#include <linux/autoconf.h>	/* fastest method */
#ifdef CONFIG_SCC

#define RCS_ID "$Id: scc.c,v 1.17 1995/03/15 23:28:12 JReuter Exp JReuter $"

#define BANNER "Z8530 SCC driver v1.8.dl1bke (beta) by dl1bke\n"

/* ******************************************************************** */
/* *   SCC.C - Linux driver for Z8530 based HDLC cards for AX.25      *	*/ 
/* ******************************************************************** */

/* ********************************************************************

	(c) 1995 by Joerg Reuter DL1BKE

	portions (c) 1994 Hans Alblas PE1AYX 
	and      (c) 1993 Guido ten Dolle PE1NNZ

	for the complete copyright notice see >> Copying.Z8530DRV <<

   ********************************************************************	*/   

/*

   940913	- started to rewrite the drive
   950131	- changed copyright notice to GPL without limitations.
   950228	- (hopefully) fixed the reason for kernel panics in
                  chk_rcv_queue() [stupid error]
   950304       - fixed underrun/zcount handling
   950305	- the driver registers port addresses now
   950314	- fixed underrun interrupt handling again
   
   Thanks to:
   
   PE1CHL Rob	- for a lot of good ideas from his SCC driver for DOS
   PE1NNZ Guido - for his port of the original driver to Linux
   KA9Q   Phil  - from whom we stole the mbuf-structure
   PA3AYX Hans  - who rewrote the memory management and some minor,
                  but nevertheless useful changes
   DL8MBT Flori - for support
   DG0FT  Rene  - for the BayCom USCC support
   PA3AOU Harry - for ESCC testing, information supply and support
   
   PE1KOX Rob, DG1RTF Thomas, ON5QK Roland, 
   
   and all who sent me bug reports and ideas... 
   
   
   NB -- if you find errors, change something, please let me know
      	 first before you distribute it... And please don't touch
   	 the version number. Just replace my callsign in
   	 "v1.8.dl1bke" with your own. Just to avoid confusion...
   	  
   Jörg Reuter DL1BKE
   
*/


#include <linux/errno.h>
#include <linux/signal.h>
#include <linux/sched.h>
#include <linux/timer.h>
#include <linux/tqueue.h>
#include <linux/tty.h>
#include <linux/tty_driver.h>
#include <linux/tty_flip.h>
#include <linux/major.h>
#include <linux/termios.h>
#include <linux/serial.h>
#include <linux/interrupt.h>
#include <linux/ioport.h>
#include <linux/config.h>
#include <linux/string.h>
#include <linux/fcntl.h>
#include <linux/ptrace.h>
#include <linux/malloc.h>
#include <linux/scc.h>
#include <linux/delay.h>
#include "scc_config.h"

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

#include <stdlib.h>
#include <stdio.h>
#include <ctype.h>
#include <time.h>
#include <linux/kernel.h>


long scc_init(long kmem_start);

int scc_open(struct tty_struct *tty, struct file *filp);
static void scc_close(struct tty_struct *tty, struct file *filp);
int scc_write(struct tty_struct *tty, int from_user, unsigned char *buf, int count);
static void scc_put_char(struct tty_struct *tty, unsigned char ch);
static void scc_flush_chars(struct tty_struct *tty);
static int scc_write_room(struct tty_struct *tty);
static int scc_chars_in_buffer(struct tty_struct *tty);
static void scc_flush_buffer(struct tty_struct *tty);
static int scc_ioctl(struct tty_struct *tty, struct file *file, unsigned int cmd, unsigned long arg);
static void scc_set_termios(struct tty_struct *tty, struct termios *old_termios);
static void scc_throttle(struct tty_struct *tty);
static void scc_unthrottle(struct tty_struct *tty);
static void scc_start(struct tty_struct *tty);
static void scc_stop(struct tty_struct *tty);

static void z8530_init(void);

static void scc_change_speed(struct scc_channel *scc);
static void kiss_encode(struct scc_channel *scc);

static void init_channel(struct scc_channel *scc);
static void scc_key_trx (struct scc_channel *scc, char tx);
static void scc_txint(register struct scc_channel *scc);
static void scc_exint(register struct scc_channel *scc);
static void scc_rxint(register struct scc_channel *scc);
static void scc_spint(register struct scc_channel *scc);
static void scc_isr(int irq, struct pt_regs *regs);
static void scc_timer(void);
static void scc_init_timer(struct scc_channel *scc);

/* from serial.c */

static int baud_table[] = {
	0, 50, 75, 110, 134, 150, 200, 300, 600, 1200, 1800, 2400, 4800,
	9600, 19200, 38400, 57600, 115200, 0 };


struct tty_driver scc_driver;		    /* new in 1.1.xx */
static int scc_refcount;
static struct tty_struct *scc_table[2*MAXSCC];
static struct termios scc_termios[2 * MAXSCC];
static struct termios scc_termios_locked[2 * MAXSCC];
	
struct scc_channel SCC_Info[2 * MAXSCC];         /* information per channel */

unsigned char Random = 0;		/* random number for p-persist */
unsigned char Driver_Initialized = 0;
static struct sccbuf *sccfreelist[MAX_IBUFS] = {0};
static int allocated_ibufs = 0;


/* ******************************************************************** */
/* *			Port Access Functions			      * */
/* ******************************************************************** */

static inline unsigned char
InReg(register io_port port, register unsigned char reg)
{
#ifdef SCC_LDELAY
	register unsigned char r;
	Outb(port, reg);
	udelay(5);
	r=Inb(port);
	udelay(5);
	return r;
#else
	Outb(port, reg);
	return Inb(port);
#endif
}

static inline void
OutReg(register io_port port, register unsigned char reg, register unsigned char val)
{
#ifdef SCC_LDELAY
	Outb(port, reg); udelay(5);
	Outb(port, val); udelay(5);
#else
	Outb(port, reg);
	Outb(port, val);
#endif
}

static inline void
wr(register struct scc_channel *scc, register unsigned char reg, register unsigned char val)
{
	OutReg(scc->ctrl, reg, (scc->wreg[reg] = val));
}

static inline void
or(register struct scc_channel *scc, register unsigned char reg, register unsigned char val)
{
	OutReg(scc->ctrl, reg, (scc->wreg[reg] |= val));
}

static inline void
cl(register struct scc_channel *scc, register unsigned char reg, register unsigned char val)
{
	OutReg(scc->ctrl, reg, (scc->wreg[reg] &= ~val));
}

/* ******************************************************************** */
/* * 			Memory Buffer Management			*/
/* ******************************************************************** */

/* mbuf concept lent from KA9Q. Tnx PE1AYX for the buffer pool concept	*/
/* (sorry, do you have any better ideas?) */


/* allocate memory for the interrupt buffer pool */

void scc_alloc_buffer_pool(void)
{
	int i;
	struct sccbuf *sccb;
	struct mbuf   *bp;
	
   	for (i = 0 ; i < MAX_IBUFS ; i++)
   	{
   		sccb = (struct sccbuf *)kmalloc(sizeof(struct sccbuf), GFP_ATOMIC);
   		bp = (struct mbuf *)kmalloc(sizeof(struct mbuf), GFP_ATOMIC);
   		
		if ( !(sccb && bp) )
		{
			allocated_ibufs = --i;
			
			if (allocated_ibufs < 0)
				panic("scc_alloc_buffer_pool() - can't get buffer space");
			else
				printk("Warning: scc_alloc_buffer_pool() - allocated only %i buffers\n",i);
				
			return;
		}
		
		sccfreelist[i] = sccb;
		sccfreelist[i]->bp = bp;
		memset(sccfreelist[i]->bp ,0,sizeof(struct mbuf));
		sccfreelist[i]->inuse = 0;
		sccfreelist[i]->bp->type = 0;
		sccfreelist[i]->bp->refcnt = 0;
		sccfreelist[i]->bp->size = BUFSIZE;
	}
	allocated_ibufs = MAX_IBUFS;
}

unsigned int scc_count_used_buffers(unsigned int * rx, unsigned int * tx)
{
	unsigned int i, used = 0;
	
	if (rx) *rx = 0;
	if (tx) *tx = 0;
	
	for (i = 0 ; i < allocated_ibufs ; i++)
	{
		if (sccfreelist[i]->inuse)
		{
			switch (sccfreelist[i]->bp->type)
			{
				case BT_RECEIVE:
					if (rx) (*rx)++; break;
				case BT_TRANSMIT:
					if (tx) (*tx)++; break;
			}
			
			used++;
		}
	}
	
	return used;
}


/* Allocate mbuf */
struct mbuf *
scc_get_buffer(char type)
{
	int i;
	unsigned long flags;

	save_flags(flags); cli();	/* just to be sure */

	for (i = 0 ; i < allocated_ibufs ; i++)
	{
		if(sccfreelist[i]->inuse == 0)
		{
			sccfreelist[i]->inuse = 1;
			sccfreelist[i]->bp->type = type;
			sccfreelist[i]->bp->next = NULLBUF;
			sccfreelist[i]->bp->anext = NULLBUF;
			sccfreelist[i]->bp->dup = NULLBUF;
			sccfreelist[i]->bp->size = BUFSIZE;
			sccfreelist[i]->bp->refcnt = 1;
			sccfreelist[i]->bp->cnt = 0;
			sccfreelist[i]->bp->in_use = 0;
		
			restore_flags(flags);
			return sccfreelist[i]->bp;
		}
	}
	
	printk("\nSCC scc_get_buffer(): buffer pool empty\n");	/* should never happen */
	restore_flags(flags);
	return NULLBUF;
}


/* Decrement the reference pointer in an mbuf. If it goes to zero,
 * free all resources associated with mbuf.
 * Return pointer to next mbuf in packet chain
 */
struct mbuf *
scc_return_buffer(register struct mbuf *bp, char type)
{
	struct mbuf *bpnext;
	int i;
	unsigned long flags;
	
	if(!bp)
		return NULLBUF;
		
	save_flags(flags); cli();
	bpnext = bp->next;
	
	if (bp->dup)
	{
		for(i = 0 ; i < allocated_ibufs ; i++)
		{
			if(sccfreelist[i]->bp == bp->dup)
			{
			      if (sccfreelist[i]->bp->type != type)
			      {
			      	   printk("scc_return_buffer(bp->dup, %i): wrong buffer type %i",
			      	   	  type,sccfreelist[i]->bp->type);
			      }
			      
			      sccfreelist[i]->bp->cnt = 0;
			      sccfreelist[i]->bp->refcnt = 0;
			      sccfreelist[i]->bp->in_use = 0;
			      sccfreelist[i]->inuse = 0;
			      bp->dup = NULLBUF;
			}
		}
	}
	
	/* Decrement reference count. If it has gone to zero, free it. */
	if(--bp->refcnt <= 0)
	{
		for(i = 0 ; i < allocated_ibufs ; i++)
		{
			if(sccfreelist[i]->bp == bp)
			{
				if (sccfreelist[i]->bp->type != type)
				{
					printk("scc_return_buffer(bp, %i): wrong buffer type %i",
						type,sccfreelist[i]->bp->type);
				}				
			     
				sccfreelist[i]->bp->cnt = 0;
				sccfreelist[i]->bp->refcnt = 0;
				sccfreelist[i]->inuse = 0;
				restore_flags(flags);
				return bpnext;
			}
		}
	}
		
	printk("\nscc_return_buffer(): bogus pointer %p\n",bp);
	restore_flags(flags);
	return bpnext;
} 


/* Free packet (a chain of mbufs). Return pointer to next packet on queue,
 * if any
 */
struct mbuf *
scc_free_chain(register struct mbuf *bp, char type)
{
	register struct mbuf *abp;
	unsigned long flags;

	if(!bp) 
		return NULLBUF;
		
	save_flags(flags); cli();	
	
	abp = bp->anext;
	while (bp) bp = scc_return_buffer(bp, type);
		
	restore_flags(flags); cli();
	return abp;
}


/* Append mbuf to end of mbuf chain */
void
scc_append_to_chain(struct mbuf **bph,struct mbuf *bp)
{
	register struct mbuf *p;
	unsigned long flags;

	if(bph == NULLBUFP || bp == NULLBUF)
		return;
	
	save_flags(flags); cli();
	
	if(*bph == NULLBUF)
	{
		/* First one on chain */
		*bph = bp;
	} else {
		for(p = *bph ; p->next != NULLBUF ; p = p->next)
			;
		p->next = bp;
	}
	
	restore_flags(flags);
}


/* Append packet (chain of mbufs) to end of packet queue */
void
scc_enqueue(struct mbuf **queue,struct mbuf *bp)
{
	register struct mbuf *p;
	unsigned long flags;

	if(queue == NULLBUFP || bp == NULLBUF)
		return;
		
	save_flags(flags); cli();
	
	if(*queue == NULLBUF)
	{
		/* List is empty, stick at front */
		*queue = bp;
	} else {
		for(p = *queue ; p->anext != NULLBUF ; p = p->anext)
			;
		p->anext = bp;
	}
	restore_flags(flags);
}


/* ******************************************************************** */
/* *			Interrupt Service Routines		      * */
/* ******************************************************************** */

/* ----> interrupt service routine for the 8530 <---- */

/* it's recommendet to keep this function "inline" ;-) */

static inline void
scc_isr_dispatch(register struct scc_channel *scc, register int vector)
{
	switch (vector & VECTOR_MASK)
	{
		case TXINT: scc_txint(scc); break;
		case EXINT: scc_exint(scc); break;
		case RXINT: scc_rxint(scc); break;
		case SPINT: scc_spint(scc); break;
		default	  : printk("scc_isr(): unknown interrupt status (addr %4.4x, state %2.2x)\n",scc->ctrl,vector);
	}
}





/* If the card has a latch for the interrupt vector (like the PA0HZP card)
   use it to get the number of the chip that generated the int.
   If not: poll all defined chips.
 */

static void
scc_isr(int irq, struct pt_regs *regs)
{
	register unsigned char vector;	
	register struct scc_channel *scc;
	register io_port q;
	register io_port *p;
	register int k;


	cli();
	
	if (Vector_Latch)
	{
	    	while(1)			   /* forever...? */
    		{ 
			Outb(Vector_Latch, 0);      /* Generate INTACK */
        
			/* Read the vector */
			if((vector=Inb(Vector_Latch)) >= 16 * Nchips) break; 
						/* ...not forever! */
          
			/* Extract channel number and status from vector. */
			/* Isolate channel nummer */
			/* Call handler */
	        
			if (vector & 0x01) break; 
        	 
		        scc=&SCC_Info[(((vector>>1)&0x7c)^0x04) >> 2];
        
			if (!scc->tty) break;

			scc_isr_dispatch(scc, vector);
			
			Outb(scc->ctrl,0x38);              /* Reset Highest IUS" opcode to WR0 */
		}  
	    	
		sti();	
		return;
	}
	
	
	/* Find the SCC generating the interrupt by polling all attached SCCs
	 * reading RR3A (the interrupt pending register)
	 */

	k = 0;
	p = SCC_ctrl;
	
	while (k++ < Nchips)
	{
		if (!(q=*p++)) break;
		
		Outb(q,3);
		
		if (Inb(q))
		{
			if (!(q=*p++)) break;
			
			Outb(q,2);
			vector=Inb(q);                  /* Read the vector */
        
		        /* Extract channel number and status from vector. */
		        /* Isolate channel nummer */
		        /* Call handler */
        

			if (vector & 1) break; 
        
		        scc = &SCC_Info[(((vector >> 1) & 0x7c) ^ 0x04) >> 2];
        
		        if (!scc->tty) break;

			/* Isolate status info from vector, call handler */
			
			scc_isr_dispatch(scc, vector);

			k = 0;
			p = SCC_ctrl;

	     	} else p++;
	}    
	
	sti();
}



/* ----> four different interrupt handlers for Tx, Rx, changing of	*/
/*       DCD/CTS and Rx/Tx errors					*/


static inline void prepare_next_txframe(register struct scc_channel *scc)
{
	if ((scc->tbp = scc->sndq))
	{
		scc->sndq = scc->sndq->anext;
		scc->stat.tx_state = TXS_NEWFRAME;

	} else {
		scc->stat.tx_state = TXS_BUSY;
		scc->t_tail = scc->kiss.tailtime;
	}
}


/* Transmitter interrupt handler */
static void
scc_txint(register struct scc_channel *scc)
{
	register struct mbuf *bp;

	scc->stat.txints++;

	bp = scc->tbp;
			
	while (bp && !bp->cnt)      /* find next buffer */
		bp = scc_return_buffer(bp, BT_TRANSMIT);
				
	if (bp == NULLBUF)			/* no more buffers in this frame */
	{
		if (--scc->stat.tx_queued < 0)
			scc->stat.tx_queued = 0;
			
		Outb(scc->ctrl,RES_Tx_P);       /* reset pending int */					
		cl(scc,R10,ABUNDER);            /* frame complete, allow CRC transmit */ 
		prepare_next_txframe(scc);
		
	} else {				/* okay, send byte */
	
		if (scc->stat.tx_state == TXS_NEWFRAME)
		{				/* first byte ? */
			Outb(scc->ctrl, RES_Tx_CRC);	/* reset CRC generator */
			or(scc,R10,ABUNDER);		/* re-install underrun protection */
			Outb(scc->data,bp->data[bp->in_use++]);
							/* send byte */
			if (!scc->enhanced)		/* reset EOM latch */
				Outb(scc->ctrl, RES_EOM_L);
				
			scc->stat.tx_state = TXS_ACTIVE;/* next byte... */
		} else {
			Outb(scc->data,bp->data[bp->in_use++]);
		}
		
		bp->cnt--;                      /* decrease byte count */
		scc->tbp=bp;			/* store buffer address */
	}
}

/* Throw away received mbuf(s) when an error occurred */

static inline void
scc_toss_buffer(register struct scc_channel *scc)
{
	register struct mbuf *bp;
	
	if((bp = scc->rbp) != NULLBUF)
	{
		scc_free_chain(bp->next, BT_RECEIVE);
		bp->next = NULLBUF;
		scc->rbp1 = bp;         /* Don't throw this one away */
		bp->cnt = 0;            /* Simply rewind it */
		bp->in_use = 0;
	}
}

static inline void
flush_FIFO(register struct scc_channel *scc)
{
	register int k;
	
	for (k=0; k<3; k++)
		Inb(scc->data);
		
	if(scc->rbp != NULLBUF)	/* did we receive something? */
	{
		if(scc->rbp->next != NULLBUF || scc->rbp->cnt > 0)
			scc->stat.rxerrs++;  /* then count it as an error */
			
		scc_toss_buffer(scc);         /* throw away buffer */
	}
}



/* External/Status interrupt handler */
static void
scc_exint(register struct scc_channel *scc)
{
	register unsigned char status,changes,chg_and_stat;

	scc->stat.exints++;

	status = InReg(scc->ctrl,R0);
	changes = status ^ scc->status;
	chg_and_stat = changes & status;
	
	/* ABORT: generated whenever DCD drops while receiving */

	if (chg_and_stat & BRK_ABRT)		/* Received an ABORT */
		flush_FIFO(scc);
			
		
	/* DCD: on = start to receive packet, off = ABORT condition */
	/* (a successfully received packet generates a special condition int) */
	
	if(changes & DCD)                       /* DCD input changed state */
	{
		if(status & DCD)                /* DCD is now ON */
		{
			if (scc->modem.clocksrc != CLK_EXTERNAL)
				OutReg(scc->ctrl,R14,SEARCH|scc->wreg[R14]); /* DPLL: enter search mode */
				
			or(scc,R3,ENT_HM|RxENABLE); /* enable the receiver, hunt mode */
		} else {                        /* DCD is now OFF */
			cl(scc,R3,ENT_HM|RxENABLE); /* disable the receiver */
			flush_FIFO(scc);
		}
	}


	/* CTS: use external TxDelay (what's that good for?!) */
	
	if (chg_and_stat & CTS)			/* CTS is now ON */
	{			
		if (!Running(t_txdel) && scc->kiss.txdelay == 0) /* zero TXDELAY = wait for CTS */
			scc->t_txdel = 0;	/* kick it! */		
		
	}
	
	if ((scc->stat.tx_state == TXS_ACTIVE) && (status & TxEOM))
	{
		scc->stat.tx_under++;	  /* oops, an underrun! count 'em */
		Outb(scc->ctrl, RES_Tx_P);
		Outb(scc->ctrl, RES_EXT_INT);	/* reset ext/status interrupts */
		scc->t_maxk = 1;
		scc->tbp = scc_free_chain(scc->tbp, BT_TRANSMIT);
		
		if (--scc->stat.tx_queued < 0) scc->stat.tx_queued = 0;
		or(scc,R10,ABUNDER);
	}
		
	if (status & ZCOUNT)		   /* Oops? */
	{
		scc->stat.tx_under = 9999;  /* errr... yes. */
		Outb(scc->ctrl, RES_Tx_P); /* just to be sure */
		scc->t_maxk = 1;
		scc->tbp = scc_free_chain(scc->tbp, BT_TRANSMIT);
		if (--scc->stat.tx_queued < 0) scc->stat.tx_queued = 0;
		scc->kiss.tx_inhibit = 1;	/* don't try it again! */
	}
		
	
	scc->status = status;
	Outb(scc->ctrl,RES_EXT_INT);
}


/* Receiver interrupt handler */
static void
scc_rxint(register struct scc_channel *scc)
{
	register struct mbuf *bp;

	scc->stat.rxints++;

	if( Running(t_maxk) && !(scc->kiss.fulldup))
	{
		Inb(scc->data);		/* discard char */
		or(scc,R3,ENT_HM);	/* enter hunt mode for next flag */
		return;
	}

	if ((bp = scc->rbp1) == NULLBUF || bp->cnt >= bp->size)	
	{ 				/* no buffer available or buffer full */
		if (scc->rbp == NULLBUF)
		{
			if ((bp = scc_get_buffer(BT_RECEIVE)) != NULLBUF)
				scc->rbp = scc->rbp1 = bp;
				
		}
		else if ((bp = scc_get_buffer(BT_RECEIVE)))
		{
			scc_append_to_chain(&scc->rbp, bp);
			scc->rbp1 = bp;
		}
		
		if (bp == NULLBUF)		/* no buffer available? */
		{
			Inb(scc->data);		/* discard character */
			or(scc,R3,ENT_HM);      /* enter hunt mode */
			scc_toss_buffer(scc);	/* throw away buffers */
			scc->stat.nospace++;    /* and count this error */
			return;
		}
	}

	/* now, we have a buffer. read character and store it */
	bp->data[bp->cnt++] = Inb(scc->data);
}


/* Receive Special Condition interrupt handler */
static void
scc_spint(register struct scc_channel *scc)
{
	register unsigned char status;
	register struct mbuf *bp;

	scc->stat.spints++;

	status = InReg(scc->ctrl,R1);		/* read receiver status */
	
	Inb(scc->data);				/* throw away Rx byte */

	if(status & Rx_OVR)			/* receiver overrun */
	{
		scc->stat.rx_over++;                /* count them */
		or(scc,R3,ENT_HM);              /* enter hunt mode for next flag */
		scc_toss_buffer(scc);                 /* rewind the buffer and toss */
	}
	
	if(status & END_FR && scc->rbp != NULLBUF)	/* end of frame */
	{
		/* CRC okay, frame ends on 8 bit boundary and received something ? */
		
		if (!(status & CRC_ERR) && (status & 0xe) == RES8 && scc->rbp->cnt)
		{
			/* ignore last received byte (first of the CRC bytes) */
			
			for (bp = scc->rbp; bp->next != NULLBUF; bp = bp->next) ;
				bp->cnt--;              /* last byte is first CRC byte */
				
			scc_enqueue(&scc->rcvq,scc->rbp);
			scc->rbp = scc->rbp1 = NULLBUF;
			scc->stat.rxframes++;
			scc->stat.rx_queued++;
		} else {				/* a bad frame */
			scc_toss_buffer(scc);		/* throw away frame */
			scc->stat.rxerrs++;
		}
	}
	
	Outb(scc->ctrl,ERR_RES);
}


/* ******************************************************************** */
/* *			Init Channel					*/
/* ******************************************************************** */


/* ----> set SCC channel speed <---- */

static inline void set_brg(register struct scc_channel *scc, unsigned int tc)
{
	unsigned long flags;

 	save_flags(flags); cli();      	/* 2-step register accesses... */

	cl(scc,R14,BRENABL);		/* disable baudrate generator */
	wr(scc,R12,tc & 255);		/* brg rate LOW */
	wr(scc,R13,tc >> 8);   		/* brg rate HIGH */
	or(scc,R14,BRENABL);		/* enable baudrate generator */

	restore_flags(flags);
}

static inline void set_speed(register struct scc_channel *scc)
{
	set_brg(scc, (unsigned) (Clock / (scc->modem.speed * 64)) - 2);
}


/* ----> initialize a SCC channel <---- */

static inline void init_brg(register struct scc_channel *scc)
{
	wr(scc, R14, BRSRC);				/* BRG source = PCLK */
	OutReg(scc->ctrl, R14, SSBR|scc->wreg[R14]);	/* DPLL source = BRG */
	OutReg(scc->ctrl, R14, SNRZI|scc->wreg[R14]);	/* DPLL NRZI mode */
}

static void
init_channel(register struct scc_channel *scc)
{
	unsigned long flags;

	save_flags(flags); cli();

	wr(scc,R1,0);			/* no W/REQ operation */
	wr(scc,R3,Rx8|RxCRC_ENAB);	/* RX 8 bits/char, CRC, disabled */	
	wr(scc,R4,X1CLK|SDLC);		/* *1 clock, SDLC mode */
	wr(scc,R5,Tx8|DTR|TxCRC_ENAB);	/* TX 8 bits/char, disabled, DTR */
	wr(scc,R6,0);			/* SDLC address zero (not used) */
	wr(scc,R7,FLAG);		/* SDLC flag value */
	wr(scc,R9,VIS);			/* vector includes status */
	wr(scc,R10,(scc->modem.nrz? NRZ : NRZI)|CRCPS|ABUNDER); /* abort on underrun, preset CRC generator, NRZ(I) */
	wr(scc,R14, 0);


/* set clock sources:

   CLK_DPLL: normal halfduplex operation
   
		RxClk: use DPLL
		TxClk: use DPLL
		TRxC mode DPLL output
		
   CLK_EXTERNAL: external clocking (G3RUH or DF9IC modem)
   
  	        BayCom: 		others:
  	        
  	        TxClk = pin RTxC	TxClk = pin TRxC
  	        RxClk = pin TRxC 	RxClk = pin RTxC
  	     

   CLK_DIVIDER:
   		RxClk = use DPLL
   		TxClk = pin RTxC
   		
   		BayCom:			others:
   		pin TRxC = DPLL		pin TRxC = BRG
   		(RxClk * 1)		(RxClk * 32)
*/  

   		
	switch(scc->modem.clocksrc)
	{
		case CLK_DPLL:
			wr(scc, R11, RCDPLL|TCDPLL|TRxCOI|TRxCDP);
			init_brg(scc);
			break;

		case CLK_DIVIDER:
			wr(scc, R11, ((Board & BAYCOM)? TRxCDP : TRxCBR) | RCDPLL|TCRTxCP|TRxCOI);
			init_brg(scc);
			break;

		case CLK_EXTERNAL:
			wr(scc, R11, (Board & BAYCOM)? RCTRxCP|TCRTxCP : RCRTxCP|TCTRxCP);
			OutReg(scc->ctrl, R14, DISDPLL);
			break;

	}
	
	/* enable CTS (not for Baycom), ABORT & DCD interrupts */
	wr(scc,R15,((Board & BAYCOM) ? 0 : CTSIE)|BRKIE|DCDIE|TxUIE);

	if(scc->enhanced)
	{
		or(scc,R15,SHDLCE|FIFOE);	/* enable FIFO, SDLC/HDLC Enhancements (From now R7 is R7') */
		wr(scc,R7,AUTOEOM);
	}

	if((InReg(scc->ctrl,R0)) & DCD)		/* DCD is now ON */
	{
		if (scc->modem.clocksrc != CLK_EXTERNAL)
			or(scc,R14, SEARCH);
			
		or(scc,R3,ENT_HM|RxENABLE);	/* enable the receiver, hunt mode */
	}
	
	Outb(scc->ctrl,RES_EXT_INT);	/* reset ext/status interrupts */
	Outb(scc->ctrl,RES_EXT_INT);	/* must be done twice */
	
	scc->status = InReg(scc->ctrl,R0);	/* read initial status */

	or(scc,R1,INT_ALL_Rx|TxINT_ENAB|EXT_INT_ENAB); /* enable interrupts */
	or(scc,R9,MIE);			/* master interrupt enable */
			
	restore_flags(flags);
	
	set_speed(scc); 
}




/* ******************************************************************** */
/* *			SCC timer functions			      * */
/* ******************************************************************** */


/* ----> scc_key_trx sets the time constant for the baudrate 
         generator and keys the transmitter		     <---- */

static void
scc_key_trx(struct scc_channel *scc, char tx)
{
	unsigned int time_const;

	if (scc->modem.speed < baud_table[1]) 
		scc->modem.speed = 1200;
		
	if (Board & PRIMUS)
		Outb(scc->ctrl + 4, Option | (tx? 0x80 : 0));
	
	time_const = (unsigned) (Clock / (scc->modem.speed * (tx? 2:64))) - 2;
	
	if (scc->modem.clocksrc == CLK_DPLL)
	{				/* simplex operation */
		if (tx)
		{
			cl(scc,R3,RxENABLE|ENT_HM);	/* then switch off receiver */
			
			set_brg(scc, time_const);	/* reprogram baudrate generator */

			/* DPLL -> Rx clk, BRG -> Tx CLK, TRxC mode output, TRxC = BRG */
			wr(scc, R11, RCDPLL|TCBR|TRxCOI|TRxCBR);
			
			or(scc,R5,RTS|TxENAB);		/* set the RTS line and enable TX */
		} else {
			cl(scc,R5,RTS|TxENAB);
			
			set_brg(scc, time_const);	/* reprogram baudrate generator */
			
			/* DPLL -> Rx clk, DPLL -> Tx CLK, TRxC mode output, TRxC = DPLL */
			wr(scc, R11, RCDPLL|TCDPLL|TRxCOI|TRxCDP);
			
			or(scc,R3,RxENABLE|ENT_HM);
		}
	} else {
		if (tx)
			or(scc,R5,RTS|TxENAB);		/* enable tx */
		else
			cl(scc,R5,RTS|TxENAB);		/* disable tx */
	}
}


/* ----> SCC timer interrupt handler and friends. Will be called every 1/TPS s <---- */

static unsigned char Rand = 17;

static inline int is_grouped(register struct scc_channel *scc)
{
	int k;
	struct scc_channel *scc2;
	unsigned char grp1, grp2;

	grp1 = scc->kiss.group;
	
	for (k = 0; k < (Nchips * 2); k++)
	{
		scc2 = &SCC_Info[k];
		grp2 = scc2->kiss.group;
		
		if (scc2 == scc || !(scc2->tty && grp2)) 
			return 0;
		
		if (grp1 & 0x3f == grp2 & 0x3f)
		{
			if ( (grp1 & TXGROUP) && (scc2->wreg[R5] & RTS) )
				return 1;
			
			if ( (grp1 & RXGROUP) && (scc2->status & DCD) )
				return 1;
		}
	}
	return 0;
}
		

static inline void dw_slot_timeout(register struct scc_channel *scc)
{
	scc->t_dwait = TIMER_STOPPED;
	scc->t_slot = TIMER_STOPPED;
	
	if (!scc->kiss.fulldup)
	{
		Rand = Rand * 17 + 31;
		
		if ( (scc->kiss.softdcd? !(scc->status & SYNC_HUNT):(scc->status & DCD))  || (scc->kiss.persist) < Rand || (scc->kiss.group && is_grouped(scc)) )
		{
			if (scc->t_mbusy == TIMER_STOPPED)
				scc->t_mbusy = TPS * scc->kiss.maxdefer;
				
			scc->t_slot = scc->kiss.slottime;
			return ;
			
		}
	}
	
	if ( !(scc->wreg[R5] & RTS) )
	{
		scc->t_txdel = scc->kiss.txdelay;
		scc_key_trx(scc, TX_ON);
	} else {
		scc->t_txdel = 0;
	}
}




static inline void txdel_timeout(register struct scc_channel *scc)
{
	scc->t_txdel = TIMER_STOPPED;
	
	scc->t_maxk = TPS * scc->kiss.maxkeyup;
	prepare_next_txframe(scc);
	
	if (scc->stat.tx_state != TXS_BUSY)
		scc_txint(scc);		
}
	


static inline void tail_timeout(register struct scc_channel *scc)
{
	scc->t_tail = TIMER_STOPPED;
	
	/* when fulldup is 0 or 1, switch off the transmitter.
	 * when frames are still queued (because of transmit time limit),
	 * restart the procedure to get the channel after MINTIME.
	 * when fulldup is 2, the transmitter remains keyed and we
	 * continue sending after waiting for waittime. IDLETIME is an 
	 * idle timeout in this case.
	 */ 
	 
	 if (scc->kiss.fulldup < 2)
	 {
	 	if (scc->sndq)		/* we had a timeout? */
	 	{
	 		scc->stat.tx_state = TXS_BUSY;
	 		scc->t_dwait = TPS * scc->kiss.mintime; /* try again */
	 	}
	 	
	 	scc->stat.tx_state = TXS_IDLE;
		scc->t_maxk = TIMER_STOPPED;
	 	scc_key_trx(scc, TX_OFF);
	 	return;
	 }
	 
	 if (scc->sndq)			/* maxkeyup expired */ /* ?! */
	 {
	 	scc->stat.tx_state = TXS_BUSY;
	 	scc->t_txdel = TPS * scc->kiss.waittime;
	 }
	 else
	 
	 	scc->t_idle = TPS * scc->kiss.idletime;
}


static inline void busy_timeout(register struct scc_channel *scc)
{
#ifdef	THROW_AWAY_AFTER_BUSY_TIMEOUT
	register struct mbuf *bp;		/* not tested */

	bp = scc->sndq;
	
	while (bp) bp = scc_free_chain(bp, BT_TRANSMIT);
	
	scc->sndq = NULLBUF;
	scc->stat.tx_state = TXS_IDLE;
	
#else
	scc->t_txdel = scc->kiss.txdelay;	/* brute force ... */
#endif
	scc->t_mbusy = TIMER_STOPPED;
	
}


static inline void maxk_idle_timeout(register struct scc_channel *scc)
{
	scc->t_maxk = TIMER_STOPPED;
	scc->t_idle = TIMER_STOPPED;
	
	scc->stat.tx_state = TXS_BUSY;
	scc->t_tail = scc->kiss.tailtime;
}

static inline void check_rcv_queue(register struct scc_channel *scc)
{
	register struct mbuf *bp;
	
	if (scc->stat.rx_queued > QUEUE_THRES)
	{
		if (scc->rcvq == NULLBUF)
		{
			printk("z8530drv: Warning - scc->stat.rx_queued shows overflow"
			       " (%d) but queue is empty\n", scc->stat.rx_queued);
			       
			scc->stat.rx_queued = 0;	/* correct it */
			scc->stat.nospace = 12345;	/* draw attention to it */
			return;
		}
			
		bp = scc->rcvq->anext;	/* don't use the one we currently use */
		
		while (bp && (scc->stat.rx_queued > QUEUE_HYST))
		{
			bp = scc_free_chain(bp, BT_RECEIVE);
			scc->stat.rx_queued--;
			scc->stat.nospace++;
		}
		
		scc->rcvq->anext = bp;
	}
}

static void
scc_timer(void)
{
	register struct scc_channel *scc;
	register int chan;
	unsigned long flags;
		
	save_flags(flags); cli();
	
	for (chan = 0; chan < (Nchips * 2); chan++)
	{
		scc = &SCC_Info[chan];
		
		if (scc->tty && scc->init)
		{
			kiss_encode(scc);
			check_rcv_queue(scc);
			
			/* KISS-TNC emulation */
			
			if (Expired(t_dwait)) dw_slot_timeout(scc)	; else
			if (Expired(t_slot))  dw_slot_timeout(scc)	; else
			if (Expired(t_txdel)) txdel_timeout(scc)   	; else
			if (Expired(t_tail))  tail_timeout(scc)	   	;
			
			/* watchdogs */
			
			if (Expired(t_mbusy)) busy_timeout(scc);
			if (Expired(t_maxk))  maxk_idle_timeout(scc);
			if (Expired(t_idle))  maxk_idle_timeout(scc);
		}
	}
	
	timer_table[SCC_TIMER].fn = scc_timer;
	timer_table[SCC_TIMER].expires = jiffies + HZ/TPS;
	timer_active |= 1 << SCC_TIMER; 
	
	restore_flags(flags);
}
			

static void
scc_init_timer(struct scc_channel *scc)
{
	unsigned long flags;
	
	save_flags(flags); cli();
	
	Stop_Timer(t_dwait);
	Stop_Timer(t_slot);
	Stop_Timer(t_txdel);
	Stop_Timer(t_tail);
	Stop_Timer(t_mbusy);
	Stop_Timer(t_maxk);
	Stop_Timer(t_idle);
	scc->stat.tx_state = TXS_IDLE;
	
	restore_flags(flags);
}



/* ******************************************************************** */
/* *			KISS interpreter			      * */
/* ******************************************************************** */


/*
 * this will set the "kiss" parameters through kiss itself
 */
 
static void
kiss_set_param(struct scc_channel *scc,char cmd, unsigned int val)
{

#define  VAL val=val*TPS/100
#define SVAL val? val:TIMER_STOPPED

	switch(cmd){
	case PARAM_TXDELAY:
		scc->kiss.txdelay = VAL; break;
	case PARAM_PERSIST:
		scc->kiss.persist = val; break;
	case PARAM_SLOTTIME:
		scc->kiss.slottime = VAL; break;
	case PARAM_TXTAIL:
		scc->kiss.tailtime = VAL; break;
	case PARAM_FULLDUP:
		scc->kiss.fulldup = val; break;
	case PARAM_WAIT:
		scc->kiss.waittime = VAL; break;
	case PARAM_MAXKEY:
		scc->kiss.maxkeyup = SVAL; break;
	case PARAM_MIN:
		scc->kiss.mintime = SVAL; break;
	case PARAM_IDLE:
		scc->kiss.idletime = val; break;
	case PARAM_MAXDEFER:
		scc->kiss.maxdefer = SVAL; break;
	case PARAM_GROUP:
		scc->kiss.group = val;  break;
	case PARAM_TX:
		scc->kiss.tx_inhibit = val;
	case PARAM_SOFTDCD:
		scc->kiss.softdcd = val;
	}
	return;

#undef  VAL
#undef SVAL
}


/* interpret frame: strip CRC and decode KISS */

static void kiss_interpret_frame(struct scc_channel * scc)
{
	unsigned char kisscmd;
	unsigned long flags;

	if (scc->sndq1->cnt < 2)
	{
		if (scc->sndq1) 
			scc_free_chain(scc->sndq1, BT_TRANSMIT);
		else
			scc->sndq1 = NULLBUF;
			
		scc->sndq2 = NULLBUF;
		return;
	}
	
	
	
	if (scc->kiss.not_slip)
	{
		kisscmd = scc->sndq1->data[scc->sndq1->in_use++];
		scc->sndq1->cnt--;
	} else {
		kisscmd = 0;
	}

	if (kisscmd & 0xa0)
	{
		if (scc->sndq1->cnt > 2)
			scc->sndq1->cnt -= 2;
		else
		{
			scc_free_chain(scc->sndq1, BT_TRANSMIT);
			scc->sndq2 = NULLBUF;
			return;
		}
	}
	
	
	kisscmd &= 0x1f;
	
		
	if (kisscmd)
	{
		kiss_set_param(scc, kisscmd, scc->sndq1->data[scc->sndq1->in_use]);
		scc->sndq1->cnt=0;
		scc->sndq1->in_use=0;
					
		scc_free_chain(scc->sndq1, BT_TRANSMIT);
		scc->sndq2 = NULLBUF;
		return;
	}
	
	scc_enqueue(&scc->sndq,scc->sndq1); /* scc_enqueue packet */
	scc->stat.txframes++;
	scc->stat.tx_queued++;
	scc->sndq2 = NULLBUF;		/* acquire a new buffer next time */

	save_flags(flags); cli();

	if(scc->stat.tx_state == TXS_IDLE)
	{      				/* when transmitter is idle */
		scc_init_timer(scc);
		scc->stat.tx_state = TXS_BUSY;
		scc->t_dwait = (scc->kiss.fulldup? 0:scc->kiss.waittime);
	}
	
	restore_flags(flags);
}

static void kiss_store_byte(struct scc_channel *scc, unsigned char ch)
{
	if (scc->sndq2 == NULLBUF) return;
	
	if(scc->sndq2->cnt == scc->sndq2->size)		/* buffer full? */
	{
		if((scc->sndq2 = scc_get_buffer(BT_TRANSMIT)) == NULLBUF)
		{
			printk("\nsccdrv: running out of memory\n");
			return;
		}
		scc_append_to_chain(&scc->sndq1,scc->sndq2);         /* add buffer */
	}
	
	scc->sndq2->data[scc->sndq2->cnt++] = ch;
}

static inline int kiss_decode(struct scc_channel *scc, unsigned char ch)
{
	switch (scc->stat.tx_kiss_state) 
	{
		case KISS_IDLE:
			if (ch == FEND)
			{
				if (!(scc->sndq2 = scc->sndq1 = scc_get_buffer(BT_TRANSMIT)))
					return 0;
					
				scc->stat.tx_kiss_state = KISS_DATA;
			} else scc->stat.txerrs++;
			break;
					
		case KISS_DATA:
			if (ch == FESC)
				scc->stat.tx_kiss_state = KISS_ESCAPE;
			else if (ch == FEND)
			{
				kiss_interpret_frame(scc);	
				scc->stat.tx_kiss_state = KISS_IDLE;
			}
			else kiss_store_byte(scc, ch);
			break;
					
		case KISS_ESCAPE:
			if (ch == TFEND)
			{
				kiss_store_byte(scc, FEND);
				scc->stat.tx_kiss_state = KISS_DATA;
			}
			else if (ch == TFESC)
			{
				kiss_store_byte(scc, FESC);
				scc->stat.tx_kiss_state = KISS_DATA;
			}
			else
			{
				scc_free_chain(scc->sndq1, BT_TRANSMIT);
				scc->sndq2 = NULLBUF;
				scc->stat.txerrs++;
				scc->stat.tx_kiss_state = KISS_IDLE;
			}
			break;
	} /* switch */
	
	return 0;
	
}

/* ----> Encode received data and write it to the flip-buffer  <---- */

/* receive raw frame from SCC. used for AX.25 */
static void
kiss_encode(register struct scc_channel *scc)
{
	struct mbuf *bp,*bp2;
	struct tty_struct * tty = scc->tty;
	unsigned long flags; 
	unsigned char ch;

	if(!scc->rcvq)
	{
		scc->stat.rx_kiss_state = KISS_IDLE;
		return;
	}
	
	/* worst case: FEND 0 FESC TFEND -> 4 bytes */
	
	while(tty->flip.count < TTY_FLIPBUF_SIZE-3)
	{ 
		if (scc->rcvq->cnt)
		{
			bp = scc->rcvq;
			
			if (scc->stat.rx_kiss_state == KISS_IDLE)
			{
				tty_insert_flip_char(tty, FEND, 0);
				
				if (scc->kiss.not_slip)
					tty_insert_flip_char(tty, 0, 0);
					
				scc->stat.rx_kiss_state = KISS_RXFRAME;
			}
				
			switch(ch = bp->data[bp->in_use++])
			{
				case FEND:
					tty_insert_flip_char(tty, FESC, 0);
					tty_insert_flip_char(tty, TFEND, 0);
					break;
				case FESC:
					tty_insert_flip_char(tty, FESC, 0);
					tty_insert_flip_char(tty, TFESC, 0);
					break;
				default:
					tty_insert_flip_char(tty, ch, 0);
			}
			
			bp->cnt--;
			
 		} else {
			save_flags(flags); cli();
			
			while (!scc->rcvq->cnt)
	 		{				 /* buffer empty? */
				bp  = scc->rcvq->next;  /* next buffer */
				bp2 = scc->rcvq->anext; /* next packet */
				
				
				scc_return_buffer(scc->rcvq, BT_RECEIVE);
				
				if (!bp)	/* end of frame ? */
				{
					scc->rcvq = bp2;
					
					if (--scc->stat.rx_queued < 0)
						scc->stat.rx_queued = 0;
					
					if (scc->stat.rx_kiss_state == KISS_RXFRAME)	/* new packet? */
					{
						tty_insert_flip_char(tty, FEND, 0); /* send FEND for old frame */
						scc->stat.rx_kiss_state = KISS_IDLE; /* generate FEND for new frame */
					}
					
					restore_flags(flags);
					queue_task(&tty->flip.tqueue, &tq_timer);
					return;
					
				} else scc->rcvq = bp; /* next buffer */
			}
			
			restore_flags(flags);
		}						
		
	}
	
 	queue_task(&tty->flip.tqueue, &tq_timer); /* kick it... */
}


/* ******************************************************************* */
/* *		Init channel structures, special HW, etc...	     * */
/* ******************************************************************* */


static void
z8530_init(void)
{
	struct scc_channel *scc;
	int chip,chan;
	unsigned long flags;
    	int k;

	/* reset and pre-init all chips in the system */
	for (chip = 0; chip < Nchips; chip++)
	{
		/* Special SCC cards */

		if(Board & EAGLE)			/* this is an EAGLE card */
			Outb(Special_Port,0x08);	/* enable interrupt on the board */
			
		if(Board & (PC100 | PRIMUS))		/* this is a PC100/EAGLE card */
			Outb(Special_Port,Option);	/* set the MODEM mode (22H normally) */
			
		/* Init SCC */
		
		scc=&SCC_Info[2*chip];
		if (!scc->ctrl) continue;
		
		save_flags(flags); cli();
		
		Outb(scc->ctrl, 0);
		OutReg(scc->ctrl,R9,FHWRES);		/* force hardware reset */
		for (k=1; k < 1000; k++) ;
		
		for (chan = 0; chan < 2; chan++)
		{
			scc=&SCC_Info[2*chip+chan];
			
			wr(scc,R1, 0);
			wr(scc,R2, chip*16);		/* No of chip is vector */
			wr(scc,R9,VIS);			/* vector includes status */
		}
 
        	restore_flags(flags);
        }

	if (Ivec == 2) Ivec = 9;			/* this f... IBM AT-design! */
	request_irq(Ivec, scc_isr,   SA_INTERRUPT, "AX.25 SCC");
 
	Driver_Initialized = 1;
}


/* ******************************************************************** */
/* * 	Filesystem Routines: open, close, ioctl, settermios, etc      * */
/* ******************************************************************** */



/* scc_paranoia_check(): warn user if something went wrong		*/

static inline int scc_paranoia_check(struct scc_channel *scc, dev_t device, const char *routine)
{
#ifdef SCC_PARANOIA_CHECK
	static const char *badmagic =
		"Warning: bad magic number for Z8530 SCC struct (%d, %d) in %s\n";
        static const char *badinfo =
                "Warning: Z8530 not found for (%d, %d) in %s\n";
       
	if (!scc->init) 
	{
        	printk(badinfo, MAJOR(device), MINOR(device), routine);
                return 1;
        }
        if (scc->magic != SCC_MAGIC) {
        	printk(badmagic, MAJOR(device), MINOR(device), routine);
                return 1;
        }
#endif

	return 0;
}


/* ----> this one is called whenever you open the device <---- */

int scc_open(struct tty_struct *tty, struct file * filp)
{
	struct scc_channel *scc;
	int chan;
	
        chan = MINOR(tty->device) - tty->driver.minor_start;
        if ((chan < 0) || (chan >= (Nchips * 2)))
                return -ENODEV;
 
 	scc = &SCC_Info[chan];
 	
	tty->driver_data = scc;
 	tty->termios->c_cflag &= ~CBAUD; 
 	
	if (!Driver_Initialized)
		return 0;
	
	if (scc->magic != SCC_MAGIC)
	{
		printk("ERROR: scc_open(): bad magic number for device (%d, %d)", MAJOR(tty->device), MINOR(tty->device));
		return -ENODEV;
	}		
	
	if(scc->tty != NULL)
	{
		scc->tty_opened++;
		return 0;
	}

 	if(!scc->init) return 0;
 	 	 	 
  	scc->tty = tty;
	init_channel(scc);

	scc->stat.tx_kiss_state = KISS_IDLE;	/* don't change this... */
	scc->stat.rx_kiss_state = KISS_IDLE;	/* ...or this */
	
	scc_init_timer(scc);
	
	timer_table[SCC_TIMER].fn = scc_timer;
	timer_table[SCC_TIMER].expires = 0;	/* now! */
	timer_active |= 1 << SCC_TIMER;
	
	return 0;
}


/* ----> and this whenever you close the device <---- */

static void
scc_close(struct tty_struct *tty, struct file * filp)
{
	struct scc_channel *scc = tty->driver_data;
	unsigned long flags;

        if (!scc || (scc->magic != SCC_MAGIC))
                return;
	
	if(scc->tty_opened)
	{
		scc->tty_opened--;
		return;
	}
	
	tty->driver_data = NULLBUF;
	
	save_flags(flags); cli();
	
	Outb(scc->ctrl,0);		/* Make sure pointer is written */
	wr(scc,R1,0);			/* disable interrupts */
	wr(scc,R3,0);
	
	scc->tty = NULL;
	
	restore_flags(flags);
	tty->stopped = 0;		
}




/*
 * change scc_speed
 */
 
static void
scc_change_speed(struct scc_channel * scc)
{
	if (scc->tty == NULL)
		return;
		
	scc->modem.speed = baud_table[scc->tty->termios->c_cflag & CBAUD];
	
	if (scc->stat.tx_state == 0)	/* only switch baudrate on rx... ;-) */
		set_speed(scc);
}


/* ----> ioctl-routine of the driver <---- */

/* perform ioctl on SCC (sdlc) channel
 * this is used for AX.25 mode, and will set the "kiss" parameters
 */
 
/* TIOCMGET 	- get modem status	arg: (unsigned long *) arg
 * TIOCMBIS 	- set PTT		arg: ---
 * TIOCMBIC 	- reset PTT		arg: ---
 * TIOCMBIC 	- set PTT		arg: ---
 * TIOCSCCINI	- initialize driver	arg: ---
 * TIOCCHANINI	- initialize channel	arg: (struct scc_modem *) arg
 * TIOCGKISS	- get level 1 parameter	arg: (struct ioctl_command *) arg
 * TIOCSKISS	- set level 1 parameter arg: (struct ioctl_command *) arg
 * TIOCSCCSTAT  - get driver status	arg: (struct scc_stat *) arg
 */
 

static int
scc_ioctl(struct tty_struct *tty, struct file * file, unsigned int cmd, unsigned long arg)
{
	struct scc_channel * scc = tty->driver_data;
	unsigned long flags, r;
	unsigned int result;
	unsigned int value;
	struct ioctl_command kiss_cmd;
	int error;

        if (scc->magic != SCC_MAGIC) 
        {
		printk("ERROR: scc_ioctl(): bad magic number for device %d,%d", 
			MAJOR(tty->device), MINOR(tty->device));
			
                return -ENODEV;
        }
	                                                 
	r = NO_SUCH_PARAM;
	
	if (!Driver_Initialized)
	{
		if (cmd == TIOCSCCINI)
		{
			if (!suser())
				return -EPERM;
			
			scc_alloc_buffer_pool();
			z8530_init();
			return 0;
		}
		
		return -EINVAL;	/* confuse the user */
	}
	
	if (!scc->init)
	{

		if (cmd == TIOCCHANINI)
		{
			if (!arg)
				return -EFAULT;
				
			if (!suser())
				return -EPERM;
			
			memcpy_fromfs(&scc->modem, (void *) arg, sizeof(struct scc_modem));
			
			/* default KISS Params */
		
			if (scc->modem.speed < 4800)
			{
				scc->kiss.txdelay = 36*TPS/100;    /* 360 ms */
				scc->kiss.persist = 42;            /* 25% persistence */			/* was 25 */
				scc->kiss.slottime = 16*TPS/100;   /* 160 ms */
				scc->kiss.tailtime = 4;            /* minimal reasonable value */
				scc->kiss.fulldup = 0;             /* CSMA */
				scc->kiss.waittime = 50*TPS/100;   /* 500 ms */
				scc->kiss.maxkeyup = 10;           /* 10 s */
				scc->kiss.mintime = 3;             /* 3 s */
				scc->kiss.idletime = 30;           /* 30 s */
				scc->kiss.maxdefer = 120;	   /* 2 min */
				scc->kiss.not_slip = 1;		   /* KISS mode */
				scc->kiss.softdcd = 0;		   /* hardware dcd */
			} else {
				scc->kiss.txdelay = 10*TPS/100;    /* 100 ms */
				scc->kiss.persist = 64;            /* 25% persistence */			/* was 25 */
				scc->kiss.slottime = 8*TPS/100;    /* 160 ms */
				scc->kiss.tailtime = 1;            /* minimal reasonable value */
				scc->kiss.fulldup = 0;             /* CSMA */
				scc->kiss.waittime = 50*TPS/100;   /* 500 ms */
				scc->kiss.maxkeyup = 7;            /* 7 s */
				scc->kiss.mintime = 3;             /* 3 s */
				scc->kiss.idletime = 30;           /* 30 s */
				scc->kiss.maxdefer = 120;	   /* 2 min */
				scc->kiss.not_slip = 1;		   /* KISS mode */
				scc->kiss.softdcd = 0;		   /* hardware dcd */
			}
			
			scc->init = 1;			
			
			return 0;
		}
		
		return -EINVAL;
	}

	switch(cmd){
	case TCSBRK:
		return 0;
	case TIOCMGET:
		error = verify_area(VERIFY_WRITE, (void *) arg,sizeof(unsigned int *));
		if (error)
			return error;

		save_flags(flags); cli();
		
		result =  ((scc->wreg[R5] & RTS) ? TIOCM_RTS : 0)
			| ((scc->wreg[R5] & DTR) ? TIOCM_DTR : 0)
			| ((InReg(scc->ctrl,R0) & DCD)  ? TIOCM_CAR : 0)
			| ((InReg(scc->ctrl,R0) & CTS)  ? TIOCM_CTS : 0);
		
		restore_flags(flags);
			
		put_fs_long(result,(unsigned long *) arg);
		return 0;
	case TIOCMBIS:
	case TIOCMBIC:
	case TIOCMSET:
		switch (cmd) {
		case TIOCMBIS:
			scc->wreg[R5] |= DTR;
			scc->wreg[R5] |= RTS;
			break;
		case TIOCMBIC:
			scc->wreg[R5] &= ~DTR;
			scc->wreg[R5] &= ~RTS;
			break;
		case TIOCMSET:
			value = get_fs_long((unsigned long *) arg);
			
			if(value & TIOCM_DTR)
				scc->wreg[R5] |= DTR;
			else
				scc->wreg[R5] &= ~DTR;
			if(value & TIOCM_RTS)
				scc->wreg[R5] |= RTS;
			else
				scc->wreg[R5] &= ~RTS;
			break;
		}
		
		save_flags(flags); cli();
		
		if(scc->stat.tx_state == TXS_IDLE && !Running(t_idle))
			maxk_idle_timeout(scc);
			
		restore_flags(flags);
		
		return 0;
		
	case TCGETS:
		error = verify_area(VERIFY_WRITE, (void *) arg, sizeof(struct termios));
		if (error)
			return error;
		if (!arg) 
			return -EFAULT;
			
		memcpy_tofs((void *) arg, scc->tty->termios, sizeof(struct termios));
		return 0;
		
	case TCSETS:
	case TCSETSF:		/* should flush first, but... */
	case TCSETSW:		/* should wait 'till flush, but... */
		if (!suser())
			return -EPERM;
		if (!arg)
			return -EFAULT;
		
		memcpy_fromfs(scc->tty->termios, (void *) arg, sizeof(struct termios));
		scc_change_speed(scc);
		return 0;
		
		
	case TIOCSCCSTAT:
		error = verify_area(VERIFY_WRITE, (void *) arg,sizeof(struct scc_stat));
		if (error)
			return error;
		
		if (!arg)
			return -EFAULT;
			
		scc->stat.used_buf = scc_count_used_buffers(&scc->stat.rx_alloc, 
							    &scc->stat.tx_alloc);
			
		memcpy_tofs((void *) arg, &scc->stat, sizeof(struct scc_stat));
		return 0;
		
#define TICKS (100/TPS)
#define CAST(x) (unsigned long)(x)
#define  Val	kiss_cmd.param
#define  VAL	kiss_cmd.param*TPS/100
#define SVAL	kiss_cmd.param? kiss_cmd.param:TIMER_STOPPED

	case TIOCGKISS:
		error = verify_area(VERIFY_WRITE, (void *) arg,sizeof(struct ioctl_command));
		if (error)
			return error;
			
		if (!arg)
			return -EFAULT;
			
		memcpy_fromfs(&kiss_cmd, (void *) arg, sizeof(struct ioctl_command));

		switch (kiss_cmd.command)
		{
			case PARAM_TXDELAY:	r = CAST(scc->kiss.txdelay*TICKS);	break;
			case PARAM_PERSIST:	r = CAST(scc->kiss.persist); 		break;
			case PARAM_SLOTTIME:	r = CAST(scc->kiss.slottime*TICKS);	break;
			case PARAM_TXTAIL:	r = CAST(scc->kiss.tailtime*TICKS);	break;
			case PARAM_FULLDUP:	r = CAST(scc->kiss.fulldup); 		break;
			case PARAM_SOFTDCD:	r = CAST(scc->kiss.softdcd);		break;
			case PARAM_DTR:		r = CAST((scc->wreg[R5] & DTR)? 1:0); break;
			case PARAM_RTS:		r = CAST((scc->wreg[R5] & RTS)? 1:0); break;
			case PARAM_SPEED:	r = CAST(scc->modem.speed);	break;
			case PARAM_GROUP:	r = CAST(scc->kiss.group); 		break;
			case PARAM_IDLE:	r = CAST(scc->kiss.idletime);		break;
			case PARAM_MIN:		r = CAST(scc->kiss.mintime);		break;
			case PARAM_MAXKEY:	r = CAST(scc->kiss.maxkeyup);		break;
			case PARAM_WAIT:	r = CAST(scc->kiss.waittime);		break;
			case PARAM_MAXDEFER:	r = CAST(scc->kiss.maxdefer);		break;
			case PARAM_TX:		r = CAST(scc->kiss.tx_inhibit);	break;
			case PARAM_SLIP:	r = CAST(!scc->kiss.not_slip);		break;
			default:		r = NO_SUCH_PARAM;
		}
		
		kiss_cmd.param = r;
		
		memcpy_tofs((void *) arg, &kiss_cmd, sizeof(struct ioctl_command));
		return 0;
		break;
		
	case TIOCSKISS:
		if (!arg)
			return -EFAULT;

		if (!suser())
			return -EPERM;
			
		memcpy_fromfs(&kiss_cmd, (void *) arg, sizeof(struct ioctl_command));
		
		switch (kiss_cmd.command)
		{
			case PARAM_TXDELAY:	scc->kiss.txdelay=VAL;		break;
			case PARAM_PERSIST:	scc->kiss.persist=Val;		break;
			case PARAM_SLOTTIME:	scc->kiss.slottime=VAL;		break;
			case PARAM_TXTAIL:	scc->kiss.tailtime=VAL;		break;
			case PARAM_FULLDUP:	scc->kiss.fulldup=Val;		break;
			case PARAM_SOFTDCD:	scc->kiss.softdcd=Val;		break;
			case PARAM_DTR:		break; /* does someone need this? */
			case PARAM_RTS:		break; /* or this? */
			case PARAM_SPEED:	scc->modem.speed=Val;		break;
			case PARAM_GROUP:	scc->kiss.group=Val;		break;
			case PARAM_IDLE:	scc->kiss.idletime=Val;		break;
			case PARAM_MIN:		scc->kiss.mintime=SVAL;		break;
			case PARAM_MAXKEY:	scc->kiss.maxkeyup=SVAL;	break;
			case PARAM_WAIT:	scc->kiss.waittime=Val;		break;
			case PARAM_MAXDEFER:	scc->kiss.maxdefer=SVAL;	break;
			case PARAM_TX:		scc->kiss.tx_inhibit=Val;	break;
			case PARAM_SLIP:	scc->kiss.not_slip=!Val;	break;
			default:		return -ENOIOCTLCMD;
		}
		
		return 0;
		break;
#undef TICKS
#undef CAST
#undef VAL
#undef SVAL
#undef Val
		
	default:
		return -ENOIOCTLCMD;
    }
}


/* ----- TERMIOS function ----- */

static void
scc_set_termios(struct tty_struct * tty, struct termios * old_termios)
{
	if (tty->termios->c_cflag == old_termios->c_cflag) 
		return;
	scc_change_speed(tty->driver_data);
}


static inline void check_tx_queue(register struct scc_channel *scc)
{
	register struct mbuf *bp;
	
	if (scc->stat.tx_queued > QUEUE_THRES)
	{
		if (scc->sndq1 == NULLBUF)
		{
			printk("z8530drv: Warning - scc->stat.tx_queued shows overflow"
			       " (%d) but queue is empty\n", scc->stat.tx_queued);
			       
			scc->stat.tx_queued = 0;	/* correct it */
			scc->stat.nospace = 54321;	/* draw attention to it */
			return;
		}
			
		bp = scc->sndq1->anext;	/* don't use the one we currently use */
		
		while (bp && (scc->stat.tx_queued > QUEUE_HYST))
		{
			bp = scc_free_chain(bp, BT_TRANSMIT);
			scc->stat.tx_queued--;
			scc->stat.nospace++;
		}
		
		scc->sndq1->anext = bp;
	}
}



/* ----> tx routine: decode KISS data and scc_enqueue it <---- */

/* send raw frame to SCC. used for AX.25 */
int scc_write(struct tty_struct *tty, int from_user, unsigned char *buf, int count)
{
	struct scc_channel * scc = tty->driver_data;
	unsigned char tbuf[BUFSIZE], *p;
	int cnt, cnt2;
	
	if (!tty) return count;
	
	if (scc_paranoia_check(scc, tty->device, "scc_write"))
		return 0;

	if (scc->kiss.tx_inhibit) return count;
	
	check_tx_queue(scc);

	cnt2 = count;
	
	while (cnt2)
	{
		cnt   = cnt2 > BUFSIZE? BUFSIZE:cnt2;
		cnt2 -= cnt;
		
		if (from_user)
			memcpy_fromfs(tbuf, buf, cnt);
		else
			memcpy(tbuf, buf, cnt);
		
		buf += cnt;
			
		p=tbuf;
		
		while(cnt--) 
		  if (kiss_decode(scc, *p++))
		  {
		  	scc->stat.nospace++;
		  	return 0;
		  }
		  	
	} /* while cnt2 */
	
	return count;
}
				

/* put a single char into the buffer */

static void scc_put_char(struct tty_struct * tty, unsigned char ch)
{
	struct scc_channel *scc = tty->driver_data;
	unsigned char ch2;
	
	if (scc_paranoia_check(scc, tty->device, "scc_put_char"))
		return;
		
	ch2 = ch;
	scc_write(tty, 0, &ch2, 1);	/* that's all */
}

static void scc_flush_chars(struct tty_struct * tty)
{
	struct scc_channel *scc = tty->driver_data;
	
	scc_paranoia_check(scc, tty->device, "scc_flush_chars"); /* just to annoy the user... */
	
	return;	/* no flush needed */
}

/* the kernel does NOT use this routine yet... */

static int scc_write_room(struct tty_struct *tty)
{
	struct scc_channel *scc = tty->driver_data;
	
	if (scc_paranoia_check(scc, tty->device, "scc_write_room"))
		return 0;
	
	if (scc->stat.tx_alloc >= QUEUE_THRES)
	{
		printk("scc_write_room(): buffer full (ignore)\n");
		return 0;
	}
		
	return BUFSIZE;
}

static int scc_chars_in_buffer(struct tty_struct *tty)
{
	struct scc_channel *scc = tty->driver_data;
	
	if (scc && scc->sndq2)
		return scc->sndq2->cnt;
	else
		return 0;
}

static void scc_flush_buffer(struct tty_struct *tty)
{
	struct scc_channel *scc = tty->driver_data;
	
	if (scc_paranoia_check(scc, tty->device, "scc_flush_buffer"))
		return;
		
	scc->stat.tx_kiss_state = KISS_IDLE;
	
	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 scc_throttle(struct tty_struct *tty)
{
	struct scc_channel *scc = tty->driver_data;
	
	if (scc_paranoia_check(scc, tty->device, "scc_throttle"))
		return;
		
		
	/* dummy */
}

static void scc_unthrottle(struct tty_struct *tty)
{
	struct scc_channel *scc = tty->driver_data;
	
	if (scc_paranoia_check(scc, tty->device, "scc_unthrottle"))
		return;
		
	/* dummy */
}

static void scc_start(struct tty_struct *tty)
{
	struct scc_channel *scc = tty->driver_data;
	
	if (scc_paranoia_check(scc, tty->device, "scc_start"))
		return;
		
	/* dummy */
}
	                                            	

static void scc_stop(struct tty_struct *tty)
{
	struct scc_channel *scc = tty->driver_data;
	
	if (scc_paranoia_check(scc, tty->device, "scc_stop"))
		return;
		
	/* dummy */
}


/* ******************************************************************** */
/* * 			Init SCC driver 			      * */
/* ******************************************************************** */

long scc_init (long kmem_start)
{
	int chip, chan;
	register io_port ctrl;
	long flags;
	
	
        memset(&scc_driver, 0, sizeof(struct tty_driver));
        scc_driver.magic = TTY_DRIVER_MAGIC;
        scc_driver.name = "sc";
        scc_driver.major = TTY_MAJOR;		
        scc_driver.minor_start = 96;
        scc_driver.num = Nchips*2;
        scc_driver.type = TTY_DRIVER_TYPE_SERIAL;
        scc_driver.subtype = 0;			/* not needed */
        scc_driver.init_termios = tty_std_termios;
        scc_driver.init_termios.c_cflag = B9600	| CS8 | CREAD | HUPCL | CLOCAL;
        scc_driver.flags = TTY_DRIVER_REAL_RAW;
        scc_driver.refcount = &scc_refcount;	/* not needed yet */
        scc_driver.table = scc_table;
        scc_driver.termios = (struct termios **) scc_termios;
        scc_driver.termios_locked = (struct termios **) scc_termios_locked;
        scc_driver.open = scc_open;
        scc_driver.close = scc_close;
        scc_driver.write = scc_write;
        scc_driver.start = scc_start;
        scc_driver.stop = scc_stop;
        
        scc_driver.put_char = scc_put_char;
        scc_driver.flush_chars = scc_flush_chars;        
	scc_driver.write_room = scc_write_room;
	scc_driver.chars_in_buffer = scc_chars_in_buffer;
	scc_driver.flush_buffer = scc_flush_buffer;
	
	scc_driver.throttle = scc_throttle;
	scc_driver.unthrottle = scc_unthrottle;
        
        scc_driver.ioctl = scc_ioctl;
        scc_driver.set_termios = scc_set_termios;
        
        if (tty_register_driver(&scc_driver))
           panic("Couldn't register Z8530 SCC driver\n");
                                
	printk (BANNER);
	
	if (Nchips > MAXSCC) Nchips = MAXSCC;	/* to avoid the "DAU" (duemmster anzunehmender User) */

	/* reset and pre-init all chips in the system */
	
	for (chip = 0; chip < Nchips; chip++)
	{
		memset((char *) &SCC_Info[2*chip  ], 0, sizeof(struct scc_channel));
		memset((char *) &SCC_Info[2*chip+1], 0, sizeof(struct scc_channel));
		
		ctrl = SCC_ctrl[chip * 2];
		if (!ctrl) continue;

		save_flags(flags); cli();	/* because of 2-step accesses */
		

/* Hmm... this may fail on fast systems with cards who don't delay the INTACK */
/* If you are sure you specified the right port addresses and the driver doesn't */
/* recognize the chips, define DONT_CHECK in scc_config.h */

#ifndef DONT_CHECK
		check_region(ctrl, 1);

		Outb(ctrl, 0);
		OutReg(ctrl,R13,0x55);		/* is this chip realy there? */
		
		if (InReg(ctrl,R13) != 0x55 )
		{
			restore_flags(flags);
			continue;
		}
#endif
		
		SCC_Info[2*chip  ].magic    = SCC_MAGIC;
		SCC_Info[2*chip  ].ctrl     = SCC_ctrl[2*chip];
		SCC_Info[2*chip  ].data     = SCC_data[2*chip];
		SCC_Info[2*chip  ].enhanced = SCC_Enhanced[chip];
			
		SCC_Info[2*chip+1].magic    = SCC_MAGIC;
		SCC_Info[2*chip+1].ctrl     = SCC_ctrl[2*chip+1];
		SCC_Info[2*chip+1].data     = SCC_data[2*chip+1];
		SCC_Info[2*chip+1].enhanced = SCC_Enhanced[chip];

 
        	restore_flags(flags);
        }
        
#ifdef VERBOSE_BOOTMSG
	printk("Init Z8530 driver: %u channels, using irq %u\n",Nchips*2,Ivec);
	

	for (chan = 0; chan < Nchips * 2 ; chan++)
	{
		printk("/dev/%s%i: data port = 0x%3.3x  control port = 0x%3.3x -- %s\n",
			scc_driver.name, chan, SCC_data[chan], SCC_ctrl[chan],
			SCC_Info[chan].ctrl? "found"   : "missing");
			
		if (SCC_Info[chan].ctrl == 0) 
		{
			SCC_ctrl[chan] = 0;
		} else {
			request_region(SCC_ctrl[chan], 1, "scc ctrl");
			request_region(SCC_data[chan], 1, "scc data");
		}
	}
#else
	printk("Init Z8530 driver: %u channels\n",Nchips*2);
#endif

	
	return kmem_start;
}
#endif
