tty/serial: add support for Xilinx PS UART

The Xilinx PS Uart is used on the new ARM based SoC. This
UART is not compatible with others such that a seperate
driver is required.

Signed-off-by: John Linn <john.linn@xilinx.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

1 files changed, 1113 insertions, 0 deletions

diff --git a/drivers/tty/serial/xilinx_uartps.c b/drivers/tty/serial/xilinx_uartps.c
new file mode 100644
index 000000000000..19cc1e8149dd
--- /dev/null
+++ b/drivers/tty/serial/xilinx_uartps.c
@@ -0,0 +1,1113 @@
+/*
+ * Xilinx PS UART driver
+ *
+ * 2011 (c) Xilinx Inc.
+ *
+ * This program is free software; you can redistribute it
+ * and/or modify it under the terms of the GNU General Public
+ * License as published by the Free Software Foundation;
+ * either version 2 of the License, or (at your option) any
+ * later version.
+ *
+ */
+
+#include <linux/platform_device.h>
+#include <linux/serial_core.h>
+#include <linux/console.h>
+#include <linux/serial.h>
+#include <linux/irq.h>
+#include <linux/io.h>
+#include <linux/of.h>
+
+#define XUARTPS_TTY_NAME	"ttyPS"
+#define XUARTPS_NAME		"xuartps"
+#define XUARTPS_MAJOR		0	/* use dynamic node allocation */
+#define XUARTPS_MINOR		0	/* works best with devtmpfs */
+#define XUARTPS_NR_PORTS	2
+#define XUARTPS_FIFO_SIZE	16	/* FIFO size */
+#define XUARTPS_REGISTER_SPACE	0xFFF
+
+#define xuartps_readl(offset)		ioread32(port->membase + offset)
+#define xuartps_writel(val, offset)	iowrite32(val, port->membase + offset)
+
+/********************************Register Map********************************/
+/** UART
+ *
+ * Register offsets for the UART.
+ *
+ */
+#define XUARTPS_CR_OFFSET	0x00  /* Control Register [8:0] */
+#define XUARTPS_MR_OFFSET	0x04  /* Mode Register [10:0] */
+#define XUARTPS_IER_OFFSET	0x08  /* Interrupt Enable [10:0] */
+#define XUARTPS_IDR_OFFSET	0x0C  /* Interrupt Disable [10:0] */
+#define XUARTPS_IMR_OFFSET	0x10  /* Interrupt Mask [10:0] */
+#define XUARTPS_ISR_OFFSET	0x14  /* Interrupt Status [10:0]*/
+#define XUARTPS_BAUDGEN_OFFSET	0x18  /* Baud Rate Generator [15:0] */
+#define XUARTPS_RXTOUT_OFFSET	0x1C  /* RX Timeout [7:0] */
+#define XUARTPS_RXWM_OFFSET	0x20  /* RX FIFO Trigger Level [5:0] */
+#define XUARTPS_MODEMCR_OFFSET	0x24  /* Modem Control [5:0] */
+#define XUARTPS_MODEMSR_OFFSET	0x28  /* Modem Status [8:0] */
+#define XUARTPS_SR_OFFSET	0x2C  /* Channel Status [11:0] */
+#define XUARTPS_FIFO_OFFSET	0x30  /* FIFO [15:0] or [7:0] */
+#define XUARTPS_BAUDDIV_OFFSET	0x34  /* Baud Rate Divider [7:0] */
+#define XUARTPS_FLOWDEL_OFFSET	0x38  /* Flow Delay [15:0] */
+#define XUARTPS_IRRX_PWIDTH_OFFSET 0x3C /* IR Minimum Received Pulse
+						Width [15:0] */
+#define XUARTPS_IRTX_PWIDTH_OFFSET 0x40 /* IR Transmitted pulse
+						Width [7:0] */
+#define XUARTPS_TXWM_OFFSET	0x44  /* TX FIFO Trigger Level [5:0] */
+
+/** Control Register
+ *
+ * The Control register (CR) controls the major functions of the device.
+ *
+ * Control Register Bit Definitions
+ */
+#define XUARTPS_CR_STOPBRK	0x00000100  /* Stop TX break */
+#define XUARTPS_CR_STARTBRK	0x00000080  /* Set TX break */
+#define XUARTPS_CR_TX_DIS	0x00000020  /* TX disabled. */
+#define XUARTPS_CR_TX_EN	0x00000010  /* TX enabled */
+#define XUARTPS_CR_RX_DIS	0x00000008  /* RX disabled. */
+#define XUARTPS_CR_RX_EN	0x00000004  /* RX enabled */
+#define XUARTPS_CR_TXRST	0x00000002  /* TX logic reset */
+#define XUARTPS_CR_RXRST	0x00000001  /* RX logic reset */
+#define XUARTPS_CR_RST_TO	0x00000040  /* Restart Timeout Counter */
+
+/** Mode Register
+ *
+ * The mode register (MR) defines the mode of transfer as well as the data
+ * format. If this register is modified during transmission or reception,
+ * data validity cannot be guaranteed.
+ *
+ * Mode Register Bit Definitions
+ *
+ */
+#define XUARTPS_MR_CLKSEL		0x00000001  /* Pre-scalar selection */
+#define XUARTPS_MR_CHMODE_L_LOOP	0x00000200  /* Local loop back mode */
+#define XUARTPS_MR_CHMODE_NORM		0x00000000  /* Normal mode */
+
+#define XUARTPS_MR_STOPMODE_2_BIT	0x00000080  /* 2 stop bits */
+#define XUARTPS_MR_STOPMODE_1_BIT	0x00000000  /* 1 stop bit */
+
+#define XUARTPS_MR_PARITY_NONE		0x00000020  /* No parity mode */
+#define XUARTPS_MR_PARITY_MARK		0x00000018  /* Mark parity mode */
+#define XUARTPS_MR_PARITY_SPACE		0x00000010  /* Space parity mode */
+#define XUARTPS_MR_PARITY_ODD		0x00000008  /* Odd parity mode */
+#define XUARTPS_MR_PARITY_EVEN		0x00000000  /* Even parity mode */
+
+#define XUARTPS_MR_CHARLEN_6_BIT	0x00000006  /* 6 bits data */
+#define XUARTPS_MR_CHARLEN_7_BIT	0x00000004  /* 7 bits data */
+#define XUARTPS_MR_CHARLEN_8_BIT	0x00000000  /* 8 bits data */
+
+/** Interrupt Registers
+ *
+ * Interrupt control logic uses the interrupt enable register (IER) and the
+ * interrupt disable register (IDR) to set the value of the bits in the
+ * interrupt mask register (IMR). The IMR determines whether to pass an
+ * interrupt to the interrupt status register (ISR).
+ * Writing a 1 to IER Enables an interrupt, writing a 1 to IDR disables an
+ * interrupt. IMR and ISR are read only, and IER and IDR are write only.
+ * Reading either IER or IDR returns 0x00.
+ *
+ * All four registers have the same bit definitions.
+ */
+#define XUARTPS_IXR_TOUT	0x00000100 /* RX Timeout error interrupt */
+#define XUARTPS_IXR_PARITY	0x00000080 /* Parity error interrupt */
+#define XUARTPS_IXR_FRAMING	0x00000040 /* Framing error interrupt */
+#define XUARTPS_IXR_OVERRUN	0x00000020 /* Overrun error interrupt */
+#define XUARTPS_IXR_TXFULL	0x00000010 /* TX FIFO Full interrupt */
+#define XUARTPS_IXR_TXEMPTY	0x00000008 /* TX FIFO empty interrupt */
+#define XUARTPS_ISR_RXEMPTY	0x00000002 /* RX FIFO empty interrupt */
+#define XUARTPS_IXR_RXTRIG	0x00000001 /* RX FIFO trigger interrupt */
+#define XUARTPS_IXR_RXFULL	0x00000004 /* RX FIFO full interrupt. */
+#define XUARTPS_IXR_RXEMPTY	0x00000002 /* RX FIFO empty interrupt. */
+#define XUARTPS_IXR_MASK	0x00001FFF /* Valid bit mask */
+
+/** Channel Status Register
+ *
+ * The channel status register (CSR) is provided to enable the control logic
+ * to monitor the status of bits in the channel interrupt status register,
+ * even if these are masked out by the interrupt mask register.
+ */
+#define XUARTPS_SR_RXEMPTY	0x00000002 /* RX FIFO empty */
+#define XUARTPS_SR_TXEMPTY	0x00000008 /* TX FIFO empty */
+#define XUARTPS_SR_TXFULL	0x00000010 /* TX FIFO full */
+#define XUARTPS_SR_RXTRIG	0x00000001 /* Rx Trigger */
+
+/**
+ * xuartps_isr - Interrupt handler
+ * @irq: Irq number
+ * @dev_id: Id of the port
+ *
+ * Returns IRQHANDLED
+ **/
+static irqreturn_t xuartps_isr(int irq, void *dev_id)
+{
+	struct uart_port *port = (struct uart_port *)dev_id;
+	struct tty_struct *tty;
+	unsigned long flags;
+	unsigned int isrstatus, numbytes;
+	unsigned int data;
+	char status = TTY_NORMAL;
+
+	/* Get the tty which could be NULL so don't assume it's valid */
+	tty = tty_port_tty_get(&port->state->port);
+
+	spin_lock_irqsave(&port->lock, flags);
+
+	/* Read the interrupt status register to determine which
+	 * interrupt(s) is/are active.
+	 */
+	isrstatus = xuartps_readl(XUARTPS_ISR_OFFSET);
+
+	/* drop byte with parity error if IGNPAR specified */
+	if (isrstatus & port->ignore_status_mask & XUARTPS_IXR_PARITY)
+		isrstatus &= ~(XUARTPS_IXR_RXTRIG | XUARTPS_IXR_TOUT);
+
+	isrstatus &= port->read_status_mask;
+	isrstatus &= ~port->ignore_status_mask;
+
+	if ((isrstatus & XUARTPS_IXR_TOUT) ||
+		(isrstatus & XUARTPS_IXR_RXTRIG)) {
+		/* Receive Timeout Interrupt */
+		while ((xuartps_readl(XUARTPS_SR_OFFSET) &
+			XUARTPS_SR_RXEMPTY) != XUARTPS_SR_RXEMPTY) {
+			data = xuartps_readl(XUARTPS_FIFO_OFFSET);
+			port->icount.rx++;
+
+			if (isrstatus & XUARTPS_IXR_PARITY) {
+				port->icount.parity++;
+				status = TTY_PARITY;
+			} else if (isrstatus & XUARTPS_IXR_FRAMING) {
+				port->icount.frame++;
+				status = TTY_FRAME;
+			} else if (isrstatus & XUARTPS_IXR_OVERRUN)
+				port->icount.overrun++;
+
+			if (tty)
+				uart_insert_char(port, isrstatus,
+						XUARTPS_IXR_OVERRUN, data,
+						status);
+		}
+		spin_unlock(&port->lock);
+		if (tty)
+			tty_flip_buffer_push(tty);
+		spin_lock(&port->lock);
+	}
+
+	/* Dispatch an appropriate handler */
+	if ((isrstatus & XUARTPS_IXR_TXEMPTY) == XUARTPS_IXR_TXEMPTY) {
+		if (uart_circ_empty(&port->state->xmit)) {
+			xuartps_writel(XUARTPS_IXR_TXEMPTY,
+						XUARTPS_IDR_OFFSET);
+		} else {
+			numbytes = port->fifosize;
+			/* Break if no more data available in the UART buffer */
+			while (numbytes--) {
+				if (uart_circ_empty(&port->state->xmit))
+					break;
+				/* Get the data from the UART circular buffer
+				 * and write it to the xuartps's TX_FIFO
+				 * register.
+				 */
+				xuartps_writel(
+					port->state->xmit.buf[port->state->xmit.
+					tail], XUARTPS_FIFO_OFFSET);
+
+				port->icount.tx++;
+
+				/* Adjust the tail of the UART buffer and wrap
+				 * the buffer if it reaches limit.
+				 */
+				port->state->xmit.tail =
+					(port->state->xmit.tail + 1) & \
+						(UART_XMIT_SIZE - 1);
+			}
+
+			if (uart_circ_chars_pending(
+					&port->state->xmit) < WAKEUP_CHARS)
+				uart_write_wakeup(port);
+		}
+	}
+
+	xuartps_writel(isrstatus, XUARTPS_ISR_OFFSET);
+
+	/* be sure to release the lock and tty before leaving */
+	spin_unlock_irqrestore(&port->lock, flags);
+	tty_kref_put(tty);
+
+	return IRQ_HANDLED;
+}
+
+/**
+ * xuartps_set_baud_rate - Calculate and set the baud rate
+ * @port: Handle to the uart port structure
+ * @baud: Baud rate to set
+ *
+ * Returns baud rate, requested baud when possible, or actual baud when there
+ *	was too much error
+ **/
+static unsigned int xuartps_set_baud_rate(struct uart_port *port,
+						unsigned int baud)
+{
+	unsigned int sel_clk;
+	unsigned int calc_baud = 0;
+	unsigned int brgr_val, brdiv_val;
+	unsigned int bauderror;
+
+	/* Formula to obtain baud rate is
+	 *	baud_tx/rx rate = sel_clk/CD * (BDIV + 1)
+	 *	input_clk = (Uart User Defined Clock or Apb Clock)
+	 *		depends on UCLKEN in MR Reg
+	 *	sel_clk = input_clk or input_clk/8;
+	 *		depends on CLKS in MR reg
+	 *	CD and BDIV depends on values in
+	 *			baud rate generate register
+	 *			baud rate clock divisor register
+	 */
+	sel_clk = port->uartclk;
+	if (xuartps_readl(XUARTPS_MR_OFFSET) & XUARTPS_MR_CLKSEL)
+		sel_clk = sel_clk / 8;
+
+	/* Find the best values for baud generation */
+	for (brdiv_val = 4; brdiv_val < 255; brdiv_val++) {
+
+		brgr_val = sel_clk / (baud * (brdiv_val + 1));
+		if (brgr_val < 2 || brgr_val > 65535)
+			continue;
+
+		calc_baud = sel_clk / (brgr_val * (brdiv_val + 1));
+
+		if (baud > calc_baud)
+			bauderror = baud - calc_baud;
+		else
+			bauderror = calc_baud - baud;
+
+		/* use the values when percent error is acceptable */
+		if (((bauderror * 100) / baud) < 3) {
+			calc_baud = baud;
+			break;
+		}
+	}
+
+	/* Set the values for the new baud rate */
+	xuartps_writel(brgr_val, XUARTPS_BAUDGEN_OFFSET);
+	xuartps_writel(brdiv_val, XUARTPS_BAUDDIV_OFFSET);
+
+	return calc_baud;
+}
+
+/*----------------------Uart Operations---------------------------*/
+
+/**
+ * xuartps_start_tx -  Start transmitting bytes
+ * @port: Handle to the uart port structure
+ *
+ **/
+static void xuartps_start_tx(struct uart_port *port)
+{
+	unsigned int status, numbytes = port->fifosize;
+
+	if (uart_circ_empty(&port->state->xmit) || uart_tx_stopped(port))
+		return;
+
+	status = xuartps_readl(XUARTPS_CR_OFFSET);
+	/* Set the TX enable bit and clear the TX disable bit to enable the
+	 * transmitter.
+	 */
+	xuartps_writel((status & ~XUARTPS_CR_TX_DIS) | XUARTPS_CR_TX_EN,
+		XUARTPS_CR_OFFSET);
+
+	while (numbytes-- && ((xuartps_readl(XUARTPS_SR_OFFSET)
+		& XUARTPS_SR_TXFULL)) != XUARTPS_SR_TXFULL) {
+
+		/* Break if no more data available in the UART buffer */
+		if (uart_circ_empty(&port->state->xmit))
+			break;
+
+		/* Get the data from the UART circular buffer and
+		 * write it to the xuartps's TX_FIFO register.
+		 */
+		xuartps_writel(
+			port->state->xmit.buf[port->state->xmit.tail],
+			XUARTPS_FIFO_OFFSET);
+		port->icount.tx++;
+
+		/* Adjust the tail of the UART buffer and wrap
+		 * the buffer if it reaches limit.
+		 */
+		port->state->xmit.tail = (port->state->xmit.tail + 1) &
+					(UART_XMIT_SIZE - 1);
+	}
+
+	/* Enable the TX Empty interrupt */
+	xuartps_writel(XUARTPS_IXR_TXEMPTY, XUARTPS_IER_OFFSET);
+
+	if (uart_circ_chars_pending(&port->state->xmit) < WAKEUP_CHARS)
+		uart_write_wakeup(port);
+}
+
+/**
+ * xuartps_stop_tx - Stop TX
+ * @port: Handle to the uart port structure
+ *
+ **/
+static void xuartps_stop_tx(struct uart_port *port)
+{
+	unsigned int regval;
+
+	regval = xuartps_readl(XUARTPS_CR_OFFSET);
+	regval |= XUARTPS_CR_TX_DIS;
+	/* Disable the transmitter */
+	xuartps_writel(regval, XUARTPS_CR_OFFSET);
+}
+
+/**
+ * xuartps_stop_rx - Stop RX
+ * @port: Handle to the uart port structure
+ *
+ **/
+static void xuartps_stop_rx(struct uart_port *port)
+{
+	unsigned int regval;
+
+	regval = xuartps_readl(XUARTPS_CR_OFFSET);
+	regval |= XUARTPS_CR_RX_DIS;
+	/* Disable the receiver */
+	xuartps_writel(regval, XUARTPS_CR_OFFSET);
+}
+
+/**
+ * xuartps_tx_empty -  Check whether TX is empty
+ * @port: Handle to the uart port structure
+ *
+ * Returns TIOCSER_TEMT on success, 0 otherwise
+ **/
+static unsigned int xuartps_tx_empty(struct uart_port *port)
+{
+	unsigned int status;
+
+	status = xuartps_readl(XUARTPS_ISR_OFFSET) & XUARTPS_IXR_TXEMPTY;
+	return status ? TIOCSER_TEMT : 0;
+}
+
+/**
+ * xuartps_break_ctl - Based on the input ctl we have to start or stop
+ *			transmitting char breaks
+ * @port: Handle to the uart port structure
+ * @ctl: Value based on which start or stop decision is taken
+ *
+ **/
+static void xuartps_break_ctl(struct uart_port *port, int ctl)
+{
+	unsigned int status;
+	unsigned long flags;
+
+	spin_lock_irqsave(&port->lock, flags);
+
+	status = xuartps_readl(XUARTPS_CR_OFFSET);
+
+	if (ctl == -1)
+		xuartps_writel(XUARTPS_CR_STARTBRK | status,
+					XUARTPS_CR_OFFSET);
+	else {
+		if ((status & XUARTPS_CR_STOPBRK) == 0)
+			xuartps_writel(XUARTPS_CR_STOPBRK | status,
+					 XUARTPS_CR_OFFSET);
+	}
+	spin_unlock_irqrestore(&port->lock, flags);
+}
+
+/**
+ * xuartps_set_termios - termios operations, handling data length, parity,
+ *				stop bits, flow control, baud rate
+ * @port: Handle to the uart port structure
+ * @termios: Handle to the input termios structure
+ * @old: Values of the previously saved termios structure
+ *
+ **/
+static void xuartps_set_termios(struct uart_port *port,
+				struct ktermios *termios, struct ktermios *old)
+{
+	unsigned int cval = 0;
+	unsigned int baud;
+	unsigned long flags;
+	unsigned int ctrl_reg, mode_reg;
+
+	spin_lock_irqsave(&port->lock, flags);
+
+	/* Empty the receive FIFO 1st before making changes */
+	while ((xuartps_readl(XUARTPS_SR_OFFSET) &
+		 XUARTPS_SR_RXEMPTY) != XUARTPS_SR_RXEMPTY) {
+		xuartps_readl(XUARTPS_FIFO_OFFSET);
+	}
+
+	/* Disable the TX and RX to set baud rate */
+	xuartps_writel(xuartps_readl(XUARTPS_CR_OFFSET) |
+			(XUARTPS_CR_TX_DIS | XUARTPS_CR_RX_DIS),
+			XUARTPS_CR_OFFSET);
+
+	/* Min baud rate = 6bps and Max Baud Rate is 10Mbps for 100Mhz clk */
+	baud = uart_get_baud_rate(port, termios, old, 0, 10000000);
+	baud = xuartps_set_baud_rate(port, baud);
+	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);
+
+	/* Set TX/RX Reset */
+	xuartps_writel(xuartps_readl(XUARTPS_CR_OFFSET) |
+			(XUARTPS_CR_TXRST | XUARTPS_CR_RXRST),
+			XUARTPS_CR_OFFSET);
+
+	ctrl_reg = xuartps_readl(XUARTPS_CR_OFFSET);
+
+	/* Clear the RX disable and TX disable bits and then set the TX enable
+	 * bit and RX enable bit to enable the transmitter and receiver.
+	 */
+	xuartps_writel(
+		(ctrl_reg & ~(XUARTPS_CR_TX_DIS | XUARTPS_CR_RX_DIS))
+			| (XUARTPS_CR_TX_EN | XUARTPS_CR_RX_EN),
+			XUARTPS_CR_OFFSET);
+
+	xuartps_writel(10, XUARTPS_RXTOUT_OFFSET);
+
+	port->read_status_mask = XUARTPS_IXR_TXEMPTY | XUARTPS_IXR_RXTRIG |
+			XUARTPS_IXR_OVERRUN | XUARTPS_IXR_TOUT;
+	port->ignore_status_mask = 0;
+
+	if (termios->c_iflag & INPCK)
+		port->read_status_mask |= XUARTPS_IXR_PARITY |
+		XUARTPS_IXR_FRAMING;
+
+	if (termios->c_iflag & IGNPAR)
+		port->ignore_status_mask |= XUARTPS_IXR_PARITY |
+			XUARTPS_IXR_FRAMING | XUARTPS_IXR_OVERRUN;
+
+	/* ignore all characters if CREAD is not set */
+	if ((termios->c_cflag & CREAD) == 0)
+		port->ignore_status_mask |= XUARTPS_IXR_RXTRIG |
+			XUARTPS_IXR_TOUT | XUARTPS_IXR_PARITY |
+			XUARTPS_IXR_FRAMING | XUARTPS_IXR_OVERRUN;
+
+	mode_reg = xuartps_readl(XUARTPS_MR_OFFSET);
+
+	/* Handling Data Size */
+	switch (termios->c_cflag & CSIZE) {
+	case CS6:
+		cval |= XUARTPS_MR_CHARLEN_6_BIT;
+		break;
+	case CS7:
+		cval |= XUARTPS_MR_CHARLEN_7_BIT;
+		break;
+	default:
+	case CS8:
+		cval |= XUARTPS_MR_CHARLEN_8_BIT;
+		termios->c_cflag &= ~CSIZE;
+		termios->c_cflag |= CS8;
+		break;
+	}
+
+	/* Handling Parity and Stop Bits length */
+	if (termios->c_cflag & CSTOPB)
+		cval |= XUARTPS_MR_STOPMODE_2_BIT; /* 2 STOP bits */
+	else
+		cval |= XUARTPS_MR_STOPMODE_1_BIT; /* 1 STOP bit */
+
+	if (termios->c_cflag & PARENB) {
+		/* Mark or Space parity */
+		if (termios->c_cflag & CMSPAR) {
+			if (termios->c_cflag & PARODD)
+				cval |= XUARTPS_MR_PARITY_MARK;
+			else
+				cval |= XUARTPS_MR_PARITY_SPACE;
+		} else if (termios->c_cflag & PARODD)
+				cval |= XUARTPS_MR_PARITY_ODD;
+			else
+				cval |= XUARTPS_MR_PARITY_EVEN;
+	} else
+		cval |= XUARTPS_MR_PARITY_NONE;
+	xuartps_writel(cval , XUARTPS_MR_OFFSET);
+
+	spin_unlock_irqrestore(&port->lock, flags);
+}
+
+/**
+ * xuartps_startup - Called when an application opens a xuartps port
+ * @port: Handle to the uart port structure
+ *
+ * Returns 0 on success, negative error otherwise
+ **/
+static int xuartps_startup(struct uart_port *port)
+{
+	unsigned int retval = 0, status = 0;
+
+	retval = request_irq(port->irq, xuartps_isr, 0, XUARTPS_NAME,
+								(void *)port);
+	if (retval)
+		return retval;
+
+	/* Disable the TX and RX */
+	xuartps_writel(XUARTPS_CR_TX_DIS | XUARTPS_CR_RX_DIS,
+						XUARTPS_CR_OFFSET);
+
+	/* Set the Control Register with TX/RX Enable, TX/RX Reset,
+	 * no break chars.
+	 */
+	xuartps_writel(XUARTPS_CR_TXRST | XUARTPS_CR_RXRST,
+				XUARTPS_CR_OFFSET);
+
+	status = xuartps_readl(XUARTPS_CR_OFFSET);
+
+	/* Clear the RX disable and TX disable bits and then set the TX enable
+	 * bit and RX enable bit to enable the transmitter and receiver.
+	 */
+	xuartps_writel((status & ~(XUARTPS_CR_TX_DIS | XUARTPS_CR_RX_DIS))
+			| (XUARTPS_CR_TX_EN | XUARTPS_CR_RX_EN |
+			XUARTPS_CR_STOPBRK), XUARTPS_CR_OFFSET);
+
+	/* Set the Mode Register with normal mode,8 data bits,1 stop bit,
+	 * no parity.
+	 */
+	xuartps_writel(XUARTPS_MR_CHMODE_NORM | XUARTPS_MR_STOPMODE_1_BIT
+		| XUARTPS_MR_PARITY_NONE | XUARTPS_MR_CHARLEN_8_BIT,
+		 XUARTPS_MR_OFFSET);
+
+	/* Set the RX FIFO Trigger level to 14 assuming FIFO size as 16 */
+	xuartps_writel(14, XUARTPS_RXWM_OFFSET);
+
+	/* Receive Timeout register is enabled with value of 10 */
+	xuartps_writel(10, XUARTPS_RXTOUT_OFFSET);
+
+
+	/* Set the Interrupt Registers with desired interrupts */
+	xuartps_writel(XUARTPS_IXR_TXEMPTY | XUARTPS_IXR_PARITY |
+		XUARTPS_IXR_FRAMING | XUARTPS_IXR_OVERRUN |
+		XUARTPS_IXR_RXTRIG | XUARTPS_IXR_TOUT, XUARTPS_IER_OFFSET);
+	xuartps_writel(~(XUARTPS_IXR_TXEMPTY | XUARTPS_IXR_PARITY |
+		XUARTPS_IXR_FRAMING | XUARTPS_IXR_OVERRUN |
+		XUARTPS_IXR_RXTRIG | XUARTPS_IXR_TOUT), XUARTPS_IDR_OFFSET);
+
+	return retval;
+}
+
+/**
+ * xuartps_shutdown - Called when an application closes a xuartps port
+ * @port: Handle to the uart port structure
+ *
+ **/
+static void xuartps_shutdown(struct uart_port *port)
+{
+	int status;
+
+	/* Disable interrupts */
+	status = xuartps_readl(XUARTPS_IMR_OFFSET);
+	xuartps_writel(status, XUARTPS_IDR_OFFSET);
+
+	/* Disable the TX and RX */
+	xuartps_writel(XUARTPS_CR_TX_DIS | XUARTPS_CR_RX_DIS,
+				 XUARTPS_CR_OFFSET);
+	free_irq(port->irq, port);
+}
+
+/**
+ * xuartps_type - Set UART type to xuartps port
+ * @port: Handle to the uart port structure
+ *
+ * Returns string on success, NULL otherwise
+ **/
+static const char *xuartps_type(struct uart_port *port)
+{
+	return port->type == PORT_XUARTPS ? XUARTPS_NAME : NULL;
+}
+
+/**
+ * xuartps_verify_port - Verify the port params
+ * @port: Handle to the uart port structure
+ * @ser: Handle to the structure whose members are compared
+ *
+ * Returns 0 if success otherwise -EINVAL
+ **/
+static int xuartps_verify_port(struct uart_port *port,
+					struct serial_struct *ser)
+{
+	if (ser->type != PORT_UNKNOWN && ser->type != PORT_XUARTPS)
+		return -EINVAL;
+	if (port->irq != ser->irq)
+		return -EINVAL;
+	if (ser->io_type != UPIO_MEM)
+		return -EINVAL;
+	if (port->iobase != ser->port)
+		return -EINVAL;
+	if (ser->hub6 != 0)
+		return -EINVAL;
+	return 0;
+}
+
+/**
+ * xuartps_request_port - Claim the memory region attached to xuartps port,
+ *				called when the driver adds a xuartps port via
+ *				uart_add_one_port()
+ * @port: Handle to the uart port structure
+ *
+ * Returns 0, -ENOMEM if request fails
+ **/
+static int xuartps_request_port(struct uart_port *port)
+{
+	if (!request_mem_region(port->mapbase, XUARTPS_REGISTER_SPACE,
+					 XUARTPS_NAME)) {
+		return -ENOMEM;
+	}
+
+	port->membase = ioremap(port->mapbase, XUARTPS_REGISTER_SPACE);
+	if (!port->membase) {
+		dev_err(port->dev, "Unable to map registers\n");
+		release_mem_region(port->mapbase, XUARTPS_REGISTER_SPACE);
+		return -ENOMEM;
+	}
+	return 0;
+}
+
+/**
+ * xuartps_release_port - Release the memory region attached to a xuartps
+ *				port, called when the driver removes a xuartps
+ *				port via uart_remove_one_port().
+ * @port: Handle to the uart port structure
+ *
+ **/
+static void xuartps_release_port(struct uart_port *port)
+{
+	release_mem_region(port->mapbase, XUARTPS_REGISTER_SPACE);
+	iounmap(port->membase);
+	port->membase = NULL;
+}
+
+/**
+ * xuartps_config_port - Configure xuartps, called when the driver adds a
+ *				xuartps port
+ * @port: Handle to the uart port structure
+ * @flags: If any
+ *
+ **/
+static void xuartps_config_port(struct uart_port *port, int flags)
+{
+	if (flags & UART_CONFIG_TYPE && xuartps_request_port(port) == 0)
+		port->type = PORT_XUARTPS;
+}
+
+/**
+ * xuartps_get_mctrl - Get the modem control state
+ *
+ * @port: Handle to the uart port structure
+ *
+ * Returns the modem control state
+ *
+ **/
+static unsigned int xuartps_get_mctrl(struct uart_port *port)
+{
+	return TIOCM_CTS | TIOCM_DSR | TIOCM_CAR;
+}
+
+static void xuartps_set_mctrl(struct uart_port *port, unsigned int mctrl)
+{
+	/* N/A */
+}
+
+static void xuartps_enable_ms(struct uart_port *port)
+{
+	/* N/A */
+}
+
+/** The UART operations structure
+ */
+static struct uart_ops xuartps_ops = {
+	.set_mctrl	= xuartps_set_mctrl,
+	.get_mctrl	= xuartps_get_mctrl,
+	.enable_ms	= xuartps_enable_ms,
+
+	.start_tx	= xuartps_start_tx,	/* Start transmitting */
+	.stop_tx	= xuartps_stop_tx,	/* Stop transmission */
+	.stop_rx	= xuartps_stop_rx,	/* Stop reception */
+	.tx_empty	= xuartps_tx_empty,	/* Transmitter busy? */
+	.break_ctl	= xuartps_break_ctl,	/* Start/stop
+						 * transmitting break
+						 */
+	.set_termios	= xuartps_set_termios,	/* Set termios */
+	.startup	= xuartps_startup,	/* App opens xuartps */
+	.shutdown	= xuartps_shutdown,	/* App closes xuartps */
+	.type		= xuartps_type,		/* Set UART type */
+	.verify_port	= xuartps_verify_port,	/* Verification of port
+						 * params
+						 */
+	.request_port	= xuartps_request_port,	/* Claim resources
+						 * associated with a
+						 * xuartps port
+						 */
+	.release_port	= xuartps_release_port,	/* Release resources
+						 * associated with a
+						 * xuartps port
+						 */
+	.config_port	= xuartps_config_port,	/* Configure when driver
+						 * adds a xuartps port
+						 */
+};
+
+static struct uart_port xuartps_port[2];
+
+/**
+ * xuartps_get_port - Configure the port from the platform device resource
+ *			info
+ *
+ * Returns a pointer to a uart_port or NULL for failure
+ **/
+static struct uart_port *xuartps_get_port(void)
+{
+	struct uart_port *port;
+	int id;
+
+	/* Find the next unused port */
+	for (id = 0; id < XUARTPS_NR_PORTS; id++)
+		if (xuartps_port[id].mapbase == 0)
+			break;
+
+	if (id >= XUARTPS_NR_PORTS)
+		return NULL;
+
+	port = &xuartps_port[id];
+
+	/* At this point, we've got an empty uart_port struct, initialize it */
+	spin_lock_init(&port->lock);
+	port->membase	= NULL;
+	port->iobase	= 1; /* mark port in use */
+	port->irq	= 0;
+	port->type	= PORT_UNKNOWN;
+	port->iotype	= UPIO_MEM32;
+	port->flags	= UPF_BOOT_AUTOCONF;
+	port->ops	= &xuartps_ops;
+	port->fifosize	= XUARTPS_FIFO_SIZE;
+	port->line	= id;
+	port->dev	= NULL;
+	return port;
+}
+
+/*-----------------------Console driver operations--------------------------*/
+
+#ifdef CONFIG_SERIAL_XILINX_PS_UART_CONSOLE
+/**
+ * xuartps_console_wait_tx - Wait for the TX to be full
+ * @port: Handle to the uart port structure
+ *
+ **/
+static void xuartps_console_wait_tx(struct uart_port *port)
+{
+	while ((xuartps_readl(XUARTPS_SR_OFFSET) & XUARTPS_SR_TXEMPTY)
+				!= XUARTPS_SR_TXEMPTY)
+		barrier();
+}
+
+/**
+ * xuartps_console_putchar - write the character to the FIFO buffer
+ * @port: Handle to the uart port structure
+ * @ch: Character to be written
+ *
+ **/
+static void xuartps_console_putchar(struct uart_port *port, int ch)
+{
+	xuartps_console_wait_tx(port);
+	xuartps_writel(ch, XUARTPS_FIFO_OFFSET);
+}
+
+/**
+ * xuartps_console_write - perform write operation
+ * @port: Handle to the uart port structure
+ * @s: Pointer to character array
+ * @count: No of characters
+ **/
+static void xuartps_console_write(struct console *co, const char *s,
+				unsigned int count)
+{
+	struct uart_port *port = &xuartps_port[co->index];
+	unsigned long flags;
+	unsigned int imr;
+	int locked = 1;
+
+	if (oops_in_progress)
+		locked = spin_trylock_irqsave(&port->lock, flags);
+	else
+		spin_lock_irqsave(&port->lock, flags);
+
+	/* save and disable interrupt */
+	imr = xuartps_readl(XUARTPS_IMR_OFFSET);
+	xuartps_writel(imr, XUARTPS_IDR_OFFSET);
+
+	uart_console_write(port, s, count, xuartps_console_putchar);
+	xuartps_console_wait_tx(port);
+
+	/* restore interrupt state, it seems like there may be a h/w bug
+	 * in that the interrupt enable register should not need to be
+	 * written based on the data sheet
+	 */
+	xuartps_writel(~imr, XUARTPS_IDR_OFFSET);
+	xuartps_writel(imr, XUARTPS_IER_OFFSET);
+
+	if (locked)
+		spin_unlock_irqrestore(&port->lock, flags);
+}
+
+/**
+ * xuartps_console_setup - Initialize the uart to default config
+ * @co: Console handle
+ * @options: Initial settings of uart
+ *
+ * Returns 0, -ENODEV if no device
+ **/
+static int __init xuartps_console_setup(struct console *co, char *options)
+{
+	struct uart_port *port = &xuartps_port[co->index];
+	int baud = 9600;
+	int bits = 8;
+	int parity = 'n';
+	int flow = 'n';
+
+	if (co->index < 0 || co->index >= XUARTPS_NR_PORTS)
+		return -EINVAL;
+
+	if (!port->mapbase) {
+		pr_debug("console on ttyPS%i not present\n", co->index);
+		return -ENODEV;
+	}
+
+	if (options)
+		uart_parse_options(options, &baud, &parity, &bits, &flow);
+
+	return uart_set_options(port, co, baud, parity, bits, flow);
+}
+
+static struct uart_driver xuartps_uart_driver;
+
+static struct console xuartps_console = {
+	.name	= XUARTPS_TTY_NAME,
+	.write	= xuartps_console_write,
+	.device	= uart_console_device,
+	.setup	= xuartps_console_setup,
+	.flags	= CON_PRINTBUFFER,
+	.index	= -1, /* Specified on the cmdline (e.g. console=ttyPS ) */
+	.data	= &xuartps_uart_driver,
+};
+
+/**
+ * xuartps_console_init - Initialization call
+ *
+ * Returns 0 on success, negative error otherwise
+ **/
+static int __init xuartps_console_init(void)
+{
+	register_console(&xuartps_console);
+	return 0;
+}
+
+console_initcall(xuartps_console_init);
+
+#endif /* CONFIG_SERIAL_XILINX_PS_UART_CONSOLE */
+
+/** Structure Definitions
+ */
+static struct uart_driver xuartps_uart_driver = {
+	.owner		= THIS_MODULE,		/* Owner */
+	.driver_name	= XUARTPS_NAME,		/* Driver name */
+	.dev_name	= XUARTPS_TTY_NAME,	/* Node name */
+	.major		= XUARTPS_MAJOR,	/* Major number */
+	.minor		= XUARTPS_MINOR,	/* Minor number */
+	.nr		= XUARTPS_NR_PORTS,	/* Number of UART ports */
+#ifdef CONFIG_SERIAL_XILINX_PS_UART_CONSOLE
+	.cons		= &xuartps_console,	/* Console */
+#endif
+};
+
+/* ---------------------------------------------------------------------
+ * Platform bus binding
+ */
+/**
+ * xuartps_probe - Platform driver probe
+ * @pdev: Pointer to the platform device structure
+ *
+ * Returns 0 on success, negative error otherwise
+ **/
+static int __devinit xuartps_probe(struct platform_device *pdev)
+{
+	int rc;
+	struct uart_port *port;
+	struct resource *res, *res2;
+	int clk = 0;
+
+#ifdef CONFIG_OF
+	const unsigned int *prop;
+
+	prop = of_get_property(pdev->dev.of_node, "clock", NULL);
+	if (prop)
+		clk = be32_to_cpup(prop);
+#else
+	clk = *((unsigned int *)(pdev->dev.platform_data));
+#endif
+	if (!clk) {
+		dev_err(&pdev->dev, "no clock specified\n");
+		return -ENODEV;
+	}
+
+	res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
+	if (!res)
+		return -ENODEV;
+
+	res2 = platform_get_resource(pdev, IORESOURCE_IRQ, 0);
+	if (!res2)
+		return -ENODEV;
+
+	/* Initialize the port structure */
+	port = xuartps_get_port();
+
+	if (!port) {
+		dev_err(&pdev->dev, "Cannot get uart_port structure\n");
+		return -ENODEV;
+	} else {
+		/* Register the port.
+		 * This function also registers this device with the tty layer
+		 * and triggers invocation of the config_port() entry point.
+		 */
+		port->mapbase = res->start;
+		port->irq = res2->start;
+		port->dev = &pdev->dev;
+		port->uartclk = clk;
+		dev_set_drvdata(&pdev->dev, port);
+		rc = uart_add_one_port(&xuartps_uart_driver, port);
+		if (rc) {
+			dev_err(&pdev->dev,
+				"uart_add_one_port() failed; err=%i\n", rc);
+			dev_set_drvdata(&pdev->dev, NULL);
+			return rc;
+		}
+		return 0;
+	}
+}
+
+/**
+ * xuartps_remove - called when the platform driver is unregistered
+ * @pdev: Pointer to the platform device structure
+ *
+ * Returns 0 on success, negative error otherwise
+ **/
+static int __devexit xuartps_remove(struct platform_device *pdev)
+{
+	struct uart_port *port = dev_get_drvdata(&pdev->dev);
+	int rc = 0;
+
+	/* Remove the xuartps port from the serial core */
+	if (port) {
+		rc = uart_remove_one_port(&xuartps_uart_driver, port);
+		dev_set_drvdata(&pdev->dev, NULL);
+		port->mapbase = 0;
+	}
+	return rc;
+}
+
+/**
+ * xuartps_suspend - suspend event
+ * @pdev: Pointer to the platform device structure
+ * @state: State of the device
+ *
+ * Returns 0
+ **/
+static int xuartps_suspend(struct platform_device *pdev, pm_message_t state)
+{
+	/* Call the API provided in serial_core.c file which handles
+	 * the suspend.
+	 */
+	uart_suspend_port(&xuartps_uart_driver, &xuartps_port[pdev->id]);
+	return 0;
+}
+
+/**
+ * xuartps_resume - Resume after a previous suspend
+ * @pdev: Pointer to the platform device structure
+ *
+ * Returns 0
+ **/
+static int xuartps_resume(struct platform_device *pdev)
+{
+	uart_resume_port(&xuartps_uart_driver, &xuartps_port[pdev->id]);
+	return 0;
+}
+
+/* Match table for of_platform binding */
+
+#ifdef CONFIG_OF
+static struct of_device_id xuartps_of_match[] __devinitdata = {
+	{ .compatible = "xlnx,xuartps", },
+	{}
+};
+MODULE_DEVICE_TABLE(of, xuartps_of_match);
+#else
+#define xuartps_of_match NULL
+#endif
+
+static struct platform_driver xuartps_platform_driver = {
+	.probe   = xuartps_probe,		/* Probe method */
+	.remove  = __exit_p(xuartps_remove),	/* Detach method */
+	.suspend = xuartps_suspend,		/* Suspend */
+	.resume  = xuartps_resume,		/* Resume after a suspend */
+	.driver  = {
+		.owner = THIS_MODULE,
+		.name = XUARTPS_NAME,		/* Driver name */
+		.of_match_table = xuartps_of_match,
+		},
+};
+
+/* ---------------------------------------------------------------------
+ * Module Init and Exit
+ */
+/**
+ * xuartps_init - Initial driver registration call
+ *
+ * Returns whether the registration was successful or not
+ **/
+static int __init xuartps_init(void)
+{
+	int retval = 0;
+
+	/* Register the xuartps driver with the serial core */
+	retval = uart_register_driver(&xuartps_uart_driver);
+	if (retval)
+		return retval;
+
+	/* Register the platform driver */
+	retval = platform_driver_register(&xuartps_platform_driver);
+	if (retval)
+		uart_unregister_driver(&xuartps_uart_driver);
+
+	return retval;
+}
+
+/**
+ * xuartps_exit - Driver unregistration call
+ **/
+static void __exit xuartps_exit(void)
+{
+	/* The order of unregistration is important. Unregister the
+	 * UART driver before the platform driver crashes the system.
+	 */
+
+	/* Unregister the platform driver */
+	platform_driver_unregister(&xuartps_platform_driver);
+
+	/* Unregister the xuartps driver */
+	uart_unregister_driver(&xuartps_uart_driver);
+}
+
+module_init(xuartps_init);
+module_exit(xuartps_exit);
+
+MODULE_DESCRIPTION("Driver for PS UART");
+MODULE_AUTHOR("Xilinx Inc.");
+MODULE_LICENSE("GPL");