Import 2.3.16

[davej-history.git] / drivers / sgi / char / sgiserial.c

/* sgiserial.c: Serial port driver for SGI machines.
 *
 * Copyright (C) 1996 David S. Miller (dm@engr.sgi.com)
 *
 */

#include <linux/config.h> /* for CONFIG_REMOTE_DEBUG */
#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/delay.h>
#include <linux/console.h>
#include <linux/init.h>

#include <asm/io.h>
#include <asm/irq.h>
#include <asm/sgialib.h>
#include <asm/system.h>
#include <asm/bitops.h>
#include <asm/sgihpc.h>
#include <asm/sgint23.h>
#include <asm/uaccess.h>

#include "sgiserial.h"

#define NUM_SERIAL 1     /* One chip on board. */
#define NUM_CHANNELS (NUM_SERIAL * 2)

extern wait_queue_head_t keypress_wait;

struct sgi_zslayout *zs_chips[NUM_SERIAL] = { 0, };
struct sgi_zschannel *zs_channels[NUM_CHANNELS] = { 0, 0, };
struct sgi_zschannel *zs_conschan;
struct sgi_zschannel *zs_kgdbchan;

struct sgi_serial zs_soft[NUM_CHANNELS];
struct sgi_serial *zs_chain;  /* IRQ servicing chain */
static int zilog_irq = 21;

/* Console hooks... */
static int zs_cons_chanout = 0;
static int zs_cons_chanin = 0;
struct sgi_serial *zs_consinfo = 0;

static unsigned char kgdb_regs[16] = {
        0, 0, 0,                     /* write 0, 1, 2 */
        (Rx8 | RxENABLE),            /* write 3 */
        (X16CLK | SB1 | PAR_EVEN),   /* write 4 */
        (Tx8 | TxENAB),              /* write 5 */
        0, 0, 0,                     /* write 6, 7, 8 */
        (NV),                        /* write 9 */
        (NRZ),                       /* write 10 */
        (TCBR | RCBR),               /* write 11 */
        0, 0,                        /* BRG time constant, write 12 + 13 */
        (BRENABL),                   /* write 14 */
        (DCDIE)                      /* write 15 */
};

static unsigned char zscons_regs[16] = {
        0,                           /* write 0 */
        (EXT_INT_ENAB | INT_ALL_Rx), /* write 1 */
        0,                           /* write 2 */
        (Rx8 | RxENABLE),            /* write 3 */
        (X16CLK),                    /* write 4 */
        (DTR | Tx8 | TxENAB),        /* write 5 */
        0, 0, 0,                     /* write 6, 7, 8 */
        (NV | MIE),                  /* write 9 */
        (NRZ),                       /* write 10 */
        (TCBR | RCBR),               /* write 11 */
        0, 0,                        /* BRG time constant, write 12 + 13 */
        (BRENABL),                   /* write 14 */
        (DCDIE | CTSIE | TxUIE | BRKIE) /* write 15 */
};

#define ZS_CLOCK         3672000   /* Zilog input clock rate */

DECLARE_TASK_QUEUE(tq_serial);

struct tty_driver serial_driver, callout_driver;
static int serial_refcount;

/* serial subtype definitions */
#define SERIAL_TYPE_NORMAL      1
#define SERIAL_TYPE_CALLOUT     2
  
/* 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_STROBE_TIME 10
#define RS_ISR_PASS_LIMIT 256

#define _INLINE_ inline

static void change_speed(struct sgi_serial *info);

static struct tty_struct *serial_table[NUM_CHANNELS];
static struct termios *serial_termios[NUM_CHANNELS];
static struct termios *serial_termios_locked[NUM_CHANNELS];

#ifndef MIN
#define MIN(a,b)        ((a) < (b) ? (a) : (b))
#endif

/*
 * 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[4096]; /* This is cheating */
static DECLARE_MUTEX(tmp_buf_sem);

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

        if (!info) {
                printk(badinfo, MAJOR(device), MINOR(device), routine);
                return 1;
        }
        if (info->magic != SERIAL_MAGIC) {
                printk(badmagic, MAJOR(device), MINOR(device), 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 };

/* 
 * Reading and writing Zilog8530 registers.  The delays are to make this
 * driver work on the Sun4 which needs a settling delay after each chip
 * register access, other machines handle this in hardware via auxiliary
 * flip-flops which implement the settle time we do in software.
 *
 * read_zsreg() and write_zsreg() may get called from rs_kgdb_hook() before
 * interrupts are enabled. Therefore we have to check ioc_iocontrol before we
 * access it.
 */
static inline unsigned char read_zsreg(struct sgi_zschannel *channel, unsigned char reg)
{
        unsigned char retval;
        volatile unsigned char junk;

        udelay(2);
        channel->control = reg;
        if (ioc_icontrol)
                junk = ioc_icontrol->istat0;
        udelay(1);
        retval = channel->control;
        return retval;
}

static inline void write_zsreg(struct sgi_zschannel *channel, unsigned char reg, unsigned char value)
{
        volatile unsigned char junk;

        udelay(2);
        channel->control = reg;
        if (ioc_icontrol)
                junk = ioc_icontrol->istat0;
        udelay(1);
        channel->control = value;
        if (ioc_icontrol)
                junk = ioc_icontrol->istat0;
        return;
}

static inline void load_zsregs(struct sgi_zschannel *channel, unsigned char *regs)
{
        ZS_CLEARERR(channel);
        ZS_CLEARFIFO(channel);
        /* Load 'em up */
        write_zsreg(channel, R4, regs[R4]);
        write_zsreg(channel, R10, regs[R10]);
        write_zsreg(channel, R3, regs[R3] & ~RxENABLE);
        write_zsreg(channel, R5, regs[R5] & ~TxENAB);
        write_zsreg(channel, R1, regs[R1]);
        write_zsreg(channel, R9, regs[R9]);
        write_zsreg(channel, R11, regs[R11]);
        write_zsreg(channel, R12, regs[R12]);
        write_zsreg(channel, R13, regs[R13]);
        write_zsreg(channel, R14, regs[R14]);
        write_zsreg(channel, R15, regs[R15]);
        write_zsreg(channel, R3, regs[R3]);
        write_zsreg(channel, R5, regs[R5]);
        return;
}

/* Sets or clears DTR/RTS on the requested line */
static inline void zs_rtsdtr(struct sgi_serial *ss, int set)
{
        if(set) {
                ss->curregs[5] |= (RTS | DTR);
                ss->pendregs[5] = ss->curregs[5];
                write_zsreg(ss->zs_channel, 5, ss->curregs[5]);
        } else {
                ss->curregs[5] &= ~(RTS | DTR);
                ss->pendregs[5] = ss->curregs[5];
                write_zsreg(ss->zs_channel, 5, ss->curregs[5]);
        }
        return;
}

static inline void kgdb_chaninit(struct sgi_serial *ss, int intson, int bps)
{
        int brg;

        if(intson) {
                kgdb_regs[R1] = INT_ALL_Rx;
                kgdb_regs[R9] |= MIE;
        } else {
                kgdb_regs[R1] = 0;
                kgdb_regs[R9] &= ~MIE;
        }
        brg = BPS_TO_BRG(bps, ZS_CLOCK/ss->clk_divisor);
        kgdb_regs[R12] = (brg & 255);
        kgdb_regs[R13] = ((brg >> 8) & 255);
        load_zsregs(ss->zs_channel, kgdb_regs);
}

/* Utility routines for the Zilog */
static inline int get_zsbaud(struct sgi_serial *ss)
{
        struct sgi_zschannel *channel = ss->zs_channel;
        int brg;

        /* The baud rate is split up between two 8-bit registers in
         * what is termed 'BRG time constant' format in my docs for
         * the chip, it is a function of the clk rate the chip is
         * receiving which happens to be constant.
         */
        brg = ((read_zsreg(channel, 13)&0xff) << 8);
        brg |= (read_zsreg(channel, 12)&0xff);
        return BRG_TO_BPS(brg, (ZS_CLOCK/(ss->clk_divisor)));
}

/*
 * ------------------------------------------------------------
 * 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 sgi_serial *info = (struct sgi_serial *)tty->driver_data;
        unsigned long flags;

        if (serial_paranoia_check(info, tty->device, "rs_stop"))
                return;
        
        save_flags(flags); cli();
        if (info->curregs[5] & TxENAB) {
                info->curregs[5] &= ~TxENAB;
                info->pendregs[5] &= ~TxENAB;
                write_zsreg(info->zs_channel, 5, info->curregs[5]);
        }
        restore_flags(flags);
}

static void rs_start(struct tty_struct *tty)
{
        struct sgi_serial *info = (struct sgi_serial *)tty->driver_data;
        unsigned long flags;
        
        if (serial_paranoia_check(info, tty->device, "rs_start"))
                return;
        
        save_flags(flags); cli();
        if (info->xmit_cnt && info->xmit_buf && !(info->curregs[5] & TxENAB)) {
                info->curregs[5] |= TxENAB;
                info->pendregs[5] = info->curregs[5];
                write_zsreg(info->zs_channel, 5, info->curregs[5]);
        }
        restore_flags(flags);
}

/* Drop into either the boot monitor or kadb upon receiving a break
 * from keyboard/console input.
 */
static void batten_down_hatches(void)
{
        prom_imode();
#if 0
        /* If we are doing kadb, we call the debugger
         * else we just drop into the boot monitor.
         * Note that we must flush the user windows
         * first before giving up control.
         */
        printk("\n");
        if((((unsigned long)linux_dbvec)>=DEBUG_FIRSTVADDR) &&
           (((unsigned long)linux_dbvec)<=DEBUG_LASTVADDR))
                sp_enter_debugger();
        else
                prom_halt();

        /* XXX We want to notify the keyboard driver that all
         * XXX keys are in the up state or else weird things
         * XXX happen...
         */
#endif
        return;
}

/* On receive, this clears errors and the receiver interrupts */
static inline void rs_recv_clear(struct sgi_zschannel *zsc)
{
        volatile unsigned char junk;

        udelay(2);
        zsc->control = ERR_RES;
        junk = ioc_icontrol->istat0;
        udelay(2);
        zsc->control = RES_H_IUS;
        junk = ioc_icontrol->istat0;
}

/*
 * ----------------------------------------------------------------------
 *
 * Here starts the interrupt handling routines.  All of the following
 * subroutines are declared as inline and are folded into
 * rs_interrupt().  They were separated out for readability's sake.
 *
 * Note: rs_interrupt() is a "fast" interrupt, which means that it
 * runs with interrupts turned off.  People who may want to modify
 * rs_interrupt() should try to keep the interrupt handler as fast as
 * possible.  After you are done making modifications, it is not a bad
 * idea to do:
 * 
 * gcc -S -DKERNEL -Wall -Wstrict-prototypes -O6 -fomit-frame-pointer serial.c
 *
 * and look at the resulting assemble code in serial.s.
 *
 *                              - Ted Ts'o (tytso@mit.edu), 7-Mar-93
 * -----------------------------------------------------------------------
 */

/*
 * This routine is used by the interrupt handler to schedule
 * processing in the software interrupt portion of the driver.
 */
static _INLINE_ void rs_sched_event(struct sgi_serial *info,
                                    int event)
{
        info->event |= 1 << event;
        queue_task(&info->tqueue, &tq_serial);
        mark_bh(SERIAL_BH);
}

#ifdef CONFIG_REMOTE_DEBUG
extern void set_async_breakpoint(unsigned int epc);
#endif

static _INLINE_ void receive_chars(struct sgi_serial *info, struct pt_regs *regs)
{
        struct tty_struct *tty = info->tty;
        volatile unsigned char junk;
        unsigned char ch, stat;

        udelay(2);
        ch = info->zs_channel->data;
        junk = ioc_icontrol->istat0;
        udelay(2);
        stat = read_zsreg(info->zs_channel, R1);

        /* If this is the console keyboard, we need to handle
         * L1-A's here.
         */
        if(info->is_cons) {
                if(ch==0) { /* whee, break received */
                        batten_down_hatches();
                        rs_recv_clear(info->zs_channel);
                        return;
                } else if (ch == 1) {
                        show_state();
                        return;
                } else if (ch == 2) {
                        return;
                }
                /* It is a 'keyboard interrupt' ;-) */
                wake_up(&keypress_wait);
        }
        /* Look for kgdb 'stop' character, consult the gdb documentation
         * for remote target debugging and arch/sparc/kernel/sparc-stub.c
         * to see how all this works.
         */
#ifdef CONFIG_REMOTE_DEBUG
        if((info->kgdb_channel) && (ch =='\003')) {
                set_async_breakpoint(read_32bit_cp0_register(CP0_EPC));
                goto clear_and_exit;
        }
#endif
        if(!tty)
                goto clear_and_exit;

        if (tty->flip.count >= TTY_FLIPBUF_SIZE)
                queue_task(&tty->flip.tqueue, &tq_timer);
        tty->flip.count++;
        if(stat & PAR_ERR)
                *tty->flip.flag_buf_ptr++ = TTY_PARITY;
        else if(stat & Rx_OVR)
                *tty->flip.flag_buf_ptr++ = TTY_OVERRUN;
        else if(stat & CRC_ERR)
                *tty->flip.flag_buf_ptr++ = TTY_FRAME;
        else
                *tty->flip.flag_buf_ptr++ = 0; /* XXX */
        *tty->flip.char_buf_ptr++ = ch;

        queue_task(&tty->flip.tqueue, &tq_timer);

clear_and_exit:
        rs_recv_clear(info->zs_channel);
        return;
}

static _INLINE_ void transmit_chars(struct sgi_serial *info)
{
        volatile unsigned char junk;

        /* P3: In theory we have to test readiness here because a
         * serial console can clog the chip through rs_put_char().
         * David did not do this. I think he relies on 3-chars FIFO in 8530.
         * Let's watch for lost _output_ characters. XXX
         */

        /* SGI ADDENDUM: On most SGI machines, the Zilog does possess
         *               a 16 or 17 byte fifo, so no worries. -dm
         */

        if (info->x_char) {
                /* Send next char */
                udelay(2);
                info->zs_channel->data = info->x_char;
                junk = ioc_icontrol->istat0;

                info->x_char = 0;
                goto clear_and_return;
        }

        if((info->xmit_cnt <= 0) || info->tty->stopped) {
                /* That's peculiar... */
                udelay(2);
                info->zs_channel->control = RES_Tx_P;
                junk = ioc_icontrol->istat0;
                goto clear_and_return;
        }

        /* Send char */
        udelay(2);
        info->zs_channel->data = info->xmit_buf[info->xmit_tail++];
        junk = ioc_icontrol->istat0;

        info->xmit_tail = info->xmit_tail & (SERIAL_XMIT_SIZE-1);
        info->xmit_cnt--;

        if (info->xmit_cnt < WAKEUP_CHARS)
                rs_sched_event(info, RS_EVENT_WRITE_WAKEUP);

        if(info->xmit_cnt <= 0) {
                udelay(2);
                info->zs_channel->control = RES_Tx_P;
                junk = ioc_icontrol->istat0;
                goto clear_and_return;
        }

clear_and_return:
        /* Clear interrupt */
        udelay(2);
        info->zs_channel->control = RES_H_IUS;
        junk = ioc_icontrol->istat0;
        return;
}

static _INLINE_ void status_handle(struct sgi_serial *info)
{
        volatile unsigned char junk;
        unsigned char status;

        /* Get status from Read Register 0 */
        udelay(2);
        status = info->zs_channel->control;
        junk = ioc_icontrol->istat0;
        /* Clear status condition... */
        udelay(2);
        info->zs_channel->control = RES_EXT_INT;
        junk = ioc_icontrol->istat0;
        /* Clear the interrupt */
        udelay(2);
        info->zs_channel->control = RES_H_IUS;
        junk = ioc_icontrol->istat0;

#if 0
        if(status & DCD) {
                if((info->tty->termios->c_cflag & CRTSCTS) &&
                   ((info->curregs[3] & AUTO_ENAB)==0)) {
                        info->curregs[3] |= AUTO_ENAB;
                        info->pendregs[3] |= AUTO_ENAB;
                        write_zsreg(info->zs_channel, 3, info->curregs[3]);
                }
        } else {
                if((info->curregs[3] & AUTO_ENAB)) {
                        info->curregs[3] &= ~AUTO_ENAB;
                        info->pendregs[3] &= ~AUTO_ENAB;
                        write_zsreg(info->zs_channel, 3, info->curregs[3]);
                }
        }
#endif
        /* Whee, if this is console input and this is a
         * 'break asserted' status change interrupt, call
         * the boot prom.
         */
        if((status & BRK_ABRT) && info->break_abort)
                batten_down_hatches();

        /* XXX Whee, put in a buffer somewhere, the status information
         * XXX whee whee whee... Where does the information go...
         */
        return;
}

/*
 * This is the serial driver's generic interrupt routine
 */
void rs_interrupt(int irq, void *dev_id, struct pt_regs * regs)
{
        struct sgi_serial * info = (struct sgi_serial *) dev_id;
        unsigned char zs_intreg;

        zs_intreg = read_zsreg(info->zs_next->zs_channel, 3);

        /* NOTE: The read register 3, which holds the irq status,
         *       does so for both channels on each chip.  Although
         *       the status value itself must be read from the A
         *       channel and is only valid when read from channel A.
         *       Yes... broken hardware...
         */
#define CHAN_A_IRQMASK (CHARxIP | CHATxIP | CHAEXT)
#define CHAN_B_IRQMASK (CHBRxIP | CHBTxIP | CHBEXT)

        /* *** Chip 1 *** */
        /* Channel B -- /dev/ttyb, could be the console */
        if(zs_intreg & CHAN_B_IRQMASK) {
                if (zs_intreg & CHBRxIP)
                        receive_chars(info, regs);
                if (zs_intreg & CHBTxIP)
                        transmit_chars(info);
                if (zs_intreg & CHBEXT)
                        status_handle(info);
        }

        info=info->zs_next;

        /* Channel A -- /dev/ttya, could be the console */
        if(zs_intreg & CHAN_A_IRQMASK) {
                if (zs_intreg & CHARxIP)
                        receive_chars(info, regs);
                if (zs_intreg & CHATxIP)
                        transmit_chars(info);
                if (zs_intreg & CHAEXT)
                        status_handle(info);
        }
}

/*
 * -------------------------------------------------------------------
 * Here ends the serial interrupt routines.
 * -------------------------------------------------------------------
 */

/*
 * This routine is used to handle the "bottom half" processing for the
 * serial driver, known also the "software interrupt" processing.
 * This processing is done at the kernel interrupt level, after the
 * rs_interrupt() has returned, BUT WITH INTERRUPTS TURNED ON.  This
 * is where time-consuming activities which can not be done in the
 * interrupt driver proper are done; the interrupt driver schedules
 * them using rs_sched_event(), and they get done here.
 */
static void do_serial_bh(void)
{
        run_task_queue(&tq_serial);
}

static void do_softint(void *private_)
{
        struct sgi_serial       *info = (struct sgi_serial *) private_;
        struct tty_struct       *tty;
        
        tty = info->tty;
        if (!tty)
                return;

        if (test_and_clear_bit(RS_EVENT_WRITE_WAKEUP, &info->event)) {
                if ((tty->flags & (1 << TTY_DO_WRITE_WAKEUP)) &&
                    tty->ldisc.write_wakeup)
                        (tty->ldisc.write_wakeup)(tty);
                wake_up_interruptible(&tty->write_wait);
        }
}

/*
 * 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 sgi_serial       *info = (struct sgi_serial *) private_;
        struct tty_struct       *tty;
        
        tty = info->tty;
        if (!tty)
                return;

        tty_hangup(tty);
}


/*
 * This subroutine is called when the RS_TIMER goes off.  It is used
 * by the serial driver to handle ports that do not have an interrupt
 * (irq=0).  This doesn't work at all for 16450's, as a sun has a Z8530.
 */
 
static void rs_timer(void)
{
        printk("rs_timer called\n");
        prom_halt();
        return;
}

static int startup(struct sgi_serial * info)
{
        volatile unsigned char junk;
        unsigned long flags;

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

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

        save_flags(flags); cli();

#ifdef SERIAL_DEBUG_OPEN
        printk("starting up ttys%d (irq %d)...", info->line, info->irq);
#endif

        /*
         * Clear the FIFO buffers and disable them
         * (they will be reenabled in change_speed())
         */
        ZS_CLEARFIFO(info->zs_channel);
        info->xmit_fifo_size = 1;

        /*
         * Clear the interrupt registers.
         */
        udelay(2);
        info->zs_channel->control = ERR_RES;
        junk = ioc_icontrol->istat0;
        udelay(2);
        info->zs_channel->control = RES_H_IUS;
        junk = ioc_icontrol->istat0;

        /*
         * Now, initialize the Zilog
         */
        zs_rtsdtr(info, 1);

        /*
         * Finally, enable sequencing and interrupts
         */
        info->curregs[1] |= (info->curregs[1] & ~0x18) | (EXT_INT_ENAB|INT_ALL_Rx);
        info->pendregs[1] = info->curregs[1];
        info->curregs[3] |= (RxENABLE | Rx8);
        info->pendregs[3] = info->curregs[3];
        /* We enable Tx interrupts as needed. */
        info->curregs[5] |= (TxENAB | Tx8);
        info->pendregs[5] = info->curregs[5];
        info->curregs[9] |= (NV | MIE);
        info->pendregs[9] = info->curregs[9];
        write_zsreg(info->zs_channel, 3, info->curregs[3]);
        write_zsreg(info->zs_channel, 5, info->curregs[5]);
        write_zsreg(info->zs_channel, 9, info->curregs[9]);
        
        /*
         * And clear the interrupt registers again for luck.
         */
        udelay(2);
        info->zs_channel->control = ERR_RES;
        junk = ioc_icontrol->istat0;
        udelay(2);
        info->zs_channel->control = RES_H_IUS;
        junk = ioc_icontrol->istat0;

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

        /*
         * Set up serial timers...
         */
#if 0  /* Works well and stops the machine. */
        timer_table[RS_TIMER].expires = jiffies + 2;
        timer_active |= 1 << RS_TIMER;
#endif

        /*
         * and set the speed of the serial port
         */
        change_speed(info);

        info->flags |= ZILOG_INITIALIZED;
        restore_flags(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 sgi_serial * info)
{
        unsigned long   flags;

        if (!(info->flags & ZILOG_INITIALIZED))
                return;

#ifdef SERIAL_DEBUG_OPEN
        printk("Shutting down serial port %d (irq %d)....", info->line,
               info->irq);
#endif
        
        save_flags(flags); cli(); /* 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 &= ~ZILOG_INITIALIZED;
        restore_flags(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 sgi_serial *info)
{
        unsigned short port;
        unsigned cflag;
        int     i;
        int     brg;

        if (!info->tty || !info->tty->termios)
                return;
        cflag = info->tty->termios->c_cflag;
        if (!(port = info->port))
                return;
        i = cflag & CBAUD;
        if (i & CBAUDEX) {
                /* XXX CBAUDEX is not obeyed.
                 * It is impossible at a 32bits SPARC.
                 * But we have to report this to user ... someday.
                 */
                i = B9600;
        }
        if (i == 0) {
                /* XXX B0, hangup the line. */
                do_serial_hangup(info);
        } else if (baud_table[i]) {
                info->zs_baud = baud_table[i];
                info->clk_divisor = 16;

                info->curregs[4] = X16CLK;
                info->curregs[11] = TCBR | RCBR;
                brg = BPS_TO_BRG(info->zs_baud, ZS_CLOCK/info->clk_divisor);
                info->curregs[12] = (brg & 255);
                info->curregs[13] = ((brg >> 8) & 255);
                info->curregs[14] = BRENABL;
        }

        /* byte size and parity */
        switch (cflag & CSIZE) {
        case CS5:
                info->curregs[3] &= ~(0xc0);
                info->curregs[3] |= Rx5;
                info->pendregs[3] = info->curregs[3];
                info->curregs[5] &= ~(0xe0);
                info->curregs[5] |= Tx5;
                info->pendregs[5] = info->curregs[5];
                break;
        case CS6:
                info->curregs[3] &= ~(0xc0);
                info->curregs[3] |= Rx6;
                info->pendregs[3] = info->curregs[3];
                info->curregs[5] &= ~(0xe0);
                info->curregs[5] |= Tx6;
                info->pendregs[5] = info->curregs[5];
                break;
        case CS7:
                info->curregs[3] &= ~(0xc0);
                info->curregs[3] |= Rx7;
                info->pendregs[3] = info->curregs[3];
                info->curregs[5] &= ~(0xe0);
                info->curregs[5] |= Tx7;
                info->pendregs[5] = info->curregs[5];
                break;
        case CS8:
        default: /* defaults to 8 bits */
                info->curregs[3] &= ~(0xc0);
                info->curregs[3] |= Rx8;
                info->pendregs[3] = info->curregs[3];
                info->curregs[5] &= ~(0xe0);
                info->curregs[5] |= Tx8;
                info->pendregs[5] = info->curregs[5];
                break;
        }
        info->curregs[4] &= ~(0x0c);
        if (cflag & CSTOPB) {
                info->curregs[4] |= SB2;
        } else {
                info->curregs[4] |= SB1;
        }
        info->pendregs[4] = info->curregs[4];
        if (cflag & PARENB) {
                info->curregs[4] |= PAR_ENA;
                info->pendregs[4] |= PAR_ENA;
        } else {
                info->curregs[4] &= ~PAR_ENA;
                info->pendregs[4] &= ~PAR_ENA;
        }
        if (!(cflag & PARODD)) {
                info->curregs[4] |= PAR_EVEN;
                info->pendregs[4] |= PAR_EVEN;
        } else {
                info->curregs[4] &= ~PAR_EVEN;
                info->pendregs[4] &= ~PAR_EVEN;
        }

        /* Load up the new values */
        load_zsregs(info->zs_channel, info->curregs);

        return;
}

/* This is for console output over ttya/ttyb */
static void rs_put_char(char ch)
{
        struct sgi_zschannel *chan = zs_conschan;
        volatile unsigned char junk;
        int flags, loops = 0;

        save_flags(flags); cli();
        while(((junk = chan->control) & Tx_BUF_EMP)==0 && loops < 10000) {
                loops++;
                udelay(2);
        }

        udelay(2);
        chan->data = ch;
        junk = ioc_icontrol->istat0;
        restore_flags(flags);
}

/* These are for receiving and sending characters under the kgdb
 * source level kernel debugger.
 */
int putDebugChar(char kgdb_char)
{
        struct sgi_zschannel *chan = zs_kgdbchan;
        volatile unsigned char junk;
        unsigned long flags;

        save_flags(flags); cli();
        udelay(2);
        while((chan->control & Tx_BUF_EMP)==0)
                udelay(2);

        udelay(2);
        chan->data = kgdb_char;
        junk = ioc_icontrol->istat0;
        restore_flags(flags);

        return 1;
}

char getDebugChar(void)
{
        struct sgi_zschannel *chan = zs_kgdbchan;
        unsigned char junk;

        while((chan->control & Rx_CH_AV)==0)
                udelay(2);

        junk = ioc_icontrol->istat0;
        udelay(2);
        return chan->data;
}

/*
 * Fair output driver allows a process to speak.
 */
static void rs_fair_output(void)
{
        int left;               /* Output no more than that */
        unsigned long flags;
        struct sgi_serial *info = zs_consinfo;
        volatile unsigned char junk;
        char c;

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

        save_flags(flags);  cli();
        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--;
                restore_flags(flags);

                rs_put_char(c);

                save_flags(flags);  cli();
                left = MIN(info->xmit_cnt, left-1);
        }

        /* Last character is being transmitted now (hopefully). */
        udelay(2);
        zs_conschan->control = RES_Tx_P;
        junk = ioc_icontrol->istat0;

        restore_flags(flags);
        return;
}


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

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

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

        save_flags(flags);
        while (1) {
                cli();          
                c = MIN(count, MIN(SERIAL_XMIT_SIZE - info->xmit_cnt - 1,
                                   SERIAL_XMIT_SIZE - info->xmit_head));
                if (c <= 0)
                        break;

                if (from_user) {
                        down(&tmp_buf_sem);
                        copy_from_user(tmp_buf, buf, c);
                        c = MIN(c, MIN(SERIAL_XMIT_SIZE - info->xmit_cnt - 1,
                                       SERIAL_XMIT_SIZE - info->xmit_head));
                        memcpy(info->xmit_buf + info->xmit_head, tmp_buf, c);
                        up(&tmp_buf_sem);
                } else
                        memcpy(info->xmit_buf + info->xmit_head, buf, c);
                info->xmit_head = (info->xmit_head + c) & (SERIAL_XMIT_SIZE-1);
                info->xmit_cnt += c;
                restore_flags(flags);
                buf += c;
                count -= c;
                total += c;
        }
        if (info->xmit_cnt && !tty->stopped && !tty->hw_stopped &&
            !(info->curregs[5] & TxENAB)) {
                /* Enable transmitter */
                info->curregs[1] |= TxINT_ENAB|EXT_INT_ENAB;
                info->pendregs[1] |= TxINT_ENAB|EXT_INT_ENAB;
                write_zsreg(info->zs_channel, 1, info->curregs[1]);
                info->curregs[5] |= TxENAB;
                info->pendregs[5] |= TxENAB;
                write_zsreg(info->zs_channel, 5, info->curregs[5]);
        }
        restore_flags(flags);
        return total;
}

static int rs_write_room(struct tty_struct *tty)
{
        struct sgi_serial *info = (struct sgi_serial *)tty->driver_data;
        int     ret;
                                
        if (serial_paranoia_check(info, tty->device, "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 sgi_serial *info = (struct sgi_serial *)tty->driver_data;
                                
        if (serial_paranoia_check(info, tty->device, "rs_chars_in_buffer"))
                return 0;
        return info->xmit_cnt;
}

static void rs_flush_buffer(struct tty_struct *tty)
{
        struct sgi_serial *info = (struct sgi_serial *)tty->driver_data;
                                
        if (serial_paranoia_check(info, tty->device, "rs_flush_buffer"))
                return;
        cli();
        info->xmit_cnt = info->xmit_head = info->xmit_tail = 0;
        sti();
        wake_up_interruptible(&tty->write_wait);
        if ((tty->flags & (1 << TTY_DO_WRITE_WAKEUP)) &&
            tty->ldisc.write_wakeup)
                (tty->ldisc.write_wakeup)(tty);
}

static void rs_flush_chars(struct tty_struct *tty)
{
        struct sgi_serial *info = (struct sgi_serial *)tty->driver_data;
        unsigned long flags;

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

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

        /* Enable transmitter */
        save_flags(flags); cli();
        info->curregs[1] |= TxINT_ENAB|EXT_INT_ENAB;
        info->pendregs[1] |= TxINT_ENAB|EXT_INT_ENAB;
        write_zsreg(info->zs_channel, 1, info->curregs[1]);
        info->curregs[5] |= TxENAB;
        info->pendregs[5] |= TxENAB;
        write_zsreg(info->zs_channel, 5, info->curregs[5]);

        /*
         * Send a first (bootstrapping) character. A best solution is
         * to call transmit_chars() here which handles output in a
         * generic way. Current transmit_chars() not only transmits,
         * but resets interrupts also what we do not desire here.
         * XXX Discuss with David.
         */
        if (info->zs_channel->control & Tx_BUF_EMP) {
                volatile unsigned char junk;

                /* Send char */
                udelay(2);
                info->zs_channel->data = info->xmit_buf[info->xmit_tail++];
                junk = ioc_icontrol->istat0;
                info->xmit_tail = info->xmit_tail & (SERIAL_XMIT_SIZE-1);
                info->xmit_cnt--;
        }
        restore_flags(flags);
}

/*
 * ------------------------------------------------------------
 * 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 sgi_serial *info = (struct sgi_serial *)tty->driver_data;
#ifdef SERIAL_DEBUG_THROTTLE
        char    buf[64];
        
        printk("throttle %s: %d....\n", _tty_name(tty, buf),
               tty->ldisc.chars_in_buffer(tty));
#endif

        if (serial_paranoia_check(info, tty->device, "rs_throttle"))
                return;
        
        if (I_IXOFF(tty))
                info->x_char = STOP_CHAR(tty);

        /* Turn off RTS line */
        cli();
        info->curregs[5] &= ~RTS;
        info->pendregs[5] &= ~RTS;
        write_zsreg(info->zs_channel, 5, info->curregs[5]);
        sti();
}

static void rs_unthrottle(struct tty_struct * tty)
{
        struct sgi_serial *info = (struct sgi_serial *)tty->driver_data;
#ifdef SERIAL_DEBUG_THROTTLE
        char    buf[64];
        
        printk("unthrottle %s: %d....\n", _tty_name(tty, buf),
               tty->ldisc.chars_in_buffer(tty));
#endif

        if (serial_paranoia_check(info, tty->device, "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 */
        cli();
        info->curregs[5] |= RTS;
        info->pendregs[5] |= RTS;
        write_zsreg(info->zs_channel, 5, info->curregs[5]);
        sti();
}

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

static int get_serial_info(struct sgi_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;
        return copy_to_user(retinfo,&tmp,sizeof(*retinfo));
}

static int set_serial_info(struct sgi_serial * info,
                           struct serial_struct * new_info)
{
        struct serial_struct new_serial;
        struct sgi_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 & ~ZILOG_USR_MASK) !=
                     (info->flags & ~ZILOG_USR_MASK)))
                        return -EPERM;
                info->flags = ((info->flags & ~ZILOG_USR_MASK) |
                               (new_serial.flags & ZILOG_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 & ~ZILOG_FLAGS) |
                        (new_serial.flags & ZILOG_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 sgi_serial * info, unsigned int *value)
{
        volatile unsigned char junk;
        unsigned char status;

        cli();
        udelay(2);
        status = info->zs_channel->control;
        junk = ioc_icontrol->istat0;
        sti();
        return put_user(status,value);
}

/*
 * This routine sends a break character out the serial port.
 */
static void send_break( struct sgi_serial * info, int duration)
{
        if (!info->port)
                return;
        current->state = TASK_INTERRUPTIBLE;
        cli();
        write_zsreg(info->zs_channel, 5, (info->curregs[5] | SND_BRK));
        schedule_timeout(duration);
        write_zsreg(info->zs_channel, 5, info->curregs[5]);
        sti();
}

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

        if (serial_paranoia_check(info, tty->device, "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 = verify_area(VERIFY_WRITE, (void *) arg,sizeof(long));
                        if (error)
                                return error;
                        put_user(C_CLOCAL(tty) ? 1 : 0,
                                 (unsigned long *) arg);
                        return 0;
                case TIOCSSOFTCAR:
                        error = get_user(arg, (unsigned long *)arg);
                        if (error)
                                return error;
                        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 sgi_serial));
                        if (error)
                                return error;
                        copy_to_user((struct sun_serial *) arg,
                                    info, sizeof(struct sgi_serial));
                        return 0;
                        
                default:
                        return -ENOIOCTLCMD;
                }
        return 0;
}

static void rs_set_termios(struct tty_struct *tty, struct termios *old_termios)
{
        struct sgi_serial *info = (struct sgi_serial *)tty->driver_data;

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

        change_speed(info);

        if ((old_termios->c_cflag & CRTSCTS) &&
            !(tty->termios->c_cflag & CRTSCTS)) {
                tty->hw_stopped = 0;
                rs_start(tty);
        }
}

/*
 * ------------------------------------------------------------
 * 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
 * ZILOG 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 sgi_serial * info = (struct sgi_serial *)tty->driver_data;
        unsigned long flags;

        if (!info || serial_paranoia_check(info, tty->device, "rs_close"))
                return;
        
        save_flags(flags); cli();
        
        if (tty_hung_up_p(filp)) {
                restore_flags(flags);
                return;
        }
        
#ifdef SERIAL_DEBUG_OPEN
        printk("rs_close ttys%d, count = %d\n", info->line, info->count);
#endif
        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) {
                restore_flags(flags);
                return;
        }
        info->flags |= ZILOG_CLOSING;
        /*
         * Save the termios structure, since this port may have
         * separate termios for callout and dialin.
         */
        if (info->flags & ZILOG_NORMAL_ACTIVE)
                info->normal_termios = *tty->termios;
        if (info->flags & ZILOG_CALLOUT_ACTIVE)
                info->callout_termios = *tty->termios;
        /*
         * 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 != ZILOG_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.
         */
        /** if (!info->iscons) ... **/
        info->curregs[3] &= ~RxENABLE;
        info->pendregs[3] = info->curregs[3];
        write_zsreg(info->zs_channel, 3, info->curregs[3]);
        info->curregs[1] &= ~(0x18);
        info->pendregs[1] = info->curregs[1];
        write_zsreg(info->zs_channel, 1, info->curregs[1]);
        ZS_CLEARFIFO(info->zs_channel);

        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 (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);
        }
        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 &= ~(ZILOG_NORMAL_ACTIVE|ZILOG_CALLOUT_ACTIVE|
                         ZILOG_CLOSING);
        wake_up_interruptible(&info->close_wait);
        restore_flags(flags);
}

/*
 * rs_hangup() --- called by tty_hangup() when a hangup is signaled.
 */
void rs_hangup(struct tty_struct *tty)
{
        struct sgi_serial * info = (struct sgi_serial *)tty->driver_data;
        
        if (serial_paranoia_check(info, tty->device, "rs_hangup"))
                return;
        
        rs_flush_buffer(tty);
        shutdown(info);
        info->event = 0;
        info->count = 0;
        info->flags &= ~(ZILOG_NORMAL_ACTIVE|ZILOG_CALLOUT_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 sgi_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 & ZILOG_CLOSING) {
                interruptible_sleep_on(&info->close_wait);
#ifdef SERIAL_DO_RESTART
                if (info->flags & ZILOG_HUP_NOTIFY)
                        return -EAGAIN;
                else
                        return -ERESTARTSYS;
#else
                return -EAGAIN;
#endif
        }

        /*
         * If this is a callout device, then just make sure the normal
         * device isn't being used.
         */
        if (tty->driver.subtype == SERIAL_TYPE_CALLOUT) {
                if (info->flags & ZILOG_NORMAL_ACTIVE)
                        return -EBUSY;
                if ((info->flags & ZILOG_CALLOUT_ACTIVE) &&
                    (info->flags & ZILOG_SESSION_LOCKOUT) &&
                    (info->session != current->session))
                    return -EBUSY;
                if ((info->flags & ZILOG_CALLOUT_ACTIVE) &&
                    (info->flags & ZILOG_PGRP_LOCKOUT) &&
                    (info->pgrp != current->pgrp))
                    return -EBUSY;
                info->flags |= ZILOG_CALLOUT_ACTIVE;
                return 0;
        }
        
        /*
         * 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))) {
                if (info->flags & ZILOG_CALLOUT_ACTIVE)
                        return -EBUSY;
                info->flags |= ZILOG_NORMAL_ACTIVE;
                return 0;
        }

        if (info->flags & ZILOG_CALLOUT_ACTIVE) {
                if (info->normal_termios.c_cflag & CLOCAL)
                        do_clocal = 1;
        } else {
                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);
#ifdef SERIAL_DEBUG_OPEN
        printk("block_til_ready before block: ttys%d, count = %d\n",
               info->line, info->count);
#endif
        info->count--;
        info->blocked_open++;
        while (1) {
                cli();
                if (!(info->flags & ZILOG_CALLOUT_ACTIVE))
                        zs_rtsdtr(info, 1);
                sti();
                set_current_state(TASK_INTERRUPTIBLE);
                if (tty_hung_up_p(filp) ||
                    !(info->flags & ZILOG_INITIALIZED)) {
#ifdef SERIAL_DO_RESTART
                        if (info->flags & ZILOG_HUP_NOTIFY)
                                retval = -EAGAIN;
                        else
                                retval = -ERESTARTSYS;  
#else
                        retval = -EAGAIN;
#endif
                        break;
                }
                if (!(info->flags & ZILOG_CALLOUT_ACTIVE) &&
                    !(info->flags & ZILOG_CLOSING) && do_clocal)
                        break;
                if (signal_pending(current)) {
                        retval = -ERESTARTSYS;
                        break;
                }
#ifdef SERIAL_DEBUG_OPEN
                printk("block_til_ready blocking: ttys%d, count = %d\n",
                       info->line, info->count);
#endif
                schedule();
        }
        current->state = TASK_RUNNING;
        remove_wait_queue(&info->open_wait, &wait);
        if (!tty_hung_up_p(filp))
                info->count++;
        info->blocked_open--;
#ifdef SERIAL_DEBUG_OPEN
        printk("block_til_ready after blocking: ttys%d, count = %d\n",
               info->line, info->count);
#endif
        if (retval)
                return retval;
        info->flags |= ZILOG_NORMAL_ACTIVE;
        return 0;
}       

/*
 * This routine is called whenever a serial port is opened.  It
 * enables interrupts for a serial port, linking in its ZILOG 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 sgi_serial       *info;
        int                     retval, line;

        line = MINOR(tty->device) - tty->driver.minor_start;
        /* The zilog lines for the mouse/keyboard must be
         * opened using their respective drivers.
         */
        if ((line < 0) || (line >= NUM_CHANNELS))
                return -ENODEV;
        info = zs_soft + line;
        /* Is the kgdb running over this line? */
        if (info->kgdb_channel)
                return -ENODEV;
        if (serial_paranoia_check(info, tty->device, "rs_open"))
                return -ENODEV;
#ifdef SERIAL_DEBUG_OPEN
        printk("rs_open %s%d, count = %d\n", tty->driver.name, info->line,
               info->count);
#endif
        info->count++;
        tty->driver_data = info;
        info->tty = tty;

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

        retval = block_til_ready(tty, filp, info);
        if (retval) {
#ifdef SERIAL_DEBUG_OPEN
                printk("rs_open returning after block_til_ready with %d\n",
                       retval);
#endif
                return retval;
        }

        if ((info->count == 1) && (info->flags & ZILOG_SPLIT_TERMIOS)) {
                if (tty->driver.subtype == SERIAL_TYPE_NORMAL)
                        *tty->termios = info->normal_termios;
                else 
                        *tty->termios = info->callout_termios;
                change_speed(info);
        }

        info->session = current->session;
        info->pgrp = current->pgrp;

#ifdef SERIAL_DEBUG_OPEN
        printk("rs_open ttys%d successful...", info->line);
#endif
        return 0;
}

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

static void show_serial_version(void)
{
        printk("SGI Zilog8530 serial driver version 1.00\n");
}

/* Return layout for the requested zs chip number. */
static inline struct sgi_zslayout *get_zs(int chip)
{
        extern struct hpc3_miscregs *hpc3mregs;

        if(chip > 0) {
                prom_printf("Wheee, bogus zs chip number requested.\n");
                prom_getchar();
                romvec->imode();
        }
        return (struct sgi_zslayout *) (&hpc3mregs->ser1cmd);

}


static inline void
rs_cons_check(struct sgi_serial *ss, int channel)
{
        int i, o, io;
        static int msg_printed = 0;

        i = o = io = 0;

        /* Is this one of the serial console lines? */
        if((zs_cons_chanout != channel) &&
           (zs_cons_chanin != channel))
                return;
        zs_conschan = ss->zs_channel;
        zs_consinfo = ss;



        /* If this is console input, we handle the break received
         * status interrupt on this line to mean prom_halt().
         */
        if(zs_cons_chanin == channel) {
                ss->break_abort = 1;
                i = 1;
        }
        if(o && i)
                io = 1;
        if(ss->zs_baud != 9562) { /* Don't ask... */
                prom_printf("BAD console baud rate %d\n", ss->zs_baud);
                prom_getchar();
                prom_imode();
                panic("Console baud rate weirdness");
        }


        /* Set flag variable for this port so that it cannot be
         * opened for other uses by accident.
         */
        ss->is_cons = 1;

        if(io) {
                if(!msg_printed) {
                        printk("zs%d: console I/O\n", ((channel>>1)&1));
                        msg_printed = 1;
                }

        } else {
                printk("zs%d: console %s\n", ((channel>>1)&1),
                       (i==1 ? "input" : (o==1 ? "output" : "WEIRD")));

        }
}

volatile int test_done;

/* rs_init inits the driver */
int rs_init(void)
{
        int chip, channel, i, flags;
        struct sgi_serial *info;


        /* Setup base handler, and timer table. */
        init_bh(SERIAL_BH, do_serial_bh);
        timer_table[RS_TIMER].fn = rs_timer;
        timer_table[RS_TIMER].expires = 0;

        show_serial_version();

        /* Initialize the tty_driver structure */
        /* SGI: Not all of this is exactly right for us. */
        
        memset(&serial_driver, 0, sizeof(struct tty_driver));
        serial_driver.magic = TTY_DRIVER_MAGIC;
        serial_driver.name = "ttyS";
        serial_driver.major = TTY_MAJOR;
        serial_driver.minor_start = 64;
        serial_driver.num = NUM_CHANNELS;
        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 =
                B9600 | CS8 | CREAD | HUPCL | CLOCAL;
        serial_driver.flags = TTY_DRIVER_REAL_RAW;
        serial_driver.refcount = &serial_refcount;
        serial_driver.table = serial_table;
        serial_driver.termios = serial_termios;
        serial_driver.termios_locked = serial_termios_locked;

        serial_driver.open = rs_open;
        serial_driver.close = rs_close;
        serial_driver.write = rs_write;
        serial_driver.flush_chars = rs_flush_chars;
        serial_driver.write_room = rs_write_room;
        serial_driver.chars_in_buffer = rs_chars_in_buffer;
        serial_driver.flush_buffer = rs_flush_buffer;
        serial_driver.ioctl = rs_ioctl;
        serial_driver.throttle = rs_throttle;
        serial_driver.unthrottle = rs_unthrottle;
        serial_driver.set_termios = rs_set_termios;
        serial_driver.stop = rs_stop;
        serial_driver.start = rs_start;
        serial_driver.hangup = rs_hangup;

        /*
         * The callout device is just like normal device except for
         * major number and the subtype code.
         */
        callout_driver = serial_driver;
        callout_driver.name = "cua";
        callout_driver.major = TTYAUX_MAJOR;
        callout_driver.subtype = SERIAL_TYPE_CALLOUT;

        if (tty_register_driver(&serial_driver))
                panic("Couldn't register serial driver\n");
        if (tty_register_driver(&callout_driver))
                panic("Couldn't register callout driver\n");
        
        save_flags(flags); cli();

        /* Set up our interrupt linked list */
        zs_chain = &zs_soft[0];
        zs_soft[0].zs_next = &zs_soft[1];
        zs_soft[1].zs_next = 0;

        for(chip = 0; chip < NUM_SERIAL; chip++) {
                /* If we are doing kgdb over one of the channels on
                 * chip zero, kgdb_channel will be set to 1 by the
                 * rs_kgdb_hook() routine below.
                 */
                if(!zs_chips[chip]) {
                        zs_chips[chip] = get_zs(chip);
                        /* Two channels per chip */
                        zs_channels[(chip*2)] = &zs_chips[chip]->channelB;
                        zs_channels[(chip*2)+1] = &zs_chips[chip]->channelA;
                        zs_soft[(chip*2)].kgdb_channel = 0;
                        zs_soft[(chip*2)+1].kgdb_channel = 0;
                }
                /* First, set up channel A on this chip. */
                channel = chip * 2;
                zs_soft[channel].zs_channel = zs_channels[channel];
                zs_soft[channel].change_needed = 0;
                zs_soft[channel].clk_divisor = 16;
                zs_soft[channel].zs_baud = get_zsbaud(&zs_soft[channel]);
                zs_soft[channel].cons_mouse = 0;
                /* If not keyboard/mouse and is console serial
                 * line, then enable receiver interrupts.
                 */
                if(zs_soft[channel].is_cons) {
                        write_zsreg(zs_soft[channel].zs_channel, R1,
                                    (EXT_INT_ENAB | INT_ALL_Rx));
                        write_zsreg(zs_soft[channel].zs_channel, R9, (NV | MIE));
                        write_zsreg(zs_soft[channel].zs_channel, R10, (NRZ));
                        write_zsreg(zs_soft[channel].zs_channel, R3, (Rx8|RxENABLE));
                        write_zsreg(zs_soft[channel].zs_channel, R5, (Tx8 | TxENAB));
                }
                /* If this is the kgdb line, enable interrupts because we
                 * now want to receive the 'control-c' character from the
                 * client attached to us asynchronously.
                 */
                if(zs_soft[channel].kgdb_channel)
                        kgdb_chaninit(&zs_soft[channel], 1,
                                      zs_soft[channel].zs_baud);

                /* Now, channel B */
                channel++;
                zs_soft[channel].zs_channel = zs_channels[channel];
                zs_soft[channel].change_needed = 0;
                zs_soft[channel].clk_divisor = 16;
                zs_soft[channel].zs_baud = get_zsbaud(&zs_soft[channel]);
                zs_soft[channel].cons_keyb = 0;
                /* If console serial line, then enable receiver interrupts. */
                if(zs_soft[channel].is_cons) {
                        write_zsreg(zs_soft[channel].zs_channel, R1,
                                    (EXT_INT_ENAB | INT_ALL_Rx));
                        write_zsreg(zs_soft[channel].zs_channel, R9,
                                    (NV | MIE));
                        write_zsreg(zs_soft[channel].zs_channel, R10,
                                    (NRZ));
                        write_zsreg(zs_soft[channel].zs_channel, R3,
                                    (Rx8|RxENABLE));
                        write_zsreg(zs_soft[channel].zs_channel, R5,
                                    (Tx8 | TxENAB | RTS | DTR));
                }
        }

        for(info=zs_chain, i=0; info; info = info->zs_next, i++)
        {
                info->magic = SERIAL_MAGIC;
                info->port = (int) info->zs_channel;
                info->line = i;
                info->tty = 0;
                info->irq = zilog_irq;
                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;
                info->tqueue.routine = do_softint;
                info->tqueue.data = info;
                info->tqueue_hangup.routine = do_serial_hangup;
                info->tqueue_hangup.data = info;
                info->callout_termios =callout_driver.init_termios;
                info->normal_termios = serial_driver.init_termios;
                init_waitqueue_head(&info->open_wait);
                init_waitqueue_head(&info->close_wait);
                printk("tty%02d at 0x%04x (irq = %d)", info->line, 
                       info->port, info->irq);
                printk(" is a Zilog8530\n");
        }

        if (request_irq(zilog_irq, rs_interrupt, (SA_INTERRUPT),
                        "Zilog8530", zs_chain))
                panic("Unable to attach zs intr\n");
        restore_flags(flags);

        return 0;
}

/*
 * register_serial and unregister_serial allows for serial ports to be
 * configured at run-time, to support PCMCIA modems.
 */
/* SGI: 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;
}

/* Hooks for running a serial console.  con_init() calls this if the
 * console is being run over one of the ttya/ttyb serial ports.
 * 'chip' should be zero, as chip 1 drives the mouse/keyboard.
 * 'channel' is decoded as 0=TTYA 1=TTYB, note that the channels
 * are addressed backwards, channel B is first, then channel A.
 */
void
rs_cons_hook(int chip, int out, int line)
{
        int channel;

        
        if(chip)
                panic("rs_cons_hook called with chip not zero");
        if(line != 0 && line != 1)
                panic("rs_cons_hook called with line not ttya or ttyb");
        channel = line;
        if(!zs_chips[chip]) {
                zs_chips[chip] = get_zs(chip);
                /* Two channels per chip */
                zs_channels[(chip*2)] = &zs_chips[chip]->channelB;
                zs_channels[(chip*2)+1] = &zs_chips[chip]->channelA;
        }
        zs_soft[channel].zs_channel = zs_channels[channel];
        zs_soft[channel].change_needed = 0;
        zs_soft[channel].clk_divisor = 16;
        zs_soft[channel].zs_baud = get_zsbaud(&zs_soft[channel]);
        if(out) 
                zs_cons_chanout = ((chip * 2) + channel);
        else 
                zs_cons_chanin = ((chip * 2) + channel);
        
        rs_cons_check(&zs_soft[channel], channel);
}

/* This is called at boot time to prime the kgdb serial debugging
 * serial line.  The 'tty_num' argument is 0 for /dev/ttyd2 and 1 for
 * /dev/ttyd1 (yes they are backwards on purpose) which is determined
 * in setup_arch() from the boot command line flags.
 */
void
rs_kgdb_hook(int tty_num)
{
        int chip = 0;

        if(!zs_chips[chip]) {
                zs_chips[chip] = get_zs(chip);
                /* Two channels per chip */
                zs_channels[(chip*2)] = &zs_chips[chip]->channelA;
                zs_channels[(chip*2)+1] = &zs_chips[chip]->channelB;
        }
        zs_soft[tty_num].zs_channel = zs_channels[tty_num];
        zs_kgdbchan = zs_soft[tty_num].zs_channel;
        zs_soft[tty_num].change_needed = 0;
        zs_soft[tty_num].clk_divisor = 16;
        zs_soft[tty_num].zs_baud = get_zsbaud(&zs_soft[tty_num]);
        zs_soft[tty_num].kgdb_channel = 1;     /* This runs kgdb */
        zs_soft[tty_num ^ 1].kgdb_channel = 0; /* This does not */

        /* Turn on transmitter/receiver at 8-bits/char */
        kgdb_chaninit(&zs_soft[tty_num], 0, 9600);
        ZS_CLEARERR(zs_kgdbchan);
        udelay(5);
        ZS_CLEARFIFO(zs_kgdbchan);
}

static void zs_console_write(struct console *co, const char *str, unsigned int count)
{

        while(count--) {
                if(*str == '\n')
                        rs_put_char('\r');
                rs_put_char(*str++);
        }

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

static int zs_console_wait_key(struct console *con)
{
        sleep_on(&keypress_wait);
        return 0;
}

static kdev_t zs_console_device(struct console *con)
{
        return MKDEV(TTY_MAJOR, 64 + con->index);
}


static int __init zs_console_setup(struct console *con, char *options)
{
        struct sgi_serial *info;
        int     baud = 9600;
        int     bits = 8;
        int     parity = 'n';
        int     cflag = CREAD | HUPCL | CLOCAL;
        char    *s;
        int     i, brg;
    
        if (options) {
                baud = simple_strtoul(options, NULL, 10);
                s = options;
                while(*s >= '0' && *s <= '9')
                        s++;
                if (*s) parity = *s++;
                if (*s) bits   = *s - '0';
        }

        /*
         *      Now construct a cflag setting.
         */
        switch(baud) {
                case 1200:
                        cflag |= B1200;
                        break;
                case 2400:
                        cflag |= B2400;
                        break;
                case 4800:
                        cflag |= B4800;
                        break;
                case 19200:
                        cflag |= B19200;
                        break;
                case 38400:
                        cflag |= B38400;
                        break;
                case 57600:
                        cflag |= B57600;
                        break;
                case 115200:
                        cflag |= B115200;
                        break;
                case 9600:
                default:
                        cflag |= B9600;
                        break;
        }
        switch(bits) {
                case 7:
                        cflag |= CS7;
                        break;
                default:
                case 8:
                        cflag |= CS8;
                        break;
        }
        switch(parity) {
                case 'o': case 'O':
                        cflag |= PARODD;
                        break;
                case 'e': case 'E':
                        cflag |= PARENB;
                        break;
        }
        con->cflag = cflag;

        rs_cons_hook(0, 0, con->index);
        info = zs_soft + con->index;
        info->is_cons = 1;
    
        printk("Console: ttyS%d (Zilog8530)\n", info->line);

        i = con->cflag & CBAUD;
        if (con->cflag & CBAUDEX) {
                i &= ~CBAUDEX;
                con->cflag &= ~CBAUDEX;
        }
        info->zs_baud = baud;

        switch (con->cflag & CSIZE) {
                case CS5:
                        zscons_regs[3] = Rx5 | RxENABLE;
                        zscons_regs[5] = Tx5 | TxENAB;
                        break;
                case CS6:
                        zscons_regs[3] = Rx6 | RxENABLE;
                        zscons_regs[5] = Tx6 | TxENAB;
                        break;
                case CS7:
                        zscons_regs[3] = Rx7 | RxENABLE;
                        zscons_regs[5] = Tx7 | TxENAB;
                        break;
                default:
                case CS8:
                        zscons_regs[3] = Rx8 | RxENABLE;
                        zscons_regs[5] = Tx8 | TxENAB;
                        break;
        }
        zscons_regs[5] |= DTR;

        if (con->cflag & PARENB)
                zscons_regs[4] |= PAR_ENA;
        if (!(con->cflag & PARODD))
                zscons_regs[4] |= PAR_EVEN;

        if (con->cflag & CSTOPB)
                zscons_regs[4] |= SB2;
        else
                zscons_regs[4] |= SB1;

        brg = BPS_TO_BRG(baud, ZS_CLOCK / info->clk_divisor);
        zscons_regs[12] = brg & 0xff;
        zscons_regs[13] = (brg >> 8) & 0xff;
        memcpy(info->curregs, zscons_regs, sizeof(zscons_regs));
        memcpy(info->pendregs, zscons_regs, sizeof(zscons_regs));    
        load_zsregs(info->zs_channel, zscons_regs);
        ZS_CLEARERR(info->zs_channel);
        ZS_CLEARFIFO(info->zs_channel);
        return 0;
}

static struct console sgi_console_driver = {
        "ttyS",
        zs_console_write,       /* write */
        NULL,                   /* read */
        zs_console_device,      /* device */
        zs_console_wait_key,    /* wait_key */
        NULL,                   /* unblank */
        zs_console_setup,       /* setup */
        CON_PRINTBUFFER,
        -1,
        0,
        NULL
};

/*
 *      Register console.
 */
long __init serial_console_init(long kmem_start, long kmem_end)
{
        register_console(&sgi_console_driver);
        return kmem_start;
}