root/drivers/net/hamradio/baycom_epp.c
// 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");
                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");
                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,
};

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