iio: adc: at91-sama5d2: Move claim of direct mode up a level and use guard()

Move iio_device_claim_direct_mode() up one layer in the call stack,
and use guard() for scope based unlocking to simplify error handling
by allowing direct returns.

Reviewed-by: Claudiu Beznea <[e-mail]>
Link: https://patch.msgid.link/[e-mail]
Signed-off-by: Jonathan Cameron <[e-mail]>

drivers/iio/adc/at91-sama5d2_adc.c

···
  */
 
 #include <linux/bitops.h>
+#include <linux/cleanup.h>
 #include <linux/clk.h>
 #include <linux/delay.h>
 #include <linux/dma-mapping.h>
···
 				     struct iio_chan_spec const *chan, int *val)
 {
 	struct at91_adc_state *st = iio_priv(indio_dev);
-	int ret;
 
-	ret = iio_device_claim_direct_mode(indio_dev);
-	if (ret)
-		return ret;
+	guard(mutex)(&st->lock);
 
-	mutex_lock(&st->lock);
-	ret = at91_adc_read_info_raw(indio_dev, chan, val);
-	mutex_unlock(&st->lock);
-
-	iio_device_release_direct_mode(indio_dev);
-
-	return ret;
+	return at91_adc_read_info_raw(indio_dev, chan, val);
 }
 
 static void at91_adc_temp_sensor_configure(struct at91_adc_state *st,
···
 	u32 tmp;
 	int ret, vbg, vtemp;
 
-	ret = iio_device_claim_direct_mode(indio_dev);
-	if (ret)
-		return ret;
-	mutex_lock(&st->lock);
+	guard(mutex)(&st->lock);
 
 	ret = pm_runtime_resume_and_get(st->dev);
 	if (ret < 0)
-		goto unlock;
+		return ret;
 
 	at91_adc_temp_sensor_configure(st, true);
 
···
 	at91_adc_temp_sensor_configure(st, false);
 	pm_runtime_mark_last_busy(st->dev);
 	pm_runtime_put_autosuspend(st->dev);
-unlock:
-	mutex_unlock(&st->lock);
-	iio_device_release_direct_mode(indio_dev);
 	if (ret < 0)
 		return ret;
 
···
 			     int *val, int *val2, long mask)
 {
 	struct at91_adc_state *st = iio_priv(indio_dev);
+	int ret;
 
 	switch (mask) {
 	case IIO_CHAN_INFO_RAW:
-		return at91_adc_read_info_locked(indio_dev, chan, val);
+		ret = iio_device_claim_direct_mode(indio_dev);
+		if (ret)
+			return ret;
+
+		ret = at91_adc_read_info_locked(indio_dev, chan, val);
+		iio_device_release_direct_mode(indio_dev);
+		return ret;
 
 	case IIO_CHAN_INFO_SCALE:
 		*val = st->vref_uv / 1000;
···
 	case IIO_CHAN_INFO_PROCESSED:
 		if (chan->type != IIO_TEMP)
 			return -EINVAL;
-		return at91_adc_read_temp(indio_dev, chan, val);
+		ret = iio_device_claim_direct_mode(indio_dev);
+		if (ret)
+			return ret;
+
+		ret = at91_adc_read_temp(indio_dev, chan, val);
+		iio_device_release_direct_mode(indio_dev);
+
+		return ret;
 
 	case IIO_CHAN_INFO_SAMP_FREQ:
 		*val = at91_adc_get_sample_freq(st);