diff mbox series

[v4,17/17] staging: iio: resolver: ad2s1210: simplify code with guard(mutex)

Message ID 20231005-ad2s1210-mainline-v4-17-ec00746840fc@baylibre.com
State New
Headers
Series iio: resolver: move ad2s1210 out of staging |

Commit Message

David Lechner Oct. 6, 2023, 12:50 a.m. UTC 
  We can simplify the code and get rid of most of the gotos by using
guard(mutex) from cleanup.h.

Signed-off-by: David Lechner <dlechner@baylibre.com>
---

v4 changes: New patch in v4.

 drivers/staging/iio/resolver/ad2s1210.c | 157 ++++++++++----------------------
 1 file changed, 50 insertions(+), 107 deletions(-)

Comments

Jonathan Cameron Oct. 10, 2023, 4:17 p.m. UTC | #1 
On Thu,  5 Oct 2023 19:50:34 -0500
David Lechner <dlechner@baylibre.com> wrote:

> We can simplify the code and get rid of most of the gotos by using
> guard(mutex) from cleanup.h.
You could consider scoped_guard() for a few cases in here, but perhaps
it's better to be consistent and always use the guard() version.

There is a small timing question wrt to the gpio manipulation inline.

> 
> Signed-off-by: David Lechner <dlechner@baylibre.com>
> ---
> 
> v4 changes: New patch in v4.
> 
>  drivers/staging/iio/resolver/ad2s1210.c | 157 ++++++++++----------------------
>  1 file changed, 50 insertions(+), 107 deletions(-)
> 
> diff --git a/drivers/staging/iio/resolver/ad2s1210.c b/drivers/staging/iio/resolver/ad2s1210.c
> index c4e1bc22e8b0..c4e0ffa92dc2 100644
> --- a/drivers/staging/iio/resolver/ad2s1210.c
> +++ b/drivers/staging/iio/resolver/ad2s1210.c
> @@ -47,6 +47,7 @@
>  
>  #include <linux/bitfield.h>
>  #include <linux/bits.h>
> +#include <linux/cleanup.h>
>  #include <linux/clk.h>
>  #include <linux/delay.h>
>  #include <linux/device.h>
> @@ -404,11 +405,13 @@ static int ad2s1210_single_conversion(struct iio_dev *indio_dev,
>  	s64 timestamp;
>  	int ret;
>  
> -	mutex_lock(&st->lock);
> +	guard(mutex)(&st->lock);
> +
>  	gpiod_set_value(st->sample_gpio, 1);
>  	timestamp = iio_get_time_ns(indio_dev);
>  	/* delay (6 * tck + 20) nano seconds */
>  	udelay(1);
> +	gpiod_set_value(st->sample_gpio, 0);
>  
>  	switch (chan->type) {
>  	case IIO_ANGL:
> @@ -418,14 +421,13 @@ static int ad2s1210_single_conversion(struct iio_dev *indio_dev,
>  		ret = ad2s1210_set_mode(st, MOD_VEL);
>  		break;
>  	default:
> -		ret = -EINVAL;
> -		break;
> +		return -EINVAL;
>  	}
>  	if (ret < 0)
> -		goto error_ret;
> +		return ret;
>  	ret = spi_read(st->sdev, &st->sample, 3);
>  	if (ret < 0)
> -		goto error_ret;
> +		return ret;
>  
>  	switch (chan->type) {
>  	case IIO_ANGL:
> @@ -437,17 +439,11 @@ static int ad2s1210_single_conversion(struct iio_dev *indio_dev,
>  		ret = IIO_VAL_INT;
>  		break;
>  	default:
> -		ret = -EINVAL;
> -		break;
> +		return -EINVAL;
>  	}
>  
>  	ad2s1210_push_events(indio_dev, st->sample.fault, timestamp);
>  
> -error_ret:
> -	gpiod_set_value(st->sample_gpio, 0);
> -	/* delay (2 * tck + 20) nano seconds */
> -	udelay(1);

Dropping this delay isn't obviously safe (though it probably is given stuff done before we exit).
I assume there are no rules on holding the gpio down for the register read.
 
If nothing else I think the patch description needs to made an argument for why it is fine.

> -	mutex_unlock(&st->lock);
>  	return ret;
>  }
>
David Lechner Oct. 10, 2023, 5:40 p.m. UTC | #2 
On Tue, Oct 10, 2023 at 11:17 AM Jonathan Cameron <jic23@kernel.org> wrote:
>
> On Thu,  5 Oct 2023 19:50:34 -0500
> David Lechner <dlechner@baylibre.com> wrote:
>
> > We can simplify the code and get rid of most of the gotos by using
> > guard(mutex) from cleanup.h.
> You could consider scoped_guard() for a few cases in here, but perhaps
> it's better to be consistent and always use the guard() version.

Yes, there it doesn't look like there are any cases where there is any
long-running operation that could be done after unlocking the mutex,
so I went with the simpler approach everywhere.

>
> There is a small timing question wrt to the gpio manipulation inline.
>
> >
> > Signed-off-by: David Lechner <dlechner@baylibre.com>
> > ---
> >
> > v4 changes: New patch in v4.
> >
> >  drivers/staging/iio/resolver/ad2s1210.c | 157 ++++++++++----------------------
> >  1 file changed, 50 insertions(+), 107 deletions(-)
> >
> > diff --git a/drivers/staging/iio/resolver/ad2s1210.c b/drivers/staging/iio/resolver/ad2s1210.c
> > index c4e1bc22e8b0..c4e0ffa92dc2 100644
> > --- a/drivers/staging/iio/resolver/ad2s1210.c
> > +++ b/drivers/staging/iio/resolver/ad2s1210.c
> > @@ -47,6 +47,7 @@
> >
> >  #include <linux/bitfield.h>
> >  #include <linux/bits.h>
> > +#include <linux/cleanup.h>
> >  #include <linux/clk.h>
> >  #include <linux/delay.h>
> >  #include <linux/device.h>
> > @@ -404,11 +405,13 @@ static int ad2s1210_single_conversion(struct iio_dev *indio_dev,
> >       s64 timestamp;
> >       int ret;
> >
> > -     mutex_lock(&st->lock);
> > +     guard(mutex)(&st->lock);
> > +
> >       gpiod_set_value(st->sample_gpio, 1);
> >       timestamp = iio_get_time_ns(indio_dev);
> >       /* delay (6 * tck + 20) nano seconds */
> >       udelay(1);
> > +     gpiod_set_value(st->sample_gpio, 0);
> >
> >       switch (chan->type) {
> >       case IIO_ANGL:
> > @@ -418,14 +421,13 @@ static int ad2s1210_single_conversion(struct iio_dev *indio_dev,
> >               ret = ad2s1210_set_mode(st, MOD_VEL);
> >               break;
> >       default:
> > -             ret = -EINVAL;
> > -             break;
> > +             return -EINVAL;
> >       }
> >       if (ret < 0)
> > -             goto error_ret;
> > +             return ret;
> >       ret = spi_read(st->sdev, &st->sample, 3);
> >       if (ret < 0)
> > -             goto error_ret;
> > +             return ret;
> >
> >       switch (chan->type) {
> >       case IIO_ANGL:
> > @@ -437,17 +439,11 @@ static int ad2s1210_single_conversion(struct iio_dev *indio_dev,
> >               ret = IIO_VAL_INT;
> >               break;
> >       default:
> > -             ret = -EINVAL;
> > -             break;
> > +             return -EINVAL;
> >       }
> >
> >       ad2s1210_push_events(indio_dev, st->sample.fault, timestamp);
> >
> > -error_ret:
> > -     gpiod_set_value(st->sample_gpio, 0);
> > -     /* delay (2 * tck + 20) nano seconds */
> > -     udelay(1);
>
> Dropping this delay isn't obviously safe (though it probably is given stuff done before we exit).
> I assume there are no rules on holding the gpio down for the register read.

Correct. The SAMPLE gpio only needs to be held for a short time (~350
nanoseconds) to latch in the current values, then it doesn't matter
when it is released. (Figure 35 in datasheet)

>
> If nothing else I think the patch description needs to made an argument for why it is fine.

The longest possible delay needed after releasing the SAMPLE line
before reasserting is ~350 nanoseconds. Is there a rule of thumb for
deciding when there are enough instructions that no processor could
execute them faster than this vs. when we should add an explicit
delay?

I think I will consider adding a patch in the next round to refactor
the SAMPLE toggle to a separate function so we can be sure it is
handled the same in all cases.

>
> > -     mutex_unlock(&st->lock);
> >       return ret;
> >  }
> >
Jonathan Cameron Oct. 10, 2023, 5:46 p.m. UTC | #3 
On Tue, 10 Oct 2023 12:40:03 -0500
David Lechner <dlechner@baylibre.com> wrote:

> On Tue, Oct 10, 2023 at 11:17 AM Jonathan Cameron <jic23@kernel.org> wrote:
> >
> > On Thu,  5 Oct 2023 19:50:34 -0500
> > David Lechner <dlechner@baylibre.com> wrote:
> >  
> > > We can simplify the code and get rid of most of the gotos by using
> > > guard(mutex) from cleanup.h.  
> > You could consider scoped_guard() for a few cases in here, but perhaps
> > it's better to be consistent and always use the guard() version.  
> 
> Yes, there it doesn't look like there are any cases where there is any
> long-running operation that could be done after unlocking the mutex,
> so I went with the simpler approach everywhere.
> 
> >
> > There is a small timing question wrt to the gpio manipulation inline.
> >  
> > >
> > > Signed-off-by: David Lechner <dlechner@baylibre.com>
> > > ---
> > >
> > > v4 changes: New patch in v4.
> > >
> > >  drivers/staging/iio/resolver/ad2s1210.c | 157 ++++++++++----------------------
> > >  1 file changed, 50 insertions(+), 107 deletions(-)
> > >
> > > diff --git a/drivers/staging/iio/resolver/ad2s1210.c b/drivers/staging/iio/resolver/ad2s1210.c
> > > index c4e1bc22e8b0..c4e0ffa92dc2 100644
> > > --- a/drivers/staging/iio/resolver/ad2s1210.c
> > > +++ b/drivers/staging/iio/resolver/ad2s1210.c
> > > @@ -47,6 +47,7 @@
> > >
> > >  #include <linux/bitfield.h>
> > >  #include <linux/bits.h>
> > > +#include <linux/cleanup.h>
> > >  #include <linux/clk.h>
> > >  #include <linux/delay.h>
> > >  #include <linux/device.h>
> > > @@ -404,11 +405,13 @@ static int ad2s1210_single_conversion(struct iio_dev *indio_dev,
> > >       s64 timestamp;
> > >       int ret;
> > >
> > > -     mutex_lock(&st->lock);
> > > +     guard(mutex)(&st->lock);
> > > +
> > >       gpiod_set_value(st->sample_gpio, 1);
> > >       timestamp = iio_get_time_ns(indio_dev);
> > >       /* delay (6 * tck + 20) nano seconds */
> > >       udelay(1);
> > > +     gpiod_set_value(st->sample_gpio, 0);
> > >
> > >       switch (chan->type) {
> > >       case IIO_ANGL:
> > > @@ -418,14 +421,13 @@ static int ad2s1210_single_conversion(struct iio_dev *indio_dev,
> > >               ret = ad2s1210_set_mode(st, MOD_VEL);
> > >               break;
> > >       default:
> > > -             ret = -EINVAL;
> > > -             break;
> > > +             return -EINVAL;
> > >       }
> > >       if (ret < 0)
> > > -             goto error_ret;
> > > +             return ret;
> > >       ret = spi_read(st->sdev, &st->sample, 3);
> > >       if (ret < 0)
> > > -             goto error_ret;
> > > +             return ret;
> > >
> > >       switch (chan->type) {
> > >       case IIO_ANGL:
> > > @@ -437,17 +439,11 @@ static int ad2s1210_single_conversion(struct iio_dev *indio_dev,
> > >               ret = IIO_VAL_INT;
> > >               break;
> > >       default:
> > > -             ret = -EINVAL;
> > > -             break;
> > > +             return -EINVAL;
> > >       }
> > >
> > >       ad2s1210_push_events(indio_dev, st->sample.fault, timestamp);
> > >
> > > -error_ret:
> > > -     gpiod_set_value(st->sample_gpio, 0);
> > > -     /* delay (2 * tck + 20) nano seconds */
> > > -     udelay(1);  
> >
> > Dropping this delay isn't obviously safe (though it probably is given stuff done before we exit).
> > I assume there are no rules on holding the gpio down for the register read.  
> 
> Correct. The SAMPLE gpio only needs to be held for a short time (~350
> nanoseconds) to latch in the current values, then it doesn't matter
> when it is released. (Figure 35 in datasheet)
> 
> >
> > If nothing else I think the patch description needs to made an argument for why it is fine.  
> 
> The longest possible delay needed after releasing the SAMPLE line
> before reasserting is ~350 nanoseconds. Is there a rule of thumb for
> deciding when there are enough instructions that no processor could
> execute them faster than this vs. when we should add an explicit
> delay?
Almost always use an explicit delay as then we don't have to think about it.

> 
> I think I will consider adding a patch in the next round to refactor
> the SAMPLE toggle to a separate function so we can be sure it is
> handled the same in all cases.
Sounds good.

Jonathan

> 
> >  
> > > -     mutex_unlock(&st->lock);
> > >       return ret;
> > >  }
> > >
diff mbox series

Patch

diff --git a/drivers/staging/iio/resolver/ad2s1210.c b/drivers/staging/iio/resolver/ad2s1210.c
index c4e1bc22e8b0..c4e0ffa92dc2 100644
--- a/drivers/staging/iio/resolver/ad2s1210.c
+++ b/drivers/staging/iio/resolver/ad2s1210.c
@@ -47,6 +47,7 @@ 
 
 #include <linux/bitfield.h>
 #include <linux/bits.h>
+#include <linux/cleanup.h>
 #include <linux/clk.h>
 #include <linux/delay.h>
 #include <linux/device.h>
@@ -404,11 +405,13 @@  static int ad2s1210_single_conversion(struct iio_dev *indio_dev,
 	s64 timestamp;
 	int ret;
 
-	mutex_lock(&st->lock);
+	guard(mutex)(&st->lock);
+
 	gpiod_set_value(st->sample_gpio, 1);
 	timestamp = iio_get_time_ns(indio_dev);
 	/* delay (6 * tck + 20) nano seconds */
 	udelay(1);
+	gpiod_set_value(st->sample_gpio, 0);
 
 	switch (chan->type) {
 	case IIO_ANGL:
@@ -418,14 +421,13 @@  static int ad2s1210_single_conversion(struct iio_dev *indio_dev,
 		ret = ad2s1210_set_mode(st, MOD_VEL);
 		break;
 	default:
-		ret = -EINVAL;
-		break;
+		return -EINVAL;
 	}
 	if (ret < 0)
-		goto error_ret;
+		return ret;
 	ret = spi_read(st->sdev, &st->sample, 3);
 	if (ret < 0)
-		goto error_ret;
+		return ret;
 
 	switch (chan->type) {
 	case IIO_ANGL:
@@ -437,17 +439,11 @@  static int ad2s1210_single_conversion(struct iio_dev *indio_dev,
 		ret = IIO_VAL_INT;
 		break;
 	default:
-		ret = -EINVAL;
-		break;
+		return -EINVAL;
 	}
 
 	ad2s1210_push_events(indio_dev, st->sample.fault, timestamp);
 
-error_ret:
-	gpiod_set_value(st->sample_gpio, 0);
-	/* delay (2 * tck + 20) nano seconds */
-	udelay(1);
-	mutex_unlock(&st->lock);
 	return ret;
 }
 
@@ -455,11 +451,9 @@  static int ad2s1210_get_hysteresis(struct ad2s1210_state *st, int *val)
 {
 	int ret;
 
-	mutex_lock(&st->lock);
+	guard(mutex)(&st->lock);
 	ret = regmap_test_bits(st->regmap, AD2S1210_REG_CONTROL,
 			       AD2S1210_ENABLE_HYSTERESIS);
-	mutex_unlock(&st->lock);
-
 	if (ret < 0)
 		return ret;
 
@@ -469,15 +463,10 @@  static int ad2s1210_get_hysteresis(struct ad2s1210_state *st, int *val)
 
 static int ad2s1210_set_hysteresis(struct ad2s1210_state *st, int val)
 {
-	int ret;
-
-	mutex_lock(&st->lock);
-	ret = regmap_update_bits(st->regmap, AD2S1210_REG_CONTROL,
-				 AD2S1210_ENABLE_HYSTERESIS,
-				 val ? AD2S1210_ENABLE_HYSTERESIS : 0);
-	mutex_unlock(&st->lock);
-
-	return ret;
+	guard(mutex)(&st->lock);
+	return regmap_update_bits(st->regmap, AD2S1210_REG_CONTROL,
+				  AD2S1210_ENABLE_HYSTERESIS,
+				  val ? AD2S1210_ENABLE_HYSTERESIS : 0);
 }
 
 static int ad2s1210_get_phase_lock_range(struct ad2s1210_state *st,
@@ -485,11 +474,9 @@  static int ad2s1210_get_phase_lock_range(struct ad2s1210_state *st,
 {
 	int ret;
 
-	mutex_lock(&st->lock);
+	guard(mutex)(&st->lock);
 	ret = regmap_test_bits(st->regmap, AD2S1210_REG_CONTROL,
 			       AD2S1210_PHASE_LOCK_RANGE_44);
-	mutex_unlock(&st->lock);
-
 	if (ret < 0)
 		return ret;
 
@@ -509,7 +496,7 @@  static int ad2s1210_get_phase_lock_range(struct ad2s1210_state *st,
 static int ad2s1210_set_phase_lock_range(struct ad2s1210_state *st,
 					 int val, int val2)
 {
-	int deg, ret;
+	int deg;
 
 	/* convert radians to degrees - only two allowable values */
 	if (val == PHASE_44_DEG_TO_RAD_INT && val2 == PHASE_44_DEG_TO_RAD_MICRO)
@@ -520,12 +507,10 @@  static int ad2s1210_set_phase_lock_range(struct ad2s1210_state *st,
 	else
 		return -EINVAL;
 
-	mutex_lock(&st->lock);
-	ret = regmap_update_bits(st->regmap, AD2S1210_REG_CONTROL,
-				 AD2S1210_PHASE_LOCK_RANGE_44,
-				 deg == 44 ? AD2S1210_PHASE_LOCK_RANGE_44 : 0);
-	mutex_unlock(&st->lock);
-	return ret;
+	guard(mutex)(&st->lock);
+	return regmap_update_bits(st->regmap, AD2S1210_REG_CONTROL,
+				  AD2S1210_PHASE_LOCK_RANGE_44,
+				  deg == 44 ? AD2S1210_PHASE_LOCK_RANGE_44 : 0);
 }
 
 /* map resolution to microradians/LSB for LOT registers */
@@ -542,10 +527,8 @@  static int ad2s1210_get_voltage_threshold(struct ad2s1210_state *st,
 	unsigned int reg_val;
 	int ret;
 
-	mutex_lock(&st->lock);
+	guard(mutex)(&st->lock);
 	ret = regmap_read(st->regmap, reg, &reg_val);
-	mutex_unlock(&st->lock);
-
 	if (ret < 0)
 		return ret;
 
@@ -557,15 +540,11 @@  static int ad2s1210_set_voltage_threshold(struct ad2s1210_state *st,
 					  unsigned int reg, int val)
 {
 	unsigned int reg_val;
-	int ret;
 
 	reg_val = val / THRESHOLD_MILLIVOLT_PER_LSB;
 
-	mutex_lock(&st->lock);
-	ret = regmap_write(st->regmap, reg, reg_val);
-	mutex_unlock(&st->lock);
-
-	return ret;
+	guard(mutex)(&st->lock);
+	return regmap_write(st->regmap, reg, reg_val);
 }
 
 static int ad2s1210_get_lot_high_threshold(struct ad2s1210_state *st,
@@ -574,10 +553,8 @@  static int ad2s1210_get_lot_high_threshold(struct ad2s1210_state *st,
 	unsigned int reg_val;
 	int ret;
 
-	mutex_lock(&st->lock);
+	guard(mutex)(&st->lock);
 	ret = regmap_read(st->regmap, AD2S1210_REG_LOT_HIGH_THRD, &reg_val);
-	mutex_unlock(&st->lock);
-
 	if (ret < 0)
 		return ret;
 
@@ -596,18 +573,18 @@  static int ad2s1210_set_lot_high_threshold(struct ad2s1210_state *st,
 	if (val != 0)
 		return -EINVAL;
 
-	mutex_lock(&st->lock);
+	guard(mutex)(&st->lock);
 	/*
 	 * We need to read both high and low registers first so we can preserve
 	 * the hysteresis.
 	 */
 	ret = regmap_read(st->regmap, AD2S1210_REG_LOT_HIGH_THRD, &high_reg_val);
 	if (ret < 0)
-		goto error_ret;
+		return ret;
 
 	ret = regmap_read(st->regmap, AD2S1210_REG_LOT_LOW_THRD, &low_reg_val);
 	if (ret < 0)
-		goto error_ret;
+		return ret;
 
 	hysteresis = high_reg_val - low_reg_val;
 	high_reg_val = val2 / ad2s1210_lot_threshold_urad_per_lsb[st->resolution];
@@ -615,14 +592,9 @@  static int ad2s1210_set_lot_high_threshold(struct ad2s1210_state *st,
 
 	ret = regmap_write(st->regmap, AD2S1210_REG_LOT_HIGH_THRD, high_reg_val);
 	if (ret < 0)
-		goto error_ret;
-
-	ret = regmap_write(st->regmap, AD2S1210_REG_LOT_LOW_THRD, low_reg_val);
-
-error_ret:
-	mutex_unlock(&st->lock);
+		return ret;
 
-	return ret;
+	return regmap_write(st->regmap, AD2S1210_REG_LOT_LOW_THRD, low_reg_val);
 }
 
 static int ad2s1210_get_lot_low_threshold(struct ad2s1210_state *st,
@@ -631,16 +603,13 @@  static int ad2s1210_get_lot_low_threshold(struct ad2s1210_state *st,
 	unsigned int high_reg_val, low_reg_val;
 	int ret;
 
-	mutex_lock(&st->lock);
+	guard(mutex)(&st->lock);
+
 	ret = regmap_read(st->regmap, AD2S1210_REG_LOT_HIGH_THRD, &high_reg_val);
 	if (ret < 0)
-		goto error_ret;
+		return ret;
 
 	ret = regmap_read(st->regmap, AD2S1210_REG_LOT_LOW_THRD, &low_reg_val);
-
-error_ret:
-	mutex_unlock(&st->lock);
-
 	if (ret < 0)
 		return ret;
 
@@ -663,18 +632,14 @@  static int ad2s1210_set_lot_low_threshold(struct ad2s1210_state *st,
 
 	hysteresis = val2 / ad2s1210_lot_threshold_urad_per_lsb[st->resolution];
 
-	mutex_lock(&st->lock);
+	guard(mutex)(&st->lock);
+
 	ret = regmap_read(st->regmap, AD2S1210_REG_LOT_HIGH_THRD, &reg_val);
 	if (ret < 0)
-		goto error_ret;
+		return ret;
 
-	ret = regmap_write(st->regmap, AD2S1210_REG_LOT_LOW_THRD,
+	return regmap_write(st->regmap, AD2S1210_REG_LOT_LOW_THRD,
 			   reg_val - hysteresis);
-
-error_ret:
-	mutex_unlock(&st->lock);
-
-	return ret;
 }
 
 static int ad2s1210_get_excitation_frequency(struct ad2s1210_state *st, int *val)
@@ -682,31 +647,23 @@  static int ad2s1210_get_excitation_frequency(struct ad2s1210_state *st, int *val
 	unsigned int reg_val;
 	int ret;
 
-	mutex_lock(&st->lock);
+	guard(mutex)(&st->lock);
+
 	ret = regmap_read(st->regmap, AD2S1210_REG_EXCIT_FREQ, &reg_val);
 	if (ret < 0)
-		goto error_ret;
+		return ret;
 
 	*val = reg_val * st->clkin_hz / (1 << 15);
-	ret = IIO_VAL_INT;
-
-error_ret:
-	mutex_unlock(&st->lock);
-	return ret;
+	return IIO_VAL_INT;
 }
 
 static int ad2s1210_set_excitation_frequency(struct ad2s1210_state *st, int val)
 {
-	int ret;
-
 	if (val < AD2S1210_MIN_EXCIT || val > AD2S1210_MAX_EXCIT)
 		return -EINVAL;
 
-	mutex_lock(&st->lock);
-	ret = ad2s1210_reinit_excitation_frequency(st, val);
-	mutex_unlock(&st->lock);
-
-	return ret;
+	guard(mutex)(&st->lock);
+	return ad2s1210_reinit_excitation_frequency(st, val);
 }
 
 static const int ad2s1210_velocity_scale[] = {
@@ -982,10 +939,8 @@  static ssize_t event_attr_voltage_reg_show(struct device *dev,
 	unsigned int value;
 	int ret;
 
-	mutex_lock(&st->lock);
+	guard(mutex)(&st->lock);
 	ret = regmap_read(st->regmap, iattr->address, &value);
-	mutex_unlock(&st->lock);
-
 	if (ret < 0)
 		return ret;
 
@@ -1005,11 +960,9 @@  static ssize_t event_attr_voltage_reg_store(struct device *dev,
 	if (ret)
 		return -EINVAL;
 
-	mutex_lock(&st->lock);
+	guard(mutex)(&st->lock);
 	ret = regmap_write(st->regmap, iattr->address,
 			   data / THRESHOLD_MILLIVOLT_PER_LSB);
-	mutex_unlock(&st->lock);
-
 	if (ret < 0)
 		return ret;
 
@@ -1083,7 +1036,7 @@  static int ad2s1210_initial(struct ad2s1210_state *st)
 	unsigned int data;
 	int ret;
 
-	mutex_lock(&st->lock);
+	guard(mutex)(&st->lock);
 
 	/* Use default config register value plus resolution from devicetree. */
 	data = FIELD_PREP(AD2S1210_PHASE_LOCK_RANGE_44, 1);
@@ -1093,13 +1046,9 @@  static int ad2s1210_initial(struct ad2s1210_state *st)
 
 	ret = regmap_write(st->regmap, AD2S1210_REG_CONTROL, data);
 	if (ret < 0)
-		goto error_ret;
-
-	ret = ad2s1210_reinit_excitation_frequency(st, AD2S1210_DEF_EXCIT);
+		return ret;
 
-error_ret:
-	mutex_unlock(&st->lock);
-	return ret;
+	return ad2s1210_reinit_excitation_frequency(st, AD2S1210_DEF_EXCIT);
 }
 
 static int ad2s1210_read_label(struct iio_dev *indio_dev,
@@ -1243,18 +1192,13 @@  static int ad2s1210_debugfs_reg_access(struct iio_dev *indio_dev,
 				       unsigned int *readval)
 {
 	struct ad2s1210_state *st = iio_priv(indio_dev);
-	int ret;
 
-	mutex_lock(&st->lock);
+	guard(mutex)(&st->lock);
 
 	if (readval)
-		ret = regmap_read(st->regmap, reg, readval);
-	else
-		ret = regmap_write(st->regmap, reg, writeval);
-
-	mutex_unlock(&st->lock);
+		return regmap_read(st->regmap, reg, readval);
 
-	return ret;
+	return regmap_write(st->regmap, reg, writeval);
 }
 
 static irqreturn_t ad2s1210_trigger_handler(int irq, void *p)
@@ -1265,7 +1209,7 @@  static irqreturn_t ad2s1210_trigger_handler(int irq, void *p)
 	size_t chan = 0;
 	int ret;
 
-	mutex_lock(&st->lock);
+	guard(mutex)(&st->lock);
 
 	memset(&st->scan, 0, sizeof(st->scan));
 	gpiod_set_value(st->sample_gpio, 1);
@@ -1299,7 +1243,6 @@  static irqreturn_t ad2s1210_trigger_handler(int irq, void *p)
 
 error_ret:
 	gpiod_set_value(st->sample_gpio, 0);
-	mutex_unlock(&st->lock);
 	iio_trigger_notify_done(indio_dev->trig);
 
 	return IRQ_HANDLED;