[PATCH 4/6] tty: serial: lpuart: add imx7ulp support

[Dong Aisheng]

The lpuart of imx7ulp is basically the same as ls1021a. It's also
32 bit width register, but unlike ls1021a, it's little endian.
Besides that, imx7ulp lpuart has a minor different register layout
from ls1021a that it has four extra registers (verid, param, global,
pincfg) located at the beginning of register map, which are currently
not used by the driver and less to be used later.

To ease the register difference handling, we add a reg_off member
in lpuart_soc_data structure to represent if the normal
lpuart32_{read|write} requires plus a offset to hide the issue.

Cc: Greg Kroah-Hartman <gregkh at linuxfoundation.org>
Cc: Jiri Slaby <jslaby at suse.com>
Cc: Fugang Duan <fugang.duan at nxp.com>
Cc: Stefan Agner <stefan at agner.ch>
Cc: Mingkai Hu <Mingkai.Hu at nxp.com>
Cc: Yangbo Lu <yangbo.lu at nxp.com>
Signed-off-by: Dong Aisheng <aisheng.dong at nxp.com>
---
 drivers/tty/serial/fsl_lpuart.c | 21 ++++++++++++++++++---
 1 file changed, 18 insertions(+), 3 deletions(-)

diff --git a/drivers/tty/serial/fsl_lpuart.c b/drivers/tty/serial/fsl_lpuart.c
index bddd041..1cdb3f9 100644
--- a/drivers/tty/serial/fsl_lpuart.c
+++ b/drivers/tty/serial/fsl_lpuart.c
@@ -231,7 +231,11 @@
 #define DEV_NAME	"ttyLP"
 #define UART_NR		6
 
+/* IMX lpuart has four extra unused regs located at the beginning */
+#define IMX_REG_OFF	0x10
+
 static bool lpuart_is_be;
+static u8 lpuart_reg_off;
 
 struct lpuart_port {
 	struct uart_port	port;
@@ -263,6 +267,7 @@ struct lpuart_port {
 struct lpuart_soc_data {
 	bool	is_32;
 	bool	is_be;
+	u8	reg_off;
 };
 
 static struct lpuart_soc_data vf_data = {
@@ -272,11 +277,19 @@ static struct lpuart_soc_data vf_data = {
 static struct lpuart_soc_data ls_data = {
 	.is_32 = true,
 	.is_be = true,
+	.reg_off = 0x0,
+};
+
+static struct lpuart_soc_data imx_data = {
+	.is_32 = true,
+	.is_be = false,
+	.reg_off = IMX_REG_OFF,
 };
 
 static const struct of_device_id lpuart_dt_ids[] = {
 	{ .compatible = "fsl,vf610-lpuart", .data = &vf_data, },
 	{ .compatible = "fsl,ls1021a-lpuart", .data = &ls_data, },
+	{ .compatible = "fsl,imx7ulp-lpuart", .data = &imx_data, },
 	{ /* sentinel */ }
 };
 MODULE_DEVICE_TABLE(of, lpuart_dt_ids);
@@ -286,15 +299,16 @@ static void lpuart_dma_tx_complete(void *arg);
 
 static u32 lpuart32_read(void __iomem *addr)
 {
-	return lpuart_is_be ? ioread32be(addr) : readl(addr);
+	return lpuart_is_be ? ioread32be(addr + lpuart_reg_off) :
+			      readl(addr + lpuart_reg_off);
 }
 
 static void lpuart32_write(u32 val, void __iomem *addr)
 {
 	if (lpuart_is_be)
-		iowrite32be(val, addr);
+		iowrite32be(val, addr + lpuart_reg_off);
 	else
-		writel(val, addr);
+		writel(val, addr + lpuart_reg_off);
 }
 
 static void lpuart_stop_tx(struct uart_port *port)
@@ -2008,6 +2022,7 @@ static int lpuart_probe(struct platform_device *pdev)
 	sport->port.line = ret;
 	sport->lpuart32 = sdata->is_32;
 	lpuart_is_be = sdata->is_be;
+	lpuart_reg_off = sdata->reg_off;
 
 	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
 	sport->port.membase = devm_ioremap_resource(&pdev->dev, res);
-- 
2.7.4