iio: light: gp2ap002: Take runtime PM reference on light read

The light sensor needs the regulators to be enabled which means
the runtime PM needs to be on.  This only happened when the
proximity part of the chip was enabled.

As fallout from this change, only report changes to the prox
state in the interrupt handler when it is explicitly enabled.

Fixes: 97d642e2 ("iio: light: Add a driver for Sharp GP2AP002x00F")
Signed-off-by: Jonathan Bakker <xc-racer2@live.ca>
Reviewed-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

drivers/iio/light/gp2ap002.c

@@ -158,6 +158,9 @@ static irqreturn_t gp2ap002_prox_irq(int irq, void *d)
 	int val;
 	int ret;
 
+	if (!gp2ap002->enabled)
+		goto err_retrig;
+
 	ret = regmap_read(gp2ap002->map, GP2AP002_PROX, &val);
 	if (ret) {
 		dev_err(gp2ap002->dev, "error reading proximity\n");
@@ -247,6 +250,8 @@ static int gp2ap002_read_raw(struct iio_dev *indio_dev,
 	struct gp2ap002 *gp2ap002 = iio_priv(indio_dev);
 	int ret;
 
+	pm_runtime_get_sync(gp2ap002->dev);
+
 	switch (mask) {
 	case IIO_CHAN_INFO_RAW:
 		switch (chan->type) {
@@ -255,13 +260,21 @@ static int gp2ap002_read_raw(struct iio_dev *indio_dev,
 			if (ret < 0)
 				return ret;
 			*val = ret;
-			return IIO_VAL_INT;
+			ret = IIO_VAL_INT;
+			goto out;
 		default:
-			return -EINVAL;
+			ret = -EINVAL;
+			goto out;
 		}
 	default:
-		return -EINVAL;
+		ret = -EINVAL;
 	}
+
+out:
+	pm_runtime_mark_last_busy(gp2ap002->dev);
+	pm_runtime_put_autosuspend(gp2ap002->dev);
+
+	return ret;
 }
 
 static int gp2ap002_init(struct gp2ap002 *gp2ap002)