[PATCH v3] iio: imu: inv_mpu6050: refactor aux read/write to use shared xfer logic

[Isabella Caselli <bellacaselli20@gmail.com>]

Refactors inv_mpu_aux_read() and inv_mpu_aux_write() to extract the common
I2C transfer sequence into inv_mpu_i2c_master_xfer(), which now handles
starting and stopping the I2C master, waiting for completion, disabling
SLV0, and checking for NACK errors.

This refactoring removes code duplication and improves maintainability.
No functional changes are intended.

Signed-off-by: Isabella Caselli <bellacaselli20@gmail.com>
Co-developed-by: Rodrigo Michelassi <rodrigo.michelassi@usp.br>
Signed-off-by: Rodrigo Michelassi <rodrigo.michelassi@usp.br>
---
Sorry about the diff in v2 capturing the changes proposed in v1.
Just to remember the actual changes made after v1:
As requested after sending v1, we removed the newly created refactoring function — which
would have only been used inside inv_mpu_aux.c — and moved the duplicated code directly
into inv_mpu_i2c_master_xfer(), since the status check was always performed immediately
after its execution in both inv_mpu_aux_read() and inv_mpu_aux_write().
---
 drivers/iio/imu/inv_mpu6050/inv_mpu_aux.c | 56 ++++++++---------------
 1 file changed, 20 insertions(+), 36 deletions(-)

diff --git a/drivers/iio/imu/inv_mpu6050/inv_mpu_aux.c b/drivers/iio/imu/inv_mpu6050/inv_mpu_aux.c
index 8a7f29119..970cf5c47 100644
--- a/drivers/iio/imu/inv_mpu6050/inv_mpu_aux.c
+++ b/drivers/iio/imu/inv_mpu6050/inv_mpu_aux.c
@@ -14,6 +14,8 @@
 /*
  * i2c master auxiliary bus transfer function.
  * Requires the i2c operations to be correctly setup before.
+ * Disables SLV0 and checks for NACK status internally.
+ * Assumes that only SLV0 is used for transfers.
  */
 static int inv_mpu_i2c_master_xfer(const struct inv_mpu6050_state *st)
 {
@@ -23,6 +25,7 @@ static int inv_mpu_i2c_master_xfer(const struct inv_mpu6050_state *st)
 	uint8_t d;
 	unsigned int user_ctrl;
 	int ret;
+	unsigned int status;
 
 	/* set sample rate */
 	d = INV_MPU6050_FIFO_RATE_TO_DIVIDER(freq);
@@ -51,12 +54,27 @@ static int inv_mpu_i2c_master_xfer(const struct inv_mpu6050_state *st)
 	if (ret)
 		goto error_restore_rate;
 
+	/* disable i2c slave */
+	ret = regmap_write(st->map, INV_MPU6050_REG_I2C_SLV_CTRL(0), 0);
+	if (ret)
+		goto error_disable_i2c;
+
+	/* check i2c status */
+	ret = regmap_read(st->map, INV_MPU6050_REG_I2C_MST_STATUS, &status);
+	if (ret)
+		return ret;
+
+	if (status & INV_MPU6050_BIT_I2C_SLV0_NACK)
+		return -EIO;
+
 	return 0;
 
 error_stop_i2c:
 	regmap_write(st->map, st->reg->user_ctrl, st->chip_config.user_ctrl);
 error_restore_rate:
 	regmap_write(st->map, st->reg->sample_rate_div, st->chip_config.divider);
+error_disable_i2c:
+	regmap_write(st->map, INV_MPU6050_REG_I2C_SLV_CTRL(0), 0);
 	return ret;
 }
 
@@ -117,7 +135,6 @@ int inv_mpu_aux_init(const struct inv_mpu6050_state *st)
 int inv_mpu_aux_read(const struct inv_mpu6050_state *st, uint8_t addr,
 		     uint8_t reg, uint8_t *val, size_t size)
 {
-	unsigned int status;
 	int ret;
 
 	if (size > 0x0F)
@@ -136,30 +153,14 @@ int inv_mpu_aux_read(const struct inv_mpu6050_state *st, uint8_t addr,
 	if (ret)
 		return ret;
 
-	/* do i2c xfer */
+	/* do i2c xfer, disable i2c slave and check status*/
 	ret = inv_mpu_i2c_master_xfer(st);
-	if (ret)
-		goto error_disable_i2c;
-
-	/* disable i2c slave */
-	ret = regmap_write(st->map, INV_MPU6050_REG_I2C_SLV_CTRL(0), 0);
-	if (ret)
-		goto error_disable_i2c;
-
-	/* check i2c status */
-	ret = regmap_read(st->map, INV_MPU6050_REG_I2C_MST_STATUS, &status);
 	if (ret)
 		return ret;
-	if (status & INV_MPU6050_BIT_I2C_SLV0_NACK)
-		return -EIO;
 
 	/* read data in registers */
 	return regmap_bulk_read(st->map, INV_MPU6050_REG_EXT_SENS_DATA,
 				val, size);
-
-error_disable_i2c:
-	regmap_write(st->map, INV_MPU6050_REG_I2C_SLV_CTRL(0), 0);
-	return ret;
 }
 
 /**
@@ -174,7 +175,6 @@ int inv_mpu_aux_read(const struct inv_mpu6050_state *st, uint8_t addr,
 int inv_mpu_aux_write(const struct inv_mpu6050_state *st, uint8_t addr,
 		      uint8_t reg, uint8_t val)
 {
-	unsigned int status;
 	int ret;
 
 	/* setup i2c SLV0 control: i2c addr, register, value, enable + size */
@@ -192,26 +192,10 @@ int inv_mpu_aux_write(const struct inv_mpu6050_state *st, uint8_t addr,
 	if (ret)
 		return ret;
 
-	/* do i2c xfer */
+	/* do i2c xfer, disable i2c slave and check status*/
 	ret = inv_mpu_i2c_master_xfer(st);
-	if (ret)
-		goto error_disable_i2c;
-
-	/* disable i2c slave */
-	ret = regmap_write(st->map, INV_MPU6050_REG_I2C_SLV_CTRL(0), 0);
-	if (ret)
-		goto error_disable_i2c;
-
-	/* check i2c status */
-	ret = regmap_read(st->map, INV_MPU6050_REG_I2C_MST_STATUS, &status);
 	if (ret)
 		return ret;
-	if (status & INV_MPU6050_BIT_I2C_SLV0_NACK)
-		return -EIO;
 
 	return 0;
-
-error_disable_i2c:
-	regmap_write(st->map, INV_MPU6050_REG_I2C_SLV_CTRL(0), 0);
-	return ret;
 }
-- 
2.43.0