[SRU] [jammy:linux-xilinx-zynqmp 05/14] tty: serial: uartps: Relocate cdns_uart_tx_empty to facilitate rs485

[Portia Stephens]

From: Manikanta Guntupalli <manikanta.guntupalli at amd.com>

BugLink: https://bugs.launchpad.net/bugs/2055237

Relocate cdns_uart_tx_empty function to avoid prototype statement in
rs485 changes.
Update return check with uart_tx_stopped() in cdns_uart_handle_tx().

Signed-off-by: Manikanta Guntupalli <manikanta.guntupalli at amd.com>
Link: https://lore.kernel.org/r/20240123061655.2150946-3-manikanta.guntupalli@amd.com
Signed-off-by: Greg Kroah-Hartman <gregkh at linuxfoundation.org>
(cherry picked from commit 74231ab6cc2d02303ddf1fabd878756c52f788a5)
Signed-off-by: Portia Stephens <portia.stephens at canonical.com>
---
 drivers/tty/serial/xilinx_uartps.c | 36 ++++++++++++++++--------------
 1 file changed, 19 insertions(+), 17 deletions(-)

diff --git a/drivers/tty/serial/xilinx_uartps.c b/drivers/tty/serial/xilinx_uartps.c
index 9f9fdd7424bc4..1c26ea4789f51 100644
--- a/drivers/tty/serial/xilinx_uartps.c
+++ b/drivers/tty/serial/xilinx_uartps.c
@@ -313,7 +313,22 @@ static void cdns_uart_handle_rx(void *dev_id, unsigned int isrstatus)
 }
 
 /**
- * cdns_uart_handle_tx - Handle the bytes to be Txed.
+ * cdns_uart_tx_empty -  Check whether TX is empty
+ * @port: Handle to the uart port structure
+ *
+ * Return: TIOCSER_TEMT on success, 0 otherwise
+ */
+static unsigned int cdns_uart_tx_empty(struct uart_port *port)
+{
+	unsigned int status;
+
+	status = readl(port->membase + CDNS_UART_SR);
+	status &= (CDNS_UART_SR_TXEMPTY | CDNS_UART_SR_TACTIVE);
+	return (status == CDNS_UART_SR_TXEMPTY) ? TIOCSER_TEMT : 0;
+}
+
+/**
+ * cdns_uart_handle_tx - Handle the bytes to be transmitted.
  * @dev_id: Id of the UART port
  * Return: None
  */
@@ -322,7 +337,8 @@ static void cdns_uart_handle_tx(void *dev_id)
 	struct uart_port *port = (struct uart_port *)dev_id;
 	unsigned int numbytes;
 
-	if (uart_circ_empty(&port->state->xmit)) {
+	if (uart_circ_empty(&port->state->xmit) || uart_tx_stopped(port)) {
+		/* Disable the TX Empty interrupt */
 		writel(CDNS_UART_IXR_TXEMPTY, port->membase + CDNS_UART_IDR);
 	} else {
 		numbytes = port->fifosize;
@@ -610,6 +626,7 @@ static void cdns_uart_start_tx(struct uart_port *port)
 	if (uart_circ_empty(&port->state->xmit))
 		return;
 
+	/* Clear the TX Empty interrupt */
 	writel(CDNS_UART_IXR_TXEMPTY, port->membase + CDNS_UART_ISR);
 
 	cdns_uart_handle_tx(port);
@@ -649,21 +666,6 @@ static void cdns_uart_stop_rx(struct uart_port *port)
 	writel(regval, port->membase + CDNS_UART_CR);
 }
 
-/**
- * cdns_uart_tx_empty -  Check whether TX is empty
- * @port: Handle to the uart port structure
- *
- * Return: TIOCSER_TEMT on success, 0 otherwise
- */
-static unsigned int cdns_uart_tx_empty(struct uart_port *port)
-{
-	unsigned int status;
-
-	status = readl(port->membase + CDNS_UART_SR) &
-		       (CDNS_UART_SR_TXEMPTY | CDNS_UART_SR_TACTIVE);
-	return (status == CDNS_UART_SR_TXEMPTY) ? TIOCSER_TEMT : 0;
-}
-
 /**
  * cdns_uart_break_ctl - Based on the input ctl we have to start or stop
  *			transmitting char breaks
-- 
2.34.1