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