iio: adc: ad7291: convert to device tree

There are no in-tree users of the platform data for this driver, so
remove it and convert the driver to use device tree instead.
Signed-off-by: Michael Auchter <michael.auchter@ni.com>
Link: https://lore.kernel.org/r/20200922144422.542669-1-michael.auchter@ni.comSigned-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

drivers/iio/adc/ad7291.c

@@ -20,8 +20,6 @@
 #include <linux/iio/sysfs.h>
 #include <linux/iio/events.h>
 
-#include <linux/platform_data/ad7291.h>
-
 /*
  * Simplified handling
  *
@@ -465,7 +463,6 @@ static const struct iio_info ad7291_info = {
 static int ad7291_probe(struct i2c_client *client,
 			const struct i2c_device_id *id)
 {
-	struct ad7291_platform_data *pdata = client->dev.platform_data;
 	struct ad7291_chip_info *chip;
 	struct iio_dev *indio_dev;
 	int ret;
@@ -475,16 +472,6 @@ static int ad7291_probe(struct i2c_client *client,
 		return -ENOMEM;
 	chip = iio_priv(indio_dev);
 
-	if (pdata && pdata->use_external_ref) {
-		chip->reg = devm_regulator_get(&client->dev, "vref");
-		if (IS_ERR(chip->reg))
-			return PTR_ERR(chip->reg);
-
-		ret = regulator_enable(chip->reg);
-		if (ret)
-			return ret;
-	}
-
 	mutex_init(&chip->state_lock);
 	/* this is only used for device removal purposes */
 	i2c_set_clientdata(client, indio_dev);
@@ -495,8 +482,21 @@ static int ad7291_probe(struct i2c_client *client,
 			AD7291_T_SENSE_MASK | /* Tsense always enabled */
 			AD7291_ALERT_POLARITY; /* set irq polarity low level */
 
-	if (pdata && pdata->use_external_ref)
+	chip->reg = devm_regulator_get_optional(&client->dev, "vref");
+	if (IS_ERR(chip->reg)) {
+		if (PTR_ERR(chip->reg) != -ENODEV)
+			return PTR_ERR(chip->reg);
+
+		chip->reg = NULL;
+	}
+
+	if (chip->reg) {
+		ret = regulator_enable(chip->reg);
+		if (ret)
+			return ret;
+
 		chip->command |= AD7291_EXT_REF;
+	}
 
 	indio_dev->name = id->name;
 	indio_dev->channels = ad7291_channels;
@@ -567,9 +567,16 @@ static const struct i2c_device_id ad7291_id[] = {
 
 MODULE_DEVICE_TABLE(i2c, ad7291_id);
 
+static const struct of_device_id ad7291_of_match[] = {
+	{ .compatible = "adi,ad7291" },
+	{}
+};
+MODULE_DEVICE_TABLE(of, ad7291_of_match);
+
 static struct i2c_driver ad7291_driver = {
 	.driver = {
 		.name = KBUILD_MODNAME,
+		.of_match_table = ad7291_of_match,
 	},
 	.probe = ad7291_probe,
 	.remove = ad7291_remove,

include/linux/platform_data/ad7291.h

-/* SPDX-License-Identifier: GPL-2.0 */
-#ifndef __IIO_AD7291_H__
-#define __IIO_AD7291_H__
-
-/**
- * struct ad7291_platform_data - AD7291 platform data
- * @use_external_ref: Whether to use an external or internal reference voltage
- */
-struct ad7291_platform_data {
-	bool use_external_ref;
-};
-
-#endif