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);
555