Import 2.1.36

[davej-history.git] / drivers / net / baycom.c

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

/*
 *      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 *          from Baycom) and has been replaced by the PICPAR modem (see below).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)
 */

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

#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>
#include <linux/init.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

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

#define BAYCOM_DEBUG

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

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

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 0.3 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 last_sample;
                        unsigned char interm_sample;
                        unsigned int bit_pll;
                        unsigned int dcd_shreg;
                        int dcd_sum0, dcd_sum1, dcd_sum2;
                        unsigned int dcd_time;
                        unsigned char last_rxbit;
                        unsigned char tx_bit;
                } 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 =========================
 */

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);
}

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

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");
        /*
         * 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]);
        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

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