/*
 * 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.h>
#include <linux/serial_core.h>
#include <linux/tty.h>
#include <linux/tty_flip.h>
#include <linux/console.h>
#include <linux/irq.h>
#include <linux/io.h>
#include <linux/of.h>
#include <linux/module.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");