/*
 * Driver for the PSC of the Freescale MPC52xx PSCs configured as UARTs.
 *
 * FIXME According to the usermanual the status bits in the status register
 * are only updated when the peripherals access the FIFO and not when the
 * CPU access them. So since we use this bits to know when we stop writing
 * and reading, they may not be updated in-time and a race condition may
 * exists. But I haven't be able to prove this and I don't care. But if
 * any problem arises, it might worth checking. The TX/RX FIFO Stats
 * registers should be used in addition.
 * Update: Actually, they seem updated ... At least the bits we use.
 *
 *
 * Maintainer : Sylvain Munaut <tnt@246tNt.com>
 *
 * Some of the code has been inspired/copied from the 2.4 code written
 * by Dale Farnsworth <dfarnsworth@mvista.com>.
 *
 * Copyright (C) 2008 Freescale Semiconductor Inc.
 *                    John Rigby <jrigby@gmail.com>
 * Added support for MPC5121
 * Copyright (C) 2006 Secret Lab Technologies Ltd.
 *                    Grant Likely <grant.likely@secretlab.ca>
 * Copyright (C) 2004-2006 Sylvain Munaut <tnt@246tNt.com>
 * Copyright (C) 2003 MontaVista, Software, Inc.
 *
 * This file is licensed under the terms of the GNU General Public License
 * version 2. This program is licensed "as is" without any warranty of any
 * kind, whether express or implied.
 */

/* Platform device Usage :
 *
 * Since PSCs can have multiple function, the correct driver for each one
 * is selected by calling mpc52xx_match_psc_function(...). The function
 * handled by this driver is "uart".
 *
 * The driver init all necessary registers to place the PSC in uart mode without
 * DCD. However, the pin multiplexing aren't changed and should be set either
 * by the bootloader or in the platform init code.
 *
 * The idx field must be equal to the PSC index (e.g. 0 for PSC1, 1 for PSC2,
 * and so on). So the PSC1 is mapped to /dev/ttyPSC0, PSC2 to /dev/ttyPSC1 and
 * so on. But be warned, it's an ABSOLUTE REQUIREMENT ! This is needed mainly
 * fpr the console code : without this 1:1 mapping, at early boot time, when we
 * are parsing the kernel args console=ttyPSC?, we wouldn't know which PSC it
 * will be mapped to.
 */

/* OF Platform device Usage :
 *
 * This driver is only used for PSCs configured in uart mode.  The device
 * tree will have a node for each PSC in uart mode w/ device_type = "serial"
 * and "mpc52xx-psc-uart" in the compatible string
 *
 * By default, PSC devices are enumerated in the order they are found.  However
 * a particular PSC number can be forces by adding 'device_no = <port#>'
 * to the device node.
 *
 * The driver init all necessary registers to place the PSC in uart mode without
 * DCD. However, the pin multiplexing aren't changed and should be set either
 * by the bootloader or in the platform init code.
 */

#undef DEBUG

#include <linux/device.h>
#include <linux/module.h>
#include <linux/tty.h>
#include <linux/serial.h>
#include <linux/sysrq.h>
#include <linux/console.h>
#include <linux/delay.h>
#include <linux/io.h>
#include <linux/of.h>
#include <linux/of_platform.h>

#include <asm/mpc52xx.h>
#include <asm/mpc512x.h>
#include <asm/mpc52xx_psc.h>

#if defined(CONFIG_SERIAL_MPC52xx_CONSOLE) && defined(CONFIG_MAGIC_SYSRQ)
#define SUPPORT_SYSRQ
#endif

#include <linux/serial_core.h>


/* We've been assigned a range on the "Low-density serial ports" major */
#define SERIAL_PSC_MAJOR        204
#define SERIAL_PSC_MINOR        148


#define ISR_PASS_LIMIT 256      /* Max number of iteration in the interrupt */


static struct uart_port mpc52xx_uart_ports[MPC52xx_PSC_MAXNUM];
        /* Rem: - We use the read_status_mask as a shadow of
         *        psc->mpc52xx_psc_imr
         *      - It's important that is array is all zero on start as we
         *        use it to know if it's initialized or not ! If it's not sure
         *        it's cleared, then a memset(...,0,...) should be added to
         *        the console_init
         */

/* lookup table for matching device nodes to index numbers */
static struct device_node *mpc52xx_uart_nodes[MPC52xx_PSC_MAXNUM];

static void mpc52xx_uart_of_enumerate(void);


#define PSC(port) ((struct mpc52xx_psc __iomem *)((port)->membase))


/* Forward declaration of the interruption handling routine */
static irqreturn_t mpc52xx_uart_int(int irq, void *dev_id);


/* Simple macro to test if a port is console or not. This one is taken
 * for serial_core.c and maybe should be moved to serial_core.h ? */
#ifdef CONFIG_SERIAL_CORE_CONSOLE
#define uart_console(port) \
        ((port)->cons && (port)->cons->index == (port)->line)
#else
#define uart_console(port)      (0)
#endif

/* ======================================================================== */
/* PSC fifo operations for isolating differences between 52xx and 512x      */
/* ======================================================================== */

struct psc_ops {
        void            (*fifo_init)(struct uart_port *port);
        int             (*raw_rx_rdy)(struct uart_port *port);
        int             (*raw_tx_rdy)(struct uart_port *port);
        int             (*rx_rdy)(struct uart_port *port);
        int             (*tx_rdy)(struct uart_port *port);
        int             (*tx_empty)(struct uart_port *port);
        void            (*stop_rx)(struct uart_port *port);
        void            (*start_tx)(struct uart_port *port);
        void            (*stop_tx)(struct uart_port *port);
        void            (*rx_clr_irq)(struct uart_port *port);
        void            (*tx_clr_irq)(struct uart_port *port);
        void            (*write_char)(struct uart_port *port, unsigned char c);
        unsigned char   (*read_char)(struct uart_port *port);
        void            (*cw_disable_ints)(struct uart_port *port);
        void            (*cw_restore_ints)(struct uart_port *port);
        unsigned long   (*getuartclk)(void *p);
};

#ifdef CONFIG_PPC_MPC52xx
#define FIFO_52xx(port) ((struct mpc52xx_psc_fifo __iomem *)(PSC(port)+1))
static void mpc52xx_psc_fifo_init(struct uart_port *port)
{
        struct mpc52xx_psc __iomem *psc = PSC(port);
        struct mpc52xx_psc_fifo __iomem *fifo = FIFO_52xx(port);

        /* /32 prescaler */
        out_be16(&psc->mpc52xx_psc_clock_select, 0xdd00);

        out_8(&fifo->rfcntl, 0x00);
        out_be16(&fifo->rfalarm, 0x1ff);
        out_8(&fifo->tfcntl, 0x07);
        out_be16(&fifo->tfalarm, 0x80);

        port->read_status_mask |= MPC52xx_PSC_IMR_RXRDY | MPC52xx_PSC_IMR_TXRDY;
        out_be16(&psc->mpc52xx_psc_imr, port->read_status_mask);
}

static int mpc52xx_psc_raw_rx_rdy(struct uart_port *port)
{
        return in_be16(&PSC(port)->mpc52xx_psc_status)
            & MPC52xx_PSC_SR_RXRDY;
}

static int mpc52xx_psc_raw_tx_rdy(struct uart_port *port)
{
        return in_be16(&PSC(port)->mpc52xx_psc_status)
            & MPC52xx_PSC_SR_TXRDY;
}


static int mpc52xx_psc_rx_rdy(struct uart_port *port)
{
        return in_be16(&PSC(port)->mpc52xx_psc_isr)
            & port->read_status_mask
            & MPC52xx_PSC_IMR_RXRDY;
}

static int mpc52xx_psc_tx_rdy(struct uart_port *port)
{
        return in_be16(&PSC(port)->mpc52xx_psc_isr)
            & port->read_status_mask
            & MPC52xx_PSC_IMR_TXRDY;
}

static int mpc52xx_psc_tx_empty(struct uart_port *port)
{
        return in_be16(&PSC(port)->mpc52xx_psc_status)
            & MPC52xx_PSC_SR_TXEMP;
}

static void mpc52xx_psc_start_tx(struct uart_port *port)
{
        port->read_status_mask |= MPC52xx_PSC_IMR_TXRDY;
        out_be16(&PSC(port)->mpc52xx_psc_imr, port->read_status_mask);
}

static void mpc52xx_psc_stop_tx(struct uart_port *port)
{
        port->read_status_mask &= ~MPC52xx_PSC_IMR_TXRDY;
        out_be16(&PSC(port)->mpc52xx_psc_imr, port->read_status_mask);
}

static void mpc52xx_psc_stop_rx(struct uart_port *port)
{
        port->read_status_mask &= ~MPC52xx_PSC_IMR_RXRDY;
        out_be16(&PSC(port)->mpc52xx_psc_imr, port->read_status_mask);
}

static void mpc52xx_psc_rx_clr_irq(struct uart_port *port)
{
}

static void mpc52xx_psc_tx_clr_irq(struct uart_port *port)
{
}

static void mpc52xx_psc_write_char(struct uart_port *port, unsigned char c)
{
        out_8(&PSC(port)->mpc52xx_psc_buffer_8, c);
}

static unsigned char mpc52xx_psc_read_char(struct uart_port *port)
{
        return in_8(&PSC(port)->mpc52xx_psc_buffer_8);
}

static void mpc52xx_psc_cw_disable_ints(struct uart_port *port)
{
        out_be16(&PSC(port)->mpc52xx_psc_imr, 0);
}

static void mpc52xx_psc_cw_restore_ints(struct uart_port *port)
{
        out_be16(&PSC(port)->mpc52xx_psc_imr, port->read_status_mask);
}

/* Search for bus-frequency property in this node or a parent */
static unsigned long mpc52xx_getuartclk(void *p)
{
        /*
         * 5200 UARTs have a / 32 prescaler
         * but the generic serial code assumes 16
         * so return ipb freq / 2
         */
        return mpc52xx_find_ipb_freq(p) / 2;
}

static struct psc_ops mpc52xx_psc_ops = {
        .fifo_init = mpc52xx_psc_fifo_init,
        .raw_rx_rdy = mpc52xx_psc_raw_rx_rdy,
        .raw_tx_rdy = mpc52xx_psc_raw_tx_rdy,
        .rx_rdy = mpc52xx_psc_rx_rdy,
        .tx_rdy = mpc52xx_psc_tx_rdy,
        .tx_empty = mpc52xx_psc_tx_empty,
        .stop_rx = mpc52xx_psc_stop_rx,
        .start_tx = mpc52xx_psc_start_tx,
        .stop_tx = mpc52xx_psc_stop_tx,
        .rx_clr_irq = mpc52xx_psc_rx_clr_irq,
        .tx_clr_irq = mpc52xx_psc_tx_clr_irq,
        .write_char = mpc52xx_psc_write_char,
        .read_char = mpc52xx_psc_read_char,
        .cw_disable_ints = mpc52xx_psc_cw_disable_ints,
        .cw_restore_ints = mpc52xx_psc_cw_restore_ints,
        .getuartclk = mpc52xx_getuartclk,
};

#endif /* CONFIG_MPC52xx */

#ifdef CONFIG_PPC_MPC512x
#define FIFO_512x(port) ((struct mpc512x_psc_fifo __iomem *)(PSC(port)+1))
static void mpc512x_psc_fifo_init(struct uart_port *port)
{
        out_be32(&FIFO_512x(port)->txcmd, MPC512x_PSC_FIFO_RESET_SLICE);
        out_be32(&FIFO_512x(port)->txcmd, MPC512x_PSC_FIFO_ENABLE_SLICE);
        out_be32(&FIFO_512x(port)->txalarm, 1);
        out_be32(&FIFO_512x(port)->tximr, 0);

        out_be32(&FIFO_512x(port)->rxcmd, MPC512x_PSC_FIFO_RESET_SLICE);
        out_be32(&FIFO_512x(port)->rxcmd, MPC512x_PSC_FIFO_ENABLE_SLICE);
        out_be32(&FIFO_512x(port)->rxalarm, 1);
        out_be32(&FIFO_512x(port)->rximr, 0);

        out_be32(&FIFO_512x(port)->tximr, MPC512x_PSC_FIFO_ALARM);
        out_be32(&FIFO_512x(port)->rximr, MPC512x_PSC_FIFO_ALARM);
}

static int mpc512x_psc_raw_rx_rdy(struct uart_port *port)
{
        return !(in_be32(&FIFO_512x(port)->rxsr) & MPC512x_PSC_FIFO_EMPTY);
}

static int mpc512x_psc_raw_tx_rdy(struct uart_port *port)
{
        return !(in_be32(&FIFO_512x(port)->txsr) & MPC512x_PSC_FIFO_FULL);
}

static int mpc512x_psc_rx_rdy(struct uart_port *port)
{
        return in_be32(&FIFO_512x(port)->rxsr)
            & in_be32(&FIFO_512x(port)->rximr)
            & MPC512x_PSC_FIFO_ALARM;
}

static int mpc512x_psc_tx_rdy(struct uart_port *port)
{
        return in_be32(&FIFO_512x(port)->txsr)
            & in_be32(&FIFO_512x(port)->tximr)
            & MPC512x_PSC_FIFO_ALARM;
}

static int mpc512x_psc_tx_empty(struct uart_port *port)
{
        return in_be32(&FIFO_512x(port)->txsr)
            & MPC512x_PSC_FIFO_EMPTY;
}

static void mpc512x_psc_stop_rx(struct uart_port *port)
{
        unsigned long rx_fifo_imr;

        rx_fifo_imr = in_be32(&FIFO_512x(port)->rximr);
        rx_fifo_imr &= ~MPC512x_PSC_FIFO_ALARM;
        out_be32(&FIFO_512x(port)->rximr, rx_fifo_imr);
}

static void mpc512x_psc_start_tx(struct uart_port *port)
{
        unsigned long tx_fifo_imr;

        tx_fifo_imr = in_be32(&FIFO_512x(port)->tximr);
        tx_fifo_imr |= MPC512x_PSC_FIFO_ALARM;
        out_be32(&FIFO_512x(port)->tximr, tx_fifo_imr);
}

static void mpc512x_psc_stop_tx(struct uart_port *port)
{
        unsigned long tx_fifo_imr;

        tx_fifo_imr = in_be32(&FIFO_512x(port)->tximr);
        tx_fifo_imr &= ~MPC512x_PSC_FIFO_ALARM;
        out_be32(&FIFO_512x(port)->tximr, tx_fifo_imr);
}

static void mpc512x_psc_rx_clr_irq(struct uart_port *port)
{
        out_be32(&FIFO_512x(port)->rxisr, in_be32(&FIFO_512x(port)->rxisr));
}

static void mpc512x_psc_tx_clr_irq(struct uart_port *port)
{
        out_be32(&FIFO_512x(port)->txisr, in_be32(&FIFO_512x(port)->txisr));
}

static void mpc512x_psc_write_char(struct uart_port *port, unsigned char c)
{
        out_8(&FIFO_512x(port)->txdata_8, c);
}

static unsigned char mpc512x_psc_read_char(struct uart_port *port)
{
        return in_8(&FIFO_512x(port)->rxdata_8);
}

static void mpc512x_psc_cw_disable_ints(struct uart_port *port)
{
        port->read_status_mask =
                in_be32(&FIFO_512x(port)->tximr) << 16 |
                in_be32(&FIFO_512x(port)->rximr);
        out_be32(&FIFO_512x(port)->tximr, 0);
        out_be32(&FIFO_512x(port)->rximr, 0);
}

static void mpc512x_psc_cw_restore_ints(struct uart_port *port)
{
        out_be32(&FIFO_512x(port)->tximr,
                (port->read_status_mask >> 16) & 0x7f);
        out_be32(&FIFO_512x(port)->rximr, port->read_status_mask & 0x7f);
}

static unsigned long mpc512x_getuartclk(void *p)
{
        return mpc512x_find_ips_freq(p);
}

static struct psc_ops mpc512x_psc_ops = {
        .fifo_init = mpc512x_psc_fifo_init,
        .raw_rx_rdy = mpc512x_psc_raw_rx_rdy,
        .raw_tx_rdy = mpc512x_psc_raw_tx_rdy,
        .rx_rdy = mpc512x_psc_rx_rdy,
        .tx_rdy = mpc512x_psc_tx_rdy,
        .tx_empty = mpc512x_psc_tx_empty,
        .stop_rx = mpc512x_psc_stop_rx,
        .start_tx = mpc512x_psc_start_tx,
        .stop_tx = mpc512x_psc_stop_tx,
        .rx_clr_irq = mpc512x_psc_rx_clr_irq,
        .tx_clr_irq = mpc512x_psc_tx_clr_irq,
        .write_char = mpc512x_psc_write_char,
        .read_char = mpc512x_psc_read_char,
        .cw_disable_ints = mpc512x_psc_cw_disable_ints,
        .cw_restore_ints = mpc512x_psc_cw_restore_ints,
        .getuartclk = mpc512x_getuartclk,
};
#endif

static struct psc_ops *psc_ops;

/* ======================================================================== */
/* UART operations                                                          */
/* ======================================================================== */

static unsigned int
mpc52xx_uart_tx_empty(struct uart_port *port)
{
        return psc_ops->tx_empty(port) ? TIOCSER_TEMT : 0;
}

static void
mpc52xx_uart_set_mctrl(struct uart_port *port, unsigned int mctrl)
{
        /* Not implemented */
}

static unsigned int
mpc52xx_uart_get_mctrl(struct uart_port *port)
{
        /* Not implemented */
        return TIOCM_CTS | TIOCM_DSR | TIOCM_CAR;
}

static void
mpc52xx_uart_stop_tx(struct uart_port *port)
{
        /* port->lock taken by caller */
        psc_ops->stop_tx(port);
}

static void
mpc52xx_uart_start_tx(struct uart_port *port)
{
        /* port->lock taken by caller */
        psc_ops->start_tx(port);
}

static void
mpc52xx_uart_send_xchar(struct uart_port *port, char ch)
{
        unsigned long flags;
        spin_lock_irqsave(&port->lock, flags);

        port->x_char = ch;
        if (ch) {
                /* Make sure tx interrupts are on */
                /* Truly necessary ??? They should be anyway */
                psc_ops->start_tx(port);
        }

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

static void
mpc52xx_uart_stop_rx(struct uart_port *port)
{
        /* port->lock taken by caller */
        psc_ops->stop_rx(port);
}

static void
mpc52xx_uart_enable_ms(struct uart_port *port)
{
        /* Not implemented */
}

static void
mpc52xx_uart_break_ctl(struct uart_port *port, int ctl)
{
        unsigned long flags;
        spin_lock_irqsave(&port->lock, flags);

        if (ctl == -1)
                out_8(&PSC(port)->command, MPC52xx_PSC_START_BRK);
        else
                out_8(&PSC(port)->command, MPC52xx_PSC_STOP_BRK);

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

static int
mpc52xx_uart_startup(struct uart_port *port)
{
        struct mpc52xx_psc __iomem *psc = PSC(port);
        int ret;

        /* Request IRQ */
        ret = request_irq(port->irq, mpc52xx_uart_int,
                IRQF_DISABLED | IRQF_SAMPLE_RANDOM | IRQF_SHARED,
                "mpc52xx_psc_uart", port);
        if (ret)
                return ret;

        /* Reset/activate the port, clear and enable interrupts */
        out_8(&psc->command, MPC52xx_PSC_RST_RX);
        out_8(&psc->command, MPC52xx_PSC_RST_TX);

        out_be32(&psc->sicr, 0);        /* UART mode DCD ignored */

        psc_ops->fifo_init(port);

        out_8(&psc->command, MPC52xx_PSC_TX_ENABLE);
        out_8(&psc->command, MPC52xx_PSC_RX_ENABLE);

        return 0;
}

static void
mpc52xx_uart_shutdown(struct uart_port *port)
{
        struct mpc52xx_psc __iomem *psc = PSC(port);

        /* Shut down the port.  Leave TX active if on a console port */
        out_8(&psc->command, MPC52xx_PSC_RST_RX);
        if (!uart_console(port))
                out_8(&psc->command, MPC52xx_PSC_RST_TX);

        port->read_status_mask = 0;
        out_be16(&psc->mpc52xx_psc_imr, port->read_status_mask);

        /* Release interrupt */
        free_irq(port->irq, port);
}

static void
mpc52xx_uart_set_termios(struct uart_port *port, struct ktermios *new,
                         struct ktermios *old)
{
        struct mpc52xx_psc __iomem *psc = PSC(port);
        unsigned long flags;
        unsigned char mr1, mr2;
        unsigned short ctr;
        unsigned int j, baud, quot;

        /* Prepare what we're gonna write */
        mr1 = 0;

        switch (new->c_cflag & CSIZE) {
        case CS5:       mr1 |= MPC52xx_PSC_MODE_5_BITS;
                break;
        case CS6:       mr1 |= MPC52xx_PSC_MODE_6_BITS;
                break;
        case CS7:       mr1 |= MPC52xx_PSC_MODE_7_BITS;
                break;
        case CS8:
        default:        mr1 |= MPC52xx_PSC_MODE_8_BITS;
        }

        if (new->c_cflag & PARENB) {
                mr1 |= (new->c_cflag & PARODD) ?
                        MPC52xx_PSC_MODE_PARODD : MPC52xx_PSC_MODE_PAREVEN;
        } else
                mr1 |= MPC52xx_PSC_MODE_PARNONE;


        mr2 = 0;

        if (new->c_cflag & CSTOPB)
                mr2 |= MPC52xx_PSC_MODE_TWO_STOP;
        else
                mr2 |= ((new->c_cflag & CSIZE) == CS5) ?
                        MPC52xx_PSC_MODE_ONE_STOP_5_BITS :
                        MPC52xx_PSC_MODE_ONE_STOP;


        baud = uart_get_baud_rate(port, new, old, 0, port->uartclk/16);
        quot = uart_get_divisor(port, baud);
        ctr = quot & 0xffff;

        /* Get the lock */
        spin_lock_irqsave(&port->lock, flags);

        /* Update the per-port timeout */
        uart_update_timeout(port, new->c_cflag, baud);

        /* Do our best to flush TX & RX, so we don't lose anything */
        /* But we don't wait indefinitely ! */
        j = 5000000;    /* Maximum wait */
        /* FIXME Can't receive chars since set_termios might be called at early
         * boot for the console, all stuff is not yet ready to receive at that
         * time and that just makes the kernel oops */
        /* while (j-- && mpc52xx_uart_int_rx_chars(port)); */
        while (!mpc52xx_uart_tx_empty(port) && --j)
                udelay(1);

        if (!j)
                printk(KERN_ERR "mpc52xx_uart.c: "
                        "Unable to flush RX & TX fifos in-time in set_termios."
                        "Some chars may have been lost.\n");

        /* Reset the TX & RX */
        out_8(&psc->command, MPC52xx_PSC_RST_RX);
        out_8(&psc->command, MPC52xx_PSC_RST_TX);

        /* Send new mode settings */
        out_8(&psc->command, MPC52xx_PSC_SEL_MODE_REG_1);
        out_8(&psc->mode, mr1);
        out_8(&psc->mode, mr2);
        out_8(&psc->ctur, ctr >> 8);
        out_8(&psc->ctlr, ctr & 0xff);

        /* Reenable TX & RX */
        out_8(&psc->command, MPC52xx_PSC_TX_ENABLE);
        out_8(&psc->command, MPC52xx_PSC_RX_ENABLE);

        /* We're all set, release the lock */
        spin_unlock_irqrestore(&port->lock, flags);
}

static const char *
mpc52xx_uart_type(struct uart_port *port)
{
        return port->type == PORT_MPC52xx ? "MPC52xx PSC" : NULL;
}

static void
mpc52xx_uart_release_port(struct uart_port *port)
{
        /* remapped by us ? */
        if (port->flags & UPF_IOREMAP) {
                iounmap(port->membase);
                port->membase = NULL;
        }

        release_mem_region(port->mapbase, sizeof(struct mpc52xx_psc));
}

static int
mpc52xx_uart_request_port(struct uart_port *port)
{
        int err;

        if (port->flags & UPF_IOREMAP) /* Need to remap ? */
                port->membase = ioremap(port->mapbase,
                                        sizeof(struct mpc52xx_psc));

        if (!port->membase)
                return -EINVAL;

        err = request_mem_region(port->mapbase, sizeof(struct mpc52xx_psc),
                        "mpc52xx_psc_uart") != NULL ? 0 : -EBUSY;

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

        return err;
}

static void
mpc52xx_uart_config_port(struct uart_port *port, int flags)
{
        if ((flags & UART_CONFIG_TYPE)
                && (mpc52xx_uart_request_port(port) == 0))
                port->type = PORT_MPC52xx;
}

static int
mpc52xx_uart_verify_port(struct uart_port *port, struct serial_struct *ser)
{
        if (ser->type != PORT_UNKNOWN && ser->type != PORT_MPC52xx)
                return -EINVAL;

        if ((ser->irq != port->irq) ||
            (ser->io_type != SERIAL_IO_MEM) ||
            (ser->baud_base != port->uartclk)  ||
            (ser->iomem_base != (void *)port->mapbase) ||
            (ser->hub6 != 0))
                return -EINVAL;

        return 0;
}


static struct uart_ops mpc52xx_uart_ops = {
        .tx_empty       = mpc52xx_uart_tx_empty,
        .set_mctrl      = mpc52xx_uart_set_mctrl,
        .get_mctrl      = mpc52xx_uart_get_mctrl,
        .stop_tx        = mpc52xx_uart_stop_tx,
        .start_tx       = mpc52xx_uart_start_tx,
        .send_xchar     = mpc52xx_uart_send_xchar,
        .stop_rx        = mpc52xx_uart_stop_rx,
        .enable_ms      = mpc52xx_uart_enable_ms,
        .break_ctl      = mpc52xx_uart_break_ctl,
        .startup        = mpc52xx_uart_startup,
        .shutdown       = mpc52xx_uart_shutdown,
        .set_termios    = mpc52xx_uart_set_termios,
/*      .pm             = mpc52xx_uart_pm,              Not supported yet */
/*      .set_wake       = mpc52xx_uart_set_wake,        Not supported yet */
        .type           = mpc52xx_uart_type,
        .release_port   = mpc52xx_uart_release_port,
        .request_port   = mpc52xx_uart_request_port,
        .config_port    = mpc52xx_uart_config_port,
        .verify_port    = mpc52xx_uart_verify_port
};


/* ======================================================================== */
/* Interrupt handling                                                       */
/* ======================================================================== */

static inline int
mpc52xx_uart_int_rx_chars(struct uart_port *port)
{
        struct tty_struct *tty = port->info->port.tty;
        unsigned char ch, flag;
        unsigned short status;

        /* While we can read, do so ! */
        while (psc_ops->raw_rx_rdy(port)) {
                /* Get the char */
                ch = psc_ops->read_char(port);

                /* Handle sysreq char */
#ifdef SUPPORT_SYSRQ
                if (uart_handle_sysrq_char(port, ch)) {
                        port->sysrq = 0;
                        continue;
                }
#endif

                /* Store it */

                flag = TTY_NORMAL;
                port->icount.rx++;

                status = in_be16(&PSC(port)->mpc52xx_psc_status);

                if (status & (MPC52xx_PSC_SR_PE |
                              MPC52xx_PSC_SR_FE |
                              MPC52xx_PSC_SR_RB)) {

                        if (status & MPC52xx_PSC_SR_RB) {
                                flag = TTY_BREAK;
                                uart_handle_break(port);
                        } else if (status & MPC52xx_PSC_SR_PE)
                                flag = TTY_PARITY;
                        else if (status & MPC52xx_PSC_SR_FE)
                                flag = TTY_FRAME;

                        /* Clear error condition */
                        out_8(&PSC(port)->command, MPC52xx_PSC_RST_ERR_STAT);

                }
                tty_insert_flip_char(tty, ch, flag);
                if (status & MPC52xx_PSC_SR_OE) {
                        /*
                         * Overrun is special, since it's
                         * reported immediately, and doesn't
                         * affect the current character
                         */
                        tty_insert_flip_char(tty, 0, TTY_OVERRUN);
                }
        }

        spin_unlock(&port->lock);
        tty_flip_buffer_push(tty);
        spin_lock(&port->lock);

        return psc_ops->raw_rx_rdy(port);
}

static inline int
mpc52xx_uart_int_tx_chars(struct uart_port *port)
{
        struct circ_buf *xmit = &port->info->xmit;

        /* Process out of band chars */
        if (port->x_char) {
                psc_ops->write_char(port, port->x_char);
                port->icount.tx++;
                port->x_char = 0;
                return 1;
        }

        /* Nothing to do ? */
        if (uart_circ_empty(xmit) || uart_tx_stopped(port)) {
                mpc52xx_uart_stop_tx(port);
                return 0;
        }

        /* Send chars */
        while (psc_ops->raw_tx_rdy(port)) {
                psc_ops->write_char(port, xmit->buf[xmit->tail]);
                xmit->tail = (xmit->tail + 1) & (UART_XMIT_SIZE - 1);
                port->icount.tx++;
                if (uart_circ_empty(xmit))
                        break;
        }

        /* Wake up */
        if (uart_circ_chars_pending(xmit) < WAKEUP_CHARS)
                uart_write_wakeup(port);

        /* Maybe we're done after all */
        if (uart_circ_empty(xmit)) {
                mpc52xx_uart_stop_tx(port);
                return 0;
        }

        return 1;
}

static irqreturn_t
mpc52xx_uart_int(int irq, void *dev_id)
{
        struct uart_port *port = dev_id;
        unsigned long pass = ISR_PASS_LIMIT;
        unsigned int keepgoing;

        spin_lock(&port->lock);

        /* While we have stuff to do, we continue */
        do {
                /* If we don't find anything to do, we stop */
                keepgoing = 0;

                psc_ops->rx_clr_irq(port);
                if (psc_ops->rx_rdy(port))
                        keepgoing |= mpc52xx_uart_int_rx_chars(port);

                psc_ops->tx_clr_irq(port);
                if (psc_ops->tx_rdy(port))
                        keepgoing |= mpc52xx_uart_int_tx_chars(port);

                /* Limit number of iteration */
                if (!(--pass))
                        keepgoing = 0;

        } while (keepgoing);

        spin_unlock(&port->lock);

        return IRQ_HANDLED;
}


/* ======================================================================== */
/* Console ( if applicable )                                                */
/* ======================================================================== */

#ifdef CONFIG_SERIAL_MPC52xx_CONSOLE

static void __init
mpc52xx_console_get_options(struct uart_port *port,
                            int *baud, int *parity, int *bits, int *flow)
{
        struct mpc52xx_psc __iomem *psc = PSC(port);
        unsigned char mr1;

        pr_debug("mpc52xx_console_get_options(port=%p)\n", port);

        /* Read the mode registers */
        out_8(&psc->command, MPC52xx_PSC_SEL_MODE_REG_1);
        mr1 = in_8(&psc->mode);

        /* CT{U,L}R are write-only ! */
        *baud = CONFIG_SERIAL_MPC52xx_CONSOLE_BAUD;

        /* Parse them */
        switch (mr1 & MPC52xx_PSC_MODE_BITS_MASK) {
        case MPC52xx_PSC_MODE_5_BITS:
                *bits = 5;
                break;
        case MPC52xx_PSC_MODE_6_BITS:
                *bits = 6;
                break;
        case MPC52xx_PSC_MODE_7_BITS:
                *bits = 7;
                break;
        case MPC52xx_PSC_MODE_8_BITS:
        default:
                *bits = 8;
        }

        if (mr1 & MPC52xx_PSC_MODE_PARNONE)
                *parity = 'n';
        else
                *parity = mr1 & MPC52xx_PSC_MODE_PARODD ? 'o' : 'e';
}

static void
mpc52xx_console_write(struct console *co, const char *s, unsigned int count)
{
        struct uart_port *port = &mpc52xx_uart_ports[co->index];
        unsigned int i, j;

        /* Disable interrupts */
        psc_ops->cw_disable_ints(port);

        /* Wait the TX buffer to be empty */
        j = 5000000;    /* Maximum wait */
        while (!mpc52xx_uart_tx_empty(port) && --j)
                udelay(1);

        /* Write all the chars */
        for (i = 0; i < count; i++, s++) {
                /* Line return handling */
                if (*s == '\n')
                        psc_ops->write_char(port, '\r');

                /* Send the char */
                psc_ops->write_char(port, *s);

                /* Wait the TX buffer to be empty */
                j = 20000;      /* Maximum wait */
                while (!mpc52xx_uart_tx_empty(port) && --j)
                        udelay(1);
        }

        /* Restore interrupt state */
        psc_ops->cw_restore_ints(port);
}


static int __init
mpc52xx_console_setup(struct console *co, char *options)
{
        struct uart_port *port = &mpc52xx_uart_ports[co->index];
        struct device_node *np = mpc52xx_uart_nodes[co->index];
        unsigned int uartclk;
        struct resource res;
        int ret;

        int baud = CONFIG_SERIAL_MPC52xx_CONSOLE_BAUD;
        int bits = 8;
        int parity = 'n';
        int flow = 'n';

        pr_debug("mpc52xx_console_setup co=%p, co->index=%i, options=%s\n",
                 co, co->index, options);

        if ((co->index < 0) || (co->index > MPC52xx_PSC_MAXNUM)) {
                pr_debug("PSC%x out of range\n", co->index);
                return -EINVAL;
        }

        if (!np) {
                pr_debug("PSC%x not found in device tree\n", co->index);
                return -EINVAL;
        }

        pr_debug("Console on ttyPSC%x is %s\n",
                 co->index, mpc52xx_uart_nodes[co->index]->full_name);

        /* Fetch register locations */
        ret = of_address_to_resource(np, 0, &res);
        if (ret) {
                pr_debug("Could not get resources for PSC%x\n", co->index);
                return ret;
        }

        uartclk = psc_ops->getuartclk(np);
        if (uartclk == 0) {
                pr_debug("Could not find uart clock frequency!\n");
                return -EINVAL;
        }

        /* Basic port init. Needed since we use some uart_??? func before
         * real init for early access */
        spin_lock_init(&port->lock);
        port->uartclk = uartclk;
        port->ops       = &mpc52xx_uart_ops;
        port->mapbase = res.start;
        port->membase = ioremap(res.start, sizeof(struct mpc52xx_psc));
        port->irq = irq_of_parse_and_map(np, 0);

        if (port->membase == NULL)
                return -EINVAL;

        pr_debug("mpc52xx-psc uart at %p, mapped to %p, irq=%x, freq=%i\n",
                 (void *)port->mapbase, port->membase,
                 port->irq, port->uartclk);

        /* Setup the port parameters accoding to options */
        if (options)
                uart_parse_options(options, &baud, &parity, &bits, &flow);
        else
                mpc52xx_console_get_options(port, &baud, &parity, &bits, &flow);

        pr_debug("Setting console parameters: %i %i%c1 flow=%c\n",

                 baud, bits, parity, flow);

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


static struct uart_driver mpc52xx_uart_driver;

static struct console mpc52xx_console = {
        .name   = "ttyPSC",
        .write  = mpc52xx_console_write,
        .device = uart_console_device,
        .setup  = mpc52xx_console_setup,
        .flags  = CON_PRINTBUFFER,
        .index  = -1,   /* Specified on the cmdline (e.g. console=ttyPSC0) */
        .data   = &mpc52xx_uart_driver,
};


static int __init
mpc52xx_console_init(void)
{
        mpc52xx_uart_of_enumerate();
        register_console(&mpc52xx_console);
        return 0;
}

console_initcall(mpc52xx_console_init);

#define MPC52xx_PSC_CONSOLE &mpc52xx_console
#else
#define MPC52xx_PSC_CONSOLE NULL
#endif


/* ======================================================================== */
/* UART Driver                                                              */
/* ======================================================================== */

static struct uart_driver mpc52xx_uart_driver = {
        .driver_name    = "mpc52xx_psc_uart",
        .dev_name       = "ttyPSC",
        .major          = SERIAL_PSC_MAJOR,
        .minor          = SERIAL_PSC_MINOR,
        .nr             = MPC52xx_PSC_MAXNUM,
        .cons           = MPC52xx_PSC_CONSOLE,
};

/* ======================================================================== */
/* OF Platform Driver                                                       */
/* ======================================================================== */

static struct of_device_id mpc52xx_uart_of_match[] = {
#ifdef CONFIG_PPC_MPC52xx
        { .compatible = "fsl,mpc5200-psc-uart", .data = &mpc52xx_psc_ops, },
        /* binding used by old lite5200 device trees: */
        { .compatible = "mpc5200-psc-uart", .data = &mpc52xx_psc_ops, },
        /* binding used by efika: */
        { .compatible = "mpc5200-serial", .data = &mpc52xx_psc_ops, },
#endif
#ifdef CONFIG_PPC_MPC512x
        { .compatible = "fsl,mpc5121-psc-uart", .data = &mpc512x_psc_ops, },
#endif
        {},
};

static int __devinit
mpc52xx_uart_of_probe(struct of_device *op, const struct of_device_id *match)
{
        int idx = -1;
        unsigned int uartclk;
        struct uart_port *port = NULL;
        struct resource res;
        int ret;

        dev_dbg(&op->dev, "mpc52xx_uart_probe(op=%p, match=%p)\n", op, match);

        /* Check validity & presence */
        for (idx = 0; idx < MPC52xx_PSC_MAXNUM; idx++)
                if (mpc52xx_uart_nodes[idx] == op->node)
                        break;
        if (idx >= MPC52xx_PSC_MAXNUM)
                return -EINVAL;
        pr_debug("Found %s assigned to ttyPSC%x\n",
                 mpc52xx_uart_nodes[idx]->full_name, idx);

        uartclk = psc_ops->getuartclk(op->node);
        if (uartclk == 0) {
                dev_dbg(&op->dev, "Could not find uart clock frequency!\n");
                return -EINVAL;
        }

        /* Init the port structure */
        port = &mpc52xx_uart_ports[idx];

        spin_lock_init(&port->lock);
        port->uartclk = uartclk;
        port->fifosize  = 512;
        port->iotype    = UPIO_MEM;
        port->flags     = UPF_BOOT_AUTOCONF |
                          (uart_console(port) ? 0 : UPF_IOREMAP);
        port->line      = idx;
        port->ops       = &mpc52xx_uart_ops;
        port->dev       = &op->dev;

        /* Search for IRQ and mapbase */
        ret = of_address_to_resource(op->node, 0, &res);
        if (ret)
                return ret;

        port->mapbase = res.start;
        port->irq = irq_of_parse_and_map(op->node, 0);

        dev_dbg(&op->dev, "mpc52xx-psc uart at %p, irq=%x, freq=%i\n",
                (void *)port->mapbase, port->irq, port->uartclk);

        if ((port->irq == NO_IRQ) || !port->mapbase) {
                printk(KERN_ERR "Could not allocate resources for PSC\n");
                return -EINVAL;
        }

        /* Add the port to the uart sub-system */
        ret = uart_add_one_port(&mpc52xx_uart_driver, port);
        if (!ret)
                dev_set_drvdata(&op->dev, (void *)port);

        return ret;
}

static int
mpc52xx_uart_of_remove(struct of_device *op)
{
        struct uart_port *port = dev_get_drvdata(&op->dev);
        dev_set_drvdata(&op->dev, NULL);

        if (port) {
                uart_remove_one_port(&mpc52xx_uart_driver, port);
                irq_dispose_mapping(port->irq);
        }

        return 0;
}

#ifdef CONFIG_PM
static int
mpc52xx_uart_of_suspend(struct of_device *op, pm_message_t state)
{
        struct uart_port *port = (struct uart_port *) dev_get_drvdata(&op->dev);

        if (port)
                uart_suspend_port(&mpc52xx_uart_driver, port);

        return 0;
}

static int
mpc52xx_uart_of_resume(struct of_device *op)
{
        struct uart_port *port = (struct uart_port *) dev_get_drvdata(&op->dev);

        if (port)
                uart_resume_port(&mpc52xx_uart_driver, port);

        return 0;
}
#endif

static void
mpc52xx_uart_of_assign(struct device_node *np, int idx)
{
        int free_idx = -1;
        int i;

        /* Find the first free node */
        for (i = 0; i < MPC52xx_PSC_MAXNUM; i++) {
                if (mpc52xx_uart_nodes[i] == NULL) {
                        free_idx = i;
                        break;
                }
        }

        if ((idx < 0) || (idx >= MPC52xx_PSC_MAXNUM))
                idx = free_idx;

        if (idx < 0)
                return; /* No free slot; abort */

        of_node_get(np);
        /* If the slot is already occupied, then swap slots */
        if (mpc52xx_uart_nodes[idx] && (free_idx != -1))
                mpc52xx_uart_nodes[free_idx] = mpc52xx_uart_nodes[idx];
        mpc52xx_uart_nodes[idx] = np;
}

static void
mpc52xx_uart_of_enumerate(void)
{
        static int enum_done;
        struct device_node *np;
        const unsigned int *devno;
        const struct  of_device_id *match;
        int i;

        if (enum_done)
                return;

        for_each_node_by_type(np, "serial") {
                match = of_match_node(mpc52xx_uart_of_match, np);
                if (!match)
                        continue;

                psc_ops = match->data;

                /* Is a particular device number requested? */
                devno = of_get_property(np, "port-number", NULL);
                mpc52xx_uart_of_assign(np, devno ? *devno : -1);
        }

        enum_done = 1;

        for (i = 0; i < MPC52xx_PSC_MAXNUM; i++) {
                if (mpc52xx_uart_nodes[i])
                        pr_debug("%s assigned to ttyPSC%x\n",
                                 mpc52xx_uart_nodes[i]->full_name, i);
        }
}

MODULE_DEVICE_TABLE(of, mpc52xx_uart_of_match);

static struct of_platform_driver mpc52xx_uart_of_driver = {
        .match_table    = mpc52xx_uart_of_match,
        .probe          = mpc52xx_uart_of_probe,
        .remove         = mpc52xx_uart_of_remove,
#ifdef CONFIG_PM
        .suspend        = mpc52xx_uart_of_suspend,
        .resume         = mpc52xx_uart_of_resume,
#endif
        .driver         = {
                .name   = "mpc52xx-psc-uart",
        },
};


/* ======================================================================== */
/* Module                                                                   */
/* ======================================================================== */

static int __init
mpc52xx_uart_init(void)
{
        int ret;

        printk(KERN_INFO "Serial: MPC52xx PSC UART driver\n");

        ret = uart_register_driver(&mpc52xx_uart_driver);
        if (ret) {
                printk(KERN_ERR "%s: uart_register_driver failed (%i)\n",
                       __FILE__, ret);
                return ret;
        }

        mpc52xx_uart_of_enumerate();

        ret = of_register_platform_driver(&mpc52xx_uart_of_driver);
        if (ret) {
                printk(KERN_ERR "%s: of_register_platform_driver failed (%i)\n",
                       __FILE__, ret);
                uart_unregister_driver(&mpc52xx_uart_driver);
                return ret;
        }

        return 0;
}

static void __exit
mpc52xx_uart_exit(void)
{
        of_unregister_platform_driver(&mpc52xx_uart_of_driver);
        uart_unregister_driver(&mpc52xx_uart_driver);
}


module_init(mpc52xx_uart_init);
module_exit(mpc52xx_uart_exit);

MODULE_AUTHOR("Sylvain Munaut <tnt@246tNt.com>");
MODULE_DESCRIPTION("Freescale MPC52xx PSC UART");
MODULE_LICENSE("GPL");