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[linux-2.6.19-moxart.git] / drivers / serial / NIOSserial.c

/*--------------------------------------------------------------------
 *
 * drivers\serial\NIOSserial.c
 *
 * Serial port driver for builtin NIOS UART.
 *
 * Copyright (C) 1995       David S. Miller    <davem@caip.rutgers.edu>
 * Copyright (C) 1998       Kenneth Albanowski <kjahds@kjahds.com>
 * Copyright (C) 1998-2000  D. Jeff Dionne     <jeff@lineo.ca>
 * Copyright (C) 1999       Vladimir Gurevich  <vgurevic@cisco.com>
 * Copyright (C) 2001       Vic Phillips       <vic@microtronix.com>
 * Copyright (C) 2001       Wentao Xu          <wentao@microtronix.com>
 * Copyright (C) 2004   Microtronix Datacom Ltd
 *
 * 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.
 *
 *
 * Jan/20/2004          dgt         NiosII
 *
 ---------------------------------------------------------------------*/


#include <linux/module.h>
#include <linux/errno.h>
#include <linux/signal.h>
#include <linux/sched.h>
#include <linux/timer.h>
#include <linux/interrupt.h>
#include <linux/tty.h>
#include <linux/tty_flip.h>
#include <linux/major.h>
#include <linux/string.h>
#include <linux/fcntl.h>
#include <linux/mm.h>
#include <linux/kernel.h>
#include <linux/console.h>
#include <linux/reboot.h>
#include <linux/keyboard.h>
#include <linux/init.h>
#include <linux/smp_lock.h>
#include <linux/serial.h>
#include <linux/irq.h>

#include <asm/io.h>
#include <asm/system.h>
#include <asm/segment.h>
#include <asm/bitops.h>
#include <asm/delay.h>
#include <asm/uaccess.h>

#include "NIOSserial.h"

#define DEBUG 1

//struct tty_struct NIOS_ttys;
//struct NIOS_serial *NIOS_consinfo = 0;

#ifdef CONFIG_CONSOLE
extern wait_queue_head_t keypress_wait;
#endif

struct tty_driver *serial_driver;

/* serial subtype definitions */
#define SERIAL_TYPE_NORMAL      1

/* number of characters left in xmit buffer before we ask for more */
#define WAKEUP_CHARS 256

/* Debugging... DEBUG_INTR is bad to use when one of the zs
 * lines is your console ;(
 */
#undef SERIAL_DEBUG_INTR
#undef SERIAL_DEBUG_OPEN
#undef SERIAL_DEBUG_FLOW

#define RS_ISR_PASS_LIMIT 256

#define _INLINE_ inline

static void change_speed(struct NIOS_serial *info);

/*
 *      Configuration table, UARTs to look for at startup.
 */
static struct NIOS_serial nios_soft[] = {
//      { 0,0,1,0,0,0,0, (nasys_printf_uart), (nasys_printf_uart_irq) }, /* ttyS0 */
        { 0,0,1,0,0,0,0, (int) (na_uart0), (na_uart0_irq) },            /* ttyS0 */
#ifdef na_uart1
//      { 0,0,0,0,0,0,0, (nasys_gdb_uart), (nasys_gdb_uart_irq) },      /* ttyS1 */
        { 0,0,0,0,0,0,0, (int) (na_uart1), (na_uart1_irq) },            /* ttyS1 */
#endif
#ifdef na_uart2
        { 0,0,0,0,0,0,0, (int) (na_uart2), (na_uart2_irq) },            /* ttyS2 */
#endif
#ifdef na_uart3
        { 0,0,0,0,0,0,0, (int) (na_uart3), (na_uart3_irq) },            /* ttyS3 */
#endif
};

#define NR_PORTS        (sizeof(nios_soft) / sizeof(struct NIOS_serial))


/*
 * tmp_buf is used as a temporary buffer by serial_write.  We need to
 * lock it in case the memcpy_fromfs blocks while swapping in a page,
 * and some other program tries to do a serial write at the same time.
 * Since the lock will only come under contention when the system is
 * swapping and available memory is low, it makes sense to share one
 * buffer across all the serial ports, since it significantly saves
 * memory if large numbers of serial ports are open.
 */
static unsigned char tmp_buf[SERIAL_XMIT_SIZE]; /* This is cheating */
DECLARE_MUTEX(tmp_buf_sem);

static inline int serial_paranoia_check(struct NIOS_serial *info,
                                        char *name, const char *routine)
{
#ifdef SERIAL_PARANOIA_CHECK
        static const char *badmagic =
                "Warning: bad magic number for serial struct %s in %s\n";
        static const char *badinfo =
                "Warning: null nios_serial for %s in %s\n";

        if (!info) {
                printk(badinfo, name, routine);
                return 1;
        }
        if (info->magic != SERIAL_MAGIC) {
                printk(badmagic, name, routine);
                return 1;
        }
#endif
        return 0;
}

/*
 * This is used to figure out the divisor speeds and the timeouts
 */
static int baud_table[] = {
        0, 50, 75, 110, 134, 150, 200, 300, 600, 1200, 1800, 2400, 4800,
        9600, 19200, 38400, 57600, 115200, 0 };

/* Sets or clears DTR/RTS on the requested line */
static inline void NIOS_rtsdtr(struct NIOS_serial *ss, int set)
{
        if (set) {
                /* set the RTS/CTS line */
        } else {
                /* clear it */
        }
        return;
}

/* Utility routines */
static inline int get_baud(struct NIOS_serial *ss)
{
        return 0;       /* not implemented yet */
}

/*
 * ------------------------------------------------------------
 * rs_stop() and rs_start()
 *
 * This routines are called before setting or resetting tty->stopped.
 * They enable or disable transmitter interrupts, as necessary.
 * ------------------------------------------------------------
 */
static void rs_stop(struct tty_struct *tty)
{
        struct NIOS_serial *info = (struct NIOS_serial *)tty->driver_data;
        np_uart *       uart= (np_uart *)(info->port);
        unsigned long flags;

        if (serial_paranoia_check(info, tty->name, "rs_stop"))
                return;

        local_irq_save(flags);
        uart->np_uartcontrol &= ~np_uartcontrol_itrdy_mask;
        local_irq_restore(flags);
}

static void rs_put_char(char ch, struct NIOS_serial *info)
{
        int flags, loops = 0;
        np_uart *       uart= (np_uart *)(info->port);

        local_irq_save(flags);

        while (!(uart->np_uartstatus & np_uartstatus_trdy_mask) && (loops < 100000)) {
                loops++;
        }

        uart->np_uarttxdata = ch;
        local_irq_restore(flags);
}

static void rs_start(struct tty_struct *tty)
{
        struct NIOS_serial *info = (struct NIOS_serial *)tty->driver_data;
        unsigned long flags;
        np_uart *       uart= (np_uart *)(info->port);

        if (serial_paranoia_check(info, tty->name, "rs_start"))
                return;

        local_irq_save(flags);
        if (info->xmit_cnt && info->xmit_buf && !(uart->np_uartcontrol & np_uartcontrol_itrdy_mask)) {
#ifdef USE_INTS
                uart->np_uartcontrol &= np_uartcontrol_itrdy_mask;
#endif
        }
        local_irq_restore(flags);
}

/* Drop into either the boot monitor or gdb upon receiving a break
 * from keyboard/console input.
 */
#ifdef CONFIG_MAGIC_SYSRQ
static void batten_down_hatches(void)
{
        /* Drop into the debugger */
  //    nios_gdb_breakpoint();
}
#endif // CONFIG_MAGIC_SYSRQ

static _INLINE_ void status_handle(struct NIOS_serial *info, unsigned short status)
{
        return;
}

static _INLINE_ void receive_chars(struct NIOS_serial *info, unsigned short rx)
{
        struct tty_struct *tty = info->tty;
        unsigned char ch, flag;
        np_uart *       uart= (np_uart *)(info->port);

        /*
         * This do { } while() loop will get ALL chars out of Rx FIFO
         */
        do {
                ch = uart->np_uartrxdata;

                if(info->is_cons) {
#ifdef CONFIG_MAGIC_SYSRQ
                        if(rx & np_uartstatus_brk_mask) {
                                batten_down_hatches();
                                return;
                        } else if (ch == 0x10) { /* ^P */
                                show_state();
                                show_mem();
                                return;
#ifdef DEBUG
                        } else if (ch == 0x02) { /* ^B */
                                batten_down_hatches();
                                return;
#endif
                        }
#endif /* CONFIG_MAGIC_SYSRQ */
                        /* It is a 'keyboard interrupt' ;-) */
#ifdef CONFIG_CONSOLE
                        wake_up(&keypress_wait);
#endif
                }

                if(!tty)
                        goto clear_and_exit;

                flag = TTY_NORMAL;

                if(rx & np_uartstatus_pe_mask) {
                        flag = TTY_PARITY;
                        status_handle(info, rx);
                } else if(rx & np_uartstatus_roe_mask) {
                        flag = TTY_OVERRUN;
                        status_handle(info, rx);
                } else if(rx & np_uartstatus_fe_mask) {
                        flag = TTY_FRAME;
                        status_handle(info, rx);
                } else if(rx & np_uartstatus_brk_mask) {
                        flag = TTY_BREAK;
                        status_handle(info, rx);
                }
                tty_insert_flip_char(tty, ch, flag);

        } while((rx = uart->np_uartstatus) & np_uartstatus_rrdy_mask);

        tty_schedule_flip(tty);

clear_and_exit:
        return;
}

static _INLINE_ void transmit_chars(struct NIOS_serial *info)
{
        struct tty_struct       *tty = info->tty;
        np_uart *       uart= (np_uart *)(info->port);
        if (info->x_char) {
                /* Send next char */
                uart->np_uarttxdata = info->x_char;
                info->x_char = 0;
                goto clear_and_return;
        }

        if((info->xmit_cnt <= 0) || info->tty->stopped) {
                /* That's peculiar... TX ints off */
                uart->np_uartcontrol &= ~np_uartcontrol_itrdy_mask;
                goto clear_and_return;
        }

        /* Send char */
        uart->np_uarttxdata = info->xmit_buf[info->xmit_tail++];
        info->xmit_tail = info->xmit_tail & (SERIAL_XMIT_SIZE-1);
        info->xmit_cnt--;

        if (info->xmit_cnt < WAKEUP_CHARS)
                schedule_work(&info->tqueue);

        if(info->xmit_cnt <= 0) {
                /* All done for now... TX ints off */
                uart->np_uartcontrol &= ~np_uartcontrol_itrdy_mask;
                wake_up_interruptible(&tty->write_wait);
                goto clear_and_return;
        }

clear_and_return:
        /* Clear interrupt (should be auto)*/
        return;
}

/*
 * This is the serial driver's generic interrupt routine
 */
irqreturn_t rs_interrupt(int irq, void *dev_id)
{
        struct NIOS_serial * info = (struct NIOS_serial *) dev_id;
        np_uart *       uart= (np_uart *)(info->port);
        unsigned short stat = uart->np_uartstatus;
        uart->np_uartstatus = 0;                /* clear any error status */

        if (stat & np_uartstatus_rrdy_mask) receive_chars(info, stat);
        if (stat & np_uartstatus_trdy_mask) transmit_chars(info);
        return IRQ_HANDLED;
}

static void do_softint(void *private)
{
        struct NIOS_serial      *info = (struct NIOS_serial *) private;
        struct tty_struct       *tty;

        tty = info->tty;
        if (!tty)
                return;

}

/*
 * This routine is called from the scheduler tqueue when the interrupt
 * routine has signalled that a hangup has occurred.  The path of
 * hangup processing is:
 *
 *      serial interrupt routine -> (scheduler tqueue) ->
 *      do_serial_hangup() -> tty->hangup() -> rs_hangup()
 *
 */
static void do_serial_hangup(void *private_)
{
        struct NIOS_serial      *info = (struct NIOS_serial *) private_;
        struct tty_struct       *tty;

        tty = info->tty;
        if (!tty)
                return;

        tty_hangup(tty);
}



static int startup(struct NIOS_serial * info)
{
        unsigned long flags;
        np_uart *       uart= (np_uart *)(info->port);

        if (info->flags & S_INITIALIZED)
                return 0;

        if (!info->xmit_buf) {
                info->xmit_buf = (unsigned char *) __get_free_page(GFP_KERNEL);
                if (!info->xmit_buf)
                        return -ENOMEM;
        }

        local_irq_save(flags);

        /*
         * Clear the FIFO buffers and disable them
         * (they will be reenabled in change_speed())
         */

        change_speed(info);

        info->xmit_fifo_size = 1;
        uart->np_uartcontrol = np_uartcontrol_itrdy_mask
                             | np_uartcontrol_irrdy_mask
                             | np_uartcontrol_ibrk_mask;
        uart->np_uartrxdata;

        if (info->tty)
                clear_bit(TTY_IO_ERROR, &info->tty->flags);
        info->xmit_cnt = info->xmit_head = info->xmit_tail = 0;

        info->flags |= S_INITIALIZED;
        local_irq_restore(flags);
        return 0;
}

/*
 * This routine will shutdown a serial port; interrupts are disabled, and
 * DTR is dropped if the hangup on close termio flag is on.
 */
static void shutdown(struct NIOS_serial * info)
{
        unsigned long   flags;
        np_uart *       uart= (np_uart *)(info->port);

        uart->np_uartcontrol = 0; /* All off! */
        if (!(info->flags & S_INITIALIZED))
                return;

        local_irq_save(flags);  /* Disable interrupts */

        if (info->xmit_buf) {
                free_page((unsigned long) info->xmit_buf);
                info->xmit_buf = 0;
        }

        if (info->tty)
                set_bit(TTY_IO_ERROR, &info->tty->flags);

        info->flags &= ~S_INITIALIZED;
        local_irq_restore(flags);
}

/*
 * This routine is called to set the UART divisor registers to match
 * the specified baud rate for a serial port.
 */
static void change_speed(struct NIOS_serial *info)
{
#if 1           /* NIOS usually has a fixed speed */

//      unsigned long ustcnt;
        unsigned cflag;
        unsigned divisor;
        int     i;
        np_uart *       uart= (np_uart *)(info->port);

        if (!info->tty || !info->tty->termios)
                return;
        cflag = info->tty->termios->c_cflag;

//      ustcnt = uart->np_uartcontrol;
//      uart->np_uartcontrol = ustcnt & ~UCTRL_TE;

        i = cflag & CBAUD;
        if (i & CBAUDEX) {
                i = (i & ~CBAUDEX) + B38400;
        }

        divisor = (unsigned)(((unsigned)nasys_clock_freq *1.0 / baud_table[i]) + 1) -1;
        uart->np_uartdivisor = divisor;
        if (uart->np_uartdivisor == divisor)
                info->baud = baud_table[i];

//      ustcnt &= ~(UCTRL_PE | UCTRL_PS);
//      if ((cflag & CSIZE) == CS8)
//              ustcnt |= USTCNT_8_7;
//      if (cflag & CSTOPB)
//              ustcnt |= USTCNT_STOP;
//      if (cflag & PARENB)
//              ustcnt |= UCTRL_PE;
//      if (!(cflag & PARODD))
//              ustcnt |= UCTRL_PS;
//      if (cflag & CRTSCTS) {
//              ustcnt |= UCTRL_FL;
//      } else {
//              ustcnt &= ~UCTRL_FL;
//      }
//      ustcnt |= UCTRL_TE;
//      uart->np_uartcontrol = ustcnt;

#endif
}

/*
 * Fair output driver allows a process to speak.
 */
#if 0
static void rs_fair_output(void)
{
        int left;               /* Output no more than that */
        unsigned long flags;
        struct NIOS_serial *info = &nios_soft;
        char c;

        if (info == 0) return;
        if (info->xmit_buf == 0) return;

        local_irq_save(flags);
        left = info->xmit_cnt;
        while (left != 0) {
                c = info->xmit_buf[info->xmit_tail];
                info->xmit_tail = (info->xmit_tail+1) & (SERIAL_XMIT_SIZE-1);
                info->xmit_cnt--;
                local_irq_restore(flags);

                rs_put_char(c, info);

                local_irq_save(flags);
                left = min(info->xmit_cnt, left-1);
        }

        /* Last character is being transmitted now (hopefully). */
        udelay(5);

        local_irq_restore(flags);
        return;
}
#endif

/*
 * console_print_NIOS is registered for printk.
 */
void console_print_NIOS(const char *p)
{
        char c;

        while((c=*(p++)) != 0) {
                if(c == '\n')
                        rs_put_char('\r', nios_soft);
                rs_put_char(c, nios_soft);
        }

        /* Comment this if you want to have a strict interrupt-driven output */
        /* rs_fair_output(); */

        return;
}

static void rs_set_ldisc(struct tty_struct *tty)
{
        struct NIOS_serial *info = (struct NIOS_serial *)tty->driver_data;

        if (serial_paranoia_check(info, tty->name, "rs_set_ldisc"))
                return;

        info->is_cons = (tty->termios->c_line == N_TTY);

        printk("ttyS%d console mode %s\n", info->line, info->is_cons ? "on" : "off");
}

static void rs_flush_chars(struct tty_struct *tty)
{
        struct NIOS_serial *info = (struct NIOS_serial *)tty->driver_data;
        unsigned long flags;
        np_uart *       uart= (np_uart *)(info->port);

        if (serial_paranoia_check(info, tty->name, "rs_flush_chars"))
                return;

        local_irq_save(flags);

        if (info->xmit_cnt <= 0 || tty->stopped || tty->hw_stopped ||
            !info->xmit_buf)
                goto flush_exit;

        /* Enable transmitter */

        uart->np_uartcontrol |= np_uartcontrol_itrdy_mask;

        if (uart->np_uartstatus & np_uartstatus_trdy_mask) {
                /* Send char */
                uart->np_uarttxdata = info->xmit_buf[info->xmit_tail++];
                info->xmit_tail = info->xmit_tail & (SERIAL_XMIT_SIZE-1);
                info->xmit_cnt--;
        }

flush_exit:
        local_irq_restore(flags);
}

extern void console_printn(const char * b, int count);

static int rs_write(struct tty_struct * tty,
                    const unsigned char *buf, int count)
{
        int     c, total = 0;
        struct NIOS_serial *info = (struct NIOS_serial *)tty->driver_data;
        unsigned long flags;
        np_uart *       uart= (np_uart *)(info->port);

        if (serial_paranoia_check(info, tty->name, "rs_write"))
                return 0;

        if (!tty || !info->xmit_buf)
                return 0;

        local_save_flags(flags);
        while (1) {
                local_irq_disable();
                c = min_t(int, count, min(SERIAL_XMIT_SIZE - info->xmit_cnt - 1,
                                   SERIAL_XMIT_SIZE - info->xmit_head));
                if (c <= 0)
                        break;

                memcpy(info->xmit_buf + info->xmit_head, buf, c);
                info->xmit_head = (info->xmit_head + c) & (SERIAL_XMIT_SIZE-1);
                info->xmit_cnt += c;
                local_irq_restore(flags);
                buf += c;
                count -= c;
                total += c;

        }

        if (info->xmit_cnt && !tty->stopped && !tty->hw_stopped) {
                /* Enable transmitter */
                local_irq_disable();

                uart->np_uartcontrol |= np_uartcontrol_itrdy_mask;

                if (uart->np_uartstatus & np_uartstatus_trdy_mask) {
                        uart->np_uarttxdata = info->xmit_buf[info->xmit_tail++];
                        info->xmit_tail = info->xmit_tail & (SERIAL_XMIT_SIZE-1);
                        info->xmit_cnt--;
                }

                local_irq_restore(flags);
        }
        local_irq_restore(flags);
        return total;
}

static int rs_write_room(struct tty_struct *tty)
{
        struct NIOS_serial *info = (struct NIOS_serial *)tty->driver_data;
        int     ret;

        if (serial_paranoia_check(info, tty->name, "rs_write_room"))
                return 0;
        ret = SERIAL_XMIT_SIZE - info->xmit_cnt - 1;
        if (ret < 0)
                ret = 0;
        return ret;
}

static int rs_chars_in_buffer(struct tty_struct *tty)
{
        struct NIOS_serial *info = (struct NIOS_serial *)tty->driver_data;

        if (serial_paranoia_check(info, tty->name, "rs_chars_in_buffer"))
                return 0;
        return info->xmit_cnt;
}

static void rs_flush_buffer(struct tty_struct *tty)
{
        struct NIOS_serial *info = (struct NIOS_serial *)tty->driver_data;

        if (serial_paranoia_check(info, tty->name, "rs_flush_buffer"))
                return;
        local_irq_disable();
        info->xmit_cnt = info->xmit_head = info->xmit_tail = 0;
        local_irq_enable();
        wake_up_interruptible(&tty->write_wait);
        if ((tty->flags & (1 << TTY_DO_WRITE_WAKEUP)) &&
            tty->ldisc.write_wakeup)
                (tty->ldisc.write_wakeup)(tty);
}

/*
 * ------------------------------------------------------------
 * rs_throttle()
 *
 * This routine is called by the upper-layer tty layer to signal that
 * incoming characters should be throttled.
 * ------------------------------------------------------------
 */
static void rs_throttle(struct tty_struct * tty)
{
        struct NIOS_serial *info = (struct NIOS_serial *)tty->driver_data;

        if (serial_paranoia_check(info, tty->name, "rs_throttle"))
                return;

        if (I_IXOFF(tty))
                info->x_char = STOP_CHAR(tty);

        /* Turn off RTS line (do this atomic) */
}

static void rs_unthrottle(struct tty_struct * tty)
{
        struct NIOS_serial *info = (struct NIOS_serial *)tty->driver_data;

        if (serial_paranoia_check(info, tty->name, "rs_unthrottle"))
                return;

        if (I_IXOFF(tty)) {
                if (info->x_char)
                        info->x_char = 0;
                else
                        info->x_char = START_CHAR(tty);
        }

        /* Assert RTS line (do this atomic) */
}

/*
 * ------------------------------------------------------------
 * rs_ioctl() and friends
 * ------------------------------------------------------------
 */

static int get_serial_info(struct NIOS_serial * info,
                           struct serial_struct * retinfo)
{
        struct serial_struct tmp;

        if (!retinfo)
                return -EFAULT;
        memset(&tmp, 0, sizeof(tmp));
        tmp.type = info->type;
        tmp.line = info->line;
        tmp.port = info->port;
        tmp.irq = info->irq;
        tmp.flags = info->flags;
        tmp.baud_base = info->baud_base;
        tmp.close_delay = info->close_delay;
        tmp.closing_wait = info->closing_wait;
        tmp.custom_divisor = info->custom_divisor;
        copy_to_user(retinfo,&tmp,sizeof(*retinfo));
        return 0;
}

static int set_serial_info(struct NIOS_serial * info,
                           struct serial_struct * new_info)
{
        struct serial_struct new_serial;
        struct NIOS_serial old_info;
        int                     retval = 0;

        if (!new_info)
                return -EFAULT;
        copy_from_user(&new_serial,new_info,sizeof(new_serial));
        old_info = *info;

        if (!capable(CAP_SYS_ADMIN)) {
                if ((new_serial.baud_base != info->baud_base) ||
                    (new_serial.type != info->type) ||
                    (new_serial.close_delay != info->close_delay) ||
                    ((new_serial.flags & ~S_USR_MASK) !=
                     (info->flags & ~S_USR_MASK)))
                        return -EPERM;
                info->flags = ((info->flags & ~S_USR_MASK) |
                               (new_serial.flags & S_USR_MASK));
                info->custom_divisor = new_serial.custom_divisor;
                goto check_and_exit;
        }

        if (info->count > 1)
                return -EBUSY;

        /*
         * OK, past this point, all the error checking has been done.
         * At this point, we start making changes.....
         */

        info->baud_base = new_serial.baud_base;
        info->flags = ((info->flags & ~S_FLAGS) |
                        (new_serial.flags & S_FLAGS));
        info->type = new_serial.type;
        info->close_delay = new_serial.close_delay;
        info->closing_wait = new_serial.closing_wait;

check_and_exit:
        retval = startup(info);
        return retval;
}

/*
 * get_lsr_info - get line status register info
 *
 * Purpose: Let user call ioctl() to get info when the UART physically
 *          is emptied.  On bus types like RS485, the transmitter must
 *          release the bus after transmitting. This must be done when
 *          the transmit shift register is empty, not be done when the
 *          transmit holding register is empty.  This functionality
 *          allows an RS485 driver to be written in user space.
 */
static int get_lsr_info(struct NIOS_serial * info, unsigned int *value)
{
        unsigned char status;

        status = 0;
        put_user(status,value);
        return 0;
}

/*
 * This routine sends a break character out the serial port.
 */
static void send_break( struct NIOS_serial * info, int duration)
{
}

static int rs_ioctl(struct tty_struct *tty, struct file * file,
                    unsigned int cmd, unsigned long arg)
{
        int error;
        struct NIOS_serial * info = (struct NIOS_serial *)tty->driver_data;
        int retval;

        if (serial_paranoia_check(info, tty->name, "rs_ioctl"))
                return -ENODEV;

        if ((cmd != TIOCGSERIAL) && (cmd != TIOCSSERIAL) &&
            (cmd != TIOCSERCONFIG) && (cmd != TIOCSERGWILD)  &&
            (cmd != TIOCSERSWILD) && (cmd != TIOCSERGSTRUCT)) {
                if (tty->flags & (1 << TTY_IO_ERROR))
                    return -EIO;
        }

        switch (cmd) {
                case TCSBRK:    /* SVID version: non-zero arg --> no break */
                        retval = tty_check_change(tty);
                        if (retval)
                                return retval;
                        tty_wait_until_sent(tty, 0);
                        if (!arg)
                                send_break(info, HZ/4); /* 1/4 second */
                        return 0;
                case TCSBRKP:   /* support for POSIX tcsendbreak() */
                        retval = tty_check_change(tty);
                        if (retval)
                                return retval;
                        tty_wait_until_sent(tty, 0);
                        send_break(info, arg ? arg*(HZ/10) : HZ/4);
                        return 0;
                case TIOCGSOFTCAR:
                        error = put_user(C_CLOCAL(tty) ? 1 : 0,
                                    (unsigned long *) arg);
                        if (error)
                                return error;
                        return 0;
                case TIOCSSOFTCAR:
                        get_user(arg, (unsigned long *) arg);
                        tty->termios->c_cflag =
                                ((tty->termios->c_cflag & ~CLOCAL) |
                                 (arg ? CLOCAL : 0));
                        return 0;
                case TIOCGSERIAL:
                        error = verify_area(VERIFY_WRITE, (void *) arg,
                                                sizeof(struct serial_struct));
                        if (error)
                                return error;
                        return get_serial_info(info,
                                               (struct serial_struct *) arg);
                case TIOCSSERIAL:
                        return set_serial_info(info,
                                               (struct serial_struct *) arg);
                case TIOCSERGETLSR: /* Get line status register */
                        error = verify_area(VERIFY_WRITE, (void *) arg,
                                sizeof(unsigned int));
                        if (error)
                                return error;
                        else
                            return get_lsr_info(info, (unsigned int *) arg);

                case TIOCSERGSTRUCT:
                        error = verify_area(VERIFY_WRITE, (void *) arg,
                                                sizeof(struct NIOS_serial));
                        if (error)
                                return error;
                        copy_to_user((struct NIOS_serial *) arg,
                                    info, sizeof(struct NIOS_serial));
                        return 0;

                default:
                        return -ENOIOCTLCMD;
                }
        return 0;
}

static void rs_set_termios(struct tty_struct *tty, struct termios *old_termios)
{
        struct NIOS_serial *info = (struct NIOS_serial *)tty->driver_data;
        int     oldbaud = info->baud;

        if (tty->termios->c_cflag == old_termios->c_cflag)
                return;

        change_speed(info);

        if (info->baud == oldbaud) /* can not change */
                tty->termios->c_cflag = old_termios->c_cflag;
        else    /* only speed can be changed */
                tty->termios->c_cflag = (tty->termios->c_cflag & CBAUD) | CS8 | CREAD | HUPCL | CLOCAL;
#if 0
        if ((old_termios->c_cflag & CRTSCTS) &&
            !(tty->termios->c_cflag & CRTSCTS)) {
                tty->hw_stopped = 0;
                rs_start(tty);
        }
#endif
}

/*
 * ------------------------------------------------------------
 * rs_close()
 *
 * This routine is called when the serial port gets closed.  First, we
 * wait for the last remaining data to be sent.  Then, we unlink its
 * S structure from the interrupt chain if necessary, and we free
 * that IRQ if nothing is left in the chain.
 * ------------------------------------------------------------
 */
static void rs_close(struct tty_struct *tty, struct file * filp)
{
        struct NIOS_serial * info = (struct NIOS_serial *)tty->driver_data;
        unsigned long flags;
        np_uart *       uart= (np_uart *)(info->port);

        if (!info || serial_paranoia_check(info, tty->name, "rs_close"))
                return;

        local_irq_save(flags);

        if (tty_hung_up_p(filp)) {
                local_irq_restore(flags);
                return;
        }

        if ((tty->count == 1) && (info->count != 1)) {
                /*
                 * Uh, oh.  tty->count is 1, which means that the tty
                 * structure will be freed.  Info->count should always
                 * be one in these conditions.  If it's greater than
                 * one, we've got real problems, since it means the
                 * serial port won't be shutdown.
                 */
                printk("rs_close: bad serial port count; tty->count is 1, "
                       "info->count is %d\n", info->count);
                info->count = 1;
        }
        if (--info->count < 0) {
                printk("rs_close: bad serial port count for ttyS%d: %d\n",
                       info->line, info->count);
                info->count = 0;
        }
        if (info->count) {
                local_irq_restore(flags);
                return;
        }
        info->flags |= S_CLOSING;
        /*
         * Now we wait for the transmit buffer to clear; and we notify
         * the line discipline to only process XON/XOFF characters.
         */
        tty->closing = 1;
        if (info->closing_wait != S_CLOSING_WAIT_NONE)
                tty_wait_until_sent(tty, info->closing_wait);
        /*
         * At this point we stop accepting input.  To do this, we
         * disable the receive line status interrupts, and tell the
         * interrupt driver to stop checking the data ready bit in the
         * line status register.
         */

        uart->np_uartcontrol &= ~(np_uartcontrol_irrdy_mask);

        shutdown(info);
        if (tty->driver->flush_buffer)
                tty->driver->flush_buffer(tty);
        if (tty->ldisc.flush_buffer)
                tty->ldisc.flush_buffer(tty);
        tty->closing = 0;
        info->event = 0;
        info->tty = 0;
#if 0
        if (tty->ldisc.num != ldiscs[N_TTY].num) {
                if (tty->ldisc.close)
                        (tty->ldisc.close)(tty);
                tty->ldisc = ldiscs[N_TTY];
                tty->termios->c_line = N_TTY;
                if (tty->ldisc.open)
                        (tty->ldisc.open)(tty);
        }
#endif
        if (info->blocked_open) {
                if (info->close_delay) {
                        current->state = TASK_INTERRUPTIBLE;
                        schedule_timeout(info->close_delay);
                }
                wake_up_interruptible(&info->open_wait);
        }
        info->flags &= ~(S_NORMAL_ACTIVE|S_CLOSING);
        wake_up_interruptible(&info->close_wait);
        local_irq_restore(flags);
}

/*
 * rs_hangup() --- called by tty_hangup() when a hangup is signaled.
 */
void rs_hangup(struct tty_struct *tty)
{
        struct NIOS_serial * info = (struct NIOS_serial *)tty->driver_data;

        if (serial_paranoia_check(info, tty->name, "rs_hangup"))
                return;

        rs_flush_buffer(tty);
        shutdown(info);
        info->event = 0;
        info->count = 0;
        info->flags &= ~S_NORMAL_ACTIVE;
        info->tty = 0;
        wake_up_interruptible(&info->open_wait);
}

/*
 * ------------------------------------------------------------
 * rs_open() and friends
 * ------------------------------------------------------------
 */
static int block_til_ready(struct tty_struct *tty, struct file * filp,
                           struct NIOS_serial *info)
{
        DECLARE_WAITQUEUE(wait, current);
        int             retval;
        int             do_clocal = 0;

        /*
         * If the device is in the middle of being closed, then block
         * until it's done, and then try again.
         */
        if (info->flags & S_CLOSING) {
                interruptible_sleep_on(&info->close_wait);
#ifdef SERIAL_DO_RESTART
                if (info->flags & S_HUP_NOTIFY)
                        return -EAGAIN;
                else
                        return -ERESTARTSYS;
#else
                return -EAGAIN;
#endif
        }

        /*
         * If non-blocking mode is set, or the port is not enabled,
         * then make the check up front and then exit.
         */
        if ((filp->f_flags & O_NONBLOCK) ||
            (tty->flags & (1 << TTY_IO_ERROR))) {
                info->flags |= S_NORMAL_ACTIVE;
                return 0;
        }

        if (tty->termios->c_cflag & CLOCAL)
                        do_clocal = 1;

        /*
         * Block waiting for the carrier detect and the line to become
         * free (i.e., not in use by the callout).  While we are in
         * this loop, info->count is dropped by one, so that
         * rs_close() knows when to free things.  We restore it upon
         * exit, either normal or abnormal.
         */
        retval = 0;
        add_wait_queue(&info->open_wait, &wait);

        info->count--;
        info->blocked_open++;
        while (1) {
                local_irq_disable();
                NIOS_rtsdtr(info, 1);
                local_irq_enable();
                current->state = TASK_INTERRUPTIBLE;
                if (tty_hung_up_p(filp) ||
                    !(info->flags & S_INITIALIZED)) {
#ifdef SERIAL_DO_RESTART
                        if (info->flags & S_HUP_NOTIFY)
                                retval = -EAGAIN;
                        else
                                retval = -ERESTARTSYS;
#else
                        retval = -EAGAIN;
#endif
                        break;
                }
                if (!(info->flags & S_CLOSING) && do_clocal)
                        break;
                if (signal_pending(current)) {
                        retval = -ERESTARTSYS;
                        break;
                }
                schedule();
        }
        current->state = TASK_RUNNING;
        remove_wait_queue(&info->open_wait, &wait);
        if (!tty_hung_up_p(filp))
                info->count++;
        info->blocked_open--;

        if (retval)
                return retval;
        info->flags |= S_NORMAL_ACTIVE;
        return 0;
}

/*
 * This routine is called whenever a serial port is opened.  It
 * enables interrupts for a serial port, linking in its S structure into
 * the IRQ chain.   It also performs the serial-specific
 * initialization for the tty structure.
 */
int rs_open(struct tty_struct *tty, struct file * filp)
{
        struct NIOS_serial      *info;
        int                     retval, line;

        line = tty->index;

        if (line >=serial_driver->num) /* too many */
                return -ENODEV;

        info = &nios_soft[line];

        if (serial_paranoia_check(info, tty->name, "rs_open"))
                return -ENODEV;

        info->count++;
        tty->driver_data = info;
        info->tty = tty;

        /*
         * Start up serial port
         */
        retval = startup(info);
        if (retval)
                return retval;

        return block_til_ready(tty, filp, info);
}

/* Finally, routines used to initialize the serial driver. */

static void show_serial_version(void)
{
        printk("NIOS serial driver version 0.0\n");
}



static struct tty_operations rs_ops = {
        .open = rs_open,
        .close = rs_close,
        .write = rs_write,
        .flush_chars = rs_flush_chars,
        .write_room = rs_write_room,
        .chars_in_buffer = rs_chars_in_buffer,
        .flush_buffer = rs_flush_buffer,
        .ioctl = rs_ioctl,
        .throttle = rs_throttle,
        .unthrottle = rs_unthrottle,
        .set_termios = rs_set_termios,
        .stop = rs_stop,
        .start = rs_start,
        .hangup = rs_hangup,
        .set_ldisc = rs_set_ldisc,
};

/* rs_init inits the driver */
static int __init rs_nios_init(void)
{
        int flags;
        struct NIOS_serial *info;
        int                     i;

        serial_driver = alloc_tty_driver(NR_PORTS);
        if (!serial_driver)
                return -ENOMEM;

        show_serial_version();

        /* Initialize the tty_driver structure */
        /* SPARC: Not all of this is exactly right for us. */

        serial_driver->name = "ttyS";
        serial_driver->major = TTY_MAJOR;
        serial_driver->minor_start = 64;
        serial_driver->type = TTY_DRIVER_TYPE_SERIAL;
        serial_driver->subtype = SERIAL_TYPE_NORMAL;
        serial_driver->init_termios = tty_std_termios;
        serial_driver->init_termios.c_cflag = 
                B115200 | CS8 | CREAD | HUPCL | CLOCAL;
        serial_driver->flags = TTY_DRIVER_REAL_RAW;
        tty_set_operations(serial_driver, &rs_ops);

        if (tty_register_driver(serial_driver)) {
                put_tty_driver(serial_driver);
                printk(KERN_ERR "Couldn't register serial driver\n");
                return -ENOMEM;
        }

        local_irq_save(flags);

        /*
         *      Configure all the attached serial ports.
         */
        for (i = 0, info = nios_soft; (i < NR_PORTS); i++, info++) {
                info->magic = SERIAL_MAGIC;
                info->tty = 0;
                info->custom_divisor = 16;
                info->close_delay = 50;
                info->closing_wait = 3000;
                info->x_char = 0;
                info->event = 0;
                info->count = 0;
                info->blocked_open = 0;
                INIT_WORK(&info->tqueue, do_softint, info);
                INIT_WORK(&info->tqueue_hangup, do_serial_hangup, info);
                init_waitqueue_head(&info->open_wait);
                init_waitqueue_head(&info->close_wait);
                info->line = i;

                printk("%s%d (irq = %d) is a builtin NIOS UART\n",
                        serial_driver->name, info->line, info->irq);

//              rs_setsignals(info, 0, 0);
                if (request_irq(info->irq, rs_interrupt, 0, "NIOS serial", info))
                        panic("Unable to attach NIOS serial interrupt\n");
        }

        local_irq_restore(flags);
        return 0;
}

/*
 * register_serial and unregister_serial allows for serial ports to be
 * configured at run-time, to support PCMCIA modems.
 */
/* NIOS: Unused at this time, just here to make things link. */
int register_serial(struct serial_struct *req)
{
        return -1;
}

void unregister_serial(int line)
{
        return;
}

module_init(rs_nios_init);

#ifdef CONFIG_NIOS_SERIAL_CONSOLE
int nios_console_setup(struct console *cp, char *arg)
{
        return 0;
}


static struct tty_driver *nios_console_device(struct console *c, int *index)
{
        *index = c->index;
        return serial_driver;
}


void nios_console_write (struct console *co, const char *str,
                           unsigned int count)
{
    while (count--) {
        if (*str == '\n')
           rs_put_char('\r', nios_soft);
        rs_put_char( *str++, nios_soft);
    }
}


static struct console nios_driver = {
        .name           = "ttyS",
        .write          = nios_console_write,
        .device         = nios_console_device,
        .setup          = nios_console_setup,
        .flags          = CON_PRINTBUFFER,
        .index          = -1,
};


static int __init nios_console_init(void)
{
        register_console(&nios_driver);
        return 0;
}

console_initcall(nios_console_init);
#endif /* CONFIG_NIOS_SERIAL_CONSOLE */