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