Merge branch 'fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/evalenti/linux...

[linux/fpc-iii.git] / drivers / tty / serial / xilinx_uartps.c

/*
 * Cadence UART driver (found in Xilinx Zynq)
 *
 * 2011 - 2014 (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.
 *
 * This driver has originally been pushed by Xilinx using a Zynq-branding. This
 * still shows in the naming of this file, the kconfig symbols and some symbols
 * in the code.
 */

#if defined(CONFIG_SERIAL_XILINX_PS_UART_CONSOLE) && defined(CONFIG_MAGIC_SYSRQ)
#define SUPPORT_SYSRQ
#endif

#include <linux/platform_device.h>
#include <linux/serial.h>
#include <linux/console.h>
#include <linux/serial_core.h>
#include <linux/slab.h>
#include <linux/tty.h>
#include <linux/tty_flip.h>
#include <linux/clk.h>
#include <linux/irq.h>
#include <linux/io.h>
#include <linux/of.h>
#include <linux/module.h>

#define CDNS_UART_TTY_NAME      "ttyPS"
#define CDNS_UART_NAME          "xuartps"
#define CDNS_UART_MAJOR         0       /* use dynamic node allocation */
#define CDNS_UART_MINOR         0       /* works best with devtmpfs */
#define CDNS_UART_NR_PORTS      2
#define CDNS_UART_FIFO_SIZE     64      /* FIFO size */
#define CDNS_UART_REGISTER_SPACE        0x1000

/* Rx Trigger level */
static int rx_trigger_level = 56;
module_param(rx_trigger_level, uint, S_IRUGO);
MODULE_PARM_DESC(rx_trigger_level, "Rx trigger level, 1-63 bytes");

/* Rx Timeout */
static int rx_timeout = 10;
module_param(rx_timeout, uint, S_IRUGO);
MODULE_PARM_DESC(rx_timeout, "Rx timeout, 1-255");

/* Register offsets for the UART. */
#define CDNS_UART_CR            0x00  /* Control Register */
#define CDNS_UART_MR            0x04  /* Mode Register */
#define CDNS_UART_IER           0x08  /* Interrupt Enable */
#define CDNS_UART_IDR           0x0C  /* Interrupt Disable */
#define CDNS_UART_IMR           0x10  /* Interrupt Mask */
#define CDNS_UART_ISR           0x14  /* Interrupt Status */
#define CDNS_UART_BAUDGEN       0x18  /* Baud Rate Generator */
#define CDNS_UART_RXTOUT                0x1C  /* RX Timeout */
#define CDNS_UART_RXWM          0x20  /* RX FIFO Trigger Level */
#define CDNS_UART_MODEMCR       0x24  /* Modem Control */
#define CDNS_UART_MODEMSR       0x28  /* Modem Status */
#define CDNS_UART_SR            0x2C  /* Channel Status */
#define CDNS_UART_FIFO          0x30  /* FIFO */
#define CDNS_UART_BAUDDIV       0x34  /* Baud Rate Divider */
#define CDNS_UART_FLOWDEL       0x38  /* Flow Delay */
#define CDNS_UART_IRRX_PWIDTH   0x3C  /* IR Min Received Pulse Width */
#define CDNS_UART_IRTX_PWIDTH   0x40  /* IR Transmitted pulse Width */
#define CDNS_UART_TXWM          0x44  /* TX FIFO Trigger Level */

/* Control Register Bit Definitions */
#define CDNS_UART_CR_STOPBRK    0x00000100  /* Stop TX break */
#define CDNS_UART_CR_STARTBRK   0x00000080  /* Set TX break */
#define CDNS_UART_CR_TX_DIS     0x00000020  /* TX disabled. */
#define CDNS_UART_CR_TX_EN      0x00000010  /* TX enabled */
#define CDNS_UART_CR_RX_DIS     0x00000008  /* RX disabled. */
#define CDNS_UART_CR_RX_EN      0x00000004  /* RX enabled */
#define CDNS_UART_CR_TXRST      0x00000002  /* TX logic reset */
#define CDNS_UART_CR_RXRST      0x00000001  /* RX logic reset */
#define CDNS_UART_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.
 */
#define CDNS_UART_MR_CLKSEL             0x00000001  /* Pre-scalar selection */
#define CDNS_UART_MR_CHMODE_L_LOOP      0x00000200  /* Local loop back mode */
#define CDNS_UART_MR_CHMODE_NORM        0x00000000  /* Normal mode */

#define CDNS_UART_MR_STOPMODE_2_BIT     0x00000080  /* 2 stop bits */
#define CDNS_UART_MR_STOPMODE_1_BIT     0x00000000  /* 1 stop bit */

#define CDNS_UART_MR_PARITY_NONE        0x00000020  /* No parity mode */
#define CDNS_UART_MR_PARITY_MARK        0x00000018  /* Mark parity mode */
#define CDNS_UART_MR_PARITY_SPACE       0x00000010  /* Space parity mode */
#define CDNS_UART_MR_PARITY_ODD         0x00000008  /* Odd parity mode */
#define CDNS_UART_MR_PARITY_EVEN        0x00000000  /* Even parity mode */

#define CDNS_UART_MR_CHARLEN_6_BIT      0x00000006  /* 6 bits data */
#define CDNS_UART_MR_CHARLEN_7_BIT      0x00000004  /* 7 bits data */
#define CDNS_UART_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 CDNS_UART_IXR_TOUT      0x00000100 /* RX Timeout error interrupt */
#define CDNS_UART_IXR_PARITY    0x00000080 /* Parity error interrupt */
#define CDNS_UART_IXR_FRAMING   0x00000040 /* Framing error interrupt */
#define CDNS_UART_IXR_OVERRUN   0x00000020 /* Overrun error interrupt */
#define CDNS_UART_IXR_TXFULL    0x00000010 /* TX FIFO Full interrupt */
#define CDNS_UART_IXR_TXEMPTY   0x00000008 /* TX FIFO empty interrupt */
#define CDNS_UART_ISR_RXEMPTY   0x00000002 /* RX FIFO empty interrupt */
#define CDNS_UART_IXR_RXTRIG    0x00000001 /* RX FIFO trigger interrupt */
#define CDNS_UART_IXR_RXFULL    0x00000004 /* RX FIFO full interrupt. */
#define CDNS_UART_IXR_RXEMPTY   0x00000002 /* RX FIFO empty interrupt. */
#define CDNS_UART_IXR_MASK      0x00001FFF /* Valid bit mask */

#define CDNS_UART_RX_IRQS       (CDNS_UART_IXR_PARITY | CDNS_UART_IXR_FRAMING | \
                                 CDNS_UART_IXR_OVERRUN | CDNS_UART_IXR_RXTRIG | \
                                 CDNS_UART_IXR_TOUT)

/* Goes in read_status_mask for break detection as the HW doesn't do it*/
#define CDNS_UART_IXR_BRK       0x80000000

/*
 * Modem Control register:
 * The read/write Modem Control register controls the interface with the modem
 * or data set, or a peripheral device emulating a modem.
 */
#define CDNS_UART_MODEMCR_FCM   0x00000020 /* Automatic flow control mode */
#define CDNS_UART_MODEMCR_RTS   0x00000002 /* Request to send output control */
#define CDNS_UART_MODEMCR_DTR   0x00000001 /* Data Terminal Ready */

/*
 * 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 CDNS_UART_SR_RXEMPTY    0x00000002 /* RX FIFO empty */
#define CDNS_UART_SR_TXEMPTY    0x00000008 /* TX FIFO empty */
#define CDNS_UART_SR_TXFULL     0x00000010 /* TX FIFO full */
#define CDNS_UART_SR_RXTRIG     0x00000001 /* Rx Trigger */

/* baud dividers min/max values */
#define CDNS_UART_BDIV_MIN      4
#define CDNS_UART_BDIV_MAX      255
#define CDNS_UART_CD_MAX        65535

/**
 * struct cdns_uart - device data
 * @port:               Pointer to the UART port
 * @uartclk:            Reference clock
 * @pclk:               APB clock
 * @baud:               Current baud rate
 * @clk_rate_change_nb: Notifier block for clock changes
 */
struct cdns_uart {
        struct uart_port        *port;
        struct clk              *uartclk;
        struct clk              *pclk;
        unsigned int            baud;
        struct notifier_block   clk_rate_change_nb;
};
#define to_cdns_uart(_nb) container_of(_nb, struct cdns_uart, \
                clk_rate_change_nb);

static void cdns_uart_handle_rx(struct uart_port *port, unsigned int isrstatus)
{
        /*
         * There is no hardware break detection, so we interpret framing
         * error with all-zeros data as a break sequence. Most of the time,
         * there's another non-zero byte at the end of the sequence.
         */
        if (isrstatus & CDNS_UART_IXR_FRAMING) {
                while (!(readl(port->membase + CDNS_UART_SR) &
                                        CDNS_UART_SR_RXEMPTY)) {
                        if (!readl(port->membase + CDNS_UART_FIFO)) {
                                port->read_status_mask |= CDNS_UART_IXR_BRK;
                                isrstatus &= ~CDNS_UART_IXR_FRAMING;
                        }
                }
                writel(CDNS_UART_IXR_FRAMING, port->membase + CDNS_UART_ISR);
        }

        /* drop byte with parity error if IGNPAR specified */
        if (isrstatus & port->ignore_status_mask & CDNS_UART_IXR_PARITY)
                isrstatus &= ~(CDNS_UART_IXR_RXTRIG | CDNS_UART_IXR_TOUT);

        isrstatus &= port->read_status_mask;
        isrstatus &= ~port->ignore_status_mask;

        if (!(isrstatus & (CDNS_UART_IXR_TOUT | CDNS_UART_IXR_RXTRIG)))
                return;

        while (!(readl(port->membase + CDNS_UART_SR) & CDNS_UART_SR_RXEMPTY)) {
                u32 data;
                char status = TTY_NORMAL;

                data = readl(port->membase + CDNS_UART_FIFO);

                /* Non-NULL byte after BREAK is garbage (99%) */
                if (data && (port->read_status_mask & CDNS_UART_IXR_BRK)) {
                        port->read_status_mask &= ~CDNS_UART_IXR_BRK;
                        port->icount.brk++;
                        if (uart_handle_break(port))
                                continue;
                }

                if (uart_handle_sysrq_char(port, data))
                        continue;

                port->icount.rx++;

                if (isrstatus & CDNS_UART_IXR_PARITY) {
                        port->icount.parity++;
                        status = TTY_PARITY;
                } else if (isrstatus & CDNS_UART_IXR_FRAMING) {
                        port->icount.frame++;
                        status = TTY_FRAME;
                } else if (isrstatus & CDNS_UART_IXR_OVERRUN) {
                        port->icount.overrun++;
                }

                uart_insert_char(port, isrstatus, CDNS_UART_IXR_OVERRUN,
                                 data, status);
        }
        tty_flip_buffer_push(&port->state->port);
}

static void cdns_uart_handle_tx(struct uart_port *port)
{
        unsigned int numbytes;

        if (uart_circ_empty(&port->state->xmit)) {
                writel(CDNS_UART_IXR_TXEMPTY, port->membase + CDNS_UART_IDR);
                return;
        }

        numbytes = port->fifosize;
        while (numbytes && !uart_circ_empty(&port->state->xmit) &&
               !(readl(port->membase + CDNS_UART_SR) & CDNS_UART_SR_TXFULL)) {
                /*
                 * Get the data from the UART circular buffer
                 * and write it to the cdns_uart's TX_FIFO
                 * register.
                 */
                writel(port->state->xmit.buf[port->state->xmit.tail],
                        port->membase + CDNS_UART_FIFO);
                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);

                numbytes--;
        }

        if (uart_circ_chars_pending(&port->state->xmit) < WAKEUP_CHARS)
                uart_write_wakeup(port);
}

/**
 * cdns_uart_isr - Interrupt handler
 * @irq: Irq number
 * @dev_id: Id of the port
 *
 * Return: IRQHANDLED
 */
static irqreturn_t cdns_uart_isr(int irq, void *dev_id)
{
        struct uart_port *port = (struct uart_port *)dev_id;
        unsigned long flags;
        unsigned int isrstatus;

        spin_lock_irqsave(&port->lock, flags);

        /* Read the interrupt status register to determine which
         * interrupt(s) is/are active.
         */
        isrstatus = readl(port->membase + CDNS_UART_ISR);

        if (isrstatus & CDNS_UART_RX_IRQS)
                cdns_uart_handle_rx(port, isrstatus);

        if ((isrstatus & CDNS_UART_IXR_TXEMPTY) == CDNS_UART_IXR_TXEMPTY)
                cdns_uart_handle_tx(port);

        writel(isrstatus, port->membase + CDNS_UART_ISR);

        /* be sure to release the lock and tty before leaving */
        spin_unlock_irqrestore(&port->lock, flags);

        return IRQ_HANDLED;
}

/**
 * cdns_uart_calc_baud_divs - Calculate baud rate divisors
 * @clk: UART module input clock
 * @baud: Desired baud rate
 * @rbdiv: BDIV value (return value)
 * @rcd: CD value (return value)
 * @div8: Value for clk_sel bit in mod (return value)
 * Return: baud rate, requested baud when possible, or actual baud when there
 *      was too much error, zero if no valid divisors are found.
 *
 * Formula to obtain baud rate is
 *      baud_tx/rx rate = clk/CD * (BDIV + 1)
 *      input_clk = (Uart User Defined Clock or Apb Clock)
 *              depends on UCLKEN in MR Reg
 *      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
 */
static unsigned int cdns_uart_calc_baud_divs(unsigned int clk,
                unsigned int baud, u32 *rbdiv, u32 *rcd, int *div8)
{
        u32 cd, bdiv;
        unsigned int calc_baud;
        unsigned int bestbaud = 0;
        unsigned int bauderror;
        unsigned int besterror = ~0;

        if (baud < clk / ((CDNS_UART_BDIV_MAX + 1) * CDNS_UART_CD_MAX)) {
                *div8 = 1;
                clk /= 8;
        } else {
                *div8 = 0;
        }

        for (bdiv = CDNS_UART_BDIV_MIN; bdiv <= CDNS_UART_BDIV_MAX; bdiv++) {
                cd = DIV_ROUND_CLOSEST(clk, baud * (bdiv + 1));
                if (cd < 1 || cd > CDNS_UART_CD_MAX)
                        continue;

                calc_baud = clk / (cd * (bdiv + 1));

                if (baud > calc_baud)
                        bauderror = baud - calc_baud;
                else
                        bauderror = calc_baud - baud;

                if (besterror > bauderror) {
                        *rbdiv = bdiv;
                        *rcd = cd;
                        bestbaud = calc_baud;
                        besterror = bauderror;
                }
        }
        /* use the values when percent error is acceptable */
        if (((besterror * 100) / baud) < 3)
                bestbaud = baud;

        return bestbaud;
}

/**
 * cdns_uart_set_baud_rate - Calculate and set the baud rate
 * @port: Handle to the uart port structure
 * @baud: Baud rate to set
 * Return: baud rate, requested baud when possible, or actual baud when there
 *         was too much error, zero if no valid divisors are found.
 */
static unsigned int cdns_uart_set_baud_rate(struct uart_port *port,
                unsigned int baud)
{
        unsigned int calc_baud;
        u32 cd = 0, bdiv = 0;
        u32 mreg;
        int div8;
        struct cdns_uart *cdns_uart = port->private_data;

        calc_baud = cdns_uart_calc_baud_divs(port->uartclk, baud, &bdiv, &cd,
                        &div8);

        /* Write new divisors to hardware */
        mreg = readl(port->membase + CDNS_UART_MR);
        if (div8)
                mreg |= CDNS_UART_MR_CLKSEL;
        else
                mreg &= ~CDNS_UART_MR_CLKSEL;
        writel(mreg, port->membase + CDNS_UART_MR);
        writel(cd, port->membase + CDNS_UART_BAUDGEN);
        writel(bdiv, port->membase + CDNS_UART_BAUDDIV);
        cdns_uart->baud = baud;

        return calc_baud;
}

#ifdef CONFIG_COMMON_CLK
/**
 * cdns_uart_clk_notitifer_cb - Clock notifier callback
 * @nb:         Notifier block
 * @event:      Notify event
 * @data:       Notifier data
 * Return:      NOTIFY_OK or NOTIFY_DONE on success, NOTIFY_BAD on error.
 */
static int cdns_uart_clk_notifier_cb(struct notifier_block *nb,
                unsigned long event, void *data)
{
        u32 ctrl_reg;
        struct uart_port *port;
        int locked = 0;
        struct clk_notifier_data *ndata = data;
        unsigned long flags = 0;
        struct cdns_uart *cdns_uart = to_cdns_uart(nb);

        port = cdns_uart->port;
        if (port->suspended)
                return NOTIFY_OK;

        switch (event) {
        case PRE_RATE_CHANGE:
        {
                u32 bdiv, cd;
                int div8;

                /*
                 * Find out if current baud-rate can be achieved with new clock
                 * frequency.
                 */
                if (!cdns_uart_calc_baud_divs(ndata->new_rate, cdns_uart->baud,
                                        &bdiv, &cd, &div8)) {
                        dev_warn(port->dev, "clock rate change rejected\n");
                        return NOTIFY_BAD;
                }

                spin_lock_irqsave(&cdns_uart->port->lock, flags);

                /* Disable the TX and RX to set baud rate */
                ctrl_reg = readl(port->membase + CDNS_UART_CR);
                ctrl_reg |= CDNS_UART_CR_TX_DIS | CDNS_UART_CR_RX_DIS;
                writel(ctrl_reg, port->membase + CDNS_UART_CR);

                spin_unlock_irqrestore(&cdns_uart->port->lock, flags);

                return NOTIFY_OK;
        }
        case POST_RATE_CHANGE:
                /*
                 * Set clk dividers to generate correct baud with new clock
                 * frequency.
                 */

                spin_lock_irqsave(&cdns_uart->port->lock, flags);

                locked = 1;
                port->uartclk = ndata->new_rate;

                cdns_uart->baud = cdns_uart_set_baud_rate(cdns_uart->port,
                                cdns_uart->baud);
                /* fall through */
        case ABORT_RATE_CHANGE:
                if (!locked)
                        spin_lock_irqsave(&cdns_uart->port->lock, flags);

                /* Set TX/RX Reset */
                ctrl_reg = readl(port->membase + CDNS_UART_CR);
                ctrl_reg |= CDNS_UART_CR_TXRST | CDNS_UART_CR_RXRST;
                writel(ctrl_reg, port->membase + CDNS_UART_CR);

                while (readl(port->membase + CDNS_UART_CR) &
                                (CDNS_UART_CR_TXRST | CDNS_UART_CR_RXRST))
                        cpu_relax();

                /*
                 * 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.
                 */
                writel(rx_timeout, port->membase + CDNS_UART_RXTOUT);
                ctrl_reg = readl(port->membase + CDNS_UART_CR);
                ctrl_reg &= ~(CDNS_UART_CR_TX_DIS | CDNS_UART_CR_RX_DIS);
                ctrl_reg |= CDNS_UART_CR_TX_EN | CDNS_UART_CR_RX_EN;
                writel(ctrl_reg, port->membase + CDNS_UART_CR);

                spin_unlock_irqrestore(&cdns_uart->port->lock, flags);

                return NOTIFY_OK;
        default:
                return NOTIFY_DONE;
        }
}
#endif

/**
 * cdns_uart_start_tx -  Start transmitting bytes
 * @port: Handle to the uart port structure
 */
static void cdns_uart_start_tx(struct uart_port *port)
{
        unsigned int status;

        if (uart_tx_stopped(port))
                return;

        /*
         * Set the TX enable bit and clear the TX disable bit to enable the
         * transmitter.
         */
        status = readl(port->membase + CDNS_UART_CR);
        status &= ~CDNS_UART_CR_TX_DIS;
        status |= CDNS_UART_CR_TX_EN;
        writel(status, port->membase + CDNS_UART_CR);

        if (uart_circ_empty(&port->state->xmit))
                return;

        cdns_uart_handle_tx(port);

        writel(CDNS_UART_IXR_TXEMPTY, port->membase + CDNS_UART_ISR);
        /* Enable the TX Empty interrupt */
        writel(CDNS_UART_IXR_TXEMPTY, port->membase + CDNS_UART_IER);
}

/**
 * cdns_uart_stop_tx - Stop TX
 * @port: Handle to the uart port structure
 */
static void cdns_uart_stop_tx(struct uart_port *port)
{
        unsigned int regval;

        regval = readl(port->membase + CDNS_UART_CR);
        regval |= CDNS_UART_CR_TX_DIS;
        /* Disable the transmitter */
        writel(regval, port->membase + CDNS_UART_CR);
}

/**
 * cdns_uart_stop_rx - Stop RX
 * @port: Handle to the uart port structure
 */
static void cdns_uart_stop_rx(struct uart_port *port)
{
        unsigned int regval;

        /* Disable RX IRQs */
        writel(CDNS_UART_RX_IRQS, port->membase + CDNS_UART_IDR);

        /* Disable the receiver */
        regval = readl(port->membase + CDNS_UART_CR);
        regval |= CDNS_UART_CR_RX_DIS;
        writel(regval, port->membase + CDNS_UART_CR);
}

/**
 * cdns_uart_tx_empty -  Check whether TX is empty
 * @port: Handle to the uart port structure
 *
 * Return: TIOCSER_TEMT on success, 0 otherwise
 */
static unsigned int cdns_uart_tx_empty(struct uart_port *port)
{
        unsigned int status;

        status = readl(port->membase + CDNS_UART_SR) &
                                CDNS_UART_SR_TXEMPTY;
        return status ? TIOCSER_TEMT : 0;
}

/**
 * cdns_uart_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 cdns_uart_break_ctl(struct uart_port *port, int ctl)
{
        unsigned int status;
        unsigned long flags;

        spin_lock_irqsave(&port->lock, flags);

        status = readl(port->membase + CDNS_UART_CR);

        if (ctl == -1)
                writel(CDNS_UART_CR_STARTBRK | status,
                                port->membase + CDNS_UART_CR);
        else {
                if ((status & CDNS_UART_CR_STOPBRK) == 0)
                        writel(CDNS_UART_CR_STOPBRK | status,
                                        port->membase + CDNS_UART_CR);
        }
        spin_unlock_irqrestore(&port->lock, flags);
}

/**
 * cdns_uart_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 cdns_uart_set_termios(struct uart_port *port,
                                struct ktermios *termios, struct ktermios *old)
{
        unsigned int cval = 0;
        unsigned int baud, minbaud, maxbaud;
        unsigned long flags;
        unsigned int ctrl_reg, mode_reg;

        spin_lock_irqsave(&port->lock, flags);

        /* Wait for the transmit FIFO to empty before making changes */
        if (!(readl(port->membase + CDNS_UART_CR) &
                                CDNS_UART_CR_TX_DIS)) {
                while (!(readl(port->membase + CDNS_UART_SR) &
                                CDNS_UART_SR_TXEMPTY)) {
                        cpu_relax();
                }
        }

        /* Disable the TX and RX to set baud rate */
        ctrl_reg = readl(port->membase + CDNS_UART_CR);
        ctrl_reg |= CDNS_UART_CR_TX_DIS | CDNS_UART_CR_RX_DIS;
        writel(ctrl_reg, port->membase + CDNS_UART_CR);

        /*
         * Min baud rate = 6bps and Max Baud Rate is 10Mbps for 100Mhz clk
         * min and max baud should be calculated here based on port->uartclk.
         * this way we get a valid baud and can safely call set_baud()
         */
        minbaud = port->uartclk /
                        ((CDNS_UART_BDIV_MAX + 1) * CDNS_UART_CD_MAX * 8);
        maxbaud = port->uartclk / (CDNS_UART_BDIV_MIN + 1);
        baud = uart_get_baud_rate(port, termios, old, minbaud, maxbaud);
        baud = cdns_uart_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 */
        ctrl_reg = readl(port->membase + CDNS_UART_CR);
        ctrl_reg |= CDNS_UART_CR_TXRST | CDNS_UART_CR_RXRST;
        writel(ctrl_reg, port->membase + CDNS_UART_CR);

        /*
         * 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.
         */
        ctrl_reg = readl(port->membase + CDNS_UART_CR);
        ctrl_reg &= ~(CDNS_UART_CR_TX_DIS | CDNS_UART_CR_RX_DIS);
        ctrl_reg |= CDNS_UART_CR_TX_EN | CDNS_UART_CR_RX_EN;
        writel(ctrl_reg, port->membase + CDNS_UART_CR);

        writel(rx_timeout, port->membase + CDNS_UART_RXTOUT);

        port->read_status_mask = CDNS_UART_IXR_TXEMPTY | CDNS_UART_IXR_RXTRIG |
                        CDNS_UART_IXR_OVERRUN | CDNS_UART_IXR_TOUT;
        port->ignore_status_mask = 0;

        if (termios->c_iflag & INPCK)
                port->read_status_mask |= CDNS_UART_IXR_PARITY |
                CDNS_UART_IXR_FRAMING;

        if (termios->c_iflag & IGNPAR)
                port->ignore_status_mask |= CDNS_UART_IXR_PARITY |
                        CDNS_UART_IXR_FRAMING | CDNS_UART_IXR_OVERRUN;

        /* ignore all characters if CREAD is not set */
        if ((termios->c_cflag & CREAD) == 0)
                port->ignore_status_mask |= CDNS_UART_IXR_RXTRIG |
                        CDNS_UART_IXR_TOUT | CDNS_UART_IXR_PARITY |
                        CDNS_UART_IXR_FRAMING | CDNS_UART_IXR_OVERRUN;

        mode_reg = readl(port->membase + CDNS_UART_MR);

        /* Handling Data Size */
        switch (termios->c_cflag & CSIZE) {
        case CS6:
                cval |= CDNS_UART_MR_CHARLEN_6_BIT;
                break;
        case CS7:
                cval |= CDNS_UART_MR_CHARLEN_7_BIT;
                break;
        default:
        case CS8:
                cval |= CDNS_UART_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 |= CDNS_UART_MR_STOPMODE_2_BIT; /* 2 STOP bits */
        else
                cval |= CDNS_UART_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 |= CDNS_UART_MR_PARITY_MARK;
                        else
                                cval |= CDNS_UART_MR_PARITY_SPACE;
                } else {
                        if (termios->c_cflag & PARODD)
                                cval |= CDNS_UART_MR_PARITY_ODD;
                        else
                                cval |= CDNS_UART_MR_PARITY_EVEN;
                }
        } else {
                cval |= CDNS_UART_MR_PARITY_NONE;
        }
        cval |= mode_reg & 1;
        writel(cval, port->membase + CDNS_UART_MR);

        spin_unlock_irqrestore(&port->lock, flags);
}

/**
 * cdns_uart_startup - Called when an application opens a cdns_uart port
 * @port: Handle to the uart port structure
 *
 * Return: 0 on success, negative errno otherwise
 */
static int cdns_uart_startup(struct uart_port *port)
{
        int ret;
        unsigned long flags;
        unsigned int status = 0;

        spin_lock_irqsave(&port->lock, flags);

        /* Disable the TX and RX */
        writel(CDNS_UART_CR_TX_DIS | CDNS_UART_CR_RX_DIS,
                        port->membase + CDNS_UART_CR);

        /* Set the Control Register with TX/RX Enable, TX/RX Reset,
         * no break chars.
         */
        writel(CDNS_UART_CR_TXRST | CDNS_UART_CR_RXRST,
                        port->membase + CDNS_UART_CR);

        /*
         * Clear the RX disable bit and then set the RX enable bit to enable
         * the receiver.
         */
        status = readl(port->membase + CDNS_UART_CR);
        status &= CDNS_UART_CR_RX_DIS;
        status |= CDNS_UART_CR_RX_EN;
        writel(status, port->membase + CDNS_UART_CR);

        /* Set the Mode Register with normal mode,8 data bits,1 stop bit,
         * no parity.
         */
        writel(CDNS_UART_MR_CHMODE_NORM | CDNS_UART_MR_STOPMODE_1_BIT
                | CDNS_UART_MR_PARITY_NONE | CDNS_UART_MR_CHARLEN_8_BIT,
                port->membase + CDNS_UART_MR);

        /*
         * Set the RX FIFO Trigger level to use most of the FIFO, but it
         * can be tuned with a module parameter
         */
        writel(rx_trigger_level, port->membase + CDNS_UART_RXWM);

        /*
         * Receive Timeout register is enabled but it
         * can be tuned with a module parameter
         */
        writel(rx_timeout, port->membase + CDNS_UART_RXTOUT);

        /* Clear out any pending interrupts before enabling them */
        writel(readl(port->membase + CDNS_UART_ISR),
                        port->membase + CDNS_UART_ISR);

        spin_unlock_irqrestore(&port->lock, flags);

        ret = request_irq(port->irq, cdns_uart_isr, 0, CDNS_UART_NAME, port);
        if (ret) {
                dev_err(port->dev, "request_irq '%d' failed with %d\n",
                        port->irq, ret);
                return ret;
        }

        /* Set the Interrupt Registers with desired interrupts */
        writel(CDNS_UART_RX_IRQS, port->membase + CDNS_UART_IER);

        return 0;
}

/**
 * cdns_uart_shutdown - Called when an application closes a cdns_uart port
 * @port: Handle to the uart port structure
 */
static void cdns_uart_shutdown(struct uart_port *port)
{
        int status;
        unsigned long flags;

        spin_lock_irqsave(&port->lock, flags);

        /* Disable interrupts */
        status = readl(port->membase + CDNS_UART_IMR);
        writel(status, port->membase + CDNS_UART_IDR);
        writel(0xffffffff, port->membase + CDNS_UART_ISR);

        /* Disable the TX and RX */
        writel(CDNS_UART_CR_TX_DIS | CDNS_UART_CR_RX_DIS,
                        port->membase + CDNS_UART_CR);

        spin_unlock_irqrestore(&port->lock, flags);

        free_irq(port->irq, port);
}

/**
 * cdns_uart_type - Set UART type to cdns_uart port
 * @port: Handle to the uart port structure
 *
 * Return: string on success, NULL otherwise
 */
static const char *cdns_uart_type(struct uart_port *port)
{
        return port->type == PORT_XUARTPS ? CDNS_UART_NAME : NULL;
}

/**
 * cdns_uart_verify_port - Verify the port params
 * @port: Handle to the uart port structure
 * @ser: Handle to the structure whose members are compared
 *
 * Return: 0 on success, negative errno otherwise.
 */
static int cdns_uart_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;
}

/**
 * cdns_uart_request_port - Claim the memory region attached to cdns_uart port,
 *                              called when the driver adds a cdns_uart port via
 *                              uart_add_one_port()
 * @port: Handle to the uart port structure
 *
 * Return: 0 on success, negative errno otherwise.
 */
static int cdns_uart_request_port(struct uart_port *port)
{
        if (!request_mem_region(port->mapbase, CDNS_UART_REGISTER_SPACE,
                                         CDNS_UART_NAME)) {
                return -ENOMEM;
        }

        port->membase = ioremap(port->mapbase, CDNS_UART_REGISTER_SPACE);
        if (!port->membase) {
                dev_err(port->dev, "Unable to map registers\n");
                release_mem_region(port->mapbase, CDNS_UART_REGISTER_SPACE);
                return -ENOMEM;
        }
        return 0;
}

/**
 * cdns_uart_release_port - Release UART port
 * @port: Handle to the uart port structure
 *
 * Release the memory region attached to a cdns_uart port. Called when the
 * driver removes a cdns_uart port via uart_remove_one_port().
 */
static void cdns_uart_release_port(struct uart_port *port)
{
        release_mem_region(port->mapbase, CDNS_UART_REGISTER_SPACE);
        iounmap(port->membase);
        port->membase = NULL;
}

/**
 * cdns_uart_config_port - Configure UART port
 * @port: Handle to the uart port structure
 * @flags: If any
 */
static void cdns_uart_config_port(struct uart_port *port, int flags)
{
        if (flags & UART_CONFIG_TYPE && cdns_uart_request_port(port) == 0)
                port->type = PORT_XUARTPS;
}

/**
 * cdns_uart_get_mctrl - Get the modem control state
 * @port: Handle to the uart port structure
 *
 * Return: the modem control state
 */
static unsigned int cdns_uart_get_mctrl(struct uart_port *port)
{
        return TIOCM_CTS | TIOCM_DSR | TIOCM_CAR;
}

static void cdns_uart_set_mctrl(struct uart_port *port, unsigned int mctrl)
{
        u32 val;

        val = readl(port->membase + CDNS_UART_MODEMCR);

        val &= ~(CDNS_UART_MODEMCR_RTS | CDNS_UART_MODEMCR_DTR);

        if (mctrl & TIOCM_RTS)
                val |= CDNS_UART_MODEMCR_RTS;
        if (mctrl & TIOCM_DTR)
                val |= CDNS_UART_MODEMCR_DTR;

        writel(val, port->membase + CDNS_UART_MODEMCR);
}

#ifdef CONFIG_CONSOLE_POLL
static int cdns_uart_poll_get_char(struct uart_port *port)
{
        int c;
        unsigned long flags;

        spin_lock_irqsave(&port->lock, flags);

        /* Check if FIFO is empty */
        if (readl(port->membase + CDNS_UART_SR) & CDNS_UART_SR_RXEMPTY)
                c = NO_POLL_CHAR;
        else /* Read a character */
                c = (unsigned char) readl(port->membase + CDNS_UART_FIFO);

        spin_unlock_irqrestore(&port->lock, flags);

        return c;
}

static void cdns_uart_poll_put_char(struct uart_port *port, unsigned char c)
{
        unsigned long flags;

        spin_lock_irqsave(&port->lock, flags);

        /* Wait until FIFO is empty */
        while (!(readl(port->membase + CDNS_UART_SR) & CDNS_UART_SR_TXEMPTY))
                cpu_relax();

        /* Write a character */
        writel(c, port->membase + CDNS_UART_FIFO);

        /* Wait until FIFO is empty */
        while (!(readl(port->membase + CDNS_UART_SR) & CDNS_UART_SR_TXEMPTY))
                cpu_relax();

        spin_unlock_irqrestore(&port->lock, flags);

        return;
}
#endif

static struct uart_ops cdns_uart_ops = {
        .set_mctrl      = cdns_uart_set_mctrl,
        .get_mctrl      = cdns_uart_get_mctrl,
        .start_tx       = cdns_uart_start_tx,
        .stop_tx        = cdns_uart_stop_tx,
        .stop_rx        = cdns_uart_stop_rx,
        .tx_empty       = cdns_uart_tx_empty,
        .break_ctl      = cdns_uart_break_ctl,
        .set_termios    = cdns_uart_set_termios,
        .startup        = cdns_uart_startup,
        .shutdown       = cdns_uart_shutdown,
        .type           = cdns_uart_type,
        .verify_port    = cdns_uart_verify_port,
        .request_port   = cdns_uart_request_port,
        .release_port   = cdns_uart_release_port,
        .config_port    = cdns_uart_config_port,
#ifdef CONFIG_CONSOLE_POLL
        .poll_get_char  = cdns_uart_poll_get_char,
        .poll_put_char  = cdns_uart_poll_put_char,
#endif
};

static struct uart_port cdns_uart_port[CDNS_UART_NR_PORTS];

/**
 * cdns_uart_get_port - Configure the port from platform device resource info
 * @id: Port id
 *
 * Return: a pointer to a uart_port or NULL for failure
 */
static struct uart_port *cdns_uart_get_port(int id)
{
        struct uart_port *port;

        /* Try the given port id if failed use default method */
        if (cdns_uart_port[id].mapbase != 0) {
                /* Find the next unused port */
                for (id = 0; id < CDNS_UART_NR_PORTS; id++)
                        if (cdns_uart_port[id].mapbase == 0)
                                break;
        }

        if (id >= CDNS_UART_NR_PORTS)
                return NULL;

        port = &cdns_uart_port[id];

        /* At this point, we've got an empty uart_port struct, initialize it */
        spin_lock_init(&port->lock);
        port->membase   = NULL;
        port->irq       = 0;
        port->type      = PORT_UNKNOWN;
        port->iotype    = UPIO_MEM32;
        port->flags     = UPF_BOOT_AUTOCONF;
        port->ops       = &cdns_uart_ops;
        port->fifosize  = CDNS_UART_FIFO_SIZE;
        port->line      = id;
        port->dev       = NULL;
        return port;
}

#ifdef CONFIG_SERIAL_XILINX_PS_UART_CONSOLE
/**
 * cdns_uart_console_wait_tx - Wait for the TX to be full
 * @port: Handle to the uart port structure
 */
static void cdns_uart_console_wait_tx(struct uart_port *port)
{
        while (!(readl(port->membase + CDNS_UART_SR) & CDNS_UART_SR_TXEMPTY))
                barrier();
}

/**
 * cdns_uart_console_putchar - write the character to the FIFO buffer
 * @port: Handle to the uart port structure
 * @ch: Character to be written
 */
static void cdns_uart_console_putchar(struct uart_port *port, int ch)
{
        cdns_uart_console_wait_tx(port);
        writel(ch, port->membase + CDNS_UART_FIFO);
}

static void __init cdns_early_write(struct console *con, const char *s,
                                    unsigned n)
{
        struct earlycon_device *dev = con->data;

        uart_console_write(&dev->port, s, n, cdns_uart_console_putchar);
}

static int __init cdns_early_console_setup(struct earlycon_device *device,
                                           const char *opt)
{
        if (!device->port.membase)
                return -ENODEV;

        device->con->write = cdns_early_write;

        return 0;
}
OF_EARLYCON_DECLARE(cdns, "xlnx,xuartps", cdns_early_console_setup);
OF_EARLYCON_DECLARE(cdns, "cdns,uart-r1p8", cdns_early_console_setup);
OF_EARLYCON_DECLARE(cdns, "cdns,uart-r1p12", cdns_early_console_setup);

/**
 * cdns_uart_console_write - perform write operation
 * @co: Console handle
 * @s: Pointer to character array
 * @count: No of characters
 */
static void cdns_uart_console_write(struct console *co, const char *s,
                                unsigned int count)
{
        struct uart_port *port = &cdns_uart_port[co->index];
        unsigned long flags;
        unsigned int imr, ctrl;
        int locked = 1;

        if (port->sysrq)
                locked = 0;
        else if (oops_in_progress)
                locked = spin_trylock_irqsave(&port->lock, flags);
        else
                spin_lock_irqsave(&port->lock, flags);

        /* save and disable interrupt */
        imr = readl(port->membase + CDNS_UART_IMR);
        writel(imr, port->membase + CDNS_UART_IDR);

        /*
         * Make sure that the tx part is enabled. Set the TX enable bit and
         * clear the TX disable bit to enable the transmitter.
         */
        ctrl = readl(port->membase + CDNS_UART_CR);
        ctrl &= ~CDNS_UART_CR_TX_DIS;
        ctrl |= CDNS_UART_CR_TX_EN;
        writel(ctrl, port->membase + CDNS_UART_CR);

        uart_console_write(port, s, count, cdns_uart_console_putchar);
        cdns_uart_console_wait_tx(port);

        writel(ctrl, port->membase + CDNS_UART_CR);

        /* restore interrupt state */
        writel(imr, port->membase + CDNS_UART_IER);

        if (locked)
                spin_unlock_irqrestore(&port->lock, flags);
}

/**
 * cdns_uart_console_setup - Initialize the uart to default config
 * @co: Console handle
 * @options: Initial settings of uart
 *
 * Return: 0 on success, negative errno otherwise.
 */
static int __init cdns_uart_console_setup(struct console *co, char *options)
{
        struct uart_port *port = &cdns_uart_port[co->index];
        int baud = 9600;
        int bits = 8;
        int parity = 'n';
        int flow = 'n';

        if (co->index < 0 || co->index >= CDNS_UART_NR_PORTS)
                return -EINVAL;

        if (!port->membase) {
                pr_debug("console on " CDNS_UART_TTY_NAME "%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 cdns_uart_uart_driver;

static struct console cdns_uart_console = {
        .name   = CDNS_UART_TTY_NAME,
        .write  = cdns_uart_console_write,
        .device = uart_console_device,
        .setup  = cdns_uart_console_setup,
        .flags  = CON_PRINTBUFFER,
        .index  = -1, /* Specified on the cmdline (e.g. console=ttyPS ) */
        .data   = &cdns_uart_uart_driver,
};

/**
 * cdns_uart_console_init - Initialization call
 *
 * Return: 0 on success, negative errno otherwise
 */
static int __init cdns_uart_console_init(void)
{
        register_console(&cdns_uart_console);
        return 0;
}

console_initcall(cdns_uart_console_init);

#endif /* CONFIG_SERIAL_XILINX_PS_UART_CONSOLE */

static struct uart_driver cdns_uart_uart_driver = {
        .owner          = THIS_MODULE,
        .driver_name    = CDNS_UART_NAME,
        .dev_name       = CDNS_UART_TTY_NAME,
        .major          = CDNS_UART_MAJOR,
        .minor          = CDNS_UART_MINOR,
        .nr             = CDNS_UART_NR_PORTS,
#ifdef CONFIG_SERIAL_XILINX_PS_UART_CONSOLE
        .cons           = &cdns_uart_console,
#endif
};

#ifdef CONFIG_PM_SLEEP
/**
 * cdns_uart_suspend - suspend event
 * @device: Pointer to the device structure
 *
 * Return: 0
 */
static int cdns_uart_suspend(struct device *device)
{
        struct uart_port *port = dev_get_drvdata(device);
        struct tty_struct *tty;
        struct device *tty_dev;
        int may_wake = 0;

        /* Get the tty which could be NULL so don't assume it's valid */
        tty = tty_port_tty_get(&port->state->port);
        if (tty) {
                tty_dev = tty->dev;
                may_wake = device_may_wakeup(tty_dev);
                tty_kref_put(tty);
        }

        /*
         * Call the API provided in serial_core.c file which handles
         * the suspend.
         */
        uart_suspend_port(&cdns_uart_uart_driver, port);
        if (console_suspend_enabled && !may_wake) {
                struct cdns_uart *cdns_uart = port->private_data;

                clk_disable(cdns_uart->uartclk);
                clk_disable(cdns_uart->pclk);
        } else {
                unsigned long flags = 0;

                spin_lock_irqsave(&port->lock, flags);
                /* Empty the receive FIFO 1st before making changes */
                while (!(readl(port->membase + CDNS_UART_SR) &
                                        CDNS_UART_SR_RXEMPTY))
                        readl(port->membase + CDNS_UART_FIFO);
                /* set RX trigger level to 1 */
                writel(1, port->membase + CDNS_UART_RXWM);
                /* disable RX timeout interrups */
                writel(CDNS_UART_IXR_TOUT, port->membase + CDNS_UART_IDR);
                spin_unlock_irqrestore(&port->lock, flags);
        }

        return 0;
}

/**
 * cdns_uart_resume - Resume after a previous suspend
 * @device: Pointer to the device structure
 *
 * Return: 0
 */
static int cdns_uart_resume(struct device *device)
{
        struct uart_port *port = dev_get_drvdata(device);
        unsigned long flags = 0;
        u32 ctrl_reg;
        struct tty_struct *tty;
        struct device *tty_dev;
        int may_wake = 0;

        /* Get the tty which could be NULL so don't assume it's valid */
        tty = tty_port_tty_get(&port->state->port);
        if (tty) {
                tty_dev = tty->dev;
                may_wake = device_may_wakeup(tty_dev);
                tty_kref_put(tty);
        }

        if (console_suspend_enabled && !may_wake) {
                struct cdns_uart *cdns_uart = port->private_data;

                clk_enable(cdns_uart->pclk);
                clk_enable(cdns_uart->uartclk);

                spin_lock_irqsave(&port->lock, flags);

                /* Set TX/RX Reset */
                ctrl_reg = readl(port->membase + CDNS_UART_CR);
                ctrl_reg |= CDNS_UART_CR_TXRST | CDNS_UART_CR_RXRST;
                writel(ctrl_reg, port->membase + CDNS_UART_CR);
                while (readl(port->membase + CDNS_UART_CR) &
                                (CDNS_UART_CR_TXRST | CDNS_UART_CR_RXRST))
                        cpu_relax();

                /* restore rx timeout value */
                writel(rx_timeout, port->membase + CDNS_UART_RXTOUT);
                /* Enable Tx/Rx */
                ctrl_reg = readl(port->membase + CDNS_UART_CR);
                ctrl_reg &= ~(CDNS_UART_CR_TX_DIS | CDNS_UART_CR_RX_DIS);
                ctrl_reg |= CDNS_UART_CR_TX_EN | CDNS_UART_CR_RX_EN;
                writel(ctrl_reg, port->membase + CDNS_UART_CR);

                spin_unlock_irqrestore(&port->lock, flags);
        } else {
                spin_lock_irqsave(&port->lock, flags);
                /* restore original rx trigger level */
                writel(rx_trigger_level, port->membase + CDNS_UART_RXWM);
                /* enable RX timeout interrupt */
                writel(CDNS_UART_IXR_TOUT, port->membase + CDNS_UART_IER);
                spin_unlock_irqrestore(&port->lock, flags);
        }

        return uart_resume_port(&cdns_uart_uart_driver, port);
}
#endif /* ! CONFIG_PM_SLEEP */

static SIMPLE_DEV_PM_OPS(cdns_uart_dev_pm_ops, cdns_uart_suspend,
                cdns_uart_resume);

/**
 * cdns_uart_probe - Platform driver probe
 * @pdev: Pointer to the platform device structure
 *
 * Return: 0 on success, negative errno otherwise
 */
static int cdns_uart_probe(struct platform_device *pdev)
{
        int rc, id, irq;
        struct uart_port *port;
        struct resource *res;
        struct cdns_uart *cdns_uart_data;

        cdns_uart_data = devm_kzalloc(&pdev->dev, sizeof(*cdns_uart_data),
                        GFP_KERNEL);
        if (!cdns_uart_data)
                return -ENOMEM;

        cdns_uart_data->pclk = devm_clk_get(&pdev->dev, "pclk");
        if (IS_ERR(cdns_uart_data->pclk)) {
                cdns_uart_data->pclk = devm_clk_get(&pdev->dev, "aper_clk");
                if (!IS_ERR(cdns_uart_data->pclk))
                        dev_err(&pdev->dev, "clock name 'aper_clk' is deprecated.\n");
        }
        if (IS_ERR(cdns_uart_data->pclk)) {
                dev_err(&pdev->dev, "pclk clock not found.\n");
                return PTR_ERR(cdns_uart_data->pclk);
        }

        cdns_uart_data->uartclk = devm_clk_get(&pdev->dev, "uart_clk");
        if (IS_ERR(cdns_uart_data->uartclk)) {
                cdns_uart_data->uartclk = devm_clk_get(&pdev->dev, "ref_clk");
                if (!IS_ERR(cdns_uart_data->uartclk))
                        dev_err(&pdev->dev, "clock name 'ref_clk' is deprecated.\n");
        }
        if (IS_ERR(cdns_uart_data->uartclk)) {
                dev_err(&pdev->dev, "uart_clk clock not found.\n");
                return PTR_ERR(cdns_uart_data->uartclk);
        }

        rc = clk_prepare_enable(cdns_uart_data->pclk);
        if (rc) {
                dev_err(&pdev->dev, "Unable to enable pclk clock.\n");
                return rc;
        }
        rc = clk_prepare_enable(cdns_uart_data->uartclk);
        if (rc) {
                dev_err(&pdev->dev, "Unable to enable device clock.\n");
                goto err_out_clk_dis_pclk;
        }

        res = platform_get_resource(pdev, IORESOURCE_MEM, 0);
        if (!res) {
                rc = -ENODEV;
                goto err_out_clk_disable;
        }

        irq = platform_get_irq(pdev, 0);
        if (irq <= 0) {
                rc = -ENXIO;
                goto err_out_clk_disable;
        }

#ifdef CONFIG_COMMON_CLK
        cdns_uart_data->clk_rate_change_nb.notifier_call =
                        cdns_uart_clk_notifier_cb;
        if (clk_notifier_register(cdns_uart_data->uartclk,
                                &cdns_uart_data->clk_rate_change_nb))
                dev_warn(&pdev->dev, "Unable to register clock notifier.\n");
#endif
        /* Look for a serialN alias */
        id = of_alias_get_id(pdev->dev.of_node, "serial");
        if (id < 0)
                id = 0;

        /* Initialize the port structure */
        port = cdns_uart_get_port(id);

        if (!port) {
                dev_err(&pdev->dev, "Cannot get uart_port structure\n");
                rc = -ENODEV;
                goto err_out_notif_unreg;
        }

        /*
         * 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 = irq;
        port->dev = &pdev->dev;
        port->uartclk = clk_get_rate(cdns_uart_data->uartclk);
        port->private_data = cdns_uart_data;
        cdns_uart_data->port = port;
        platform_set_drvdata(pdev, port);

        rc = uart_add_one_port(&cdns_uart_uart_driver, port);
        if (rc) {
                dev_err(&pdev->dev,
                        "uart_add_one_port() failed; err=%i\n", rc);
                goto err_out_notif_unreg;
        }

        return 0;

err_out_notif_unreg:
#ifdef CONFIG_COMMON_CLK
        clk_notifier_unregister(cdns_uart_data->uartclk,
                        &cdns_uart_data->clk_rate_change_nb);
#endif
err_out_clk_disable:
        clk_disable_unprepare(cdns_uart_data->uartclk);
err_out_clk_dis_pclk:
        clk_disable_unprepare(cdns_uart_data->pclk);

        return rc;
}

/**
 * cdns_uart_remove - called when the platform driver is unregistered
 * @pdev: Pointer to the platform device structure
 *
 * Return: 0 on success, negative errno otherwise
 */
static int cdns_uart_remove(struct platform_device *pdev)
{
        struct uart_port *port = platform_get_drvdata(pdev);
        struct cdns_uart *cdns_uart_data = port->private_data;
        int rc;

        /* Remove the cdns_uart port from the serial core */
#ifdef CONFIG_COMMON_CLK
        clk_notifier_unregister(cdns_uart_data->uartclk,
                        &cdns_uart_data->clk_rate_change_nb);
#endif
        rc = uart_remove_one_port(&cdns_uart_uart_driver, port);
        port->mapbase = 0;
        clk_disable_unprepare(cdns_uart_data->uartclk);
        clk_disable_unprepare(cdns_uart_data->pclk);
        return rc;
}

/* Match table for of_platform binding */
static const struct of_device_id cdns_uart_of_match[] = {
        { .compatible = "xlnx,xuartps", },
        { .compatible = "cdns,uart-r1p8", },
        {}
};
MODULE_DEVICE_TABLE(of, cdns_uart_of_match);

static struct platform_driver cdns_uart_platform_driver = {
        .probe   = cdns_uart_probe,
        .remove  = cdns_uart_remove,
        .driver  = {
                .name = CDNS_UART_NAME,
                .of_match_table = cdns_uart_of_match,
                .pm = &cdns_uart_dev_pm_ops,
                },
};

static int __init cdns_uart_init(void)
{
        int retval = 0;

        /* Register the cdns_uart driver with the serial core */
        retval = uart_register_driver(&cdns_uart_uart_driver);
        if (retval)
                return retval;

        /* Register the platform driver */
        retval = platform_driver_register(&cdns_uart_platform_driver);
        if (retval)
                uart_unregister_driver(&cdns_uart_uart_driver);

        return retval;
}

static void __exit cdns_uart_exit(void)
{
        /* Unregister the platform driver */
        platform_driver_unregister(&cdns_uart_platform_driver);

        /* Unregister the cdns_uart driver */
        uart_unregister_driver(&cdns_uart_uart_driver);
}

module_init(cdns_uart_init);
module_exit(cdns_uart_exit);

MODULE_DESCRIPTION("Driver for Cadence UART");
MODULE_AUTHOR("Xilinx Inc.");
MODULE_LICENSE("GPL");