xref: /linux/drivers/firewire/core-topology.c (revision 5d38cb9bee73969125c7818a9f9e3358e0db07d6)
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 #include "phy-packet-definitions.h"
24 #include <trace/events/firewire.h>
25 
fw_node_create(u32 sid,int port_count,int color)26 static struct fw_node *fw_node_create(u32 sid, int port_count, int color)
27 {
28 	struct fw_node *node;
29 
30 	node = kzalloc(struct_size(node, ports, port_count), GFP_ATOMIC);
31 	if (node == NULL)
32 		return NULL;
33 
34 	node->color = color;
35 	node->node_id = LOCAL_BUS | phy_packet_self_id_get_phy_id(sid);
36 	node->link_on = phy_packet_self_id_zero_get_link_active(sid);
37 	// NOTE: Only two bits, thus only for SCODE_100, SCODE_200, SCODE_400, and SCODE_BETA.
38 	node->phy_speed = phy_packet_self_id_zero_get_scode(sid);
39 	node->initiated_reset = phy_packet_self_id_zero_get_initiated_reset(sid);
40 	node->port_count = port_count;
41 
42 	kref_init(&node->kref);
43 	INIT_LIST_HEAD(&node->link);
44 
45 	return node;
46 }
47 
48 /*
49  * Compute the maximum hop count for this node and it's children.  The
50  * maximum hop count is the maximum number of connections between any
51  * two nodes in the subtree rooted at this node.  We need this for
52  * setting the gap count.  As we build the tree bottom up in
53  * build_tree() below, this is fairly easy to do: for each node we
54  * maintain the max hop count and the max depth, ie the number of hops
55  * to the furthest leaf.  Computing the max hop count breaks down into
56  * two cases: either the path goes through this node, in which case
57  * the hop count is the sum of the two biggest child depths plus 2.
58  * Or it could be the case that the max hop path is entirely
59  * contained in a child tree, in which case the max hop count is just
60  * the max hop count of this child.
61  */
update_hop_count(struct fw_node * node)62 static void update_hop_count(struct fw_node *node)
63 {
64 	int depths[2] = { -1, -1 };
65 	int max_child_hops = 0;
66 	int i;
67 
68 	for (i = 0; i < node->port_count; i++) {
69 		if (node->ports[i] == NULL)
70 			continue;
71 
72 		if (node->ports[i]->max_hops > max_child_hops)
73 			max_child_hops = node->ports[i]->max_hops;
74 
75 		if (node->ports[i]->max_depth > depths[0]) {
76 			depths[1] = depths[0];
77 			depths[0] = node->ports[i]->max_depth;
78 		} else if (node->ports[i]->max_depth > depths[1])
79 			depths[1] = node->ports[i]->max_depth;
80 	}
81 
82 	node->max_depth = depths[0] + 1;
83 	node->max_hops = max(max_child_hops, depths[0] + depths[1] + 2);
84 }
85 
fw_node(struct list_head * l)86 static inline struct fw_node *fw_node(struct list_head *l)
87 {
88 	return list_entry(l, struct fw_node, link);
89 }
90 
91 /*
92  * This function builds the tree representation of the topology given
93  * by the self IDs from the latest bus reset.  During the construction
94  * of the tree, the function checks that the self IDs are valid and
95  * internally consistent.  On success this function returns the
96  * fw_node corresponding to the local card otherwise NULL.
97  */
build_tree(struct fw_card * card,const u32 * sid,int self_id_count,unsigned int generation)98 static struct fw_node *build_tree(struct fw_card *card, const u32 *sid, int self_id_count,
99 				  unsigned int generation)
100 {
101 	struct self_id_sequence_enumerator enumerator = {
102 		.cursor = sid,
103 		.quadlet_count = self_id_count,
104 	};
105 	struct fw_node *node, *child, *local_node, *irm_node;
106 	struct list_head stack;
107 	int phy_id, stack_depth;
108 	int gap_count;
109 	bool beta_repeaters_present;
110 
111 	local_node = NULL;
112 	node = NULL;
113 	INIT_LIST_HEAD(&stack);
114 	stack_depth = 0;
115 	phy_id = 0;
116 	irm_node = NULL;
117 	gap_count = phy_packet_self_id_zero_get_gap_count(*sid);
118 	beta_repeaters_present = false;
119 
120 	while (enumerator.quadlet_count > 0) {
121 		unsigned int child_port_count = 0;
122 		unsigned int total_port_count = 0;
123 		unsigned int parent_count = 0;
124 		unsigned int quadlet_count;
125 		const u32 *self_id_sequence;
126 		unsigned int port_capacity;
127 		enum phy_packet_self_id_port_status port_status;
128 		unsigned int port_index;
129 		struct list_head *h;
130 		int i;
131 
132 		self_id_sequence = self_id_sequence_enumerator_next(&enumerator, &quadlet_count);
133 		if (IS_ERR(self_id_sequence)) {
134 			if (PTR_ERR(self_id_sequence) != -ENODATA) {
135 				fw_err(card, "inconsistent extended self IDs: %ld\n",
136 				       PTR_ERR(self_id_sequence));
137 				return NULL;
138 			}
139 			break;
140 		}
141 
142 		port_capacity = self_id_sequence_get_port_capacity(quadlet_count);
143 		trace_self_id_sequence(card->index, self_id_sequence, quadlet_count, generation);
144 
145 		for (port_index = 0; port_index < port_capacity; ++port_index) {
146 			port_status = self_id_sequence_get_port_status(self_id_sequence, quadlet_count,
147 								       port_index);
148 			switch (port_status) {
149 			case PHY_PACKET_SELF_ID_PORT_STATUS_CHILD:
150 				++child_port_count;
151 				fallthrough;
152 			case PHY_PACKET_SELF_ID_PORT_STATUS_PARENT:
153 			case PHY_PACKET_SELF_ID_PORT_STATUS_NCONN:
154 				++total_port_count;
155 				fallthrough;
156 			case PHY_PACKET_SELF_ID_PORT_STATUS_NONE:
157 			default:
158 				break;
159 			}
160 		}
161 
162 		if (phy_id != phy_packet_self_id_get_phy_id(self_id_sequence[0])) {
163 			fw_err(card, "PHY ID mismatch in self ID: %d != %d\n",
164 			       phy_id, phy_packet_self_id_get_phy_id(self_id_sequence[0]));
165 			return NULL;
166 		}
167 
168 		if (child_port_count > stack_depth) {
169 			fw_err(card, "topology stack underflow\n");
170 			return NULL;
171 		}
172 
173 		/*
174 		 * Seek back from the top of our stack to find the
175 		 * start of the child nodes for this node.
176 		 */
177 		for (i = 0, h = &stack; i < child_port_count; i++)
178 			h = h->prev;
179 		/*
180 		 * When the stack is empty, this yields an invalid value,
181 		 * but that pointer will never be dereferenced.
182 		 */
183 		child = fw_node(h);
184 
185 		node = fw_node_create(self_id_sequence[0], total_port_count, card->color);
186 		if (node == NULL) {
187 			fw_err(card, "out of memory while building topology\n");
188 			return NULL;
189 		}
190 
191 		if (phy_id == (card->node_id & 0x3f))
192 			local_node = node;
193 
194 		if (phy_packet_self_id_zero_get_contender(self_id_sequence[0]))
195 			irm_node = node;
196 
197 		for (port_index = 0; port_index < total_port_count; ++port_index) {
198 			port_status = self_id_sequence_get_port_status(self_id_sequence, quadlet_count,
199 								       port_index);
200 			switch (port_status) {
201 			case PHY_PACKET_SELF_ID_PORT_STATUS_PARENT:
202 				// Who's your daddy?  We dont know the parent node at this time, so
203 				// we temporarily abuse node->color for remembering the entry in
204 				// the node->ports array where the parent node should be.  Later,
205 				// when we handle the parent node, we fix up the reference.
206 				++parent_count;
207 				node->color = port_index;
208 				break;
209 
210 			case PHY_PACKET_SELF_ID_PORT_STATUS_CHILD:
211 				node->ports[port_index] = child;
212 				// Fix up parent reference for this child node.
213 				child->ports[child->color] = node;
214 				child->color = card->color;
215 				child = fw_node(child->link.next);
216 				break;
217 			case PHY_PACKET_SELF_ID_PORT_STATUS_NCONN:
218 			case PHY_PACKET_SELF_ID_PORT_STATUS_NONE:
219 			default:
220 				break;
221 			}
222 		}
223 
224 		// Check that the node reports exactly one parent port, except for the root, which
225 		// of course should have no parents.
226 		if ((enumerator.quadlet_count == 0 && parent_count != 0) ||
227 		    (enumerator.quadlet_count > 0 && parent_count != 1)) {
228 			fw_err(card, "parent port inconsistency for node %d: "
229 			       "parent_count=%d\n", phy_id, parent_count);
230 			return NULL;
231 		}
232 
233 		/* Pop the child nodes off the stack and push the new node. */
234 		__list_del(h->prev, &stack);
235 		list_add_tail(&node->link, &stack);
236 		stack_depth += 1 - child_port_count;
237 
238 		if (node->phy_speed == SCODE_BETA && parent_count + child_port_count > 1)
239 			beta_repeaters_present = true;
240 
241 		// If PHYs report different gap counts, set an invalid count which will force a gap
242 		// count reconfiguration and a reset.
243 		if (phy_packet_self_id_zero_get_gap_count(self_id_sequence[0]) != gap_count)
244 			gap_count = 0;
245 
246 		update_hop_count(node);
247 
248 		phy_id++;
249 	}
250 
251 	card->root_node = node;
252 	card->irm_node = irm_node;
253 	card->gap_count = gap_count;
254 	card->beta_repeaters_present = beta_repeaters_present;
255 
256 	return local_node;
257 }
258 
259 typedef void (*fw_node_callback_t)(struct fw_card * card,
260 				   struct fw_node * node,
261 				   struct fw_node * parent);
262 
for_each_fw_node(struct fw_card * card,struct fw_node * root,fw_node_callback_t callback)263 static void for_each_fw_node(struct fw_card *card, struct fw_node *root,
264 			     fw_node_callback_t callback)
265 {
266 	struct list_head list;
267 	struct fw_node *node, *next, *child, *parent;
268 	int i;
269 
270 	INIT_LIST_HEAD(&list);
271 
272 	fw_node_get(root);
273 	list_add_tail(&root->link, &list);
274 	parent = NULL;
275 	list_for_each_entry(node, &list, link) {
276 		node->color = card->color;
277 
278 		for (i = 0; i < node->port_count; i++) {
279 			child = node->ports[i];
280 			if (!child)
281 				continue;
282 			if (child->color == card->color)
283 				parent = child;
284 			else {
285 				fw_node_get(child);
286 				list_add_tail(&child->link, &list);
287 			}
288 		}
289 
290 		callback(card, node, parent);
291 	}
292 
293 	list_for_each_entry_safe(node, next, &list, link)
294 		fw_node_put(node);
295 }
296 
report_lost_node(struct fw_card * card,struct fw_node * node,struct fw_node * parent)297 static void report_lost_node(struct fw_card *card,
298 			     struct fw_node *node, struct fw_node *parent)
299 {
300 	fw_node_event(card, node, FW_NODE_DESTROYED);
301 	fw_node_put(node);
302 
303 	/* Topology has changed - reset bus manager retry counter */
304 	card->bm_retries = 0;
305 }
306 
report_found_node(struct fw_card * card,struct fw_node * node,struct fw_node * parent)307 static void report_found_node(struct fw_card *card,
308 			      struct fw_node *node, struct fw_node *parent)
309 {
310 	int b_path = (node->phy_speed == SCODE_BETA);
311 
312 	if (parent != NULL) {
313 		/* min() macro doesn't work here with gcc 3.4 */
314 		node->max_speed = parent->max_speed < node->phy_speed ?
315 					parent->max_speed : node->phy_speed;
316 		node->b_path = parent->b_path && b_path;
317 	} else {
318 		node->max_speed = node->phy_speed;
319 		node->b_path = b_path;
320 	}
321 
322 	fw_node_event(card, node, FW_NODE_CREATED);
323 
324 	/* Topology has changed - reset bus manager retry counter */
325 	card->bm_retries = 0;
326 }
327 
328 /* Must be called with card->lock held */
fw_destroy_nodes(struct fw_card * card)329 void fw_destroy_nodes(struct fw_card *card)
330 {
331 	card->color++;
332 	if (card->local_node != NULL)
333 		for_each_fw_node(card, card->local_node, report_lost_node);
334 	card->local_node = NULL;
335 }
336 
move_tree(struct fw_node * node0,struct fw_node * node1,int port)337 static void move_tree(struct fw_node *node0, struct fw_node *node1, int port)
338 {
339 	struct fw_node *tree;
340 	int i;
341 
342 	tree = node1->ports[port];
343 	node0->ports[port] = tree;
344 	for (i = 0; i < tree->port_count; i++) {
345 		if (tree->ports[i] == node1) {
346 			tree->ports[i] = node0;
347 			break;
348 		}
349 	}
350 }
351 
352 /*
353  * Compare the old topology tree for card with the new one specified by root.
354  * Queue the nodes and mark them as either found, lost or updated.
355  * Update the nodes in the card topology tree as we go.
356  */
update_tree(struct fw_card * card,struct fw_node * root)357 static void update_tree(struct fw_card *card, struct fw_node *root)
358 {
359 	struct list_head list0, list1;
360 	struct fw_node *node0, *node1, *next1;
361 	int i, event;
362 
363 	INIT_LIST_HEAD(&list0);
364 	list_add_tail(&card->local_node->link, &list0);
365 	INIT_LIST_HEAD(&list1);
366 	list_add_tail(&root->link, &list1);
367 
368 	node0 = fw_node(list0.next);
369 	node1 = fw_node(list1.next);
370 
371 	while (&node0->link != &list0) {
372 		WARN_ON(node0->port_count != node1->port_count);
373 
374 		if (node0->link_on && !node1->link_on)
375 			event = FW_NODE_LINK_OFF;
376 		else if (!node0->link_on && node1->link_on)
377 			event = FW_NODE_LINK_ON;
378 		else if (node1->initiated_reset && node1->link_on)
379 			event = FW_NODE_INITIATED_RESET;
380 		else
381 			event = FW_NODE_UPDATED;
382 
383 		node0->node_id = node1->node_id;
384 		node0->color = card->color;
385 		node0->link_on = node1->link_on;
386 		node0->initiated_reset = node1->initiated_reset;
387 		node0->max_hops = node1->max_hops;
388 		node1->color = card->color;
389 		fw_node_event(card, node0, event);
390 
391 		if (card->root_node == node1)
392 			card->root_node = node0;
393 		if (card->irm_node == node1)
394 			card->irm_node = node0;
395 
396 		for (i = 0; i < node0->port_count; i++) {
397 			if (node0->ports[i] && node1->ports[i]) {
398 				/*
399 				 * This port didn't change, queue the
400 				 * connected node for further
401 				 * investigation.
402 				 */
403 				if (node0->ports[i]->color == card->color)
404 					continue;
405 				list_add_tail(&node0->ports[i]->link, &list0);
406 				list_add_tail(&node1->ports[i]->link, &list1);
407 			} else if (node0->ports[i]) {
408 				/*
409 				 * The nodes connected here were
410 				 * unplugged; unref the lost nodes and
411 				 * queue FW_NODE_LOST callbacks for
412 				 * them.
413 				 */
414 
415 				for_each_fw_node(card, node0->ports[i],
416 						 report_lost_node);
417 				node0->ports[i] = NULL;
418 			} else if (node1->ports[i]) {
419 				/*
420 				 * One or more node were connected to
421 				 * this port. Move the new nodes into
422 				 * the tree and queue FW_NODE_CREATED
423 				 * callbacks for them.
424 				 */
425 				move_tree(node0, node1, i);
426 				for_each_fw_node(card, node0->ports[i],
427 						 report_found_node);
428 			}
429 		}
430 
431 		node0 = fw_node(node0->link.next);
432 		next1 = fw_node(node1->link.next);
433 		fw_node_put(node1);
434 		node1 = next1;
435 	}
436 }
437 
update_topology_map(struct fw_card * card,u32 * self_ids,int self_id_count)438 static void update_topology_map(struct fw_card *card,
439 				u32 *self_ids, int self_id_count)
440 {
441 	int node_count = (card->root_node->node_id & 0x3f) + 1;
442 	__be32 *map = card->topology_map;
443 
444 	*map++ = cpu_to_be32((self_id_count + 2) << 16);
445 	*map++ = cpu_to_be32(be32_to_cpu(card->topology_map[1]) + 1);
446 	*map++ = cpu_to_be32((node_count << 16) | self_id_count);
447 
448 	while (self_id_count--)
449 		*map++ = cpu_to_be32p(self_ids++);
450 
451 	fw_compute_block_crc(card->topology_map);
452 }
453 
fw_core_handle_bus_reset(struct fw_card * card,int node_id,int generation,int self_id_count,u32 * self_ids,bool bm_abdicate)454 void fw_core_handle_bus_reset(struct fw_card *card, int node_id, int generation,
455 			      int self_id_count, u32 *self_ids, bool bm_abdicate)
456 {
457 	struct fw_node *local_node;
458 
459 	trace_bus_reset_handle(card->index, generation, node_id, bm_abdicate, self_ids, self_id_count);
460 
461 	guard(spinlock_irqsave)(&card->lock);
462 
463 	/*
464 	 * If the selfID buffer is not the immediate successor of the
465 	 * previously processed one, we cannot reliably compare the
466 	 * old and new topologies.
467 	 */
468 	if (!is_next_generation(generation, card->generation) &&
469 	    card->local_node != NULL) {
470 		fw_destroy_nodes(card);
471 		card->bm_retries = 0;
472 	}
473 
474 	card->broadcast_channel_allocated = card->broadcast_channel_auto_allocated;
475 	card->node_id = node_id;
476 	/*
477 	 * Update node_id before generation to prevent anybody from using
478 	 * a stale node_id together with a current generation.
479 	 */
480 	smp_wmb();
481 	card->generation = generation;
482 	card->reset_jiffies = get_jiffies_64();
483 	card->bm_node_id  = 0xffff;
484 	card->bm_abdicate = bm_abdicate;
485 	fw_schedule_bm_work(card, 0);
486 
487 	local_node = build_tree(card, self_ids, self_id_count, generation);
488 
489 	update_topology_map(card, self_ids, self_id_count);
490 
491 	card->color++;
492 
493 	if (local_node == NULL) {
494 		fw_err(card, "topology build failed\n");
495 		/* FIXME: We need to issue a bus reset in this case. */
496 	} else if (card->local_node == NULL) {
497 		card->local_node = local_node;
498 		for_each_fw_node(card, local_node, report_found_node);
499 	} else {
500 		update_tree(card, local_node);
501 	}
502 }
503 EXPORT_SYMBOL(fw_core_handle_bus_reset);
504