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Message-ID: <20250412123148.00124102@jic23-huawei>
Date: Sat, 12 Apr 2025 12:31:48 +0100
From: Jonathan Cameron <jic23@...nel.org>
To: Bartosz Golaszewski <brgl@...ev.pl>
Cc: Lars-Peter Clausen <lars@...afoo.de>, Michael Hennerich
<Michael.Hennerich@...log.com>, Linus Walleij <linus.walleij@...aro.org>,
Cosmin Tanislav <cosmin.tanislav@...log.com>, linux-iio@...r.kernel.org,
linux-kernel@...r.kernel.org, linux-gpio@...r.kernel.org, Bartosz
Golaszewski <bartosz.golaszewski@...aro.org>
Subject: Re: [PATCH v2 2/7] iio: dac: ad5592r: use lock guards
On Wed, 09 Apr 2025 10:40:40 +0200
Bartosz Golaszewski <brgl@...ev.pl> wrote:
> From: Bartosz Golaszewski <bartosz.golaszewski@...aro.org>
>
> Use lock guards from linux/cleanup.h to simplify the code and remove
> some labels.
>
> Note that we need to initialize some variables even though it's not
> technically required as scoped_guards() are implemented as for loops.
Needed a tweak for my llvm test build to work.
diff --git a/drivers/iio/dac/ad5592r-base.c b/drivers/iio/dac/ad5592r-base.c
index ada60f5ff1b6..32e63a159d86 100644
--- a/drivers/iio/dac/ad5592r-base.c
+++ b/drivers/iio/dac/ad5592r-base.c
@@ -414,7 +414,7 @@ static int ad5592r_read_raw(struct iio_dev *iio_dev,
*val2 = chan->scan_type.realbits;
return IIO_VAL_FRACTIONAL_LOG2;
- case IIO_CHAN_INFO_OFFSET:
+ case IIO_CHAN_INFO_OFFSET: {
ret = ad5592r_get_vref(st);
guard(mutex)(&st->lock);
@@ -425,6 +425,7 @@ static int ad5592r_read_raw(struct iio_dev *iio_dev,
*val = (-75365 * 25) / ret;
return IIO_VAL_INT;
+ }
default:
return -EINVAL;
}
Scope gets messy in switch statements.
>
> Signed-off-by: Bartosz Golaszewski <bartosz.golaszewski@...aro.org>
> ---
> drivers/iio/dac/ad5592r-base.c | 132 +++++++++++++++++------------------------
> 1 file changed, 54 insertions(+), 78 deletions(-)
>
> diff --git a/drivers/iio/dac/ad5592r-base.c b/drivers/iio/dac/ad5592r-base.c
> index eb85907f61ae..ada60f5ff1b6 100644
> --- a/drivers/iio/dac/ad5592r-base.c
> +++ b/drivers/iio/dac/ad5592r-base.c
> @@ -7,6 +7,7 @@
> */
>
> #include <linux/bitops.h>
> +#include <linux/cleanup.h>
> #include <linux/delay.h>
> #include <linux/iio/iio.h>
> #include <linux/module.h>
> @@ -24,16 +25,14 @@ static int ad5592r_gpio_get(struct gpio_chip *chip, unsigned offset)
> {
> struct ad5592r_state *st = gpiochip_get_data(chip);
> int ret = 0;
> - u8 val;
> + u8 val = 0;
>
> - mutex_lock(&st->gpio_lock);
> -
> - if (st->gpio_out & BIT(offset))
> - val = st->gpio_val;
> - else
> - ret = st->ops->gpio_read(st, &val);
> -
> - mutex_unlock(&st->gpio_lock);
> + scoped_guard(mutex, &st->gpio_lock) {
> + if (st->gpio_out & BIT(offset))
> + val = st->gpio_val;
> + else
> + ret = st->ops->gpio_read(st, &val);
> + }
>
> if (ret < 0)
> return ret;
> @@ -45,7 +44,7 @@ static void ad5592r_gpio_set(struct gpio_chip *chip, unsigned offset, int value)
> {
> struct ad5592r_state *st = gpiochip_get_data(chip);
>
> - mutex_lock(&st->gpio_lock);
> + guard(mutex)(&st->gpio_lock);
>
> if (value)
> st->gpio_val |= BIT(offset);
> @@ -53,8 +52,6 @@ static void ad5592r_gpio_set(struct gpio_chip *chip, unsigned offset, int value)
> st->gpio_val &= ~BIT(offset);
>
> st->ops->reg_write(st, AD5592R_REG_GPIO_SET, st->gpio_val);
> -
> - mutex_unlock(&st->gpio_lock);
> }
>
> static int ad5592r_gpio_direction_input(struct gpio_chip *chip, unsigned offset)
> @@ -62,21 +59,16 @@ static int ad5592r_gpio_direction_input(struct gpio_chip *chip, unsigned offset)
> struct ad5592r_state *st = gpiochip_get_data(chip);
> int ret;
>
> - mutex_lock(&st->gpio_lock);
> + guard(mutex)(&st->gpio_lock);
>
> st->gpio_out &= ~BIT(offset);
> st->gpio_in |= BIT(offset);
>
> ret = st->ops->reg_write(st, AD5592R_REG_GPIO_OUT_EN, st->gpio_out);
> if (ret < 0)
> - goto err_unlock;
> + return ret;
>
> - ret = st->ops->reg_write(st, AD5592R_REG_GPIO_IN_EN, st->gpio_in);
> -
> -err_unlock:
> - mutex_unlock(&st->gpio_lock);
> -
> - return ret;
> + return st->ops->reg_write(st, AD5592R_REG_GPIO_IN_EN, st->gpio_in);
> }
>
> static int ad5592r_gpio_direction_output(struct gpio_chip *chip,
> @@ -85,7 +77,7 @@ static int ad5592r_gpio_direction_output(struct gpio_chip *chip,
> struct ad5592r_state *st = gpiochip_get_data(chip);
> int ret;
>
> - mutex_lock(&st->gpio_lock);
> + guard(mutex)(&st->gpio_lock);
>
> if (value)
> st->gpio_val |= BIT(offset);
> @@ -97,18 +89,13 @@ static int ad5592r_gpio_direction_output(struct gpio_chip *chip,
>
> ret = st->ops->reg_write(st, AD5592R_REG_GPIO_SET, st->gpio_val);
> if (ret < 0)
> - goto err_unlock;
> + return ret;
>
> ret = st->ops->reg_write(st, AD5592R_REG_GPIO_OUT_EN, st->gpio_out);
> if (ret < 0)
> - goto err_unlock;
> + return ret;
>
> - ret = st->ops->reg_write(st, AD5592R_REG_GPIO_IN_EN, st->gpio_in);
> -
> -err_unlock:
> - mutex_unlock(&st->gpio_lock);
> -
> - return ret;
> + return st->ops->reg_write(st, AD5592R_REG_GPIO_IN_EN, st->gpio_in);
> }
>
> static int ad5592r_gpio_request(struct gpio_chip *chip, unsigned offset)
> @@ -171,10 +158,9 @@ static int ad5592r_reset(struct ad5592r_state *st)
> udelay(1);
> gpiod_set_value(gpio, 1);
> } else {
> - mutex_lock(&st->lock);
> - /* Writing this magic value resets the device */
> - st->ops->reg_write(st, AD5592R_REG_RESET, 0xdac);
> - mutex_unlock(&st->lock);
> + scoped_guard(mutex, &st->lock)
> + /* Writing this magic value resets the device */
> + st->ops->reg_write(st, AD5592R_REG_RESET, 0xdac);
> }
>
> udelay(250);
> @@ -249,46 +235,44 @@ static int ad5592r_set_channel_modes(struct ad5592r_state *st)
> }
> }
>
> - mutex_lock(&st->lock);
> + guard(mutex)(&st->lock);
>
> /* Pull down unused pins to GND */
> ret = ops->reg_write(st, AD5592R_REG_PULLDOWN, pulldown);
> if (ret)
> - goto err_unlock;
> + return ret;
>
> ret = ops->reg_write(st, AD5592R_REG_TRISTATE, tristate);
> if (ret)
> - goto err_unlock;
> + return ret;
>
> /* Configure pins that we use */
> ret = ops->reg_write(st, AD5592R_REG_DAC_EN, dac);
> if (ret)
> - goto err_unlock;
> + return ret;
>
> ret = ops->reg_write(st, AD5592R_REG_ADC_EN, adc);
> if (ret)
> - goto err_unlock;
> + return ret;
>
> ret = ops->reg_write(st, AD5592R_REG_GPIO_SET, st->gpio_val);
> if (ret)
> - goto err_unlock;
> + return ret;
>
> ret = ops->reg_write(st, AD5592R_REG_GPIO_OUT_EN, st->gpio_out);
> if (ret)
> - goto err_unlock;
> + return ret;
>
> ret = ops->reg_write(st, AD5592R_REG_GPIO_IN_EN, st->gpio_in);
> if (ret)
> - goto err_unlock;
> + return ret;
>
> /* Verify that we can read back at least one register */
> ret = ops->reg_read(st, AD5592R_REG_ADC_EN, &read_back);
> if (!ret && (read_back & 0xff) != adc)
> - ret = -EIO;
> + return -EIO;
>
> -err_unlock:
> - mutex_unlock(&st->lock);
> - return ret;
> + return 0;
> }
>
> static int ad5592r_reset_channel_modes(struct ad5592r_state *st)
> @@ -305,7 +289,7 @@ static int ad5592r_write_raw(struct iio_dev *iio_dev,
> struct iio_chan_spec const *chan, int val, int val2, long mask)
> {
> struct ad5592r_state *st = iio_priv(iio_dev);
> - int ret;
> + int ret = 0;
>
> switch (mask) {
> case IIO_CHAN_INFO_RAW:
> @@ -316,11 +300,11 @@ static int ad5592r_write_raw(struct iio_dev *iio_dev,
> if (!chan->output)
> return -EINVAL;
>
> - mutex_lock(&st->lock);
> - ret = st->ops->write_dac(st, chan->channel, val);
> - if (!ret)
> - st->cached_dac[chan->channel] = val;
> - mutex_unlock(&st->lock);
> + scoped_guard(mutex, &st->lock) {
> + ret = st->ops->write_dac(st, chan->channel, val);
> + if (!ret)
> + st->cached_dac[chan->channel] = val;
> + }
> return ret;
> case IIO_CHAN_INFO_SCALE:
> if (chan->type == IIO_VOLTAGE) {
> @@ -335,7 +319,7 @@ static int ad5592r_write_raw(struct iio_dev *iio_dev,
> else
> return -EINVAL;
>
> - mutex_lock(&st->lock);
> + guard(mutex)(&st->lock);
>
> ret = st->ops->reg_read(st, AD5592R_REG_CTRL,
> &st->cached_gp_ctrl);
> @@ -360,11 +344,8 @@ static int ad5592r_write_raw(struct iio_dev *iio_dev,
> ~AD5592R_REG_CTRL_ADC_RANGE;
> }
>
> - ret = st->ops->reg_write(st, AD5592R_REG_CTRL,
> - st->cached_gp_ctrl);
> - mutex_unlock(&st->lock);
> -
> - return ret;
> + return st->ops->reg_write(st, AD5592R_REG_CTRL,
> + st->cached_gp_ctrl);
> }
> break;
> default:
> @@ -379,15 +360,15 @@ static int ad5592r_read_raw(struct iio_dev *iio_dev,
> int *val, int *val2, long m)
> {
> struct ad5592r_state *st = iio_priv(iio_dev);
> - u16 read_val;
> - int ret, mult;
> + u16 read_val = 0;
> + int ret = 0, mult = 0;
>
> switch (m) {
> case IIO_CHAN_INFO_RAW:
> if (!chan->output) {
> - mutex_lock(&st->lock);
> - ret = st->ops->read_adc(st, chan->channel, &read_val);
> - mutex_unlock(&st->lock);
> + scoped_guard(mutex, &st->lock)
> + ret = st->ops->read_adc(st, chan->channel,
> + &read_val);
> if (ret)
> return ret;
>
> @@ -400,9 +381,8 @@ static int ad5592r_read_raw(struct iio_dev *iio_dev,
> read_val &= GENMASK(11, 0);
>
> } else {
> - mutex_lock(&st->lock);
> - read_val = st->cached_dac[chan->channel];
> - mutex_unlock(&st->lock);
> + scoped_guard(mutex, &st->lock)
> + read_val = st->cached_dac[chan->channel];
> }
>
> dev_dbg(st->dev, "Channel %u read: 0x%04hX\n",
> @@ -420,16 +400,14 @@ static int ad5592r_read_raw(struct iio_dev *iio_dev,
> return IIO_VAL_INT_PLUS_NANO;
> }
>
> - mutex_lock(&st->lock);
> -
> - if (chan->output)
> - mult = !!(st->cached_gp_ctrl &
> - AD5592R_REG_CTRL_DAC_RANGE);
> - else
> - mult = !!(st->cached_gp_ctrl &
> - AD5592R_REG_CTRL_ADC_RANGE);
> -
> - mutex_unlock(&st->lock);
> + scoped_guard(mutex, &st->lock) {
> + if (chan->output)
> + mult = !!(st->cached_gp_ctrl &
> + AD5592R_REG_CTRL_DAC_RANGE);
> + else
> + mult = !!(st->cached_gp_ctrl &
> + AD5592R_REG_CTRL_ADC_RANGE);
> + }
>
> *val *= ++mult;
>
> @@ -439,15 +417,13 @@ static int ad5592r_read_raw(struct iio_dev *iio_dev,
> case IIO_CHAN_INFO_OFFSET:
> ret = ad5592r_get_vref(st);
>
> - mutex_lock(&st->lock);
> + guard(mutex)(&st->lock);
>
> if (st->cached_gp_ctrl & AD5592R_REG_CTRL_ADC_RANGE)
> *val = (-34365 * 25) / ret;
> else
> *val = (-75365 * 25) / ret;
>
> - mutex_unlock(&st->lock);
> -
> return IIO_VAL_INT;
> default:
> return -EINVAL;
>
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