baycom_epp.c

linux-2.4.29操作系统的源码

	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;
		ENCODEITERA(0);
		ENCODEITERA(1);
		ENCODEITERA(2);
		ENCODEITERA(3);
		ENCODEITERA(4);
		ENCODEITERA(5);
		ENCODEITERA(6);
		ENCODEITERA(7);
		goto enditer;
		ENCODEITERB(0);
		ENCODEITERB(1);
		ENCODEITERB(2);
		ENCODEITERB(3);
		ENCODEITERB(4);
		ENCODEITERB(5);
		ENCODEITERB(6);
		ENCODEITERB(7);
	enditer:
		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 unsigned short random_seed;

static inline unsigned short random_num(void)
{
	random_seed = 28629 * random_seed + 157;
	return random_seed;
}

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

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 ((random_num() % 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 = (struct baycom_state *)dev->priv;
	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;
	}
	skb->dev = dev;
	cp = skb_put(skb, pktlen);
	*cp++ = 0; /* KISS kludge */
	memcpy(cp, bc->hdlcrx.buf, pktlen - 1);
	skb->protocol = htons(ETH_P_AX25);
	skb->mac.raw = skb->data;
	netif_rx(skb);
	bc->stats.rx_packets++;
}

#define DECODEITERA(j)                                                        \
({                                                                            \
        if (!(notbitstream & (0x0fc << j)))              /* flag or abort */  \
                goto flgabrt##j;                                              \
        if ((bitstream & (0x1f8 << j)) == (0xf8 << j))   /* stuffed bit */    \
                goto stuff##j;                                                \
  enditer##j: ;                                                               \
})

#define DECODEITERB(j)                                                                 \
({                                                                                     \
  flgabrt##j:                                                                          \
        if (!(notbitstream & (0x1fc << j))) {              /* abort received */        \
                state = 0;                                                             \
                goto enditer##j;                                                       \
        }                                                                              \
        if ((bitstream & (0x1fe << j)) != (0x0fc << j))   /* flag received */          \
                goto enditer##j;                                                       \
        if (state)                                                                     \
                do_rxpacket(dev);                                                      \
        bc->hdlcrx.bufcnt = 0;                                                         \
        bc->hdlcrx.bufptr = bc->hdlcrx.buf;                                            \
        state = 1;                                                                     \
        numbits = 7-j;                                                                 \
        goto enditer##j;                                                               \
  stuff##j:                                                                            \
        numbits--;                                                                     \
        bitbuf = (bitbuf & ((~0xff) << j)) | ((bitbuf & ~((~0xff) << j)) << 1);        \
        goto enditer##j;                                                               \
})
        
static int receive(struct net_device *dev, int cnt)
{
	struct baycom_state *bc = (struct baycom_state *)dev->priv;
	struct parport *pp = bc->pdev->port;
        unsigned int bitbuf, notbitstream, bitstream, numbits, state;
	unsigned char tmp[128];
        unsigned char *cp;
	int cnt2, ret = 0;
        
        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;
			DECODEITERA(0);
			DECODEITERA(1);
			DECODEITERA(2);
			DECODEITERA(3);
			DECODEITERA(4);
			DECODEITERA(5);
			DECODEITERA(6);
			DECODEITERA(7);
			goto enddec;
			DECODEITERB(0);
			DECODEITERB(1);
			DECODEITERB(2);
			DECODEITERB(3);
			DECODEITERB(4);
			DECODEITERB(5);
			DECODEITERB(6);
			DECODEITERB(7);
		enddec:
			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__
#define GETTICK(x)                                                \
({                                                                \
	if (cpu_has_tsc)                                          \
		__asm__ __volatile__("rdtsc" : "=a" (x) : : "dx");\
})
#else /* __i386__ */
#define GETTICK(x)
#endif /* __i386__ */

static void epp_bh(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;
	
	baycom_paranoia_check_void(dev, "epp_bh");
	bc = (struct baycom_state *)dev->priv;
	if (!bc->bh_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 */
	queue_task(&bc->run_bh, &tq_timer);
	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;

	baycom_paranoia_check(dev, "baycom_send_packet", 0);
	bc = (struct baycom_state *)dev->priv;
	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;

	baycom_paranoia_check(dev, "baycom_get_stats", NULL);
	bc = (struct baycom_state *)dev->priv;
	/* 
	 * 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;

	baycom_paranoia_check_void(dev, "epp_wakeup");
        bc = (struct baycom_state *)dev->priv;
        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)