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 		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);
557