usb: typec: ucsi: rework command execution functions

Rework command execution code to remove recursive calls of
ucsi_exec_command. This also streamlines the sync_control / read(CCI)
read (MESSAGE_IN) sequence, allowing further rework of the command code.

Tested-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Reviewed-by: Heikki Krogerus <heikki.krogerus@linux.intel.com>
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Link: https://lore.kernel.org/r/20240627-ucsi-rework-interface-v4-4-289ddc6874c7@linaro.org
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/usb/typec/ucsi/ucsi.c

@@ -63,27 +63,76 @@ static int ucsi_acknowledge(struct ucsi *ucsi, bool conn_ack)
 	return ucsi->ops->sync_control(ucsi, ctrl);
 }
 
-static int ucsi_exec_command(struct ucsi *ucsi, u64 command);
+static int ucsi_run_command(struct ucsi *ucsi, u64 command, u32 *cci,
+			    void *data, size_t size, bool conn_ack)
+{
+	int ret;
+
+	*cci = 0;
+
+	ret = ucsi->ops->sync_control(ucsi, command);
+	if (ret)
+		return ret;
+
+	ret = ucsi->ops->read_cci(ucsi, cci);
+	if (ret)
+		return ret;
+
+	if (*cci & UCSI_CCI_BUSY)
+		return -EBUSY;
+
+	if (!(*cci & UCSI_CCI_COMMAND_COMPLETE))
+		return -EIO;
+
+	if (*cci & UCSI_CCI_NOT_SUPPORTED) {
+		if (ucsi_acknowledge(ucsi, false) < 0)
+			dev_err(ucsi->dev,
+				"ACK of unsupported command failed\n");
+		return -EOPNOTSUPP;
+	}
+
+	if (*cci & UCSI_CCI_ERROR) {
+		/* Acknowledge the command that failed */
+		ret = ucsi_acknowledge(ucsi, false);
+		return ret ? ret : -EIO;
+	}
+
+	if (data) {
+		ret = ucsi_read_message_in(ucsi, data, size);
+		if (ret)
+			return ret;
+	}
+
+	ret = ucsi_acknowledge(ucsi, conn_ack);
+	if (ret)
+		return ret;
+
+	return 0;
+}
 
 static int ucsi_read_error(struct ucsi *ucsi, u8 connector_num)
 {
 	u64 command;
 	u16 error;
+	u32 cci;
 	int ret;
 
 	command = UCSI_GET_ERROR_STATUS | UCSI_CONNECTOR_NUMBER(connector_num);
-	ret = ucsi_exec_command(ucsi, command);
-	if (ret < 0)
-		return ret;
+	ret = ucsi_run_command(ucsi, command, &cci,
+			       &error, sizeof(error), false);
 
-	ret = ucsi_read_message_in(ucsi, &error, sizeof(error));
-	if (ret)
-		return ret;
+	if (cci & UCSI_CCI_BUSY) {
+		ret = ucsi_run_command(ucsi, UCSI_CANCEL, &cci, NULL, 0, false);
 
-	ret = ucsi_acknowledge(ucsi, false);
-	if (ret)
+		return ret ? ret : -EBUSY;
+	}
+
+	if (ret < 0)
 		return ret;
 
+	if (cci & UCSI_CCI_ERROR)
+		return -EIO;
+
 	switch (error) {
 	case UCSI_ERROR_INCOMPATIBLE_PARTNER:
 		return -EOPNOTSUPP;
@@ -129,7 +178,8 @@ static int ucsi_read_error(struct ucsi *ucsi, u8 connector_num)
 	return -EIO;
 }
 
-static int ucsi_exec_command(struct ucsi *ucsi, u64 cmd)
+static int ucsi_send_command_common(struct ucsi *ucsi, u64 cmd,
+				    void *data, size_t size, bool conn_ack)
 {
 	u8 connector_num;
 	u32 cci;
@@ -155,73 +205,17 @@ static int ucsi_exec_command(struct ucsi *ucsi, u64 cmd)
 		connector_num = 0;
 	}
 
-	ret = ucsi->ops->sync_control(ucsi, cmd);
-	if (ret)
-		return ret;
-
-	ret = ucsi->ops->read_cci(ucsi, &cci);
-	if (ret)
-		return ret;
-
-	if (cmd != UCSI_CANCEL && cci & UCSI_CCI_BUSY)
-		return ucsi_exec_command(ucsi, UCSI_CANCEL);
-
-	if (!(cci & UCSI_CCI_COMMAND_COMPLETE))
-		return -EIO;
-
-	if (cci & UCSI_CCI_NOT_SUPPORTED) {
-		if (ucsi_acknowledge(ucsi, false) < 0)
-			dev_err(ucsi->dev,
-				"ACK of unsupported command failed\n");
-		return -EOPNOTSUPP;
-	}
-
-	if (cci & UCSI_CCI_ERROR) {
-		/* Acknowledge the command that failed */
-		ret = ucsi_acknowledge(ucsi, false);
-		if (ret)
-			return ret;
-
-		if (cmd == UCSI_GET_ERROR_STATUS)
-			return -EIO;
-
-		return ucsi_read_error(ucsi, connector_num);
-	}
-
-	if (cmd == UCSI_CANCEL && cci & UCSI_CCI_CANCEL_COMPLETE) {
-		ret = ucsi_acknowledge(ucsi, false);
-		return ret ? ret : -EBUSY;
-	}
-
-	return UCSI_CCI_LENGTH(cci);
-}
-
-static int ucsi_send_command_common(struct ucsi *ucsi, u64 command,
-				    void *data, size_t size, bool conn_ack)
-{
-	u8 length;
-	int ret;
-
 	mutex_lock(&ucsi->ppm_lock);
 
-	ret = ucsi_exec_command(ucsi, command);
-	if (ret < 0)
-		goto out;
-
-	length = ret;
-
-	if (data) {
-		ret = ucsi_read_message_in(ucsi, data, size);
-		if (ret)
-			goto out;
+	ret = ucsi_run_command(ucsi, cmd, &cci, data, size, conn_ack);
+	if (cci & UCSI_CCI_BUSY) {
+		ret = ucsi_run_command(ucsi, UCSI_CANCEL, &cci, NULL, 0, false);
+		return ret ? ret : -EBUSY;
 	}
 
-	ret = ucsi_acknowledge(ucsi, conn_ack);
-	if (ret)
-		goto out;
+	if (cci & UCSI_CCI_ERROR)
+		return ucsi_read_error(ucsi, connector_num);
 
-	ret = length;
-out:
 	mutex_unlock(&ucsi->ppm_lock);
 	return ret;
 }