iio: gyro: itg3200_core: do not use internal iio_dev lock

The iio_device lock is only meant for internal use. Hence define a
device local lock to protect against concurrent accesses.

While at it, properly include "mutex.h" for mutex related APIs.
Signed-off-by: Nuno Sá <nuno.sa@analog.com>
Link: https://lore.kernel.org/r/20221004134909.1692021-13-nuno.sa@analog.comSigned-off-by: Jonathan Cameron <Jonathan.Cameron@huawei.com>

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:
@@ -336,6 +338,8 @@ static int itg3200_probe(struct i2c_client *client,
 	if (ret)
 		goto error_remove_trigger;
 
+	mutex_init(&st->lock);
+
 	ret = iio_device_register(indio_dev);
 	if (ret)
 		goto error_remove_trigger;

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 {