Import of Linux/MIPS 2.1.14.2

1 files changed, 2014 insertions, 0 deletions

diff --git a/drivers/sgi/char/sgiserial.c b/drivers/sgi/char/sgiserial.c
new file mode 100644
index 000000000..5e346359c
--- /dev/null
+++ b/drivers/sgi/char/sgiserial.c
@@ -0,0 +1,2014 @@
+/* sgiserial.c: Serial port driver for SGI machines.
+ *
+ * Copyright (C) 1996 David S. Miller (dm@engr.sgi.com)
+ */
+
+#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 <asm/io.h>
+#include <asm/irq.h>
+#include <asm/sgialib.h>
+#include <asm/system.h>
+#include <asm/segment.h>
+#include <asm/bitops.h>
+#include <asm/sgihpc.h>
+#include <asm/sgint23.h>
+
+#include "sgiserial.h"
+
+#define NUM_SERIAL 1     /* One chip on board. */
+#define NUM_CHANNELS (NUM_SERIAL * 2)
+
+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;
+int zs_nodes[NUM_SERIAL] = { 0, };
+
+struct sgi_serial zs_soft[NUM_CHANNELS];
+struct sgi_serial *zs_chain;  /* IRQ servicing chain */
+static int zilog_irq = 21;
+
+struct tty_struct zs_ttys[NUM_CHANNELS];
+/** struct tty_struct *zs_constty; **/
+
+/* 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 */
+};
+
+#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 struct semaphore tmp_buf_sem = MUTEX;
+
+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.
+ */
+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;
+	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;
+	junk = ioc_icontrol->istat0;
+	udelay(1);
+	channel->control = value;
+	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/16);
+	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_irq_off(&info->tqueue, &tq_serial);
+	mark_bh(SERIAL_BH);
+}
+
+extern void breakpoint(void);  /* For the KGDB frame character */
+
+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) {
+			show_buffers();
+			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.
+	 */
+	if((info->kgdb_channel) && (ch =='\003')) {
+		/* breakpoint(); */
+		goto clear_and_exit;
+	}
+
+	if(!tty)
+		goto clear_and_exit;
+
+	if (tty->flip.count >= TTY_FLIPBUF_SIZE)
+		queue_task_irq_off(&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_irq_off(&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_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 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);
+	}
+
+	info=info->zs_next;
+
+	/* 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);
+	}
+}
+
+/*
+ * -------------------------------------------------------------------
+ * 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 (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.
+ */
+void 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);
+}
+
+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;
+}
+
+/*
+ * zs_console_print is registered for printk.
+ */
+static void zs_console_print(const char *p)
+{
+	char c;
+
+	while((c=*(p++)) != 0) {
+		if(c == '\n')
+			rs_put_char('\r');
+		rs_put_char(c);
+	}
+
+	/* Comment this if you want to have a strict interrupt-driven output */
+	rs_fair_output();
+}
+
+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);
+}
+
+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);
+			memcpy_fromfs(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);
+}
+
+/*
+ * ------------------------------------------------------------
+ * 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;
+	memcpy_tofs(retinfo,&tmp,sizeof(*retinfo));
+	return 0;
+}
+
+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;
+	memcpy_fromfs(&new_serial,new_info,sizeof(new_serial));
+	old_info = *info;
+
+	if (!suser()) {
+		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();
+	put_user(status,value);
+	return 0;
+}
+
+/*
+ * 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;
+	current->timeout = jiffies + duration;
+	cli();
+	write_zsreg(info->zs_channel, 5, (info->curregs[5] | SND_BRK));
+	schedule();
+	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_fs_long(C_CLOCAL(tty) ? 1 : 0,
+				    (unsigned long *) arg);
+			return 0;
+		case TIOCSSOFTCAR:
+			arg = get_fs_long((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 sgi_serial));
+			if (error)
+				return error;
+			memcpy_tofs((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;
+			current->timeout = jiffies + info->close_delay;
+			schedule();
+		}
+		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)
+{
+	struct wait_queue wait = { current, NULL };
+	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();
+		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 (current->signal & ~current->blocked) {
+			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);
+
+}
+
+extern void register_console(void (*proc)(const char *));
+
+static inline void
+rs_cons_check(struct sgi_serial *ss, int channel)
+{
+	int i, o, io;
+	static consout_registered = 0;
+	static 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;
+
+	/* Register the console output putchar, if necessary */
+	if((zs_cons_chanout == channel)) {
+		o = 1;
+		/* double whee.. */
+		if(!consout_registered) {
+			register_console(zs_console_print);
+			consout_registered = 1;
+		}
+	}
+
+	/* 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]->channelA;
+			zs_channels[(chip*2)+1] = &zs_chips[chip]->channelB;
+			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;
+		info->open_wait = 0;
+		info->close_wait = 0;
+		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 != 1 && line != 2)
+		panic("rs_cons_hook called with line not ttya or ttyb");
+	channel = line - 1;
+	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[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);
+}