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 <[email protected]>
   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 #include <trace/events/firewire.h>
  24
  25 #define SELF_ID_PHY_ID(q)               (((q) >> 24) & 0x3f)
  26 #define SELF_ID_EXTENDED(q)             (((q) >> 23) & 0x01)
  27 #define SELF_ID_LINK_ON(q)              (((q) >> 22) & 0x01)
  28 #define SELF_ID_GAP_COUNT(q)            (((q) >> 16) & 0x3f)
  29 #define SELF_ID_PHY_SPEED(q)            (((q) >> 14) & 0x03)
  30 #define SELF_ID_CONTENDER(q)            (((q) >> 11) & 0x01)
  31 #define SELF_ID_PHY_INITIATOR(q)        (((q) >>  1) & 0x01)
  32 #define SELF_ID_MORE_PACKETS(q)         (((q) >>  0) & 0x01)
  33
  34 #define SELF_ID_EXT_SEQUENCE(q)         (((q) >> 20) & 0x07)
  35
  36 #define SELFID_PORT_CHILD       0x3
  37 #define SELFID_PORT_PARENT      0x2
  38 #define SELFID_PORT_NCONN       0x1
  39 #define SELFID_PORT_NONE        0x0
  40
  41 static u32 *count_ports(u32 *sid, int *total_port_count, int *child_port_count)
  42 {
  43         u32 q;
  44         int port_type, shift, seq;
  45
  46         *total_port_count = 0;
  47         *child_port_count = 0;
  48
  49         shift = 6;
  50         q = *sid;
  51         seq = 0;
  52
  53         while (1) {
  54                 port_type = (q >> shift) & 0x03;
  55                 switch (port_type) {
  56                 case SELFID_PORT_CHILD:
  57                         (*child_port_count)++;
  58                         fallthrough;
  59                 case SELFID_PORT_PARENT:
  60                 case SELFID_PORT_NCONN:
  61                         (*total_port_count)++;
  62                         fallthrough;
  63                 case SELFID_PORT_NONE:
  64                         break;
  65                 }
  66
  67                 shift -= 2;
  68                 if (shift == 0) {
  69                         if (!SELF_ID_MORE_PACKETS(q))
  70                                 return sid + 1;
  71
  72                         shift = 16;
  73                         sid++;
  74                         q = *sid;
  75
  76                         /*
  77                          * Check that the extra packets actually are
  78                          * extended self ID packets and that the
  79                          * sequence numbers in the extended self ID
  80                          * packets increase as expected.
  81                          */
  82
  83                         if (!SELF_ID_EXTENDED(q) ||
  84                             seq != SELF_ID_EXT_SEQUENCE(q))
  85                                 return NULL;
  86
  87                         seq++;
  88                 }
  89         }
  90 }
  91
  92 static int get_port_type(u32 *sid, int port_index)
  93 {
  94         int index, shift;
  95
  96         index = (port_index + 5) / 8;
  97         shift = 16 - ((port_index + 5) & 7) * 2;
  98         return (sid[index] >> shift) & 0x03;
  99 }
 100
 101 static struct fw_node *fw_node_create(u32 sid, int port_count, int color)
 102 {
 103         struct fw_node *node;
 104
 105         node = kzalloc(struct_size(node, ports, port_count), GFP_ATOMIC);
 106         if (node == NULL)
 107                 return NULL;
 108
 109         node->color = color;
 110         node->node_id = LOCAL_BUS | SELF_ID_PHY_ID(sid);
 111         node->link_on = SELF_ID_LINK_ON(sid);
 112         node->phy_speed = SELF_ID_PHY_SPEED(sid);
 113         node->initiated_reset = SELF_ID_PHY_INITIATOR(sid);
 114         node->port_count = port_count;
 115
 116         refcount_set(&node->ref_count, 1);
 117         INIT_LIST_HEAD(&node->link);
 118
 119         return node;
 120 }
 121
 122 /*
 123  * Compute the maximum hop count for this node and it's children.  The
 124  * maximum hop count is the maximum number of connections between any
 125  * two nodes in the subtree rooted at this node.  We need this for
 126  * setting the gap count.  As we build the tree bottom up in
 127  * build_tree() below, this is fairly easy to do: for each node we
 128  * maintain the max hop count and the max depth, ie the number of hops
 129  * to the furthest leaf.  Computing the max hop count breaks down into
 130  * two cases: either the path goes through this node, in which case
 131  * the hop count is the sum of the two biggest child depths plus 2.
 132  * Or it could be the case that the max hop path is entirely
 133  * containted in a child tree, in which case the max hop count is just
 134  * the max hop count of this child.
 135  */
 136 static void update_hop_count(struct fw_node *node)
 137 {
 138         int depths[2] = { -1, -1 };
 139         int max_child_hops = 0;
 140         int i;
 141
 142         for (i = 0; i < node->port_count; i++) {
 143                 if (node->ports[i] == NULL)
 144                         continue;
 145
 146                 if (node->ports[i]->max_hops > max_child_hops)
 147                         max_child_hops = node->ports[i]->max_hops;
 148
 149                 if (node->ports[i]->max_depth > depths[0]) {
 150                         depths[1] = depths[0];
 151                         depths[0] = node->ports[i]->max_depth;
 152                 } else if (node->ports[i]->max_depth > depths[1])
 153                         depths[1] = node->ports[i]->max_depth;
 154         }
 155
 156         node->max_depth = depths[0] + 1;
 157         node->max_hops = max(max_child_hops, depths[0] + depths[1] + 2);
 158 }
 159
 160 static inline struct fw_node *fw_node(struct list_head *l)
 161 {
 162         return list_entry(l, struct fw_node, link);
 163 }
 164
 165 /*
 166  * This function builds the tree representation of the topology given
 167  * by the self IDs from the latest bus reset.  During the construction
 168  * of the tree, the function checks that the self IDs are valid and
 169  * internally consistent.  On success this function returns the
 170  * fw_node corresponding to the local card otherwise NULL.
 171  */
 172 static struct fw_node *build_tree(struct fw_card *card,
 173                                   u32 *sid, int self_id_count)
 174 {
 175         struct fw_node *node, *child, *local_node, *irm_node;
 176         struct list_head stack, *h;
 177         u32 *next_sid, *end, q;
 178         int i, port_count, child_port_count, phy_id, parent_count, stack_depth;
 179         int gap_count;
 180         bool beta_repeaters_present;
 181
 182         local_node = NULL;
 183         node = NULL;
 184         INIT_LIST_HEAD(&stack);
 185         stack_depth = 0;
 186         end = sid + self_id_count;
 187         phy_id = 0;
 188         irm_node = NULL;
 189         gap_count = SELF_ID_GAP_COUNT(*sid);
 190         beta_repeaters_present = false;
 191
 192         while (sid < end) {
 193                 next_sid = count_ports(sid, &port_count, &child_port_count);
 194
 195                 if (next_sid == NULL) {
 196                         fw_err(card, "inconsistent extended self IDs\n");
 197                         return NULL;
 198                 }
 199
 200                 q = *sid;
 201                 if (phy_id != SELF_ID_PHY_ID(q)) {
 202                         fw_err(card, "PHY ID mismatch in self ID: %d != %d\n",
 203                                phy_id, SELF_ID_PHY_ID(q));
 204                         return NULL;
 205                 }
 206
 207                 if (child_port_count > stack_depth) {
 208                         fw_err(card, "topology stack underflow\n");
 209                         return NULL;
 210                 }
 211
 212                 /*
 213                  * Seek back from the top of our stack to find the
 214                  * start of the child nodes for this node.
 215                  */
 216                 for (i = 0, h = &stack; i < child_port_count; i++)
 217                         h = h->prev;
 218                 /*
 219                  * When the stack is empty, this yields an invalid value,
 220                  * but that pointer will never be dereferenced.
 221                  */
 222                 child = fw_node(h);
 223
 224                 node = fw_node_create(q, port_count, card->color);
 225                 if (node == NULL) {
 226                         fw_err(card, "out of memory while building topology\n");
 227                         return NULL;
 228                 }
 229
 230                 if (phy_id == (card->node_id & 0x3f))
 231                         local_node = node;
 232
 233                 if (SELF_ID_CONTENDER(q))
 234                         irm_node = node;
 235
 236                 parent_count = 0;
 237
 238                 for (i = 0; i < port_count; i++) {
 239                         switch (get_port_type(sid, i)) {
 240                         case SELFID_PORT_PARENT:
 241                                 /*
 242                                  * Who's your daddy?  We dont know the
 243                                  * parent node at this time, so we
 244                                  * temporarily abuse node->color for
 245                                  * remembering the entry in the
 246                                  * node->ports array where the parent
 247                                  * node should be.  Later, when we
 248                                  * handle the parent node, we fix up
 249                                  * the reference.
 250                                  */
 251                                 parent_count++;
 252                                 node->color = i;
 253                                 break;
 254
 255                         case SELFID_PORT_CHILD:
 256                                 node->ports[i] = child;
 257                                 /*
 258                                  * Fix up parent reference for this
 259                                  * child node.
 260                                  */
 261                                 child->ports[child->color] = node;
 262                                 child->color = card->color;
 263                                 child = fw_node(child->link.next);
 264                                 break;
 265                         }
 266                 }
 267
 268                 /*
 269                  * Check that the node reports exactly one parent
 270                  * port, except for the root, which of course should
 271                  * have no parents.
 272                  */
 273                 if ((next_sid == end && parent_count != 0) ||
 274                     (next_sid < end && parent_count != 1)) {
 275                         fw_err(card, "parent port inconsistency for node %d: "
 276                                "parent_count=%d\n", phy_id, parent_count);
 277                         return NULL;
 278                 }
 279
 280                 /* Pop the child nodes off the stack and push the new node. */
 281                 __list_del(h->prev, &stack);
 282                 list_add_tail(&node->link, &stack);
 283                 stack_depth += 1 - child_port_count;
 284
 285                 if (node->phy_speed == SCODE_BETA &&
 286                     parent_count + child_port_count > 1)
 287                         beta_repeaters_present = true;
 288
 289                 /*
 290                  * If PHYs report different gap counts, set an invalid count
 291                  * which will force a gap count reconfiguration and a reset.
 292                  */
 293                 if (SELF_ID_GAP_COUNT(q) != gap_count)
 294                         gap_count = 0;
 295
 296                 update_hop_count(node);
 297
 298                 sid = next_sid;
 299                 phy_id++;
 300         }
 301
 302         card->root_node = node;
 303         card->irm_node = irm_node;
 304         card->gap_count = gap_count;
 305         card->beta_repeaters_present = beta_repeaters_present;
 306
 307         return local_node;
 308 }
 309
 310 typedef void (*fw_node_callback_t)(struct fw_card * card,
 311                                    struct fw_node * node,
 312                                    struct fw_node * parent);
 313
 314 static void for_each_fw_node(struct fw_card *card, struct fw_node *root,
 315                              fw_node_callback_t callback)
 316 {
 317         struct list_head list;
 318         struct fw_node *node, *next, *child, *parent;
 319         int i;
 320
 321         INIT_LIST_HEAD(&list);
 322
 323         fw_node_get(root);
 324         list_add_tail(&root->link, &list);
 325         parent = NULL;
 326         list_for_each_entry(node, &list, link) {
 327                 node->color = card->color;
 328
 329                 for (i = 0; i < node->port_count; i++) {
 330                         child = node->ports[i];
 331                         if (!child)
 332                                 continue;
 333                         if (child->color == card->color)
 334                                 parent = child;
 335                         else {
 336                                 fw_node_get(child);
 337                                 list_add_tail(&child->link, &list);
 338                         }
 339                 }
 340
 341                 callback(card, node, parent);
 342         }
 343
 344         list_for_each_entry_safe(node, next, &list, link)
 345                 fw_node_put(node);
 346 }
 347
 348 static void report_lost_node(struct fw_card *card,
 349                              struct fw_node *node, struct fw_node *parent)
 350 {
 351         fw_node_event(card, node, FW_NODE_DESTROYED);
 352         fw_node_put(node);
 353
 354         /* Topology has changed - reset bus manager retry counter */
 355         card->bm_retries = 0;
 356 }
 357
 358 static void report_found_node(struct fw_card *card,
 359                               struct fw_node *node, struct fw_node *parent)
 360 {
 361         int b_path = (node->phy_speed == SCODE_BETA);
 362
 363         if (parent != NULL) {
 364                 /* min() macro doesn't work here with gcc 3.4 */
 365                 node->max_speed = parent->max_speed < node->phy_speed ?
 366                                         parent->max_speed : node->phy_speed;
 367                 node->b_path = parent->b_path && b_path;
 368         } else {
 369                 node->max_speed = node->phy_speed;
 370                 node->b_path = b_path;
 371         }
 372
 373         fw_node_event(card, node, FW_NODE_CREATED);
 374
 375         /* Topology has changed - reset bus manager retry counter */
 376         card->bm_retries = 0;
 377 }
 378
 379 /* Must be called with card->lock held */
 380 void fw_destroy_nodes(struct fw_card *card)
 381 {
 382         card->color++;
 383         if (card->local_node != NULL)
 384                 for_each_fw_node(card, card->local_node, report_lost_node);
 385         card->local_node = NULL;
 386 }
 387
 388 static void move_tree(struct fw_node *node0, struct fw_node *node1, int port)
 389 {
 390         struct fw_node *tree;
 391         int i;
 392
 393         tree = node1->ports[port];
 394         node0->ports[port] = tree;
 395         for (i = 0; i < tree->port_count; i++) {
 396                 if (tree->ports[i] == node1) {
 397                         tree->ports[i] = node0;
 398                         break;
 399                 }
 400         }
 401 }
 402
 403 /*
 404  * Compare the old topology tree for card with the new one specified by root.
 405  * Queue the nodes and mark them as either found, lost or updated.
 406  * Update the nodes in the card topology tree as we go.
 407  */
 408 static void update_tree(struct fw_card *card, struct fw_node *root)
 409 {
 410         struct list_head list0, list1;
 411         struct fw_node *node0, *node1, *next1;
 412         int i, event;
 413
 414         INIT_LIST_HEAD(&list0);
 415         list_add_tail(&card->local_node->link, &list0);
 416         INIT_LIST_HEAD(&list1);
 417         list_add_tail(&root->link, &list1);
 418
 419         node0 = fw_node(list0.next);
 420         node1 = fw_node(list1.next);
 421
 422         while (&node0->link != &list0) {
 423                 WARN_ON(node0->port_count != node1->port_count);
 424
 425                 if (node0->link_on && !node1->link_on)
 426                         event = FW_NODE_LINK_OFF;
 427                 else if (!node0->link_on && node1->link_on)
 428                         event = FW_NODE_LINK_ON;
 429                 else if (node1->initiated_reset && node1->link_on)
 430                         event = FW_NODE_INITIATED_RESET;
 431                 else
 432                         event = FW_NODE_UPDATED;
 433
 434                 node0->node_id = node1->node_id;
 435                 node0->color = card->color;
 436                 node0->link_on = node1->link_on;
 437                 node0->initiated_reset = node1->initiated_reset;
 438                 node0->max_hops = node1->max_hops;
 439                 node1->color = card->color;
 440                 fw_node_event(card, node0, event);
 441
 442                 if (card->root_node == node1)
 443                         card->root_node = node0;
 444                 if (card->irm_node == node1)
 445                         card->irm_node = node0;
 446
 447                 for (i = 0; i < node0->port_count; i++) {
 448                         if (node0->ports[i] && node1->ports[i]) {
 449                                 /*
 450                                  * This port didn't change, queue the
 451                                  * connected node for further
 452                                  * investigation.
 453                                  */
 454                                 if (node0->ports[i]->color == card->color)
 455                                         continue;
 456                                 list_add_tail(&node0->ports[i]->link, &list0);
 457                                 list_add_tail(&node1->ports[i]->link, &list1);
 458                         } else if (node0->ports[i]) {
 459                                 /*
 460                                  * The nodes connected here were
 461                                  * unplugged; unref the lost nodes and
 462                                  * queue FW_NODE_LOST callbacks for
 463                                  * them.
 464                                  */
 465
 466                                 for_each_fw_node(card, node0->ports[i],
 467                                                  report_lost_node);
 468                                 node0->ports[i] = NULL;
 469                         } else if (node1->ports[i]) {
 470                                 /*
 471                                  * One or more node were connected to
 472                                  * this port. Move the new nodes into
 473                                  * the tree and queue FW_NODE_CREATED
 474                                  * callbacks for them.
 475                                  */
 476                                 move_tree(node0, node1, i);
 477                                 for_each_fw_node(card, node0->ports[i],
 478                                                  report_found_node);
 479                         }
 480                 }
 481
 482                 node0 = fw_node(node0->link.next);
 483                 next1 = fw_node(node1->link.next);
 484                 fw_node_put(node1);
 485                 node1 = next1;
 486         }
 487 }
 488
 489 static void update_topology_map(struct fw_card *card,
 490                                 u32 *self_ids, int self_id_count)
 491 {
 492         int node_count = (card->root_node->node_id & 0x3f) + 1;
 493         __be32 *map = card->topology_map;
 494
 495         *map++ = cpu_to_be32((self_id_count + 2) << 16);
 496         *map++ = cpu_to_be32(be32_to_cpu(card->topology_map[1]) + 1);
 497         *map++ = cpu_to_be32((node_count << 16) | self_id_count);
 498
 499         while (self_id_count--)
 500                 *map++ = cpu_to_be32p(self_ids++);
 501
 502         fw_compute_block_crc(card->topology_map);
 503 }
 504
 505 void fw_core_handle_bus_reset(struct fw_card *card, int node_id, int generation,
 506                               int self_id_count, u32 *self_ids, bool bm_abdicate)
 507 {
 508         struct fw_node *local_node;
 509         unsigned long flags;
 510
 511         trace_bus_reset_handle(generation, node_id, bm_abdicate, self_ids, self_id_count);
 512
 513         spin_lock_irqsave(&card->lock, flags);
 514
 515         /*
 516          * If the selfID buffer is not the immediate successor of the
 517          * previously processed one, we cannot reliably compare the
 518          * old and new topologies.
 519          */
 520         if (!is_next_generation(generation, card->generation) &&
 521             card->local_node != NULL) {
 522                 fw_destroy_nodes(card);
 523                 card->bm_retries = 0;
 524         }
 525
 526         card->broadcast_channel_allocated = card->broadcast_channel_auto_allocated;
 527         card->node_id = node_id;
 528         /*
 529          * Update node_id before generation to prevent anybody from using
 530          * a stale node_id together with a current generation.
 531          */
 532         smp_wmb();
 533         card->generation = generation;
 534         card->reset_jiffies = get_jiffies_64();
 535         card->bm_node_id  = 0xffff;
 536         card->bm_abdicate = bm_abdicate;
 537         fw_schedule_bm_work(card, 0);
 538
 539         local_node = build_tree(card, self_ids, self_id_count);
 540
 541         update_topology_map(card, self_ids, self_id_count);
 542
 543         card->color++;
 544
 545         if (local_node == NULL) {
 546                 fw_err(card, "topology build failed\n");
 547                 /* FIXME: We need to issue a bus reset in this case. */
 548         } else if (card->local_node == NULL) {
 549                 card->local_node = local_node;
 550                 for_each_fw_node(card, local_node, report_found_node);
 551         } else {
 552                 update_tree(card, local_node);
 553         }
 554
 555         spin_unlock_irqrestore(&card->lock, flags);
 556 }
 557 EXPORT_SYMBOL(fw_core_handle_bus_reset);