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baycom_epp.c

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

/*
 *    baycom_epp.c  -- baycom epp radio modem driver.
 *
 *    Copyright (C) 1998-2000
 *          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.
 *
 *
 *  History:
 *   0.1  xx.xx.1998  Initial version by Matthias Welwarsky (dg2fef)
 *   0.2  21.04.1998  Massive rework by Thomas Sailer
 *                    Integrated FPGA EPP modem configuration routines
 *   0.3  11.05.1998  Took FPGA config out and moved it into a separate program
 *   0.4  26.07.1999  Adapted to new lowlevel parport driver interface
 *   0.5  03.08.1999  adapt to Linus' new __setup/__initcall
 *                    removed some pre-2.2 kernel compatibility cruft
 *   0.6  10.08.1999  Check if parport can do SPP and is safe to access during interrupt contexts
 *   0.7  12.02.2000  adapted to softnet driver interface
 *
 */

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

#include <linux/crc-ccitt.h>
#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/string.h>
#include <linux/workqueue.h>
#include <linux/fs.h>
#include <linux/parport.h>
#include <linux/if_arp.h>
#include <linux/hdlcdrv.h>
#include <linux/baycom.h>
#include <linux/jiffies.h>
#include <linux/random.h>
#include <net/ax25.h> 
#include <asm/uaccess.h>

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

#define BAYCOM_DEBUG
#define BAYCOM_MAGIC 19730510

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

static const char paranoia_str[] = KERN_ERR 
      "baycom_epp: bad magic number for hdlcdrv_state struct in routine %s\n";

static const char bc_drvname[] = "baycom_epp";
static const char bc_drvinfo[] = KERN_INFO "baycom_epp: (C) 1998-2000 Thomas Sailer, HB9JNX/AE4WA\n"
KERN_INFO "baycom_epp: version 0.7 compiled " __TIME__ " " __DATE__ "\n";

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

#define NR_PORTS 4

static struct net_device *baycom_device[NR_PORTS];

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

/* EPP status register */
#define EPP_DCDBIT      0x80
#define EPP_PTTBIT      0x08
#define EPP_NREF        0x01
#define EPP_NRAEF       0x02
#define EPP_NRHF        0x04
#define EPP_NTHF        0x20
#define EPP_NTAEF       0x10
#define EPP_NTEF        EPP_PTTBIT

/* EPP control register */
#define EPP_TX_FIFO_ENABLE 0x10
#define EPP_RX_FIFO_ENABLE 0x08
#define EPP_MODEM_ENABLE   0x20
#define EPP_LEDS           0xC0
#define EPP_IRQ_ENABLE     0x10

/* LPT registers */
#define LPTREG_ECONTROL       0x402
#define LPTREG_CONFIGB        0x401
#define LPTREG_CONFIGA        0x400
#define LPTREG_EPPDATA        0x004
#define LPTREG_EPPADDR        0x003
#define LPTREG_CONTROL        0x002
#define LPTREG_STATUS         0x001
#define LPTREG_DATA           0x000

/* LPT control register */
#define LPTCTRL_PROGRAM       0x04   /* 0 to reprogram */
#define LPTCTRL_WRITE         0x01
#define LPTCTRL_ADDRSTB       0x08
#define LPTCTRL_DATASTB       0x02
#define LPTCTRL_INTEN         0x10

/* LPT status register */
#define LPTSTAT_SHIFT_NINTR   6
#define LPTSTAT_WAIT          0x80
#define LPTSTAT_NINTR         (1<<LPTSTAT_SHIFT_NINTR)
#define LPTSTAT_PE            0x20
#define LPTSTAT_DONE          0x10
#define LPTSTAT_NERROR        0x08
#define LPTSTAT_EPPTIMEOUT    0x01

/* LPT data register */
#define LPTDATA_SHIFT_TDI     0
#define LPTDATA_SHIFT_TMS     2
#define LPTDATA_TDI           (1<<LPTDATA_SHIFT_TDI)
#define LPTDATA_TCK           0x02
#define LPTDATA_TMS           (1<<LPTDATA_SHIFT_TMS)
#define LPTDATA_INITBIAS      0x80


/* EPP modem config/status bits */
#define EPP_DCDBIT            0x80
#define EPP_PTTBIT            0x08
#define EPP_RXEBIT            0x01
#define EPP_RXAEBIT           0x02
#define EPP_RXHFULL           0x04

#define EPP_NTHF              0x20
#define EPP_NTAEF             0x10
#define EPP_NTEF              EPP_PTTBIT

#define EPP_TX_FIFO_ENABLE    0x10
#define EPP_RX_FIFO_ENABLE    0x08
#define EPP_MODEM_ENABLE      0x20
#define EPP_LEDS              0xC0
#define EPP_IRQ_ENABLE        0x10

/* Xilinx 4k JTAG instructions */
#define XC4K_IRLENGTH   3
#define XC4K_EXTEST     0
#define XC4K_PRELOAD    1
#define XC4K_CONFIGURE  5
#define XC4K_BYPASS     7

#define EPP_CONVENTIONAL  0
#define EPP_FPGA          1
#define EPP_FPGAEXTSTATUS 2

#define TXBUFFER_SIZE     ((HDLCDRV_MAXFLEN*6/5)+8)

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

struct baycom_state {
      int magic;

        struct pardevice *pdev;
      struct net_device *dev;
      unsigned int work_running;
      struct delayed_work run_work;
      unsigned int modem;
      unsigned int bitrate;
      unsigned char stat;

      struct {
            unsigned int intclk;
            unsigned int fclk;
            unsigned int bps;
            unsigned int extmodem;
            unsigned int loopback;
      } cfg;

        struct hdlcdrv_channel_params ch_params;

        struct {
            unsigned int bitbuf, bitstream, numbits, state;
            unsigned char *bufptr;
            int bufcnt;
            unsigned char buf[TXBUFFER_SIZE];
        } hdlcrx;

        struct {
            int calibrate;
                int slotcnt;
            int flags;
            enum { tx_idle = 0, tx_keyup, tx_data, tx_tail } state;
            unsigned char *bufptr;
            int bufcnt;
            unsigned char buf[TXBUFFER_SIZE];
        } hdlctx;

        struct net_device_stats stats;
      unsigned int ptt_keyed;
      struct sk_buff *skb;  /* next transmit packet  */

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

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

#define KISS_VERBOSE

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

#define PARAM_TXDELAY   1
#define PARAM_PERSIST   2
#define PARAM_SLOTTIME  3
#define PARAM_TXTAIL    4
#define PARAM_FULLDUP   5
#define PARAM_HARDWARE  6
#define PARAM_RETURN    255

/* --------------------------------------------------------------------- */
/*
 * the CRC routines are stolen from WAMPES
 * by Dieter Deyke
 */


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

#if 0
static inline void append_crc_ccitt(unsigned char *buffer, int len)
{
      unsigned int crc = 0xffff;

      for (;len>0;len--)
            crc = (crc >> 8) ^ crc_ccitt_table[(crc ^ *buffer++) & 0xff];
      crc ^= 0xffff;
      *buffer++ = crc;
      *buffer++ = crc >> 8;
}
#endif

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

static inline int check_crc_ccitt(const unsigned char *buf, int cnt)
{
      return (crc_ccitt(0xffff, buf, cnt) & 0xffff) == 0xf0b8;
}

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

static inline int calc_crc_ccitt(const unsigned char *buf, int cnt)
{
      return (crc_ccitt(0xffff, buf, cnt) ^ 0xffff) & 0xffff;
}

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

#define tenms_to_flags(bc,tenms) ((tenms * bc->bitrate) / 800)

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

static inline void 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 (time_after_eq(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 */
}

/* ---------------------------------------------------------------------- */
/*
 *    eppconfig_path should be setable  via /proc/sys.
 */

static char eppconfig_path[256] = "/usr/sbin/eppfpga";

static char *envp[] = { "HOME=/", "TERM=linux", "PATH=/usr/bin:/bin", NULL };

/* eppconfig: called during ifconfig up to configure the modem */
static int eppconfig(struct baycom_state *bc)
{
      char modearg[256];
      char portarg[16];
        char *argv[] = { eppconfig_path, "-s", "-p", portarg, "-m", modearg,
                   NULL };

      /* set up arguments */
      sprintf(modearg, "%sclk,%smodem,fclk=%d,bps=%d,divider=%d%s,extstat",
            bc->cfg.intclk ? "int" : "ext",
            bc->cfg.extmodem ? "ext" : "int", bc->cfg.fclk, bc->cfg.bps,
            (bc->cfg.fclk + 8 * bc->cfg.bps) / (16 * bc->cfg.bps),
            bc->cfg.loopback ? ",loopback" : "");
      sprintf(portarg, "%ld", bc->pdev->port->base);
      printk(KERN_DEBUG "%s: %s -s -p %s -m %s\n", bc_drvname, eppconfig_path, portarg, modearg);

      return call_usermodehelper(eppconfig_path, argv, envp, UMH_WAIT_PROC);
}

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

static inline void do_kiss_params(struct baycom_state *bc,
                          unsigned char *data, unsigned long len)
{

#ifdef KISS_VERBOSE
#define PKP(a,b) printk(KERN_INFO "baycomm_epp: channel params: " a "\n", b)
#else /* KISS_VERBOSE */            
#define PKP(a,b) 
#endif /* KISS_VERBOSE */           

      if (len < 2)
            return;
      switch(data[0]) {
      case PARAM_TXDELAY:
            bc->ch_params.tx_delay = data[1];
            PKP("TX delay = %ums", 10 * bc->ch_params.tx_delay);
            break;
      case PARAM_PERSIST:   
            bc->ch_params.ppersist = data[1];
            PKP("p persistence = %u", bc->ch_params.ppersist);
            break;
      case PARAM_SLOTTIME:  
            bc->ch_params.slottime = data[1];
            PKP("slot time = %ums", bc->ch_params.slottime);
            break;
      case PARAM_TXTAIL:    
            bc->ch_params.tx_tail = data[1];
            PKP("TX tail = %ums", bc->ch_params.tx_tail);
            break;
      case PARAM_FULLDUP:   
            bc->ch_params.fulldup = !!data[1];
            PKP("%s duplex", bc->ch_params.fulldup ? "full" : "half");
            break;
      default:
            break;
      }
#undef PKP
}

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

static void encode_hdlc(struct baycom_state *bc)
{
      struct sk_buff *skb;
      unsigned char *wp, *bp;
      int pkt_len;
        unsigned bitstream, notbitstream, bitbuf, numbit, crc;
      unsigned char crcarr[2];
      int j;
      
      if (bc->hdlctx.bufcnt > 0)
            return;
      skb = bc->skb;
      if (!skb)
            return;
      bc->skb = NULL;
      pkt_len = skb->len-1; /* strip KISS byte */
      wp = bc->hdlctx.buf;
      bp = skb->data+1;
      crc = calc_crc_ccitt(bp, pkt_len);
      crcarr[0] = crc;
      crcarr[1] = crc >> 8;
      *wp++ = 0x7e;
      bitstream = bitbuf = numbit = 0;
      while (pkt_len > -2) {
            bitstream >>= 8;
            bitstream |= ((unsigned int)*bp) << 8;
            bitbuf |= ((unsigned int)*bp) << numbit;
            notbitstream = ~bitstream;
            bp++;
            pkt_len--;
            if (!pkt_len)
                  bp = crcarr;
            for (j = 0; j < 8; j++)
                  if (unlikely(!(notbitstream & (0x1f0 << j)))) {
                        bitstream &= ~(0x100 << j);
                        bitbuf = (bitbuf & (((2 << j) << numbit) - 1)) |
                              ((bitbuf & ~(((2 << j) << numbit) - 1)) << 1);
                        numbit++;
                        notbitstream = ~bitstream;
                  }
            numbit += 8;
            while (numbit >= 8) {
                  *wp++ = bitbuf;
                  bitbuf >>= 8;
                  numbit -= 8;
            }
      }
      bitbuf |= 0x7e7e << numbit;
      numbit += 16;
      while (numbit >= 8) {
            *wp++ = bitbuf;
            bitbuf >>= 8;
            numbit -= 8;
      }
      bc->hdlctx.bufptr = bc->hdlctx.buf;
      bc->hdlctx.bufcnt = wp - bc->hdlctx.buf;
      dev_kfree_skb(skb);
      bc->stats.tx_packets++;
}

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

static int transmit(struct baycom_state *bc, int cnt, unsigned char stat)
{
      struct parport *pp = bc->pdev->port;
      unsigned char tmp[128];
      int i, j;

      if (bc->hdlctx.state == tx_tail && !(stat & EPP_PTTBIT))
            bc->hdlctx.state = tx_idle;
      if (bc->hdlctx.state == tx_idle && bc->hdlctx.calibrate <= 0) {
            if (bc->hdlctx.bufcnt <= 0)
                  encode_hdlc(bc);
            if (bc->hdlctx.bufcnt <= 0)
                  return 0;
            if (!bc->ch_params.fulldup) {
                  if (!(stat & EPP_DCDBIT)) {
                        bc->hdlctx.slotcnt = bc->ch_params.slottime;
                        return 0;
                  }
                  if ((--bc->hdlctx.slotcnt) > 0)
                        return 0;
                  bc->hdlctx.slotcnt = bc->ch_params.slottime;
                  if ((random32() % 256) > bc->ch_params.ppersist)
                        return 0;
            }
      }
      if (bc->hdlctx.state == tx_idle && bc->hdlctx.bufcnt > 0) {
            bc->hdlctx.state = tx_keyup;
            bc->hdlctx.flags = tenms_to_flags(bc, bc->ch_params.tx_delay);
            bc->ptt_keyed++;
      }
      while (cnt > 0) {
            switch (bc->hdlctx.state) {
            case tx_keyup:
                  i = min_t(int, cnt, bc->hdlctx.flags);
                  cnt -= i;
                  bc->hdlctx.flags -= i;
                  if (bc->hdlctx.flags <= 0)
                        bc->hdlctx.state = tx_data;
                  memset(tmp, 0x7e, sizeof(tmp));
                  while (i > 0) {
                        j = (i > sizeof(tmp)) ? sizeof(tmp) : i;
                        if (j != pp->ops->epp_write_data(pp, tmp, j, 0))
                              return -1;
                        i -= j;
                  }
                  break;

            case tx_data:
                  if (bc->hdlctx.bufcnt <= 0) {
                        encode_hdlc(bc);
                        if (bc->hdlctx.bufcnt <= 0) {
                              bc->hdlctx.state = tx_tail;
                              bc->hdlctx.flags = tenms_to_flags(bc, bc->ch_params.tx_tail);
                              break;
                        }
                  }
                  i = min_t(int, cnt, bc->hdlctx.bufcnt);
                  bc->hdlctx.bufcnt -= i;
                  cnt -= i;
                  if (i != pp->ops->epp_write_data(pp, bc->hdlctx.bufptr, i, 0))
                              return -1;
                  bc->hdlctx.bufptr += i;
                  break;
                  
            case tx_tail:
                  encode_hdlc(bc);
                  if (bc->hdlctx.bufcnt > 0) {
                        bc->hdlctx.state = tx_data;
                        break;
                  }
                  i = min_t(int, cnt, bc->hdlctx.flags);
                  if (i) {
                        cnt -= i;
                        bc->hdlctx.flags -= i;
                        memset(tmp, 0x7e, sizeof(tmp));
                        while (i > 0) {
                              j = (i > sizeof(tmp)) ? sizeof(tmp) : i;
                              if (j != pp->ops->epp_write_data(pp, tmp, j, 0))
                                    return -1;
                              i -= j;
                        }
                        break;
                  }

            default:  /* fall through */
                  if (bc->hdlctx.calibrate <= 0)
                        return 0;
                  i = min_t(int, cnt, bc->hdlctx.calibrate);
                  cnt -= i;
                  bc->hdlctx.calibrate -= i;
                  memset(tmp, 0, sizeof(tmp));
                  while (i > 0) {
                        j = (i > sizeof(tmp)) ? sizeof(tmp) : i;
                        if (j != pp->ops->epp_write_data(pp, tmp, j, 0))
                              return -1;
                        i -= j;
                  }
                  break;
            }
      }
      return 0;
}

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

static void do_rxpacket(struct net_device *dev)
{
      struct baycom_state *bc = netdev_priv(dev);
      struct sk_buff *skb;
      unsigned char *cp;
      unsigned pktlen;

      if (bc->hdlcrx.bufcnt < 4) 
            return;
      if (!check_crc_ccitt(bc->hdlcrx.buf, bc->hdlcrx.bufcnt)) 
            return;
      pktlen = bc->hdlcrx.bufcnt-2+1; /* KISS kludge */
      if (!(skb = dev_alloc_skb(pktlen))) {
            printk("%s: memory squeeze, dropping packet\n", dev->name);
            bc->stats.rx_dropped++;
            return;
      }
      cp = skb_put(skb, pktlen);
      *cp++ = 0; /* KISS kludge */
      memcpy(cp, bc->hdlcrx.buf, pktlen - 1);
      skb->protocol = ax25_type_trans(skb, dev);
      netif_rx(skb);
      dev->last_rx = jiffies;
      bc->stats.rx_packets++;
}

static int receive(struct net_device *dev, int cnt)
{
      struct baycom_state *bc = netdev_priv(dev);
      struct parport *pp = bc->pdev->port;
        unsigned int bitbuf, notbitstream, bitstream, numbits, state;
      unsigned char tmp[128];
        unsigned char *cp;
      int cnt2, ret = 0;
      int j;
        
        numbits = bc->hdlcrx.numbits;
      state = bc->hdlcrx.state;
      bitstream = bc->hdlcrx.bitstream;
      bitbuf = bc->hdlcrx.bitbuf;
      while (cnt > 0) {
            cnt2 = (cnt > sizeof(tmp)) ? sizeof(tmp) : cnt;
            cnt -= cnt2;
            if (cnt2 != pp->ops->epp_read_data(pp, tmp, cnt2, 0)) {
                  ret = -1;
                  break;
            }
            cp = tmp;
            for (; cnt2 > 0; cnt2--, cp++) {
                  bitstream >>= 8;
                  bitstream |= (*cp) << 8;
                  bitbuf >>= 8;
                  bitbuf |= (*cp) << 8;
                  numbits += 8;
                  notbitstream = ~bitstream;
                  for (j = 0; j < 8; j++) {

                        /* flag or abort */
                          if (unlikely(!(notbitstream & (0x0fc << j)))) {

                              /* abort received */
                              if (!(notbitstream & (0x1fc << j)))
                                    state = 0;

                              /* not flag received */
                              else if (!(bitstream & (0x1fe << j)) != (0x0fc << j)) {
                                    if (state)
                                          do_rxpacket(dev);
                                    bc->hdlcrx.bufcnt = 0;
                                    bc->hdlcrx.bufptr = bc->hdlcrx.buf;
                                    state = 1;
                                    numbits = 7-j;
                                    }
                              }

                        /* stuffed bit */
                        else if (unlikely((bitstream & (0x1f8 << j)) == (0xf8 << j))) {
                              numbits--;
                              bitbuf = (bitbuf & ((~0xff) << j)) | ((bitbuf & ~((~0xff) << j)) << 1);
                              }
                        }
                  while (state && numbits >= 8) {
                        if (bc->hdlcrx.bufcnt >= TXBUFFER_SIZE) {
                              state = 0;
                        } else {
                              *(bc->hdlcrx.bufptr)++ = bitbuf >> (16-numbits);
                              bc->hdlcrx.bufcnt++;
                              numbits -= 8;
                        }
                  }
            }
      }
        bc->hdlcrx.numbits = numbits;
      bc->hdlcrx.state = state;
      bc->hdlcrx.bitstream = bitstream;
      bc->hdlcrx.bitbuf = bitbuf;
      return ret;
}

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

#ifdef __i386__
#include <asm/msr.h>
#define GETTICK(x)                                                \
({                                                                \
      if (cpu_has_tsc)                                          \
            rdtscl(x);                                        \
})
#else /* __i386__ */
#define GETTICK(x)
#endif /* __i386__ */

static void epp_bh(struct work_struct *work)
{
      struct net_device *dev;
      struct baycom_state *bc;
      struct parport *pp;
      unsigned char stat;
      unsigned char tmp[2];
      unsigned int time1 = 0, time2 = 0, time3 = 0;
      int cnt, cnt2;

      bc = container_of(work, struct baycom_state, run_work.work);
      dev = bc->dev;
      if (!bc->work_running)
            return;
      baycom_int_freq(bc);
      pp = bc->pdev->port;
      /* update status */
      if (pp->ops->epp_read_addr(pp, &stat, 1, 0) != 1)
            goto epptimeout;
      bc->stat = stat;
      bc->debug_vals.last_pllcorr = stat;
      GETTICK(time1);
      if (bc->modem == EPP_FPGAEXTSTATUS) {
            /* get input count */
            tmp[0] = EPP_TX_FIFO_ENABLE|EPP_RX_FIFO_ENABLE|EPP_MODEM_ENABLE|1;
            if (pp->ops->epp_write_addr(pp, tmp, 1, 0) != 1)
                  goto epptimeout;
            if (pp->ops->epp_read_addr(pp, tmp, 2, 0) != 2)
                  goto epptimeout;
            cnt = tmp[0] | (tmp[1] << 8);
            cnt &= 0x7fff;
            /* get output count */
            tmp[0] = EPP_TX_FIFO_ENABLE|EPP_RX_FIFO_ENABLE|EPP_MODEM_ENABLE|2;
            if (pp->ops->epp_write_addr(pp, tmp, 1, 0) != 1)
                  goto epptimeout;
            if (pp->ops->epp_read_addr(pp, tmp, 2, 0) != 2)
                  goto epptimeout;
            cnt2 = tmp[0] | (tmp[1] << 8);
            cnt2 = 16384 - (cnt2 & 0x7fff);
            /* return to normal */
            tmp[0] = EPP_TX_FIFO_ENABLE|EPP_RX_FIFO_ENABLE|EPP_MODEM_ENABLE;
            if (pp->ops->epp_write_addr(pp, tmp, 1, 0) != 1)
                  goto epptimeout;
            if (transmit(bc, cnt2, stat))
                  goto epptimeout;
            GETTICK(time2);
            if (receive(dev, cnt))
                  goto epptimeout;
            if (pp->ops->epp_read_addr(pp, &stat, 1, 0) != 1)
                  goto epptimeout;
            bc->stat = stat;
      } else {
            /* try to tx */
            switch (stat & (EPP_NTAEF|EPP_NTHF)) {
            case EPP_NTHF:
                  cnt = 2048 - 256;
                  break;
            
            case EPP_NTAEF:
                  cnt = 2048 - 1793;
                  break;
            
            case 0:
                  cnt = 0;
                  break;
            
            default:
                  cnt = 2048 - 1025;
                  break;
            }
            if (transmit(bc, cnt, stat))
                  goto epptimeout;
            GETTICK(time2);
            /* do receiver */
            while ((stat & (EPP_NRAEF|EPP_NRHF)) != EPP_NRHF) {
                  switch (stat & (EPP_NRAEF|EPP_NRHF)) {
                  case EPP_NRAEF:
                        cnt = 1025;
                        break;

                  case 0:
                        cnt = 1793;
                        break;

                  default:
                        cnt = 256;
                        break;
                  }
                  if (receive(dev, cnt))
                        goto epptimeout;
                  if (pp->ops->epp_read_addr(pp, &stat, 1, 0) != 1)
                        goto epptimeout;
            }
            cnt = 0;
            if (bc->bitrate < 50000)
                  cnt = 256;
            else if (bc->bitrate < 100000)
                  cnt = 128;
            while (cnt > 0 && stat & EPP_NREF) {
                  if (receive(dev, 1))
                        goto epptimeout;
                  cnt--;
                  if (pp->ops->epp_read_addr(pp, &stat, 1, 0) != 1)
                        goto epptimeout;
            }
      }
      GETTICK(time3);
#ifdef BAYCOM_DEBUG
      bc->debug_vals.mod_cycles = time2 - time1;
      bc->debug_vals.demod_cycles = time3 - time2;
#endif /* BAYCOM_DEBUG */
      schedule_delayed_work(&bc->run_work, 1);
      if (!bc->skb)
            netif_wake_queue(dev);
      return;
 epptimeout:
      printk(KERN_ERR "%s: EPP timeout!\n", bc_drvname);
}

/* ---------------------------------------------------------------------- */
/*
 * ===================== network driver interface =========================
 */

static int baycom_send_packet(struct sk_buff *skb, struct net_device *dev)
{
      struct baycom_state *bc = netdev_priv(dev);

      if (skb->data[0] != 0) {
            do_kiss_params(bc, skb->data, skb->len);
            dev_kfree_skb(skb);
            return 0;
      }
      if (bc->skb)
            return -1;
      /* strip KISS byte */
      if (skb->len >= HDLCDRV_MAXFLEN+1 || skb->len < 3) {
            dev_kfree_skb(skb);
            return 0;
      }
      netif_stop_queue(dev);
      bc->skb = skb;
      return 0;
}

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

static int baycom_set_mac_address(struct net_device *dev, void *addr)
{
      struct sockaddr *sa = (struct sockaddr *)addr;

      /* addr is an AX.25 shifted ASCII mac address */
      memcpy(dev->dev_addr, sa->sa_data, dev->addr_len); 
      return 0;                                         
}

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

static struct net_device_stats *baycom_get_stats(struct net_device *dev)
{
      struct baycom_state *bc = netdev_priv(dev);

      /* 
       * Get the current statistics.  This may be called with the
       * card open or closed. 
       */
      return &bc->stats;
}

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

static void epp_wakeup(void *handle)
{
        struct net_device *dev = (struct net_device *)handle;
        struct baycom_state *bc = netdev_priv(dev);

        printk(KERN_DEBUG "baycom_epp: %s: why am I being woken up?\n", dev->name);
        if (!parport_claim(bc->pdev))
                printk(KERN_DEBUG "baycom_epp: %s: I'm broken.\n", dev->name);
}

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

/*
 * Open/initialize the board. This is called (in the current kernel)
 * sometime after booting when the 'ifconfig' program is run.
 *
 * This routine should set everything up anew at each open, even
 * registers that "should" only need to be set once at boot, so that
 * there is non-reboot way to recover if something goes wrong.
 */

static int epp_open(struct net_device *dev)
{
      struct baycom_state *bc = netdev_priv(dev);
        struct parport *pp = parport_find_base(dev->base_addr);
      unsigned int i, j;
      unsigned char tmp[128];
      unsigned char stat;
      unsigned long tstart;
      
        if (!pp) {
                printk(KERN_ERR "%s: parport at 0x%lx unknown\n", bc_drvname, dev->base_addr);
                return -ENXIO;
        }
#if 0
        if (pp->irq < 0) {
                printk(KERN_ERR "%s: parport at 0x%lx has no irq\n", bc_drvname, pp->base);
            parport_put_port(pp);
                return -ENXIO;
        }
#endif
      if ((~pp->modes) & (PARPORT_MODE_TRISTATE | PARPORT_MODE_PCSPP | PARPORT_MODE_SAFEININT)) {
                printk(KERN_ERR "%s: parport at 0x%lx cannot be used\n",
                   bc_drvname, pp->base);
            parport_put_port(pp);
                return -EIO;
      }
      memset(&bc->modem, 0, sizeof(bc->modem));
        bc->pdev = parport_register_device(pp, dev->name, NULL, epp_wakeup, 
                                 NULL, PARPORT_DEV_EXCL, dev);
      parport_put_port(pp);
        if (!bc->pdev) {
                printk(KERN_ERR "%s: cannot register parport at 0x%lx\n", bc_drvname, pp->base);
                return -ENXIO;
        }
        if (parport_claim(bc->pdev)) {
                printk(KERN_ERR "%s: parport at 0x%lx busy\n", bc_drvname, pp->base);
                parport_unregister_device(bc->pdev);
                return -EBUSY;
        }
        dev->irq = /*pp->irq*/ 0;
      INIT_DELAYED_WORK(&bc->run_work, epp_bh);
      bc->work_running = 1;
      bc->modem = EPP_CONVENTIONAL;
      if (eppconfig(bc))
            printk(KERN_INFO "%s: no FPGA detected, assuming conventional EPP modem\n", bc_drvname);
      else
            bc->modem = /*EPP_FPGA*/ EPP_FPGAEXTSTATUS;
      parport_write_control(pp, LPTCTRL_PROGRAM); /* prepare EPP mode; we aren't using interrupts */
      /* reset the modem */
      tmp[0] = 0;
      tmp[1] = EPP_TX_FIFO_ENABLE|EPP_RX_FIFO_ENABLE|EPP_MODEM_ENABLE;
      if (pp->ops->epp_write_addr(pp, tmp, 2, 0) != 2)
            goto epptimeout;
      /* autoprobe baud rate */
      tstart = jiffies;
      i = 0;
      while (time_before(jiffies, tstart + HZ/3)) {
            if (pp->ops->epp_read_addr(pp, &stat, 1, 0) != 1)
                  goto epptimeout;
            if ((stat & (EPP_NRAEF|EPP_NRHF)) == EPP_NRHF) {
                  schedule();
                  continue;
            }
            if (pp->ops->epp_read_data(pp, tmp, 128, 0) != 128)
                  goto epptimeout;
            if (pp->ops->epp_read_data(pp, tmp, 128, 0) != 128)
                  goto epptimeout;
            i += 256;
      }
      for (j = 0; j < 256; j++) {
            if (pp->ops->epp_read_addr(pp, &stat, 1, 0) != 1)
                  goto epptimeout;
            if (!(stat & EPP_NREF))
                  break;
            if (pp->ops->epp_read_data(pp, tmp, 1, 0) != 1)
                  goto epptimeout;
            i++;
      }
      tstart = jiffies - tstart;
      bc->bitrate = i * (8 * HZ) / tstart;
      j = 1;
      i = bc->bitrate >> 3;
      while (j < 7 && i > 150) {
            j++;
            i >>= 1;
      }
      printk(KERN_INFO "%s: autoprobed bitrate: %d  int divider: %d  int rate: %d\n", 
             bc_drvname, bc->bitrate, j, bc->bitrate >> (j+2));
      tmp[0] = EPP_TX_FIFO_ENABLE|EPP_RX_FIFO_ENABLE|EPP_MODEM_ENABLE/*|j*/;
      if (pp->ops->epp_write_addr(pp, tmp, 1, 0) != 1)
            goto epptimeout;
      /*
       * initialise hdlc variables
       */
      bc->hdlcrx.state = 0;
      bc->hdlcrx.numbits = 0;
      bc->hdlctx.state = tx_idle;
      bc->hdlctx.bufcnt = 0;
      bc->hdlctx.slotcnt = bc->ch_params.slottime;
      bc->hdlctx.calibrate = 0;
      /* start the bottom half stuff */
      schedule_delayed_work(&bc->run_work, 1);
      netif_start_queue(dev);
      return 0;

 epptimeout:
      printk(KERN_ERR "%s: epp timeout during bitrate probe\n", bc_drvname);
      parport_write_control(pp, 0); /* reset the adapter */
        parport_release(bc->pdev);
        parport_unregister_device(bc->pdev);
      return -EIO;
}

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

static int epp_close(struct net_device *dev)
{
      struct baycom_state *bc = netdev_priv(dev);
      struct parport *pp = bc->pdev->port;
      unsigned char tmp[1];

      bc->work_running = 0;
      flush_scheduled_work();
      bc->stat = EPP_DCDBIT;
      tmp[0] = 0;
      pp->ops->epp_write_addr(pp, tmp, 1, 0);
      parport_write_control(pp, 0); /* reset the adapter */
        parport_release(bc->pdev);
        parport_unregister_device(bc->pdev);
      if (bc->skb)
            dev_kfree_skb(bc->skb);
      bc->skb = NULL;
      printk(KERN_INFO "%s: close epp at iobase 0x%lx irq %u\n",
             bc_drvname, dev->base_addr, dev->irq);
      return 0;
}

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

static int baycom_setmode(struct baycom_state *bc, const char *modestr)
{
      const char *cp;

      if (strstr(modestr,"intclk"))
            bc->cfg.intclk = 1;
      if (strstr(modestr,"extclk"))
            bc->cfg.intclk = 0;
      if (strstr(modestr,"intmodem"))
            bc->cfg.extmodem = 0;
      if (strstr(modestr,"extmodem"))
            bc->cfg.extmodem = 1;
      if (strstr(modestr,"noloopback"))
            bc->cfg.loopback = 0;
      if (strstr(modestr,"loopback"))
            bc->cfg.loopback = 1;
      if ((cp = strstr(modestr,"fclk="))) {
            bc->cfg.fclk = simple_strtoul(cp+5, NULL, 0);
            if (bc->cfg.fclk < 1000000)
                  bc->cfg.fclk = 1000000;
            if (bc->cfg.fclk > 25000000)
                  bc->cfg.fclk = 25000000;
      }
      if ((cp = strstr(modestr,"bps="))) {
            bc->cfg.bps = simple_strtoul(cp+4, NULL, 0);
            if (bc->cfg.bps < 1000)
                  bc->cfg.bps = 1000;
            if (bc->cfg.bps > 1500000)
                  bc->cfg.bps = 1500000;
      }
      return 0;
}

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

static int baycom_ioctl(struct net_device *dev, struct ifreq *ifr, int cmd)
{
      struct baycom_state *bc = netdev_priv(dev);
      struct hdlcdrv_ioctl hi;

      if (cmd != SIOCDEVPRIVATE)
            return -ENOIOCTLCMD;

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

      case HDLCDRVCTL_GETCHANNELPAR:
            hi.data.cp.tx_delay = bc->ch_params.tx_delay;
            hi.data.cp.tx_tail = bc->ch_params.tx_tail;
            hi.data.cp.slottime = bc->ch_params.slottime;
            hi.data.cp.ppersist = bc->ch_params.ppersist;
            hi.data.cp.fulldup = bc->ch_params.fulldup;
            break;

      case HDLCDRVCTL_SETCHANNELPAR:
            if (!capable(CAP_NET_ADMIN))
                  return -EACCES;
            bc->ch_params.tx_delay = hi.data.cp.tx_delay;
            bc->ch_params.tx_tail = hi.data.cp.tx_tail;
            bc->ch_params.slottime = hi.data.cp.slottime;
            bc->ch_params.ppersist = hi.data.cp.ppersist;
            bc->ch_params.fulldup = hi.data.cp.fulldup;
            bc->hdlctx.slotcnt = 1;
            return 0;
            
      case HDLCDRVCTL_GETMODEMPAR:
            hi.data.mp.iobase = dev->base_addr;
            hi.data.mp.irq = dev->irq;
            hi.data.mp.dma = dev->dma;
            hi.data.mp.dma2 = 0;
            hi.data.mp.seriobase = 0;
            hi.data.mp.pariobase = 0;
            hi.data.mp.midiiobase = 0;
            break;

      case HDLCDRVCTL_SETMODEMPAR:
            if ((!capable(CAP_SYS_RAWIO)) || netif_running(dev))
                  return -EACCES;
            dev->base_addr = hi.data.mp.iobase;
            dev->irq = /*hi.data.mp.irq*/0;
            dev->dma = /*hi.data.mp.dma*/0;
            return 0;   
            
      case HDLCDRVCTL_GETSTAT:
            hi.data.cs.ptt = !!(bc->stat & EPP_PTTBIT);
            hi.data.cs.dcd = !(bc->stat & EPP_DCDBIT);
            hi.data.cs.ptt_keyed = bc->ptt_keyed;
            hi.data.cs.tx_packets = bc->stats.tx_packets;
            hi.data.cs.tx_errors = bc->stats.tx_errors;
            hi.data.cs.rx_packets = bc->stats.rx_packets;
            hi.data.cs.rx_errors = bc->stats.rx_errors;
            break;            

      case HDLCDRVCTL_OLDGETSTAT:
            hi.data.ocs.ptt = !!(bc->stat & EPP_PTTBIT);
            hi.data.ocs.dcd = !(bc->stat & EPP_DCDBIT);
            hi.data.ocs.ptt_keyed = bc->ptt_keyed;
            break;            

      case HDLCDRVCTL_CALIBRATE:
            if (!capable(CAP_SYS_RAWIO))
                  return -EACCES;
            bc->hdlctx.calibrate = hi.data.calibrate * bc->bitrate / 8;
            return 0;

      case HDLCDRVCTL_DRIVERNAME:
            strncpy(hi.data.drivername, "baycom_epp", sizeof(hi.data.drivername));
            break;
            
      case HDLCDRVCTL_GETMODE:
            sprintf(hi.data.modename, "%sclk,%smodem,fclk=%d,bps=%d%s", 
                  bc->cfg.intclk ? "int" : "ext",
                  bc->cfg.extmodem ? "ext" : "int", bc->cfg.fclk, bc->cfg.bps,
                  bc->cfg.loopback ? ",loopback" : "");
            break;

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

      case HDLCDRVCTL_MODELIST:
            strncpy(hi.data.modename, "intclk,extclk,intmodem,extmodem,divider=x",
                  sizeof(hi.data.modename));
            break;

      case HDLCDRVCTL_MODEMPARMASK:
            return HDLCDRV_PARMASK_IOBASE;

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

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

/*
 * Check for a network adaptor of this type, and return '0' if one exists.
 * If dev->base_addr == 0, probe all likely locations.
 * If dev->base_addr == 1, always return failure.
 * If dev->base_addr == 2, allocate space for the device and return success
 * (detachable devices only).
 */
static void baycom_probe(struct net_device *dev)
{
      const struct hdlcdrv_channel_params dflt_ch_params = { 
            20, 2, 10, 40, 0 
      };
      struct baycom_state *bc;

      /*
       * not a real probe! only initialize data structures
       */
      bc = netdev_priv(dev);
      /*
       * initialize the baycom_state struct
       */
      bc->ch_params = dflt_ch_params;
      bc->ptt_keyed = 0;

      /*
       * initialize the device struct
       */
      dev->open = epp_open;
      dev->stop = epp_close;
      dev->do_ioctl = baycom_ioctl;
      dev->hard_start_xmit = baycom_send_packet;
      dev->get_stats = baycom_get_stats;

      /* Fill in the fields of the device structure */
      bc->skb = NULL;
      
      dev->header_ops = &ax25_header_ops;
      dev->set_mac_address = baycom_set_mac_address;
      
      dev->type = ARPHRD_AX25;           /* AF_AX25 device */
      dev->hard_header_len = AX25_MAX_HEADER_LEN + AX25_BPQ_HEADER_LEN;
      dev->mtu = AX25_DEF_PACLEN;        /* eth_mtu is the default */
      dev->addr_len = AX25_ADDR_LEN;     /* sizeof an ax.25 address */
      memcpy(dev->broadcast, &ax25_bcast, AX25_ADDR_LEN);
      memcpy(dev->dev_addr, &null_ax25_address, AX25_ADDR_LEN);
      dev->tx_queue_len = 16;

      /* New style flags */
      dev->flags = 0;
}

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

/*
 * command line settable parameters
 */
static const char *mode[NR_PORTS] = { "", };
static int iobase[NR_PORTS] = { 0x378, };

module_param_array(mode, charp, NULL, 0);
MODULE_PARM_DESC(mode, "baycom operating mode");
module_param_array(iobase, int, NULL, 0);
MODULE_PARM_DESC(iobase, "baycom io base address");

MODULE_AUTHOR("Thomas M. Sailer, sailer@ife.ee.ethz.ch, hb9jnx@hb9w.che.eu");
MODULE_DESCRIPTION("Baycom epp amateur radio modem driver");
MODULE_LICENSE("GPL");

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

static void __init baycom_epp_dev_setup(struct net_device *dev)
{
      struct baycom_state *bc = netdev_priv(dev);

      /*
       * initialize part of the baycom_state struct
       */
      bc->dev = dev;
      bc->magic = BAYCOM_MAGIC;
      bc->cfg.fclk = 19666600;
      bc->cfg.bps = 9600;
      /*
       * initialize part of the device struct
       */
      baycom_probe(dev);
}

static int __init init_baycomepp(void)
{
      int i, found = 0;
      char set_hw = 1;

      printk(bc_drvinfo);
      /*
       * register net devices
       */
      for (i = 0; i < NR_PORTS; i++) {
            struct net_device *dev;
            
            dev = alloc_netdev(sizeof(struct baycom_state), "bce%d",
                           baycom_epp_dev_setup);

            if (!dev) {
                  printk(KERN_WARNING "bce%d : out of memory\n", i);
                  return found ? 0 : -ENOMEM;
            }
                  
            sprintf(dev->name, "bce%d", i);
            dev->base_addr = iobase[i];

            if (!mode[i])
                  set_hw = 0;
            if (!set_hw)
                  iobase[i] = 0;

            if (register_netdev(dev)) {
                  printk(KERN_WARNING "%s: cannot register net device %s\n", bc_drvname, dev->name);
                  free_netdev(dev);
                  break;
            }
            if (set_hw && baycom_setmode(netdev_priv(dev), mode[i]))
                  set_hw = 0;
            baycom_device[i] = dev;
            found++;
      }

      return found ? 0 : -ENXIO;
}

static void __exit cleanup_baycomepp(void)
{
      int i;

      for(i = 0; i < NR_PORTS; i++) {
            struct net_device *dev = baycom_device[i];

            if (dev) {
                  struct baycom_state *bc = netdev_priv(dev);
                  if (bc->magic == BAYCOM_MAGIC) {
                        unregister_netdev(dev);
                        free_netdev(dev);
                  } else
                        printk(paranoia_str, "cleanup_module");
            }
      }
}

module_init(init_baycomepp);
module_exit(cleanup_baycomepp);

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

#ifndef MODULE

/*
 * format: baycom_epp=io,mode
 * mode: fpga config options
 */

static int __init baycom_epp_setup(char *str)
{
        static unsigned __initdata nr_dev = 0;
      int ints[2];

        if (nr_dev >= NR_PORTS)
                return 0;
      str = get_options(str, 2, ints);
      if (ints[0] < 1)
            return 0;
      mode[nr_dev] = str;
      iobase[nr_dev] = ints[1];
      nr_dev++;
      return 1;
}

__setup("baycom_epp=", baycom_epp_setup);

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

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