tty: serial: Add RDA8810PL UART driver

Add UART driver for RDA Micro RDA8810PL SoC.

Signed-off-by: Andreas Färber <afaerber@suse.de>
Signed-off-by: Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>
Reviewed-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Acked-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Olof Johansson <olof@lixom.net>

3 files changed, 851 insertions, 0 deletions

diff --git a/drivers/tty/serial/Kconfig b/drivers/tty/serial/Kconfig
index 32886c304641..67b9bf3b500e 100644
--- a/drivers/tty/serial/Kconfig
+++ b/drivers/tty/serial/Kconfig
@@ -1529,6 +1529,25 @@ config SERIAL_OWL_CONSOLE
 	  Say 'Y' here if you wish to use Actions Semiconductor S500/S900 UART
 	  as the system console.
 
+config SERIAL_RDA
+	bool "RDA Micro serial port support"
+	depends on ARCH_RDA || COMPILE_TEST
+	select SERIAL_CORE
+	help
+	  This driver is for RDA8810PL SoC's UART.
+	  Say 'Y' here if you wish to use the on-board serial port.
+	  Otherwise, say 'N'.
+
+config SERIAL_RDA_CONSOLE
+	bool "Console on RDA Micro serial port"
+	depends on SERIAL_RDA=y
+	select SERIAL_CORE_CONSOLE
+	select SERIAL_EARLYCON
+	default y
+	help
+	  Say 'Y' here if you wish to use the RDA8810PL UART as the system
+	  console. Only earlycon is implemented currently.
+
 endmenu
 
 config SERIAL_MCTRL_GPIO
diff --git a/drivers/tty/serial/Makefile b/drivers/tty/serial/Makefile
index daac675612df..8c303736b7e8 100644
--- a/drivers/tty/serial/Makefile
+++ b/drivers/tty/serial/Makefile
@@ -89,6 +89,7 @@ obj-$(CONFIG_SERIAL_MVEBU_UART)	+= mvebu-uart.o
 obj-$(CONFIG_SERIAL_PIC32)	+= pic32_uart.o
 obj-$(CONFIG_SERIAL_MPS2_UART)	+= mps2-uart.o
 obj-$(CONFIG_SERIAL_OWL)	+= owl-uart.o
+obj-$(CONFIG_SERIAL_RDA)	+= rda-uart.o
 
 # GPIOLIB helpers for modem control lines
 obj-$(CONFIG_SERIAL_MCTRL_GPIO)	+= serial_mctrl_gpio.o
diff --git a/drivers/tty/serial/rda-uart.c b/drivers/tty/serial/rda-uart.c
new file mode 100644
index 000000000000..284623eefaeb
--- /dev/null
+++ b/drivers/tty/serial/rda-uart.c
@@ -0,0 +1,831 @@
+// SPDX-License-Identifier: GPL-2.0+
+/*
+ * RDA8810PL serial device driver
+ *
+ * Copyright RDA Microelectronics Company Limited
+ * Copyright (c) 2017 Andreas Färber
+ * Copyright (c) 2018 Manivannan Sadhasivam
+ */
+
+#include <linux/clk.h>
+#include <linux/console.h>
+#include <linux/delay.h>
+#include <linux/io.h>
+#include <linux/module.h>
+#include <linux/of.h>
+#include <linux/platform_device.h>
+#include <linux/serial.h>
+#include <linux/serial_core.h>
+#include <linux/tty.h>
+#include <linux/tty_flip.h>
+
+#define RDA_UART_PORT_NUM 3
+#define RDA_UART_DEV_NAME "ttyRDA"
+
+#define RDA_UART_CTRL		0x00
+#define RDA_UART_STATUS		0x04
+#define RDA_UART_RXTX_BUFFER	0x08
+#define RDA_UART_IRQ_MASK	0x0c
+#define RDA_UART_IRQ_CAUSE	0x10
+#define RDA_UART_IRQ_TRIGGERS	0x14
+#define RDA_UART_CMD_SET	0x18
+#define RDA_UART_CMD_CLR	0x1c
+
+/* UART_CTRL Bits */
+#define RDA_UART_ENABLE			BIT(0)
+#define RDA_UART_DBITS_8		BIT(1)
+#define RDA_UART_TX_SBITS_2		BIT(2)
+#define RDA_UART_PARITY_EN		BIT(3)
+#define RDA_UART_PARITY(x)		(((x) & 0x3) << 4)
+#define RDA_UART_PARITY_ODD		RDA_UART_PARITY(0)
+#define RDA_UART_PARITY_EVEN		RDA_UART_PARITY(1)
+#define RDA_UART_PARITY_SPACE		RDA_UART_PARITY(2)
+#define RDA_UART_PARITY_MARK		RDA_UART_PARITY(3)
+#define RDA_UART_DIV_MODE		BIT(20)
+#define RDA_UART_IRDA_EN		BIT(21)
+#define RDA_UART_DMA_EN			BIT(22)
+#define RDA_UART_FLOW_CNT_EN		BIT(23)
+#define RDA_UART_LOOP_BACK_EN		BIT(24)
+#define RDA_UART_RX_LOCK_ERR		BIT(25)
+#define RDA_UART_RX_BREAK_LEN(x)	(((x) & 0xf) << 28)
+
+/* UART_STATUS Bits */
+#define RDA_UART_RX_FIFO(x)		(((x) & 0x7f) << 0)
+#define RDA_UART_RX_FIFO_MASK		(0x7f << 0)
+#define RDA_UART_TX_FIFO(x)		(((x) & 0x1f) << 8)
+#define RDA_UART_TX_FIFO_MASK		(0x1f << 8)
+#define RDA_UART_TX_ACTIVE		BIT(14)
+#define RDA_UART_RX_ACTIVE		BIT(15)
+#define RDA_UART_RX_OVERFLOW_ERR	BIT(16)
+#define RDA_UART_TX_OVERFLOW_ERR	BIT(17)
+#define RDA_UART_RX_PARITY_ERR		BIT(18)
+#define RDA_UART_RX_FRAMING_ERR		BIT(19)
+#define RDA_UART_RX_BREAK_INT		BIT(20)
+#define RDA_UART_DCTS			BIT(24)
+#define RDA_UART_CTS			BIT(25)
+#define RDA_UART_DTR			BIT(28)
+#define RDA_UART_CLK_ENABLED		BIT(31)
+
+/* UART_RXTX_BUFFER Bits */
+#define RDA_UART_RX_DATA(x)		(((x) & 0xff) << 0)
+#define RDA_UART_TX_DATA(x)		(((x) & 0xff) << 0)
+
+/* UART_IRQ_MASK Bits */
+#define RDA_UART_TX_MODEM_STATUS	BIT(0)
+#define RDA_UART_RX_DATA_AVAILABLE	BIT(1)
+#define RDA_UART_TX_DATA_NEEDED		BIT(2)
+#define RDA_UART_RX_TIMEOUT		BIT(3)
+#define RDA_UART_RX_LINE_ERR		BIT(4)
+#define RDA_UART_TX_DMA_DONE		BIT(5)
+#define RDA_UART_RX_DMA_DONE		BIT(6)
+#define RDA_UART_RX_DMA_TIMEOUT		BIT(7)
+#define RDA_UART_DTR_RISE		BIT(8)
+#define RDA_UART_DTR_FALL		BIT(9)
+
+/* UART_IRQ_CAUSE Bits */
+#define RDA_UART_TX_MODEM_STATUS_U	BIT(16)
+#define RDA_UART_RX_DATA_AVAILABLE_U	BIT(17)
+#define RDA_UART_TX_DATA_NEEDED_U	BIT(18)
+#define RDA_UART_RX_TIMEOUT_U		BIT(19)
+#define RDA_UART_RX_LINE_ERR_U		BIT(20)
+#define RDA_UART_TX_DMA_DONE_U		BIT(21)
+#define RDA_UART_RX_DMA_DONE_U		BIT(22)
+#define RDA_UART_RX_DMA_TIMEOUT_U	BIT(23)
+#define RDA_UART_DTR_RISE_U		BIT(24)
+#define RDA_UART_DTR_FALL_U		BIT(25)
+
+/* UART_TRIGGERS Bits */
+#define RDA_UART_RX_TRIGGER(x)		(((x) & 0x1f) << 0)
+#define RDA_UART_TX_TRIGGER(x)		(((x) & 0xf) << 8)
+#define RDA_UART_AFC_LEVEL(x)		(((x) & 0x1f) << 16)
+
+/* UART_CMD_SET Bits */
+#define RDA_UART_RI			BIT(0)
+#define RDA_UART_DCD			BIT(1)
+#define RDA_UART_DSR			BIT(2)
+#define RDA_UART_TX_BREAK_CONTROL	BIT(3)
+#define RDA_UART_TX_FINISH_N_WAIT	BIT(4)
+#define RDA_UART_RTS			BIT(5)
+#define RDA_UART_RX_FIFO_RESET		BIT(6)
+#define RDA_UART_TX_FIFO_RESET		BIT(7)
+
+#define RDA_UART_TX_FIFO_SIZE	16
+
+static struct uart_driver rda_uart_driver;
+
+struct rda_uart_port {
+	struct uart_port port;
+	struct clk *clk;
+};
+
+#define to_rda_uart_port(port) container_of(port, struct rda_uart_port, port)
+
+static struct rda_uart_port *rda_uart_ports[RDA_UART_PORT_NUM];
+
+static inline void rda_uart_write(struct uart_port *port, u32 val,
+				  unsigned int off)
+{
+	writel(val, port->membase + off);
+}
+
+static inline u32 rda_uart_read(struct uart_port *port, unsigned int off)
+{
+	return readl(port->membase + off);
+}
+
+static unsigned int rda_uart_tx_empty(struct uart_port *port)
+{
+	unsigned long flags;
+	unsigned int ret;
+	u32 val;
+
+	spin_lock_irqsave(&port->lock, flags);
+
+	val = rda_uart_read(port, RDA_UART_STATUS);
+	ret = (val & RDA_UART_TX_FIFO_MASK) ? TIOCSER_TEMT : 0;
+
+	spin_unlock_irqrestore(&port->lock, flags);
+
+	return ret;
+}
+
+static unsigned int rda_uart_get_mctrl(struct uart_port *port)
+{
+	unsigned int mctrl = 0;
+	u32 cmd_set, status;
+
+	cmd_set = rda_uart_read(port, RDA_UART_CMD_SET);
+	status = rda_uart_read(port, RDA_UART_STATUS);
+	if (cmd_set & RDA_UART_RTS)
+		mctrl |= TIOCM_RTS;
+	if (!(status & RDA_UART_CTS))
+		mctrl |= TIOCM_CTS;
+
+	return mctrl;
+}
+
+static void rda_uart_set_mctrl(struct uart_port *port, unsigned int mctrl)
+{
+	u32 val;
+
+	if (mctrl & TIOCM_RTS) {
+		val = rda_uart_read(port, RDA_UART_CMD_SET);
+		rda_uart_write(port, (val | RDA_UART_RTS), RDA_UART_CMD_SET);
+	} else {
+		/* Clear RTS to stop to receive. */
+		val = rda_uart_read(port, RDA_UART_CMD_CLR);
+		rda_uart_write(port, (val | RDA_UART_RTS), RDA_UART_CMD_CLR);
+	}
+
+	val = rda_uart_read(port, RDA_UART_CTRL);
+
+	if (mctrl & TIOCM_LOOP)
+		val |= RDA_UART_LOOP_BACK_EN;
+	else
+		val &= ~RDA_UART_LOOP_BACK_EN;
+
+	rda_uart_write(port, val, RDA_UART_CTRL);
+}
+
+static void rda_uart_stop_tx(struct uart_port *port)
+{
+	u32 val;
+
+	val = rda_uart_read(port, RDA_UART_IRQ_MASK);
+	val &= ~RDA_UART_TX_DATA_NEEDED;
+	rda_uart_write(port, val, RDA_UART_IRQ_MASK);
+
+	val = rda_uart_read(port, RDA_UART_CMD_SET);
+	val |= RDA_UART_TX_FIFO_RESET;
+	rda_uart_write(port, val, RDA_UART_CMD_SET);
+}
+
+static void rda_uart_stop_rx(struct uart_port *port)
+{
+	u32 val;
+
+	val = rda_uart_read(port, RDA_UART_IRQ_MASK);
+	val &= ~(RDA_UART_RX_DATA_AVAILABLE | RDA_UART_RX_TIMEOUT);
+	rda_uart_write(port, val, RDA_UART_IRQ_MASK);
+
+	/* Read Rx buffer before reset to avoid Rx timeout interrupt */
+	val = rda_uart_read(port, RDA_UART_RXTX_BUFFER);
+
+	val = rda_uart_read(port, RDA_UART_CMD_SET);
+	val |= RDA_UART_RX_FIFO_RESET;
+	rda_uart_write(port, val, RDA_UART_CMD_SET);
+}
+
+static void rda_uart_start_tx(struct uart_port *port)
+{
+	u32 val;
+
+	if (uart_tx_stopped(port)) {
+		rda_uart_stop_tx(port);
+		return;
+	}
+
+	val = rda_uart_read(port, RDA_UART_IRQ_MASK);
+	val |= RDA_UART_TX_DATA_NEEDED;
+	rda_uart_write(port, val, RDA_UART_IRQ_MASK);
+}
+
+static void rda_uart_change_baudrate(struct rda_uart_port *rda_port,
+				     unsigned long baud)
+{
+	clk_set_rate(rda_port->clk, baud * 8);
+}
+
+static void rda_uart_set_termios(struct uart_port *port,
+				 struct ktermios *termios,
+				 struct ktermios *old)
+{
+	struct rda_uart_port *rda_port = to_rda_uart_port(port);
+	unsigned long flags;
+	unsigned int ctrl, cmd_set, cmd_clr, triggers;
+	unsigned int baud;
+	u32 irq_mask;
+
+	spin_lock_irqsave(&port->lock, flags);
+
+	baud = uart_get_baud_rate(port, termios, old, 9600, port->uartclk / 4);
+	rda_uart_change_baudrate(rda_port, baud);
+
+	ctrl = rda_uart_read(port, RDA_UART_CTRL);
+	cmd_set = rda_uart_read(port, RDA_UART_CMD_SET);
+	cmd_clr = rda_uart_read(port, RDA_UART_CMD_CLR);
+
+	switch (termios->c_cflag & CSIZE) {
+	case CS5:
+	case CS6:
+		dev_warn(port->dev, "bit size not supported, using 7 bits\n");
+		/* Fall through */
+	case CS7:
+		ctrl &= ~RDA_UART_DBITS_8;
+		break;
+	default:
+		ctrl |= RDA_UART_DBITS_8;
+		break;
+	}
+
+	/* stop bits */
+	if (termios->c_cflag & CSTOPB)
+		ctrl |= RDA_UART_TX_SBITS_2;
+	else
+		ctrl &= ~RDA_UART_TX_SBITS_2;
+
+	/* parity check */
+	if (termios->c_cflag & PARENB) {
+		ctrl |= RDA_UART_PARITY_EN;
+
+		/* Mark or Space parity */
+		if (termios->c_cflag & CMSPAR) {
+			if (termios->c_cflag & PARODD)
+				ctrl |= RDA_UART_PARITY_MARK;
+			else
+				ctrl |= RDA_UART_PARITY_SPACE;
+		} else if (termios->c_cflag & PARODD) {
+			ctrl |= RDA_UART_PARITY_ODD;
+		} else {
+			ctrl |= RDA_UART_PARITY_EVEN;
+		}
+	} else {
+		ctrl &= ~RDA_UART_PARITY_EN;
+	}
+
+	/* Hardware handshake (RTS/CTS) */
+	if (termios->c_cflag & CRTSCTS) {
+		ctrl   |= RDA_UART_FLOW_CNT_EN;
+		cmd_set |= RDA_UART_RTS;
+	} else {
+		ctrl   &= ~RDA_UART_FLOW_CNT_EN;
+		cmd_clr |= RDA_UART_RTS;
+	}
+
+	ctrl |= RDA_UART_ENABLE;
+	ctrl &= ~RDA_UART_DMA_EN;
+
+	triggers  = (RDA_UART_AFC_LEVEL(20) | RDA_UART_RX_TRIGGER(16));
+	irq_mask = rda_uart_read(port, RDA_UART_IRQ_MASK);
+	rda_uart_write(port, 0, RDA_UART_IRQ_MASK);
+
+	rda_uart_write(port, triggers, RDA_UART_IRQ_TRIGGERS);
+	rda_uart_write(port, ctrl, RDA_UART_CTRL);
+	rda_uart_write(port, cmd_set, RDA_UART_CMD_SET);
+	rda_uart_write(port, cmd_clr, RDA_UART_CMD_CLR);
+
+	rda_uart_write(port, irq_mask, RDA_UART_IRQ_MASK);
+
+	/* Don't rewrite B0 */
+	if (tty_termios_baud_rate(termios))
+		tty_termios_encode_baud_rate(termios, baud, baud);
+
+	/* update the per-port timeout */
+	uart_update_timeout(port, termios->c_cflag, baud);
+
+	spin_unlock_irqrestore(&port->lock, flags);
+}
+
+static void rda_uart_send_chars(struct uart_port *port)
+{
+	struct circ_buf *xmit = &port->state->xmit;
+	unsigned int ch;
+	u32 val;
+
+	if (uart_tx_stopped(port))
+		return;
+
+	if (port->x_char) {
+		while (!(rda_uart_read(port, RDA_UART_STATUS) &
+			 RDA_UART_TX_FIFO_MASK))
+			cpu_relax();
+
+		rda_uart_write(port, port->x_char, RDA_UART_RXTX_BUFFER);
+		port->icount.tx++;
+		port->x_char = 0;
+	}
+
+	while (rda_uart_read(port, RDA_UART_STATUS) & RDA_UART_TX_FIFO_MASK) {
+		if (uart_circ_empty(xmit))
+			break;
+
+		ch = xmit->buf[xmit->tail];
+		rda_uart_write(port, ch, RDA_UART_RXTX_BUFFER);
+		xmit->tail = (xmit->tail + 1) & (SERIAL_XMIT_SIZE - 1);
+		port->icount.tx++;
+	}
+
+	if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
+		uart_write_wakeup(port);
+
+	if (!uart_circ_empty(xmit)) {
+		/* Re-enable Tx FIFO interrupt */
+		val = rda_uart_read(port, RDA_UART_IRQ_MASK);
+		val |= RDA_UART_TX_DATA_NEEDED;
+		rda_uart_write(port, val, RDA_UART_IRQ_MASK);
+	}
+}
+
+static void rda_uart_receive_chars(struct uart_port *port)
+{
+	u32 status, val;
+
+	status = rda_uart_read(port, RDA_UART_STATUS);
+	while ((status & RDA_UART_RX_FIFO_MASK)) {
+		char flag = TTY_NORMAL;
+
+		if (status & RDA_UART_RX_PARITY_ERR) {
+			port->icount.parity++;
+			flag = TTY_PARITY;
+		}
+
+		if (status & RDA_UART_RX_FRAMING_ERR) {
+			port->icount.frame++;
+			flag = TTY_FRAME;
+		}
+
+		if (status & RDA_UART_RX_OVERFLOW_ERR) {
+			port->icount.overrun++;
+			flag = TTY_OVERRUN;
+		}
+
+		val = rda_uart_read(port, RDA_UART_RXTX_BUFFER);
+		val &= 0xff;
+
+		port->icount.rx++;
+		tty_insert_flip_char(&port->state->port, val, flag);
+
+		status = rda_uart_read(port, RDA_UART_STATUS);
+	}
+
+	spin_unlock(&port->lock);
+	tty_flip_buffer_push(&port->state->port);
+	spin_lock(&port->lock);
+}
+
+static irqreturn_t rda_interrupt(int irq, void *dev_id)
+{
+	struct uart_port *port = dev_id;
+	unsigned long flags;
+	u32 val, irq_mask;
+
+	spin_lock_irqsave(&port->lock, flags);
+
+	/* Clear IRQ cause */
+	val = rda_uart_read(port, RDA_UART_IRQ_CAUSE);
+	rda_uart_write(port, val, RDA_UART_IRQ_CAUSE);
+
+	if (val & (RDA_UART_RX_DATA_AVAILABLE | RDA_UART_RX_TIMEOUT))
+		rda_uart_receive_chars(port);
+
+	if (val & (RDA_UART_TX_DATA_NEEDED)) {
+		irq_mask = rda_uart_read(port, RDA_UART_IRQ_MASK);
+		irq_mask &= ~RDA_UART_TX_DATA_NEEDED;
+		rda_uart_write(port, irq_mask, RDA_UART_IRQ_MASK);
+
+		rda_uart_send_chars(port);
+	}
+
+	spin_unlock_irqrestore(&port->lock, flags);
+
+	return IRQ_HANDLED;
+}
+
+static int rda_uart_startup(struct uart_port *port)
+{
+	unsigned long flags;
+	int ret;
+	u32 val;
+
+	spin_lock_irqsave(&port->lock, flags);
+	rda_uart_write(port, 0, RDA_UART_IRQ_MASK);
+	spin_unlock_irqrestore(&port->lock, flags);
+
+	ret = request_irq(port->irq, rda_interrupt, IRQF_NO_SUSPEND,
+			  "rda-uart", port);
+	if (ret)
+		return ret;
+
+	spin_lock_irqsave(&port->lock, flags);
+
+	val = rda_uart_read(port, RDA_UART_CTRL);
+	val |= RDA_UART_ENABLE;
+	rda_uart_write(port, val, RDA_UART_CTRL);
+
+	/* enable rx interrupt */
+	val = rda_uart_read(port, RDA_UART_IRQ_MASK);
+	val |= (RDA_UART_RX_DATA_AVAILABLE | RDA_UART_RX_TIMEOUT);
+	rda_uart_write(port, val, RDA_UART_IRQ_MASK);
+
+	spin_unlock_irqrestore(&port->lock, flags);
+
+	return 0;
+}
+
+static void rda_uart_shutdown(struct uart_port *port)
+{
+	unsigned long flags;
+	u32 val;
+
+	spin_lock_irqsave(&port->lock, flags);
+
+	rda_uart_stop_tx(port);
+	rda_uart_stop_rx(port);
+
+	val = rda_uart_read(port, RDA_UART_CTRL);
+	val &= ~RDA_UART_ENABLE;
+	rda_uart_write(port, val, RDA_UART_CTRL);
+
+	spin_unlock_irqrestore(&port->lock, flags);
+}
+
+static const char *rda_uart_type(struct uart_port *port)
+{
+	return (port->type == PORT_RDA) ? "rda-uart" : NULL;
+}
+
+static int rda_uart_request_port(struct uart_port *port)
+{
+	struct platform_device *pdev = to_platform_device(port->dev);
+	struct resource *res;
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	if (!res)
+		return -ENXIO;
+
+	if (!devm_request_mem_region(port->dev, port->mapbase,
+				     resource_size(res), dev_name(port->dev)))
+		return -EBUSY;
+
+	if (port->flags & UPF_IOREMAP) {
+		port->membase = devm_ioremap_nocache(port->dev, port->mapbase,
+						     resource_size(res));
+		if (!port->membase)
+			return -EBUSY;
+	}
+
+	return 0;
+}
+
+static void rda_uart_config_port(struct uart_port *port, int flags)
+{
+	unsigned long irq_flags;
+
+	if (flags & UART_CONFIG_TYPE) {
+		port->type = PORT_RDA;
+		rda_uart_request_port(port);
+	}
+
+	spin_lock_irqsave(&port->lock, irq_flags);
+
+	/* Clear mask, so no surprise interrupts. */
+	rda_uart_write(port, 0, RDA_UART_IRQ_MASK);
+
+	/* Clear status register */
+	rda_uart_write(port, 0, RDA_UART_STATUS);
+
+	spin_unlock_irqrestore(&port->lock, irq_flags);
+}
+
+static void rda_uart_release_port(struct uart_port *port)
+{
+	struct platform_device *pdev = to_platform_device(port->dev);
+	struct resource *res;
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	if (!res)
+		return;
+
+	if (port->flags & UPF_IOREMAP) {
+		devm_release_mem_region(port->dev, port->mapbase,
+					resource_size(res));
+		devm_iounmap(port->dev, port->membase);
+		port->membase = NULL;
+	}
+}
+
+static int rda_uart_verify_port(struct uart_port *port,
+				struct serial_struct *ser)
+{
+	if (port->type != PORT_RDA)
+		return -EINVAL;
+
+	if (port->irq != ser->irq)
+		return -EINVAL;
+
+	return 0;
+}
+
+static const struct uart_ops rda_uart_ops = {
+	.tx_empty       = rda_uart_tx_empty,
+	.get_mctrl      = rda_uart_get_mctrl,
+	.set_mctrl      = rda_uart_set_mctrl,
+	.start_tx       = rda_uart_start_tx,
+	.stop_tx        = rda_uart_stop_tx,
+	.stop_rx        = rda_uart_stop_rx,
+	.startup        = rda_uart_startup,
+	.shutdown       = rda_uart_shutdown,
+	.set_termios    = rda_uart_set_termios,
+	.type           = rda_uart_type,
+	.request_port	= rda_uart_request_port,
+	.release_port	= rda_uart_release_port,
+	.config_port	= rda_uart_config_port,
+	.verify_port	= rda_uart_verify_port,
+};
+
+#ifdef CONFIG_SERIAL_RDA_CONSOLE
+
+static void rda_console_putchar(struct uart_port *port, int ch)
+{
+	if (!port->membase)
+		return;
+
+	while (!(rda_uart_read(port, RDA_UART_STATUS) & RDA_UART_TX_FIFO_MASK))
+		cpu_relax();
+
+	rda_uart_write(port, ch, RDA_UART_RXTX_BUFFER);
+}
+
+static void rda_uart_port_write(struct uart_port *port, const char *s,
+				u_int count)
+{
+	u32 old_irq_mask;
+	unsigned long flags;
+	int locked;
+
+	local_irq_save(flags);
+
+	if (port->sysrq) {
+		locked = 0;
+	} else if (oops_in_progress) {
+		locked = spin_trylock(&port->lock);
+	} else {
+		spin_lock(&port->lock);
+		locked = 1;
+	}
+
+	old_irq_mask = rda_uart_read(port, RDA_UART_IRQ_MASK);
+	rda_uart_write(port, 0, RDA_UART_IRQ_MASK);
+
+	uart_console_write(port, s, count, rda_console_putchar);
+
+	/* wait until all contents have been sent out */
+	while (!(rda_uart_read(port, RDA_UART_STATUS) & RDA_UART_TX_FIFO_MASK))
+		cpu_relax();
+
+	rda_uart_write(port, old_irq_mask, RDA_UART_IRQ_MASK);
+
+	if (locked)
+		spin_unlock(&port->lock);
+
+	local_irq_restore(flags);
+}
+
+static void rda_uart_console_write(struct console *co, const char *s,
+				   u_int count)
+{
+	struct rda_uart_port *rda_port;
+
+	rda_port = rda_uart_ports[co->index];
+	if (!rda_port)
+		return;
+
+	rda_uart_port_write(&rda_port->port, s, count);
+}
+
+static int rda_uart_console_setup(struct console *co, char *options)
+{
+	struct rda_uart_port *rda_port;
+	int baud = 921600;
+	int bits = 8;
+	int parity = 'n';
+	int flow = 'n';
+
+	if (co->index < 0 || co->index >= RDA_UART_PORT_NUM)
+		return -EINVAL;
+
+	rda_port = rda_uart_ports[co->index];
+	if (!rda_port || !rda_port->port.membase)
+		return -ENODEV;
+
+	if (options)
+		uart_parse_options(options, &baud, &parity, &bits, &flow);
+
+	return uart_set_options(&rda_port->port, co, baud, parity, bits, flow);
+}
+
+static struct console rda_uart_console = {
+	.name = RDA_UART_DEV_NAME,
+	.write = rda_uart_console_write,
+	.device = uart_console_device,
+	.setup = rda_uart_console_setup,
+	.flags = CON_PRINTBUFFER,
+	.index = -1,
+	.data = &rda_uart_driver,
+};
+
+static int __init rda_uart_console_init(void)
+{
+	register_console(&rda_uart_console);
+
+	return 0;
+}
+console_initcall(rda_uart_console_init);
+
+static void rda_uart_early_console_write(struct console *co,
+					 const char *s,
+					 u_int count)
+{
+	struct earlycon_device *dev = co->data;
+
+	rda_uart_port_write(&dev->port, s, count);
+}
+
+static int __init
+rda_uart_early_console_setup(struct earlycon_device *device, const char *opt)
+{
+	if (!device->port.membase)
+		return -ENODEV;
+
+	device->con->write = rda_uart_early_console_write;
+
+	return 0;
+}
+
+OF_EARLYCON_DECLARE(rda, "rda,8810pl-uart",
+		    rda_uart_early_console_setup);
+
+#define RDA_UART_CONSOLE (&rda_uart_console)
+#else
+#define RDA_UART_CONSOLE NULL
+#endif /* CONFIG_SERIAL_RDA_CONSOLE */
+
+static struct uart_driver rda_uart_driver = {
+	.owner = THIS_MODULE,
+	.driver_name = "rda-uart",
+	.dev_name = RDA_UART_DEV_NAME,
+	.nr = RDA_UART_PORT_NUM,
+	.cons = RDA_UART_CONSOLE,
+};
+
+static const struct of_device_id rda_uart_dt_matches[] = {
+	{ .compatible = "rda,8810pl-uart" },
+	{ }
+};
+MODULE_DEVICE_TABLE(of, rda_uart_dt_matches);
+
+static int rda_uart_probe(struct platform_device *pdev)
+{
+	struct resource *res_mem;
+	struct rda_uart_port *rda_port;
+	int ret, irq;
+
+	if (pdev->dev.of_node)
+		pdev->id = of_alias_get_id(pdev->dev.of_node, "serial");
+
+	if (pdev->id < 0 || pdev->id >= RDA_UART_PORT_NUM) {
+		dev_err(&pdev->dev, "id %d out of range\n", pdev->id);
+		return -EINVAL;
+	}
+
+	res_mem = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	if (!res_mem) {
+		dev_err(&pdev->dev, "could not get mem\n");
+		return -ENODEV;
+	}
+
+	irq = platform_get_irq(pdev, 0);
+	if (irq < 0) {
+		dev_err(&pdev->dev, "could not get irq\n");
+		return irq;
+	}
+
+	if (rda_uart_ports[pdev->id]) {
+		dev_err(&pdev->dev, "port %d already allocated\n", pdev->id);
+		return -EBUSY;
+	}
+
+	rda_port = devm_kzalloc(&pdev->dev, sizeof(*rda_port), GFP_KERNEL);
+	if (!rda_port)
+		return -ENOMEM;
+
+	rda_port->clk = devm_clk_get(&pdev->dev, NULL);
+	if (IS_ERR(rda_port->clk)) {
+		dev_err(&pdev->dev, "could not get clk\n");
+		return PTR_ERR(rda_port->clk);
+	}
+
+	rda_port->port.dev = &pdev->dev;
+	rda_port->port.regshift = 0;
+	rda_port->port.line = pdev->id;
+	rda_port->port.type = PORT_RDA;
+	rda_port->port.iotype = UPIO_MEM;
+	rda_port->port.mapbase = res_mem->start;
+	rda_port->port.irq = irq;
+	rda_port->port.uartclk = clk_get_rate(rda_port->clk);
+	if (rda_port->port.uartclk == 0) {
+		dev_err(&pdev->dev, "clock rate is zero\n");
+		return -EINVAL;
+	}
+	rda_port->port.flags = UPF_BOOT_AUTOCONF | UPF_IOREMAP |
+			       UPF_LOW_LATENCY;
+	rda_port->port.x_char = 0;
+	rda_port->port.fifosize = RDA_UART_TX_FIFO_SIZE;
+	rda_port->port.ops = &rda_uart_ops;
+
+	rda_uart_ports[pdev->id] = rda_port;
+	platform_set_drvdata(pdev, rda_port);
+
+	ret = uart_add_one_port(&rda_uart_driver, &rda_port->port);
+	if (ret)
+		rda_uart_ports[pdev->id] = NULL;
+
+	return ret;
+}
+
+static int rda_uart_remove(struct platform_device *pdev)
+{
+	struct rda_uart_port *rda_port = platform_get_drvdata(pdev);
+
+	uart_remove_one_port(&rda_uart_driver, &rda_port->port);
+	rda_uart_ports[pdev->id] = NULL;
+
+	return 0;
+}
+
+static struct platform_driver rda_uart_platform_driver = {
+	.probe = rda_uart_probe,
+	.remove = rda_uart_remove,
+	.driver = {
+		.name = "rda-uart",
+		.of_match_table = rda_uart_dt_matches,
+	},
+};
+
+static int __init rda_uart_init(void)
+{
+	int ret;
+
+	ret = uart_register_driver(&rda_uart_driver);
+	if (ret)
+		return ret;
+
+	ret = platform_driver_register(&rda_uart_platform_driver);
+	if (ret)
+		uart_unregister_driver(&rda_uart_driver);
+
+	return ret;
+}
+
+static void __init rda_uart_exit(void)
+{
+	platform_driver_unregister(&rda_uart_platform_driver);
+	uart_unregister_driver(&rda_uart_driver);
+}
+
+module_init(rda_uart_init);
+module_exit(rda_uart_exit);
+
+MODULE_AUTHOR("Manivannan Sadhasivam <manivannan.sadhasivam@linaro.org>");
+MODULE_DESCRIPTION("RDA8810PL serial device driver");
+MODULE_LICENSE("GPL");