core-topology.c

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/*
 * Incremental bus scan, based on bus topology
 *
 * Copyright (C) 2004-2006 Kristian Hoegsberg <[email protected]>
 *
 * 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 "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_err(card, "inconsistent extended self IDs\n");
            return NULL;
        }

        q = *sid;
        if (phy_id != SELF_ID_PHY_ID(q)) {
            fw_err(card, "PHY ID mismatch in self ID: %d != %d\n",
                   phy_id, SELF_ID_PHY_ID(q));
            return NULL;
        }

        if (child_port_count > stack_depth) {
            fw_err(card, "topology stack underflow\n");
            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_err(card, "out of memory while building topology\n");
            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_err(card, "parent port inconsistency for node %d: "
                   "parent_count=%d\n", 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_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_err(card, "topology build failed\n");
        /* 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);