1 /*
2  * Incremental bus scan, based on bus topology
3  *
4  * Copyright (C) 2004-2006 Kristian Hoegsberg <krh@bitplanet.net>
5  *
6  * This program is free software; you can redistribute it and/or modify
7  * it under the terms of the GNU General Public License as published by
8  * the Free Software Foundation; either version 2 of the License, or
9  * (at your option) any later version.
10  *
11  * This program is distributed in the hope that it will be useful,
12  * but WITHOUT ANY WARRANTY; without even the implied warranty of
13  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
14  * GNU General Public License for more details.
15  *
16  * You should have received a copy of the GNU General Public License
17  * along with this program; if not, write to the Free Software Foundation,
18  * Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
19  */
20 
21 #include <linux/bug.h>
22 #include <linux/errno.h>
23 #include <linux/firewire.h>
24 #include <linux/firewire-constants.h>
25 #include <linux/jiffies.h>
26 #include <linux/kernel.h>
27 #include <linux/list.h>
28 #include <linux/module.h>
29 #include <linux/slab.h>
30 #include <linux/spinlock.h>
31 
32 #include <linux/atomic.h>
33 #include <asm/byteorder.h>
34 
35 #include "core.h"
36 
37 #define SELF_ID_PHY_ID(q)		(((q) >> 24) & 0x3f)
38 #define SELF_ID_EXTENDED(q)		(((q) >> 23) & 0x01)
39 #define SELF_ID_LINK_ON(q)		(((q) >> 22) & 0x01)
40 #define SELF_ID_GAP_COUNT(q)		(((q) >> 16) & 0x3f)
41 #define SELF_ID_PHY_SPEED(q)		(((q) >> 14) & 0x03)
42 #define SELF_ID_CONTENDER(q)		(((q) >> 11) & 0x01)
43 #define SELF_ID_PHY_INITIATOR(q)	(((q) >>  1) & 0x01)
44 #define SELF_ID_MORE_PACKETS(q)		(((q) >>  0) & 0x01)
45 
46 #define SELF_ID_EXT_SEQUENCE(q)		(((q) >> 20) & 0x07)
47 
48 #define SELFID_PORT_CHILD	0x3
49 #define SELFID_PORT_PARENT	0x2
50 #define SELFID_PORT_NCONN	0x1
51 #define SELFID_PORT_NONE	0x0
52 
53 static u32 *count_ports(u32 *sid, int *total_port_count, int *child_port_count)
54 {
55 	u32 q;
56 	int port_type, shift, seq;
57 
58 	*total_port_count = 0;
59 	*child_port_count = 0;
60 
61 	shift = 6;
62 	q = *sid;
63 	seq = 0;
64 
65 	while (1) {
66 		port_type = (q >> shift) & 0x03;
67 		switch (port_type) {
68 		case SELFID_PORT_CHILD:
69 			(*child_port_count)++;
70 		case SELFID_PORT_PARENT:
71 		case SELFID_PORT_NCONN:
72 			(*total_port_count)++;
73 		case SELFID_PORT_NONE:
74 			break;
75 		}
76 
77 		shift -= 2;
78 		if (shift == 0) {
79 			if (!SELF_ID_MORE_PACKETS(q))
80 				return sid + 1;
81 
82 			shift = 16;
83 			sid++;
84 			q = *sid;
85 
86 			/*
87 			 * Check that the extra packets actually are
88 			 * extended self ID packets and that the
89 			 * sequence numbers in the extended self ID
90 			 * packets increase as expected.
91 			 */
92 
93 			if (!SELF_ID_EXTENDED(q) ||
94 			    seq != SELF_ID_EXT_SEQUENCE(q))
95 				return NULL;
96 
97 			seq++;
98 		}
99 	}
100 }
101 
102 static int get_port_type(u32 *sid, int port_index)
103 {
104 	int index, shift;
105 
106 	index = (port_index + 5) / 8;
107 	shift = 16 - ((port_index + 5) & 7) * 2;
108 	return (sid[index] >> shift) & 0x03;
109 }
110 
111 static struct fw_node *fw_node_create(u32 sid, int port_count, int color)
112 {
113 	struct fw_node *node;
114 
115 	node = kzalloc(sizeof(*node) + port_count * sizeof(node->ports[0]),
116 		       GFP_ATOMIC);
117 	if (node == NULL)
118 		return NULL;
119 
120 	node->color = color;
121 	node->node_id = LOCAL_BUS | SELF_ID_PHY_ID(sid);
122 	node->link_on = SELF_ID_LINK_ON(sid);
123 	node->phy_speed = SELF_ID_PHY_SPEED(sid);
124 	node->initiated_reset = SELF_ID_PHY_INITIATOR(sid);
125 	node->port_count = port_count;
126 
127 	refcount_set(&node->ref_count, 1);
128 	INIT_LIST_HEAD(&node->link);
129 
130 	return node;
131 }
132 
133 /*
134  * Compute the maximum hop count for this node and it's children.  The
135  * maximum hop count is the maximum number of connections between any
136  * two nodes in the subtree rooted at this node.  We need this for
137  * setting the gap count.  As we build the tree bottom up in
138  * build_tree() below, this is fairly easy to do: for each node we
139  * maintain the max hop count and the max depth, ie the number of hops
140  * to the furthest leaf.  Computing the max hop count breaks down into
141  * two cases: either the path goes through this node, in which case
142  * the hop count is the sum of the two biggest child depths plus 2.
143  * Or it could be the case that the max hop path is entirely
144  * containted in a child tree, in which case the max hop count is just
145  * the max hop count of this child.
146  */
147 static void update_hop_count(struct fw_node *node)
148 {
149 	int depths[2] = { -1, -1 };
150 	int max_child_hops = 0;
151 	int i;
152 
153 	for (i = 0; i < node->port_count; i++) {
154 		if (node->ports[i] == NULL)
155 			continue;
156 
157 		if (node->ports[i]->max_hops > max_child_hops)
158 			max_child_hops = node->ports[i]->max_hops;
159 
160 		if (node->ports[i]->max_depth > depths[0]) {
161 			depths[1] = depths[0];
162 			depths[0] = node->ports[i]->max_depth;
163 		} else if (node->ports[i]->max_depth > depths[1])
164 			depths[1] = node->ports[i]->max_depth;
165 	}
166 
167 	node->max_depth = depths[0] + 1;
168 	node->max_hops = max(max_child_hops, depths[0] + depths[1] + 2);
169 }
170 
171 static inline struct fw_node *fw_node(struct list_head *l)
172 {
173 	return list_entry(l, struct fw_node, link);
174 }
175 
176 /*
177  * This function builds the tree representation of the topology given
178  * by the self IDs from the latest bus reset.  During the construction
179  * of the tree, the function checks that the self IDs are valid and
180  * internally consistent.  On success this function returns the
181  * fw_node corresponding to the local card otherwise NULL.
182  */
183 static struct fw_node *build_tree(struct fw_card *card,
184 				  u32 *sid, int self_id_count)
185 {
186 	struct fw_node *node, *child, *local_node, *irm_node;
187 	struct list_head stack, *h;
188 	u32 *next_sid, *end, q;
189 	int i, port_count, child_port_count, phy_id, parent_count, stack_depth;
190 	int gap_count;
191 	bool beta_repeaters_present;
192 
193 	local_node = NULL;
194 	node = NULL;
195 	INIT_LIST_HEAD(&stack);
196 	stack_depth = 0;
197 	end = sid + self_id_count;
198 	phy_id = 0;
199 	irm_node = NULL;
200 	gap_count = SELF_ID_GAP_COUNT(*sid);
201 	beta_repeaters_present = false;
202 
203 	while (sid < end) {
204 		next_sid = count_ports(sid, &port_count, &child_port_count);
205 
206 		if (next_sid == NULL) {
207 			fw_err(card, "inconsistent extended self IDs\n");
208 			return NULL;
209 		}
210 
211 		q = *sid;
212 		if (phy_id != SELF_ID_PHY_ID(q)) {
213 			fw_err(card, "PHY ID mismatch in self ID: %d != %d\n",
214 			       phy_id, SELF_ID_PHY_ID(q));
215 			return NULL;
216 		}
217 
218 		if (child_port_count > stack_depth) {
219 			fw_err(card, "topology stack underflow\n");
220 			return NULL;
221 		}
222 
223 		/*
224 		 * Seek back from the top of our stack to find the
225 		 * start of the child nodes for this node.
226 		 */
227 		for (i = 0, h = &stack; i < child_port_count; i++)
228 			h = h->prev;
229 		/*
230 		 * When the stack is empty, this yields an invalid value,
231 		 * but that pointer will never be dereferenced.
232 		 */
233 		child = fw_node(h);
234 
235 		node = fw_node_create(q, port_count, card->color);
236 		if (node == NULL) {
237 			fw_err(card, "out of memory while building topology\n");
238 			return NULL;
239 		}
240 
241 		if (phy_id == (card->node_id & 0x3f))
242 			local_node = node;
243 
244 		if (SELF_ID_CONTENDER(q))
245 			irm_node = node;
246 
247 		parent_count = 0;
248 
249 		for (i = 0; i < port_count; i++) {
250 			switch (get_port_type(sid, i)) {
251 			case SELFID_PORT_PARENT:
252 				/*
253 				 * Who's your daddy?  We dont know the
254 				 * parent node at this time, so we
255 				 * temporarily abuse node->color for
256 				 * remembering the entry in the
257 				 * node->ports array where the parent
258 				 * node should be.  Later, when we
259 				 * handle the parent node, we fix up
260 				 * the reference.
261 				 */
262 				parent_count++;
263 				node->color = i;
264 				break;
265 
266 			case SELFID_PORT_CHILD:
267 				node->ports[i] = child;
268 				/*
269 				 * Fix up parent reference for this
270 				 * child node.
271 				 */
272 				child->ports[child->color] = node;
273 				child->color = card->color;
274 				child = fw_node(child->link.next);
275 				break;
276 			}
277 		}
278 
279 		/*
280 		 * Check that the node reports exactly one parent
281 		 * port, except for the root, which of course should
282 		 * have no parents.
283 		 */
284 		if ((next_sid == end && parent_count != 0) ||
285 		    (next_sid < end && parent_count != 1)) {
286 			fw_err(card, "parent port inconsistency for node %d: "
287 			       "parent_count=%d\n", phy_id, parent_count);
288 			return NULL;
289 		}
290 
291 		/* Pop the child nodes off the stack and push the new node. */
292 		__list_del(h->prev, &stack);
293 		list_add_tail(&node->link, &stack);
294 		stack_depth += 1 - child_port_count;
295 
296 		if (node->phy_speed == SCODE_BETA &&
297 		    parent_count + child_port_count > 1)
298 			beta_repeaters_present = true;
299 
300 		/*
301 		 * If PHYs report different gap counts, set an invalid count
302 		 * which will force a gap count reconfiguration and a reset.
303 		 */
304 		if (SELF_ID_GAP_COUNT(q) != gap_count)
305 			gap_count = 0;
306 
307 		update_hop_count(node);
308 
309 		sid = next_sid;
310 		phy_id++;
311 	}
312 
313 	card->root_node = node;
314 	card->irm_node = irm_node;
315 	card->gap_count = gap_count;
316 	card->beta_repeaters_present = beta_repeaters_present;
317 
318 	return local_node;
319 }
320 
321 typedef void (*fw_node_callback_t)(struct fw_card * card,
322 				   struct fw_node * node,
323 				   struct fw_node * parent);
324 
325 static void for_each_fw_node(struct fw_card *card, struct fw_node *root,
326 			     fw_node_callback_t callback)
327 {
328 	struct list_head list;
329 	struct fw_node *node, *next, *child, *parent;
330 	int i;
331 
332 	INIT_LIST_HEAD(&list);
333 
334 	fw_node_get(root);
335 	list_add_tail(&root->link, &list);
336 	parent = NULL;
337 	list_for_each_entry(node, &list, link) {
338 		node->color = card->color;
339 
340 		for (i = 0; i < node->port_count; i++) {
341 			child = node->ports[i];
342 			if (!child)
343 				continue;
344 			if (child->color == card->color)
345 				parent = child;
346 			else {
347 				fw_node_get(child);
348 				list_add_tail(&child->link, &list);
349 			}
350 		}
351 
352 		callback(card, node, parent);
353 	}
354 
355 	list_for_each_entry_safe(node, next, &list, link)
356 		fw_node_put(node);
357 }
358 
359 static void report_lost_node(struct fw_card *card,
360 			     struct fw_node *node, struct fw_node *parent)
361 {
362 	fw_node_event(card, node, FW_NODE_DESTROYED);
363 	fw_node_put(node);
364 
365 	/* Topology has changed - reset bus manager retry counter */
366 	card->bm_retries = 0;
367 }
368 
369 static void report_found_node(struct fw_card *card,
370 			      struct fw_node *node, struct fw_node *parent)
371 {
372 	int b_path = (node->phy_speed == SCODE_BETA);
373 
374 	if (parent != NULL) {
375 		/* min() macro doesn't work here with gcc 3.4 */
376 		node->max_speed = parent->max_speed < node->phy_speed ?
377 					parent->max_speed : node->phy_speed;
378 		node->b_path = parent->b_path && b_path;
379 	} else {
380 		node->max_speed = node->phy_speed;
381 		node->b_path = b_path;
382 	}
383 
384 	fw_node_event(card, node, FW_NODE_CREATED);
385 
386 	/* Topology has changed - reset bus manager retry counter */
387 	card->bm_retries = 0;
388 }
389 
390 void fw_destroy_nodes(struct fw_card *card)
391 {
392 	unsigned long flags;
393 
394 	spin_lock_irqsave(&card->lock, flags);
395 	card->color++;
396 	if (card->local_node != NULL)
397 		for_each_fw_node(card, card->local_node, report_lost_node);
398 	card->local_node = NULL;
399 	spin_unlock_irqrestore(&card->lock, flags);
400 }
401 
402 static void move_tree(struct fw_node *node0, struct fw_node *node1, int port)
403 {
404 	struct fw_node *tree;
405 	int i;
406 
407 	tree = node1->ports[port];
408 	node0->ports[port] = tree;
409 	for (i = 0; i < tree->port_count; i++) {
410 		if (tree->ports[i] == node1) {
411 			tree->ports[i] = node0;
412 			break;
413 		}
414 	}
415 }
416 
417 /*
418  * Compare the old topology tree for card with the new one specified by root.
419  * Queue the nodes and mark them as either found, lost or updated.
420  * Update the nodes in the card topology tree as we go.
421  */
422 static void update_tree(struct fw_card *card, struct fw_node *root)
423 {
424 	struct list_head list0, list1;
425 	struct fw_node *node0, *node1, *next1;
426 	int i, event;
427 
428 	INIT_LIST_HEAD(&list0);
429 	list_add_tail(&card->local_node->link, &list0);
430 	INIT_LIST_HEAD(&list1);
431 	list_add_tail(&root->link, &list1);
432 
433 	node0 = fw_node(list0.next);
434 	node1 = fw_node(list1.next);
435 
436 	while (&node0->link != &list0) {
437 		WARN_ON(node0->port_count != node1->port_count);
438 
439 		if (node0->link_on && !node1->link_on)
440 			event = FW_NODE_LINK_OFF;
441 		else if (!node0->link_on && node1->link_on)
442 			event = FW_NODE_LINK_ON;
443 		else if (node1->initiated_reset && node1->link_on)
444 			event = FW_NODE_INITIATED_RESET;
445 		else
446 			event = FW_NODE_UPDATED;
447 
448 		node0->node_id = node1->node_id;
449 		node0->color = card->color;
450 		node0->link_on = node1->link_on;
451 		node0->initiated_reset = node1->initiated_reset;
452 		node0->max_hops = node1->max_hops;
453 		node1->color = card->color;
454 		fw_node_event(card, node0, event);
455 
456 		if (card->root_node == node1)
457 			card->root_node = node0;
458 		if (card->irm_node == node1)
459 			card->irm_node = node0;
460 
461 		for (i = 0; i < node0->port_count; i++) {
462 			if (node0->ports[i] && node1->ports[i]) {
463 				/*
464 				 * This port didn't change, queue the
465 				 * connected node for further
466 				 * investigation.
467 				 */
468 				if (node0->ports[i]->color == card->color)
469 					continue;
470 				list_add_tail(&node0->ports[i]->link, &list0);
471 				list_add_tail(&node1->ports[i]->link, &list1);
472 			} else if (node0->ports[i]) {
473 				/*
474 				 * The nodes connected here were
475 				 * unplugged; unref the lost nodes and
476 				 * queue FW_NODE_LOST callbacks for
477 				 * them.
478 				 */
479 
480 				for_each_fw_node(card, node0->ports[i],
481 						 report_lost_node);
482 				node0->ports[i] = NULL;
483 			} else if (node1->ports[i]) {
484 				/*
485 				 * One or more node were connected to
486 				 * this port. Move the new nodes into
487 				 * the tree and queue FW_NODE_CREATED
488 				 * callbacks for them.
489 				 */
490 				move_tree(node0, node1, i);
491 				for_each_fw_node(card, node0->ports[i],
492 						 report_found_node);
493 			}
494 		}
495 
496 		node0 = fw_node(node0->link.next);
497 		next1 = fw_node(node1->link.next);
498 		fw_node_put(node1);
499 		node1 = next1;
500 	}
501 }
502 
503 static void update_topology_map(struct fw_card *card,
504 				u32 *self_ids, int self_id_count)
505 {
506 	int node_count = (card->root_node->node_id & 0x3f) + 1;
507 	__be32 *map = card->topology_map;
508 
509 	*map++ = cpu_to_be32((self_id_count + 2) << 16);
510 	*map++ = cpu_to_be32(be32_to_cpu(card->topology_map[1]) + 1);
511 	*map++ = cpu_to_be32((node_count << 16) | self_id_count);
512 
513 	while (self_id_count--)
514 		*map++ = cpu_to_be32p(self_ids++);
515 
516 	fw_compute_block_crc(card->topology_map);
517 }
518 
519 void fw_core_handle_bus_reset(struct fw_card *card, int node_id, int generation,
520 			      int self_id_count, u32 *self_ids, bool bm_abdicate)
521 {
522 	struct fw_node *local_node;
523 	unsigned long flags;
524 
525 	/*
526 	 * If the selfID buffer is not the immediate successor of the
527 	 * previously processed one, we cannot reliably compare the
528 	 * old and new topologies.
529 	 */
530 	if (!is_next_generation(generation, card->generation) &&
531 	    card->local_node != NULL) {
532 		fw_destroy_nodes(card);
533 		card->bm_retries = 0;
534 	}
535 
536 	spin_lock_irqsave(&card->lock, flags);
537 
538 	card->broadcast_channel_allocated = card->broadcast_channel_auto_allocated;
539 	card->node_id = node_id;
540 	/*
541 	 * Update node_id before generation to prevent anybody from using
542 	 * a stale node_id together with a current generation.
543 	 */
544 	smp_wmb();
545 	card->generation = generation;
546 	card->reset_jiffies = get_jiffies_64();
547 	card->bm_node_id  = 0xffff;
548 	card->bm_abdicate = bm_abdicate;
549 	fw_schedule_bm_work(card, 0);
550 
551 	local_node = build_tree(card, self_ids, self_id_count);
552 
553 	update_topology_map(card, self_ids, self_id_count);
554 
555 	card->color++;
556 
557 	if (local_node == NULL) {
558 		fw_err(card, "topology build failed\n");
559 		/* FIXME: We need to issue a bus reset in this case. */
560 	} else if (card->local_node == NULL) {
561 		card->local_node = local_node;
562 		for_each_fw_node(card, local_node, report_found_node);
563 	} else {
564 		update_tree(card, local_node);
565 	}
566 
567 	spin_unlock_irqrestore(&card->lock, flags);
568 }
569 EXPORT_SYMBOL(fw_core_handle_bus_reset);
570