[PATCH 12/15] iio: fyro: itg3200_core: do not use internal iio_dev lock

[Jonathan Cameron]

On Tue, 20 Sep 2022 13:28:18 +0200
Nuno Sá <nuno.sa at analog.com> wrote:

> The iio_device lock is only meant for internal use. Hence define a
> device local lock to protect against concurrent accesses.
As with earlier, add a note about mutex.h include.

Otherwise, looks fine.  My gut feeling is that we should
have a claim_direct_mode() in that write_raw() as well as
changing frequency whilst doing buffered capture is rarely a good
idea, but meh, we don't need to change the ABI so let us not do so.

Jonathan

> 
> Signed-off-by: Nuno Sá <nuno.sa at analog.com>
> ---
>  drivers/iio/gyro/itg3200_core.c  | 9 ++++++---
>  include/linux/iio/gyro/itg3200.h | 2 ++
>  2 files changed, 8 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/iio/gyro/itg3200_core.c b/drivers/iio/gyro/itg3200_core.c
> index 0491c64e1b32..358aa8ac0c6b 100644
> --- a/drivers/iio/gyro/itg3200_core.c
> +++ b/drivers/iio/gyro/itg3200_core.c
> @@ -18,6 +18,7 @@
>  #include <linux/slab.h>
>  #include <linux/stat.h>
>  #include <linux/module.h>
> +#include <linux/mutex.h>
>  #include <linux/delay.h>
>  
>  #include <linux/iio/iio.h>
> @@ -131,6 +132,7 @@ static int itg3200_write_raw(struct iio_dev *indio_dev,
>  			     int val2,
>  			     long mask)
>  {
> +	struct itg3200 *st = iio_priv(indio_dev);
>  	int ret;
>  	u8 t;
>  
> @@ -139,11 +141,11 @@ static int itg3200_write_raw(struct iio_dev *indio_dev,
>  		if (val == 0 || val2 != 0)
>  			return -EINVAL;
>  
> -		mutex_lock(&indio_dev->mlock);
> +		mutex_lock(&st->lock);
>  
>  		ret = itg3200_read_reg_8(indio_dev, ITG3200_REG_DLPF, &t);
>  		if (ret) {
> -			mutex_unlock(&indio_dev->mlock);
> +			mutex_unlock(&st->lock);
>  			return ret;
>  		}
>  		t = ((t & ITG3200_DLPF_CFG_MASK) ? 1000u : 8000u) / val - 1;
> @@ -152,7 +154,7 @@ static int itg3200_write_raw(struct iio_dev *indio_dev,
>  					  ITG3200_REG_SAMPLE_RATE_DIV,
>  					  t);
>  
> -		mutex_unlock(&indio_dev->mlock);
> +		mutex_unlock(&st->lock);
>  		return ret;
>  
>  	default:
> @@ -307,6 +309,7 @@ static int itg3200_probe(struct i2c_client *client,
>  		return -ENOMEM;
>  
>  	st = iio_priv(indio_dev);
> +	mutex_init(&st->lock);
>  
>  	ret = iio_read_mount_matrix(&client->dev, &st->orientation);
>  	if (ret)
> diff --git a/include/linux/iio/gyro/itg3200.h b/include/linux/iio/gyro/itg3200.h
> index a602fe7b84fa..74b6d1cadc86 100644
> --- a/include/linux/iio/gyro/itg3200.h
> +++ b/include/linux/iio/gyro/itg3200.h
> @@ -102,6 +102,8 @@ struct itg3200 {
>  	struct i2c_client	*i2c;
>  	struct iio_trigger	*trig;
>  	struct iio_mount_matrix orientation;
> +	/* lock to protect against multiple access to the device */
> +	struct mutex		lock;
>  };
>  
>  enum ITG3200_SCAN_INDEX {