// SPDX-License-Identifier: GPL-2.0-or-later
/*****************************************************************************/

/*
 *	baycom_epp.c  -- baycom epp radio modem driver.
 *
 *	Copyright (C) 1998-2000
 *          Thomas Sailer (sailer@ife.ee.ethz.ch)
 *
 *  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/sched.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 <linux/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"
"baycom_epp: version 0.7\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;

	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 const eppconfig_path[] = "/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[] = {
		(char *)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->dev->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 (get_random_u8() > 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;
			}
			fallthrough;

		default:
			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);
		dev->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->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;

					/* 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;
}

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

#define GETTICK(x)						\
({								\
	x = (unsigned int)get_cycles();				\
})

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

	if (skb->protocol == htons(ETH_P_IP))
		return ax25_ip_xmit(skb);

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

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

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 */
	dev_addr_set(dev, sa->sa_data);
	return 0;                                         
}

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

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;
	struct pardev_cb par_cb;
	
        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));
	memset(&par_cb, 0, sizeof(par_cb));
	par_cb.wakeup = epp_wakeup;
	par_cb.private = (void *)dev;
	par_cb.flags = PARPORT_DEV_EXCL;
	for (i = 0; i < NR_PORTS; i++)
		if (baycom_device[i] == dev)
			break;

	if (i == NR_PORTS) {
		pr_err("%s: no device found\n", bc_drvname);
		parport_put_port(pp);
		return -ENODEV;
	}

	bc->pdev = parport_register_dev_model(pp, dev->name, &par_cb, i);
	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;
	cancel_delayed_work_sync(&bc->run_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);
	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,"loopback"))
		bc->cfg.loopback = 1;
	if (strstr(modestr, "noloopback"))
		bc->cfg.loopback = 0;
	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_siocdevprivate(struct net_device *dev, struct ifreq *ifr,
				 void __user *data, int cmd)
{
	struct baycom_state *bc = netdev_priv(dev);
	struct hdlcdrv_ioctl hi;

	if (cmd != SIOCDEVPRIVATE)
		return -ENOIOCTLCMD;

	if (copy_from_user(&hi, 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 = dev->stats.tx_packets;
		hi.data.cs.tx_errors = dev->stats.tx_errors;
		hi.data.cs.rx_packets = dev->stats.rx_packets;
		hi.data.cs.rx_errors = dev->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:
		strscpy_pad(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:
		strscpy_pad(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(data, &hi, sizeof(hi)))
		return -EFAULT;
	return 0;
}

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

static const struct net_device_ops baycom_netdev_ops = {
	.ndo_open	     = epp_open,
	.ndo_stop	     = epp_close,
	.ndo_siocdevprivate  = baycom_siocdevprivate,
	.ndo_start_xmit      = baycom_send_packet,
	.ndo_set_mac_address = baycom_set_mac_address,
};

/*
 * 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
	 */

	/* Fill in the fields of the device structure */
	bc->skb = NULL;
	
	dev->netdev_ops = &baycom_netdev_ops;
	dev->header_ops = &ax25_header_ops;
	
	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);
	dev_addr_set(dev, (u8 *)&null_ax25_address);
	dev->tx_queue_len = 16;

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

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

/*
 * command line settable parameters
 */
static 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_hw_array(iobase, int, ioport, 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 int baycom_epp_par_probe(struct pardevice *par_dev)
{
	struct device_driver *drv = par_dev->dev.driver;
	int len = strlen(drv->name);

	if (strncmp(par_dev->name, drv->name, len))
		return -ENODEV;

	return 0;
}

static struct parport_driver baycom_epp_par_driver = {
	.name = "bce",
	.probe = baycom_epp_par_probe,
	.devmodel = true,
};

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, ret;
	char set_hw = 1;

	printk(bc_drvinfo);

	ret = parport_register_driver(&baycom_epp_par_driver);
	if (ret)
		return ret;

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

	if (found == 0) {
		parport_unregister_driver(&baycom_epp_par_driver);
		return -ENXIO;
	}

	return 0;
}

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");
		}
	}
	parport_unregister_driver(&baycom_epp_par_driver);
}

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