tty: serial: fsl_lpuart: make rx_watermark configurable for different platforms

Add rx_watermark parameter for struct lpuart_port to make the receive
watermark configurable for different platforms.
No function changed.
Signed-off-by: Sherry Sun <sherry.sun@nxp.com>
Link: https://lore.kernel.org/r/20230130064449.9564-2-sherry.sun@nxp.comSigned-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/tty/serial/fsl_lpuart.c

@@ -262,6 +262,7 @@ struct lpuart_port {
 	unsigned int		txfifo_size;
 	unsigned int		rxfifo_size;
 
+	u8			rx_watermark;
 	bool			lpuart_dma_tx_use;
 	bool			lpuart_dma_rx_use;
 	struct dma_chan		*dma_tx_chan;
@@ -288,38 +289,45 @@ struct lpuart_soc_data {
 	enum lpuart_type devtype;
 	char iotype;
 	u8 reg_off;
+	u8 rx_watermark;
 };
 
 static const struct lpuart_soc_data vf_data = {
 	.devtype = VF610_LPUART,
 	.iotype = UPIO_MEM,
+	.rx_watermark = 1,
 };
 
 static const struct lpuart_soc_data ls1021a_data = {
 	.devtype = LS1021A_LPUART,
 	.iotype = UPIO_MEM32BE,
+	.rx_watermark = 1,
 };
 
 static const struct lpuart_soc_data ls1028a_data = {
 	.devtype = LS1028A_LPUART,
 	.iotype = UPIO_MEM32,
+	.rx_watermark = 1,
 };
 
 static struct lpuart_soc_data imx7ulp_data = {
 	.devtype = IMX7ULP_LPUART,
 	.iotype = UPIO_MEM32,
 	.reg_off = IMX_REG_OFF,
+	.rx_watermark = 1,
 };
 
 static struct lpuart_soc_data imx8qxp_data = {
 	.devtype = IMX8QXP_LPUART,
 	.iotype = UPIO_MEM32,
 	.reg_off = IMX_REG_OFF,
+	.rx_watermark = 1,
 };
 static struct lpuart_soc_data imxrt1050_data = {
 	.devtype = IMXRT1050_LPUART,
 	.iotype = UPIO_MEM32,
 	.reg_off = IMX_REG_OFF,
+	.rx_watermark = 1,
 };
 
 static const struct of_device_id lpuart_dt_ids[] = {
@@ -1520,7 +1528,7 @@ static void lpuart_setup_watermark(struct lpuart_port *sport)
 	}
 
 	writeb(0, sport->port.membase + UARTTWFIFO);
-	writeb(1, sport->port.membase + UARTRWFIFO);
+	writeb(sport->rx_watermark, sport->port.membase + UARTRWFIFO);
 
 	/* Restore cr2 */
 	writeb(cr2_saved, sport->port.membase + UARTCR2);
@@ -1555,7 +1563,8 @@ static void lpuart32_setup_watermark(struct lpuart_port *sport)
 	lpuart32_write(&sport->port, val, UARTFIFO);
 
 	/* set the watermark */
-	val = (0x1 << UARTWATER_RXWATER_OFF) | (0x0 << UARTWATER_TXWATER_OFF);
+	val = (sport->rx_watermark << UARTWATER_RXWATER_OFF) |
+	      (0x0 << UARTWATER_TXWATER_OFF);
 	lpuart32_write(&sport->port, val, UARTWATER);
 
 	/* Restore cr2 */
@@ -2731,6 +2740,7 @@ static int lpuart_probe(struct platform_device *pdev)
 	sport->port.dev = &pdev->dev;
 	sport->port.type = PORT_LPUART;
 	sport->devtype = sdata->devtype;
+	sport->rx_watermark = sdata->rx_watermark;
 	ret = platform_get_irq(pdev, 0);
 	if (ret < 0)
 		return ret;