = 1;
···
 		}
 	}
 
-	of_property_read_u32(child, "adi,rtd-curve", &rtd->rtd_curve);
+	fwnode_property_read_u32(child, "adi,rtd-curve", &rtd->rtd_curve);
 
-	of_node_put(phandle);
+	fwnode_handle_put(ref);
 	return &rtd->sensor;
 fail:
-	of_node_put(phandle);
+	fwnode_handle_put(ref);
 	return ERR_PTR(ret);
 }
 
-static struct ltc2983_sensor *ltc2983_thermistor_new(
-					const struct device_node *child,
-					struct ltc2983_data *st,
-					const struct ltc2983_sensor *sensor)
+static struct ltc2983_sensor *
+ltc2983_thermistor_new(const struct fwnode_handle *child, struct ltc2983_data *st,
+		       const struct ltc2983_sensor *sensor)
 {
 	struct ltc2983_thermistor *thermistor;
 	struct device *dev = &st->spi->dev;
-	struct device_node *phandle;
+	struct fwnode_handle *ref;
 	u32 excitation_current = 0;
 	int ret = 0;
 
···
 	if (!thermistor)
 		return ERR_PTR(-ENOMEM);
 
-	phandle = of_parse_phandle(child, "adi,rsense-handle", 0);
-	if (!phandle) {
+	ref = fwnode_find_reference(child, "adi,rsense-handle", 0);
+	if (IS_ERR(ref)) {
 		dev_err(dev, "Property adi,rsense-handle missing or invalid");
-		return ERR_PTR(-EINVAL);
+		return ERR_CAST(ref);
 	}
 
-	ret = of_property_read_u32(phandle, "reg", &thermistor->r_sense_chan);
+	ret = fwnode_property_read_u32(ref, "reg", &thermistor->r_sense_chan);
 	if (ret) {
 		dev_err(dev, "rsense channel must be configured...\n");
 		goto fail;
 	}
 
-	if (of_property_read_bool(child, "adi,single-ended")) {
+	if (fwnode_property_read_bool(child, "adi,single-ended")) {
 		thermistor->sensor_config = LTC2983_THERMISTOR_SGL(1);
-	} else if (of_property_read_bool(child, "adi,rsense-share")) {
+	} else if (fwnode_property_read_bool(child, "adi,rsense-share")) {
 		/* rotation is only possible if sharing rsense */
-		if (of_property_read_bool(child, "adi,current-rotate"))
+		if (fwnode_property_read_bool(child, "adi,current-rotate"))
 			thermistor->sensor_config =
 						LTC2983_THERMISTOR_C_ROTATE(1);
 		else
···
 	thermistor->sensor.fault_handler = ltc2983_common_fault_handler;
 	thermistor->sensor.assign_chan = ltc2983_thermistor_assign_chan;
 
-	ret = of_property_read_u32(child, "adi,excitation-current-nanoamp",
-				   &excitation_current);
+	ret = fwnode_property_read_u32(child, "adi,excitation-current-nanoamp",
+				       &excitation_current);
 	if (ret) {
 		/* Auto range is not allowed for custom sensors */
 		if (sensor->type >= LTC2983_SENSOR_THERMISTOR_STEINHART)
···
 		}
 	}
 
-	of_node_put(phandle);
+	fwnode_handle_put(ref);
 	return &thermistor->sensor;
 fail:
-	of_node_put(phandle);
+	fwnode_handle_put(ref);
 	return ERR_PTR(ret);
 }
 
-static struct ltc2983_sensor *ltc2983_diode_new(
-					const struct device_node *child,
-					const struct ltc2983_data *st,
-					const struct ltc2983_sensor *sensor)
+static struct ltc2983_sensor *
+ltc2983_diode_new(const struct fwnode_handle *child, const struct ltc2983_data *st,
+		  const struct ltc2983_sensor *sensor)
 {
 	struct ltc2983_diode *diode;
 	u32 temp = 0, excitation_current = 0;
···
 	if (!diode)
 		return ERR_PTR(-ENOMEM);
 
-	if (of_property_read_bool(child, "adi,single-ended"))
+	if (fwnode_property_read_bool(child, "adi,single-ended"))
 		diode->sensor_config = LTC2983_DIODE_SGL(1);
 
-	if (of_property_read_bool(child, "adi,three-conversion-cycles"))
+	if (fwnode_property_read_bool(child, "adi,three-conversion-cycles"))
 		diode->sensor_config |= LTC2983_DIODE_3_CONV_CYCLE(1);
 
-	if (of_property_read_bool(child, "adi,average-on"))
+	if (fwnode_property_read_bool(child, "adi,average-on"))
 		diode->sensor_config |= LTC2983_DIODE_AVERAGE_ON(1);
 
 	/* validate channel index */
···
 	diode->sensor.fault_handler = ltc2983_common_fault_handler;
 	diode->sensor.assign_chan = ltc2983_diode_assign_chan;
 
-	ret = of_property_read_u32(child, "adi,excitation-current-microamp",
-				   &excitation_current);
+	ret = fwnode_property_read_u32(child, "adi,excitation-current-microamp",
+				       &excitation_current);
 	if (!ret) {
 		switch (excitation_current) {
 		case 10:
···
 		}
 	}
 
-	of_property_read_u32(child, "adi,ideal-factor-value", &temp);
+	fwnode_property_read_u32(child, "adi,ideal-factor-value", &temp);
 
 	/* 2^20 resolution */
 	diode->ideal_factor_value = __convert_to_raw(temp, 1048576);
···
 	return &diode->sensor;
 }
 
-static struct ltc2983_sensor *ltc2983_r_sense_new(struct device_node *child,
+static struct ltc2983_sensor *ltc2983_r_sense_new(struct fwnode_handle *child,
 					struct ltc2983_data *st,
 					const struct ltc2983_sensor *sensor)
 {
···
 		return ERR_PTR(-EINVAL);
 	}
 
-	ret = of_property_read_u32(child, "adi,rsense-val-milli-ohms", &temp);
+	ret = fwnode_property_read_u32(child, "adi,rsense-val-milli-ohms", &temp);
 	if (ret) {
 		dev_err(&st->spi->dev, "Property adi,rsense-val-milli-ohms missing\n");
 		return ERR_PTR(-EINVAL);
···
 	return &rsense->sensor;
 }
 
-static struct ltc2983_sensor *ltc2983_adc_new(struct device_node *child,
+static struct ltc2983_sensor *ltc2983_adc_new(struct fwnode_handle *child,
 					 struct ltc2983_data *st,
 					 const struct ltc2983_sensor *sensor)
 {
···
 	if (!adc)
 		return ERR_PTR(-ENOMEM);
 
-	if (of_property_read_bool(child, "adi,single-ended"))
+	if (fwnode_property_read_bool(child, "adi,single-ended"))
 		adc->single_ended = true;
 
 	if (!adc->single_ended &&
···
 
 static int ltc2983_parse_dt(struct ltc2983_data *st)
 {
-	struct device_node *child;
 	struct device *dev = &st->spi->dev;
+	struct fwnode_handle *child;
 	int ret = 0, chan = 0, channel_avail_mask = 0;
 
-	of_property_read_u32(dev->of_node, "adi,mux-delay-config-us",
-			     &st->mux_delay_config);
+	device_property_read_u32(dev, "adi,mux-delay-config-us", &st->mux_delay_config);
 
-	of_property_read_u32(dev->of_node, "adi,filter-notch-freq",
-			     &st->filter_notch_freq);
+	device_property_read_u32(dev, "adi,filter-notch-freq", &st->filter_notch_freq);
 
-	st->num_channels = of_get_available_child_count(dev->of_node);
+	st->num_channels = device_get_child_node_count(dev);
 	if (!st->num_channels) {
 		dev_err(&st->spi->dev, "At least one channel must be given!");
 		return -EINVAL;
···
 		return -ENOMEM;
 
 	st->iio_channels = st->num_channels;
-	for_each_available_child_of_node(dev->of_node, child) {
+	device_for_each_child_node(dev, child) {
 		struct ltc2983_sensor sensor;
 
-		ret = of_property_read_u32(child, "reg", &sensor.chan);
+		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;
···
 			goto put_child;
 		}
 
-		ret = of_property_read_u32(child, "adi,sensor-type",
-					       &sensor.type);
+		ret = fwnode_property_read_u32(child, "adi,sensor-type", &sensor.type);
 		if (ret) {
 			dev_err(dev,
 				"adi,sensor-type property must given for child nodes\n");
···
 
 	return 0;
 put_child:
-	of_node_put(child);
+	fwnode_handle_put(child);
 	return ret;
 }