/*
   * net/tipc/link.h: Include file for TIPC link code
   *
   * Copyright (c) 1995-2006, Ericsson AB
   * Copyright (c) 2004-2005, 2010-2011, Wind River Systems
   * All rights reserved.
   *
   * Redistribution and use in source and binary forms, with or without
   * modification, are permitted provided that the following conditions are met:
   *
   * 1. Redistributions of source code must retain the above copyright
   *    notice, this list of conditions and the following disclaimer.
   * 2. Redistributions in binary form must reproduce the above copyright
   *    notice, this list of conditions and the following disclaimer in the
   *    documentation and/or other materials provided with the distribution.
   * 3. Neither the names of the copyright holders nor the names of its
   *    contributors may be used to endorse or promote products derived from
   *    this software without specific prior written permission.
   *
   * Alternatively, this software may be distributed under the terms of the
   * GNU General Public License ("GPL") version 2 as published by the Free
   * Software Foundation.
   *
   * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
   * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
   * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
   * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
   * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
   * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
   * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
   * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
   * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
   * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
   * POSSIBILITY OF SUCH DAMAGE.
   */
  
  #ifndef _TIPC_LINK_H
  #define _TIPC_LINK_H
  
  #include "msg.h"
  #include "node.h"
  
  /*
   * Link reassembly status codes
   */
  #define LINK_REASM_ERROR	-1
  #define LINK_REASM_COMPLETE	1
  
  /*
   * Out-of-range value for link sequence numbers
   */
  #define INVALID_LINK_SEQ 0x10000
  
  /*
   * Link states
   */
  #define WORKING_WORKING 560810u
  #define WORKING_UNKNOWN 560811u
  #define RESET_UNKNOWN   560812u
  #define RESET_RESET     560813u
  
  /*
   * Starting value for maximum packet size negotiation on unicast links
   * (unless bearer MTU is less)
   */
  #define MAX_PKT_DEFAULT 1500
  
  struct tipc_stats {
  	u32 sent_info;		/* used in counting # sent packets */
  	u32 recv_info;		/* used in counting # recv'd packets */
  	u32 sent_states;
  	u32 recv_states;
  	u32 sent_probes;
  	u32 recv_probes;
  	u32 sent_nacks;
  	u32 recv_nacks;
  	u32 sent_acks;
  	u32 sent_bundled;
  	u32 sent_bundles;
  	u32 recv_bundled;
  	u32 recv_bundles;
  	u32 retransmitted;
  	u32 sent_fragmented;
  	u32 sent_fragments;
  	u32 recv_fragmented;
  	u32 recv_fragments;
  	u32 link_congs;		/* # port sends blocked by congestion */
  	u32 deferred_recv;
  	u32 duplicates;
  	u32 max_queue_sz;	/* send queue size high water mark */
  	u32 accu_queue_sz;	/* used for send queue size profiling */
  	u32 queue_sz_counts;	/* used for send queue size profiling */
  	u32 msg_length_counts;	/* used for message length profiling */
  	u32 msg_lengths_total;	/* used for message length profiling */
  	u32 msg_length_profile[7]; /* used for msg. length profiling */
  };
  
  /**
   * struct tipc_link - TIPC link data structure
   * @addr: network address of link's peer node
   * @name: link name character string
   * @media_addr: media address to use when sending messages over link
   * @timer: link timer
   * @owner: pointer to peer node
   * @link_list: adjacent links in bearer's list of links
   * @started: indicates if link has been started
   * @checkpoint: reference point for triggering link continuity checking
   * @peer_session: link session # being used by peer end of link
   * @peer_bearer_id: bearer id used by link's peer endpoint
   * @b_ptr: pointer to bearer used by link
   * @tolerance: minimum link continuity loss needed to reset link [in ms]
   * @continuity_interval: link continuity testing interval [in ms]
   * @abort_limit: # of unacknowledged continuity probes needed to reset link
   * @state: current state of link FSM
   * @fsm_msg_cnt: # of protocol messages link FSM has sent in current state
   * @proto_msg: template for control messages generated by link
   * @pmsg: convenience pointer to "proto_msg" field
   * @priority: current link priority
   * @queue_limit: outbound message queue congestion thresholds (indexed by user)
   * @exp_msg_count: # of tunnelled messages expected during link changeover
   * @reset_checkpoint: seq # of last acknowledged message at time of link reset
   * @max_pkt: current maximum packet size for this link
   * @max_pkt_target: desired maximum packet size for this link
   * @max_pkt_probes: # of probes based on current (max_pkt, max_pkt_target)
   * @out_queue_size: # of messages in outbound message queue
   * @first_out: ptr to first outbound message in queue
   * @last_out: ptr to last outbound message in queue
   * @next_out_no: next sequence number to use for outbound messages
   * @last_retransmitted: sequence number of most recently retransmitted message
   * @stale_count: # of identical retransmit requests made by peer
   * @next_in_no: next sequence number to expect for inbound messages
   * @deferred_inqueue_sz: # of messages in inbound message queue
   * @oldest_deferred_in: ptr to first inbound message in queue
   * @newest_deferred_in: ptr to last inbound message in queue
   * @unacked_window: # of inbound messages rx'd without ack'ing back to peer
   * @proto_msg_queue: ptr to (single) outbound control message
   * @retransm_queue_size: number of messages to retransmit
   * @retransm_queue_head: sequence number of first message to retransmit
   * @next_out: ptr to first unsent outbound message in queue
   * @waiting_ports: linked list of ports waiting for link congestion to abate
   * @long_msg_seq_no: next identifier to use for outbound fragmented messages
   * @reasm_head: list head of partially reassembled inbound message fragments
   * @reasm_tail: last fragment received
   * @stats: collects statistics regarding link activity
   */
  struct tipc_link {
  	u32 addr;
  	char name[TIPC_MAX_LINK_NAME];
  	struct tipc_media_addr media_addr;
  	struct timer_list timer;
  	struct tipc_node *owner;
  	struct list_head link_list;
  
  	/* Management and link supervision data */
  	int started;
  	u32 checkpoint;
  	u32 peer_session;
  	u32 peer_bearer_id;
  	struct tipc_bearer *b_ptr;
  	u32 tolerance;
  	u32 continuity_interval;
  	u32 abort_limit;
  	int state;
  	u32 fsm_msg_cnt;
  	struct {
  		unchar hdr[INT_H_SIZE];
  		unchar body[TIPC_MAX_IF_NAME];
  	} proto_msg;
  	struct tipc_msg *pmsg;
  	u32 priority;
  	u32 queue_limit[15];	/* queue_limit[0]==window limit */
  
  	/* Changeover */
  	u32 exp_msg_count;
  	u32 reset_checkpoint;
  
  	/* Max packet negotiation */
  	u32 max_pkt;
  	u32 max_pkt_target;
  	u32 max_pkt_probes;
  
  	/* Sending */
  	u32 out_queue_size;
  	struct sk_buff *first_out;
  	struct sk_buff *last_out;
  	u32 next_out_no;
  	u32 last_retransmitted;
  	u32 stale_count;
  
  	/* Reception */
  	u32 next_in_no;
  	u32 deferred_inqueue_sz;
  	struct sk_buff *oldest_deferred_in;
  	struct sk_buff *newest_deferred_in;
  	u32 unacked_window;
  
  	/* Congestion handling */
  	struct sk_buff *proto_msg_queue;
  	u32 retransm_queue_size;
  	u32 retransm_queue_head;
  	struct sk_buff *next_out;
  	struct list_head waiting_ports;
  
  	/* Fragmentation/reassembly */
  	u32 long_msg_seq_no;
  	struct sk_buff *reasm_head;
  	struct sk_buff *reasm_tail;
  
  	/* Statistics */
  	struct tipc_stats stats;
  };
  
  struct tipc_port;
  
  struct tipc_link *tipc_link_create(struct tipc_node *n_ptr,
  			      struct tipc_bearer *b_ptr,
  			      const struct tipc_media_addr *media_addr);
  void tipc_link_delete(struct tipc_link *l_ptr);
  void tipc_link_failover_send_queue(struct tipc_link *l_ptr);
  void tipc_link_dup_send_queue(struct tipc_link *l_ptr,
  			      struct tipc_link *dest);
  void tipc_link_reset_fragments(struct tipc_link *l_ptr);
  int tipc_link_is_up(struct tipc_link *l_ptr);
  int tipc_link_is_active(struct tipc_link *l_ptr);
  void tipc_link_purge_queues(struct tipc_link *l_ptr);
  struct sk_buff *tipc_link_cmd_config(const void *req_tlv_area,
  				     int req_tlv_space,
  				     u16 cmd);
  struct sk_buff *tipc_link_cmd_show_stats(const void *req_tlv_area,
  					 int req_tlv_space);
  struct sk_buff *tipc_link_cmd_reset_stats(const void *req_tlv_area,
  					  int req_tlv_space);
  void tipc_link_reset(struct tipc_link *l_ptr);
  int tipc_link_send(struct sk_buff *buf, u32 dest, u32 selector);
  void tipc_link_send_names(struct list_head *message_list, u32 dest);
  int tipc_link_send_buf(struct tipc_link *l_ptr, struct sk_buff *buf);
  u32 tipc_link_get_max_pkt(u32 dest, u32 selector);
  int tipc_link_send_sections_fast(struct tipc_port *sender,
  				 struct iovec const *msg_sect,
  				 unsigned int len, u32 destnode);
  void tipc_link_recv_bundle(struct sk_buff *buf);
  int  tipc_link_recv_fragment(struct sk_buff **reasm_head,
  			     struct sk_buff **reasm_tail,
  			     struct sk_buff **fbuf);
  void tipc_link_send_proto_msg(struct tipc_link *l_ptr, u32 msg_typ, int prob,
  			      u32 gap, u32 tolerance, u32 priority,
  			      u32 acked_mtu);
  void tipc_link_push_queue(struct tipc_link *l_ptr);
  u32 tipc_link_defer_pkt(struct sk_buff **head, struct sk_buff **tail,
  		   struct sk_buff *buf);
  void tipc_link_wakeup_ports(struct tipc_link *l_ptr, int all);
  void tipc_link_set_queue_limits(struct tipc_link *l_ptr, u32 window);
  void tipc_link_retransmit(struct tipc_link *l_ptr,
  			  struct sk_buff *start, u32 retransmits);
  
  /*
   * Link sequence number manipulation routines (uses modulo 2**16 arithmetic)
   */
  static inline u32 buf_seqno(struct sk_buff *buf)
  {
  	return msg_seqno(buf_msg(buf));
  }
  
  static inline u32 mod(u32 x)
  {
  	return x & 0xffffu;
  }
  
  static inline int between(u32 lower, u32 upper, u32 n)
  {
  	if ((lower < n) && (n < upper))
  		return 1;
  	if ((upper < lower) && ((n > lower) || (n < upper)))
  		return 1;
  	return 0;
  }
  
  static inline int less_eq(u32 left, u32 right)
  {
  	return mod(right - left) < 32768u;
  }
  
  static inline int less(u32 left, u32 right)
  {
  	return less_eq(left, right) && (mod(right) != mod(left));
  }
  
  static inline u32 lesser(u32 left, u32 right)
  {
  	return less_eq(left, right) ? left : right;
  }
  
  
  /*
   * Link status checking routines
   */
  static inline int link_working_working(struct tipc_link *l_ptr)
  {
  	return l_ptr->state == WORKING_WORKING;
  }
  
  static inline int link_working_unknown(struct tipc_link *l_ptr)
  {
  	return l_ptr->state == WORKING_UNKNOWN;
  }
  
  static inline int link_reset_unknown(struct tipc_link *l_ptr)
  {
  	return l_ptr->state == RESET_UNKNOWN;
  }
  
  static inline int link_reset_reset(struct tipc_link *l_ptr)
  {
  	return l_ptr->state == RESET_RESET;
  }
  
  static inline int link_congested(struct tipc_link *l_ptr)
  {
  	return l_ptr->out_queue_size >= l_ptr->queue_limit[0];
  }
  
  #endif