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

/*
 *	baycom.c  -- baycom ser12 and par96 radio modem driver.
 *
 *	Copyright (C) 1996  Thomas Sailer (sailer@ife.ee.ethz.ch)
 *
 *	This program is free software; you can redistribute it and/or modify
 *	it under the terms of the GNU General Public License as published by
 *	the Free Software Foundation; either version 2 of the License, or
 *	(at your option) any later version.
 *
 *	This program is distributed in the hope that it will be useful,
 *	but WITHOUT ANY WARRANTY; without even the implied warranty of
 *	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *	GNU General Public License for more details.
 *
 *	You should have received a copy of the GNU General Public License
 *	along with this program; if not, write to the Free Software
 *	Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
 *
 *  Please note that the GPL allows you to use the driver, NOT the radio.
 *  In order to use the radio, you need a license from the communications
 *  authority of your country.
 *
 *
 *  Supported modems
 *
 *  ser12:  This is a very simple 1200 baud AFSK modem. The modem consists only
 *          of a modulator/demodulator chip, usually a TI TCM3105. The computer
 *          is responsible for regenerating the receiver bit clock, as well as
 *          for handling the HDLC protocol. The modem connects to a serial port,
 *          hence the name. Since the serial port is not used as an async serial
 *          port, the kernel driver for serial ports cannot be used, and this
 *          driver only supports standard serial hardware (8250, 16450, 16550)
 *
 *  par96:  This is a modem for 9600 baud FSK compatible to the G3RUH standard.
 *          The modem does all the filtering and regenerates the receiver clock.
 *          Data is transferred from and to the PC via a shift register.
 *          The shift register is filled with 16 bits and an interrupt is
 *          signalled. The PC then empties the shift register in a burst. This
 *          modem connects to the parallel port, hence the name. The modem
 *          leaves the implementation of the HDLC protocol and the scrambler
 *          polynomial to the PC. This modem is no longer available (at least
 *          from Baycom) and has been replaced by the PICPAR modem (see below).
 *          You may however still build one from the schematics published in
 *          cq-DL :-).
 *
 *  picpar: This is a redesign of the par96 modem by Henning Rech, DF9IC. The
 *          modem is protocol compatible to par96, but uses only three low
 *          power ICs and can therefore be fed from the parallel port and
 *          does not require an additional power supply. It features
 *          built in DCD circuitry. The driver should therefore be configured
 *          for hardware DCD.
 *
 *
 *  Command line options (insmod command line)
 *
 *  mode     driver mode string. Valid choices are ser12 and par96. An
 *           optional * enables software DCD.
 *           2=par96/par97, any other value invalid
 *  iobase   base address of the port; common values are for ser12 0x3f8,
 *           0x2f8, 0x3e8, 0x2e8 and for par96/par97 0x378, 0x278, 0x3bc
 *  irq      interrupt line of the port; common values are for ser12 3,4
 *           and for par96/par97 7
 *
 *
 *  History:
 *   0.1  26.06.96  Adapted from baycom.c and made network driver interface
 *        18.10.96  Changed to new user space access routines (copy_{to,from}_user)
 *   0.3  26.04.97  init code/data tagged
 *   0.4  08.07.97  alternative ser12 decoding algorithm (uses delta CTS ints)
 */

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

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/sched.h>
#include <linux/types.h>
#include <linux/fcntl.h>
#include <linux/interrupt.h>
#include <linux/ioport.h>
#include <linux/in.h>
#include <linux/string.h>
#include <asm/system.h>
#include <asm/bitops.h>
#include <asm/io.h>
#include <linux/delay.h>
#include <linux/errno.h>
#include <linux/netdevice.h>
#include <linux/hdlcdrv.h>
#include <linux/baycom.h>

/* --------------------------------------------------------------------- */

/*
 * currently this module is supposed to support both module styles, i.e.
 * the old one present up to about 2.1.9, and the new one functioning
 * starting with 2.1.21. The reason is I have a kit allowing to compile
 * this module also under 2.0.x which was requested by several people.
 * This will go in 2.2
 */
#include <linux/version.h>

#if LINUX_VERSION_CODE >= 0x20100
#include <asm/uaccess.h>
#else
#include <asm/segment.h>
#include <linux/mm.h>

#undef put_user
#undef get_user

#define put_user(x,ptr) ({ __put_user((unsigned long)(x),(ptr),sizeof(*(ptr))); 0; })
#define get_user(x,ptr) ({ x = ((__typeof__(*(ptr)))__get_user((ptr),sizeof(*(ptr)))); 0; })

extern inline int copy_from_user(void *to, const void *from, unsigned long n)
{
        int i = verify_area(VERIFY_READ, from, n);
        if (i)
                return i;
        memcpy_fromfs(to, from, n);
        return 0;
}

extern inline int copy_to_user(void *to, const void *from, unsigned long n)
{
        int i = verify_area(VERIFY_WRITE, to, n);
        if (i)
                return i;
        memcpy_tofs(to, from, n);
        return 0;
}
#endif

#if LINUX_VERSION_CODE >= 0x20123
#include <linux/init.h>
#else
#define __init
#define __initdata
#define __initfunc(x) x
#endif

/* --------------------------------------------------------------------- */

#define BAYCOM_DEBUG

/*
 * modem options; bit mask
 */
#define BAYCOM_OPTIONS_SOFTDCD  1
#define BAYCOM_ALT_SER12

/* --------------------------------------------------------------------- */

static const char bc_drvname[] = "baycom";
static const char bc_drvinfo[] = KERN_INFO "baycom: (C) 1996 Thomas Sailer, HB9JNX/AE4WA\n"
KERN_INFO "baycom: version 0.4 compiled " __TIME__ " " __DATE__ "\n";

/* --------------------------------------------------------------------- */

#define NR_PORTS 4

static struct device baycom_device[NR_PORTS];

static struct {
	char *mode;
	int iobase, irq;
} baycom_ports[NR_PORTS] = { { NULL, 0, 0 }, };

/* --------------------------------------------------------------------- */

#define RBR(iobase) (iobase+0)
#define THR(iobase) (iobase+0)
#define IER(iobase) (iobase+1)
#define IIR(iobase) (iobase+2)
#define FCR(iobase) (iobase+2)
#define LCR(iobase) (iobase+3)
#define MCR(iobase) (iobase+4)
#define LSR(iobase) (iobase+5)
#define MSR(iobase) (iobase+6)
#define SCR(iobase) (iobase+7)
#define DLL(iobase) (iobase+0)
#define DLM(iobase) (iobase+1)

#define SER12_EXTENT 8

#define LPT_DATA(iobase)    (iobase+0)
#define LPT_STATUS(iobase)  (iobase+1)
#define LPT_CONTROL(iobase) (iobase+2)
#define LPT_IRQ_ENABLE      0x10
#define PAR96_BURSTBITS 16
#define PAR96_BURST     4
#define PAR96_PTT       2
#define PAR96_TXBIT     1
#define PAR96_ACK       0x40
#define PAR96_RXBIT     0x20
#define PAR96_DCD       0x10
#define PAR97_POWER     0xf8

#define PAR96_EXTENT 3

/* ---------------------------------------------------------------------- */
/*
 * Information that need to be kept for each board.
 */

struct baycom_state {
	struct hdlcdrv_state hdrv;

	unsigned int options;

	struct modem_state {
		short arb_divider;
		unsigned char flags;
		unsigned int shreg;
		struct modem_state_ser12 {
			unsigned char tx_bit;
			int dcd_sum0, dcd_sum1, dcd_sum2;
			unsigned char last_sample;
			unsigned char last_rxbit;
			unsigned int dcd_shreg;
			unsigned int dcd_time;
			unsigned int bit_pll;
#ifdef BAYCOM_ALT_SER12
			unsigned long last_jiffies;
			unsigned int pll_time;
			unsigned int txshreg;
#else /* BAYCOM_ALT_SER12 */
			unsigned char interm_sample;
#endif /* BAYCOM_ALT_SER12 */
		} ser12;
		struct modem_state_par96 {
			int dcd_count;
			unsigned int dcd_shreg;
			unsigned long descram;
			unsigned long scram;
		} par96;
	} modem;

#ifdef BAYCOM_DEBUG
	struct debug_vals {
		unsigned long last_jiffies;
		unsigned cur_intcnt;
		unsigned last_intcnt;
		int cur_pllcorr;
		int last_pllcorr;
	} debug_vals;
#endif /* BAYCOM_DEBUG */
};

/* --------------------------------------------------------------------- */

#define min(a, b) (((a) < (b)) ? (a) : (b))
#define max(a, b) (((a) > (b)) ? (a) : (b))

/* --------------------------------------------------------------------- */

static void inline baycom_int_freq(struct baycom_state *bc)
{
#ifdef BAYCOM_DEBUG
	unsigned long cur_jiffies = jiffies;
	/*
	 * measure the interrupt frequency
	 */
	bc->debug_vals.cur_intcnt++;
	if ((cur_jiffies - bc->debug_vals.last_jiffies) >= HZ) {
		bc->debug_vals.last_jiffies = cur_jiffies;
		bc->debug_vals.last_intcnt = bc->debug_vals.cur_intcnt;
		bc->debug_vals.cur_intcnt = 0;
		bc->debug_vals.last_pllcorr = bc->debug_vals.cur_pllcorr;
		bc->debug_vals.cur_pllcorr = 0;
	}
#endif /* BAYCOM_DEBUG */
}

/* --------------------------------------------------------------------- */
/*
 * ===================== SER12 specific routines =========================
 */

#ifdef BAYCOM_ALT_SER12

#define SER12_BAUD 1200

/* --------------------------------------------------------------------- */

extern inline unsigned int hweight16(unsigned short w)
        __attribute__ ((unused));
extern inline unsigned int hweight8(unsigned char w)
        __attribute__ ((unused));

extern inline unsigned int hweight16(unsigned short w)
{
        unsigned short res = (w & 0x5555) + ((w >> 1) & 0x5555);
        res = (res & 0x3333) + ((res >> 2) & 0x3333);
        res = (res & 0x0F0F) + ((res >> 4) & 0x0F0F);
        return (res & 0x00FF) + ((res >> 8) & 0x00FF);
}

extern inline unsigned int hweight8(unsigned char w)
{
        unsigned short res = (w & 0x55) + ((w >> 1) & 0x55);
        res = (res & 0x33) + ((res >> 2) & 0x33);
        return (res & 0x0F) + ((res >> 4) & 0x0F);
}

/* --------------------------------------------------------------------- */

static __inline__ void ser12_rxsample(struct device *dev, struct baycom_state *bc, unsigned char news)
{
	bc->modem.ser12.dcd_shreg <<= 1;
	bc->modem.ser12.bit_pll += 0x2000;
	if (bc->modem.ser12.last_sample != news) {
		bc->modem.ser12.last_sample = news;
		bc->modem.ser12.dcd_shreg |= 1;
		if (bc->modem.ser12.bit_pll < 0x9000)
			bc->modem.ser12.bit_pll += 0x1000;
		else
			bc->modem.ser12.bit_pll -= 0x1000;
		bc->modem.ser12.dcd_sum0 += 4 * hweight8(bc->modem.ser12.dcd_shreg & 0x38)
			- hweight16(bc->modem.ser12.dcd_shreg & 0x7c0);
	}
	hdlcdrv_channelbit(&bc->hdrv, !!bc->modem.ser12.last_sample);
	if ((--bc->modem.ser12.dcd_time) <= 0) {
		hdlcdrv_setdcd(&bc->hdrv, (bc->modem.ser12.dcd_sum0 + 
					   bc->modem.ser12.dcd_sum1 + 
					   bc->modem.ser12.dcd_sum2) < 0);
		bc->modem.ser12.dcd_sum2 = bc->modem.ser12.dcd_sum1;
		bc->modem.ser12.dcd_sum1 = bc->modem.ser12.dcd_sum0;
		bc->modem.ser12.dcd_sum0 = 2; /* slight bias */
		bc->modem.ser12.dcd_time = 120;
	}
	if (bc->modem.ser12.bit_pll >= 0x10000) {
		bc->modem.ser12.bit_pll &= 0xffff;
		bc->modem.shreg >>= 1;
		if (bc->modem.ser12.last_rxbit == bc->modem.ser12.last_sample)
			bc->modem.shreg |=  0x10000;
		bc->modem.ser12.last_rxbit = bc->modem.ser12.last_sample;
		if (bc->modem.shreg & 1) {
			hdlcdrv_putbits(&bc->hdrv, bc->modem.shreg >> 1);
			bc->modem.shreg = 0x10000;
		}
	}
}

/* --------------------------------------------------------------------- */

static __inline__ void ser12_rx(struct device *dev, struct baycom_state *bc, unsigned char curs)
{
	unsigned long curjiff;
	struct timeval tv;
	unsigned int timediff;

	/*
	 * get current time
	 */
	curjiff = jiffies;
	do_gettimeofday(&tv);
	if ((signed)(curjiff - bc->modem.ser12.last_jiffies) >= HZ/4) {
		/* long inactivity; clear HDLC and DCD */
		bc->modem.ser12.dcd_sum1 = 0;
		bc->modem.ser12.dcd_sum2 = 0;
		bc->modem.ser12.dcd_sum0 = 2;
		bc->modem.ser12.dcd_time = 120;
		hdlcdrv_setdcd(&bc->hdrv, 0);
		hdlcdrv_putbits(&bc->hdrv, 0xffff);
		bc->modem.ser12.last_jiffies = curjiff;
		bc->modem.ser12.pll_time = tv.tv_usec;
	}
	bc->modem.ser12.last_jiffies = curjiff;
	timediff = tv.tv_usec + 1000000 - bc->modem.ser12.pll_time;
	timediff %= 1000000;
	timediff /= 125000/SER12_BAUD;
	bc->modem.ser12.pll_time = (bc->modem.ser12.pll_time + timediff * (125000/SER12_BAUD)) % 1000000;
	for (; timediff > 1; timediff--)
		ser12_rxsample(dev, bc, bc->modem.ser12.last_sample);
	if (timediff >= 1)
		ser12_rxsample(dev, bc, curs);
}

/* --------------------------------------------------------------------- */

static void ser12_interrupt(int irq, void *dev_id, struct pt_regs *regs)
{
	struct device *dev = (struct device *)dev_id;
	struct baycom_state *bc = (struct baycom_state *)dev->priv;
	unsigned char iir, msr = 0;
	unsigned int txcount = 0;
	unsigned int rxcount = 0;

	if (!dev || !bc || bc->hdrv.magic != HDLCDRV_MAGIC)
		return;
	
	for (;;) {
		iir = inb(IIR(dev->base_addr));
		if (iir & 1)
			break;
		switch (iir & 6) {
		case 6:
			inb(LSR(dev->base_addr));
			continue;
			
		case 4:
			inb(RBR(dev->base_addr));
			continue;
			
		case 2:
			/*
			 * make sure the next interrupt is generated;
			 * 0 must be used to power the modem; the modem draws its
			 * power from the TxD line
			 */
			outb(0x00, THR(dev->base_addr));
			bc->modem.arb_divider--;
			baycom_int_freq(bc);
			if (hdlcdrv_ptt(&bc->hdrv)) {
				/*
				 * first output the last bit (!) then call HDLC transmitter,
				 * since this may take quite long
				 */
				outb(0x0e | (!!bc->modem.ser12.tx_bit), MCR(dev->base_addr));
				txcount++;
			} else
				outb(0x0d, MCR(dev->base_addr));       /* transmitter off */
			continue;
			
		default:
			msr = inb(MSR(dev->base_addr));
			if (msr & 1)  /* delta CTS interrupt */
				rxcount++;
			continue;
		}
	}
	if (rxcount)
		ser12_rx(dev, bc, msr & 0x10);
	if (txcount) {
#ifdef BAYCOM_DEBUG
		if (bc->debug_vals.cur_pllcorr < txcount)
			bc->debug_vals.cur_pllcorr = txcount;
#endif /* BAYCOM_DEBUG */
		if (bc->modem.ser12.txshreg <= 1)
			bc->modem.ser12.txshreg = 0x10000 | hdlcdrv_getbits(&bc->hdrv);
		bc->modem.ser12.tx_bit = !(bc->modem.ser12.tx_bit ^ (bc->modem.ser12.txshreg & 1));
		bc->modem.ser12.txshreg >>= 1;
	}
	sti();
	if (bc->modem.arb_divider <= 0) {
		bc->modem.arb_divider = SER12_BAUD/100;
		hdlcdrv_arbitrate(dev, &bc->hdrv);
	}
	hdlcdrv_transmitter(dev, &bc->hdrv);
	hdlcdrv_receiver(dev, &bc->hdrv);
}

/* --------------------------------------------------------------------- */
#else /* BAYCOM_ALT_SER12 */

static void inline ser12_set_divisor(struct device *dev,
				     unsigned char divisor)
{
	outb(0x81, LCR(dev->base_addr));	/* DLAB = 1 */
	outb(divisor, DLL(dev->base_addr));
	outb(0, DLM(dev->base_addr));
	outb(0x01, LCR(dev->base_addr));	/* word length = 6 */
	/*
	 * make sure the next interrupt is generated;
	 * 0 must be used to power the modem; the modem draws its
	 * power from the TxD line
	 */
	outb(0x00, THR(dev->base_addr));
	/*
	 * it is important not to set the divider while transmitting;
	 * this reportedly makes some UARTs generating interrupts
	 * in the hundredthousands per second region
	 * Reported by: Ignacio.Arenaza@studi.epfl.ch (Ignacio Arenaza Nuno)
	 */
}

/* --------------------------------------------------------------------- */

/*
 * must call the TX arbitrator every 10ms
 */
#define SER12_ARB_DIVIDER(bc) ((bc->options & BAYCOM_OPTIONS_SOFTDCD) ? \
			       36 : 24)
#define SER12_DCD_INTERVAL(bc) ((bc->options & BAYCOM_OPTIONS_SOFTDCD) ? \
				240 : 12)

static inline void ser12_tx(struct device *dev, struct baycom_state *bc)
{
	/* one interrupt per channel bit */
	ser12_set_divisor(dev, 12);
	/*
	 * first output the last bit (!) then call HDLC transmitter,
	 * since this may take quite long
	 */
	outb(0x0e | (!!bc->modem.ser12.tx_bit), MCR(dev->base_addr));
	if (bc->modem.shreg <= 1)
		bc->modem.shreg = 0x10000 | hdlcdrv_getbits(&bc->hdrv);
	bc->modem.ser12.tx_bit = !(bc->modem.ser12.tx_bit ^
				   (bc->modem.shreg & 1));
	bc->modem.shreg >>= 1;
}

/* --------------------------------------------------------------------- */

static inline void ser12_rx(struct device *dev, struct baycom_state *bc)
{
	unsigned char cur_s;
	/*
	 * do demodulator
	 */
	cur_s = inb(MSR(dev->base_addr)) & 0x10;	/* the CTS line */
	hdlcdrv_channelbit(&bc->hdrv, cur_s);
	bc->modem.ser12.dcd_shreg = (bc->modem.ser12.dcd_shreg << 1) |
		(cur_s != bc->modem.ser12.last_sample);
	bc->modem.ser12.last_sample = cur_s;
	if(bc->modem.ser12.dcd_shreg & 1) {
		if (bc->options & BAYCOM_OPTIONS_SOFTDCD) {
			unsigned int dcdspos, dcdsneg;

			dcdspos = dcdsneg = 0;
			dcdspos += ((bc->modem.ser12.dcd_shreg >> 1) & 1);
			if (!(bc->modem.ser12.dcd_shreg & 0x7ffffffe))
				dcdspos += 2;
			dcdsneg += ((bc->modem.ser12.dcd_shreg >> 2) & 1);
			dcdsneg += ((bc->modem.ser12.dcd_shreg >> 3) & 1);
			dcdsneg += ((bc->modem.ser12.dcd_shreg >> 4) & 1);

			bc->modem.ser12.dcd_sum0 += 16*dcdspos - dcdsneg;
		} else
			bc->modem.ser12.dcd_sum0--;
	}
	if(!bc->modem.ser12.dcd_time) {
		hdlcdrv_setdcd(&bc->hdrv, (bc->modem.ser12.dcd_sum0 +
					   bc->modem.ser12.dcd_sum1 +
					   bc->modem.ser12.dcd_sum2) < 0);
		bc->modem.ser12.dcd_sum2 = bc->modem.ser12.dcd_sum1;
		bc->modem.ser12.dcd_sum1 = bc->modem.ser12.dcd_sum0;
		/* offset to ensure DCD off on silent input */
		bc->modem.ser12.dcd_sum0 = 2;
		bc->modem.ser12.dcd_time = SER12_DCD_INTERVAL(bc);
	}
	bc->modem.ser12.dcd_time--;
	if (bc->options & BAYCOM_OPTIONS_SOFTDCD) {
		/*
		 * PLL code for the improved software DCD algorithm
		 */
		if (bc->modem.ser12.interm_sample) {
			/*
			 * intermediate sample; set timing correction to normal
			 */
			ser12_set_divisor(dev, 4);
		} else {
			/*
			 * do PLL correction and call HDLC receiver
			 */
			switch (bc->modem.ser12.dcd_shreg & 7) {
			case 1: /* transition too late */
				ser12_set_divisor(dev, 5);
#ifdef BAYCOM_DEBUG
				bc->debug_vals.cur_pllcorr++;
#endif /* BAYCOM_DEBUG */
				break;
			case 4:	/* transition too early */
				ser12_set_divisor(dev, 3);
#ifdef BAYCOM_DEBUG
				bc->debug_vals.cur_pllcorr--;
#endif /* BAYCOM_DEBUG */
				break;
			default:
				ser12_set_divisor(dev, 4);
				break;
			}
			bc->modem.shreg >>= 1;
			if (bc->modem.ser12.last_sample ==
			    bc->modem.ser12.last_rxbit)
				bc->modem.shreg |= 0x10000;
			bc->modem.ser12.last_rxbit =
				bc->modem.ser12.last_sample;
		}
		if (++bc->modem.ser12.interm_sample >= 3)
			bc->modem.ser12.interm_sample = 0;
		/*
		 * DCD stuff
		 */
		if (bc->modem.ser12.dcd_shreg & 1) {
			unsigned int dcdspos, dcdsneg;

			dcdspos = dcdsneg = 0;
			dcdspos += ((bc->modem.ser12.dcd_shreg >> 1) & 1);
			dcdspos += (!(bc->modem.ser12.dcd_shreg & 0x7ffffffe))
				<< 1;
			dcdsneg += ((bc->modem.ser12.dcd_shreg >> 2) & 1);
			dcdsneg += ((bc->modem.ser12.dcd_shreg >> 3) & 1);
			dcdsneg += ((bc->modem.ser12.dcd_shreg >> 4) & 1);

			bc->modem.ser12.dcd_sum0 += 16*dcdspos - dcdsneg;
		}
	} else {
		/*
		 * PLL algorithm for the hardware squelch DCD algorithm
		 */
		if (bc->modem.ser12.interm_sample) {
			/*
			 * intermediate sample; set timing correction to normal
			 */
			ser12_set_divisor(dev, 6);
		} else {
			/*
			 * do PLL correction and call HDLC receiver
			 */
			switch (bc->modem.ser12.dcd_shreg & 3) {
			case 1: /* transition too late */
				ser12_set_divisor(dev, 7);
#ifdef BAYCOM_DEBUG
				bc->debug_vals.cur_pllcorr++;
#endif /* BAYCOM_DEBUG */
				break;
			case 2:	/* transition too early */
				ser12_set_divisor(dev, 5);
#ifdef BAYCOM_DEBUG
				bc->debug_vals.cur_pllcorr--;
#endif /* BAYCOM_DEBUG */
				break;
			default:
				ser12_set_divisor(dev, 6);
				break;
			}
			bc->modem.shreg >>= 1;
			if (bc->modem.ser12.last_sample ==
			    bc->modem.ser12.last_rxbit)
				bc->modem.shreg |= 0x10000;
			bc->modem.ser12.last_rxbit =
				bc->modem.ser12.last_sample;
		}
		bc->modem.ser12.interm_sample = !bc->modem.ser12.interm_sample;
		/*
		 * DCD stuff
		 */
		bc->modem.ser12.dcd_sum0 -= (bc->modem.ser12.dcd_shreg & 1);
	}
	outb(0x0d, MCR(dev->base_addr));		/* transmitter off */
	if (bc->modem.shreg & 1) {
		hdlcdrv_putbits(&bc->hdrv, bc->modem.shreg >> 1);
		bc->modem.shreg = 0x10000;
	}
	if(!bc->modem.ser12.dcd_time) {
		hdlcdrv_setdcd(&bc->hdrv, (bc->modem.ser12.dcd_sum0 +
					   bc->modem.ser12.dcd_sum1 +
					   bc->modem.ser12.dcd_sum2) < 0);
		bc->modem.ser12.dcd_sum2 = bc->modem.ser12.dcd_sum1;
		bc->modem.ser12.dcd_sum1 = bc->modem.ser12.dcd_sum0;
		/* offset to ensure DCD off on silent input */
		bc->modem.ser12.dcd_sum0 = 2;
		bc->modem.ser12.dcd_time = SER12_DCD_INTERVAL(bc);
	}
	bc->modem.ser12.dcd_time--;
}

/* --------------------------------------------------------------------- */

static void ser12_interrupt(int irq, void *dev_id, struct pt_regs *regs)
{
	struct device *dev = (struct device *)dev_id;
	struct baycom_state *bc = (struct baycom_state *)dev->priv;

	if (!dev || !bc || bc->hdrv.magic != HDLCDRV_MAGIC)
		return;

	baycom_int_freq(bc);
	/*
	 * check if transmitter active
	 */
	if (hdlcdrv_ptt(&bc->hdrv))
		ser12_tx(dev, bc);
	else {
		ser12_rx(dev, bc);
		if (--bc->modem.arb_divider <= 0) {
			bc->modem.arb_divider = SER12_ARB_DIVIDER(bc);
			sti();
			hdlcdrv_arbitrate(dev, &bc->hdrv);
		}
	}
	sti();
	hdlcdrv_transmitter(dev, &bc->hdrv);
	hdlcdrv_receiver(dev, &bc->hdrv);
}
#endif /* BAYCOM_ALT_SER12 */

/* --------------------------------------------------------------------- */

enum uart { c_uart_unknown, c_uart_8250,
	    c_uart_16450, c_uart_16550, c_uart_16550A};
static const char *uart_str[] = { 
	"unknown", "8250", "16450", "16550", "16550A" 
};

static enum uart ser12_check_uart(unsigned int iobase)
{
	unsigned char b1,b2,b3;
	enum uart u;
	enum uart uart_tab[] =
		{ c_uart_16450, c_uart_unknown, c_uart_16550, c_uart_16550A };

	b1 = inb(MCR(iobase));
	outb(b1 | 0x10, MCR(iobase));	/* loopback mode */
	b2 = inb(MSR(iobase));
	outb(0x1a, MCR(iobase));
	b3 = inb(MSR(iobase)) & 0xf0;
	outb(b1, MCR(iobase));			/* restore old values */
	outb(b2, MSR(iobase));
	if (b3 != 0x90)
		return c_uart_unknown;
	inb(RBR(iobase));
	inb(RBR(iobase));
	outb(0x01, FCR(iobase));		/* enable FIFOs */
	u = uart_tab[(inb(IIR(iobase)) >> 6) & 3];
	if (u == c_uart_16450) {
		outb(0x5a, SCR(iobase));
		b1 = inb(SCR(iobase));
		outb(0xa5, SCR(iobase));
		b2 = inb(SCR(iobase));
		if ((b1 != 0x5a) || (b2 != 0xa5))
			u = c_uart_8250;
	}
	return u;
}

/* --------------------------------------------------------------------- */

static int ser12_open(struct device *dev)
{
	struct baycom_state *bc = (struct baycom_state *)dev->priv;
	enum uart u;

	if (!dev || !bc)
		return -ENXIO;
	if (!dev->base_addr || dev->base_addr > 0x1000-SER12_EXTENT ||
	    dev->irq < 2 || dev->irq > 15)
		return -ENXIO;
	if (check_region(dev->base_addr, SER12_EXTENT))
		return -EACCES;
	memset(&bc->modem, 0, sizeof(bc->modem));
	bc->hdrv.par.bitrate = 1200;
	if ((u = ser12_check_uart(dev->base_addr)) == c_uart_unknown)
		return -EIO;
	outb(0, FCR(dev->base_addr));  /* disable FIFOs */
	outb(0x0d, MCR(dev->base_addr));
	outb(0x0d, MCR(dev->base_addr));
	outb(0, IER(dev->base_addr));
	if (request_irq(dev->irq, ser12_interrupt, SA_INTERRUPT,
			"baycom_ser12", dev))
		return -EBUSY;
	request_region(dev->base_addr, SER12_EXTENT, "baycom_ser12");
#ifdef BAYCOM_ALT_SER12
	bc->hdrv.par.bitrate = SER12_BAUD;
	/*
	 * set the SIO to 6 Bits/character and 19600 baud, so that
	 * we get exactly (hopefully) one interrupt per radio symbol
	 */
	outb(0x81, LCR(dev->base_addr));	/* DLAB = 1 */
	outb(115200/8/SER12_BAUD, DLL(dev->base_addr));
	outb(0, DLM(dev->base_addr));
	outb(0x01, LCR(dev->base_addr));	/* word length = 6 */
	/*
	 * enable transmitter empty interrupt and modem status interrupt
	 */
	outb(0x0a, IER(dev->base_addr));
	/*
	 * make sure the next interrupt is generated;
	 * 0 must be used to power the modem; the modem draws its
	 * power from the TxD line
	 */
	outb(0x00, THR(dev->base_addr));
	printk(KERN_INFO "%s: ser12(alt modem) at iobase 0x%lx irq %u options "
	       "0x%x uart %s\n", bc_drvname, dev->base_addr, dev->irq,
	       bc->options, uart_str[u]);
#else /* BAYCOM_ALT_SER12 */
	/*
	 * enable transmitter empty interrupt
	 */
	outb(2, IER(dev->base_addr));
	/*
	 * set the SIO to 6 Bits/character and 19200 or 28800 baud, so that
	 * we get exactly (hopefully) 2 or 3 interrupts per radio symbol,
	 * depending on the usage of the software DCD routine
	 */
	ser12_set_divisor(dev, (bc->options & BAYCOM_OPTIONS_SOFTDCD) ? 4 : 6);
	printk(KERN_INFO "%s: ser12 at iobase 0x%lx irq %u options "
	       "0x%x uart %s\n", bc_drvname, dev->base_addr, dev->irq,
	       bc->options, uart_str[u]);
#endif /* BAYCOM_ALT_SER12 */
	MOD_INC_USE_COUNT;
	return 0;
}

/* --------------------------------------------------------------------- */

static int ser12_close(struct device *dev)
{
	struct baycom_state *bc = (struct baycom_state *)dev->priv;

	if (!dev || !bc)
		return -EINVAL;
	/*
	 * disable interrupts
	 */
	outb(0, IER(dev->base_addr));
	outb(1, MCR(dev->base_addr));
	free_irq(dev->irq, dev);
	release_region(dev->base_addr, SER12_EXTENT);
	printk(KERN_INFO "%s: close ser12 at iobase 0x%lx irq %u\n",
	       bc_drvname, dev->base_addr, dev->irq);
	MOD_DEC_USE_COUNT;
	return 0;
}

/* --------------------------------------------------------------------- */
/*
 * ===================== PAR96 specific routines =========================
 */

#define PAR96_DESCRAM_TAP1 0x20000
#define PAR96_DESCRAM_TAP2 0x01000
#define PAR96_DESCRAM_TAP3 0x00001

#define PAR96_DESCRAM_TAPSH1 17
#define PAR96_DESCRAM_TAPSH2 12
#define PAR96_DESCRAM_TAPSH3 0

#define PAR96_SCRAM_TAP1 0x20000 /* X^17 */
#define PAR96_SCRAM_TAPN 0x00021 /* X^0+X^5 */

/* --------------------------------------------------------------------- */

static inline void par96_tx(struct device *dev, struct baycom_state *bc)
{
	int i;
	unsigned int data = hdlcdrv_getbits(&bc->hdrv);

	for(i = 0; i < PAR96_BURSTBITS; i++, data >>= 1) {
		unsigned char val = PAR97_POWER;
		bc->modem.par96.scram = ((bc->modem.par96.scram << 1) |
					 (bc->modem.par96.scram & 1));
		if (!(data & 1))
			bc->modem.par96.scram ^= 1;
		if (bc->modem.par96.scram & (PAR96_SCRAM_TAP1 << 1))
			bc->modem.par96.scram ^=
				(PAR96_SCRAM_TAPN << 1);
		if (bc->modem.par96.scram & (PAR96_SCRAM_TAP1 << 2))
			val |= PAR96_TXBIT;
		outb(val, LPT_DATA(dev->base_addr));
		outb(val | PAR96_BURST, LPT_DATA(dev->base_addr));
	}
}

/* --------------------------------------------------------------------- */

static inline void par96_rx(struct device *dev, struct baycom_state *bc)
{
	int i;
	unsigned int data, mask, mask2, descx;

	/*
	 * do receiver; differential decode and descramble on the fly
	 */
	for(data = i = 0; i < PAR96_BURSTBITS; i++) {
		bc->modem.par96.descram = (bc->modem.par96.descram << 1);
		if (inb(LPT_STATUS(dev->base_addr)) & PAR96_RXBIT)
			bc->modem.par96.descram |= 1;
		descx = bc->modem.par96.descram ^
			(bc->modem.par96.descram >> 1);
		/* now the diff decoded data is inverted in descram */
		outb(PAR97_POWER | PAR96_PTT, LPT_DATA(dev->base_addr));
		descx ^= ((descx >> PAR96_DESCRAM_TAPSH1) ^
			  (descx >> PAR96_DESCRAM_TAPSH2));
		data >>= 1;
		if (!(descx & 1))
			data |= 0x8000;
		outb(PAR97_POWER | PAR96_PTT | PAR96_BURST,
		     LPT_DATA(dev->base_addr));
	}
	hdlcdrv_putbits(&bc->hdrv, data);
	/*
	 * do DCD algorithm
	 */
	if (bc->options & BAYCOM_OPTIONS_SOFTDCD) {
		bc->modem.par96.dcd_shreg = (bc->modem.par96.dcd_shreg >> 16)
			| (data << 16);
		/* search for flags and set the dcd counter appropriately */
		for(mask = 0x1fe00, mask2 = 0xfc00, i = 0;
		    i < PAR96_BURSTBITS; i++, mask <<= 1, mask2 <<= 1)
			if ((bc->modem.par96.dcd_shreg & mask) == mask2)
				bc->modem.par96.dcd_count = HDLCDRV_MAXFLEN+4;
		/* check for abort/noise sequences */
		for(mask = 0x1fe00, mask2 = 0x1fe00, i = 0;
		    i < PAR96_BURSTBITS; i++, mask <<= 1, mask2 <<= 1)
			if (((bc->modem.par96.dcd_shreg & mask) == mask2) &&
			    (bc->modem.par96.dcd_count >= 0))
				bc->modem.par96.dcd_count -= HDLCDRV_MAXFLEN-10;
		/* decrement and set the dcd variable */
		if (bc->modem.par96.dcd_count >= 0)
			bc->modem.par96.dcd_count -= 2;
		hdlcdrv_setdcd(&bc->hdrv, bc->modem.par96.dcd_count > 0);
	} else {
		hdlcdrv_setdcd(&bc->hdrv, !!(inb(LPT_STATUS(dev->base_addr))
					     & PAR96_DCD));
	}
}

/* --------------------------------------------------------------------- */

static void par96_interrupt(int irq, void *dev_id, struct pt_regs *regs)
{
	struct device *dev = (struct device *)dev_id;
	struct baycom_state *bc = (struct baycom_state *)dev->priv;

	if (!dev || !bc || bc->hdrv.magic != HDLCDRV_MAGIC)
		return;

	baycom_int_freq(bc);
	/*
	 * check if transmitter active
	 */
	if (hdlcdrv_ptt(&bc->hdrv))
		par96_tx(dev, bc);
	else {
		par96_rx(dev, bc);
		if (--bc->modem.arb_divider <= 0) {
			bc->modem.arb_divider = 6;
			sti();
			hdlcdrv_arbitrate(dev, &bc->hdrv);
		}
	}
	sti();
	hdlcdrv_transmitter(dev, &bc->hdrv);
	hdlcdrv_receiver(dev, &bc->hdrv);
}

/* --------------------------------------------------------------------- */

static int par96_check_lpt(unsigned int iobase)
{
	unsigned char b1,b2;
	int i;

	b1 = inb(LPT_DATA(iobase));
	b2 = inb(LPT_CONTROL(iobase));
	outb(0xaa, LPT_DATA(iobase));
	i = inb(LPT_DATA(iobase)) == 0xaa;
	outb(0x55, LPT_DATA(iobase));
	i &= inb(LPT_DATA(iobase)) == 0x55;
	outb(0x0a, LPT_CONTROL(iobase));
	i &= (inb(LPT_CONTROL(iobase)) & 0xf) == 0x0a;
	outb(0x05, LPT_CONTROL(iobase));
	i &= (inb(LPT_CONTROL(iobase)) & 0xf) == 0x05;
	outb(b1, LPT_DATA(iobase));
	outb(b2, LPT_CONTROL(iobase));
	return !i;
}

/* --------------------------------------------------------------------- */

static int par96_open(struct device *dev)
{
	struct baycom_state *bc = (struct baycom_state *)dev->priv;

	if (!dev || !bc)
		return -ENXIO;
	if (!dev->base_addr || dev->base_addr > 0x1000-PAR96_EXTENT ||
	    dev->irq < 2 || dev->irq > 15)
		return -ENXIO;
	if (check_region(dev->base_addr, PAR96_EXTENT))
		return -EACCES;
	memset(&bc->modem, 0, sizeof(bc->modem));
	bc->hdrv.par.bitrate = 9600;
	if (par96_check_lpt(dev->base_addr))
		return -EIO;
	/* disable interrupt */
	outb(0, LPT_CONTROL(dev->base_addr));
	 /* switch off PTT */
	outb(PAR96_PTT | PAR97_POWER, LPT_DATA(dev->base_addr));
	printk(KERN_INFO "%s: par96 at iobase 0x%lx irq %u options 0x%x\n",
	       bc_drvname, dev->base_addr, dev->irq, bc->options);
	if (request_irq(dev->irq, par96_interrupt, SA_INTERRUPT,
			"baycom_par96", dev))
		return -EBUSY;
	request_region(dev->base_addr, PAR96_EXTENT, "baycom_par96");
	/* enable interrupt */
	outb(LPT_IRQ_ENABLE, LPT_CONTROL(dev->base_addr));
	MOD_INC_USE_COUNT;
	return 0;
}

/* --------------------------------------------------------------------- */

static int par96_close(struct device *dev)
{
	struct baycom_state *bc = (struct baycom_state *)dev->priv;

	if (!dev || !bc)
		return -EINVAL;
	/* disable interrupt */
	outb(0, LPT_CONTROL(dev->base_addr));
	/* switch off PTT */
	outb(PAR96_PTT | PAR97_POWER, LPT_DATA(dev->base_addr));
	free_irq(dev->irq, dev);
	release_region(dev->base_addr, PAR96_EXTENT);
	printk(KERN_INFO "%s: close par96 at iobase 0x%lx irq %u\n",
	       bc_drvname, dev->base_addr, dev->irq);
	MOD_DEC_USE_COUNT;
	return 0;
}

/* --------------------------------------------------------------------- */
/*
 * ===================== hdlcdrv driver interface =========================
 */

/* --------------------------------------------------------------------- */

static int baycom_ioctl(struct device *dev, struct ifreq *ifr,
			struct hdlcdrv_ioctl *hi, int cmd);

/* --------------------------------------------------------------------- */

static struct hdlcdrv_ops ser12_ops = {
	bc_drvname,
	bc_drvinfo,
	ser12_open,
	ser12_close,
	baycom_ioctl
};

/* --------------------------------------------------------------------- */

static struct hdlcdrv_ops par96_ops = {
	bc_drvname,
	bc_drvinfo,
	par96_open,
	par96_close,
	baycom_ioctl
};

/* --------------------------------------------------------------------- */

static struct hdlcdrv_ops dummy_ops = {
	bc_drvname,
	bc_drvinfo,
	NULL,
	NULL,
	baycom_ioctl
};

/* --------------------------------------------------------------------- */

static int baycom_setmode(struct baycom_state *bc, char *modestr)
{
	struct hdlcdrv_ops *newops = NULL;
	unsigned long flags;

	if (!strncmp(modestr, "off", 3))
		newops = &dummy_ops;
	else if (!strncmp(modestr, "ser12", 5))
		newops = &ser12_ops;
	else if (!strncmp(modestr, "par96", 5))
		newops = &par96_ops;
	else
		return -EINVAL;
	save_flags(flags);
	cli();
	bc->hdrv.ops = newops;
	bc->options = !!strchr(modestr, '*');
	restore_flags(flags);
	return 0;
}

/* --------------------------------------------------------------------- */

static int baycom_ioctl(struct device *dev, struct ifreq *ifr,
			struct hdlcdrv_ioctl *hi, int cmd)
{
	struct baycom_state *bc;
	struct baycom_ioctl bi;
	int cmd2;

	if (!dev || !dev->priv ||
	    ((struct baycom_state *)dev->priv)->hdrv.magic != HDLCDRV_MAGIC) {
		printk(KERN_ERR "bc_ioctl: invalid device struct\n");
		return -EINVAL;
	}
	bc = (struct baycom_state *)dev->priv;

	if (cmd != SIOCDEVPRIVATE)
		return -ENOIOCTLCMD;
	if (get_user(cmd2, (int *)ifr->ifr_data))
		return -EFAULT;
	switch (hi->cmd) {
	default:
		break;

	case HDLCDRVCTL_GETMODE:
		if (bc->hdrv.ops == &ser12_ops)
			strcpy(hi->data.modename, "ser12");
		else if (bc->hdrv.ops == &par96_ops)
			strcpy(hi->data.modename, "par96");
		else if (bc->hdrv.ops == &dummy_ops)
			strcpy(hi->data.modename, "off");
		else
			strcpy(hi->data.modename, "invalid");
		if (bc->options & 1)
			strcat(hi->data.modename, "*");
		if (copy_to_user(ifr->ifr_data, hi, sizeof(struct hdlcdrv_ioctl)))
			return -EFAULT;
		return 0;

	case HDLCDRVCTL_SETMODE:
		if (!suser() || dev->start)
			return -EACCES;
		hi->data.modename[sizeof(hi->data.modename)-1] = '\0';
		return baycom_setmode(bc, hi->data.modename);

	case HDLCDRVCTL_MODELIST:
		strcpy(hi->data.modename, "ser12,par96");
		if (copy_to_user(ifr->ifr_data, hi, sizeof(struct hdlcdrv_ioctl)))
			return -EFAULT;
		return 0;

	case HDLCDRVCTL_MODEMPARMASK:
		return HDLCDRV_PARMASK_IOBASE | HDLCDRV_PARMASK_IRQ;

	}

	if (copy_from_user(&bi, ifr->ifr_data, sizeof(bi)))
		return -EFAULT;
	switch (bi.cmd) {
	default:
		return -ENOIOCTLCMD;

#ifdef BAYCOM_DEBUG
	case BAYCOMCTL_GETDEBUG:
		bi.data.dbg.debug1 = bc->hdrv.ptt_keyed;
		bi.data.dbg.debug2 = bc->debug_vals.last_intcnt;
		bi.data.dbg.debug3 = bc->debug_vals.last_pllcorr;
		break;
#endif /* BAYCOM_DEBUG */

	}
	if (copy_to_user(ifr->ifr_data, &bi, sizeof(bi)))
		return -EFAULT;
	return 0;

}

/* --------------------------------------------------------------------- */

__initfunc(int baycom_init(void))
{
	int i, j, found = 0;
	char set_hw = 1;
	struct baycom_state *bc;
	char ifname[HDLCDRV_IFNAMELEN];


	printk(bc_drvinfo);
	/*
	 * register net devices
	 */
	for (i = 0; i < NR_PORTS; i++) {
		struct device *dev = baycom_device+i;
		sprintf(ifname, "bc%d", i);

		if (!baycom_ports[i].mode)
			set_hw = 0;
		if (!set_hw)
			baycom_ports[i].iobase = baycom_ports[i].irq = 0;
		j = hdlcdrv_register_hdlcdrv(dev, &dummy_ops,
					     sizeof(struct baycom_state),
					     ifname, baycom_ports[i].iobase,
					     baycom_ports[i].irq, 0);
		if (!j) {
			bc = (struct baycom_state *)dev->priv;
			if (set_hw && baycom_setmode(bc, baycom_ports[i].mode))
				set_hw = 0;
			found++;
		} else {
			printk(KERN_WARNING "%s: cannot register net device\n",
			       bc_drvname);
		}
	}
	if (!found)
		return -ENXIO;
	return 0;
}

/* --------------------------------------------------------------------- */

#ifdef MODULE

/*
 * command line settable parameters
 */
static char *mode = NULL;
static int iobase = 0x3f8;
static int irq = 4;

#if LINUX_VERSION_CODE >= 0x20115

MODULE_PARM(mode, "s");
MODULE_PARM_DESC(mode, "baycom operating mode; eg. ser12* or par96");
MODULE_PARM(iobase, "i");
MODULE_PARM_DESC(iobase, "baycom io base address");
MODULE_PARM(irq, "i");
MODULE_PARM_DESC(irq, "baycom irq number");

MODULE_AUTHOR("Thomas M. Sailer, sailer@ife.ee.ethz.ch, hb9jnx@hb9w.che.eu");
MODULE_DESCRIPTION("Baycom ser12, par96 and picpar amateur radio modem driver");

#endif

__initfunc(int init_module(void))
{
	baycom_ports[0].mode = mode;
	baycom_ports[0].iobase = iobase;
	baycom_ports[0].irq = irq;
	baycom_ports[1].mode = NULL;

	return baycom_init();
}

/* --------------------------------------------------------------------- */

void cleanup_module(void)
{
	int i;

	for(i = 0; i < NR_PORTS; i++) {
		struct device *dev = baycom_device+i;
		struct baycom_state *bc = (struct baycom_state *)dev->priv;

		if (bc) {
			if (bc->hdrv.magic != HDLCDRV_MAGIC)
				printk(KERN_ERR "baycom: invalid magic in "
				       "cleanup_module\n");
			else
				hdlcdrv_unregister_hdlcdrv(dev);
		}
	}
}

#else /* MODULE */
/* --------------------------------------------------------------------- */
/*
 * format: baycom=io,irq,mode
 * mode: {ser12,par96}[*]
 * * indicates sofware DCD
 */

__initfunc(void baycom_setup(char *str, int *ints))
{
	int i;

	for (i = 0; (i < NR_PORTS) && (baycom_ports[i].mode); i++);
	if ((i >= NR_PORTS) || (ints[0] < 2)) {
		printk(KERN_INFO "%s: too many or invalid interface "
		       "specifications\n", bc_drvname);
		return;
	}
	baycom_ports[i].mode = str;
	baycom_ports[i].iobase = ints[1];
	baycom_ports[i].irq = ints[2];
	if (i < NR_PORTS-1)
		baycom_ports[i+1].mode = NULL;
}

#endif /* MODULE */
/* --------------------------------------------------------------------- */
