[RFC PATCH 12/13] iio: dac: ltc2688: Use __free(fwnode_handle) to replace fwnode_handle_put() calls

[Jonathan Cameron <jic23@xxxxxxxxxx>]

From: Jonathan Cameron <Jonathan.Cameron@xxxxxxxxxx>

This use of the new cleanup.h scope based freeing infrastructure allows
us to exit directly from error conditions within the
device_for_each_child_node(dev, child) loop. On normal exit from that
loop no fwnode_handle reference will be held and the child pointer
will be NULL thus making the automatically run fwnode_handle_put() a
noop.

Signed-off-by: Jonathan Cameron <Jonathan.Cameron@xxxxxxxxxx>
Cc: Nuno Sá <nuno.sa@xxxxxxxxxx>
---
 drivers/iio/dac/ltc2688.c | 23 ++++++-----------------
 1 file changed, 6 insertions(+), 17 deletions(-)

diff --git a/drivers/iio/dac/ltc2688.c b/drivers/iio/dac/ltc2688.c
index fc8eb53c65be..e8add3636af9 100644
--- a/drivers/iio/dac/ltc2688.c
+++ b/drivers/iio/dac/ltc2688.c
@@ -746,7 +746,7 @@ static int ltc2688_span_lookup(const struct ltc2688_state *st, int min, int max)
 static int ltc2688_channel_config(struct ltc2688_state *st)
 {
 	struct device *dev = &st->spi->dev;
-	struct fwnode_handle *child;
+	struct fwnode_handle *child __free(fwnode_handle) = NULL;
 	u32 reg, clk_input, val, tmp[2];
 	int ret, span;
 
@@ -754,18 +754,14 @@ static int ltc2688_channel_config(struct ltc2688_state *st)
 		struct ltc2688_chan *chan;
 
 		ret = fwnode_property_read_u32(child, "reg", &reg);
-		if (ret) {
-			fwnode_handle_put(child);
+		if (ret)
 			return dev_err_probe(dev, ret,
 					     "Failed to get reg property\n");
-		}
 
-		if (reg >= LTC2688_DAC_CHANNELS) {
-			fwnode_handle_put(child);
+		if (reg >= LTC2688_DAC_CHANNELS)
 			return dev_err_probe(dev, -EINVAL,
 					     "reg bigger than: %d\n",
 					     LTC2688_DAC_CHANNELS);
-		}
 
 		val = 0;
 		chan = &st->channels[reg];
@@ -786,12 +782,10 @@ static int ltc2688_channel_config(struct ltc2688_state *st)
 		if (!ret) {
 			span = ltc2688_span_lookup(st, (int)tmp[0] / 1000,
 						   tmp[1] / 1000);
-			if (span < 0) {
-				fwnode_handle_put(child);
+			if (span < 0)
 				return dev_err_probe(dev, -EINVAL,
 						     "output range not valid:[%d %d]\n",
 						     tmp[0], tmp[1]);
-			}
 
 			val |= FIELD_PREP(LTC2688_CH_SPAN_MSK, span);
 		}
@@ -800,17 +794,14 @@ static int ltc2688_channel_config(struct ltc2688_state *st)
 					       &clk_input);
 		if (!ret) {
 			if (clk_input >= LTC2688_CH_TGP_MAX) {
-				fwnode_handle_put(child);
 				return dev_err_probe(dev, -EINVAL,
 						     "toggle-dither-input inv value(%d)\n",
 						     clk_input);
 			}
 
 			ret = ltc2688_tgp_clk_setup(st, chan, child, clk_input);
-			if (ret) {
-				fwnode_handle_put(child);
+			if (ret)
 				return ret;
-			}
 
 			/*
 			 * 0 means software toggle which is the default mode.
@@ -844,11 +835,9 @@ static int ltc2688_channel_config(struct ltc2688_state *st)
 
 		ret = regmap_write(st->regmap, LTC2688_CMD_CH_SETTING(reg),
 				   val);
-		if (ret) {
-			fwnode_handle_put(child);
+		if (ret)
 			return dev_err_probe(dev, -EINVAL,
 					     "failed to set chan settings\n");
-		}
 	}
 
 	return 0;
-- 
2.43.0