/*
 *  Driver for Atmel AT91 / AT32 Serial ports
 *  Copyright (C) 2003 Rick Bronson
 *
 *  Based on drivers/char/serial_sa1100.c, by Deep Blue Solutions Ltd.
 *  Based on drivers/char/serial.c, by Linus Torvalds, Theodore Ts'o.
 *
 *  DMA support added by Chip Coldwell.
 *
 * 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 program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 *
 */
#include <linux/module.h>
#include <linux/tty.h>
#include <linux/ioport.h>
#include <linux/slab.h>
#include <linux/init.h>
#include <linux/serial.h>
#include <linux/clk.h>
#include <linux/console.h>
#include <linux/sysrq.h>
#include <linux/tty_flip.h>
#include <linux/platform_device.h>
#include <linux/of.h>
#include <linux/of_device.h>
#include <linux/dma-mapping.h>
#include <linux/atmel_pdc.h>
#include <linux/atmel_serial.h>
#include <linux/uaccess.h>
#include <linux/pinctrl/consumer.h>
#include <linux/platform_data/atmel.h>

#include <asm/io.h>
#include <asm/ioctls.h>

#ifdef CONFIG_ARM
#include <mach/cpu.h>
#include <asm/gpio.h>
#endif

#define PDC_BUFFER_SIZE         512
/* Revisit: We should calculate this based on the actual port settings */
#define PDC_RX_TIMEOUT          (3 * 10)                /* 3 bytes */

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

#include <linux/serial_core.h>

static void atmel_start_rx(struct uart_port *port);
static void atmel_stop_rx(struct uart_port *port);

#ifdef CONFIG_SERIAL_ATMEL_TTYAT

/* Use device name ttyAT, major 204 and minor 154-169.  This is necessary if we
 * should coexist with the 8250 driver, such as if we have an external 16C550
 * UART. */
#define SERIAL_ATMEL_MAJOR      204
#define MINOR_START             154
#define ATMEL_DEVICENAME        "ttyAT"

#else

/* Use device name ttyS, major 4, minor 64-68.  This is the usual serial port
 * name, but it is legally reserved for the 8250 driver. */
#define SERIAL_ATMEL_MAJOR      TTY_MAJOR
#define MINOR_START             64
#define ATMEL_DEVICENAME        "ttyS"

#endif

#define ATMEL_ISR_PASS_LIMIT    256

/* UART registers. CR is write-only, hence no GET macro */
#define UART_PUT_CR(port,v)     __raw_writel(v, (port)->membase + ATMEL_US_CR)
#define UART_GET_MR(port)       __raw_readl((port)->membase + ATMEL_US_MR)
#define UART_PUT_MR(port,v)     __raw_writel(v, (port)->membase + ATMEL_US_MR)
#define UART_PUT_IER(port,v)    __raw_writel(v, (port)->membase + ATMEL_US_IER)
#define UART_PUT_IDR(port,v)    __raw_writel(v, (port)->membase + ATMEL_US_IDR)
#define UART_GET_IMR(port)      __raw_readl((port)->membase + ATMEL_US_IMR)
#define UART_GET_CSR(port)      __raw_readl((port)->membase + ATMEL_US_CSR)
#define UART_GET_CHAR(port)     __raw_readl((port)->membase + ATMEL_US_RHR)
#define UART_PUT_CHAR(port,v)   __raw_writel(v, (port)->membase + ATMEL_US_THR)
#define UART_GET_BRGR(port)     __raw_readl((port)->membase + ATMEL_US_BRGR)
#define UART_PUT_BRGR(port,v)   __raw_writel(v, (port)->membase + ATMEL_US_BRGR)
#define UART_PUT_RTOR(port,v)   __raw_writel(v, (port)->membase + ATMEL_US_RTOR)
#define UART_PUT_TTGR(port, v)  __raw_writel(v, (port)->membase + ATMEL_US_TTGR)

 /* PDC registers */
#define UART_PUT_PTCR(port,v)   __raw_writel(v, (port)->membase + ATMEL_PDC_PTCR)
#define UART_GET_PTSR(port)     __raw_readl((port)->membase + ATMEL_PDC_PTSR)

#define UART_PUT_RPR(port,v)    __raw_writel(v, (port)->membase + ATMEL_PDC_RPR)
#define UART_GET_RPR(port)      __raw_readl((port)->membase + ATMEL_PDC_RPR)
#define UART_PUT_RCR(port,v)    __raw_writel(v, (port)->membase + ATMEL_PDC_RCR)
#define UART_PUT_RNPR(port,v)   __raw_writel(v, (port)->membase + ATMEL_PDC_RNPR)
#define UART_PUT_RNCR(port,v)   __raw_writel(v, (port)->membase + ATMEL_PDC_RNCR)

#define UART_PUT_TPR(port,v)    __raw_writel(v, (port)->membase + ATMEL_PDC_TPR)
#define UART_PUT_TCR(port,v)    __raw_writel(v, (port)->membase + ATMEL_PDC_TCR)
#define UART_GET_TCR(port)      __raw_readl((port)->membase + ATMEL_PDC_TCR)

static int (*atmel_open_hook)(struct uart_port *);
static void (*atmel_close_hook)(struct uart_port *);

struct atmel_dma_buffer {
        unsigned char   *buf;
        dma_addr_t      dma_addr;
        unsigned int    dma_size;
        unsigned int    ofs;
};

struct atmel_uart_char {
        u16             status;
        u16             ch;
};

#define ATMEL_SERIAL_RINGSIZE 1024

/*
 * We wrap our port structure around the generic uart_port.
 */
struct atmel_uart_port {
        struct uart_port        uart;           /* uart */
        struct clk              *clk;           /* uart clock */
        int                     may_wakeup;     /* cached value of device_may_wakeup for times we need to disable it */
        u32                     backup_imr;     /* IMR saved during suspend */
        int                     break_active;   /* break being received */

        short                   use_dma_rx;     /* enable PDC receiver */
        short                   pdc_rx_idx;     /* current PDC RX buffer */
        struct atmel_dma_buffer pdc_rx[2];      /* PDC receier */

        short                   use_dma_tx;     /* enable PDC transmitter */
        struct atmel_dma_buffer pdc_tx;         /* PDC transmitter */

        struct tasklet_struct   tasklet;
        unsigned int            irq_status;
        unsigned int            irq_status_prev;

        struct circ_buf         rx_ring;

        struct serial_rs485     rs485;          /* rs485 settings */
        unsigned int            tx_done_mask;
};

static struct atmel_uart_port atmel_ports[ATMEL_MAX_UART];
static DECLARE_BITMAP(atmel_ports_in_use, ATMEL_MAX_UART);

#ifdef SUPPORT_SYSRQ
static struct console atmel_console;
#endif

#if defined(CONFIG_OF)
static const struct of_device_id atmel_serial_dt_ids[] = {
        { .compatible = "atmel,at91rm9200-usart" },
        { .compatible = "atmel,at91sam9260-usart" },
        { /* sentinel */ }
};

MODULE_DEVICE_TABLE(of, atmel_serial_dt_ids);
#endif

static inline struct atmel_uart_port *
to_atmel_uart_port(struct uart_port *uart)
{
        return container_of(uart, struct atmel_uart_port, uart);
}

#ifdef CONFIG_SERIAL_ATMEL_PDC
static bool atmel_use_dma_rx(struct uart_port *port)
{
        struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);

        return atmel_port->use_dma_rx;
}

static bool atmel_use_dma_tx(struct uart_port *port)
{
        struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);

        return atmel_port->use_dma_tx;
}
#else
static bool atmel_use_dma_rx(struct uart_port *port)
{
        return false;
}

static bool atmel_use_dma_tx(struct uart_port *port)
{
        return false;
}
#endif

/* Enable or disable the rs485 support */
void atmel_config_rs485(struct uart_port *port, struct serial_rs485 *rs485conf)
{
        struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
        unsigned int mode;
        unsigned long flags;

        spin_lock_irqsave(&port->lock, flags);

        /* Disable interrupts */
        UART_PUT_IDR(port, atmel_port->tx_done_mask);

        mode = UART_GET_MR(port);

        /* Resetting serial mode to RS232 (0x0) */
        mode &= ~ATMEL_US_USMODE;

        atmel_port->rs485 = *rs485conf;

        if (rs485conf->flags & SER_RS485_ENABLED) {
                dev_dbg(port->dev, "Setting UART to RS485\n");
                atmel_port->tx_done_mask = ATMEL_US_TXEMPTY;
                if ((rs485conf->delay_rts_after_send) > 0)
                        UART_PUT_TTGR(port, rs485conf->delay_rts_after_send);
                mode |= ATMEL_US_USMODE_RS485;
        } else {
                dev_dbg(port->dev, "Setting UART to RS232\n");
                if (atmel_use_dma_tx(port))
                        atmel_port->tx_done_mask = ATMEL_US_ENDTX |
                                ATMEL_US_TXBUFE;
                else
                        atmel_port->tx_done_mask = ATMEL_US_TXRDY;
        }
        UART_PUT_MR(port, mode);

        /* Enable interrupts */
        UART_PUT_IER(port, atmel_port->tx_done_mask);

        spin_unlock_irqrestore(&port->lock, flags);

}

/*
 * Return TIOCSER_TEMT when transmitter FIFO and Shift register is empty.
 */
static u_int atmel_tx_empty(struct uart_port *port)
{
        return (UART_GET_CSR(port) & ATMEL_US_TXEMPTY) ? TIOCSER_TEMT : 0;
}

/*
 * Set state of the modem control output lines
 */
static void atmel_set_mctrl(struct uart_port *port, u_int mctrl)
{
        unsigned int control = 0;
        unsigned int mode;
        struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);

#ifdef CONFIG_ARCH_AT91RM9200
        if (cpu_is_at91rm9200()) {
                /*
                 * AT91RM9200 Errata #39: RTS0 is not internally connected
                 * to PA21. We need to drive the pin manually.
                 */
                if (port->mapbase == AT91RM9200_BASE_US0) {
                        if (mctrl & TIOCM_RTS)
                                at91_set_gpio_value(AT91_PIN_PA21, 0);
                        else
                                at91_set_gpio_value(AT91_PIN_PA21, 1);
                }
        }
#endif

        if (mctrl & TIOCM_RTS)
                control |= ATMEL_US_RTSEN;
        else
                control |= ATMEL_US_RTSDIS;

        if (mctrl & TIOCM_DTR)
                control |= ATMEL_US_DTREN;
        else
                control |= ATMEL_US_DTRDIS;

        UART_PUT_CR(port, control);

        /* Local loopback mode? */
        mode = UART_GET_MR(port) & ~ATMEL_US_CHMODE;
        if (mctrl & TIOCM_LOOP)
                mode |= ATMEL_US_CHMODE_LOC_LOOP;
        else
                mode |= ATMEL_US_CHMODE_NORMAL;

        /* Resetting serial mode to RS232 (0x0) */
        mode &= ~ATMEL_US_USMODE;

        if (atmel_port->rs485.flags & SER_RS485_ENABLED) {
                dev_dbg(port->dev, "Setting UART to RS485\n");
                if ((atmel_port->rs485.delay_rts_after_send) > 0)
                        UART_PUT_TTGR(port,
                                        atmel_port->rs485.delay_rts_after_send);
                mode |= ATMEL_US_USMODE_RS485;
        } else {
                dev_dbg(port->dev, "Setting UART to RS232\n");
        }
        UART_PUT_MR(port, mode);
}

/*
 * Get state of the modem control input lines
 */
static u_int atmel_get_mctrl(struct uart_port *port)
{
        unsigned int status, ret = 0;

        status = UART_GET_CSR(port);

        /*
         * The control signals are active low.
         */
        if (!(status & ATMEL_US_DCD))
                ret |= TIOCM_CD;
        if (!(status & ATMEL_US_CTS))
                ret |= TIOCM_CTS;
        if (!(status & ATMEL_US_DSR))
                ret |= TIOCM_DSR;
        if (!(status & ATMEL_US_RI))
                ret |= TIOCM_RI;

        return ret;
}

/*
 * Stop transmitting.
 */
static void atmel_stop_tx(struct uart_port *port)
{
        struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);

        if (atmel_use_dma_tx(port)) {
                /* disable PDC transmit */
                UART_PUT_PTCR(port, ATMEL_PDC_TXTDIS);
        }
        /* Disable interrupts */
        UART_PUT_IDR(port, atmel_port->tx_done_mask);

        if ((atmel_port->rs485.flags & SER_RS485_ENABLED) &&
            !(atmel_port->rs485.flags & SER_RS485_RX_DURING_TX))
                atmel_start_rx(port);
}

/*
 * Start transmitting.
 */
static void atmel_start_tx(struct uart_port *port)
{
        struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);

        if (atmel_use_dma_tx(port)) {
                if (UART_GET_PTSR(port) & ATMEL_PDC_TXTEN)
                        /* The transmitter is already running.  Yes, we
                           really need this.*/
                        return;

                if ((atmel_port->rs485.flags & SER_RS485_ENABLED) &&
                    !(atmel_port->rs485.flags & SER_RS485_RX_DURING_TX))
                        atmel_stop_rx(port);

                /* re-enable PDC transmit */
                UART_PUT_PTCR(port, ATMEL_PDC_TXTEN);
        }
        /* Enable interrupts */
        UART_PUT_IER(port, atmel_port->tx_done_mask);
}

/*
 * start receiving - port is in process of being opened.
 */
static void atmel_start_rx(struct uart_port *port)
{
        UART_PUT_CR(port, ATMEL_US_RSTSTA);  /* reset status and receiver */

        UART_PUT_CR(port, ATMEL_US_RXEN);

        if (atmel_use_dma_rx(port)) {
                /* enable PDC controller */
                UART_PUT_IER(port, ATMEL_US_ENDRX | ATMEL_US_TIMEOUT |
                        port->read_status_mask);
                UART_PUT_PTCR(port, ATMEL_PDC_RXTEN);
        } else {
                UART_PUT_IER(port, ATMEL_US_RXRDY);
        }
}

/*
 * Stop receiving - port is in process of being closed.
 */
static void atmel_stop_rx(struct uart_port *port)
{
        UART_PUT_CR(port, ATMEL_US_RXDIS);

        if (atmel_use_dma_rx(port)) {
                /* disable PDC receive */
                UART_PUT_PTCR(port, ATMEL_PDC_RXTDIS);
                UART_PUT_IDR(port, ATMEL_US_ENDRX | ATMEL_US_TIMEOUT |
                        port->read_status_mask);
        } else {
                UART_PUT_IDR(port, ATMEL_US_RXRDY);
        }
}

/*
 * Enable modem status interrupts
 */
static void atmel_enable_ms(struct uart_port *port)
{
        UART_PUT_IER(port, ATMEL_US_RIIC | ATMEL_US_DSRIC
                        | ATMEL_US_DCDIC | ATMEL_US_CTSIC);
}

/*
 * Control the transmission of a break signal
 */
static void atmel_break_ctl(struct uart_port *port, int break_state)
{
        if (break_state != 0)
                UART_PUT_CR(port, ATMEL_US_STTBRK);     /* start break */
        else
                UART_PUT_CR(port, ATMEL_US_STPBRK);     /* stop break */
}

/*
 * Stores the incoming character in the ring buffer
 */
static void
atmel_buffer_rx_char(struct uart_port *port, unsigned int status,
                     unsigned int ch)
{
        struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
        struct circ_buf *ring = &atmel_port->rx_ring;
        struct atmel_uart_char *c;

        if (!CIRC_SPACE(ring->head, ring->tail, ATMEL_SERIAL_RINGSIZE))
                /* Buffer overflow, ignore char */
                return;

        c = &((struct atmel_uart_char *)ring->buf)[ring->head];
        c->status       = status;
        c->ch           = ch;

        /* Make sure the character is stored before we update head. */
        smp_wmb();

        ring->head = (ring->head + 1) & (ATMEL_SERIAL_RINGSIZE - 1);
}

/*
 * Deal with parity, framing and overrun errors.
 */
static void atmel_pdc_rxerr(struct uart_port *port, unsigned int status)
{
        /* clear error */
        UART_PUT_CR(port, ATMEL_US_RSTSTA);

        if (status & ATMEL_US_RXBRK) {
                /* ignore side-effect */
                status &= ~(ATMEL_US_PARE | ATMEL_US_FRAME);
                port->icount.brk++;
        }
        if (status & ATMEL_US_PARE)
                port->icount.parity++;
        if (status & ATMEL_US_FRAME)
                port->icount.frame++;
        if (status & ATMEL_US_OVRE)
                port->icount.overrun++;
}

/*
 * Characters received (called from interrupt handler)
 */
static void atmel_rx_chars(struct uart_port *port)
{
        struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
        unsigned int status, ch;

        status = UART_GET_CSR(port);
        while (status & ATMEL_US_RXRDY) {
                ch = UART_GET_CHAR(port);

                /*
                 * note that the error handling code is
                 * out of the main execution path
                 */
                if (unlikely(status & (ATMEL_US_PARE | ATMEL_US_FRAME
                                       | ATMEL_US_OVRE | ATMEL_US_RXBRK)
                             || atmel_port->break_active)) {

                        /* clear error */
                        UART_PUT_CR(port, ATMEL_US_RSTSTA);

                        if (status & ATMEL_US_RXBRK
                            && !atmel_port->break_active) {
                                atmel_port->break_active = 1;
                                UART_PUT_IER(port, ATMEL_US_RXBRK);
                        } else {
                                /*
                                 * This is either the end-of-break
                                 * condition or we've received at
                                 * least one character without RXBRK
                                 * being set. In both cases, the next
                                 * RXBRK will indicate start-of-break.
                                 */
                                UART_PUT_IDR(port, ATMEL_US_RXBRK);
                                status &= ~ATMEL_US_RXBRK;
                                atmel_port->break_active = 0;
                        }
                }

                atmel_buffer_rx_char(port, status, ch);
                status = UART_GET_CSR(port);
        }

        tasklet_schedule(&atmel_port->tasklet);
}

/*
 * Transmit characters (called from tasklet with TXRDY interrupt
 * disabled)
 */
static void atmel_tx_chars(struct uart_port *port)
{
        struct circ_buf *xmit = &port->state->xmit;
        struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);

        if (port->x_char && UART_GET_CSR(port) & atmel_port->tx_done_mask) {
                UART_PUT_CHAR(port, port->x_char);
                port->icount.tx++;
                port->x_char = 0;
        }
        if (uart_circ_empty(xmit) || uart_tx_stopped(port))
                return;

        while (UART_GET_CSR(port) & atmel_port->tx_done_mask) {
                UART_PUT_CHAR(port, xmit->buf[xmit->tail]);
                xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
                port->icount.tx++;
                if (uart_circ_empty(xmit))
                        break;
        }

        if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
                uart_write_wakeup(port);

        if (!uart_circ_empty(xmit))
                /* Enable interrupts */
                UART_PUT_IER(port, atmel_port->tx_done_mask);
}

/*
 * receive interrupt handler.
 */
static void
atmel_handle_receive(struct uart_port *port, unsigned int pending)
{
        struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);

        if (atmel_use_dma_rx(port)) {
                /*
                 * PDC receive. Just schedule the tasklet and let it
                 * figure out the details.
                 *
                 * TODO: We're not handling error flags correctly at
                 * the moment.
                 */
                if (pending & (ATMEL_US_ENDRX | ATMEL_US_TIMEOUT)) {
                        UART_PUT_IDR(port, (ATMEL_US_ENDRX
                                                | ATMEL_US_TIMEOUT));
                        tasklet_schedule(&atmel_port->tasklet);
                }

                if (pending & (ATMEL_US_RXBRK | ATMEL_US_OVRE |
                                ATMEL_US_FRAME | ATMEL_US_PARE))
                        atmel_pdc_rxerr(port, pending);
        }

        /* Interrupt receive */
        if (pending & ATMEL_US_RXRDY)
                atmel_rx_chars(port);
        else if (pending & ATMEL_US_RXBRK) {
                /*
                 * End of break detected. If it came along with a
                 * character, atmel_rx_chars will handle it.
                 */
                UART_PUT_CR(port, ATMEL_US_RSTSTA);
                UART_PUT_IDR(port, ATMEL_US_RXBRK);
                atmel_port->break_active = 0;
        }
}

/*
 * transmit interrupt handler. (Transmit is IRQF_NODELAY safe)
 */
static void
atmel_handle_transmit(struct uart_port *port, unsigned int pending)
{
        struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);

        if (pending & atmel_port->tx_done_mask) {
                /* Either PDC or interrupt transmission */
                UART_PUT_IDR(port, atmel_port->tx_done_mask);
                tasklet_schedule(&atmel_port->tasklet);
        }
}

/*
 * status flags interrupt handler.
 */
static void
atmel_handle_status(struct uart_port *port, unsigned int pending,
                    unsigned int status)
{
        struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);

        if (pending & (ATMEL_US_RIIC | ATMEL_US_DSRIC | ATMEL_US_DCDIC
                                | ATMEL_US_CTSIC)) {
                atmel_port->irq_status = status;
                tasklet_schedule(&atmel_port->tasklet);
        }
}

/*
 * Interrupt handler
 */
static irqreturn_t atmel_interrupt(int irq, void *dev_id)
{
        struct uart_port *port = dev_id;
        unsigned int status, pending, pass_counter = 0;

        do {
                status = UART_GET_CSR(port);
                pending = status & UART_GET_IMR(port);
                if (!pending)
                        break;

                atmel_handle_receive(port, pending);
                atmel_handle_status(port, pending, status);
                atmel_handle_transmit(port, pending);
        } while (pass_counter++ < ATMEL_ISR_PASS_LIMIT);

        return pass_counter ? IRQ_HANDLED : IRQ_NONE;
}

/*
 * Called from tasklet with ENDTX and TXBUFE interrupts disabled.
 */
static void atmel_tx_dma(struct uart_port *port)
{
        struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
        struct circ_buf *xmit = &port->state->xmit;
        struct atmel_dma_buffer *pdc = &atmel_port->pdc_tx;
        int count;

        /* nothing left to transmit? */
        if (UART_GET_TCR(port))
                return;

        xmit->tail += pdc->ofs;
        xmit->tail &= UART_XMIT_SIZE - 1;

        port->icount.tx += pdc->ofs;
        pdc->ofs = 0;

        /* more to transmit - setup next transfer */

        /* disable PDC transmit */
        UART_PUT_PTCR(port, ATMEL_PDC_TXTDIS);

        if (!uart_circ_empty(xmit) && !uart_tx_stopped(port)) {
                dma_sync_single_for_device(port->dev,
                                           pdc->dma_addr,
                                           pdc->dma_size,
                                           DMA_TO_DEVICE);

                count = CIRC_CNT_TO_END(xmit->head, xmit->tail, UART_XMIT_SIZE);
                pdc->ofs = count;

                UART_PUT_TPR(port, pdc->dma_addr + xmit->tail);
                UART_PUT_TCR(port, count);
                /* re-enable PDC transmit */
                UART_PUT_PTCR(port, ATMEL_PDC_TXTEN);
                /* Enable interrupts */
                UART_PUT_IER(port, atmel_port->tx_done_mask);
        } else {
                if ((atmel_port->rs485.flags & SER_RS485_ENABLED) &&
                    !(atmel_port->rs485.flags & SER_RS485_RX_DURING_TX)) {
                        /* DMA done, stop TX, start RX for RS485 */
                        atmel_start_rx(port);
                }
        }

        if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
                uart_write_wakeup(port);
}

static void atmel_rx_from_ring(struct uart_port *port)
{
        struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
        struct circ_buf *ring = &atmel_port->rx_ring;
        unsigned int flg;
        unsigned int status;

        while (ring->head != ring->tail) {
                struct atmel_uart_char c;

                /* Make sure c is loaded after head. */
                smp_rmb();

                c = ((struct atmel_uart_char *)ring->buf)[ring->tail];

                ring->tail = (ring->tail + 1) & (ATMEL_SERIAL_RINGSIZE - 1);

                port->icount.rx++;
                status = c.status;
                flg = TTY_NORMAL;

                /*
                 * note that the error handling code is
                 * out of the main execution path
                 */
                if (unlikely(status & (ATMEL_US_PARE | ATMEL_US_FRAME
                                       | ATMEL_US_OVRE | ATMEL_US_RXBRK))) {
                        if (status & ATMEL_US_RXBRK) {
                                /* ignore side-effect */
                                status &= ~(ATMEL_US_PARE | ATMEL_US_FRAME);

                                port->icount.brk++;
                                if (uart_handle_break(port))
                                        continue;
                        }
                        if (status & ATMEL_US_PARE)
                                port->icount.parity++;
                        if (status & ATMEL_US_FRAME)
                                port->icount.frame++;
                        if (status & ATMEL_US_OVRE)
                                port->icount.overrun++;

                        status &= port->read_status_mask;

                        if (status & ATMEL_US_RXBRK)
                                flg = TTY_BREAK;
                        else if (status & ATMEL_US_PARE)
                                flg = TTY_PARITY;
                        else if (status & ATMEL_US_FRAME)
                                flg = TTY_FRAME;
                }


                if (uart_handle_sysrq_char(port, c.ch))
                        continue;

                uart_insert_char(port, status, ATMEL_US_OVRE, c.ch, flg);
        }

        /*
         * Drop the lock here since it might end up calling
         * uart_start(), which takes the lock.
         */
        spin_unlock(&port->lock);
        tty_flip_buffer_push(&port->state->port);
        spin_lock(&port->lock);
}

static void atmel_rx_from_dma(struct uart_port *port)
{
        struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
        struct tty_port *tport = &port->state->port;
        struct atmel_dma_buffer *pdc;
        int rx_idx = atmel_port->pdc_rx_idx;
        unsigned int head;
        unsigned int tail;
        unsigned int count;

        do {
                /* Reset the UART timeout early so that we don't miss one */
                UART_PUT_CR(port, ATMEL_US_STTTO);

                pdc = &atmel_port->pdc_rx[rx_idx];
                head = UART_GET_RPR(port) - pdc->dma_addr;
                tail = pdc->ofs;

                /* If the PDC has switched buffers, RPR won't contain
                 * any address within the current buffer. Since head
                 * is unsigned, we just need a one-way comparison to
                 * find out.
                 *
                 * In this case, we just need to consume the entire
                 * buffer and resubmit it for DMA. This will clear the
                 * ENDRX bit as well, so that we can safely re-enable
                 * all interrupts below.
                 */
                head = min(head, pdc->dma_size);

                if (likely(head != tail)) {
                        dma_sync_single_for_cpu(port->dev, pdc->dma_addr,
                                        pdc->dma_size, DMA_FROM_DEVICE);

                        /*
                         * head will only wrap around when we recycle
                         * the DMA buffer, and when that happens, we
                         * explicitly set tail to 0. So head will
                         * always be greater than tail.
                         */
                        count = head - tail;

                        tty_insert_flip_string(tport, pdc->buf + pdc->ofs,
                                                count);

                        dma_sync_single_for_device(port->dev, pdc->dma_addr,
                                        pdc->dma_size, DMA_FROM_DEVICE);

                        port->icount.rx += count;
                        pdc->ofs = head;
                }

                /*
                 * If the current buffer is full, we need to check if
                 * the next one contains any additional data.
                 */
                if (head >= pdc->dma_size) {
                        pdc->ofs = 0;
                        UART_PUT_RNPR(port, pdc->dma_addr);
                        UART_PUT_RNCR(port, pdc->dma_size);

                        rx_idx = !rx_idx;
                        atmel_port->pdc_rx_idx = rx_idx;
                }
        } while (head >= pdc->dma_size);

        /*
         * Drop the lock here since it might end up calling
         * uart_start(), which takes the lock.
         */
        spin_unlock(&port->lock);
        tty_flip_buffer_push(tport);
        spin_lock(&port->lock);

        UART_PUT_IER(port, ATMEL_US_ENDRX | ATMEL_US_TIMEOUT);
}

/*
 * tasklet handling tty stuff outside the interrupt handler.
 */
static void atmel_tasklet_func(unsigned long data)
{
        struct uart_port *port = (struct uart_port *)data;
        struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
        unsigned int status;
        unsigned int status_change;

        /* The interrupt handler does not take the lock */
        spin_lock(&port->lock);

        if (atmel_use_dma_tx(port))
                atmel_tx_dma(port);
        else
                atmel_tx_chars(port);

        status = atmel_port->irq_status;
        status_change = status ^ atmel_port->irq_status_prev;

        if (status_change & (ATMEL_US_RI | ATMEL_US_DSR
                                | ATMEL_US_DCD | ATMEL_US_CTS)) {
                /* TODO: All reads to CSR will clear these interrupts! */
                if (status_change & ATMEL_US_RI)
                        port->icount.rng++;
                if (status_change & ATMEL_US_DSR)
                        port->icount.dsr++;
                if (status_change & ATMEL_US_DCD)
                        uart_handle_dcd_change(port, !(status & ATMEL_US_DCD));
                if (status_change & ATMEL_US_CTS)
                        uart_handle_cts_change(port, !(status & ATMEL_US_CTS));

                wake_up_interruptible(&port->state->port.delta_msr_wait);

                atmel_port->irq_status_prev = status;
        }

        if (atmel_use_dma_rx(port))
                atmel_rx_from_dma(port);
        else
                atmel_rx_from_ring(port);

        spin_unlock(&port->lock);
}

/*
 * Perform initialization and enable port for reception
 */
static int atmel_startup(struct uart_port *port)
{
        struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
        struct tty_struct *tty = port->state->port.tty;
        int retval;

        /*
         * Ensure that no interrupts are enabled otherwise when
         * request_irq() is called we could get stuck trying to
         * handle an unexpected interrupt
         */
        UART_PUT_IDR(port, -1);

        /*
         * Allocate the IRQ
         */
        retval = request_irq(port->irq, atmel_interrupt, IRQF_SHARED,
                        tty ? tty->name : "atmel_serial", port);
        if (retval) {
                printk("atmel_serial: atmel_startup - Can't get irq\n");
                return retval;
        }

        /*
         * Initialize DMA (if necessary)
         */
        if (atmel_use_dma_rx(port)) {
                int i;

                for (i = 0; i < 2; i++) {
                        struct atmel_dma_buffer *pdc = &atmel_port->pdc_rx[i];

                        pdc->buf = kmalloc(PDC_BUFFER_SIZE, GFP_KERNEL);
                        if (pdc->buf == NULL) {
                                if (i != 0) {
                                        dma_unmap_single(port->dev,
                                                atmel_port->pdc_rx[0].dma_addr,
                                                PDC_BUFFER_SIZE,
                                                DMA_FROM_DEVICE);
                                        kfree(atmel_port->pdc_rx[0].buf);
                                }
                                free_irq(port->irq, port);
                                return -ENOMEM;
                        }
                        pdc->dma_addr = dma_map_single(port->dev,
                                                       pdc->buf,
                                                       PDC_BUFFER_SIZE,
                                                       DMA_FROM_DEVICE);
                        pdc->dma_size = PDC_BUFFER_SIZE;
                        pdc->ofs = 0;
                }

                atmel_port->pdc_rx_idx = 0;

                UART_PUT_RPR(port, atmel_port->pdc_rx[0].dma_addr);
                UART_PUT_RCR(port, PDC_BUFFER_SIZE);

                UART_PUT_RNPR(port, atmel_port->pdc_rx[1].dma_addr);
                UART_PUT_RNCR(port, PDC_BUFFER_SIZE);
        }
        if (atmel_use_dma_tx(port)) {
                struct atmel_dma_buffer *pdc = &atmel_port->pdc_tx;
                struct circ_buf *xmit = &port->state->xmit;

                pdc->buf = xmit->buf;
                pdc->dma_addr = dma_map_single(port->dev,
                                               pdc->buf,
                                               UART_XMIT_SIZE,
                                               DMA_TO_DEVICE);
                pdc->dma_size = UART_XMIT_SIZE;
                pdc->ofs = 0;
        }

        /*
         * If there is a specific "open" function (to register
         * control line interrupts)
         */
        if (atmel_open_hook) {
                retval = atmel_open_hook(port);
                if (retval) {
                        free_irq(port->irq, port);
                        return retval;
                }
        }

        /* Save current CSR for comparison in atmel_tasklet_func() */
        atmel_port->irq_status_prev = UART_GET_CSR(port);
        atmel_port->irq_status = atmel_port->irq_status_prev;

        /*
         * Finally, enable the serial port
         */
        UART_PUT_CR(port, ATMEL_US_RSTSTA | ATMEL_US_RSTRX);
        /* enable xmit & rcvr */

        UART_PUT_CR(port, ATMEL_US_TXEN | ATMEL_US_RXEN);

        if (atmel_use_dma_rx(port)) {
                /* set UART timeout */
                UART_PUT_RTOR(port, PDC_RX_TIMEOUT);
                UART_PUT_CR(port, ATMEL_US_STTTO);

                UART_PUT_IER(port, ATMEL_US_ENDRX | ATMEL_US_TIMEOUT);
                /* enable PDC controller */
                UART_PUT_PTCR(port, ATMEL_PDC_RXTEN);
        } else {
                /* enable receive only */
                UART_PUT_IER(port, ATMEL_US_RXRDY);
        }

        return 0;
}

/*
 * Disable the port
 */
static void atmel_shutdown(struct uart_port *port)
{
        struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
        /*
         * Ensure everything is stopped.
         */
        atmel_stop_rx(port);
        atmel_stop_tx(port);

        /*
         * Shut-down the DMA.
         */
        if (atmel_use_dma_rx(port)) {
                int i;

                for (i = 0; i < 2; i++) {
                        struct atmel_dma_buffer *pdc = &atmel_port->pdc_rx[i];

                        dma_unmap_single(port->dev,
                                         pdc->dma_addr,
                                         pdc->dma_size,
                                         DMA_FROM_DEVICE);
                        kfree(pdc->buf);
                }
        }
        if (atmel_use_dma_tx(port)) {
                struct atmel_dma_buffer *pdc = &atmel_port->pdc_tx;

                dma_unmap_single(port->dev,
                                 pdc->dma_addr,
                                 pdc->dma_size,
                                 DMA_TO_DEVICE);
        }

        /*
         * Disable all interrupts, port and break condition.
         */
        UART_PUT_CR(port, ATMEL_US_RSTSTA);
        UART_PUT_IDR(port, -1);

        /*
         * Free the interrupt
         */
        free_irq(port->irq, port);

        /*
         * If there is a specific "close" function (to unregister
         * control line interrupts)
         */
        if (atmel_close_hook)
                atmel_close_hook(port);
}

/*
 * Flush any TX data submitted for DMA. Called when the TX circular
 * buffer is reset.
 */
static void atmel_flush_buffer(struct uart_port *port)
{
        struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);

        if (atmel_use_dma_tx(port)) {
                UART_PUT_TCR(port, 0);
                atmel_port->pdc_tx.ofs = 0;
        }
}

/*
 * Power / Clock management.
 */
static void atmel_serial_pm(struct uart_port *port, unsigned int state,
                            unsigned int oldstate)
{
        struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);

        switch (state) {
        case 0:
                /*
                 * Enable the peripheral clock for this serial port.
                 * This is called on uart_open() or a resume event.
                 */
                clk_prepare_enable(atmel_port->clk);

                /* re-enable interrupts if we disabled some on suspend */
                UART_PUT_IER(port, atmel_port->backup_imr);
                break;
        case 3:
                /* Back up the interrupt mask and disable all interrupts */
                atmel_port->backup_imr = UART_GET_IMR(port);
                UART_PUT_IDR(port, -1);

                /*
                 * Disable the peripheral clock for this serial port.
                 * This is called on uart_close() or a suspend event.
                 */
                clk_disable_unprepare(atmel_port->clk);
                break;
        default:
                printk(KERN_ERR "atmel_serial: unknown pm %d\n", state);
        }
}

/*
 * Change the port parameters
 */
static void atmel_set_termios(struct uart_port *port, struct ktermios *termios,
                              struct ktermios *old)
{
        unsigned long flags;
        unsigned int mode, imr, quot, baud;
        struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);

        /* Get current mode register */
        mode = UART_GET_MR(port) & ~(ATMEL_US_USCLKS | ATMEL_US_CHRL
                                        | ATMEL_US_NBSTOP | ATMEL_US_PAR
                                        | ATMEL_US_USMODE);

        baud = uart_get_baud_rate(port, termios, old, 0, port->uartclk / 16);
        quot = uart_get_divisor(port, baud);

        if (quot > 65535) {     /* BRGR is 16-bit, so switch to slower clock */
                quot /= 8;
                mode |= ATMEL_US_USCLKS_MCK_DIV8;
        }

        /* byte size */
        switch (termios->c_cflag & CSIZE) {
        case CS5:
                mode |= ATMEL_US_CHRL_5;
                break;
        case CS6:
                mode |= ATMEL_US_CHRL_6;
                break;
        case CS7:
                mode |= ATMEL_US_CHRL_7;
                break;
        default:
                mode |= ATMEL_US_CHRL_8;
                break;
        }

        /* stop bits */
        if (termios->c_cflag & CSTOPB)
                mode |= ATMEL_US_NBSTOP_2;

        /* parity */
        if (termios->c_cflag & PARENB) {
                /* Mark or Space parity */
                if (termios->c_cflag & CMSPAR) {
                        if (termios->c_cflag & PARODD)
                                mode |= ATMEL_US_PAR_MARK;
                        else
                                mode |= ATMEL_US_PAR_SPACE;
                } else if (termios->c_cflag & PARODD)
                        mode |= ATMEL_US_PAR_ODD;
                else
                        mode |= ATMEL_US_PAR_EVEN;
        } else
                mode |= ATMEL_US_PAR_NONE;

        /* hardware handshake (RTS/CTS) */
        if (termios->c_cflag & CRTSCTS)
                mode |= ATMEL_US_USMODE_HWHS;
        else
                mode |= ATMEL_US_USMODE_NORMAL;

        spin_lock_irqsave(&port->lock, flags);

        port->read_status_mask = ATMEL_US_OVRE;
        if (termios->c_iflag & INPCK)
                port->read_status_mask |= (ATMEL_US_FRAME | ATMEL_US_PARE);
        if (termios->c_iflag & (BRKINT | PARMRK))
                port->read_status_mask |= ATMEL_US_RXBRK;

        if (atmel_use_dma_rx(port))
                /* need to enable error interrupts */
                UART_PUT_IER(port, port->read_status_mask);

        /*
         * Characters to ignore
         */
        port->ignore_status_mask = 0;
        if (termios->c_iflag & IGNPAR)
                port->ignore_status_mask |= (ATMEL_US_FRAME | ATMEL_US_PARE);
        if (termios->c_iflag & IGNBRK) {
                port->ignore_status_mask |= ATMEL_US_RXBRK;
                /*
                 * If we're ignoring parity and break indicators,
                 * ignore overruns too (for real raw support).
                 */
                if (termios->c_iflag & IGNPAR)
                        port->ignore_status_mask |= ATMEL_US_OVRE;
        }
        /* TODO: Ignore all characters if CREAD is set.*/

        /* update the per-port timeout */
        uart_update_timeout(port, termios->c_cflag, baud);

        /*
         * save/disable interrupts. The tty layer will ensure that the
         * transmitter is empty if requested by the caller, so there's
         * no need to wait for it here.
         */
        imr = UART_GET_IMR(port);
        UART_PUT_IDR(port, -1);

        /* disable receiver and transmitter */
        UART_PUT_CR(port, ATMEL_US_TXDIS | ATMEL_US_RXDIS);

        /* Resetting serial mode to RS232 (0x0) */
        mode &= ~ATMEL_US_USMODE;

        if (atmel_port->rs485.flags & SER_RS485_ENABLED) {
                dev_dbg(port->dev, "Setting UART to RS485\n");
                if ((atmel_port->rs485.delay_rts_after_send) > 0)
                        UART_PUT_TTGR(port,
                                        atmel_port->rs485.delay_rts_after_send);
                mode |= ATMEL_US_USMODE_RS485;
        } else {
                dev_dbg(port->dev, "Setting UART to RS232\n");
        }

        /* set the parity, stop bits and data size */
        UART_PUT_MR(port, mode);

        /* set the baud rate */
        UART_PUT_BRGR(port, quot);
        UART_PUT_CR(port, ATMEL_US_RSTSTA | ATMEL_US_RSTRX);
        UART_PUT_CR(port, ATMEL_US_TXEN | ATMEL_US_RXEN);

        /* restore interrupts */
        UART_PUT_IER(port, imr);

        /* CTS flow-control and modem-status interrupts */
        if (UART_ENABLE_MS(port, termios->c_cflag))
                port->ops->enable_ms(port);

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

static void atmel_set_ldisc(struct uart_port *port, int new)
{
        if (new == N_PPS) {
                port->flags |= UPF_HARDPPS_CD;
                atmel_enable_ms(port);
        } else {
                port->flags &= ~UPF_HARDPPS_CD;
        }
}

/*
 * Return string describing the specified port
 */
static const char *atmel_type(struct uart_port *port)
{
        return (port->type == PORT_ATMEL) ? "ATMEL_SERIAL" : NULL;
}

/*
 * Release the memory region(s) being used by 'port'.
 */
static void atmel_release_port(struct uart_port *port)
{
        struct platform_device *pdev = to_platform_device(port->dev);
        int size = pdev->resource[0].end - pdev->resource[0].start + 1;

        release_mem_region(port->mapbase, size);

        if (port->flags & UPF_IOREMAP) {
                iounmap(port->membase);
                port->membase = NULL;
        }
}

/*
 * Request the memory region(s) being used by 'port'.
 */
static int atmel_request_port(struct uart_port *port)
{
        struct platform_device *pdev = to_platform_device(port->dev);
        int size = pdev->resource[0].end - pdev->resource[0].start + 1;

        if (!request_mem_region(port->mapbase, size, "atmel_serial"))
                return -EBUSY;

        if (port->flags & UPF_IOREMAP) {
                port->membase = ioremap(port->mapbase, size);
                if (port->membase == NULL) {
                        release_mem_region(port->mapbase, size);
                        return -ENOMEM;
                }
        }

        return 0;
}

/*
 * Configure/autoconfigure the port.
 */
static void atmel_config_port(struct uart_port *port, int flags)
{
        if (flags & UART_CONFIG_TYPE) {
                port->type = PORT_ATMEL;
                atmel_request_port(port);
        }
}

/*
 * Verify the new serial_struct (for TIOCSSERIAL).
 */
static int atmel_verify_port(struct uart_port *port, struct serial_struct *ser)
{
        int ret = 0;
        if (ser->type != PORT_UNKNOWN && ser->type != PORT_ATMEL)
                ret = -EINVAL;
        if (port->irq != ser->irq)
                ret = -EINVAL;
        if (ser->io_type != SERIAL_IO_MEM)
                ret = -EINVAL;
        if (port->uartclk / 16 != ser->baud_base)
                ret = -EINVAL;
        if ((void *)port->mapbase != ser->iomem_base)
                ret = -EINVAL;
        if (port->iobase != ser->port)
                ret = -EINVAL;
        if (ser->hub6 != 0)
                ret = -EINVAL;
        return ret;
}

#ifdef CONFIG_CONSOLE_POLL
static int atmel_poll_get_char(struct uart_port *port)
{
        while (!(UART_GET_CSR(port) & ATMEL_US_RXRDY))
                cpu_relax();

        return UART_GET_CHAR(port);
}

static void atmel_poll_put_char(struct uart_port *port, unsigned char ch)
{
        while (!(UART_GET_CSR(port) & ATMEL_US_TXRDY))
                cpu_relax();

        UART_PUT_CHAR(port, ch);
}
#endif

static int
atmel_ioctl(struct uart_port *port, unsigned int cmd, unsigned long arg)
{
        struct serial_rs485 rs485conf;

        switch (cmd) {
        case TIOCSRS485:
                if (copy_from_user(&rs485conf, (struct serial_rs485 *) arg,
                                        sizeof(rs485conf)))
                        return -EFAULT;

                atmel_config_rs485(port, &rs485conf);
                break;

        case TIOCGRS485:
                if (copy_to_user((struct serial_rs485 *) arg,
                                        &(to_atmel_uart_port(port)->rs485),
                                        sizeof(rs485conf)))
                        return -EFAULT;
                break;

        default:
                return -ENOIOCTLCMD;
        }
        return 0;
}



static struct uart_ops atmel_pops = {
        .tx_empty       = atmel_tx_empty,
        .set_mctrl      = atmel_set_mctrl,
        .get_mctrl      = atmel_get_mctrl,
        .stop_tx        = atmel_stop_tx,
        .start_tx       = atmel_start_tx,
        .stop_rx        = atmel_stop_rx,
        .enable_ms      = atmel_enable_ms,
        .break_ctl      = atmel_break_ctl,
        .startup        = atmel_startup,
        .shutdown       = atmel_shutdown,
        .flush_buffer   = atmel_flush_buffer,
        .set_termios    = atmel_set_termios,
        .set_ldisc      = atmel_set_ldisc,
        .type           = atmel_type,
        .release_port   = atmel_release_port,
        .request_port   = atmel_request_port,
        .config_port    = atmel_config_port,
        .verify_port    = atmel_verify_port,
        .pm             = atmel_serial_pm,
        .ioctl          = atmel_ioctl,
#ifdef CONFIG_CONSOLE_POLL
        .poll_get_char  = atmel_poll_get_char,
        .poll_put_char  = atmel_poll_put_char,
#endif
};

static void atmel_of_init_port(struct atmel_uart_port *atmel_port,
                                         struct device_node *np)
{
        u32 rs485_delay[2];

        /* DMA/PDC usage specification */
        if (of_get_property(np, "atmel,use-dma-rx", NULL))
                atmel_port->use_dma_rx  = 1;
        else
                atmel_port->use_dma_rx  = 0;
        if (of_get_property(np, "atmel,use-dma-tx", NULL))
                atmel_port->use_dma_tx  = 1;
        else
                atmel_port->use_dma_tx  = 0;

        /* rs485 properties */
        if (of_property_read_u32_array(np, "rs485-rts-delay",
                                            rs485_delay, 2) == 0) {
                struct serial_rs485 *rs485conf = &atmel_port->rs485;

                rs485conf->delay_rts_before_send = rs485_delay[0];
                rs485conf->delay_rts_after_send = rs485_delay[1];
                rs485conf->flags = 0;

                if (of_get_property(np, "rs485-rx-during-tx", NULL))
                        rs485conf->flags |= SER_RS485_RX_DURING_TX;

                if (of_get_property(np, "linux,rs485-enabled-at-boot-time", NULL))
                        rs485conf->flags |= SER_RS485_ENABLED;
        }
}

/*
 * Configure the port from the platform device resource info.
 */
static int atmel_init_port(struct atmel_uart_port *atmel_port,
                                      struct platform_device *pdev)
{
        int ret;
        struct uart_port *port = &atmel_port->uart;
        struct atmel_uart_data *pdata = pdev->dev.platform_data;

        if (pdev->dev.of_node) {
                atmel_of_init_port(atmel_port, pdev->dev.of_node);
        } else {
                atmel_port->use_dma_rx  = pdata->use_dma_rx;
                atmel_port->use_dma_tx  = pdata->use_dma_tx;
                atmel_port->rs485       = pdata->rs485;
        }

        port->iotype            = UPIO_MEM;
        port->flags             = UPF_BOOT_AUTOCONF;
        port->ops               = &atmel_pops;
        port->fifosize          = 1;
        port->dev               = &pdev->dev;
        port->mapbase   = pdev->resource[0].start;
        port->irq       = pdev->resource[1].start;

        tasklet_init(&atmel_port->tasklet, atmel_tasklet_func,
                        (unsigned long)port);

        memset(&atmel_port->rx_ring, 0, sizeof(atmel_port->rx_ring));

        if (pdata && pdata->regs) {
                /* Already mapped by setup code */
                port->membase = pdata->regs;
        } else {
                port->flags     |= UPF_IOREMAP;
                port->membase   = NULL;
        }

        /* for console, the clock could already be configured */
        if (!atmel_port->clk) {
                atmel_port->clk = clk_get(&pdev->dev, "usart");
                if (IS_ERR(atmel_port->clk)) {
                        ret = PTR_ERR(atmel_port->clk);
                        atmel_port->clk = NULL;
                        return ret;
                }
                ret = clk_prepare_enable(atmel_port->clk);
                if (ret) {
                        clk_put(atmel_port->clk);
                        atmel_port->clk = NULL;
                        return ret;
                }
                port->uartclk = clk_get_rate(atmel_port->clk);
                clk_disable_unprepare(atmel_port->clk);
                /* only enable clock when USART is in use */
        }

        /* Use TXEMPTY for interrupt when rs485 else TXRDY or ENDTX|TXBUFE */
        if (atmel_port->rs485.flags & SER_RS485_ENABLED)
                atmel_port->tx_done_mask = ATMEL_US_TXEMPTY;
        else if (atmel_use_dma_tx(port)) {
                port->fifosize = PDC_BUFFER_SIZE;
                atmel_port->tx_done_mask = ATMEL_US_ENDTX | ATMEL_US_TXBUFE;
        } else {
                atmel_port->tx_done_mask = ATMEL_US_TXRDY;
        }

        return 0;
}

struct platform_device *atmel_default_console_device;   /* the serial console device */

#ifdef CONFIG_SERIAL_ATMEL_CONSOLE
static void atmel_console_putchar(struct uart_port *port, int ch)
{
        while (!(UART_GET_CSR(port) & ATMEL_US_TXRDY))
                cpu_relax();
        UART_PUT_CHAR(port, ch);
}

/*
 * Interrupts are disabled on entering
 */
static void atmel_console_write(struct console *co, const char *s, u_int count)
{
        struct uart_port *port = &atmel_ports[co->index].uart;
        struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
        unsigned int status, imr;
        unsigned int pdc_tx;

        /*
         * First, save IMR and then disable interrupts
         */
        imr = UART_GET_IMR(port);
        UART_PUT_IDR(port, ATMEL_US_RXRDY | atmel_port->tx_done_mask);

        /* Store PDC transmit status and disable it */
        pdc_tx = UART_GET_PTSR(port) & ATMEL_PDC_TXTEN;
        UART_PUT_PTCR(port, ATMEL_PDC_TXTDIS);

        uart_console_write(port, s, count, atmel_console_putchar);

        /*
         * Finally, wait for transmitter to become empty
         * and restore IMR
         */
        do {
                status = UART_GET_CSR(port);
        } while (!(status & ATMEL_US_TXRDY));

        /* Restore PDC transmit status */
        if (pdc_tx)
                UART_PUT_PTCR(port, ATMEL_PDC_TXTEN);

        /* set interrupts back the way they were */
        UART_PUT_IER(port, imr);
}

/*
 * If the port was already initialised (eg, by a boot loader),
 * try to determine the current setup.
 */
static void __init atmel_console_get_options(struct uart_port *port, int *baud,
                                             int *parity, int *bits)
{
        unsigned int mr, quot;

        /*
         * If the baud rate generator isn't running, the port wasn't
         * initialized by the boot loader.
         */
        quot = UART_GET_BRGR(port) & ATMEL_US_CD;
        if (!quot)
                return;

        mr = UART_GET_MR(port) & ATMEL_US_CHRL;
        if (mr == ATMEL_US_CHRL_8)
                *bits = 8;
        else
                *bits = 7;

        mr = UART_GET_MR(port) & ATMEL_US_PAR;
        if (mr == ATMEL_US_PAR_EVEN)
                *parity = 'e';
        else if (mr == ATMEL_US_PAR_ODD)
                *parity = 'o';

        /*
         * The serial core only rounds down when matching this to a
         * supported baud rate. Make sure we don't end up slightly
         * lower than one of those, as it would make us fall through
         * to a much lower baud rate than we really want.
         */
        *baud = port->uartclk / (16 * (quot - 1));
}

static int __init atmel_console_setup(struct console *co, char *options)
{
        int ret;
        struct uart_port *port = &atmel_ports[co->index].uart;
        int baud = 115200;
        int bits = 8;
        int parity = 'n';
        int flow = 'n';

        if (port->membase == NULL) {
                /* Port not initialized yet - delay setup */
                return -ENODEV;
        }

        ret = clk_prepare_enable(atmel_ports[co->index].clk);
        if (ret)
                return ret;

        UART_PUT_IDR(port, -1);
        UART_PUT_CR(port, ATMEL_US_RSTSTA | ATMEL_US_RSTRX);
        UART_PUT_CR(port, ATMEL_US_TXEN | ATMEL_US_RXEN);

        if (options)
                uart_parse_options(options, &baud, &parity, &bits, &flow);
        else
                atmel_console_get_options(port, &baud, &parity, &bits);

        return uart_set_options(port, co, baud, parity, bits, flow);
}

static struct uart_driver atmel_uart;

static struct console atmel_console = {
        .name           = ATMEL_DEVICENAME,
        .write          = atmel_console_write,
        .device         = uart_console_device,
        .setup          = atmel_console_setup,
        .flags          = CON_PRINTBUFFER,
        .index          = -1,
        .data           = &atmel_uart,
};

#define ATMEL_CONSOLE_DEVICE    (&atmel_console)

/*
 * Early console initialization (before VM subsystem initialized).
 */
static int __init atmel_console_init(void)
{
        int ret;
        if (atmel_default_console_device) {
                struct atmel_uart_data *pdata =
                        atmel_default_console_device->dev.platform_data;
                int id = pdata->num;
                struct atmel_uart_port *port = &atmel_ports[id];

                port->backup_imr = 0;
                port->uart.line = id;

                add_preferred_console(ATMEL_DEVICENAME, id, NULL);
                ret = atmel_init_port(port, atmel_default_console_device);
                if (ret)
                        return ret;
                register_console(&atmel_console);
        }

        return 0;
}

console_initcall(atmel_console_init);

/*
 * Late console initialization.
 */
static int __init atmel_late_console_init(void)
{
        if (atmel_default_console_device
            && !(atmel_console.flags & CON_ENABLED))
                register_console(&atmel_console);

        return 0;
}

core_initcall(atmel_late_console_init);

static inline bool atmel_is_console_port(struct uart_port *port)
{
        return port->cons && port->cons->index == port->line;
}

#else
#define ATMEL_CONSOLE_DEVICE    NULL

static inline bool atmel_is_console_port(struct uart_port *port)
{
        return false;
}
#endif

static struct uart_driver atmel_uart = {
        .owner          = THIS_MODULE,
        .driver_name    = "atmel_serial",
        .dev_name       = ATMEL_DEVICENAME,
        .major          = SERIAL_ATMEL_MAJOR,
        .minor          = MINOR_START,
        .nr             = ATMEL_MAX_UART,
        .cons           = ATMEL_CONSOLE_DEVICE,
};

#ifdef CONFIG_PM
static bool atmel_serial_clk_will_stop(void)
{
#ifdef CONFIG_ARCH_AT91
        return at91_suspend_entering_slow_clock();
#else
        return false;
#endif
}

static int atmel_serial_suspend(struct platform_device *pdev,
                                pm_message_t state)
{
        struct uart_port *port = platform_get_drvdata(pdev);
        struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);

        if (atmel_is_console_port(port) && console_suspend_enabled) {
                /* Drain the TX shifter */
                while (!(UART_GET_CSR(port) & ATMEL_US_TXEMPTY))
                        cpu_relax();
        }

        /* we can not wake up if we're running on slow clock */
        atmel_port->may_wakeup = device_may_wakeup(&pdev->dev);
        if (atmel_serial_clk_will_stop())
                device_set_wakeup_enable(&pdev->dev, 0);

        uart_suspend_port(&atmel_uart, port);

        return 0;
}

static int atmel_serial_resume(struct platform_device *pdev)
{
        struct uart_port *port = platform_get_drvdata(pdev);
        struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);

        uart_resume_port(&atmel_uart, port);
        device_set_wakeup_enable(&pdev->dev, atmel_port->may_wakeup);

        return 0;
}
#else
#define atmel_serial_suspend NULL
#define atmel_serial_resume NULL
#endif

static int atmel_serial_probe(struct platform_device *pdev)
{
        struct atmel_uart_port *port;
        struct device_node *np = pdev->dev.of_node;
        struct atmel_uart_data *pdata = pdev->dev.platform_data;
        void *data;
        int ret = -ENODEV;
        struct pinctrl *pinctrl;

        BUILD_BUG_ON(ATMEL_SERIAL_RINGSIZE & (ATMEL_SERIAL_RINGSIZE - 1));

        if (np)
                ret = of_alias_get_id(np, "serial");
        else
                if (pdata)
                        ret = pdata->num;

        if (ret < 0)
                /* port id not found in platform data nor device-tree aliases:
                 * auto-enumerate it */
                ret = find_first_zero_bit(atmel_ports_in_use, ATMEL_MAX_UART);

        if (ret >= ATMEL_MAX_UART) {
                ret = -ENODEV;
                goto err;
        }

        if (test_and_set_bit(ret, atmel_ports_in_use)) {
                /* port already in use */
                ret = -EBUSY;
                goto err;
        }

        port = &atmel_ports[ret];
        port->backup_imr = 0;
        port->uart.line = ret;

        ret = atmel_init_port(port, pdev);
        if (ret)
                goto err;

        pinctrl = devm_pinctrl_get_select_default(&pdev->dev);
        if (IS_ERR(pinctrl)) {
                ret = PTR_ERR(pinctrl);
                goto err;
        }

        if (!atmel_use_dma_rx(&port->uart)) {
                ret = -ENOMEM;
                data = kmalloc(sizeof(struct atmel_uart_char)
                                * ATMEL_SERIAL_RINGSIZE, GFP_KERNEL);
                if (!data)
                        goto err_alloc_ring;
                port->rx_ring.buf = data;
        }

        ret = uart_add_one_port(&atmel_uart, &port->uart);
        if (ret)
                goto err_add_port;

#ifdef CONFIG_SERIAL_ATMEL_CONSOLE
        if (atmel_is_console_port(&port->uart)
                        && ATMEL_CONSOLE_DEVICE->flags & CON_ENABLED) {
                /*
                 * The serial core enabled the clock for us, so undo
                 * the clk_prepare_enable() in atmel_console_setup()
                 */
                clk_disable_unprepare(port->clk);
        }
#endif

        device_init_wakeup(&pdev->dev, 1);
        platform_set_drvdata(pdev, port);

        if (port->rs485.flags & SER_RS485_ENABLED) {
                UART_PUT_MR(&port->uart, ATMEL_US_USMODE_NORMAL);
                UART_PUT_CR(&port->uart, ATMEL_US_RTSEN);
        }

        return 0;

err_add_port:
        kfree(port->rx_ring.buf);
        port->rx_ring.buf = NULL;
err_alloc_ring:
        if (!atmel_is_console_port(&port->uart)) {
                clk_put(port->clk);
                port->clk = NULL;
        }
err:
        return ret;
}

static int atmel_serial_remove(struct platform_device *pdev)
{
        struct uart_port *port = platform_get_drvdata(pdev);
        struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
        int ret = 0;

        device_init_wakeup(&pdev->dev, 0);
        platform_set_drvdata(pdev, NULL);

        ret = uart_remove_one_port(&atmel_uart, port);

        tasklet_kill(&atmel_port->tasklet);
        kfree(atmel_port->rx_ring.buf);

        /* "port" is allocated statically, so we shouldn't free it */

        clear_bit(port->line, atmel_ports_in_use);

        clk_put(atmel_port->clk);

        return ret;
}

static struct platform_driver atmel_serial_driver = {
        .probe          = atmel_serial_probe,
        .remove         = atmel_serial_remove,
        .suspend        = atmel_serial_suspend,
        .resume         = atmel_serial_resume,
        .driver         = {
                .name   = "atmel_usart",
                .owner  = THIS_MODULE,
                .of_match_table = of_match_ptr(atmel_serial_dt_ids),
        },
};

static int __init atmel_serial_init(void)
{
        int ret;

        ret = uart_register_driver(&atmel_uart);
        if (ret)
                return ret;

        ret = platform_driver_register(&atmel_serial_driver);
        if (ret)
                uart_unregister_driver(&atmel_uart);

        return ret;
}

static void __exit atmel_serial_exit(void)
{
        platform_driver_unregister(&atmel_serial_driver);
        uart_unregister_driver(&atmel_uart);
}

module_init(atmel_serial_init);
module_exit(atmel_serial_exit);

MODULE_AUTHOR("Rick Bronson");
MODULE_DESCRIPTION("Atmel AT91 / AT32 serial port driver");
MODULE_LICENSE("GPL");
MODULE_ALIAS("platform:atmel_usart");