drivers/firewire/core-topology.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * Incremental bus scan, based on bus topology
   4  *
   5  * Copyright (C) 2004-2006 Kristian Hoegsberg <krh@bitplanet.net>
   6  */
   7
   8 #include <linux/bug.h>
   9 #include <linux/errno.h>
  10 #include <linux/firewire.h>
  11 #include <linux/firewire-constants.h>
  12 #include <linux/jiffies.h>
  13 #include <linux/kernel.h>
  14 #include <linux/list.h>
  15 #include <linux/module.h>
  16 #include <linux/slab.h>
  17 #include <linux/spinlock.h>
  18
  19 #include <linux/atomic.h>
  20 #include <asm/byteorder.h>
  21
  22 #include "core.h"
  23
  24 #define SELF_ID_PHY_ID(q)               (((q) >> 24) & 0x3f)
  25 #define SELF_ID_EXTENDED(q)             (((q) >> 23) & 0x01)
  26 #define SELF_ID_LINK_ON(q)              (((q) >> 22) & 0x01)
  27 #define SELF_ID_GAP_COUNT(q)            (((q) >> 16) & 0x3f)
  28 #define SELF_ID_PHY_SPEED(q)            (((q) >> 14) & 0x03)
  29 #define SELF_ID_CONTENDER(q)            (((q) >> 11) & 0x01)
  30 #define SELF_ID_PHY_INITIATOR(q)        (((q) >>  1) & 0x01)
  31 #define SELF_ID_MORE_PACKETS(q)         (((q) >>  0) & 0x01)
  32
  33 #define SELF_ID_EXT_SEQUENCE(q)         (((q) >> 20) & 0x07)
  34
  35 #define SELFID_PORT_CHILD       0x3
  36 #define SELFID_PORT_PARENT      0x2
  37 #define SELFID_PORT_NCONN       0x1
  38 #define SELFID_PORT_NONE        0x0
  39
  40 static u32 *count_ports(u32 *sid, int *total_port_count, int *child_port_count)
  41 {
  42         u32 q;
  43         int port_type, shift, seq;
  44
  45         *total_port_count = 0;
  46         *child_port_count = 0;
  47
  48         shift = 6;
  49         q = *sid;
  50         seq = 0;
  51
  52         while (1) {
  53                 port_type = (q >> shift) & 0x03;
  54                 switch (port_type) {
  55                 case SELFID_PORT_CHILD:
  56                         (*child_port_count)++;
  57                         fallthrough;
  58                 case SELFID_PORT_PARENT:
  59                 case SELFID_PORT_NCONN:
  60                         (*total_port_count)++;
  61                         fallthrough;
  62                 case SELFID_PORT_NONE:
  63                         break;
  64                 }
  65
  66                 shift -= 2;
  67                 if (shift == 0) {
  68                         if (!SELF_ID_MORE_PACKETS(q))
  69                                 return sid + 1;
  70
  71                         shift = 16;
  72                         sid++;
  73                         q = *sid;
  74
  75                         /*
  76                          * Check that the extra packets actually are
  77                          * extended self ID packets and that the
  78                          * sequence numbers in the extended self ID
  79                          * packets increase as expected.
  80                          */
  81
  82                         if (!SELF_ID_EXTENDED(q) ||
  83                             seq != SELF_ID_EXT_SEQUENCE(q))
  84                                 return NULL;
  85
  86                         seq++;
  87                 }
  88         }
  89 }
  90
  91 static int get_port_type(u32 *sid, int port_index)
  92 {
  93         int index, shift;
  94
  95         index = (port_index + 5) / 8;
  96         shift = 16 - ((port_index + 5) & 7) * 2;
  97         return (sid[index] >> shift) & 0x03;
  98 }
  99
 100 static struct fw_node *fw_node_create(u32 sid, int port_count, int color)
 101 {
 102         struct fw_node *node;
 103
 104         node = kzalloc(struct_size(node, ports, port_count), GFP_ATOMIC);
 105         if (node == NULL)
 106                 return NULL;
 107
 108         node->color = color;
 109         node->node_id = LOCAL_BUS | SELF_ID_PHY_ID(sid);
 110         node->link_on = SELF_ID_LINK_ON(sid);
 111         node->phy_speed = SELF_ID_PHY_SPEED(sid);
 112         node->initiated_reset = SELF_ID_PHY_INITIATOR(sid);
 113         node->port_count = port_count;
 114
 115         refcount_set(&node->ref_count, 1);
 116         INIT_LIST_HEAD(&node->link);
 117
 118         return node;
 119 }
 120
 121 /*
 122  * Compute the maximum hop count for this node and it's children.  The
 123  * maximum hop count is the maximum number of connections between any
 124  * two nodes in the subtree rooted at this node.  We need this for
 125  * setting the gap count.  As we build the tree bottom up in
 126  * build_tree() below, this is fairly easy to do: for each node we
 127  * maintain the max hop count and the max depth, ie the number of hops
 128  * to the furthest leaf.  Computing the max hop count breaks down into
 129  * two cases: either the path goes through this node, in which case
 130  * the hop count is the sum of the two biggest child depths plus 2.
 131  * Or it could be the case that the max hop path is entirely
 132  * containted in a child tree, in which case the max hop count is just
 133  * the max hop count of this child.
 134  */
 135 static void update_hop_count(struct fw_node *node)
 136 {
 137         int depths[2] = { -1, -1 };
 138         int max_child_hops = 0;
 139         int i;
 140
 141         for (i = 0; i < node->port_count; i++) {
 142                 if (node->ports[i] == NULL)
 143                         continue;
 144
 145                 if (node->ports[i]->max_hops > max_child_hops)
 146                         max_child_hops = node->ports[i]->max_hops;
 147
 148                 if (node->ports[i]->max_depth > depths[0]) {
 149                         depths[1] = depths[0];
 150                         depths[0] = node->ports[i]->max_depth;
 151                 } else if (node->ports[i]->max_depth > depths[1])
 152                         depths[1] = node->ports[i]->max_depth;
 153         }
 154
 155         node->max_depth = depths[0] + 1;
 156         node->max_hops = max(max_child_hops, depths[0] + depths[1] + 2);
 157 }
 158
 159 static inline struct fw_node *fw_node(struct list_head *l)
 160 {
 161         return list_entry(l, struct fw_node, link);
 162 }
 163
 164 /*
 165  * This function builds the tree representation of the topology given
 166  * by the self IDs from the latest bus reset.  During the construction
 167  * of the tree, the function checks that the self IDs are valid and
 168  * internally consistent.  On success this function returns the
 169  * fw_node corresponding to the local card otherwise NULL.
 170  */
 171 static struct fw_node *build_tree(struct fw_card *card,
 172                                   u32 *sid, int self_id_count)
 173 {
 174         struct fw_node *node, *child, *local_node, *irm_node;
 175         struct list_head stack, *h;
 176         u32 *next_sid, *end, q;
 177         int i, port_count, child_port_count, phy_id, parent_count, stack_depth;
 178         int gap_count;
 179         bool beta_repeaters_present;
 180
 181         local_node = NULL;
 182         node = NULL;
 183         INIT_LIST_HEAD(&stack);
 184         stack_depth = 0;
 185         end = sid + self_id_count;
 186         phy_id = 0;
 187         irm_node = NULL;
 188         gap_count = SELF_ID_GAP_COUNT(*sid);
 189         beta_repeaters_present = false;
 190
 191         while (sid < end) {
 192                 next_sid = count_ports(sid, &port_count, &child_port_count);
 193
 194                 if (next_sid == NULL) {
 195                         fw_err(card, "inconsistent extended self IDs\n");
 196                         return NULL;
 197                 }
 198
 199                 q = *sid;
 200                 if (phy_id != SELF_ID_PHY_ID(q)) {
 201                         fw_err(card, "PHY ID mismatch in self ID: %d != %d\n",
 202                                phy_id, SELF_ID_PHY_ID(q));
 203                         return NULL;
 204                 }
 205
 206                 if (child_port_count > stack_depth) {
 207                         fw_err(card, "topology stack underflow\n");
 208                         return NULL;
 209                 }
 210
 211                 /*
 212                  * Seek back from the top of our stack to find the
 213                  * start of the child nodes for this node.
 214                  */
 215                 for (i = 0, h = &stack; i < child_port_count; i++)
 216                         h = h->prev;
 217                 /*
 218                  * When the stack is empty, this yields an invalid value,
 219                  * but that pointer will never be dereferenced.
 220                  */
 221                 child = fw_node(h);
 222
 223                 node = fw_node_create(q, port_count, card->color);
 224                 if (node == NULL) {
 225                         fw_err(card, "out of memory while building topology\n");
 226                         return NULL;
 227                 }
 228
 229                 if (phy_id == (card->node_id & 0x3f))
 230                         local_node = node;
 231
 232                 if (SELF_ID_CONTENDER(q))
 233                         irm_node = node;
 234
 235                 parent_count = 0;
 236
 237                 for (i = 0; i < port_count; i++) {
 238                         switch (get_port_type(sid, i)) {
 239                         case SELFID_PORT_PARENT:
 240                                 /*
 241                                  * Who's your daddy?  We dont know the
 242                                  * parent node at this time, so we
 243                                  * temporarily abuse node->color for
 244                                  * remembering the entry in the
 245                                  * node->ports array where the parent
 246                                  * node should be.  Later, when we
 247                                  * handle the parent node, we fix up
 248                                  * the reference.
 249                                  */
 250                                 parent_count++;
 251                                 node->color = i;
 252                                 break;
 253
 254                         case SELFID_PORT_CHILD:
 255                                 node->ports[i] = child;
 256                                 /*
 257                                  * Fix up parent reference for this
 258                                  * child node.
 259                                  */
 260                                 child->ports[child->color] = node;
 261                                 child->color = card->color;
 262                                 child = fw_node(child->link.next);
 263                                 break;
 264                         }
 265                 }
 266
 267                 /*
 268                  * Check that the node reports exactly one parent
 269                  * port, except for the root, which of course should
 270                  * have no parents.
 271                  */
 272                 if ((next_sid == end && parent_count != 0) ||
 273                     (next_sid < end && parent_count != 1)) {
 274                         fw_err(card, "parent port inconsistency for node %d: "
 275                                "parent_count=%d\n", phy_id, parent_count);
 276                         return NULL;
 277                 }
 278
 279                 /* Pop the child nodes off the stack and push the new node. */
 280                 __list_del(h->prev, &stack);
 281                 list_add_tail(&node->link, &stack);
 282                 stack_depth += 1 - child_port_count;
 283
 284                 if (node->phy_speed == SCODE_BETA &&
 285                     parent_count + child_port_count > 1)
 286                         beta_repeaters_present = true;
 287
 288                 /*
 289                  * If PHYs report different gap counts, set an invalid count
 290                  * which will force a gap count reconfiguration and a reset.
 291                  */
 292                 if (SELF_ID_GAP_COUNT(q) != gap_count)
 293                         gap_count = 0;
 294
 295                 update_hop_count(node);
 296
 297                 sid = next_sid;
 298                 phy_id++;
 299         }
 300
 301         card->root_node = node;
 302         card->irm_node = irm_node;
 303         card->gap_count = gap_count;
 304         card->beta_repeaters_present = beta_repeaters_present;
 305
 306         return local_node;
 307 }
 308
 309 typedef void (*fw_node_callback_t)(struct fw_card * card,
 310                                    struct fw_node * node,
 311                                    struct fw_node * parent);
 312
 313 static void for_each_fw_node(struct fw_card *card, struct fw_node *root,
 314                              fw_node_callback_t callback)
 315 {
 316         struct list_head list;
 317         struct fw_node *node, *next, *child, *parent;
 318         int i;
 319
 320         INIT_LIST_HEAD(&list);
 321
 322         fw_node_get(root);
 323         list_add_tail(&root->link, &list);
 324         parent = NULL;
 325         list_for_each_entry(node, &list, link) {
 326                 node->color = card->color;
 327
 328                 for (i = 0; i < node->port_count; i++) {
 329                         child = node->ports[i];
 330                         if (!child)
 331                                 continue;
 332                         if (child->color == card->color)
 333                                 parent = child;
 334                         else {
 335                                 fw_node_get(child);
 336                                 list_add_tail(&child->link, &list);
 337                         }
 338                 }
 339
 340                 callback(card, node, parent);
 341         }
 342
 343         list_for_each_entry_safe(node, next, &list, link)
 344                 fw_node_put(node);
 345 }
 346
 347 static void report_lost_node(struct fw_card *card,
 348                              struct fw_node *node, struct fw_node *parent)
 349 {
 350         fw_node_event(card, node, FW_NODE_DESTROYED);
 351         fw_node_put(node);
 352
 353         /* Topology has changed - reset bus manager retry counter */
 354         card->bm_retries = 0;
 355 }
 356
 357 static void report_found_node(struct fw_card *card,
 358                               struct fw_node *node, struct fw_node *parent)
 359 {
 360         int b_path = (node->phy_speed == SCODE_BETA);
 361
 362         if (parent != NULL) {
 363                 /* min() macro doesn't work here with gcc 3.4 */
 364                 node->max_speed = parent->max_speed < node->phy_speed ?
 365                                         parent->max_speed : node->phy_speed;
 366                 node->b_path = parent->b_path && b_path;
 367         } else {
 368                 node->max_speed = node->phy_speed;
 369                 node->b_path = b_path;
 370         }
 371
 372         fw_node_event(card, node, FW_NODE_CREATED);
 373
 374         /* Topology has changed - reset bus manager retry counter */
 375         card->bm_retries = 0;
 376 }
 377
 378 /* Must be called with card->lock held */
 379 void fw_destroy_nodes(struct fw_card *card)
 380 {
 381         card->color++;
 382         if (card->local_node != NULL)
 383                 for_each_fw_node(card, card->local_node, report_lost_node);
 384         card->local_node = NULL;
 385 }
 386
 387 static void move_tree(struct fw_node *node0, struct fw_node *node1, int port)
 388 {
 389         struct fw_node *tree;
 390         int i;
 391
 392         tree = node1->ports[port];
 393         node0->ports[port] = tree;
 394         for (i = 0; i < tree->port_count; i++) {
 395                 if (tree->ports[i] == node1) {
 396                         tree->ports[i] = node0;
 397                         break;
 398                 }
 399         }
 400 }
 401
 402 /*
 403  * Compare the old topology tree for card with the new one specified by root.
 404  * Queue the nodes and mark them as either found, lost or updated.
 405  * Update the nodes in the card topology tree as we go.
 406  */
 407 static void update_tree(struct fw_card *card, struct fw_node *root)
 408 {
 409         struct list_head list0, list1;
 410         struct fw_node *node0, *node1, *next1;
 411         int i, event;
 412
 413         INIT_LIST_HEAD(&list0);
 414         list_add_tail(&card->local_node->link, &list0);
 415         INIT_LIST_HEAD(&list1);
 416         list_add_tail(&root->link, &list1);
 417
 418         node0 = fw_node(list0.next);
 419         node1 = fw_node(list1.next);
 420
 421         while (&node0->link != &list0) {
 422                 WARN_ON(node0->port_count != node1->port_count);
 423
 424                 if (node0->link_on && !node1->link_on)
 425                         event = FW_NODE_LINK_OFF;
 426                 else if (!node0->link_on && node1->link_on)
 427                         event = FW_NODE_LINK_ON;
 428                 else if (node1->initiated_reset && node1->link_on)
 429                         event = FW_NODE_INITIATED_RESET;
 430                 else
 431                         event = FW_NODE_UPDATED;
 432
 433                 node0->node_id = node1->node_id;
 434                 node0->color = card->color;
 435                 node0->link_on = node1->link_on;
 436                 node0->initiated_reset = node1->initiated_reset;
 437                 node0->max_hops = node1->max_hops;
 438                 node1->color = card->color;
 439                 fw_node_event(card, node0, event);
 440
 441                 if (card->root_node == node1)
 442                         card->root_node = node0;
 443                 if (card->irm_node == node1)
 444                         card->irm_node = node0;
 445
 446                 for (i = 0; i < node0->port_count; i++) {
 447                         if (node0->ports[i] && node1->ports[i]) {
 448                                 /*
 449                                  * This port didn't change, queue the
 450                                  * connected node for further
 451                                  * investigation.
 452                                  */
 453                                 if (node0->ports[i]->color == card->color)
 454                                         continue;
 455                                 list_add_tail(&node0->ports[i]->link, &list0);
 456                                 list_add_tail(&node1->ports[i]->link, &list1);
 457                         } else if (node0->ports[i]) {
 458                                 /*
 459                                  * The nodes connected here were
 460                                  * unplugged; unref the lost nodes and
 461                                  * queue FW_NODE_LOST callbacks for
 462                                  * them.
 463                                  */
 464
 465                                 for_each_fw_node(card, node0->ports[i],
 466                                                  report_lost_node);
 467                                 node0->ports[i] = NULL;
 468                         } else if (node1->ports[i]) {
 469                                 /*
 470                                  * One or more node were connected to
 471                                  * this port. Move the new nodes into
 472                                  * the tree and queue FW_NODE_CREATED
 473                                  * callbacks for them.
 474                                  */
 475                                 move_tree(node0, node1, i);
 476                                 for_each_fw_node(card, node0->ports[i],
 477                                                  report_found_node);
 478                         }
 479                 }
 480
 481                 node0 = fw_node(node0->link.next);
 482                 next1 = fw_node(node1->link.next);
 483                 fw_node_put(node1);
 484                 node1 = next1;
 485         }
 486 }
 487
 488 static void update_topology_map(struct fw_card *card,
 489                                 u32 *self_ids, int self_id_count)
 490 {
 491         int node_count = (card->root_node->node_id & 0x3f) + 1;
 492         __be32 *map = card->topology_map;
 493
 494         *map++ = cpu_to_be32((self_id_count + 2) << 16);
 495         *map++ = cpu_to_be32(be32_to_cpu(card->topology_map[1]) + 1);
 496         *map++ = cpu_to_be32((node_count << 16) | self_id_count);
 497
 498         while (self_id_count--)
 499                 *map++ = cpu_to_be32p(self_ids++);
 500
 501         fw_compute_block_crc(card->topology_map);
 502 }
 503
 504 void fw_core_handle_bus_reset(struct fw_card *card, int node_id, int generation,
 505                               int self_id_count, u32 *self_ids, bool bm_abdicate)
 506 {
 507         struct fw_node *local_node;
 508         unsigned long flags;
 509
 510         spin_lock_irqsave(&card->lock, flags);
 511
 512         /*
 513          * If the selfID buffer is not the immediate successor of the
 514          * previously processed one, we cannot reliably compare the
 515          * old and new topologies.
 516          */
 517         if (!is_next_generation(generation, card->generation) &&
 518             card->local_node != NULL) {
 519                 fw_destroy_nodes(card);
 520                 card->bm_retries = 0;
 521         }
 522
 523         card->broadcast_channel_allocated = card->broadcast_channel_auto_allocated;
 524         card->node_id = node_id;
 525         /*
 526          * Update node_id before generation to prevent anybody from using
 527          * a stale node_id together with a current generation.
 528          */
 529         smp_wmb();
 530         card->generation = generation;
 531         card->reset_jiffies = get_jiffies_64();
 532         card->bm_node_id  = 0xffff;
 533         card->bm_abdicate = bm_abdicate;
 534         fw_schedule_bm_work(card, 0);
 535
 536         local_node = build_tree(card, self_ids, self_id_count);
 537
 538         update_topology_map(card, self_ids, self_id_count);
 539
 540         card->color++;
 541
 542         if (local_node == NULL) {
 543                 fw_err(card, "topology build failed\n");
 544                 /* FIXME: We need to issue a bus reset in this case. */
 545         } else if (card->local_node == NULL) {
 546                 card->local_node = local_node;
 547                 for_each_fw_node(card, local_node, report_found_node);
 548         } else {
 549                 update_tree(card, local_node);
 550         }
 551
 552         spin_unlock_irqrestore(&card->lock, flags);
 553 }
 554 EXPORT_SYMBOL(fw_core_handle_bus_reset);