[PATCH] serial: uartlite: Add support to work with any endianness

[Michal Simek]

From: T Karthik Reddy <t.karthik.reddy at xilinx.com>

This endinness changes are taken from linux uartlite driver.
Reset TX fifo in control register and check TX fifo empty
flag in lower byte of the status register to detect if it
is a little endian system. Based on this check, program the
registers with le32 or be32 through out the driver.

Signed-off-by: T Karthik Reddy <t.karthik.reddy at xilinx.com>
Signed-off-by: Ashok Reddy Soma <ashok.reddy.soma at xilinx.com>
Signed-off-by: Michal Simek <michal.simek at xilinx.com>
---

 drivers/serial/serial_xuartlite.c | 74 ++++++++++++++++++++++++++-----
 1 file changed, 64 insertions(+), 10 deletions(-)

diff --git a/drivers/serial/serial_xuartlite.c b/drivers/serial/serial_xuartlite.c
index 5116d13751de..e16642504b16 100644
--- a/drivers/serial/serial_xuartlite.c
+++ b/drivers/serial/serial_xuartlite.c
@@ -32,17 +32,64 @@ struct uartlite {
 
 struct uartlite_platdata {
 	struct uartlite *regs;
+	const struct uartlite_reg_ops *reg_ops;
 };
 
+struct uartlite_reg_ops {
+	u32 (*in)(void __iomem *addr);
+	void (*out)(u32 val, void __iomem *addr);
+};
+
+static u32 uartlite_inle32(void __iomem *addr)
+{
+	return in_le32(addr);
+}
+
+static void uartlite_outle32(u32 val, void __iomem *addr)
+{
+	out_le32(addr, val);
+}
+
+static const struct uartlite_reg_ops uartlite_le = {
+	.in = uartlite_inle32,
+	.out = uartlite_outle32,
+};
+
+static u32 uartlite_inbe32(void __iomem *addr)
+{
+	return in_be32(addr);
+}
+
+static void uartlite_outbe32(u32 val, void __iomem *addr)
+{
+	out_be32(addr, val);
+}
+
+static const struct uartlite_reg_ops uartlite_be = {
+	.in = uartlite_inbe32,
+	.out = uartlite_outbe32,
+};
+
+static u32 uart_in32(void __iomem *addr, struct uartlite_platdata *plat)
+{
+	return plat->reg_ops->in(addr);
+}
+
+static void uart_out32(void __iomem *addr, u32 val,
+		       struct uartlite_platdata *plat)
+{
+	plat->reg_ops->out(val, addr);
+}
+
 static int uartlite_serial_putc(struct udevice *dev, const char ch)
 {
 	struct uartlite_platdata *plat = dev_get_platdata(dev);
 	struct uartlite *regs = plat->regs;
 
-	if (in_be32(&regs->status) & SR_TX_FIFO_FULL)
+	if (uart_in32(&regs->status, plat) & SR_TX_FIFO_FULL)
 		return -EAGAIN;
 
-	out_be32(&regs->tx_fifo, ch & 0xff);
+	uart_out32(&regs->tx_fifo, ch & 0xff, plat);
 
 	return 0;
 }
@@ -52,10 +99,10 @@ static int uartlite_serial_getc(struct udevice *dev)
 	struct uartlite_platdata *plat = dev_get_platdata(dev);
 	struct uartlite *regs = plat->regs;
 
-	if (!(in_be32(&regs->status) & SR_RX_FIFO_VALID_DATA))
+	if (!(uart_in32(&regs->status, plat) & SR_RX_FIFO_VALID_DATA))
 		return -EAGAIN;
 
-	return in_be32(&regs->rx_fifo) & 0xff;
+	return uart_in32(&regs->rx_fifo, plat) & 0xff;
 }
 
 static int uartlite_serial_pending(struct udevice *dev, bool input)
@@ -64,19 +111,26 @@ static int uartlite_serial_pending(struct udevice *dev, bool input)
 	struct uartlite *regs = plat->regs;
 
 	if (input)
-		return in_be32(&regs->status) & SR_RX_FIFO_VALID_DATA;
+		return uart_in32(&regs->status, plat) & SR_RX_FIFO_VALID_DATA;
 
-	return !(in_be32(&regs->status) & SR_TX_FIFO_EMPTY);
+	return !(uart_in32(&regs->status, plat) & SR_TX_FIFO_EMPTY);
 }
 
 static int uartlite_serial_probe(struct udevice *dev)
 {
 	struct uartlite_platdata *plat = dev_get_platdata(dev);
 	struct uartlite *regs = plat->regs;
-
-	out_be32(&regs->control, 0);
-	out_be32(&regs->control, ULITE_CONTROL_RST_RX | ULITE_CONTROL_RST_TX);
-	in_be32(&regs->control);
+	int ret;
+
+	plat->reg_ops = &uartlite_be;
+	ret = uart_in32(&regs->control, plat);
+	uart_out32(&regs->control, 0, plat);
+	uart_out32(&regs->control,
+		   ULITE_CONTROL_RST_RX | ULITE_CONTROL_RST_TX, plat);
+	ret = uart_in32(&regs->status, plat);
+	/* Endianness detection */
+	if ((ret & SR_TX_FIFO_EMPTY) != SR_TX_FIFO_EMPTY)
+		plat->reg_ops = &uartlite_le;
 
 	return 0;
 }
-- 
2.28.0