iio: adc: ad7791: convert to device-managed functions

With the devm_ad_sd_setup_buffer_and_trigger() helper, it's a bit easier
now to convert the probe of the AD7791 driver to use device-managed
functions.

Only the regulator disable requires a devm_add_action_or_reset() callback.

This change does that, cleaning up the driver a bit.
Signed-off-by: Alexandru Ardelean <aardelean@deviqon.com>
Link: https://lore.kernel.org/r/20210513120752.90074-8-aardelean@deviqon.comSigned-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

drivers/iio/adc/ad7791.c

@@ -394,6 +394,11 @@ static int ad7791_setup(struct ad7791_state *st,
 		st->mode);
 }
 
+static void ad7791_reg_disable(void *reg)
+{
+	regulator_disable(reg);
+}
+
 static int ad7791_probe(struct spi_device *spi)
 {
 	struct ad7791_platform_data *pdata = spi->dev.platform_data;
@@ -420,11 +425,13 @@ static int ad7791_probe(struct spi_device *spi)
 	if (ret)
 		return ret;
 
+	ret = devm_add_action_or_reset(&spi->dev, ad7791_reg_disable, st->reg);
+	if (ret)
+		return ret;
+
 	st->info = &ad7791_chip_infos[spi_get_device_id(spi)->driver_data];
 	ad_sd_init(&st->sd, indio_dev, spi, &ad7791_sigma_delta_info);
 
-	spi_set_drvdata(spi, indio_dev);
-
 	indio_dev->name = spi_get_device_id(spi)->name;
 	indio_dev->modes = INDIO_DIRECT_MODE;
 	indio_dev->channels = st->info->channels;
@@ -434,39 +441,15 @@ static int ad7791_probe(struct spi_device *spi)
 	else
 		indio_dev->info = &ad7791_no_filter_info;
 
-	ret = ad_sd_setup_buffer_and_trigger(indio_dev);
+	ret = devm_ad_sd_setup_buffer_and_trigger(&spi->dev, indio_dev);
 	if (ret)
-		goto error_disable_reg;
+		return ret;
 
 	ret = ad7791_setup(st, pdata);
 	if (ret)
-		goto error_remove_trigger;
-
-	ret = iio_device_register(indio_dev);
-	if (ret)
-		goto error_remove_trigger;
-
-	return 0;
-
-error_remove_trigger:
-	ad_sd_cleanup_buffer_and_trigger(indio_dev);
-error_disable_reg:
-	regulator_disable(st->reg);
-
-	return ret;
-}
-
-static int ad7791_remove(struct spi_device *spi)
-{
-	struct iio_dev *indio_dev = spi_get_drvdata(spi);
-	struct ad7791_state *st = iio_priv(indio_dev);
-
-	iio_device_unregister(indio_dev);
-	ad_sd_cleanup_buffer_and_trigger(indio_dev);
-
-	regulator_disable(st->reg);
+		return ret;
 
-	return 0;
+	return devm_iio_device_register(&spi->dev, indio_dev);
 }
 
 static const struct spi_device_id ad7791_spi_ids[] = {
@@ -484,7 +467,6 @@ static struct spi_driver ad7791_driver = {
 		.name	= "ad7791",
 	},
 	.probe		= ad7791_probe,
-	.remove		= ad7791_remove,
 	.id_table	= ad7791_spi_ids,
 };
 module_spi_driver(ad7791_driver);