iio: adc: xilinx-ams: use guard(mutex) for automatic locking

Replace open-coded mutex_lock()/mutex_unlock() pairs with
guard(mutex) to simplify locking and ensure proper unlock on
all control flow paths.

This removes explicit unlock handling, reduces boilerplate,
and avoids potential mistakes in error paths while keeping
the behavior unchanged.

Signed-off-by: Guilherme Ivo Bozi <guilherme.bozi@usp.br>
Reviewed-by: Andy Shevchenko <andriy.shevchenko@intel.com>
Reviewed-by: Salih Erim <salih.erim@amd.com>
Tested-by: Salih Erim <salih.erim@amd.com>
Signed-off-by: Jonathan Cameron <jic23@kernel.org>

Author: guilhermeivo

drivers/iio/adc/xilinx-ams.c

@@ -720,22 +720,20 @@ static int ams_read_raw(struct iio_dev *indio_dev,
 	int ret;
 
 	switch (mask) {
-	case IIO_CHAN_INFO_RAW:
-		mutex_lock(&ams->lock);
+	case IIO_CHAN_INFO_RAW: {
+		guard(mutex)(&ams->lock);
 		if (chan->scan_index >= AMS_CTRL_SEQ_BASE) {
 			ret = ams_read_vcc_reg(ams, chan->address, val);
 			if (ret)
-				goto unlock_mutex;
+				return ret;
 			ams_enable_channel_sequence(indio_dev);
 		} else if (chan->scan_index >= AMS_PS_SEQ_MAX)
 			*val = readl(ams->pl_base + chan->address);
 		else
 			*val = readl(ams->ps_base + chan->address);
 
-		ret = IIO_VAL_INT;
-unlock_mutex:
-		mutex_unlock(&ams->lock);
-		return ret;
+		return IIO_VAL_INT;
+	}
 	case IIO_CHAN_INFO_SCALE:
 		switch (chan->type) {
 		case IIO_VOLTAGE:
@@ -939,7 +937,7 @@ static int ams_write_event_config(struct iio_dev *indio_dev,
 
 	alarm = ams_get_alarm_mask(chan->scan_index);
 
-	mutex_lock(&ams->lock);
+	guard(mutex)(&ams->lock);
 
 	if (state)
 		ams->alarm_mask |= alarm;
@@ -948,8 +946,6 @@ static int ams_write_event_config(struct iio_dev *indio_dev,
 
 	ams_update_alarm(ams, ams->alarm_mask);
 
-	mutex_unlock(&ams->lock);
-
 	return 0;
 }
 
@@ -962,15 +958,13 @@ static int ams_read_event_value(struct iio_dev *indio_dev,
 	struct ams *ams = iio_priv(indio_dev);
 	unsigned int offset = ams_get_alarm_offset(chan->scan_index, dir);
 
-	mutex_lock(&ams->lock);
+	guard(mutex)(&ams->lock);
 
 	if (chan->scan_index >= AMS_PS_SEQ_MAX)
 		*val = readl(ams->pl_base + offset);
 	else
 		*val = readl(ams->ps_base + offset);
 
-	mutex_unlock(&ams->lock);
-
 	return IIO_VAL_INT;
 }
 
@@ -983,7 +977,7 @@ static int ams_write_event_value(struct iio_dev *indio_dev,
 	struct ams *ams = iio_priv(indio_dev);
 	unsigned int offset;
 
-	mutex_lock(&ams->lock);
+	guard(mutex)(&ams->lock);
 
 	/* Set temperature channel threshold to direct threshold */
 	if (chan->type == IIO_TEMP) {
@@ -1005,8 +999,6 @@ static int ams_write_event_value(struct iio_dev *indio_dev,
 	else
 		writel(val, ams->ps_base + offset);
 
-	mutex_unlock(&ams->lock);
-
 	return 0;
 }