/*
   * Incremental bus scan, based on bus topology

   *
   * Copyright (C) 2004-2006 Kristian Hoegsberg <krh@bitplanet.net>
   *
   * This program is free software; you can redistribute it and/or modify
   * it under the terms of the GNU General Public License as published by
   * the Free Software Foundation; either version 2 of the License, or
   * (at your option) any later version.
   *
   * This program is distributed in the hope that it will be useful,
   * but WITHOUT ANY WARRANTY; without even the implied warranty of
   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   * GNU General Public License for more details.
   *
   * You should have received a copy of the GNU General Public License
   * along with this program; if not, write to the Free Software Foundation,
   * Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
   */

  #include <linux/bug.h>

  #include <linux/errno.h>

  #include <linux/firewire.h>
  #include <linux/firewire-constants.h>

  #include <linux/jiffies.h>
  #include <linux/kernel.h>
  #include <linux/list.h>
  #include <linux/module.h>
  #include <linux/slab.h>
  #include <linux/spinlock.h>

  #include <linux/atomic.h>

  #include <asm/byteorder.h>

  #include <asm/system.h>

  #include "core.h"

  #define SELF_ID_PHY_ID(q)		(((q) >> 24) & 0x3f)
  #define SELF_ID_EXTENDED(q)		(((q) >> 23) & 0x01)
  #define SELF_ID_LINK_ON(q)		(((q) >> 22) & 0x01)
  #define SELF_ID_GAP_COUNT(q)		(((q) >> 16) & 0x3f)
  #define SELF_ID_PHY_SPEED(q)		(((q) >> 14) & 0x03)
  #define SELF_ID_CONTENDER(q)		(((q) >> 11) & 0x01)
  #define SELF_ID_PHY_INITIATOR(q)	(((q) >>  1) & 0x01)
  #define SELF_ID_MORE_PACKETS(q)		(((q) >>  0) & 0x01)

  #define SELF_ID_EXT_SEQUENCE(q)		(((q) >> 20) & 0x07)

  #define SELFID_PORT_CHILD	0x3
  #define SELFID_PORT_PARENT	0x2
  #define SELFID_PORT_NCONN	0x1
  #define SELFID_PORT_NONE	0x0

  static u32 *count_ports(u32 *sid, int *total_port_count, int *child_port_count)
  {
  	u32 q;
  	int port_type, shift, seq;
  
  	*total_port_count = 0;
  	*child_port_count = 0;
  
  	shift = 6;
  	q = *sid;
  	seq = 0;
  
  	while (1) {
  		port_type = (q >> shift) & 0x03;
  		switch (port_type) {
  		case SELFID_PORT_CHILD:
  			(*child_port_count)++;
  		case SELFID_PORT_PARENT:
  		case SELFID_PORT_NCONN:
  			(*total_port_count)++;
  		case SELFID_PORT_NONE:
  			break;
  		}
  
  		shift -= 2;
  		if (shift == 0) {

  			if (!SELF_ID_MORE_PACKETS(q))

  				return sid + 1;
  
  			shift = 16;
  			sid++;
  			q = *sid;

  			/*
  			 * Check that the extra packets actually are

  			 * extended self ID packets and that the
  			 * sequence numbers in the extended self ID

  			 * packets increase as expected.
  			 */

  			if (!SELF_ID_EXTENDED(q) ||
  			    seq != SELF_ID_EXT_SEQUENCE(q))

  				return NULL;
  
  			seq++;
  		}
  	}
  }
  
  static int get_port_type(u32 *sid, int port_index)
  {
  	int index, shift;
  
  	index = (port_index + 5) / 8;
  	shift = 16 - ((port_index + 5) & 7) * 2;
  	return (sid[index] >> shift) & 0x03;
  }

  static struct fw_node *fw_node_create(u32 sid, int port_count, int color)

  {
  	struct fw_node *node;

  	node = kzalloc(sizeof(*node) + port_count * sizeof(node->ports[0]),

  		       GFP_ATOMIC);
  	if (node == NULL)
  		return NULL;
  
  	node->color = color;

  	node->node_id = LOCAL_BUS | SELF_ID_PHY_ID(sid);
  	node->link_on = SELF_ID_LINK_ON(sid);
  	node->phy_speed = SELF_ID_PHY_SPEED(sid);

  	node->initiated_reset = SELF_ID_PHY_INITIATOR(sid);

  	node->port_count = port_count;
  
  	atomic_set(&node->ref_count, 1);
  	INIT_LIST_HEAD(&node->link);
  
  	return node;
  }

  /*
   * Compute the maximum hop count for this node and it's children.  The

   * maximum hop count is the maximum number of connections between any
   * two nodes in the subtree rooted at this node.  We need this for
   * setting the gap count.  As we build the tree bottom up in
   * build_tree() below, this is fairly easy to do: for each node we
   * maintain the max hop count and the max depth, ie the number of hops
   * to the furthest leaf.  Computing the max hop count breaks down into
   * two cases: either the path goes through this node, in which case
   * the hop count is the sum of the two biggest child depths plus 2.
   * Or it could be the case that the max hop path is entirely
   * containted in a child tree, in which case the max hop count is just
   * the max hop count of this child.
   */
  static void update_hop_count(struct fw_node *node)
  {
  	int depths[2] = { -1, -1 };
  	int max_child_hops = 0;
  	int i;
  
  	for (i = 0; i < node->port_count; i++) {

  		if (node->ports[i] == NULL)

  			continue;

  		if (node->ports[i]->max_hops > max_child_hops)
  			max_child_hops = node->ports[i]->max_hops;

  		if (node->ports[i]->max_depth > depths[0]) {

  			depths[1] = depths[0];

  			depths[0] = node->ports[i]->max_depth;
  		} else if (node->ports[i]->max_depth > depths[1])
  			depths[1] = node->ports[i]->max_depth;

  	}
  
  	node->max_depth = depths[0] + 1;
  	node->max_hops = max(max_child_hops, depths[0] + depths[1] + 2);
  }

  static inline struct fw_node *fw_node(struct list_head *l)
  {
  	return list_entry(l, struct fw_node, link);
  }

  /*

   * This function builds the tree representation of the topology given
   * by the self IDs from the latest bus reset.  During the construction
   * of the tree, the function checks that the self IDs are valid and

   * internally consistent.  On success this function returns the

   * fw_node corresponding to the local card otherwise NULL.
   */

  static struct fw_node *build_tree(struct fw_card *card,
  				  u32 *sid, int self_id_count)

  {

  	struct fw_node *node, *child, *local_node, *irm_node;

  	struct list_head stack, *h;

  	u32 *next_sid, *end, q;

  	int i, port_count, child_port_count, phy_id, parent_count, stack_depth;

  	int gap_count;
  	bool beta_repeaters_present;

  
  	local_node = NULL;
  	node = NULL;
  	INIT_LIST_HEAD(&stack);
  	stack_depth = 0;

  	end = sid + self_id_count;

  	phy_id = 0;

  	irm_node = NULL;

  	gap_count = SELF_ID_GAP_COUNT(*sid);

  	beta_repeaters_present = false;

  
  	while (sid < end) {
  		next_sid = count_ports(sid, &port_count, &child_port_count);
  
  		if (next_sid == NULL) {
  			fw_error("Inconsistent extended self IDs.
  ");
  			return NULL;
  		}
  
  		q = *sid;

  		if (phy_id != SELF_ID_PHY_ID(q)) {

  			fw_error("PHY ID mismatch in self ID: %d != %d.
  ",

  				 phy_id, SELF_ID_PHY_ID(q));

  			return NULL;
  		}
  
  		if (child_port_count > stack_depth) {
  			fw_error("Topology stack underflow
  ");
  			return NULL;
  		}

  		/*
  		 * Seek back from the top of our stack to find the
  		 * start of the child nodes for this node.
  		 */

  		for (i = 0, h = &stack; i < child_port_count; i++)
  			h = h->prev;

  		/*
  		 * When the stack is empty, this yields an invalid value,
  		 * but that pointer will never be dereferenced.
  		 */

  		child = fw_node(h);
  
  		node = fw_node_create(q, port_count, card->color);
  		if (node == NULL) {

  			fw_error("Out of memory while building topology.
  ");

  			return NULL;
  		}
  
  		if (phy_id == (card->node_id & 0x3f))
  			local_node = node;

  		if (SELF_ID_CONTENDER(q))

  			irm_node = node;

  
  		parent_count = 0;
  
  		for (i = 0; i < port_count; i++) {
  			switch (get_port_type(sid, i)) {
  			case SELFID_PORT_PARENT:

  				/*
  				 * Who's your daddy?  We dont know the

  				 * parent node at this time, so we
  				 * temporarily abuse node->color for
  				 * remembering the entry in the
  				 * node->ports array where the parent
  				 * node should be.  Later, when we
  				 * handle the parent node, we fix up
  				 * the reference.
  				 */
  				parent_count++;
  				node->color = i;
  				break;
  
  			case SELFID_PORT_CHILD:

  				node->ports[i] = child;

  				/*
  				 * Fix up parent reference for this
  				 * child node.
  				 */

  				child->ports[child->color] = node;

  				child->color = card->color;
  				child = fw_node(child->link.next);
  				break;
  			}
  		}

  		/*
  		 * Check that the node reports exactly one parent

  		 * port, except for the root, which of course should

  		 * have no parents.
  		 */

  		if ((next_sid == end && parent_count != 0) ||
  		    (next_sid < end && parent_count != 1)) {
  			fw_error("Parent port inconsistency for node %d: "
  				 "parent_count=%d
  ", phy_id, parent_count);
  			return NULL;
  		}
  
  		/* Pop the child nodes off the stack and push the new node. */
  		__list_del(h->prev, &stack);
  		list_add_tail(&node->link, &stack);
  		stack_depth += 1 - child_port_count;

  		if (node->phy_speed == SCODE_BETA &&
  		    parent_count + child_port_count > 1)
  			beta_repeaters_present = true;

  		/*

  		 * If PHYs report different gap counts, set an invalid count
  		 * which will force a gap count reconfiguration and a reset.

  		 */

  		if (SELF_ID_GAP_COUNT(q) != gap_count)

  			gap_count = 0;

  
  		update_hop_count(node);

  		sid = next_sid;
  		phy_id++;
  	}
  
  	card->root_node = node;

  	card->irm_node = irm_node;

  	card->gap_count = gap_count;

  	card->beta_repeaters_present = beta_repeaters_present;

  
  	return local_node;
  }

  typedef void (*fw_node_callback_t)(struct fw_card * card,
  				   struct fw_node * node,
  				   struct fw_node * parent);

  static void for_each_fw_node(struct fw_card *card, struct fw_node *root,
  			     fw_node_callback_t callback)

  {
  	struct list_head list;
  	struct fw_node *node, *next, *child, *parent;
  	int i;
  
  	INIT_LIST_HEAD(&list);
  
  	fw_node_get(root);
  	list_add_tail(&root->link, &list);
  	parent = NULL;
  	list_for_each_entry(node, &list, link) {
  		node->color = card->color;
  
  		for (i = 0; i < node->port_count; i++) {

  			child = node->ports[i];

  			if (!child)
  				continue;
  			if (child->color == card->color)
  				parent = child;
  			else {
  				fw_node_get(child);
  				list_add_tail(&child->link, &list);
  			}
  		}
  
  		callback(card, node, parent);
  	}
  
  	list_for_each_entry_safe(node, next, &list, link)
  		fw_node_put(node);
  }

  static void report_lost_node(struct fw_card *card,
  			     struct fw_node *node, struct fw_node *parent)

  {
  	fw_node_event(card, node, FW_NODE_DESTROYED);
  	fw_node_put(node);

  
  	/* Topology has changed - reset bus manager retry counter */
  	card->bm_retries = 0;

  }

  static void report_found_node(struct fw_card *card,
  			      struct fw_node *node, struct fw_node *parent)

  {
  	int b_path = (node->phy_speed == SCODE_BETA);
  
  	if (parent != NULL) {

  		/* min() macro doesn't work here with gcc 3.4 */
  		node->max_speed = parent->max_speed < node->phy_speed ?
  					parent->max_speed : node->phy_speed;

  		node->b_path = parent->b_path && b_path;
  	} else {
  		node->max_speed = node->phy_speed;
  		node->b_path = b_path;
  	}
  
  	fw_node_event(card, node, FW_NODE_CREATED);

  
  	/* Topology has changed - reset bus manager retry counter */
  	card->bm_retries = 0;

  }
  
  void fw_destroy_nodes(struct fw_card *card)
  {
  	unsigned long flags;
  
  	spin_lock_irqsave(&card->lock, flags);
  	card->color++;
  	if (card->local_node != NULL)
  		for_each_fw_node(card, card->local_node, report_lost_node);

  	card->local_node = NULL;

  	spin_unlock_irqrestore(&card->lock, flags);
  }
  
  static void move_tree(struct fw_node *node0, struct fw_node *node1, int port)
  {
  	struct fw_node *tree;
  	int i;

  	tree = node1->ports[port];
  	node0->ports[port] = tree;

  	for (i = 0; i < tree->port_count; i++) {

  		if (tree->ports[i] == node1) {
  			tree->ports[i] = node0;

  			break;
  		}
  	}
  }

  /*
   * Compare the old topology tree for card with the new one specified by root.
   * Queue the nodes and mark them as either found, lost or updated.
   * Update the nodes in the card topology tree as we go.

   */

  static void update_tree(struct fw_card *card, struct fw_node *root)

  {
  	struct list_head list0, list1;

  	struct fw_node *node0, *node1, *next1;

  	int i, event;
  
  	INIT_LIST_HEAD(&list0);
  	list_add_tail(&card->local_node->link, &list0);
  	INIT_LIST_HEAD(&list1);
  	list_add_tail(&root->link, &list1);
  
  	node0 = fw_node(list0.next);
  	node1 = fw_node(list1.next);

  
  	while (&node0->link != &list0) {

  		WARN_ON(node0->port_count != node1->port_count);

  		if (node0->link_on && !node1->link_on)
  			event = FW_NODE_LINK_OFF;
  		else if (!node0->link_on && node1->link_on)
  			event = FW_NODE_LINK_ON;

  		else if (node1->initiated_reset && node1->link_on)
  			event = FW_NODE_INITIATED_RESET;

  		else
  			event = FW_NODE_UPDATED;
  
  		node0->node_id = node1->node_id;
  		node0->color = card->color;
  		node0->link_on = node1->link_on;
  		node0->initiated_reset = node1->initiated_reset;

  		node0->max_hops = node1->max_hops;

  		node1->color = card->color;
  		fw_node_event(card, node0, event);
  
  		if (card->root_node == node1)
  			card->root_node = node0;
  		if (card->irm_node == node1)
  			card->irm_node = node0;
  
  		for (i = 0; i < node0->port_count; i++) {

  			if (node0->ports[i] && node1->ports[i]) {

  				/*
  				 * This port didn't change, queue the

  				 * connected node for further

  				 * investigation.
  				 */

  				if (node0->ports[i]->color == card->color)

  					continue;

  				list_add_tail(&node0->ports[i]->link, &list0);
  				list_add_tail(&node1->ports[i]->link, &list1);
  			} else if (node0->ports[i]) {

  				/*
  				 * The nodes connected here were

  				 * unplugged; unref the lost nodes and
  				 * queue FW_NODE_LOST callbacks for

  				 * them.
  				 */

  				for_each_fw_node(card, node0->ports[i],

  						 report_lost_node);

  				node0->ports[i] = NULL;
  			} else if (node1->ports[i]) {

  				/*
  				 * One or more node were connected to

  				 * this port. Move the new nodes into
  				 * the tree and queue FW_NODE_CREATED

  				 * callbacks for them.
  				 */

  				move_tree(node0, node1, i);

  				for_each_fw_node(card, node0->ports[i],

  						 report_found_node);

  			}
  		}
  
  		node0 = fw_node(node0->link.next);

  		next1 = fw_node(node1->link.next);
  		fw_node_put(node1);
  		node1 = next1;

  	}
  }

  static void update_topology_map(struct fw_card *card,
  				u32 *self_ids, int self_id_count)

  {

  	int node_count = (card->root_node->node_id & 0x3f) + 1;
  	__be32 *map = card->topology_map;
  
  	*map++ = cpu_to_be32((self_id_count + 2) << 16);
  	*map++ = cpu_to_be32(be32_to_cpu(card->topology_map[1]) + 1);
  	*map++ = cpu_to_be32((node_count << 16) | self_id_count);
  
  	while (self_id_count--)
  		*map++ = cpu_to_be32p(self_ids++);

  	fw_compute_block_crc(card->topology_map);

  }

  void fw_core_handle_bus_reset(struct fw_card *card, int node_id, int generation,

  			      int self_id_count, u32 *self_ids, bool bm_abdicate)

  {
  	struct fw_node *local_node;
  	unsigned long flags;

  	/*
  	 * If the selfID buffer is not the immediate successor of the
  	 * previously processed one, we cannot reliably compare the
  	 * old and new topologies.
  	 */

  	if (!is_next_generation(generation, card->generation) &&

  	    card->local_node != NULL) {
  		fw_notify("skipped bus generations, destroying all nodes
  ");
  		fw_destroy_nodes(card);
  		card->bm_retries = 0;
  	}

  	spin_lock_irqsave(&card->lock, flags);

  	card->broadcast_channel_allocated = card->broadcast_channel_auto_allocated;

  	card->node_id = node_id;

  	/*
  	 * Update node_id before generation to prevent anybody from using
  	 * a stale node_id together with a current generation.
  	 */
  	smp_wmb();

  	card->generation = generation;

  	card->reset_jiffies = get_jiffies_64();

  	card->bm_node_id  = 0xffff;

  	card->bm_abdicate = bm_abdicate;

  	fw_schedule_bm_work(card, 0);

  	local_node = build_tree(card, self_ids, self_id_count);
  
  	update_topology_map(card, self_ids, self_id_count);

  
  	card->color++;
  
  	if (local_node == NULL) {
  		fw_error("topology build failed
  ");
  		/* FIXME: We need to issue a bus reset in this case. */
  	} else if (card->local_node == NULL) {
  		card->local_node = local_node;
  		for_each_fw_node(card, local_node, report_found_node);
  	} else {

  		update_tree(card, local_node);

  	}
  
  	spin_unlock_irqrestore(&card->lock, flags);
  }

  EXPORT_SYMBOL(fw_core_handle_bus_reset);