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(struct_size(node, ports, port_count), GFP_ATOMIC);
116 	if (node == NULL)
117 		return NULL;
118 
119 	node->color = color;
120 	node->node_id = LOCAL_BUS | SELF_ID_PHY_ID(sid);
121 	node->link_on = SELF_ID_LINK_ON(sid);
122 	node->phy_speed = SELF_ID_PHY_SPEED(sid);
123 	node->initiated_reset = SELF_ID_PHY_INITIATOR(sid);
124 	node->port_count = port_count;
125 
126 	refcount_set(&node->ref_count, 1);
127 	INIT_LIST_HEAD(&node->link);
128 
129 	return node;
130 }
131 
132 /*
133  * Compute the maximum hop count for this node and it's children.  The
134  * maximum hop count is the maximum number of connections between any
135  * two nodes in the subtree rooted at this node.  We need this for
136  * setting the gap count.  As we build the tree bottom up in
137  * build_tree() below, this is fairly easy to do: for each node we
138  * maintain the max hop count and the max depth, ie the number of hops
139  * to the furthest leaf.  Computing the max hop count breaks down into
140  * two cases: either the path goes through this node, in which case
141  * the hop count is the sum of the two biggest child depths plus 2.
142  * Or it could be the case that the max hop path is entirely
143  * containted in a child tree, in which case the max hop count is just
144  * the max hop count of this child.
145  */
146 static void update_hop_count(struct fw_node *node)
147 {
148 	int depths[2] = { -1, -1 };
149 	int max_child_hops = 0;
150 	int i;
151 
152 	for (i = 0; i < node->port_count; i++) {
153 		if (node->ports[i] == NULL)
154 			continue;
155 
156 		if (node->ports[i]->max_hops > max_child_hops)
157 			max_child_hops = node->ports[i]->max_hops;
158 
159 		if (node->ports[i]->max_depth > depths[0]) {
160 			depths[1] = depths[0];
161 			depths[0] = node->ports[i]->max_depth;
162 		} else if (node->ports[i]->max_depth > depths[1])
163 			depths[1] = node->ports[i]->max_depth;
164 	}
165 
166 	node->max_depth = depths[0] + 1;
167 	node->max_hops = max(max_child_hops, depths[0] + depths[1] + 2);
168 }
169 
170 static inline struct fw_node *fw_node(struct list_head *l)
171 {
172 	return list_entry(l, struct fw_node, link);
173 }
174 
175 /*
176  * This function builds the tree representation of the topology given
177  * by the self IDs from the latest bus reset.  During the construction
178  * of the tree, the function checks that the self IDs are valid and
179  * internally consistent.  On success this function returns the
180  * fw_node corresponding to the local card otherwise NULL.
181  */
182 static struct fw_node *build_tree(struct fw_card *card,
183 				  u32 *sid, int self_id_count)
184 {
185 	struct fw_node *node, *child, *local_node, *irm_node;
186 	struct list_head stack, *h;
187 	u32 *next_sid, *end, q;
188 	int i, port_count, child_port_count, phy_id, parent_count, stack_depth;
189 	int gap_count;
190 	bool beta_repeaters_present;
191 
192 	local_node = NULL;
193 	node = NULL;
194 	INIT_LIST_HEAD(&stack);
195 	stack_depth = 0;
196 	end = sid + self_id_count;
197 	phy_id = 0;
198 	irm_node = NULL;
199 	gap_count = SELF_ID_GAP_COUNT(*sid);
200 	beta_repeaters_present = false;
201 
202 	while (sid < end) {
203 		next_sid = count_ports(sid, &port_count, &child_port_count);
204 
205 		if (next_sid == NULL) {
206 			fw_err(card, "inconsistent extended self IDs\n");
207 			return NULL;
208 		}
209 
210 		q = *sid;
211 		if (phy_id != SELF_ID_PHY_ID(q)) {
212 			fw_err(card, "PHY ID mismatch in self ID: %d != %d\n",
213 			       phy_id, SELF_ID_PHY_ID(q));
214 			return NULL;
215 		}
216 
217 		if (child_port_count > stack_depth) {
218 			fw_err(card, "topology stack underflow\n");
219 			return NULL;
220 		}
221 
222 		/*
223 		 * Seek back from the top of our stack to find the
224 		 * start of the child nodes for this node.
225 		 */
226 		for (i = 0, h = &stack; i < child_port_count; i++)
227 			h = h->prev;
228 		/*
229 		 * When the stack is empty, this yields an invalid value,
230 		 * but that pointer will never be dereferenced.
231 		 */
232 		child = fw_node(h);
233 
234 		node = fw_node_create(q, port_count, card->color);
235 		if (node == NULL) {
236 			fw_err(card, "out of memory while building topology\n");
237 			return NULL;
238 		}
239 
240 		if (phy_id == (card->node_id & 0x3f))
241 			local_node = node;
242 
243 		if (SELF_ID_CONTENDER(q))
244 			irm_node = node;
245 
246 		parent_count = 0;
247 
248 		for (i = 0; i < port_count; i++) {
249 			switch (get_port_type(sid, i)) {
250 			case SELFID_PORT_PARENT:
251 				/*
252 				 * Who's your daddy?  We dont know the
253 				 * parent node at this time, so we
254 				 * temporarily abuse node->color for
255 				 * remembering the entry in the
256 				 * node->ports array where the parent
257 				 * node should be.  Later, when we
258 				 * handle the parent node, we fix up
259 				 * the reference.
260 				 */
261 				parent_count++;
262 				node->color = i;
263 				break;
264 
265 			case SELFID_PORT_CHILD:
266 				node->ports[i] = child;
267 				/*
268 				 * Fix up parent reference for this
269 				 * child node.
270 				 */
271 				child->ports[child->color] = node;
272 				child->color = card->color;
273 				child = fw_node(child->link.next);
274 				break;
275 			}
276 		}
277 
278 		/*
279 		 * Check that the node reports exactly one parent
280 		 * port, except for the root, which of course should
281 		 * have no parents.
282 		 */
283 		if ((next_sid == end && parent_count != 0) ||
284 		    (next_sid < end && parent_count != 1)) {
285 			fw_err(card, "parent port inconsistency for node %d: "
286 			       "parent_count=%d\n", phy_id, parent_count);
287 			return NULL;
288 		}
289 
290 		/* Pop the child nodes off the stack and push the new node. */
291 		__list_del(h->prev, &stack);
292 		list_add_tail(&node->link, &stack);
293 		stack_depth += 1 - child_port_count;
294 
295 		if (node->phy_speed == SCODE_BETA &&
296 		    parent_count + child_port_count > 1)
297 			beta_repeaters_present = true;
298 
299 		/*
300 		 * If PHYs report different gap counts, set an invalid count
301 		 * which will force a gap count reconfiguration and a reset.
302 		 */
303 		if (SELF_ID_GAP_COUNT(q) != gap_count)
304 			gap_count = 0;
305 
306 		update_hop_count(node);
307 
308 		sid = next_sid;
309 		phy_id++;
310 	}
311 
312 	card->root_node = node;
313 	card->irm_node = irm_node;
314 	card->gap_count = gap_count;
315 	card->beta_repeaters_present = beta_repeaters_present;
316 
317 	return local_node;
318 }
319 
320 typedef void (*fw_node_callback_t)(struct fw_card * card,
321 				   struct fw_node * node,
322 				   struct fw_node * parent);
323 
324 static void for_each_fw_node(struct fw_card *card, struct fw_node *root,
325 			     fw_node_callback_t callback)
326 {
327 	struct list_head list;
328 	struct fw_node *node, *next, *child, *parent;
329 	int i;
330 
331 	INIT_LIST_HEAD(&list);
332 
333 	fw_node_get(root);
334 	list_add_tail(&root->link, &list);
335 	parent = NULL;
336 	list_for_each_entry(node, &list, link) {
337 		node->color = card->color;
338 
339 		for (i = 0; i < node->port_count; i++) {
340 			child = node->ports[i];
341 			if (!child)
342 				continue;
343 			if (child->color == card->color)
344 				parent = child;
345 			else {
346 				fw_node_get(child);
347 				list_add_tail(&child->link, &list);
348 			}
349 		}
350 
351 		callback(card, node, parent);
352 	}
353 
354 	list_for_each_entry_safe(node, next, &list, link)
355 		fw_node_put(node);
356 }
357 
358 static void report_lost_node(struct fw_card *card,
359 			     struct fw_node *node, struct fw_node *parent)
360 {
361 	fw_node_event(card, node, FW_NODE_DESTROYED);
362 	fw_node_put(node);
363 
364 	/* Topology has changed - reset bus manager retry counter */
365 	card->bm_retries = 0;
366 }
367 
368 static void report_found_node(struct fw_card *card,
369 			      struct fw_node *node, struct fw_node *parent)
370 {
371 	int b_path = (node->phy_speed == SCODE_BETA);
372 
373 	if (parent != NULL) {
374 		/* min() macro doesn't work here with gcc 3.4 */
375 		node->max_speed = parent->max_speed < node->phy_speed ?
376 					parent->max_speed : node->phy_speed;
377 		node->b_path = parent->b_path && b_path;
378 	} else {
379 		node->max_speed = node->phy_speed;
380 		node->b_path = b_path;
381 	}
382 
383 	fw_node_event(card, node, FW_NODE_CREATED);
384 
385 	/* Topology has changed - reset bus manager retry counter */
386 	card->bm_retries = 0;
387 }
388 
389 void fw_destroy_nodes(struct fw_card *card)
390 {
391 	unsigned long flags;
392 
393 	spin_lock_irqsave(&card->lock, flags);
394 	card->color++;
395 	if (card->local_node != NULL)
396 		for_each_fw_node(card, card->local_node, report_lost_node);
397 	card->local_node = NULL;
398 	spin_unlock_irqrestore(&card->lock, flags);
399 }
400 
401 static void move_tree(struct fw_node *node0, struct fw_node *node1, int port)
402 {
403 	struct fw_node *tree;
404 	int i;
405 
406 	tree = node1->ports[port];
407 	node0->ports[port] = tree;
408 	for (i = 0; i < tree->port_count; i++) {
409 		if (tree->ports[i] == node1) {
410 			tree->ports[i] = node0;
411 			break;
412 		}
413 	}
414 }
415 
416 /*
417  * Compare the old topology tree for card with the new one specified by root.
418  * Queue the nodes and mark them as either found, lost or updated.
419  * Update the nodes in the card topology tree as we go.
420  */
421 static void update_tree(struct fw_card *card, struct fw_node *root)
422 {
423 	struct list_head list0, list1;
424 	struct fw_node *node0, *node1, *next1;
425 	int i, event;
426 
427 	INIT_LIST_HEAD(&list0);
428 	list_add_tail(&card->local_node->link, &list0);
429 	INIT_LIST_HEAD(&list1);
430 	list_add_tail(&root->link, &list1);
431 
432 	node0 = fw_node(list0.next);
433 	node1 = fw_node(list1.next);
434 
435 	while (&node0->link != &list0) {
436 		WARN_ON(node0->port_count != node1->port_count);
437 
438 		if (node0->link_on && !node1->link_on)
439 			event = FW_NODE_LINK_OFF;
440 		else if (!node0->link_on && node1->link_on)
441 			event = FW_NODE_LINK_ON;
442 		else if (node1->initiated_reset && node1->link_on)
443 			event = FW_NODE_INITIATED_RESET;
444 		else
445 			event = FW_NODE_UPDATED;
446 
447 		node0->node_id = node1->node_id;
448 		node0->color = card->color;
449 		node0->link_on = node1->link_on;
450 		node0->initiated_reset = node1->initiated_reset;
451 		node0->max_hops = node1->max_hops;
452 		node1->color = card->color;
453 		fw_node_event(card, node0, event);
454 
455 		if (card->root_node == node1)
456 			card->root_node = node0;
457 		if (card->irm_node == node1)
458 			card->irm_node = node0;
459 
460 		for (i = 0; i < node0->port_count; i++) {
461 			if (node0->ports[i] && node1->ports[i]) {
462 				/*
463 				 * This port didn't change, queue the
464 				 * connected node for further
465 				 * investigation.
466 				 */
467 				if (node0->ports[i]->color == card->color)
468 					continue;
469 				list_add_tail(&node0->ports[i]->link, &list0);
470 				list_add_tail(&node1->ports[i]->link, &list1);
471 			} else if (node0->ports[i]) {
472 				/*
473 				 * The nodes connected here were
474 				 * unplugged; unref the lost nodes and
475 				 * queue FW_NODE_LOST callbacks for
476 				 * them.
477 				 */
478 
479 				for_each_fw_node(card, node0->ports[i],
480 						 report_lost_node);
481 				node0->ports[i] = NULL;
482 			} else if (node1->ports[i]) {
483 				/*
484 				 * One or more node were connected to
485 				 * this port. Move the new nodes into
486 				 * the tree and queue FW_NODE_CREATED
487 				 * callbacks for them.
488 				 */
489 				move_tree(node0, node1, i);
490 				for_each_fw_node(card, node0->ports[i],
491 						 report_found_node);
492 			}
493 		}
494 
495 		node0 = fw_node(node0->link.next);
496 		next1 = fw_node(node1->link.next);
497 		fw_node_put(node1);
498 		node1 = next1;
499 	}
500 }
501 
502 static void update_topology_map(struct fw_card *card,
503 				u32 *self_ids, int self_id_count)
504 {
505 	int node_count = (card->root_node->node_id & 0x3f) + 1;
506 	__be32 *map = card->topology_map;
507 
508 	*map++ = cpu_to_be32((self_id_count + 2) << 16);
509 	*map++ = cpu_to_be32(be32_to_cpu(card->topology_map[1]) + 1);
510 	*map++ = cpu_to_be32((node_count << 16) | self_id_count);
511 
512 	while (self_id_count--)
513 		*map++ = cpu_to_be32p(self_ids++);
514 
515 	fw_compute_block_crc(card->topology_map);
516 }
517 
518 void fw_core_handle_bus_reset(struct fw_card *card, int node_id, int generation,
519 			      int self_id_count, u32 *self_ids, bool bm_abdicate)
520 {
521 	struct fw_node *local_node;
522 	unsigned long flags;
523 
524 	/*
525 	 * If the selfID buffer is not the immediate successor of the
526 	 * previously processed one, we cannot reliably compare the
527 	 * old and new topologies.
528 	 */
529 	if (!is_next_generation(generation, card->generation) &&
530 	    card->local_node != NULL) {
531 		fw_destroy_nodes(card);
532 		card->bm_retries = 0;
533 	}
534 
535 	spin_lock_irqsave(&card->lock, flags);
536 
537 	card->broadcast_channel_allocated = card->broadcast_channel_auto_allocated;
538 	card->node_id = node_id;
539 	/*
540 	 * Update node_id before generation to prevent anybody from using
541 	 * a stale node_id together with a current generation.
542 	 */
543 	smp_wmb();
544 	card->generation = generation;
545 	card->reset_jiffies = get_jiffies_64();
546 	card->bm_node_id  = 0xffff;
547 	card->bm_abdicate = bm_abdicate;
548 	fw_schedule_bm_work(card, 0);
549 
550 	local_node = build_tree(card, self_ids, self_id_count);
551 
552 	update_topology_map(card, self_ids, self_id_count);
553 
554 	card->color++;
555 
556 	if (local_node == NULL) {
557 		fw_err(card, "topology build failed\n");
558 		/* FIXME: We need to issue a bus reset in this case. */
559 	} else if (card->local_node == NULL) {
560 		card->local_node = local_node;
561 		for_each_fw_node(card, local_node, report_found_node);
562 	} else {
563 		update_tree(card, local_node);
564 	}
565 
566 	spin_unlock_irqrestore(&card->lock, flags);
567 }
568 EXPORT_SYMBOL(fw_core_handle_bus_reset);
569