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 		case SELFID_PORT_PARENT:
58 		case SELFID_PORT_NCONN:
59 			(*total_port_count)++;
60 		case SELFID_PORT_NONE:
61 			break;
62 		}
63 
64 		shift -= 2;
65 		if (shift == 0) {
66 			if (!SELF_ID_MORE_PACKETS(q))
67 				return sid + 1;
68 
69 			shift = 16;
70 			sid++;
71 			q = *sid;
72 
73 			/*
74 			 * Check that the extra packets actually are
75 			 * extended self ID packets and that the
76 			 * sequence numbers in the extended self ID
77 			 * packets increase as expected.
78 			 */
79 
80 			if (!SELF_ID_EXTENDED(q) ||
81 			    seq != SELF_ID_EXT_SEQUENCE(q))
82 				return NULL;
83 
84 			seq++;
85 		}
86 	}
87 }
88 
89 static int get_port_type(u32 *sid, int port_index)
90 {
91 	int index, shift;
92 
93 	index = (port_index + 5) / 8;
94 	shift = 16 - ((port_index + 5) & 7) * 2;
95 	return (sid[index] >> shift) & 0x03;
96 }
97 
98 static struct fw_node *fw_node_create(u32 sid, int port_count, int color)
99 {
100 	struct fw_node *node;
101 
102 	node = kzalloc(struct_size(node, ports, port_count), GFP_ATOMIC);
103 	if (node == NULL)
104 		return NULL;
105 
106 	node->color = color;
107 	node->node_id = LOCAL_BUS | SELF_ID_PHY_ID(sid);
108 	node->link_on = SELF_ID_LINK_ON(sid);
109 	node->phy_speed = SELF_ID_PHY_SPEED(sid);
110 	node->initiated_reset = SELF_ID_PHY_INITIATOR(sid);
111 	node->port_count = port_count;
112 
113 	refcount_set(&node->ref_count, 1);
114 	INIT_LIST_HEAD(&node->link);
115 
116 	return node;
117 }
118 
119 /*
120  * Compute the maximum hop count for this node and it's children.  The
121  * maximum hop count is the maximum number of connections between any
122  * two nodes in the subtree rooted at this node.  We need this for
123  * setting the gap count.  As we build the tree bottom up in
124  * build_tree() below, this is fairly easy to do: for each node we
125  * maintain the max hop count and the max depth, ie the number of hops
126  * to the furthest leaf.  Computing the max hop count breaks down into
127  * two cases: either the path goes through this node, in which case
128  * the hop count is the sum of the two biggest child depths plus 2.
129  * Or it could be the case that the max hop path is entirely
130  * containted in a child tree, in which case the max hop count is just
131  * the max hop count of this child.
132  */
133 static void update_hop_count(struct fw_node *node)
134 {
135 	int depths[2] = { -1, -1 };
136 	int max_child_hops = 0;
137 	int i;
138 
139 	for (i = 0; i < node->port_count; i++) {
140 		if (node->ports[i] == NULL)
141 			continue;
142 
143 		if (node->ports[i]->max_hops > max_child_hops)
144 			max_child_hops = node->ports[i]->max_hops;
145 
146 		if (node->ports[i]->max_depth > depths[0]) {
147 			depths[1] = depths[0];
148 			depths[0] = node->ports[i]->max_depth;
149 		} else if (node->ports[i]->max_depth > depths[1])
150 			depths[1] = node->ports[i]->max_depth;
151 	}
152 
153 	node->max_depth = depths[0] + 1;
154 	node->max_hops = max(max_child_hops, depths[0] + depths[1] + 2);
155 }
156 
157 static inline struct fw_node *fw_node(struct list_head *l)
158 {
159 	return list_entry(l, struct fw_node, link);
160 }
161 
162 /*
163  * This function builds the tree representation of the topology given
164  * by the self IDs from the latest bus reset.  During the construction
165  * of the tree, the function checks that the self IDs are valid and
166  * internally consistent.  On success this function returns the
167  * fw_node corresponding to the local card otherwise NULL.
168  */
169 static struct fw_node *build_tree(struct fw_card *card,
170 				  u32 *sid, int self_id_count)
171 {
172 	struct fw_node *node, *child, *local_node, *irm_node;
173 	struct list_head stack, *h;
174 	u32 *next_sid, *end, q;
175 	int i, port_count, child_port_count, phy_id, parent_count, stack_depth;
176 	int gap_count;
177 	bool beta_repeaters_present;
178 
179 	local_node = NULL;
180 	node = NULL;
181 	INIT_LIST_HEAD(&stack);
182 	stack_depth = 0;
183 	end = sid + self_id_count;
184 	phy_id = 0;
185 	irm_node = NULL;
186 	gap_count = SELF_ID_GAP_COUNT(*sid);
187 	beta_repeaters_present = false;
188 
189 	while (sid < end) {
190 		next_sid = count_ports(sid, &port_count, &child_port_count);
191 
192 		if (next_sid == NULL) {
193 			fw_err(card, "inconsistent extended self IDs\n");
194 			return NULL;
195 		}
196 
197 		q = *sid;
198 		if (phy_id != SELF_ID_PHY_ID(q)) {
199 			fw_err(card, "PHY ID mismatch in self ID: %d != %d\n",
200 			       phy_id, SELF_ID_PHY_ID(q));
201 			return NULL;
202 		}
203 
204 		if (child_port_count > stack_depth) {
205 			fw_err(card, "topology stack underflow\n");
206 			return NULL;
207 		}
208 
209 		/*
210 		 * Seek back from the top of our stack to find the
211 		 * start of the child nodes for this node.
212 		 */
213 		for (i = 0, h = &stack; i < child_port_count; i++)
214 			h = h->prev;
215 		/*
216 		 * When the stack is empty, this yields an invalid value,
217 		 * but that pointer will never be dereferenced.
218 		 */
219 		child = fw_node(h);
220 
221 		node = fw_node_create(q, port_count, card->color);
222 		if (node == NULL) {
223 			fw_err(card, "out of memory while building topology\n");
224 			return NULL;
225 		}
226 
227 		if (phy_id == (card->node_id & 0x3f))
228 			local_node = node;
229 
230 		if (SELF_ID_CONTENDER(q))
231 			irm_node = node;
232 
233 		parent_count = 0;
234 
235 		for (i = 0; i < port_count; i++) {
236 			switch (get_port_type(sid, i)) {
237 			case SELFID_PORT_PARENT:
238 				/*
239 				 * Who's your daddy?  We dont know the
240 				 * parent node at this time, so we
241 				 * temporarily abuse node->color for
242 				 * remembering the entry in the
243 				 * node->ports array where the parent
244 				 * node should be.  Later, when we
245 				 * handle the parent node, we fix up
246 				 * the reference.
247 				 */
248 				parent_count++;
249 				node->color = i;
250 				break;
251 
252 			case SELFID_PORT_CHILD:
253 				node->ports[i] = child;
254 				/*
255 				 * Fix up parent reference for this
256 				 * child node.
257 				 */
258 				child->ports[child->color] = node;
259 				child->color = card->color;
260 				child = fw_node(child->link.next);
261 				break;
262 			}
263 		}
264 
265 		/*
266 		 * Check that the node reports exactly one parent
267 		 * port, except for the root, which of course should
268 		 * have no parents.
269 		 */
270 		if ((next_sid == end && parent_count != 0) ||
271 		    (next_sid < end && parent_count != 1)) {
272 			fw_err(card, "parent port inconsistency for node %d: "
273 			       "parent_count=%d\n", phy_id, parent_count);
274 			return NULL;
275 		}
276 
277 		/* Pop the child nodes off the stack and push the new node. */
278 		__list_del(h->prev, &stack);
279 		list_add_tail(&node->link, &stack);
280 		stack_depth += 1 - child_port_count;
281 
282 		if (node->phy_speed == SCODE_BETA &&
283 		    parent_count + child_port_count > 1)
284 			beta_repeaters_present = true;
285 
286 		/*
287 		 * If PHYs report different gap counts, set an invalid count
288 		 * which will force a gap count reconfiguration and a reset.
289 		 */
290 		if (SELF_ID_GAP_COUNT(q) != gap_count)
291 			gap_count = 0;
292 
293 		update_hop_count(node);
294 
295 		sid = next_sid;
296 		phy_id++;
297 	}
298 
299 	card->root_node = node;
300 	card->irm_node = irm_node;
301 	card->gap_count = gap_count;
302 	card->beta_repeaters_present = beta_repeaters_present;
303 
304 	return local_node;
305 }
306 
307 typedef void (*fw_node_callback_t)(struct fw_card * card,
308 				   struct fw_node * node,
309 				   struct fw_node * parent);
310 
311 static void for_each_fw_node(struct fw_card *card, struct fw_node *root,
312 			     fw_node_callback_t callback)
313 {
314 	struct list_head list;
315 	struct fw_node *node, *next, *child, *parent;
316 	int i;
317 
318 	INIT_LIST_HEAD(&list);
319 
320 	fw_node_get(root);
321 	list_add_tail(&root->link, &list);
322 	parent = NULL;
323 	list_for_each_entry(node, &list, link) {
324 		node->color = card->color;
325 
326 		for (i = 0; i < node->port_count; i++) {
327 			child = node->ports[i];
328 			if (!child)
329 				continue;
330 			if (child->color == card->color)
331 				parent = child;
332 			else {
333 				fw_node_get(child);
334 				list_add_tail(&child->link, &list);
335 			}
336 		}
337 
338 		callback(card, node, parent);
339 	}
340 
341 	list_for_each_entry_safe(node, next, &list, link)
342 		fw_node_put(node);
343 }
344 
345 static void report_lost_node(struct fw_card *card,
346 			     struct fw_node *node, struct fw_node *parent)
347 {
348 	fw_node_event(card, node, FW_NODE_DESTROYED);
349 	fw_node_put(node);
350 
351 	/* Topology has changed - reset bus manager retry counter */
352 	card->bm_retries = 0;
353 }
354 
355 static void report_found_node(struct fw_card *card,
356 			      struct fw_node *node, struct fw_node *parent)
357 {
358 	int b_path = (node->phy_speed == SCODE_BETA);
359 
360 	if (parent != NULL) {
361 		/* min() macro doesn't work here with gcc 3.4 */
362 		node->max_speed = parent->max_speed < node->phy_speed ?
363 					parent->max_speed : node->phy_speed;
364 		node->b_path = parent->b_path && b_path;
365 	} else {
366 		node->max_speed = node->phy_speed;
367 		node->b_path = b_path;
368 	}
369 
370 	fw_node_event(card, node, FW_NODE_CREATED);
371 
372 	/* Topology has changed - reset bus manager retry counter */
373 	card->bm_retries = 0;
374 }
375 
376 void fw_destroy_nodes(struct fw_card *card)
377 {
378 	unsigned long flags;
379 
380 	spin_lock_irqsave(&card->lock, flags);
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 	spin_unlock_irqrestore(&card->lock, flags);
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 	/*
512 	 * If the selfID buffer is not the immediate successor of the
513 	 * previously processed one, we cannot reliably compare the
514 	 * old and new topologies.
515 	 */
516 	if (!is_next_generation(generation, card->generation) &&
517 	    card->local_node != NULL) {
518 		fw_destroy_nodes(card);
519 		card->bm_retries = 0;
520 	}
521 
522 	spin_lock_irqsave(&card->lock, flags);
523 
524 	card->broadcast_channel_allocated = card->broadcast_channel_auto_allocated;
525 	card->node_id = node_id;
526 	/*
527 	 * Update node_id before generation to prevent anybody from using
528 	 * a stale node_id together with a current generation.
529 	 */
530 	smp_wmb();
531 	card->generation = generation;
532 	card->reset_jiffies = get_jiffies_64();
533 	card->bm_node_id  = 0xffff;
534 	card->bm_abdicate = bm_abdicate;
535 	fw_schedule_bm_work(card, 0);
536 
537 	local_node = build_tree(card, self_ids, self_id_count);
538 
539 	update_topology_map(card, self_ids, self_id_count);
540 
541 	card->color++;
542 
543 	if (local_node == NULL) {
544 		fw_err(card, "topology build failed\n");
545 		/* FIXME: We need to issue a bus reset in this case. */
546 	} else if (card->local_node == NULL) {
547 		card->local_node = local_node;
548 		for_each_fw_node(card, local_node, report_found_node);
549 	} else {
550 		update_tree(card, local_node);
551 	}
552 
553 	spin_unlock_irqrestore(&card->lock, flags);
554 }
555 EXPORT_SYMBOL(fw_core_handle_bus_reset);
556