1 files changed, 49 insertions, 40 deletions

diff --git a/drivers/tty/serial/fsl_lpuart.c b/drivers/tty/serial/fsl_lpuart.c
index e945f41b93d4..7fd30fcc10c6 100644
--- a/drivers/tty/serial/fsl_lpuart.c
+++ b/drivers/tty/serial/fsl_lpuart.c
@@ -310,7 +310,7 @@ static const struct lpuart_soc_data ls1021a_data = {
 static const struct lpuart_soc_data ls1028a_data = {
 	.devtype = LS1028A_LPUART,
 	.iotype = UPIO_MEM32,
-	.rx_watermark = 1,
+	.rx_watermark = 0,
 };
 
 static struct lpuart_soc_data imx7ulp_data = {
@@ -858,11 +858,17 @@ static unsigned int lpuart32_tx_empty(struct uart_port *port)
 			struct lpuart_port, port);
 	unsigned long stat = lpuart32_read(port, UARTSTAT);
 	unsigned long sfifo = lpuart32_read(port, UARTFIFO);
+	unsigned long ctrl = lpuart32_read(port, UARTCTRL);
 
 	if (sport->dma_tx_in_progress)
 		return 0;
 
-	if (stat & UARTSTAT_TC && sfifo & UARTFIFO_TXEMPT)
+	/*
+	 * LPUART Transmission Complete Flag may never be set while queuing a break
+	 * character, so avoid checking for transmission complete when UARTCTRL_SBK
+	 * is asserted.
+	 */
+	if ((stat & UARTSTAT_TC && sfifo & UARTFIFO_TXEMPT) || ctrl & UARTCTRL_SBK)
 		return TIOCSER_TEMT;
 
 	return 0;
@@ -1290,7 +1296,7 @@ static inline int lpuart_start_rx_dma(struct lpuart_port *sport)
 	 * 10ms at any baud rate.
 	 */
 	sport->rx_dma_rng_buf_len = (DMA_RX_TIMEOUT * baud /  bits / 1000) * 2;
-	sport->rx_dma_rng_buf_len = (1 << (fls(sport->rx_dma_rng_buf_len) - 1));
+	sport->rx_dma_rng_buf_len = (1 << fls(sport->rx_dma_rng_buf_len));
 	if (sport->rx_dma_rng_buf_len < 16)
 		sport->rx_dma_rng_buf_len = 16;
 
@@ -1354,6 +1360,7 @@ static void lpuart_dma_rx_free(struct uart_port *port)
 	struct dma_chan *chan = sport->dma_rx_chan;
 
 	dmaengine_terminate_sync(chan);
+	del_timer_sync(&sport->lpuart_timer);
 	dma_unmap_sg(chan->device->dev, &sport->rx_sgl, 1, DMA_FROM_DEVICE);
 	kfree(sport->rx_ring.buf);
 	sport->rx_ring.tail = 0;
@@ -1399,12 +1406,12 @@ static int lpuart32_config_rs485(struct uart_port *port, struct ktermios *termio
 			struct lpuart_port, port);
 
 	unsigned long modem = lpuart32_read(&sport->port, UARTMODIR)
-				& ~(UARTMODEM_TXRTSPOL | UARTMODEM_TXRTSE);
+				& ~(UARTMODIR_TXRTSPOL | UARTMODIR_TXRTSE);
 	lpuart32_write(&sport->port, modem, UARTMODIR);
 
 	if (rs485->flags & SER_RS485_ENABLED) {
 		/* Enable auto RS-485 RTS mode */
-		modem |= UARTMODEM_TXRTSE;
+		modem |= UARTMODIR_TXRTSE;
 
 		/*
 		 * The hardware defaults to RTS logic HIGH while transfer.
@@ -1413,9 +1420,9 @@ static int lpuart32_config_rs485(struct uart_port *port, struct ktermios *termio
 		 * Note: UART is assumed to be active high.
 		 */
 		if (rs485->flags & SER_RS485_RTS_ON_SEND)
-			modem |= UARTMODEM_TXRTSPOL;
+			modem |= UARTMODIR_TXRTSPOL;
 		else if (rs485->flags & SER_RS485_RTS_AFTER_SEND)
-			modem &= ~UARTMODEM_TXRTSPOL;
+			modem &= ~UARTMODIR_TXRTSPOL;
 	}
 
 	lpuart32_write(&sport->port, modem, UARTMODIR);
@@ -1488,34 +1495,36 @@ static void lpuart_break_ctl(struct uart_port *port, int break_state)
 
 static void lpuart32_break_ctl(struct uart_port *port, int break_state)
 {
-	unsigned long temp, modem;
-	struct tty_struct *tty;
-	unsigned int cflag = 0;
-
-	tty = tty_port_tty_get(&port->state->port);
-	if (tty) {
-		cflag = tty->termios.c_cflag;
-		tty_kref_put(tty);
-	}
+	unsigned long temp;
 
-	temp = lpuart32_read(port, UARTCTRL) & ~UARTCTRL_SBK;
-	modem = lpuart32_read(port, UARTMODIR);
+	temp = lpuart32_read(port, UARTCTRL);
 
+	/*
+	 * LPUART IP now has two known bugs, one is CTS has higher priority than the
+	 * break signal, which causes the break signal sending through UARTCTRL_SBK
+	 * may impacted by the CTS input if the HW flow control is enabled. It
+	 * exists on all platforms we support in this driver.
+	 * Another bug is i.MX8QM LPUART may have an additional break character
+	 * being sent after SBK was cleared.
+	 * To avoid above two bugs, we use Transmit Data Inversion function to send
+	 * the break signal instead of UARTCTRL_SBK.
+	 */
 	if (break_state != 0) {
-		temp |= UARTCTRL_SBK;
 		/*
-		 * LPUART CTS has higher priority than SBK, need to disable CTS before
-		 * asserting SBK to avoid any interference if flow control is enabled.
+		 * Disable the transmitter to prevent any data from being sent out
+		 * during break, then invert the TX line to send break.
 		 */
-		if (cflag & CRTSCTS && modem & UARTMODIR_TXCTSE)
-			lpuart32_write(port, modem & ~UARTMODIR_TXCTSE, UARTMODIR);
+		temp &= ~UARTCTRL_TE;
+		lpuart32_write(port, temp, UARTCTRL);
+		temp |= UARTCTRL_TXINV;
+		lpuart32_write(port, temp, UARTCTRL);
 	} else {
-		/* Re-enable the CTS when break off. */
-		if (cflag & CRTSCTS && !(modem & UARTMODIR_TXCTSE))
-			lpuart32_write(port, modem | UARTMODIR_TXCTSE, UARTMODIR);
+		/* Disable the TXINV to turn off break and re-enable transmitter. */
+		temp &= ~UARTCTRL_TXINV;
+		lpuart32_write(port, temp, UARTCTRL);
+		temp |= UARTCTRL_TE;
+		lpuart32_write(port, temp, UARTCTRL);
 	}
-
-	lpuart32_write(port, temp, UARTCTRL);
 }
 
 static void lpuart_setup_watermark(struct lpuart_port *sport)
@@ -1813,7 +1822,6 @@ static int lpuart32_startup(struct uart_port *port)
 static void lpuart_dma_shutdown(struct lpuart_port *sport)
 {
 	if (sport->lpuart_dma_rx_use) {
-		del_timer_sync(&sport->lpuart_timer);
 		lpuart_dma_rx_free(&sport->port);
 		sport->lpuart_dma_rx_use = false;
 	}
@@ -1973,10 +1981,8 @@ lpuart_set_termios(struct uart_port *port, struct ktermios *termios,
 	 * Since timer function acqures sport->port.lock, need to stop before
 	 * acquring same lock because otherwise del_timer_sync() can deadlock.
 	 */
-	if (old && sport->lpuart_dma_rx_use) {
-		del_timer_sync(&sport->lpuart_timer);
+	if (old && sport->lpuart_dma_rx_use)
 		lpuart_dma_rx_free(&sport->port);
-	}
 
 	spin_lock_irqsave(&sport->port.lock, flags);
 
@@ -2210,10 +2216,8 @@ lpuart32_set_termios(struct uart_port *port, struct ktermios *termios,
 	 * Since timer function acqures sport->port.lock, need to stop before
 	 * acquring same lock because otherwise del_timer_sync() can deadlock.
 	 */
-	if (old && sport->lpuart_dma_rx_use) {
-		del_timer_sync(&sport->lpuart_timer);
+	if (old && sport->lpuart_dma_rx_use)
 		lpuart_dma_rx_free(&sport->port);
-	}
 
 	spin_lock_irqsave(&sport->port.lock, flags);
 
@@ -2240,9 +2244,15 @@ lpuart32_set_termios(struct uart_port *port, struct ktermios *termios,
 	/* update the per-port timeout */
 	uart_update_timeout(port, termios->c_cflag, baud);
 
-	/* wait transmit engin complete */
-	lpuart32_write(&sport->port, 0, UARTMODIR);
-	lpuart32_wait_bit_set(&sport->port, UARTSTAT, UARTSTAT_TC);
+	/*
+	 * LPUART Transmission Complete Flag may never be set while queuing a break
+	 * character, so skip waiting for transmission complete when UARTCTRL_SBK is
+	 * asserted.
+	 */
+	if (!(old_ctrl & UARTCTRL_SBK)) {
+		lpuart32_write(&sport->port, 0, UARTMODIR);
+		lpuart32_wait_bit_set(&sport->port, UARTSTAT, UARTSTAT_TC);
+	}
 
 	/* disable transmit and receive */
 	lpuart32_write(&sport->port, old_ctrl & ~(UARTCTRL_TE | UARTCTRL_RE),
@@ -2940,7 +2950,7 @@ static bool lpuart_uport_is_active(struct lpuart_port *sport)
 	tty = tty_port_tty_get(port);
 	if (tty) {
 		tty_dev = tty->dev;
-		may_wake = device_may_wakeup(tty_dev);
+		may_wake = tty_dev && device_may_wakeup(tty_dev);
 		tty_kref_put(tty);
 	}
 
@@ -3014,7 +3024,6 @@ static int lpuart_suspend(struct device *dev)
 			 * cannot resume as expected, hence gracefully release the
 			 * Rx DMA path before suspend and start Rx DMA path on resume.
 			 */
-			del_timer_sync(&sport->lpuart_timer);
 			lpuart_dma_rx_free(&sport->port);
 
 			/* Disable Rx DMA to use UART port as wakeup source */