xref: /linux/drivers/thunderbolt/tunnel.c (revision 24168c5e6dfbdd5b414f048f47f75d64533296ca)
1 // SPDX-License-Identifier: GPL-2.0
2 /*
3  * Thunderbolt driver - Tunneling support
4  *
5  * Copyright (c) 2014 Andreas Noever <andreas.noever@gmail.com>
6  * Copyright (C) 2019, Intel Corporation
7  */
8 
9 #include <linux/delay.h>
10 #include <linux/slab.h>
11 #include <linux/list.h>
12 #include <linux/ktime.h>
13 #include <linux/string_helpers.h>
14 
15 #include "tunnel.h"
16 #include "tb.h"
17 
18 /* PCIe adapters use always HopID of 8 for both directions */
19 #define TB_PCI_HOPID			8
20 
21 #define TB_PCI_PATH_DOWN		0
22 #define TB_PCI_PATH_UP			1
23 
24 #define TB_PCI_PRIORITY			3
25 #define TB_PCI_WEIGHT			1
26 
27 /* USB3 adapters use always HopID of 8 for both directions */
28 #define TB_USB3_HOPID			8
29 
30 #define TB_USB3_PATH_DOWN		0
31 #define TB_USB3_PATH_UP			1
32 
33 #define TB_USB3_PRIORITY		3
34 #define TB_USB3_WEIGHT			2
35 
36 /* DP adapters use HopID 8 for AUX and 9 for Video */
37 #define TB_DP_AUX_TX_HOPID		8
38 #define TB_DP_AUX_RX_HOPID		8
39 #define TB_DP_VIDEO_HOPID		9
40 
41 #define TB_DP_VIDEO_PATH_OUT		0
42 #define TB_DP_AUX_PATH_OUT		1
43 #define TB_DP_AUX_PATH_IN		2
44 
45 #define TB_DP_VIDEO_PRIORITY		1
46 #define TB_DP_VIDEO_WEIGHT		1
47 
48 #define TB_DP_AUX_PRIORITY		2
49 #define TB_DP_AUX_WEIGHT		1
50 
51 /* Minimum number of credits needed for PCIe path */
52 #define TB_MIN_PCIE_CREDITS		6U
53 /*
54  * Number of credits we try to allocate for each DMA path if not limited
55  * by the host router baMaxHI.
56  */
57 #define TB_DMA_CREDITS			14
58 /* Minimum number of credits for DMA path */
59 #define TB_MIN_DMA_CREDITS		1
60 
61 #define TB_DMA_PRIORITY			5
62 #define TB_DMA_WEIGHT			1
63 
64 /*
65  * Reserve additional bandwidth for USB 3.x and PCIe bulk traffic
66  * according to USB4 v2 Connection Manager guide. This ends up reserving
67  * 1500 Mb/s for PCIe and 3000 Mb/s for USB 3.x taking weights into
68  * account.
69  */
70 #define USB4_V2_PCI_MIN_BANDWIDTH	(1500 * TB_PCI_WEIGHT)
71 #define USB4_V2_USB3_MIN_BANDWIDTH	(1500 * TB_USB3_WEIGHT)
72 
73 static unsigned int dma_credits = TB_DMA_CREDITS;
74 module_param(dma_credits, uint, 0444);
75 MODULE_PARM_DESC(dma_credits, "specify custom credits for DMA tunnels (default: "
76                 __MODULE_STRING(TB_DMA_CREDITS) ")");
77 
78 static bool bw_alloc_mode = true;
79 module_param(bw_alloc_mode, bool, 0444);
80 MODULE_PARM_DESC(bw_alloc_mode,
81 		 "enable bandwidth allocation mode if supported (default: true)");
82 
83 static const char * const tb_tunnel_names[] = { "PCI", "DP", "DMA", "USB3" };
84 
85 static inline unsigned int tb_usable_credits(const struct tb_port *port)
86 {
87 	return port->total_credits - port->ctl_credits;
88 }
89 
90 /**
91  * tb_available_credits() - Available credits for PCIe and DMA
92  * @port: Lane adapter to check
93  * @max_dp_streams: If non-%NULL stores maximum number of simultaneous DP
94  *		    streams possible through this lane adapter
95  */
96 static unsigned int tb_available_credits(const struct tb_port *port,
97 					 size_t *max_dp_streams)
98 {
99 	const struct tb_switch *sw = port->sw;
100 	int credits, usb3, pcie, spare;
101 	size_t ndp;
102 
103 	usb3 = tb_acpi_may_tunnel_usb3() ? sw->max_usb3_credits : 0;
104 	pcie = tb_acpi_may_tunnel_pcie() ? sw->max_pcie_credits : 0;
105 
106 	if (tb_acpi_is_xdomain_allowed()) {
107 		spare = min_not_zero(sw->max_dma_credits, dma_credits);
108 		/* Add some credits for potential second DMA tunnel */
109 		spare += TB_MIN_DMA_CREDITS;
110 	} else {
111 		spare = 0;
112 	}
113 
114 	credits = tb_usable_credits(port);
115 	if (tb_acpi_may_tunnel_dp()) {
116 		/*
117 		 * Maximum number of DP streams possible through the
118 		 * lane adapter.
119 		 */
120 		if (sw->min_dp_aux_credits + sw->min_dp_main_credits)
121 			ndp = (credits - (usb3 + pcie + spare)) /
122 			      (sw->min_dp_aux_credits + sw->min_dp_main_credits);
123 		else
124 			ndp = 0;
125 	} else {
126 		ndp = 0;
127 	}
128 	credits -= ndp * (sw->min_dp_aux_credits + sw->min_dp_main_credits);
129 	credits -= usb3;
130 
131 	if (max_dp_streams)
132 		*max_dp_streams = ndp;
133 
134 	return credits > 0 ? credits : 0;
135 }
136 
137 static void tb_init_pm_support(struct tb_path_hop *hop)
138 {
139 	struct tb_port *out_port = hop->out_port;
140 	struct tb_port *in_port = hop->in_port;
141 
142 	if (tb_port_is_null(in_port) && tb_port_is_null(out_port) &&
143 	    usb4_switch_version(in_port->sw) >= 2)
144 		hop->pm_support = true;
145 }
146 
147 static struct tb_tunnel *tb_tunnel_alloc(struct tb *tb, size_t npaths,
148 					 enum tb_tunnel_type type)
149 {
150 	struct tb_tunnel *tunnel;
151 
152 	tunnel = kzalloc(sizeof(*tunnel), GFP_KERNEL);
153 	if (!tunnel)
154 		return NULL;
155 
156 	tunnel->paths = kcalloc(npaths, sizeof(tunnel->paths[0]), GFP_KERNEL);
157 	if (!tunnel->paths) {
158 		tb_tunnel_free(tunnel);
159 		return NULL;
160 	}
161 
162 	INIT_LIST_HEAD(&tunnel->list);
163 	tunnel->tb = tb;
164 	tunnel->npaths = npaths;
165 	tunnel->type = type;
166 
167 	return tunnel;
168 }
169 
170 static int tb_pci_set_ext_encapsulation(struct tb_tunnel *tunnel, bool enable)
171 {
172 	struct tb_port *port = tb_upstream_port(tunnel->dst_port->sw);
173 	int ret;
174 
175 	/* Only supported of both routers are at least USB4 v2 */
176 	if ((usb4_switch_version(tunnel->src_port->sw) < 2) ||
177 	   (usb4_switch_version(tunnel->dst_port->sw) < 2))
178 		return 0;
179 
180 	if (enable && tb_port_get_link_generation(port) < 4)
181 		return 0;
182 
183 	ret = usb4_pci_port_set_ext_encapsulation(tunnel->src_port, enable);
184 	if (ret)
185 		return ret;
186 
187 	/*
188 	 * Downstream router could be unplugged so disable of encapsulation
189 	 * in upstream router is still possible.
190 	 */
191 	ret = usb4_pci_port_set_ext_encapsulation(tunnel->dst_port, enable);
192 	if (ret) {
193 		if (enable)
194 			return ret;
195 		if (ret != -ENODEV)
196 			return ret;
197 	}
198 
199 	tb_tunnel_dbg(tunnel, "extended encapsulation %s\n",
200 		      str_enabled_disabled(enable));
201 	return 0;
202 }
203 
204 static int tb_pci_activate(struct tb_tunnel *tunnel, bool activate)
205 {
206 	int res;
207 
208 	if (activate) {
209 		res = tb_pci_set_ext_encapsulation(tunnel, activate);
210 		if (res)
211 			return res;
212 	}
213 
214 	if (activate)
215 		res = tb_pci_port_enable(tunnel->dst_port, activate);
216 	else
217 		res = tb_pci_port_enable(tunnel->src_port, activate);
218 	if (res)
219 		return res;
220 
221 
222 	if (activate) {
223 		res = tb_pci_port_enable(tunnel->src_port, activate);
224 		if (res)
225 			return res;
226 	} else {
227 		/* Downstream router could be unplugged */
228 		tb_pci_port_enable(tunnel->dst_port, activate);
229 	}
230 
231 	return activate ? 0 : tb_pci_set_ext_encapsulation(tunnel, activate);
232 }
233 
234 static int tb_pci_init_credits(struct tb_path_hop *hop)
235 {
236 	struct tb_port *port = hop->in_port;
237 	struct tb_switch *sw = port->sw;
238 	unsigned int credits;
239 
240 	if (tb_port_use_credit_allocation(port)) {
241 		unsigned int available;
242 
243 		available = tb_available_credits(port, NULL);
244 		credits = min(sw->max_pcie_credits, available);
245 
246 		if (credits < TB_MIN_PCIE_CREDITS)
247 			return -ENOSPC;
248 
249 		credits = max(TB_MIN_PCIE_CREDITS, credits);
250 	} else {
251 		if (tb_port_is_null(port))
252 			credits = port->bonded ? 32 : 16;
253 		else
254 			credits = 7;
255 	}
256 
257 	hop->initial_credits = credits;
258 	return 0;
259 }
260 
261 static int tb_pci_init_path(struct tb_path *path)
262 {
263 	struct tb_path_hop *hop;
264 
265 	path->egress_fc_enable = TB_PATH_SOURCE | TB_PATH_INTERNAL;
266 	path->egress_shared_buffer = TB_PATH_NONE;
267 	path->ingress_fc_enable = TB_PATH_ALL;
268 	path->ingress_shared_buffer = TB_PATH_NONE;
269 	path->priority = TB_PCI_PRIORITY;
270 	path->weight = TB_PCI_WEIGHT;
271 	path->drop_packages = 0;
272 
273 	tb_path_for_each_hop(path, hop) {
274 		int ret;
275 
276 		ret = tb_pci_init_credits(hop);
277 		if (ret)
278 			return ret;
279 	}
280 
281 	return 0;
282 }
283 
284 /**
285  * tb_tunnel_discover_pci() - Discover existing PCIe tunnels
286  * @tb: Pointer to the domain structure
287  * @down: PCIe downstream adapter
288  * @alloc_hopid: Allocate HopIDs from visited ports
289  *
290  * If @down adapter is active, follows the tunnel to the PCIe upstream
291  * adapter and back. Returns the discovered tunnel or %NULL if there was
292  * no tunnel.
293  */
294 struct tb_tunnel *tb_tunnel_discover_pci(struct tb *tb, struct tb_port *down,
295 					 bool alloc_hopid)
296 {
297 	struct tb_tunnel *tunnel;
298 	struct tb_path *path;
299 
300 	if (!tb_pci_port_is_enabled(down))
301 		return NULL;
302 
303 	tunnel = tb_tunnel_alloc(tb, 2, TB_TUNNEL_PCI);
304 	if (!tunnel)
305 		return NULL;
306 
307 	tunnel->activate = tb_pci_activate;
308 	tunnel->src_port = down;
309 
310 	/*
311 	 * Discover both paths even if they are not complete. We will
312 	 * clean them up by calling tb_tunnel_deactivate() below in that
313 	 * case.
314 	 */
315 	path = tb_path_discover(down, TB_PCI_HOPID, NULL, -1,
316 				&tunnel->dst_port, "PCIe Up", alloc_hopid);
317 	if (!path) {
318 		/* Just disable the downstream port */
319 		tb_pci_port_enable(down, false);
320 		goto err_free;
321 	}
322 	tunnel->paths[TB_PCI_PATH_UP] = path;
323 	if (tb_pci_init_path(tunnel->paths[TB_PCI_PATH_UP]))
324 		goto err_free;
325 
326 	path = tb_path_discover(tunnel->dst_port, -1, down, TB_PCI_HOPID, NULL,
327 				"PCIe Down", alloc_hopid);
328 	if (!path)
329 		goto err_deactivate;
330 	tunnel->paths[TB_PCI_PATH_DOWN] = path;
331 	if (tb_pci_init_path(tunnel->paths[TB_PCI_PATH_DOWN]))
332 		goto err_deactivate;
333 
334 	/* Validate that the tunnel is complete */
335 	if (!tb_port_is_pcie_up(tunnel->dst_port)) {
336 		tb_port_warn(tunnel->dst_port,
337 			     "path does not end on a PCIe adapter, cleaning up\n");
338 		goto err_deactivate;
339 	}
340 
341 	if (down != tunnel->src_port) {
342 		tb_tunnel_warn(tunnel, "path is not complete, cleaning up\n");
343 		goto err_deactivate;
344 	}
345 
346 	if (!tb_pci_port_is_enabled(tunnel->dst_port)) {
347 		tb_tunnel_warn(tunnel,
348 			       "tunnel is not fully activated, cleaning up\n");
349 		goto err_deactivate;
350 	}
351 
352 	tb_tunnel_dbg(tunnel, "discovered\n");
353 	return tunnel;
354 
355 err_deactivate:
356 	tb_tunnel_deactivate(tunnel);
357 err_free:
358 	tb_tunnel_free(tunnel);
359 
360 	return NULL;
361 }
362 
363 /**
364  * tb_tunnel_alloc_pci() - allocate a pci tunnel
365  * @tb: Pointer to the domain structure
366  * @up: PCIe upstream adapter port
367  * @down: PCIe downstream adapter port
368  *
369  * Allocate a PCI tunnel. The ports must be of type TB_TYPE_PCIE_UP and
370  * TB_TYPE_PCIE_DOWN.
371  *
372  * Return: Returns a tb_tunnel on success or NULL on failure.
373  */
374 struct tb_tunnel *tb_tunnel_alloc_pci(struct tb *tb, struct tb_port *up,
375 				      struct tb_port *down)
376 {
377 	struct tb_tunnel *tunnel;
378 	struct tb_path *path;
379 
380 	tunnel = tb_tunnel_alloc(tb, 2, TB_TUNNEL_PCI);
381 	if (!tunnel)
382 		return NULL;
383 
384 	tunnel->activate = tb_pci_activate;
385 	tunnel->src_port = down;
386 	tunnel->dst_port = up;
387 
388 	path = tb_path_alloc(tb, down, TB_PCI_HOPID, up, TB_PCI_HOPID, 0,
389 			     "PCIe Down");
390 	if (!path)
391 		goto err_free;
392 	tunnel->paths[TB_PCI_PATH_DOWN] = path;
393 	if (tb_pci_init_path(path))
394 		goto err_free;
395 
396 	path = tb_path_alloc(tb, up, TB_PCI_HOPID, down, TB_PCI_HOPID, 0,
397 			     "PCIe Up");
398 	if (!path)
399 		goto err_free;
400 	tunnel->paths[TB_PCI_PATH_UP] = path;
401 	if (tb_pci_init_path(path))
402 		goto err_free;
403 
404 	return tunnel;
405 
406 err_free:
407 	tb_tunnel_free(tunnel);
408 	return NULL;
409 }
410 
411 /**
412  * tb_tunnel_reserved_pci() - Amount of bandwidth to reserve for PCIe
413  * @port: Lane 0 adapter
414  * @reserved_up: Upstream bandwidth in Mb/s to reserve
415  * @reserved_down: Downstream bandwidth in Mb/s to reserve
416  *
417  * Can be called to any connected lane 0 adapter to find out how much
418  * bandwidth needs to be left in reserve for possible PCIe bulk traffic.
419  * Returns true if there is something to be reserved and writes the
420  * amount to @reserved_down/@reserved_up. Otherwise returns false and
421  * does not touch the parameters.
422  */
423 bool tb_tunnel_reserved_pci(struct tb_port *port, int *reserved_up,
424 			    int *reserved_down)
425 {
426 	if (WARN_ON_ONCE(!port->remote))
427 		return false;
428 
429 	if (!tb_acpi_may_tunnel_pcie())
430 		return false;
431 
432 	if (tb_port_get_link_generation(port) < 4)
433 		return false;
434 
435 	/* Must have PCIe adapters */
436 	if (tb_is_upstream_port(port)) {
437 		if (!tb_switch_find_port(port->sw, TB_TYPE_PCIE_UP))
438 			return false;
439 		if (!tb_switch_find_port(port->remote->sw, TB_TYPE_PCIE_DOWN))
440 			return false;
441 	} else {
442 		if (!tb_switch_find_port(port->sw, TB_TYPE_PCIE_DOWN))
443 			return false;
444 		if (!tb_switch_find_port(port->remote->sw, TB_TYPE_PCIE_UP))
445 			return false;
446 	}
447 
448 	*reserved_up = USB4_V2_PCI_MIN_BANDWIDTH;
449 	*reserved_down = USB4_V2_PCI_MIN_BANDWIDTH;
450 
451 	tb_port_dbg(port, "reserving %u/%u Mb/s for PCIe\n", *reserved_up,
452 		    *reserved_down);
453 	return true;
454 }
455 
456 static bool tb_dp_is_usb4(const struct tb_switch *sw)
457 {
458 	/* Titan Ridge DP adapters need the same treatment as USB4 */
459 	return tb_switch_is_usb4(sw) || tb_switch_is_titan_ridge(sw);
460 }
461 
462 static int tb_dp_cm_handshake(struct tb_port *in, struct tb_port *out,
463 			      int timeout_msec)
464 {
465 	ktime_t timeout = ktime_add_ms(ktime_get(), timeout_msec);
466 	u32 val;
467 	int ret;
468 
469 	/* Both ends need to support this */
470 	if (!tb_dp_is_usb4(in->sw) || !tb_dp_is_usb4(out->sw))
471 		return 0;
472 
473 	ret = tb_port_read(out, &val, TB_CFG_PORT,
474 			   out->cap_adap + DP_STATUS_CTRL, 1);
475 	if (ret)
476 		return ret;
477 
478 	val |= DP_STATUS_CTRL_UF | DP_STATUS_CTRL_CMHS;
479 
480 	ret = tb_port_write(out, &val, TB_CFG_PORT,
481 			    out->cap_adap + DP_STATUS_CTRL, 1);
482 	if (ret)
483 		return ret;
484 
485 	do {
486 		ret = tb_port_read(out, &val, TB_CFG_PORT,
487 				   out->cap_adap + DP_STATUS_CTRL, 1);
488 		if (ret)
489 			return ret;
490 		if (!(val & DP_STATUS_CTRL_CMHS))
491 			return 0;
492 		usleep_range(100, 150);
493 	} while (ktime_before(ktime_get(), timeout));
494 
495 	return -ETIMEDOUT;
496 }
497 
498 /*
499  * Returns maximum possible rate from capability supporting only DP 2.0
500  * and below. Used when DP BW allocation mode is not enabled.
501  */
502 static inline u32 tb_dp_cap_get_rate(u32 val)
503 {
504 	u32 rate = (val & DP_COMMON_CAP_RATE_MASK) >> DP_COMMON_CAP_RATE_SHIFT;
505 
506 	switch (rate) {
507 	case DP_COMMON_CAP_RATE_RBR:
508 		return 1620;
509 	case DP_COMMON_CAP_RATE_HBR:
510 		return 2700;
511 	case DP_COMMON_CAP_RATE_HBR2:
512 		return 5400;
513 	case DP_COMMON_CAP_RATE_HBR3:
514 		return 8100;
515 	default:
516 		return 0;
517 	}
518 }
519 
520 /*
521  * Returns maximum possible rate from capability supporting DP 2.1
522  * UHBR20, 13.5 and 10 rates as well. Use only when DP BW allocation
523  * mode is enabled.
524  */
525 static inline u32 tb_dp_cap_get_rate_ext(u32 val)
526 {
527 	if (val & DP_COMMON_CAP_UHBR20)
528 		return 20000;
529 	else if (val & DP_COMMON_CAP_UHBR13_5)
530 		return 13500;
531 	else if (val & DP_COMMON_CAP_UHBR10)
532 		return 10000;
533 
534 	return tb_dp_cap_get_rate(val);
535 }
536 
537 static inline bool tb_dp_is_uhbr_rate(unsigned int rate)
538 {
539 	return rate >= 10000;
540 }
541 
542 static inline u32 tb_dp_cap_set_rate(u32 val, u32 rate)
543 {
544 	val &= ~DP_COMMON_CAP_RATE_MASK;
545 	switch (rate) {
546 	default:
547 		WARN(1, "invalid rate %u passed, defaulting to 1620 MB/s\n", rate);
548 		fallthrough;
549 	case 1620:
550 		val |= DP_COMMON_CAP_RATE_RBR << DP_COMMON_CAP_RATE_SHIFT;
551 		break;
552 	case 2700:
553 		val |= DP_COMMON_CAP_RATE_HBR << DP_COMMON_CAP_RATE_SHIFT;
554 		break;
555 	case 5400:
556 		val |= DP_COMMON_CAP_RATE_HBR2 << DP_COMMON_CAP_RATE_SHIFT;
557 		break;
558 	case 8100:
559 		val |= DP_COMMON_CAP_RATE_HBR3 << DP_COMMON_CAP_RATE_SHIFT;
560 		break;
561 	}
562 	return val;
563 }
564 
565 static inline u32 tb_dp_cap_get_lanes(u32 val)
566 {
567 	u32 lanes = (val & DP_COMMON_CAP_LANES_MASK) >> DP_COMMON_CAP_LANES_SHIFT;
568 
569 	switch (lanes) {
570 	case DP_COMMON_CAP_1_LANE:
571 		return 1;
572 	case DP_COMMON_CAP_2_LANES:
573 		return 2;
574 	case DP_COMMON_CAP_4_LANES:
575 		return 4;
576 	default:
577 		return 0;
578 	}
579 }
580 
581 static inline u32 tb_dp_cap_set_lanes(u32 val, u32 lanes)
582 {
583 	val &= ~DP_COMMON_CAP_LANES_MASK;
584 	switch (lanes) {
585 	default:
586 		WARN(1, "invalid number of lanes %u passed, defaulting to 1\n",
587 		     lanes);
588 		fallthrough;
589 	case 1:
590 		val |= DP_COMMON_CAP_1_LANE << DP_COMMON_CAP_LANES_SHIFT;
591 		break;
592 	case 2:
593 		val |= DP_COMMON_CAP_2_LANES << DP_COMMON_CAP_LANES_SHIFT;
594 		break;
595 	case 4:
596 		val |= DP_COMMON_CAP_4_LANES << DP_COMMON_CAP_LANES_SHIFT;
597 		break;
598 	}
599 	return val;
600 }
601 
602 static unsigned int tb_dp_bandwidth(unsigned int rate, unsigned int lanes)
603 {
604 	/* Tunneling removes the DP 8b/10b 128/132b encoding */
605 	if (tb_dp_is_uhbr_rate(rate))
606 		return rate * lanes * 128 / 132;
607 	return rate * lanes * 8 / 10;
608 }
609 
610 static int tb_dp_reduce_bandwidth(int max_bw, u32 in_rate, u32 in_lanes,
611 				  u32 out_rate, u32 out_lanes, u32 *new_rate,
612 				  u32 *new_lanes)
613 {
614 	static const u32 dp_bw[][2] = {
615 		/* Mb/s, lanes */
616 		{ 8100, 4 }, /* 25920 Mb/s */
617 		{ 5400, 4 }, /* 17280 Mb/s */
618 		{ 8100, 2 }, /* 12960 Mb/s */
619 		{ 2700, 4 }, /* 8640 Mb/s */
620 		{ 5400, 2 }, /* 8640 Mb/s */
621 		{ 8100, 1 }, /* 6480 Mb/s */
622 		{ 1620, 4 }, /* 5184 Mb/s */
623 		{ 5400, 1 }, /* 4320 Mb/s */
624 		{ 2700, 2 }, /* 4320 Mb/s */
625 		{ 1620, 2 }, /* 2592 Mb/s */
626 		{ 2700, 1 }, /* 2160 Mb/s */
627 		{ 1620, 1 }, /* 1296 Mb/s */
628 	};
629 	unsigned int i;
630 
631 	/*
632 	 * Find a combination that can fit into max_bw and does not
633 	 * exceed the maximum rate and lanes supported by the DP OUT and
634 	 * DP IN adapters.
635 	 */
636 	for (i = 0; i < ARRAY_SIZE(dp_bw); i++) {
637 		if (dp_bw[i][0] > out_rate || dp_bw[i][1] > out_lanes)
638 			continue;
639 
640 		if (dp_bw[i][0] > in_rate || dp_bw[i][1] > in_lanes)
641 			continue;
642 
643 		if (tb_dp_bandwidth(dp_bw[i][0], dp_bw[i][1]) <= max_bw) {
644 			*new_rate = dp_bw[i][0];
645 			*new_lanes = dp_bw[i][1];
646 			return 0;
647 		}
648 	}
649 
650 	return -ENOSR;
651 }
652 
653 static int tb_dp_xchg_caps(struct tb_tunnel *tunnel)
654 {
655 	u32 out_dp_cap, out_rate, out_lanes, in_dp_cap, in_rate, in_lanes, bw;
656 	struct tb_port *out = tunnel->dst_port;
657 	struct tb_port *in = tunnel->src_port;
658 	int ret, max_bw;
659 
660 	/*
661 	 * Copy DP_LOCAL_CAP register to DP_REMOTE_CAP register for
662 	 * newer generation hardware.
663 	 */
664 	if (in->sw->generation < 2 || out->sw->generation < 2)
665 		return 0;
666 
667 	/*
668 	 * Perform connection manager handshake between IN and OUT ports
669 	 * before capabilities exchange can take place.
670 	 */
671 	ret = tb_dp_cm_handshake(in, out, 3000);
672 	if (ret)
673 		return ret;
674 
675 	/* Read both DP_LOCAL_CAP registers */
676 	ret = tb_port_read(in, &in_dp_cap, TB_CFG_PORT,
677 			   in->cap_adap + DP_LOCAL_CAP, 1);
678 	if (ret)
679 		return ret;
680 
681 	ret = tb_port_read(out, &out_dp_cap, TB_CFG_PORT,
682 			   out->cap_adap + DP_LOCAL_CAP, 1);
683 	if (ret)
684 		return ret;
685 
686 	/* Write IN local caps to OUT remote caps */
687 	ret = tb_port_write(out, &in_dp_cap, TB_CFG_PORT,
688 			    out->cap_adap + DP_REMOTE_CAP, 1);
689 	if (ret)
690 		return ret;
691 
692 	in_rate = tb_dp_cap_get_rate(in_dp_cap);
693 	in_lanes = tb_dp_cap_get_lanes(in_dp_cap);
694 	tb_tunnel_dbg(tunnel,
695 		      "DP IN maximum supported bandwidth %u Mb/s x%u = %u Mb/s\n",
696 		      in_rate, in_lanes, tb_dp_bandwidth(in_rate, in_lanes));
697 
698 	/*
699 	 * If the tunnel bandwidth is limited (max_bw is set) then see
700 	 * if we need to reduce bandwidth to fit there.
701 	 */
702 	out_rate = tb_dp_cap_get_rate(out_dp_cap);
703 	out_lanes = tb_dp_cap_get_lanes(out_dp_cap);
704 	bw = tb_dp_bandwidth(out_rate, out_lanes);
705 	tb_tunnel_dbg(tunnel,
706 		      "DP OUT maximum supported bandwidth %u Mb/s x%u = %u Mb/s\n",
707 		      out_rate, out_lanes, bw);
708 
709 	if (tb_tunnel_direction_downstream(tunnel))
710 		max_bw = tunnel->max_down;
711 	else
712 		max_bw = tunnel->max_up;
713 
714 	if (max_bw && bw > max_bw) {
715 		u32 new_rate, new_lanes, new_bw;
716 
717 		ret = tb_dp_reduce_bandwidth(max_bw, in_rate, in_lanes,
718 					     out_rate, out_lanes, &new_rate,
719 					     &new_lanes);
720 		if (ret) {
721 			tb_tunnel_info(tunnel, "not enough bandwidth\n");
722 			return ret;
723 		}
724 
725 		new_bw = tb_dp_bandwidth(new_rate, new_lanes);
726 		tb_tunnel_dbg(tunnel,
727 			      "bandwidth reduced to %u Mb/s x%u = %u Mb/s\n",
728 			      new_rate, new_lanes, new_bw);
729 
730 		/*
731 		 * Set new rate and number of lanes before writing it to
732 		 * the IN port remote caps.
733 		 */
734 		out_dp_cap = tb_dp_cap_set_rate(out_dp_cap, new_rate);
735 		out_dp_cap = tb_dp_cap_set_lanes(out_dp_cap, new_lanes);
736 	}
737 
738 	/*
739 	 * Titan Ridge does not disable AUX timers when it gets
740 	 * SET_CONFIG with SET_LTTPR_MODE set. This causes problems with
741 	 * DP tunneling.
742 	 */
743 	if (tb_route(out->sw) && tb_switch_is_titan_ridge(out->sw)) {
744 		out_dp_cap |= DP_COMMON_CAP_LTTPR_NS;
745 		tb_tunnel_dbg(tunnel, "disabling LTTPR\n");
746 	}
747 
748 	return tb_port_write(in, &out_dp_cap, TB_CFG_PORT,
749 			     in->cap_adap + DP_REMOTE_CAP, 1);
750 }
751 
752 static int tb_dp_bandwidth_alloc_mode_enable(struct tb_tunnel *tunnel)
753 {
754 	int ret, estimated_bw, granularity, tmp;
755 	struct tb_port *out = tunnel->dst_port;
756 	struct tb_port *in = tunnel->src_port;
757 	u32 out_dp_cap, out_rate, out_lanes;
758 	u32 in_dp_cap, in_rate, in_lanes;
759 	u32 rate, lanes;
760 
761 	if (!bw_alloc_mode)
762 		return 0;
763 
764 	ret = usb4_dp_port_set_cm_bandwidth_mode_supported(in, true);
765 	if (ret)
766 		return ret;
767 
768 	ret = usb4_dp_port_set_group_id(in, in->group->index);
769 	if (ret)
770 		return ret;
771 
772 	/*
773 	 * Get the non-reduced rate and lanes based on the lowest
774 	 * capability of both adapters.
775 	 */
776 	ret = tb_port_read(in, &in_dp_cap, TB_CFG_PORT,
777 			   in->cap_adap + DP_LOCAL_CAP, 1);
778 	if (ret)
779 		return ret;
780 
781 	ret = tb_port_read(out, &out_dp_cap, TB_CFG_PORT,
782 			   out->cap_adap + DP_LOCAL_CAP, 1);
783 	if (ret)
784 		return ret;
785 
786 	in_rate = tb_dp_cap_get_rate(in_dp_cap);
787 	in_lanes = tb_dp_cap_get_lanes(in_dp_cap);
788 	out_rate = tb_dp_cap_get_rate(out_dp_cap);
789 	out_lanes = tb_dp_cap_get_lanes(out_dp_cap);
790 
791 	rate = min(in_rate, out_rate);
792 	lanes = min(in_lanes, out_lanes);
793 	tmp = tb_dp_bandwidth(rate, lanes);
794 
795 	tb_tunnel_dbg(tunnel, "non-reduced bandwidth %u Mb/s x%u = %u Mb/s\n",
796 		      rate, lanes, tmp);
797 
798 	ret = usb4_dp_port_set_nrd(in, rate, lanes);
799 	if (ret)
800 		return ret;
801 
802 	/*
803 	 * Pick up granularity that supports maximum possible bandwidth.
804 	 * For that we use the UHBR rates too.
805 	 */
806 	in_rate = tb_dp_cap_get_rate_ext(in_dp_cap);
807 	out_rate = tb_dp_cap_get_rate_ext(out_dp_cap);
808 	rate = min(in_rate, out_rate);
809 	tmp = tb_dp_bandwidth(rate, lanes);
810 
811 	tb_tunnel_dbg(tunnel,
812 		      "maximum bandwidth through allocation mode %u Mb/s x%u = %u Mb/s\n",
813 		      rate, lanes, tmp);
814 
815 	for (granularity = 250; tmp / granularity > 255 && granularity <= 1000;
816 	     granularity *= 2)
817 		;
818 
819 	tb_tunnel_dbg(tunnel, "granularity %d Mb/s\n", granularity);
820 
821 	/*
822 	 * Returns -EINVAL if granularity above is outside of the
823 	 * accepted ranges.
824 	 */
825 	ret = usb4_dp_port_set_granularity(in, granularity);
826 	if (ret)
827 		return ret;
828 
829 	/*
830 	 * Bandwidth estimation is pretty much what we have in
831 	 * max_up/down fields. For discovery we just read what the
832 	 * estimation was set to.
833 	 */
834 	if (tb_tunnel_direction_downstream(tunnel))
835 		estimated_bw = tunnel->max_down;
836 	else
837 		estimated_bw = tunnel->max_up;
838 
839 	tb_tunnel_dbg(tunnel, "estimated bandwidth %d Mb/s\n", estimated_bw);
840 
841 	ret = usb4_dp_port_set_estimated_bandwidth(in, estimated_bw);
842 	if (ret)
843 		return ret;
844 
845 	/* Initial allocation should be 0 according the spec */
846 	ret = usb4_dp_port_allocate_bandwidth(in, 0);
847 	if (ret)
848 		return ret;
849 
850 	tb_tunnel_dbg(tunnel, "bandwidth allocation mode enabled\n");
851 	return 0;
852 }
853 
854 static int tb_dp_init(struct tb_tunnel *tunnel)
855 {
856 	struct tb_port *in = tunnel->src_port;
857 	struct tb_switch *sw = in->sw;
858 	struct tb *tb = in->sw->tb;
859 	int ret;
860 
861 	ret = tb_dp_xchg_caps(tunnel);
862 	if (ret)
863 		return ret;
864 
865 	if (!tb_switch_is_usb4(sw))
866 		return 0;
867 
868 	if (!usb4_dp_port_bandwidth_mode_supported(in))
869 		return 0;
870 
871 	tb_tunnel_dbg(tunnel, "bandwidth allocation mode supported\n");
872 
873 	ret = usb4_dp_port_set_cm_id(in, tb->index);
874 	if (ret)
875 		return ret;
876 
877 	return tb_dp_bandwidth_alloc_mode_enable(tunnel);
878 }
879 
880 static void tb_dp_deinit(struct tb_tunnel *tunnel)
881 {
882 	struct tb_port *in = tunnel->src_port;
883 
884 	if (!usb4_dp_port_bandwidth_mode_supported(in))
885 		return;
886 	if (usb4_dp_port_bandwidth_mode_enabled(in)) {
887 		usb4_dp_port_set_cm_bandwidth_mode_supported(in, false);
888 		tb_tunnel_dbg(tunnel, "bandwidth allocation mode disabled\n");
889 	}
890 }
891 
892 static int tb_dp_activate(struct tb_tunnel *tunnel, bool active)
893 {
894 	int ret;
895 
896 	if (active) {
897 		struct tb_path **paths;
898 		int last;
899 
900 		paths = tunnel->paths;
901 		last = paths[TB_DP_VIDEO_PATH_OUT]->path_length - 1;
902 
903 		tb_dp_port_set_hops(tunnel->src_port,
904 			paths[TB_DP_VIDEO_PATH_OUT]->hops[0].in_hop_index,
905 			paths[TB_DP_AUX_PATH_OUT]->hops[0].in_hop_index,
906 			paths[TB_DP_AUX_PATH_IN]->hops[last].next_hop_index);
907 
908 		tb_dp_port_set_hops(tunnel->dst_port,
909 			paths[TB_DP_VIDEO_PATH_OUT]->hops[last].next_hop_index,
910 			paths[TB_DP_AUX_PATH_IN]->hops[0].in_hop_index,
911 			paths[TB_DP_AUX_PATH_OUT]->hops[last].next_hop_index);
912 	} else {
913 		tb_dp_port_hpd_clear(tunnel->src_port);
914 		tb_dp_port_set_hops(tunnel->src_port, 0, 0, 0);
915 		if (tb_port_is_dpout(tunnel->dst_port))
916 			tb_dp_port_set_hops(tunnel->dst_port, 0, 0, 0);
917 	}
918 
919 	ret = tb_dp_port_enable(tunnel->src_port, active);
920 	if (ret)
921 		return ret;
922 
923 	if (tb_port_is_dpout(tunnel->dst_port))
924 		return tb_dp_port_enable(tunnel->dst_port, active);
925 
926 	return 0;
927 }
928 
929 /**
930  * tb_dp_bandwidth_mode_maximum_bandwidth() - Maximum possible bandwidth
931  * @tunnel: DP tunnel to check
932  * @max_bw_rounded: Maximum bandwidth in Mb/s rounded up to the next granularity
933  *
934  * Returns maximum possible bandwidth for this tunnel in Mb/s.
935  */
936 static int tb_dp_bandwidth_mode_maximum_bandwidth(struct tb_tunnel *tunnel,
937 						  int *max_bw_rounded)
938 {
939 	struct tb_port *in = tunnel->src_port;
940 	int ret, rate, lanes, max_bw;
941 	u32 cap;
942 
943 	/*
944 	 * DP IN adapter DP_LOCAL_CAP gets updated to the lowest AUX
945 	 * read parameter values so this so we can use this to determine
946 	 * the maximum possible bandwidth over this link.
947 	 *
948 	 * See USB4 v2 spec 1.0 10.4.4.5.
949 	 */
950 	ret = tb_port_read(in, &cap, TB_CFG_PORT,
951 			   in->cap_adap + DP_LOCAL_CAP, 1);
952 	if (ret)
953 		return ret;
954 
955 	rate = tb_dp_cap_get_rate_ext(cap);
956 	lanes = tb_dp_cap_get_lanes(cap);
957 
958 	max_bw = tb_dp_bandwidth(rate, lanes);
959 
960 	if (max_bw_rounded) {
961 		ret = usb4_dp_port_granularity(in);
962 		if (ret < 0)
963 			return ret;
964 		*max_bw_rounded = roundup(max_bw, ret);
965 	}
966 
967 	return max_bw;
968 }
969 
970 static int tb_dp_bandwidth_mode_consumed_bandwidth(struct tb_tunnel *tunnel,
971 						   int *consumed_up,
972 						   int *consumed_down)
973 {
974 	struct tb_port *in = tunnel->src_port;
975 	int ret, allocated_bw, max_bw_rounded;
976 
977 	if (!usb4_dp_port_bandwidth_mode_enabled(in))
978 		return -EOPNOTSUPP;
979 
980 	if (!tunnel->bw_mode)
981 		return -EOPNOTSUPP;
982 
983 	/* Read what was allocated previously if any */
984 	ret = usb4_dp_port_allocated_bandwidth(in);
985 	if (ret < 0)
986 		return ret;
987 	allocated_bw = ret;
988 
989 	ret = tb_dp_bandwidth_mode_maximum_bandwidth(tunnel, &max_bw_rounded);
990 	if (ret < 0)
991 		return ret;
992 	if (allocated_bw == max_bw_rounded)
993 		allocated_bw = ret;
994 
995 	if (tb_tunnel_direction_downstream(tunnel)) {
996 		*consumed_up = 0;
997 		*consumed_down = allocated_bw;
998 	} else {
999 		*consumed_up = allocated_bw;
1000 		*consumed_down = 0;
1001 	}
1002 
1003 	return 0;
1004 }
1005 
1006 static int tb_dp_allocated_bandwidth(struct tb_tunnel *tunnel, int *allocated_up,
1007 				     int *allocated_down)
1008 {
1009 	struct tb_port *in = tunnel->src_port;
1010 
1011 	/*
1012 	 * If we have already set the allocated bandwidth then use that.
1013 	 * Otherwise we read it from the DPRX.
1014 	 */
1015 	if (usb4_dp_port_bandwidth_mode_enabled(in) && tunnel->bw_mode) {
1016 		int ret, allocated_bw, max_bw_rounded;
1017 
1018 		ret = usb4_dp_port_allocated_bandwidth(in);
1019 		if (ret < 0)
1020 			return ret;
1021 		allocated_bw = ret;
1022 
1023 		ret = tb_dp_bandwidth_mode_maximum_bandwidth(tunnel,
1024 							     &max_bw_rounded);
1025 		if (ret < 0)
1026 			return ret;
1027 		if (allocated_bw == max_bw_rounded)
1028 			allocated_bw = ret;
1029 
1030 		if (tb_tunnel_direction_downstream(tunnel)) {
1031 			*allocated_up = 0;
1032 			*allocated_down = allocated_bw;
1033 		} else {
1034 			*allocated_up = allocated_bw;
1035 			*allocated_down = 0;
1036 		}
1037 		return 0;
1038 	}
1039 
1040 	return tunnel->consumed_bandwidth(tunnel, allocated_up,
1041 					  allocated_down);
1042 }
1043 
1044 static int tb_dp_alloc_bandwidth(struct tb_tunnel *tunnel, int *alloc_up,
1045 				 int *alloc_down)
1046 {
1047 	struct tb_port *in = tunnel->src_port;
1048 	int max_bw_rounded, ret, tmp;
1049 
1050 	if (!usb4_dp_port_bandwidth_mode_enabled(in))
1051 		return -EOPNOTSUPP;
1052 
1053 	ret = tb_dp_bandwidth_mode_maximum_bandwidth(tunnel, &max_bw_rounded);
1054 	if (ret < 0)
1055 		return ret;
1056 
1057 	if (tb_tunnel_direction_downstream(tunnel)) {
1058 		tmp = min(*alloc_down, max_bw_rounded);
1059 		ret = usb4_dp_port_allocate_bandwidth(in, tmp);
1060 		if (ret)
1061 			return ret;
1062 		*alloc_down = tmp;
1063 		*alloc_up = 0;
1064 	} else {
1065 		tmp = min(*alloc_up, max_bw_rounded);
1066 		ret = usb4_dp_port_allocate_bandwidth(in, tmp);
1067 		if (ret)
1068 			return ret;
1069 		*alloc_down = 0;
1070 		*alloc_up = tmp;
1071 	}
1072 
1073 	/* Now we can use BW mode registers to figure out the bandwidth */
1074 	/* TODO: need to handle discovery too */
1075 	tunnel->bw_mode = true;
1076 	return 0;
1077 }
1078 
1079 static int tb_dp_wait_dprx(struct tb_tunnel *tunnel, int timeout_msec)
1080 {
1081 	ktime_t timeout = ktime_add_ms(ktime_get(), timeout_msec);
1082 	struct tb_port *in = tunnel->src_port;
1083 
1084 	/*
1085 	 * Wait for DPRX done. Normally it should be already set for
1086 	 * active tunnel.
1087 	 */
1088 	do {
1089 		u32 val;
1090 		int ret;
1091 
1092 		ret = tb_port_read(in, &val, TB_CFG_PORT,
1093 				   in->cap_adap + DP_COMMON_CAP, 1);
1094 		if (ret)
1095 			return ret;
1096 
1097 		if (val & DP_COMMON_CAP_DPRX_DONE) {
1098 			tb_tunnel_dbg(tunnel, "DPRX read done\n");
1099 			return 0;
1100 		}
1101 		usleep_range(100, 150);
1102 	} while (ktime_before(ktime_get(), timeout));
1103 
1104 	tb_tunnel_dbg(tunnel, "DPRX read timeout\n");
1105 	return -ETIMEDOUT;
1106 }
1107 
1108 /* Read cap from tunnel DP IN */
1109 static int tb_dp_read_cap(struct tb_tunnel *tunnel, unsigned int cap, u32 *rate,
1110 			  u32 *lanes)
1111 {
1112 	struct tb_port *in = tunnel->src_port;
1113 	u32 val;
1114 	int ret;
1115 
1116 	switch (cap) {
1117 	case DP_LOCAL_CAP:
1118 	case DP_REMOTE_CAP:
1119 	case DP_COMMON_CAP:
1120 		break;
1121 
1122 	default:
1123 		tb_tunnel_WARN(tunnel, "invalid capability index %#x\n", cap);
1124 		return -EINVAL;
1125 	}
1126 
1127 	/*
1128 	 * Read from the copied remote cap so that we take into account
1129 	 * if capabilities were reduced during exchange.
1130 	 */
1131 	ret = tb_port_read(in, &val, TB_CFG_PORT, in->cap_adap + cap, 1);
1132 	if (ret)
1133 		return ret;
1134 
1135 	*rate = tb_dp_cap_get_rate(val);
1136 	*lanes = tb_dp_cap_get_lanes(val);
1137 	return 0;
1138 }
1139 
1140 static int tb_dp_maximum_bandwidth(struct tb_tunnel *tunnel, int *max_up,
1141 				   int *max_down)
1142 {
1143 	int ret;
1144 
1145 	if (!usb4_dp_port_bandwidth_mode_enabled(tunnel->src_port))
1146 		return -EOPNOTSUPP;
1147 
1148 	ret = tb_dp_bandwidth_mode_maximum_bandwidth(tunnel, NULL);
1149 	if (ret < 0)
1150 		return ret;
1151 
1152 	if (tb_tunnel_direction_downstream(tunnel)) {
1153 		*max_up = 0;
1154 		*max_down = ret;
1155 	} else {
1156 		*max_up = ret;
1157 		*max_down = 0;
1158 	}
1159 
1160 	return 0;
1161 }
1162 
1163 static int tb_dp_consumed_bandwidth(struct tb_tunnel *tunnel, int *consumed_up,
1164 				    int *consumed_down)
1165 {
1166 	const struct tb_switch *sw = tunnel->src_port->sw;
1167 	u32 rate = 0, lanes = 0;
1168 	int ret;
1169 
1170 	if (tb_dp_is_usb4(sw)) {
1171 		/*
1172 		 * On USB4 routers check if the bandwidth allocation
1173 		 * mode is enabled first and then read the bandwidth
1174 		 * through those registers.
1175 		 */
1176 		ret = tb_dp_bandwidth_mode_consumed_bandwidth(tunnel, consumed_up,
1177 							      consumed_down);
1178 		if (ret < 0) {
1179 			if (ret != -EOPNOTSUPP)
1180 				return ret;
1181 		} else if (!ret) {
1182 			return 0;
1183 		}
1184 		/*
1185 		 * Then see if the DPRX negotiation is ready and if yes
1186 		 * return that bandwidth (it may be smaller than the
1187 		 * reduced one). According to VESA spec, the DPRX
1188 		 * negotiation shall compete in 5 seconds after tunnel
1189 		 * established. We give it 100ms extra just in case.
1190 		 */
1191 		ret = tb_dp_wait_dprx(tunnel, 5100);
1192 		if (ret)
1193 			return ret;
1194 		ret = tb_dp_read_cap(tunnel, DP_COMMON_CAP, &rate, &lanes);
1195 		if (ret)
1196 			return ret;
1197 	} else if (sw->generation >= 2) {
1198 		ret = tb_dp_read_cap(tunnel, DP_REMOTE_CAP, &rate, &lanes);
1199 		if (ret)
1200 			return ret;
1201 	} else {
1202 		/* No bandwidth management for legacy devices  */
1203 		*consumed_up = 0;
1204 		*consumed_down = 0;
1205 		return 0;
1206 	}
1207 
1208 	if (tb_tunnel_direction_downstream(tunnel)) {
1209 		*consumed_up = 0;
1210 		*consumed_down = tb_dp_bandwidth(rate, lanes);
1211 	} else {
1212 		*consumed_up = tb_dp_bandwidth(rate, lanes);
1213 		*consumed_down = 0;
1214 	}
1215 
1216 	return 0;
1217 }
1218 
1219 static void tb_dp_init_aux_credits(struct tb_path_hop *hop)
1220 {
1221 	struct tb_port *port = hop->in_port;
1222 	struct tb_switch *sw = port->sw;
1223 
1224 	if (tb_port_use_credit_allocation(port))
1225 		hop->initial_credits = sw->min_dp_aux_credits;
1226 	else
1227 		hop->initial_credits = 1;
1228 }
1229 
1230 static void tb_dp_init_aux_path(struct tb_path *path, bool pm_support)
1231 {
1232 	struct tb_path_hop *hop;
1233 
1234 	path->egress_fc_enable = TB_PATH_SOURCE | TB_PATH_INTERNAL;
1235 	path->egress_shared_buffer = TB_PATH_NONE;
1236 	path->ingress_fc_enable = TB_PATH_ALL;
1237 	path->ingress_shared_buffer = TB_PATH_NONE;
1238 	path->priority = TB_DP_AUX_PRIORITY;
1239 	path->weight = TB_DP_AUX_WEIGHT;
1240 
1241 	tb_path_for_each_hop(path, hop) {
1242 		tb_dp_init_aux_credits(hop);
1243 		if (pm_support)
1244 			tb_init_pm_support(hop);
1245 	}
1246 }
1247 
1248 static int tb_dp_init_video_credits(struct tb_path_hop *hop)
1249 {
1250 	struct tb_port *port = hop->in_port;
1251 	struct tb_switch *sw = port->sw;
1252 
1253 	if (tb_port_use_credit_allocation(port)) {
1254 		unsigned int nfc_credits;
1255 		size_t max_dp_streams;
1256 
1257 		tb_available_credits(port, &max_dp_streams);
1258 		/*
1259 		 * Read the number of currently allocated NFC credits
1260 		 * from the lane adapter. Since we only use them for DP
1261 		 * tunneling we can use that to figure out how many DP
1262 		 * tunnels already go through the lane adapter.
1263 		 */
1264 		nfc_credits = port->config.nfc_credits &
1265 				ADP_CS_4_NFC_BUFFERS_MASK;
1266 		if (nfc_credits / sw->min_dp_main_credits > max_dp_streams)
1267 			return -ENOSPC;
1268 
1269 		hop->nfc_credits = sw->min_dp_main_credits;
1270 	} else {
1271 		hop->nfc_credits = min(port->total_credits - 2, 12U);
1272 	}
1273 
1274 	return 0;
1275 }
1276 
1277 static int tb_dp_init_video_path(struct tb_path *path, bool pm_support)
1278 {
1279 	struct tb_path_hop *hop;
1280 
1281 	path->egress_fc_enable = TB_PATH_NONE;
1282 	path->egress_shared_buffer = TB_PATH_NONE;
1283 	path->ingress_fc_enable = TB_PATH_NONE;
1284 	path->ingress_shared_buffer = TB_PATH_NONE;
1285 	path->priority = TB_DP_VIDEO_PRIORITY;
1286 	path->weight = TB_DP_VIDEO_WEIGHT;
1287 
1288 	tb_path_for_each_hop(path, hop) {
1289 		int ret;
1290 
1291 		ret = tb_dp_init_video_credits(hop);
1292 		if (ret)
1293 			return ret;
1294 		if (pm_support)
1295 			tb_init_pm_support(hop);
1296 	}
1297 
1298 	return 0;
1299 }
1300 
1301 static void tb_dp_dump(struct tb_tunnel *tunnel)
1302 {
1303 	struct tb_port *in, *out;
1304 	u32 dp_cap, rate, lanes;
1305 
1306 	in = tunnel->src_port;
1307 	out = tunnel->dst_port;
1308 
1309 	if (tb_port_read(in, &dp_cap, TB_CFG_PORT,
1310 			 in->cap_adap + DP_LOCAL_CAP, 1))
1311 		return;
1312 
1313 	rate = tb_dp_cap_get_rate(dp_cap);
1314 	lanes = tb_dp_cap_get_lanes(dp_cap);
1315 
1316 	tb_tunnel_dbg(tunnel,
1317 		      "DP IN maximum supported bandwidth %u Mb/s x%u = %u Mb/s\n",
1318 		      rate, lanes, tb_dp_bandwidth(rate, lanes));
1319 
1320 	if (tb_port_read(out, &dp_cap, TB_CFG_PORT,
1321 			 out->cap_adap + DP_LOCAL_CAP, 1))
1322 		return;
1323 
1324 	rate = tb_dp_cap_get_rate(dp_cap);
1325 	lanes = tb_dp_cap_get_lanes(dp_cap);
1326 
1327 	tb_tunnel_dbg(tunnel,
1328 		      "DP OUT maximum supported bandwidth %u Mb/s x%u = %u Mb/s\n",
1329 		      rate, lanes, tb_dp_bandwidth(rate, lanes));
1330 
1331 	if (tb_port_read(in, &dp_cap, TB_CFG_PORT,
1332 			 in->cap_adap + DP_REMOTE_CAP, 1))
1333 		return;
1334 
1335 	rate = tb_dp_cap_get_rate(dp_cap);
1336 	lanes = tb_dp_cap_get_lanes(dp_cap);
1337 
1338 	tb_tunnel_dbg(tunnel, "reduced bandwidth %u Mb/s x%u = %u Mb/s\n",
1339 		      rate, lanes, tb_dp_bandwidth(rate, lanes));
1340 }
1341 
1342 /**
1343  * tb_tunnel_discover_dp() - Discover existing Display Port tunnels
1344  * @tb: Pointer to the domain structure
1345  * @in: DP in adapter
1346  * @alloc_hopid: Allocate HopIDs from visited ports
1347  *
1348  * If @in adapter is active, follows the tunnel to the DP out adapter
1349  * and back. Returns the discovered tunnel or %NULL if there was no
1350  * tunnel.
1351  *
1352  * Return: DP tunnel or %NULL if no tunnel found.
1353  */
1354 struct tb_tunnel *tb_tunnel_discover_dp(struct tb *tb, struct tb_port *in,
1355 					bool alloc_hopid)
1356 {
1357 	struct tb_tunnel *tunnel;
1358 	struct tb_port *port;
1359 	struct tb_path *path;
1360 
1361 	if (!tb_dp_port_is_enabled(in))
1362 		return NULL;
1363 
1364 	tunnel = tb_tunnel_alloc(tb, 3, TB_TUNNEL_DP);
1365 	if (!tunnel)
1366 		return NULL;
1367 
1368 	tunnel->init = tb_dp_init;
1369 	tunnel->deinit = tb_dp_deinit;
1370 	tunnel->activate = tb_dp_activate;
1371 	tunnel->maximum_bandwidth = tb_dp_maximum_bandwidth;
1372 	tunnel->allocated_bandwidth = tb_dp_allocated_bandwidth;
1373 	tunnel->alloc_bandwidth = tb_dp_alloc_bandwidth;
1374 	tunnel->consumed_bandwidth = tb_dp_consumed_bandwidth;
1375 	tunnel->src_port = in;
1376 
1377 	path = tb_path_discover(in, TB_DP_VIDEO_HOPID, NULL, -1,
1378 				&tunnel->dst_port, "Video", alloc_hopid);
1379 	if (!path) {
1380 		/* Just disable the DP IN port */
1381 		tb_dp_port_enable(in, false);
1382 		goto err_free;
1383 	}
1384 	tunnel->paths[TB_DP_VIDEO_PATH_OUT] = path;
1385 	if (tb_dp_init_video_path(tunnel->paths[TB_DP_VIDEO_PATH_OUT], false))
1386 		goto err_free;
1387 
1388 	path = tb_path_discover(in, TB_DP_AUX_TX_HOPID, NULL, -1, NULL, "AUX TX",
1389 				alloc_hopid);
1390 	if (!path)
1391 		goto err_deactivate;
1392 	tunnel->paths[TB_DP_AUX_PATH_OUT] = path;
1393 	tb_dp_init_aux_path(tunnel->paths[TB_DP_AUX_PATH_OUT], false);
1394 
1395 	path = tb_path_discover(tunnel->dst_port, -1, in, TB_DP_AUX_RX_HOPID,
1396 				&port, "AUX RX", alloc_hopid);
1397 	if (!path)
1398 		goto err_deactivate;
1399 	tunnel->paths[TB_DP_AUX_PATH_IN] = path;
1400 	tb_dp_init_aux_path(tunnel->paths[TB_DP_AUX_PATH_IN], false);
1401 
1402 	/* Validate that the tunnel is complete */
1403 	if (!tb_port_is_dpout(tunnel->dst_port)) {
1404 		tb_port_warn(in, "path does not end on a DP adapter, cleaning up\n");
1405 		goto err_deactivate;
1406 	}
1407 
1408 	if (!tb_dp_port_is_enabled(tunnel->dst_port))
1409 		goto err_deactivate;
1410 
1411 	if (!tb_dp_port_hpd_is_active(tunnel->dst_port))
1412 		goto err_deactivate;
1413 
1414 	if (port != tunnel->src_port) {
1415 		tb_tunnel_warn(tunnel, "path is not complete, cleaning up\n");
1416 		goto err_deactivate;
1417 	}
1418 
1419 	tb_dp_dump(tunnel);
1420 
1421 	tb_tunnel_dbg(tunnel, "discovered\n");
1422 	return tunnel;
1423 
1424 err_deactivate:
1425 	tb_tunnel_deactivate(tunnel);
1426 err_free:
1427 	tb_tunnel_free(tunnel);
1428 
1429 	return NULL;
1430 }
1431 
1432 /**
1433  * tb_tunnel_alloc_dp() - allocate a Display Port tunnel
1434  * @tb: Pointer to the domain structure
1435  * @in: DP in adapter port
1436  * @out: DP out adapter port
1437  * @link_nr: Preferred lane adapter when the link is not bonded
1438  * @max_up: Maximum available upstream bandwidth for the DP tunnel.
1439  *	    %0 if no available bandwidth.
1440  * @max_down: Maximum available downstream bandwidth for the DP tunnel.
1441  *	      %0 if no available bandwidth.
1442  *
1443  * Allocates a tunnel between @in and @out that is capable of tunneling
1444  * Display Port traffic.
1445  *
1446  * Return: Returns a tb_tunnel on success or NULL on failure.
1447  */
1448 struct tb_tunnel *tb_tunnel_alloc_dp(struct tb *tb, struct tb_port *in,
1449 				     struct tb_port *out, int link_nr,
1450 				     int max_up, int max_down)
1451 {
1452 	struct tb_tunnel *tunnel;
1453 	struct tb_path **paths;
1454 	struct tb_path *path;
1455 	bool pm_support;
1456 
1457 	if (WARN_ON(!in->cap_adap || !out->cap_adap))
1458 		return NULL;
1459 
1460 	tunnel = tb_tunnel_alloc(tb, 3, TB_TUNNEL_DP);
1461 	if (!tunnel)
1462 		return NULL;
1463 
1464 	tunnel->init = tb_dp_init;
1465 	tunnel->deinit = tb_dp_deinit;
1466 	tunnel->activate = tb_dp_activate;
1467 	tunnel->maximum_bandwidth = tb_dp_maximum_bandwidth;
1468 	tunnel->allocated_bandwidth = tb_dp_allocated_bandwidth;
1469 	tunnel->alloc_bandwidth = tb_dp_alloc_bandwidth;
1470 	tunnel->consumed_bandwidth = tb_dp_consumed_bandwidth;
1471 	tunnel->src_port = in;
1472 	tunnel->dst_port = out;
1473 	tunnel->max_up = max_up;
1474 	tunnel->max_down = max_down;
1475 
1476 	paths = tunnel->paths;
1477 	pm_support = usb4_switch_version(in->sw) >= 2;
1478 
1479 	path = tb_path_alloc(tb, in, TB_DP_VIDEO_HOPID, out, TB_DP_VIDEO_HOPID,
1480 			     link_nr, "Video");
1481 	if (!path)
1482 		goto err_free;
1483 	tb_dp_init_video_path(path, pm_support);
1484 	paths[TB_DP_VIDEO_PATH_OUT] = path;
1485 
1486 	path = tb_path_alloc(tb, in, TB_DP_AUX_TX_HOPID, out,
1487 			     TB_DP_AUX_TX_HOPID, link_nr, "AUX TX");
1488 	if (!path)
1489 		goto err_free;
1490 	tb_dp_init_aux_path(path, pm_support);
1491 	paths[TB_DP_AUX_PATH_OUT] = path;
1492 
1493 	path = tb_path_alloc(tb, out, TB_DP_AUX_RX_HOPID, in,
1494 			     TB_DP_AUX_RX_HOPID, link_nr, "AUX RX");
1495 	if (!path)
1496 		goto err_free;
1497 	tb_dp_init_aux_path(path, pm_support);
1498 	paths[TB_DP_AUX_PATH_IN] = path;
1499 
1500 	return tunnel;
1501 
1502 err_free:
1503 	tb_tunnel_free(tunnel);
1504 	return NULL;
1505 }
1506 
1507 static unsigned int tb_dma_available_credits(const struct tb_port *port)
1508 {
1509 	const struct tb_switch *sw = port->sw;
1510 	int credits;
1511 
1512 	credits = tb_available_credits(port, NULL);
1513 	if (tb_acpi_may_tunnel_pcie())
1514 		credits -= sw->max_pcie_credits;
1515 	credits -= port->dma_credits;
1516 
1517 	return credits > 0 ? credits : 0;
1518 }
1519 
1520 static int tb_dma_reserve_credits(struct tb_path_hop *hop, unsigned int credits)
1521 {
1522 	struct tb_port *port = hop->in_port;
1523 
1524 	if (tb_port_use_credit_allocation(port)) {
1525 		unsigned int available = tb_dma_available_credits(port);
1526 
1527 		/*
1528 		 * Need to have at least TB_MIN_DMA_CREDITS, otherwise
1529 		 * DMA path cannot be established.
1530 		 */
1531 		if (available < TB_MIN_DMA_CREDITS)
1532 			return -ENOSPC;
1533 
1534 		while (credits > available)
1535 			credits--;
1536 
1537 		tb_port_dbg(port, "reserving %u credits for DMA path\n",
1538 			    credits);
1539 
1540 		port->dma_credits += credits;
1541 	} else {
1542 		if (tb_port_is_null(port))
1543 			credits = port->bonded ? 14 : 6;
1544 		else
1545 			credits = min(port->total_credits, credits);
1546 	}
1547 
1548 	hop->initial_credits = credits;
1549 	return 0;
1550 }
1551 
1552 /* Path from lane adapter to NHI */
1553 static int tb_dma_init_rx_path(struct tb_path *path, unsigned int credits)
1554 {
1555 	struct tb_path_hop *hop;
1556 	unsigned int i, tmp;
1557 
1558 	path->egress_fc_enable = TB_PATH_SOURCE | TB_PATH_INTERNAL;
1559 	path->ingress_fc_enable = TB_PATH_ALL;
1560 	path->egress_shared_buffer = TB_PATH_NONE;
1561 	path->ingress_shared_buffer = TB_PATH_NONE;
1562 	path->priority = TB_DMA_PRIORITY;
1563 	path->weight = TB_DMA_WEIGHT;
1564 	path->clear_fc = true;
1565 
1566 	/*
1567 	 * First lane adapter is the one connected to the remote host.
1568 	 * We don't tunnel other traffic over this link so can use all
1569 	 * the credits (except the ones reserved for control traffic).
1570 	 */
1571 	hop = &path->hops[0];
1572 	tmp = min(tb_usable_credits(hop->in_port), credits);
1573 	hop->initial_credits = tmp;
1574 	hop->in_port->dma_credits += tmp;
1575 
1576 	for (i = 1; i < path->path_length; i++) {
1577 		int ret;
1578 
1579 		ret = tb_dma_reserve_credits(&path->hops[i], credits);
1580 		if (ret)
1581 			return ret;
1582 	}
1583 
1584 	return 0;
1585 }
1586 
1587 /* Path from NHI to lane adapter */
1588 static int tb_dma_init_tx_path(struct tb_path *path, unsigned int credits)
1589 {
1590 	struct tb_path_hop *hop;
1591 
1592 	path->egress_fc_enable = TB_PATH_ALL;
1593 	path->ingress_fc_enable = TB_PATH_ALL;
1594 	path->egress_shared_buffer = TB_PATH_NONE;
1595 	path->ingress_shared_buffer = TB_PATH_NONE;
1596 	path->priority = TB_DMA_PRIORITY;
1597 	path->weight = TB_DMA_WEIGHT;
1598 	path->clear_fc = true;
1599 
1600 	tb_path_for_each_hop(path, hop) {
1601 		int ret;
1602 
1603 		ret = tb_dma_reserve_credits(hop, credits);
1604 		if (ret)
1605 			return ret;
1606 	}
1607 
1608 	return 0;
1609 }
1610 
1611 static void tb_dma_release_credits(struct tb_path_hop *hop)
1612 {
1613 	struct tb_port *port = hop->in_port;
1614 
1615 	if (tb_port_use_credit_allocation(port)) {
1616 		port->dma_credits -= hop->initial_credits;
1617 
1618 		tb_port_dbg(port, "released %u DMA path credits\n",
1619 			    hop->initial_credits);
1620 	}
1621 }
1622 
1623 static void tb_dma_deinit_path(struct tb_path *path)
1624 {
1625 	struct tb_path_hop *hop;
1626 
1627 	tb_path_for_each_hop(path, hop)
1628 		tb_dma_release_credits(hop);
1629 }
1630 
1631 static void tb_dma_deinit(struct tb_tunnel *tunnel)
1632 {
1633 	int i;
1634 
1635 	for (i = 0; i < tunnel->npaths; i++) {
1636 		if (!tunnel->paths[i])
1637 			continue;
1638 		tb_dma_deinit_path(tunnel->paths[i]);
1639 	}
1640 }
1641 
1642 /**
1643  * tb_tunnel_alloc_dma() - allocate a DMA tunnel
1644  * @tb: Pointer to the domain structure
1645  * @nhi: Host controller port
1646  * @dst: Destination null port which the other domain is connected to
1647  * @transmit_path: HopID used for transmitting packets
1648  * @transmit_ring: NHI ring number used to send packets towards the
1649  *		   other domain. Set to %-1 if TX path is not needed.
1650  * @receive_path: HopID used for receiving packets
1651  * @receive_ring: NHI ring number used to receive packets from the
1652  *		  other domain. Set to %-1 if RX path is not needed.
1653  *
1654  * Return: Returns a tb_tunnel on success or NULL on failure.
1655  */
1656 struct tb_tunnel *tb_tunnel_alloc_dma(struct tb *tb, struct tb_port *nhi,
1657 				      struct tb_port *dst, int transmit_path,
1658 				      int transmit_ring, int receive_path,
1659 				      int receive_ring)
1660 {
1661 	struct tb_tunnel *tunnel;
1662 	size_t npaths = 0, i = 0;
1663 	struct tb_path *path;
1664 	int credits;
1665 
1666 	/* Ring 0 is reserved for control channel */
1667 	if (WARN_ON(!receive_ring || !transmit_ring))
1668 		return NULL;
1669 
1670 	if (receive_ring > 0)
1671 		npaths++;
1672 	if (transmit_ring > 0)
1673 		npaths++;
1674 
1675 	if (WARN_ON(!npaths))
1676 		return NULL;
1677 
1678 	tunnel = tb_tunnel_alloc(tb, npaths, TB_TUNNEL_DMA);
1679 	if (!tunnel)
1680 		return NULL;
1681 
1682 	tunnel->src_port = nhi;
1683 	tunnel->dst_port = dst;
1684 	tunnel->deinit = tb_dma_deinit;
1685 
1686 	credits = min_not_zero(dma_credits, nhi->sw->max_dma_credits);
1687 
1688 	if (receive_ring > 0) {
1689 		path = tb_path_alloc(tb, dst, receive_path, nhi, receive_ring, 0,
1690 				     "DMA RX");
1691 		if (!path)
1692 			goto err_free;
1693 		tunnel->paths[i++] = path;
1694 		if (tb_dma_init_rx_path(path, credits)) {
1695 			tb_tunnel_dbg(tunnel, "not enough buffers for RX path\n");
1696 			goto err_free;
1697 		}
1698 	}
1699 
1700 	if (transmit_ring > 0) {
1701 		path = tb_path_alloc(tb, nhi, transmit_ring, dst, transmit_path, 0,
1702 				     "DMA TX");
1703 		if (!path)
1704 			goto err_free;
1705 		tunnel->paths[i++] = path;
1706 		if (tb_dma_init_tx_path(path, credits)) {
1707 			tb_tunnel_dbg(tunnel, "not enough buffers for TX path\n");
1708 			goto err_free;
1709 		}
1710 	}
1711 
1712 	return tunnel;
1713 
1714 err_free:
1715 	tb_tunnel_free(tunnel);
1716 	return NULL;
1717 }
1718 
1719 /**
1720  * tb_tunnel_match_dma() - Match DMA tunnel
1721  * @tunnel: Tunnel to match
1722  * @transmit_path: HopID used for transmitting packets. Pass %-1 to ignore.
1723  * @transmit_ring: NHI ring number used to send packets towards the
1724  *		   other domain. Pass %-1 to ignore.
1725  * @receive_path: HopID used for receiving packets. Pass %-1 to ignore.
1726  * @receive_ring: NHI ring number used to receive packets from the
1727  *		  other domain. Pass %-1 to ignore.
1728  *
1729  * This function can be used to match specific DMA tunnel, if there are
1730  * multiple DMA tunnels going through the same XDomain connection.
1731  * Returns true if there is match and false otherwise.
1732  */
1733 bool tb_tunnel_match_dma(const struct tb_tunnel *tunnel, int transmit_path,
1734 			 int transmit_ring, int receive_path, int receive_ring)
1735 {
1736 	const struct tb_path *tx_path = NULL, *rx_path = NULL;
1737 	int i;
1738 
1739 	if (!receive_ring || !transmit_ring)
1740 		return false;
1741 
1742 	for (i = 0; i < tunnel->npaths; i++) {
1743 		const struct tb_path *path = tunnel->paths[i];
1744 
1745 		if (!path)
1746 			continue;
1747 
1748 		if (tb_port_is_nhi(path->hops[0].in_port))
1749 			tx_path = path;
1750 		else if (tb_port_is_nhi(path->hops[path->path_length - 1].out_port))
1751 			rx_path = path;
1752 	}
1753 
1754 	if (transmit_ring > 0 || transmit_path > 0) {
1755 		if (!tx_path)
1756 			return false;
1757 		if (transmit_ring > 0 &&
1758 		    (tx_path->hops[0].in_hop_index != transmit_ring))
1759 			return false;
1760 		if (transmit_path > 0 &&
1761 		    (tx_path->hops[tx_path->path_length - 1].next_hop_index != transmit_path))
1762 			return false;
1763 	}
1764 
1765 	if (receive_ring > 0 || receive_path > 0) {
1766 		if (!rx_path)
1767 			return false;
1768 		if (receive_path > 0 &&
1769 		    (rx_path->hops[0].in_hop_index != receive_path))
1770 			return false;
1771 		if (receive_ring > 0 &&
1772 		    (rx_path->hops[rx_path->path_length - 1].next_hop_index != receive_ring))
1773 			return false;
1774 	}
1775 
1776 	return true;
1777 }
1778 
1779 static int tb_usb3_max_link_rate(struct tb_port *up, struct tb_port *down)
1780 {
1781 	int ret, up_max_rate, down_max_rate;
1782 
1783 	ret = usb4_usb3_port_max_link_rate(up);
1784 	if (ret < 0)
1785 		return ret;
1786 	up_max_rate = ret;
1787 
1788 	ret = usb4_usb3_port_max_link_rate(down);
1789 	if (ret < 0)
1790 		return ret;
1791 	down_max_rate = ret;
1792 
1793 	return min(up_max_rate, down_max_rate);
1794 }
1795 
1796 static int tb_usb3_init(struct tb_tunnel *tunnel)
1797 {
1798 	tb_tunnel_dbg(tunnel, "allocating initial bandwidth %d/%d Mb/s\n",
1799 		      tunnel->allocated_up, tunnel->allocated_down);
1800 
1801 	return usb4_usb3_port_allocate_bandwidth(tunnel->src_port,
1802 						 &tunnel->allocated_up,
1803 						 &tunnel->allocated_down);
1804 }
1805 
1806 static int tb_usb3_activate(struct tb_tunnel *tunnel, bool activate)
1807 {
1808 	int res;
1809 
1810 	res = tb_usb3_port_enable(tunnel->src_port, activate);
1811 	if (res)
1812 		return res;
1813 
1814 	if (tb_port_is_usb3_up(tunnel->dst_port))
1815 		return tb_usb3_port_enable(tunnel->dst_port, activate);
1816 
1817 	return 0;
1818 }
1819 
1820 static int tb_usb3_consumed_bandwidth(struct tb_tunnel *tunnel,
1821 		int *consumed_up, int *consumed_down)
1822 {
1823 	struct tb_port *port = tb_upstream_port(tunnel->dst_port->sw);
1824 	int pcie_weight = tb_acpi_may_tunnel_pcie() ? TB_PCI_WEIGHT : 0;
1825 
1826 	/*
1827 	 * PCIe tunneling, if enabled, affects the USB3 bandwidth so
1828 	 * take that it into account here.
1829 	 */
1830 	*consumed_up = tunnel->allocated_up *
1831 		(TB_USB3_WEIGHT + pcie_weight) / TB_USB3_WEIGHT;
1832 	*consumed_down = tunnel->allocated_down *
1833 		(TB_USB3_WEIGHT + pcie_weight) / TB_USB3_WEIGHT;
1834 
1835 	if (tb_port_get_link_generation(port) >= 4) {
1836 		*consumed_up = max(*consumed_up, USB4_V2_USB3_MIN_BANDWIDTH);
1837 		*consumed_down = max(*consumed_down, USB4_V2_USB3_MIN_BANDWIDTH);
1838 	}
1839 
1840 	return 0;
1841 }
1842 
1843 static int tb_usb3_release_unused_bandwidth(struct tb_tunnel *tunnel)
1844 {
1845 	int ret;
1846 
1847 	ret = usb4_usb3_port_release_bandwidth(tunnel->src_port,
1848 					       &tunnel->allocated_up,
1849 					       &tunnel->allocated_down);
1850 	if (ret)
1851 		return ret;
1852 
1853 	tb_tunnel_dbg(tunnel, "decreased bandwidth allocation to %d/%d Mb/s\n",
1854 		      tunnel->allocated_up, tunnel->allocated_down);
1855 	return 0;
1856 }
1857 
1858 static void tb_usb3_reclaim_available_bandwidth(struct tb_tunnel *tunnel,
1859 						int *available_up,
1860 						int *available_down)
1861 {
1862 	int ret, max_rate, allocate_up, allocate_down;
1863 
1864 	ret = tb_usb3_max_link_rate(tunnel->dst_port, tunnel->src_port);
1865 	if (ret < 0) {
1866 		tb_tunnel_warn(tunnel, "failed to read maximum link rate\n");
1867 		return;
1868 	}
1869 
1870 	/*
1871 	 * 90% of the max rate can be allocated for isochronous
1872 	 * transfers.
1873 	 */
1874 	max_rate = ret * 90 / 100;
1875 
1876 	/* No need to reclaim if already at maximum */
1877 	if (tunnel->allocated_up >= max_rate &&
1878 	    tunnel->allocated_down >= max_rate)
1879 		return;
1880 
1881 	/* Don't go lower than what is already allocated */
1882 	allocate_up = min(max_rate, *available_up);
1883 	if (allocate_up < tunnel->allocated_up)
1884 		allocate_up = tunnel->allocated_up;
1885 
1886 	allocate_down = min(max_rate, *available_down);
1887 	if (allocate_down < tunnel->allocated_down)
1888 		allocate_down = tunnel->allocated_down;
1889 
1890 	/* If no changes no need to do more */
1891 	if (allocate_up == tunnel->allocated_up &&
1892 	    allocate_down == tunnel->allocated_down)
1893 		return;
1894 
1895 	ret = usb4_usb3_port_allocate_bandwidth(tunnel->src_port, &allocate_up,
1896 						&allocate_down);
1897 	if (ret) {
1898 		tb_tunnel_info(tunnel, "failed to allocate bandwidth\n");
1899 		return;
1900 	}
1901 
1902 	tunnel->allocated_up = allocate_up;
1903 	*available_up -= tunnel->allocated_up;
1904 
1905 	tunnel->allocated_down = allocate_down;
1906 	*available_down -= tunnel->allocated_down;
1907 
1908 	tb_tunnel_dbg(tunnel, "increased bandwidth allocation to %d/%d Mb/s\n",
1909 		      tunnel->allocated_up, tunnel->allocated_down);
1910 }
1911 
1912 static void tb_usb3_init_credits(struct tb_path_hop *hop)
1913 {
1914 	struct tb_port *port = hop->in_port;
1915 	struct tb_switch *sw = port->sw;
1916 	unsigned int credits;
1917 
1918 	if (tb_port_use_credit_allocation(port)) {
1919 		credits = sw->max_usb3_credits;
1920 	} else {
1921 		if (tb_port_is_null(port))
1922 			credits = port->bonded ? 32 : 16;
1923 		else
1924 			credits = 7;
1925 	}
1926 
1927 	hop->initial_credits = credits;
1928 }
1929 
1930 static void tb_usb3_init_path(struct tb_path *path)
1931 {
1932 	struct tb_path_hop *hop;
1933 
1934 	path->egress_fc_enable = TB_PATH_SOURCE | TB_PATH_INTERNAL;
1935 	path->egress_shared_buffer = TB_PATH_NONE;
1936 	path->ingress_fc_enable = TB_PATH_ALL;
1937 	path->ingress_shared_buffer = TB_PATH_NONE;
1938 	path->priority = TB_USB3_PRIORITY;
1939 	path->weight = TB_USB3_WEIGHT;
1940 	path->drop_packages = 0;
1941 
1942 	tb_path_for_each_hop(path, hop)
1943 		tb_usb3_init_credits(hop);
1944 }
1945 
1946 /**
1947  * tb_tunnel_discover_usb3() - Discover existing USB3 tunnels
1948  * @tb: Pointer to the domain structure
1949  * @down: USB3 downstream adapter
1950  * @alloc_hopid: Allocate HopIDs from visited ports
1951  *
1952  * If @down adapter is active, follows the tunnel to the USB3 upstream
1953  * adapter and back. Returns the discovered tunnel or %NULL if there was
1954  * no tunnel.
1955  */
1956 struct tb_tunnel *tb_tunnel_discover_usb3(struct tb *tb, struct tb_port *down,
1957 					  bool alloc_hopid)
1958 {
1959 	struct tb_tunnel *tunnel;
1960 	struct tb_path *path;
1961 
1962 	if (!tb_usb3_port_is_enabled(down))
1963 		return NULL;
1964 
1965 	tunnel = tb_tunnel_alloc(tb, 2, TB_TUNNEL_USB3);
1966 	if (!tunnel)
1967 		return NULL;
1968 
1969 	tunnel->activate = tb_usb3_activate;
1970 	tunnel->src_port = down;
1971 
1972 	/*
1973 	 * Discover both paths even if they are not complete. We will
1974 	 * clean them up by calling tb_tunnel_deactivate() below in that
1975 	 * case.
1976 	 */
1977 	path = tb_path_discover(down, TB_USB3_HOPID, NULL, -1,
1978 				&tunnel->dst_port, "USB3 Down", alloc_hopid);
1979 	if (!path) {
1980 		/* Just disable the downstream port */
1981 		tb_usb3_port_enable(down, false);
1982 		goto err_free;
1983 	}
1984 	tunnel->paths[TB_USB3_PATH_DOWN] = path;
1985 	tb_usb3_init_path(tunnel->paths[TB_USB3_PATH_DOWN]);
1986 
1987 	path = tb_path_discover(tunnel->dst_port, -1, down, TB_USB3_HOPID, NULL,
1988 				"USB3 Up", alloc_hopid);
1989 	if (!path)
1990 		goto err_deactivate;
1991 	tunnel->paths[TB_USB3_PATH_UP] = path;
1992 	tb_usb3_init_path(tunnel->paths[TB_USB3_PATH_UP]);
1993 
1994 	/* Validate that the tunnel is complete */
1995 	if (!tb_port_is_usb3_up(tunnel->dst_port)) {
1996 		tb_port_warn(tunnel->dst_port,
1997 			     "path does not end on an USB3 adapter, cleaning up\n");
1998 		goto err_deactivate;
1999 	}
2000 
2001 	if (down != tunnel->src_port) {
2002 		tb_tunnel_warn(tunnel, "path is not complete, cleaning up\n");
2003 		goto err_deactivate;
2004 	}
2005 
2006 	if (!tb_usb3_port_is_enabled(tunnel->dst_port)) {
2007 		tb_tunnel_warn(tunnel,
2008 			       "tunnel is not fully activated, cleaning up\n");
2009 		goto err_deactivate;
2010 	}
2011 
2012 	if (!tb_route(down->sw)) {
2013 		int ret;
2014 
2015 		/*
2016 		 * Read the initial bandwidth allocation for the first
2017 		 * hop tunnel.
2018 		 */
2019 		ret = usb4_usb3_port_allocated_bandwidth(down,
2020 			&tunnel->allocated_up, &tunnel->allocated_down);
2021 		if (ret)
2022 			goto err_deactivate;
2023 
2024 		tb_tunnel_dbg(tunnel, "currently allocated bandwidth %d/%d Mb/s\n",
2025 			      tunnel->allocated_up, tunnel->allocated_down);
2026 
2027 		tunnel->init = tb_usb3_init;
2028 		tunnel->consumed_bandwidth = tb_usb3_consumed_bandwidth;
2029 		tunnel->release_unused_bandwidth =
2030 			tb_usb3_release_unused_bandwidth;
2031 		tunnel->reclaim_available_bandwidth =
2032 			tb_usb3_reclaim_available_bandwidth;
2033 	}
2034 
2035 	tb_tunnel_dbg(tunnel, "discovered\n");
2036 	return tunnel;
2037 
2038 err_deactivate:
2039 	tb_tunnel_deactivate(tunnel);
2040 err_free:
2041 	tb_tunnel_free(tunnel);
2042 
2043 	return NULL;
2044 }
2045 
2046 /**
2047  * tb_tunnel_alloc_usb3() - allocate a USB3 tunnel
2048  * @tb: Pointer to the domain structure
2049  * @up: USB3 upstream adapter port
2050  * @down: USB3 downstream adapter port
2051  * @max_up: Maximum available upstream bandwidth for the USB3 tunnel.
2052  *	    %0 if no available bandwidth.
2053  * @max_down: Maximum available downstream bandwidth for the USB3 tunnel.
2054  *	      %0 if no available bandwidth.
2055  *
2056  * Allocate an USB3 tunnel. The ports must be of type @TB_TYPE_USB3_UP and
2057  * @TB_TYPE_USB3_DOWN.
2058  *
2059  * Return: Returns a tb_tunnel on success or %NULL on failure.
2060  */
2061 struct tb_tunnel *tb_tunnel_alloc_usb3(struct tb *tb, struct tb_port *up,
2062 				       struct tb_port *down, int max_up,
2063 				       int max_down)
2064 {
2065 	struct tb_tunnel *tunnel;
2066 	struct tb_path *path;
2067 	int max_rate = 0;
2068 
2069 	if (!tb_route(down->sw) && (max_up > 0 || max_down > 0)) {
2070 		/*
2071 		 * For USB3 isochronous transfers, we allow bandwidth which is
2072 		 * not higher than 90% of maximum supported bandwidth by USB3
2073 		 * adapters.
2074 		 */
2075 		max_rate = tb_usb3_max_link_rate(down, up);
2076 		if (max_rate < 0)
2077 			return NULL;
2078 
2079 		max_rate = max_rate * 90 / 100;
2080 		tb_port_dbg(up, "maximum required bandwidth for USB3 tunnel %d Mb/s\n",
2081 			    max_rate);
2082 	}
2083 
2084 	tunnel = tb_tunnel_alloc(tb, 2, TB_TUNNEL_USB3);
2085 	if (!tunnel)
2086 		return NULL;
2087 
2088 	tunnel->activate = tb_usb3_activate;
2089 	tunnel->src_port = down;
2090 	tunnel->dst_port = up;
2091 	tunnel->max_up = max_up;
2092 	tunnel->max_down = max_down;
2093 
2094 	path = tb_path_alloc(tb, down, TB_USB3_HOPID, up, TB_USB3_HOPID, 0,
2095 			     "USB3 Down");
2096 	if (!path) {
2097 		tb_tunnel_free(tunnel);
2098 		return NULL;
2099 	}
2100 	tb_usb3_init_path(path);
2101 	tunnel->paths[TB_USB3_PATH_DOWN] = path;
2102 
2103 	path = tb_path_alloc(tb, up, TB_USB3_HOPID, down, TB_USB3_HOPID, 0,
2104 			     "USB3 Up");
2105 	if (!path) {
2106 		tb_tunnel_free(tunnel);
2107 		return NULL;
2108 	}
2109 	tb_usb3_init_path(path);
2110 	tunnel->paths[TB_USB3_PATH_UP] = path;
2111 
2112 	if (!tb_route(down->sw)) {
2113 		tunnel->allocated_up = min(max_rate, max_up);
2114 		tunnel->allocated_down = min(max_rate, max_down);
2115 
2116 		tunnel->init = tb_usb3_init;
2117 		tunnel->consumed_bandwidth = tb_usb3_consumed_bandwidth;
2118 		tunnel->release_unused_bandwidth =
2119 			tb_usb3_release_unused_bandwidth;
2120 		tunnel->reclaim_available_bandwidth =
2121 			tb_usb3_reclaim_available_bandwidth;
2122 	}
2123 
2124 	return tunnel;
2125 }
2126 
2127 /**
2128  * tb_tunnel_free() - free a tunnel
2129  * @tunnel: Tunnel to be freed
2130  *
2131  * Frees a tunnel. The tunnel does not need to be deactivated.
2132  */
2133 void tb_tunnel_free(struct tb_tunnel *tunnel)
2134 {
2135 	int i;
2136 
2137 	if (!tunnel)
2138 		return;
2139 
2140 	if (tunnel->deinit)
2141 		tunnel->deinit(tunnel);
2142 
2143 	for (i = 0; i < tunnel->npaths; i++) {
2144 		if (tunnel->paths[i])
2145 			tb_path_free(tunnel->paths[i]);
2146 	}
2147 
2148 	kfree(tunnel->paths);
2149 	kfree(tunnel);
2150 }
2151 
2152 /**
2153  * tb_tunnel_is_invalid - check whether an activated path is still valid
2154  * @tunnel: Tunnel to check
2155  */
2156 bool tb_tunnel_is_invalid(struct tb_tunnel *tunnel)
2157 {
2158 	int i;
2159 
2160 	for (i = 0; i < tunnel->npaths; i++) {
2161 		WARN_ON(!tunnel->paths[i]->activated);
2162 		if (tb_path_is_invalid(tunnel->paths[i]))
2163 			return true;
2164 	}
2165 
2166 	return false;
2167 }
2168 
2169 /**
2170  * tb_tunnel_restart() - activate a tunnel after a hardware reset
2171  * @tunnel: Tunnel to restart
2172  *
2173  * Return: 0 on success and negative errno in case if failure
2174  */
2175 int tb_tunnel_restart(struct tb_tunnel *tunnel)
2176 {
2177 	int res, i;
2178 
2179 	tb_tunnel_dbg(tunnel, "activating\n");
2180 
2181 	/*
2182 	 * Make sure all paths are properly disabled before enabling
2183 	 * them again.
2184 	 */
2185 	for (i = 0; i < tunnel->npaths; i++) {
2186 		if (tunnel->paths[i]->activated) {
2187 			tb_path_deactivate(tunnel->paths[i]);
2188 			tunnel->paths[i]->activated = false;
2189 		}
2190 	}
2191 
2192 	if (tunnel->init) {
2193 		res = tunnel->init(tunnel);
2194 		if (res)
2195 			return res;
2196 	}
2197 
2198 	for (i = 0; i < tunnel->npaths; i++) {
2199 		res = tb_path_activate(tunnel->paths[i]);
2200 		if (res)
2201 			goto err;
2202 	}
2203 
2204 	if (tunnel->activate) {
2205 		res = tunnel->activate(tunnel, true);
2206 		if (res)
2207 			goto err;
2208 	}
2209 
2210 	return 0;
2211 
2212 err:
2213 	tb_tunnel_warn(tunnel, "activation failed\n");
2214 	tb_tunnel_deactivate(tunnel);
2215 	return res;
2216 }
2217 
2218 /**
2219  * tb_tunnel_activate() - activate a tunnel
2220  * @tunnel: Tunnel to activate
2221  *
2222  * Return: Returns 0 on success or an error code on failure.
2223  */
2224 int tb_tunnel_activate(struct tb_tunnel *tunnel)
2225 {
2226 	int i;
2227 
2228 	for (i = 0; i < tunnel->npaths; i++) {
2229 		if (tunnel->paths[i]->activated) {
2230 			tb_tunnel_WARN(tunnel,
2231 				       "trying to activate an already activated tunnel\n");
2232 			return -EINVAL;
2233 		}
2234 	}
2235 
2236 	return tb_tunnel_restart(tunnel);
2237 }
2238 
2239 /**
2240  * tb_tunnel_deactivate() - deactivate a tunnel
2241  * @tunnel: Tunnel to deactivate
2242  */
2243 void tb_tunnel_deactivate(struct tb_tunnel *tunnel)
2244 {
2245 	int i;
2246 
2247 	tb_tunnel_dbg(tunnel, "deactivating\n");
2248 
2249 	if (tunnel->activate)
2250 		tunnel->activate(tunnel, false);
2251 
2252 	for (i = 0; i < tunnel->npaths; i++) {
2253 		if (tunnel->paths[i] && tunnel->paths[i]->activated)
2254 			tb_path_deactivate(tunnel->paths[i]);
2255 	}
2256 }
2257 
2258 /**
2259  * tb_tunnel_port_on_path() - Does the tunnel go through port
2260  * @tunnel: Tunnel to check
2261  * @port: Port to check
2262  *
2263  * Returns true if @tunnel goes through @port (direction does not matter),
2264  * false otherwise.
2265  */
2266 bool tb_tunnel_port_on_path(const struct tb_tunnel *tunnel,
2267 			    const struct tb_port *port)
2268 {
2269 	int i;
2270 
2271 	for (i = 0; i < tunnel->npaths; i++) {
2272 		if (!tunnel->paths[i])
2273 			continue;
2274 
2275 		if (tb_path_port_on_path(tunnel->paths[i], port))
2276 			return true;
2277 	}
2278 
2279 	return false;
2280 }
2281 
2282 static bool tb_tunnel_is_active(const struct tb_tunnel *tunnel)
2283 {
2284 	int i;
2285 
2286 	for (i = 0; i < tunnel->npaths; i++) {
2287 		if (!tunnel->paths[i])
2288 			return false;
2289 		if (!tunnel->paths[i]->activated)
2290 			return false;
2291 	}
2292 
2293 	return true;
2294 }
2295 
2296 /**
2297  * tb_tunnel_maximum_bandwidth() - Return maximum possible bandwidth
2298  * @tunnel: Tunnel to check
2299  * @max_up: Maximum upstream bandwidth in Mb/s
2300  * @max_down: Maximum downstream bandwidth in Mb/s
2301  *
2302  * Returns maximum possible bandwidth this tunnel can go if not limited
2303  * by other bandwidth clients. If the tunnel does not support this
2304  * returns %-EOPNOTSUPP.
2305  */
2306 int tb_tunnel_maximum_bandwidth(struct tb_tunnel *tunnel, int *max_up,
2307 				int *max_down)
2308 {
2309 	if (!tb_tunnel_is_active(tunnel))
2310 		return -EINVAL;
2311 
2312 	if (tunnel->maximum_bandwidth)
2313 		return tunnel->maximum_bandwidth(tunnel, max_up, max_down);
2314 	return -EOPNOTSUPP;
2315 }
2316 
2317 /**
2318  * tb_tunnel_allocated_bandwidth() - Return bandwidth allocated for the tunnel
2319  * @tunnel: Tunnel to check
2320  * @allocated_up: Currently allocated upstream bandwidth in Mb/s is stored here
2321  * @allocated_down: Currently allocated downstream bandwidth in Mb/s is
2322  *		    stored here
2323  *
2324  * Returns the bandwidth allocated for the tunnel. This may be higher
2325  * than what the tunnel actually consumes.
2326  */
2327 int tb_tunnel_allocated_bandwidth(struct tb_tunnel *tunnel, int *allocated_up,
2328 				  int *allocated_down)
2329 {
2330 	if (!tb_tunnel_is_active(tunnel))
2331 		return -EINVAL;
2332 
2333 	if (tunnel->allocated_bandwidth)
2334 		return tunnel->allocated_bandwidth(tunnel, allocated_up,
2335 						   allocated_down);
2336 	return -EOPNOTSUPP;
2337 }
2338 
2339 /**
2340  * tb_tunnel_alloc_bandwidth() - Change tunnel bandwidth allocation
2341  * @tunnel: Tunnel whose bandwidth allocation to change
2342  * @alloc_up: New upstream bandwidth in Mb/s
2343  * @alloc_down: New downstream bandwidth in Mb/s
2344  *
2345  * Tries to change tunnel bandwidth allocation. If succeeds returns %0
2346  * and updates @alloc_up and @alloc_down to that was actually allocated
2347  * (it may not be the same as passed originally). Returns negative errno
2348  * in case of failure.
2349  */
2350 int tb_tunnel_alloc_bandwidth(struct tb_tunnel *tunnel, int *alloc_up,
2351 			      int *alloc_down)
2352 {
2353 	if (!tb_tunnel_is_active(tunnel))
2354 		return -EINVAL;
2355 
2356 	if (tunnel->alloc_bandwidth)
2357 		return tunnel->alloc_bandwidth(tunnel, alloc_up, alloc_down);
2358 
2359 	return -EOPNOTSUPP;
2360 }
2361 
2362 /**
2363  * tb_tunnel_consumed_bandwidth() - Return bandwidth consumed by the tunnel
2364  * @tunnel: Tunnel to check
2365  * @consumed_up: Consumed bandwidth in Mb/s from @dst_port to @src_port.
2366  *		 Can be %NULL.
2367  * @consumed_down: Consumed bandwidth in Mb/s from @src_port to @dst_port.
2368  *		   Can be %NULL.
2369  *
2370  * Stores the amount of isochronous bandwidth @tunnel consumes in
2371  * @consumed_up and @consumed_down. In case of success returns %0,
2372  * negative errno otherwise.
2373  */
2374 int tb_tunnel_consumed_bandwidth(struct tb_tunnel *tunnel, int *consumed_up,
2375 				 int *consumed_down)
2376 {
2377 	int up_bw = 0, down_bw = 0;
2378 
2379 	if (!tb_tunnel_is_active(tunnel))
2380 		goto out;
2381 
2382 	if (tunnel->consumed_bandwidth) {
2383 		int ret;
2384 
2385 		ret = tunnel->consumed_bandwidth(tunnel, &up_bw, &down_bw);
2386 		if (ret)
2387 			return ret;
2388 
2389 		tb_tunnel_dbg(tunnel, "consumed bandwidth %d/%d Mb/s\n", up_bw,
2390 			      down_bw);
2391 	}
2392 
2393 out:
2394 	if (consumed_up)
2395 		*consumed_up = up_bw;
2396 	if (consumed_down)
2397 		*consumed_down = down_bw;
2398 
2399 	return 0;
2400 }
2401 
2402 /**
2403  * tb_tunnel_release_unused_bandwidth() - Release unused bandwidth
2404  * @tunnel: Tunnel whose unused bandwidth to release
2405  *
2406  * If tunnel supports dynamic bandwidth management (USB3 tunnels at the
2407  * moment) this function makes it to release all the unused bandwidth.
2408  *
2409  * Returns %0 in case of success and negative errno otherwise.
2410  */
2411 int tb_tunnel_release_unused_bandwidth(struct tb_tunnel *tunnel)
2412 {
2413 	if (!tb_tunnel_is_active(tunnel))
2414 		return 0;
2415 
2416 	if (tunnel->release_unused_bandwidth) {
2417 		int ret;
2418 
2419 		ret = tunnel->release_unused_bandwidth(tunnel);
2420 		if (ret)
2421 			return ret;
2422 	}
2423 
2424 	return 0;
2425 }
2426 
2427 /**
2428  * tb_tunnel_reclaim_available_bandwidth() - Reclaim available bandwidth
2429  * @tunnel: Tunnel reclaiming available bandwidth
2430  * @available_up: Available upstream bandwidth (in Mb/s)
2431  * @available_down: Available downstream bandwidth (in Mb/s)
2432  *
2433  * Reclaims bandwidth from @available_up and @available_down and updates
2434  * the variables accordingly (e.g decreases both according to what was
2435  * reclaimed by the tunnel). If nothing was reclaimed the values are
2436  * kept as is.
2437  */
2438 void tb_tunnel_reclaim_available_bandwidth(struct tb_tunnel *tunnel,
2439 					   int *available_up,
2440 					   int *available_down)
2441 {
2442 	if (!tb_tunnel_is_active(tunnel))
2443 		return;
2444 
2445 	if (tunnel->reclaim_available_bandwidth)
2446 		tunnel->reclaim_available_bandwidth(tunnel, available_up,
2447 						    available_down);
2448 }
2449 
2450 const char *tb_tunnel_type_name(const struct tb_tunnel *tunnel)
2451 {
2452 	return tb_tunnel_names[tunnel->type];
2453 }
2454