[PATCH v8 03/12] iio: ssp_sensors: refactor transfer logic into helper

[Sanjay Chitroda <sanjayembeddedse@gmail.com>]

From: Sanjay Chitroda <sanjayembeddedse@gmail.com>

Extract the core transfer logic under comm_lock into a new
__ssp_do_transfer() helper. The change is preparatory for converting
mutex usage to guard() helpers in subsequent patches.

This restructuring simplifies ssp_do_transfer() and makes the
transfer flow easier to follow.

No functional change intended.

Signed-off-by: Sanjay Chitroda <sanjayembeddedse@gmail.com>
---
 drivers/iio/common/ssp_sensors/ssp_spi.c | 50 +++++++++++++++---------
 1 file changed, 32 insertions(+), 18 deletions(-)

diff --git a/drivers/iio/common/ssp_sensors/ssp_spi.c b/drivers/iio/common/ssp_sensors/ssp_spi.c
index 3d377a482161..ebcda6de56c4 100644
--- a/drivers/iio/common/ssp_sensors/ssp_spi.c
+++ b/drivers/iio/common/ssp_sensors/ssp_spi.c
@@ -196,20 +196,13 @@ static inline void ssp_pending_del(struct ssp_data *data, struct ssp_msg *msg,
 	mutex_unlock(&data->pending_lock);
 }
 
-static int ssp_do_transfer(struct ssp_data *data, struct ssp_msg *msg,
-			   struct completion *done, int timeout)
+static int __ssp_do_transfer(struct ssp_data *data, struct ssp_msg *msg,
+			     bool no_irq)
 {
 	int status;
-	/*
-	 * check if this is a short one way message or the whole transfer has
-	 * second part after an interrupt
-	 */
-	const bool use_no_irq = msg->length == 0;
 
-	if (data->shut_down)
-		return -EPERM;
-
-	msg->done = done;
+	/* msg->done must be initialized by caller */
+	WARN_ON(!msg->done);
 
 	mutex_lock(&data->comm_lock);
 
@@ -224,15 +217,41 @@ static int ssp_do_transfer(struct ssp_data *data, struct ssp_msg *msg,
 		goto _error_locked;
 	}
 
-	ssp_pending_add(data, msg, use_no_irq);
+	ssp_pending_add(data, msg, no_irq);
 
 	status = ssp_check_lines(data, true);
 	if (status < 0) {
-		ssp_pending_del(data, msg, use_no_irq);
+		ssp_pending_del(data, msg, no_irq);
 		goto _error_locked;
 	}
 
 	mutex_unlock(&data->comm_lock);
+	return 0;
+
+_error_locked:
+	mutex_unlock(&data->comm_lock);
+	data->timeout_cnt++;
+	return status;
+}
+
+static int ssp_do_transfer(struct ssp_data *data, struct ssp_msg *msg,
+			   struct completion *done, int timeout)
+{
+	int status;
+	/*
+	 * check if this is a short one way message or the whole transfer has
+	 * second part after an interrupt
+	 */
+	const bool use_no_irq = msg->length == 0;
+
+	if (data->shut_down)
+		return -EPERM;
+
+	msg->done = done;
+
+	status = __ssp_do_transfer(data, msg, use_no_irq);
+	if (status < 0)
+		return status;
 
 	if (!use_no_irq && done &&
 	    !wait_for_completion_timeout(done, msecs_to_jiffies(timeout))) {
@@ -243,11 +262,6 @@ static int ssp_do_transfer(struct ssp_data *data, struct ssp_msg *msg,
 	}
 
 	return 0;
-
-_error_locked:
-	mutex_unlock(&data->comm_lock);
-	data->timeout_cnt++;
-	return status;
 }
 
 static inline int ssp_spi_sync_command(struct ssp_data *data,
-- 
2.34.1