iio: adc: rn5t618: Add iio map

Add iio map to allow power driver to read out values as a consumer.
This approach does not block later addition of devicetree support
which would be helpful if there is an in-kernel consumer for AIN0/1.
Signed-off-by: Andreas Kemnade <andreas@kemnade.info>
Acked-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>
Signed-off-by: Sebastian Reichel <sebastian.reichel@collabora.com>

drivers/iio/adc/rn5t618-adc.c

@@ -16,6 +16,8 @@
 #include <linux/completion.h>
 #include <linux/regmap.h>
 #include <linux/iio/iio.h>
+#include <linux/iio/driver.h>
+#include <linux/iio/machine.h>
 #include <linux/slab.h>
 
 #define RN5T618_ADC_CONVERSION_TIMEOUT   (msecs_to_jiffies(500))
@@ -189,6 +191,19 @@ static const struct iio_chan_spec rn5t618_adc_iio_channels[] = {
 	RN5T618_ADC_CHANNEL(AIN0, IIO_VOLTAGE, "AIN0")
 };
 
+static struct iio_map rn5t618_maps[] = {
+	IIO_MAP("VADP", "rn5t618-power", "vadp"),
+	IIO_MAP("VUSB", "rn5t618-power", "vusb"),
+	{ /* sentinel */ }
+};
+
+static void unregister_map(void *data)
+{
+	struct iio_dev *iio_dev = (struct iio_dev *) data;
+
+	iio_map_array_unregister(iio_dev);
+}
+
 static int rn5t618_adc_probe(struct platform_device *pdev)
 {
 	int ret;
@@ -239,6 +254,14 @@ static int rn5t618_adc_probe(struct platform_device *pdev)
 		return ret;
 	}
 
+	ret = iio_map_array_register(iio_dev, rn5t618_maps);
+	if (ret < 0)
+		return ret;
+
+	ret = devm_add_action_or_reset(adc->dev, unregister_map, iio_dev);
+	if (ret < 0)
+		return ret;
+
 	return devm_iio_device_register(adc->dev, iio_dev);
 }