path: root/drivers/net/wan/hdlc_fr.c

/*
 * Generic HDLC support routines for Linux
 * Frame Relay support
 *
 * Copyright (C) 1999 - 2003 Krzysztof Halasa <khc@pm.waw.pl>
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of version 2 of the GNU General Public License
 * as published by the Free Software Foundation.
 *

            Theory of PVC state

 DCE mode:

 (exist,new) -> 0,0 when "PVC create" or if "link unreliable"
         0,x -> 1,1 if "link reliable" when sending FULL STATUS
         1,1 -> 1,0 if received FULL STATUS ACK

 (active)    -> 0 when "ifconfig PVC down" or "link unreliable" or "PVC create"
             -> 1 when "PVC up" and (exist,new) = 1,0

 DTE mode:
 (exist,new,active) = FULL STATUS if "link reliable"
		    = 0, 0, 0 if "link unreliable"
 No LMI:
 active = open and "link reliable"
 exist = new = not used

*/

#include <linux/module.h>
#include <linux/kernel.h>
#include <linux/slab.h>
#include <linux/poll.h>
#include <linux/errno.h>
#include <linux/if_arp.h>
#include <linux/init.h>
#include <linux/skbuff.h>
#include <linux/pkt_sched.h>
#include <linux/random.h>
#include <linux/inetdevice.h>
#include <linux/lapb.h>
#include <linux/rtnetlink.h>
#include <linux/etherdevice.h>
#include <linux/hdlc.h>

#undef DEBUG_PKT
#undef DEBUG_ECN
#undef DEBUG_LINK

#define MAXLEN_LMISTAT  20	/* max size of status enquiry frame */

#define PVC_STATE_NEW	 0x01
#define PVC_STATE_ACTIVE 0x02
#define PVC_STATE_FECN	 0x08 /* FECN condition */
#define PVC_STATE_BECN	 0x10 /* BECN condition */


#define FR_UI		 0x03
#define FR_PAD		 0x00

#define NLPID_IP	 0xCC
#define NLPID_IPV6	 0x8E
#define NLPID_SNAP	 0x80
#define NLPID_PAD	 0x00
#define NLPID_Q933	 0x08


#define LMI_DLCI                   0 /* LMI DLCI */
#define LMI_PROTO               0x08
#define LMI_CALLREF             0x00 /* Call Reference */
#define LMI_ANSI_LOCKSHIFT      0x95 /* ANSI lockshift */
#define LMI_REPTYPE                1 /* report type */
#define LMI_CCITT_REPTYPE       0x51
#define LMI_ALIVE                  3 /* keep alive */
#define LMI_CCITT_ALIVE         0x53
#define LMI_PVCSTAT                7 /* pvc status */
#define LMI_CCITT_PVCSTAT       0x57
#define LMI_FULLREP                0 /* full report  */
#define LMI_INTEGRITY              1 /* link integrity report */
#define LMI_SINGLE                 2 /* single pvc report */
#define LMI_STATUS_ENQUIRY      0x75
#define LMI_STATUS              0x7D /* reply */

#define LMI_REPT_LEN               1 /* report type element length */
#define LMI_INTEG_LEN              2 /* link integrity element length */

#define LMI_LENGTH                13 /* standard LMI frame length */
#define LMI_ANSI_LENGTH           14


typedef struct {
#if defined(__LITTLE_ENDIAN_BITFIELD)
	unsigned ea1:	1;
	unsigned cr:	1;
	unsigned dlcih:	6;
  
	unsigned ea2:	1;
	unsigned de:	1;
	unsigned becn:	1;
	unsigned fecn:	1;
	unsigned dlcil:	4;
#else
	unsigned dlcih:	6;
	unsigned cr:	1;
	unsigned ea1:	1;

	unsigned dlcil:	4;
	unsigned fecn:	1;
	unsigned becn:	1;
	unsigned de:	1;
	unsigned ea2:	1;
#endif
}__attribute__ ((packed)) fr_hdr;


static inline u16 q922_to_dlci(u8 *hdr)
{
	return ((hdr[0] & 0xFC) << 2) | ((hdr[1] & 0xF0) >> 4);
}



static inline void dlci_to_q922(u8 *hdr, u16 dlci)
{
	hdr[0] = (dlci >> 2) & 0xFC;
	hdr[1] = ((dlci << 4) & 0xF0) | 0x01;
}



static inline pvc_device* find_pvc(hdlc_device *hdlc, u16 dlci)
{
	pvc_device *pvc = hdlc->state.fr.first_pvc;

	while (pvc) {
		if (pvc->dlci == dlci)
			return pvc;
		if (pvc->dlci >