// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * Incremental bus scan, based on bus topology
 *
 * Copyright (C) 2004-2006 Kristian Hoegsberg <krh@bitplanet.net>
 */

#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"
#include "phy-packet-definitions.h"
#include <trace/events/firewire.h>

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

        node = kzalloc_flex(*node, ports, port_count, GFP_ATOMIC);
        if (node == NULL)
                return NULL;

        node->color = color;
        node->node_id = LOCAL_BUS | phy_packet_self_id_get_phy_id(sid);
        node->link_on = phy_packet_self_id_zero_get_link_active(sid);
        // NOTE: Only two bits, thus only for SCODE_100, SCODE_200, SCODE_400, and SCODE_BETA.
        node->phy_speed = phy_packet_self_id_zero_get_scode(sid);
        node->initiated_reset = phy_packet_self_id_zero_get_initiated_reset(sid);
        node->port_count = port_count;

        kref_init(&node->kref);
        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
 * contained 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, const u32 *sid, int self_id_count,
                                  unsigned int generation)
{
        struct self_id_sequence_enumerator enumerator = {
                .cursor = sid,
                .quadlet_count = self_id_count,
        };
        struct fw_node *node, *child, *local_node, *irm_node;
        struct list_head stack;
        int phy_id, stack_depth;
        int gap_count;
        bool beta_repeaters_present;

        local_node = NULL;
        node = NULL;
        INIT_LIST_HEAD(&stack);
        stack_depth = 0;
        phy_id = 0;
        irm_node = NULL;
        gap_count = phy_packet_self_id_zero_get_gap_count(*sid);
        beta_repeaters_present = false;

        while (enumerator.quadlet_count > 0) {
                unsigned int child_port_count = 0;
                unsigned int total_port_count = 0;
                unsigned int parent_count = 0;
                unsigned int quadlet_count;
                const u32 *self_id_sequence;
                unsigned int port_capacity;
                enum phy_packet_self_id_port_status port_status;
                unsigned int port_index;
                struct list_head *h;
                int i;

                self_id_sequence = self_id_sequence_enumerator_next(&enumerator, &quadlet_count);
                if (IS_ERR(self_id_sequence)) {
                        if (PTR_ERR(self_id_sequence) != -ENODATA) {
                                fw_err(card, "inconsistent extended self IDs: %ld\n",
                                       PTR_ERR(self_id_sequence));
                                return NULL;
                        }
                        break;
                }

                port_capacity = self_id_sequence_get_port_capacity(quadlet_count);
                trace_self_id_sequence(card->index, self_id_sequence, quadlet_count, generation);

                for (port_index = 0; port_index < port_capacity; ++port_index) {
                        port_status = self_id_sequence_get_port_status(self_id_sequence, quadlet_count,
                                                                       port_index);
                        switch (port_status) {
                        case PHY_PACKET_SELF_ID_PORT_STATUS_CHILD:
                                ++child_port_count;
                                fallthrough;
                        case PHY_PACKET_SELF_ID_PORT_STATUS_PARENT:
                        case PHY_PACKET_SELF_ID_PORT_STATUS_NCONN:
                                ++total_port_count;
                                fallthrough;
                        case PHY_PACKET_SELF_ID_PORT_STATUS_NONE:
                        default:
                                break;
                        }
                }

                if (phy_id != phy_packet_self_id_get_phy_id(self_id_sequence[0])) {
                        fw_err(card, "PHY ID mismatch in self ID: %d != %d\n",
                               phy_id, phy_packet_self_id_get_phy_id(self_id_sequence[0]));
                        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(self_id_sequence[0], total_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 (phy_packet_self_id_zero_get_contender(self_id_sequence[0]))
                        irm_node = node;

                for (port_index = 0; port_index < total_port_count; ++port_index) {
                        port_status = self_id_sequence_get_port_status(self_id_sequence, quadlet_count,
                                                                       port_index);
                        switch (port_status) {
                        case PHY_PACKET_SELF_ID_PORT_STATUS_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 = port_index;
                                break;

                        case PHY_PACKET_SELF_ID_PORT_STATUS_CHILD:
                                node->ports[port_index] = 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;
                        case PHY_PACKET_SELF_ID_PORT_STATUS_NCONN:
                        case PHY_PACKET_SELF_ID_PORT_STATUS_NONE:
                        default:
                                break;
                        }
                }

                // Check that the node reports exactly one parent port, except for the root, which
                // of course should have no parents.
                if ((enumerator.quadlet_count == 0 && parent_count != 0) ||
                    (enumerator.quadlet_count > 0 && 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 (phy_packet_self_id_zero_get_gap_count(self_id_sequence[0]) != gap_count)
                        gap_count = GAP_COUNT_MISMATCHED;

                update_hop_count(node);

                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)
__must_hold(&card->lock)
{
        lockdep_assert_held(&card->lock);

        card->color++;
        if (card->local_node != NULL)
                for_each_fw_node(card, card->local_node, report_lost_node);
        card->local_node = NULL;
}

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(__be32 *buffer, size_t buffer_size, int root_node_id,
                                const u32 *self_ids, int self_id_count)
{
        __be32 *map = buffer;
        u32 next_generation = be32_to_cpu(buffer[1]) + 1;
        int node_count = (root_node_id & 0x3f) + 1;

        memset(map, 0, buffer_size);

        *map++ = cpu_to_be32((self_id_count + 2) << 16);
        *map++ = cpu_to_be32(next_generation);
        *map++ = cpu_to_be32((node_count << 16) | self_id_count);

        while (self_id_count--)
                *map++ = cpu_to_be32p(self_ids++);

        fw_compute_block_crc(buffer);
}

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;

        trace_bus_reset_handle(card->index, generation, node_id, bm_abdicate, self_ids, self_id_count);

        scoped_guard(spinlock, &card->lock) {
                // 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;
                }
                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;

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

                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);
                }
        }

        fw_schedule_bm_work(card, 0);

        // Just used by transaction layer.
        scoped_guard(spinlock, &card->topology_map.lock) {
                update_topology_map(card->topology_map.buffer, sizeof(card->topology_map.buffer),
                                    card->root_node->node_id, self_ids, self_id_count);
        }
}
EXPORT_SYMBOL(fw_core_handle_bus_reset);