root/drivers/firewire/core-topology.c

DEFINITIONS

1. count_ports
2. get_port_type
3. fw_node_create
4. update_hop_count
5. build_tree
6. for_each_fw_node
7. report_lost_node
8. report_found_node
9. fw_destroy_nodes
10. move_tree
11. update_tree
12. update_topology_map
13. fw_core_handle_bus_reset

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