linux-kernel - [PATCH 2/2] tty: serial: fsl_lpuart: improve lpuart32 registers clearing when shutdown

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Message-Id: <20221109104515.17266-3-sherry.sun@nxp.com>
Date:   Wed,  9 Nov 2022 18:45:15 +0800
From:   Sherry Sun <sherry.sun@....com>
To:     gregkh@...uxfoundation.org, jirislaby@...nel.org
Cc:     linux-serial@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-imx@....com
Subject: [PATCH 2/2] tty: serial: fsl_lpuart: improve lpuart32 registers clearing when shutdown

Need to clear the UARTSTAT and UARTMODIR registers when shutdown the
uart port, also clear the Rx/Tx DMA enable bits and loopback
configuration bit.

Signed-off-by: Sherry Sun <sherry.sun@....com>
---
 drivers/tty/serial/fsl_lpuart.c | 13 ++++++++++++-
 1 file changed, 12 insertions(+), 1 deletion(-)

diff --git a/drivers/tty/serial/fsl_lpuart.c b/drivers/tty/serial/fsl_lpuart.c
index f5a0a14fa366..43d9d6a6e94a 100644
--- a/drivers/tty/serial/fsl_lpuart.c
+++ b/drivers/tty/serial/fsl_lpuart.c
@@ -1771,11 +1771,22 @@ static void lpuart32_shutdown(struct uart_port *port)
 
 	spin_lock_irqsave(&port->lock, flags);
 
+	/* clear statue */
+	temp = lpuart32_read(&sport->port, UARTSTAT);
+	lpuart32_write(&sport->port, temp, UARTSTAT);
+
+	/* disable Rx/Tx DMA */
+	temp = lpuart32_read(port, UARTBAUD);
+	temp &= ~(UARTBAUD_TDMAE | UARTBAUD_RDMAE);
+	lpuart32_write(port, temp, UARTBAUD);
+
 	/* disable Rx/Tx and interrupts */
 	temp = lpuart32_read(port, UARTCTRL);
 	temp &= ~(UARTCTRL_TE | UARTCTRL_RE | UARTCTRL_ILIE |
-			UARTCTRL_TIE | UARTCTRL_TCIE | UARTCTRL_RIE);
+			UARTCTRL_TIE | UARTCTRL_TCIE | UARTCTRL_RIE |
+			UARTCTRL_LOOPS);
 	lpuart32_write(port, temp, UARTCTRL);
+	lpuart32_write(port, 0, UARTMODIR);
 
 	spin_unlock_irqrestore(&port->lock, flags);
 
-- 
2.17.1