// SPDX-License-Identifier: GPL-2.0

  /*

   * Thunderbolt driver - Tunneling support

   *
   * Copyright (c) 2014 Andreas Noever <andreas.noever@gmail.com>

   * Copyright (C) 2019, Intel Corporation

   */

  #include <linux/delay.h>

  #include <linux/slab.h>
  #include <linux/list.h>

  #include "tunnel.h"

  #include "tb.h"

  /* PCIe adapters use always HopID of 8 for both directions */
  #define TB_PCI_HOPID			8

  #define TB_PCI_PATH_DOWN		0
  #define TB_PCI_PATH_UP			1

  /* USB3 adapters use always HopID of 8 for both directions */
  #define TB_USB3_HOPID			8
  
  #define TB_USB3_PATH_DOWN		0
  #define TB_USB3_PATH_UP			1

  /* DP adapters use HopID 8 for AUX and 9 for Video */
  #define TB_DP_AUX_TX_HOPID		8
  #define TB_DP_AUX_RX_HOPID		8
  #define TB_DP_VIDEO_HOPID		9
  
  #define TB_DP_VIDEO_PATH_OUT		0
  #define TB_DP_AUX_PATH_OUT		1
  #define TB_DP_AUX_PATH_IN		2

  #define TB_DMA_PATH_OUT			0
  #define TB_DMA_PATH_IN			1

  static const char * const tb_tunnel_names[] = { "PCI", "DP", "DMA", "USB3" };

  #define __TB_TUNNEL_PRINT(level, tunnel, fmt, arg...)                   \
  	do {                                                            \

  		struct tb_tunnel *__tunnel = (tunnel);                  \

  		level(__tunnel->tb, "%llx:%x <-> %llx:%x (%s): " fmt,   \

  		      tb_route(__tunnel->src_port->sw),                 \
  		      __tunnel->src_port->port,                         \
  		      tb_route(__tunnel->dst_port->sw),                 \
  		      __tunnel->dst_port->port,                         \

  		      tb_tunnel_names[__tunnel->type],			\

  		      ## arg);                                          \
  	} while (0)
  
  #define tb_tunnel_WARN(tunnel, fmt, arg...) \
  	__TB_TUNNEL_PRINT(tb_WARN, tunnel, fmt, ##arg)
  #define tb_tunnel_warn(tunnel, fmt, arg...) \
  	__TB_TUNNEL_PRINT(tb_warn, tunnel, fmt, ##arg)
  #define tb_tunnel_info(tunnel, fmt, arg...) \
  	__TB_TUNNEL_PRINT(tb_info, tunnel, fmt, ##arg)

  #define tb_tunnel_dbg(tunnel, fmt, arg...) \
  	__TB_TUNNEL_PRINT(tb_dbg, tunnel, fmt, ##arg)

  static struct tb_tunnel *tb_tunnel_alloc(struct tb *tb, size_t npaths,
  					 enum tb_tunnel_type type)

  {
  	struct tb_tunnel *tunnel;
  
  	tunnel = kzalloc(sizeof(*tunnel), GFP_KERNEL);
  	if (!tunnel)
  		return NULL;
  
  	tunnel->paths = kcalloc(npaths, sizeof(tunnel->paths[0]), GFP_KERNEL);
  	if (!tunnel->paths) {
  		tb_tunnel_free(tunnel);
  		return NULL;
  	}
  
  	INIT_LIST_HEAD(&tunnel->list);
  	tunnel->tb = tb;
  	tunnel->npaths = npaths;

  	tunnel->type = type;

  
  	return tunnel;
  }
  
  static int tb_pci_activate(struct tb_tunnel *tunnel, bool activate)
  {
  	int res;
  
  	res = tb_pci_port_enable(tunnel->src_port, activate);
  	if (res)
  		return res;

  	if (tb_port_is_pcie_up(tunnel->dst_port))
  		return tb_pci_port_enable(tunnel->dst_port, activate);
  
  	return 0;

  }

  static int tb_initial_credits(const struct tb_switch *sw)
  {
  	/* If the path is complete sw is not NULL */
  	if (sw) {
  		/* More credits for faster link */
  		switch (sw->link_speed * sw->link_width) {
  		case 40:
  			return 32;
  		case 20:
  			return 24;
  		}
  	}
  
  	return 16;
  }

  static void tb_pci_init_path(struct tb_path *path)
  {
  	path->egress_fc_enable = TB_PATH_SOURCE | TB_PATH_INTERNAL;
  	path->egress_shared_buffer = TB_PATH_NONE;
  	path->ingress_fc_enable = TB_PATH_ALL;
  	path->ingress_shared_buffer = TB_PATH_NONE;
  	path->priority = 3;
  	path->weight = 1;
  	path->drop_packages = 0;
  	path->nfc_credits = 0;

  	path->hops[0].initial_credits = 7;

  	if (path->path_length > 1)
  		path->hops[1].initial_credits =
  			tb_initial_credits(path->hops[1].in_port->sw);

  }
  
  /**
   * tb_tunnel_discover_pci() - Discover existing PCIe tunnels
   * @tb: Pointer to the domain structure
   * @down: PCIe downstream adapter
   *
   * If @down adapter is active, follows the tunnel to the PCIe upstream
   * adapter and back. Returns the discovered tunnel or %NULL if there was
   * no tunnel.
   */
  struct tb_tunnel *tb_tunnel_discover_pci(struct tb *tb, struct tb_port *down)
  {
  	struct tb_tunnel *tunnel;
  	struct tb_path *path;
  
  	if (!tb_pci_port_is_enabled(down))
  		return NULL;

  	tunnel = tb_tunnel_alloc(tb, 2, TB_TUNNEL_PCI);

  	if (!tunnel)
  		return NULL;
  
  	tunnel->activate = tb_pci_activate;
  	tunnel->src_port = down;
  
  	/*
  	 * Discover both paths even if they are not complete. We will
  	 * clean them up by calling tb_tunnel_deactivate() below in that
  	 * case.
  	 */
  	path = tb_path_discover(down, TB_PCI_HOPID, NULL, -1,
  				&tunnel->dst_port, "PCIe Up");
  	if (!path) {
  		/* Just disable the downstream port */
  		tb_pci_port_enable(down, false);
  		goto err_free;
  	}
  	tunnel->paths[TB_PCI_PATH_UP] = path;
  	tb_pci_init_path(tunnel->paths[TB_PCI_PATH_UP]);
  
  	path = tb_path_discover(tunnel->dst_port, -1, down, TB_PCI_HOPID, NULL,
  				"PCIe Down");
  	if (!path)
  		goto err_deactivate;
  	tunnel->paths[TB_PCI_PATH_DOWN] = path;
  	tb_pci_init_path(tunnel->paths[TB_PCI_PATH_DOWN]);
  
  	/* Validate that the tunnel is complete */
  	if (!tb_port_is_pcie_up(tunnel->dst_port)) {
  		tb_port_warn(tunnel->dst_port,
  			     "path does not end on a PCIe adapter, cleaning up
  ");
  		goto err_deactivate;
  	}
  
  	if (down != tunnel->src_port) {
  		tb_tunnel_warn(tunnel, "path is not complete, cleaning up
  ");
  		goto err_deactivate;
  	}
  
  	if (!tb_pci_port_is_enabled(tunnel->dst_port)) {
  		tb_tunnel_warn(tunnel,
  			       "tunnel is not fully activated, cleaning up
  ");
  		goto err_deactivate;
  	}
  
  	tb_tunnel_dbg(tunnel, "discovered
  ");
  	return tunnel;
  
  err_deactivate:
  	tb_tunnel_deactivate(tunnel);
  err_free:
  	tb_tunnel_free(tunnel);
  
  	return NULL;

  }
  
  /**

   * tb_tunnel_alloc_pci() - allocate a pci tunnel
   * @tb: Pointer to the domain structure
   * @up: PCIe upstream adapter port
   * @down: PCIe downstream adapter port

   *
   * Allocate a PCI tunnel. The ports must be of type TB_TYPE_PCIE_UP and
   * TB_TYPE_PCIE_DOWN.
   *

   * Return: Returns a tb_tunnel on success or NULL on failure.

   */

  struct tb_tunnel *tb_tunnel_alloc_pci(struct tb *tb, struct tb_port *up,
  				      struct tb_port *down)

  {

  	struct tb_tunnel *tunnel;

  	struct tb_path *path;

  	tunnel = tb_tunnel_alloc(tb, 2, TB_TUNNEL_PCI);

  	if (!tunnel)

  		return NULL;

  	tunnel->activate = tb_pci_activate;
  	tunnel->src_port = down;
  	tunnel->dst_port = up;

  	path = tb_path_alloc(tb, down, TB_PCI_HOPID, up, TB_PCI_HOPID, 0,
  			     "PCIe Down");
  	if (!path) {

  		tb_tunnel_free(tunnel);
  		return NULL;

  	}

  	tb_pci_init_path(path);

  	tunnel->paths[TB_PCI_PATH_DOWN] = path;

  	path = tb_path_alloc(tb, up, TB_PCI_HOPID, down, TB_PCI_HOPID, 0,
  			     "PCIe Up");
  	if (!path) {

  		tb_tunnel_free(tunnel);
  		return NULL;
  	}

  	tb_pci_init_path(path);

  	tunnel->paths[TB_PCI_PATH_UP] = path;

  
  	return tunnel;

  }

  static bool tb_dp_is_usb4(const struct tb_switch *sw)
  {
  	/* Titan Ridge DP adapters need the same treatment as USB4 */
  	return tb_switch_is_usb4(sw) || tb_switch_is_titan_ridge(sw);
  }

  static int tb_dp_cm_handshake(struct tb_port *in, struct tb_port *out)
  {
  	int timeout = 10;
  	u32 val;
  	int ret;
  
  	/* Both ends need to support this */

  	if (!tb_dp_is_usb4(in->sw) || !tb_dp_is_usb4(out->sw))

  		return 0;
  
  	ret = tb_port_read(out, &val, TB_CFG_PORT,
  			   out->cap_adap + DP_STATUS_CTRL, 1);
  	if (ret)
  		return ret;
  
  	val |= DP_STATUS_CTRL_UF | DP_STATUS_CTRL_CMHS;
  
  	ret = tb_port_write(out, &val, TB_CFG_PORT,
  			    out->cap_adap + DP_STATUS_CTRL, 1);
  	if (ret)
  		return ret;
  
  	do {
  		ret = tb_port_read(out, &val, TB_CFG_PORT,
  				   out->cap_adap + DP_STATUS_CTRL, 1);
  		if (ret)
  			return ret;
  		if (!(val & DP_STATUS_CTRL_CMHS))
  			return 0;
  		usleep_range(10, 100);
  	} while (timeout--);
  
  	return -ETIMEDOUT;
  }

  static inline u32 tb_dp_cap_get_rate(u32 val)
  {
  	u32 rate = (val & DP_COMMON_CAP_RATE_MASK) >> DP_COMMON_CAP_RATE_SHIFT;
  
  	switch (rate) {
  	case DP_COMMON_CAP_RATE_RBR:
  		return 1620;
  	case DP_COMMON_CAP_RATE_HBR:
  		return 2700;
  	case DP_COMMON_CAP_RATE_HBR2:
  		return 5400;
  	case DP_COMMON_CAP_RATE_HBR3:
  		return 8100;
  	default:
  		return 0;
  	}
  }
  
  static inline u32 tb_dp_cap_set_rate(u32 val, u32 rate)
  {
  	val &= ~DP_COMMON_CAP_RATE_MASK;
  	switch (rate) {
  	default:
  		WARN(1, "invalid rate %u passed, defaulting to 1620 MB/s
  ", rate);

  		fallthrough;

  	case 1620:
  		val |= DP_COMMON_CAP_RATE_RBR << DP_COMMON_CAP_RATE_SHIFT;
  		break;
  	case 2700:
  		val |= DP_COMMON_CAP_RATE_HBR << DP_COMMON_CAP_RATE_SHIFT;
  		break;
  	case 5400:
  		val |= DP_COMMON_CAP_RATE_HBR2 << DP_COMMON_CAP_RATE_SHIFT;
  		break;
  	case 8100:
  		val |= DP_COMMON_CAP_RATE_HBR3 << DP_COMMON_CAP_RATE_SHIFT;
  		break;
  	}
  	return val;
  }
  
  static inline u32 tb_dp_cap_get_lanes(u32 val)
  {
  	u32 lanes = (val & DP_COMMON_CAP_LANES_MASK) >> DP_COMMON_CAP_LANES_SHIFT;
  
  	switch (lanes) {
  	case DP_COMMON_CAP_1_LANE:
  		return 1;
  	case DP_COMMON_CAP_2_LANES:
  		return 2;
  	case DP_COMMON_CAP_4_LANES:
  		return 4;
  	default:
  		return 0;
  	}
  }
  
  static inline u32 tb_dp_cap_set_lanes(u32 val, u32 lanes)
  {
  	val &= ~DP_COMMON_CAP_LANES_MASK;
  	switch (lanes) {
  	default:
  		WARN(1, "invalid number of lanes %u passed, defaulting to 1
  ",
  		     lanes);

  		fallthrough;

  	case 1:
  		val |= DP_COMMON_CAP_1_LANE << DP_COMMON_CAP_LANES_SHIFT;
  		break;
  	case 2:
  		val |= DP_COMMON_CAP_2_LANES << DP_COMMON_CAP_LANES_SHIFT;
  		break;
  	case 4:
  		val |= DP_COMMON_CAP_4_LANES << DP_COMMON_CAP_LANES_SHIFT;
  		break;
  	}
  	return val;
  }
  
  static unsigned int tb_dp_bandwidth(unsigned int rate, unsigned int lanes)
  {
  	/* Tunneling removes the DP 8b/10b encoding */
  	return rate * lanes * 8 / 10;
  }
  
  static int tb_dp_reduce_bandwidth(int max_bw, u32 in_rate, u32 in_lanes,
  				  u32 out_rate, u32 out_lanes, u32 *new_rate,
  				  u32 *new_lanes)
  {
  	static const u32 dp_bw[][2] = {
  		/* Mb/s, lanes */
  		{ 8100, 4 }, /* 25920 Mb/s */
  		{ 5400, 4 }, /* 17280 Mb/s */
  		{ 8100, 2 }, /* 12960 Mb/s */
  		{ 2700, 4 }, /* 8640 Mb/s */
  		{ 5400, 2 }, /* 8640 Mb/s */
  		{ 8100, 1 }, /* 6480 Mb/s */
  		{ 1620, 4 }, /* 5184 Mb/s */
  		{ 5400, 1 }, /* 4320 Mb/s */
  		{ 2700, 2 }, /* 4320 Mb/s */
  		{ 1620, 2 }, /* 2592 Mb/s */
  		{ 2700, 1 }, /* 2160 Mb/s */
  		{ 1620, 1 }, /* 1296 Mb/s */
  	};
  	unsigned int i;
  
  	/*
  	 * Find a combination that can fit into max_bw and does not
  	 * exceed the maximum rate and lanes supported by the DP OUT and
  	 * DP IN adapters.
  	 */
  	for (i = 0; i < ARRAY_SIZE(dp_bw); i++) {
  		if (dp_bw[i][0] > out_rate || dp_bw[i][1] > out_lanes)
  			continue;
  
  		if (dp_bw[i][0] > in_rate || dp_bw[i][1] > in_lanes)
  			continue;
  
  		if (tb_dp_bandwidth(dp_bw[i][0], dp_bw[i][1]) <= max_bw) {
  			*new_rate = dp_bw[i][0];
  			*new_lanes = dp_bw[i][1];
  			return 0;
  		}
  	}
  
  	return -ENOSR;
  }

  static int tb_dp_xchg_caps(struct tb_tunnel *tunnel)
  {

  	u32 out_dp_cap, out_rate, out_lanes, in_dp_cap, in_rate, in_lanes, bw;

  	struct tb_port *out = tunnel->dst_port;
  	struct tb_port *in = tunnel->src_port;

  	int ret, max_bw;

  
  	/*
  	 * Copy DP_LOCAL_CAP register to DP_REMOTE_CAP register for
  	 * newer generation hardware.
  	 */
  	if (in->sw->generation < 2 || out->sw->generation < 2)
  		return 0;

  	/*
  	 * Perform connection manager handshake between IN and OUT ports
  	 * before capabilities exchange can take place.
  	 */
  	ret = tb_dp_cm_handshake(in, out);
  	if (ret)
  		return ret;

  	/* Read both DP_LOCAL_CAP registers */
  	ret = tb_port_read(in, &in_dp_cap, TB_CFG_PORT,

  			   in->cap_adap + DP_LOCAL_CAP, 1);

  	if (ret)
  		return ret;
  
  	ret = tb_port_read(out, &out_dp_cap, TB_CFG_PORT,

  			   out->cap_adap + DP_LOCAL_CAP, 1);

  	if (ret)
  		return ret;
  
  	/* Write IN local caps to OUT remote caps */
  	ret = tb_port_write(out, &in_dp_cap, TB_CFG_PORT,

  			    out->cap_adap + DP_REMOTE_CAP, 1);

  	if (ret)
  		return ret;

  	in_rate = tb_dp_cap_get_rate(in_dp_cap);
  	in_lanes = tb_dp_cap_get_lanes(in_dp_cap);
  	tb_port_dbg(in, "maximum supported bandwidth %u Mb/s x%u = %u Mb/s
  ",
  		    in_rate, in_lanes, tb_dp_bandwidth(in_rate, in_lanes));
  
  	/*
  	 * If the tunnel bandwidth is limited (max_bw is set) then see
  	 * if we need to reduce bandwidth to fit there.
  	 */
  	out_rate = tb_dp_cap_get_rate(out_dp_cap);
  	out_lanes = tb_dp_cap_get_lanes(out_dp_cap);
  	bw = tb_dp_bandwidth(out_rate, out_lanes);
  	tb_port_dbg(out, "maximum supported bandwidth %u Mb/s x%u = %u Mb/s
  ",
  		    out_rate, out_lanes, bw);

  	if (in->sw->config.depth < out->sw->config.depth)
  		max_bw = tunnel->max_down;
  	else
  		max_bw = tunnel->max_up;
  
  	if (max_bw && bw > max_bw) {

  		u32 new_rate, new_lanes, new_bw;

  		ret = tb_dp_reduce_bandwidth(max_bw, in_rate, in_lanes,

  					     out_rate, out_lanes, &new_rate,
  					     &new_lanes);
  		if (ret) {
  			tb_port_info(out, "not enough bandwidth for DP tunnel
  ");
  			return ret;
  		}
  
  		new_bw = tb_dp_bandwidth(new_rate, new_lanes);
  		tb_port_dbg(out, "bandwidth reduced to %u Mb/s x%u = %u Mb/s
  ",
  			    new_rate, new_lanes, new_bw);
  
  		/*
  		 * Set new rate and number of lanes before writing it to
  		 * the IN port remote caps.
  		 */
  		out_dp_cap = tb_dp_cap_set_rate(out_dp_cap, new_rate);
  		out_dp_cap = tb_dp_cap_set_lanes(out_dp_cap, new_lanes);
  	}

  	return tb_port_write(in, &out_dp_cap, TB_CFG_PORT,

  			     in->cap_adap + DP_REMOTE_CAP, 1);

  }
  
  static int tb_dp_activate(struct tb_tunnel *tunnel, bool active)
  {
  	int ret;
  
  	if (active) {
  		struct tb_path **paths;
  		int last;
  
  		paths = tunnel->paths;
  		last = paths[TB_DP_VIDEO_PATH_OUT]->path_length - 1;
  
  		tb_dp_port_set_hops(tunnel->src_port,
  			paths[TB_DP_VIDEO_PATH_OUT]->hops[0].in_hop_index,
  			paths[TB_DP_AUX_PATH_OUT]->hops[0].in_hop_index,
  			paths[TB_DP_AUX_PATH_IN]->hops[last].next_hop_index);
  
  		tb_dp_port_set_hops(tunnel->dst_port,
  			paths[TB_DP_VIDEO_PATH_OUT]->hops[last].next_hop_index,
  			paths[TB_DP_AUX_PATH_IN]->hops[0].in_hop_index,
  			paths[TB_DP_AUX_PATH_OUT]->hops[last].next_hop_index);
  	} else {
  		tb_dp_port_hpd_clear(tunnel->src_port);
  		tb_dp_port_set_hops(tunnel->src_port, 0, 0, 0);
  		if (tb_port_is_dpout(tunnel->dst_port))
  			tb_dp_port_set_hops(tunnel->dst_port, 0, 0, 0);
  	}
  
  	ret = tb_dp_port_enable(tunnel->src_port, active);
  	if (ret)
  		return ret;
  
  	if (tb_port_is_dpout(tunnel->dst_port))
  		return tb_dp_port_enable(tunnel->dst_port, active);
  
  	return 0;
  }

  static int tb_dp_consumed_bandwidth(struct tb_tunnel *tunnel, int *consumed_up,
  				    int *consumed_down)

  {
  	struct tb_port *in = tunnel->src_port;
  	const struct tb_switch *sw = in->sw;
  	u32 val, rate = 0, lanes = 0;
  	int ret;

  	if (tb_dp_is_usb4(sw)) {

  		int timeout = 20;

  
  		/*
  		 * Wait for DPRX done. Normally it should be already set
  		 * for active tunnel.
  		 */
  		do {
  			ret = tb_port_read(in, &val, TB_CFG_PORT,
  					   in->cap_adap + DP_COMMON_CAP, 1);
  			if (ret)
  				return ret;
  
  			if (val & DP_COMMON_CAP_DPRX_DONE) {
  				rate = tb_dp_cap_get_rate(val);
  				lanes = tb_dp_cap_get_lanes(val);
  				break;
  			}
  			msleep(250);
  		} while (timeout--);
  
  		if (!timeout)
  			return -ETIMEDOUT;
  	} else if (sw->generation >= 2) {
  		/*
  		 * Read from the copied remote cap so that we take into
  		 * account if capabilities were reduced during exchange.
  		 */
  		ret = tb_port_read(in, &val, TB_CFG_PORT,
  				   in->cap_adap + DP_REMOTE_CAP, 1);
  		if (ret)
  			return ret;
  
  		rate = tb_dp_cap_get_rate(val);
  		lanes = tb_dp_cap_get_lanes(val);
  	} else {
  		/* No bandwidth management for legacy devices  */

  		*consumed_up = 0;
  		*consumed_down = 0;

  		return 0;
  	}

  	if (in->sw->config.depth < tunnel->dst_port->sw->config.depth) {
  		*consumed_up = 0;
  		*consumed_down = tb_dp_bandwidth(rate, lanes);
  	} else {
  		*consumed_up = tb_dp_bandwidth(rate, lanes);
  		*consumed_down = 0;
  	}
  
  	return 0;

  }

  static void tb_dp_init_aux_path(struct tb_path *path)
  {
  	int i;
  
  	path->egress_fc_enable = TB_PATH_SOURCE | TB_PATH_INTERNAL;
  	path->egress_shared_buffer = TB_PATH_NONE;
  	path->ingress_fc_enable = TB_PATH_ALL;
  	path->ingress_shared_buffer = TB_PATH_NONE;
  	path->priority = 2;
  	path->weight = 1;
  
  	for (i = 0; i < path->path_length; i++)
  		path->hops[i].initial_credits = 1;
  }
  
  static void tb_dp_init_video_path(struct tb_path *path, bool discover)
  {
  	u32 nfc_credits = path->hops[0].in_port->config.nfc_credits;
  
  	path->egress_fc_enable = TB_PATH_NONE;
  	path->egress_shared_buffer = TB_PATH_NONE;
  	path->ingress_fc_enable = TB_PATH_NONE;
  	path->ingress_shared_buffer = TB_PATH_NONE;
  	path->priority = 1;
  	path->weight = 1;
  
  	if (discover) {

  		path->nfc_credits = nfc_credits & ADP_CS_4_NFC_BUFFERS_MASK;

  	} else {
  		u32 max_credits;

  		max_credits = (nfc_credits & ADP_CS_4_TOTAL_BUFFERS_MASK) >>
  			ADP_CS_4_TOTAL_BUFFERS_SHIFT;

  		/* Leave some credits for AUX path */
  		path->nfc_credits = min(max_credits - 2, 12U);
  	}
  }
  
  /**
   * tb_tunnel_discover_dp() - Discover existing Display Port tunnels
   * @tb: Pointer to the domain structure
   * @in: DP in adapter
   *
   * If @in adapter is active, follows the tunnel to the DP out adapter
   * and back. Returns the discovered tunnel or %NULL if there was no
   * tunnel.
   *
   * Return: DP tunnel or %NULL if no tunnel found.
   */
  struct tb_tunnel *tb_tunnel_discover_dp(struct tb *tb, struct tb_port *in)
  {
  	struct tb_tunnel *tunnel;
  	struct tb_port *port;
  	struct tb_path *path;
  
  	if (!tb_dp_port_is_enabled(in))
  		return NULL;
  
  	tunnel = tb_tunnel_alloc(tb, 3, TB_TUNNEL_DP);
  	if (!tunnel)
  		return NULL;
  
  	tunnel->init = tb_dp_xchg_caps;
  	tunnel->activate = tb_dp_activate;

  	tunnel->consumed_bandwidth = tb_dp_consumed_bandwidth;

  	tunnel->src_port = in;
  
  	path = tb_path_discover(in, TB_DP_VIDEO_HOPID, NULL, -1,
  				&tunnel->dst_port, "Video");
  	if (!path) {
  		/* Just disable the DP IN port */
  		tb_dp_port_enable(in, false);
  		goto err_free;
  	}
  	tunnel->paths[TB_DP_VIDEO_PATH_OUT] = path;
  	tb_dp_init_video_path(tunnel->paths[TB_DP_VIDEO_PATH_OUT], true);
  
  	path = tb_path_discover(in, TB_DP_AUX_TX_HOPID, NULL, -1, NULL, "AUX TX");
  	if (!path)
  		goto err_deactivate;
  	tunnel->paths[TB_DP_AUX_PATH_OUT] = path;
  	tb_dp_init_aux_path(tunnel->paths[TB_DP_AUX_PATH_OUT]);
  
  	path = tb_path_discover(tunnel->dst_port, -1, in, TB_DP_AUX_RX_HOPID,
  				&port, "AUX RX");
  	if (!path)
  		goto err_deactivate;
  	tunnel->paths[TB_DP_AUX_PATH_IN] = path;
  	tb_dp_init_aux_path(tunnel->paths[TB_DP_AUX_PATH_IN]);
  
  	/* Validate that the tunnel is complete */
  	if (!tb_port_is_dpout(tunnel->dst_port)) {
  		tb_port_warn(in, "path does not end on a DP adapter, cleaning up
  ");
  		goto err_deactivate;
  	}
  
  	if (!tb_dp_port_is_enabled(tunnel->dst_port))
  		goto err_deactivate;
  
  	if (!tb_dp_port_hpd_is_active(tunnel->dst_port))
  		goto err_deactivate;
  
  	if (port != tunnel->src_port) {
  		tb_tunnel_warn(tunnel, "path is not complete, cleaning up
  ");
  		goto err_deactivate;
  	}
  
  	tb_tunnel_dbg(tunnel, "discovered
  ");
  	return tunnel;
  
  err_deactivate:
  	tb_tunnel_deactivate(tunnel);
  err_free:
  	tb_tunnel_free(tunnel);
  
  	return NULL;
  }
  
  /**
   * tb_tunnel_alloc_dp() - allocate a Display Port tunnel
   * @tb: Pointer to the domain structure
   * @in: DP in adapter port
   * @out: DP out adapter port

   * @max_up: Maximum available upstream bandwidth for the DP tunnel (%0
   *	    if not limited)
   * @max_down: Maximum available downstream bandwidth for the DP tunnel
   *	      (%0 if not limited)

   *
   * Allocates a tunnel between @in and @out that is capable of tunneling
   * Display Port traffic.
   *
   * Return: Returns a tb_tunnel on success or NULL on failure.
   */
  struct tb_tunnel *tb_tunnel_alloc_dp(struct tb *tb, struct tb_port *in,

  				     struct tb_port *out, int max_up,
  				     int max_down)

  {
  	struct tb_tunnel *tunnel;
  	struct tb_path **paths;
  	struct tb_path *path;
  
  	if (WARN_ON(!in->cap_adap || !out->cap_adap))
  		return NULL;
  
  	tunnel = tb_tunnel_alloc(tb, 3, TB_TUNNEL_DP);
  	if (!tunnel)
  		return NULL;
  
  	tunnel->init = tb_dp_xchg_caps;
  	tunnel->activate = tb_dp_activate;

  	tunnel->consumed_bandwidth = tb_dp_consumed_bandwidth;

  	tunnel->src_port = in;
  	tunnel->dst_port = out;

  	tunnel->max_up = max_up;
  	tunnel->max_down = max_down;

  
  	paths = tunnel->paths;
  
  	path = tb_path_alloc(tb, in, TB_DP_VIDEO_HOPID, out, TB_DP_VIDEO_HOPID,
  			     1, "Video");
  	if (!path)
  		goto err_free;
  	tb_dp_init_video_path(path, false);
  	paths[TB_DP_VIDEO_PATH_OUT] = path;
  
  	path = tb_path_alloc(tb, in, TB_DP_AUX_TX_HOPID, out,
  			     TB_DP_AUX_TX_HOPID, 1, "AUX TX");
  	if (!path)
  		goto err_free;
  	tb_dp_init_aux_path(path);
  	paths[TB_DP_AUX_PATH_OUT] = path;
  
  	path = tb_path_alloc(tb, out, TB_DP_AUX_RX_HOPID, in,
  			     TB_DP_AUX_RX_HOPID, 1, "AUX RX");
  	if (!path)
  		goto err_free;
  	tb_dp_init_aux_path(path);
  	paths[TB_DP_AUX_PATH_IN] = path;
  
  	return tunnel;
  
  err_free:
  	tb_tunnel_free(tunnel);
  	return NULL;
  }

  static u32 tb_dma_credits(struct tb_port *nhi)
  {
  	u32 max_credits;

  	max_credits = (nhi->config.nfc_credits & ADP_CS_4_TOTAL_BUFFERS_MASK) >>
  		ADP_CS_4_TOTAL_BUFFERS_SHIFT;

  	return min(max_credits, 13U);
  }
  
  static int tb_dma_activate(struct tb_tunnel *tunnel, bool active)
  {
  	struct tb_port *nhi = tunnel->src_port;
  	u32 credits;
  
  	credits = active ? tb_dma_credits(nhi) : 0;
  	return tb_port_set_initial_credits(nhi, credits);
  }
  
  static void tb_dma_init_path(struct tb_path *path, unsigned int isb,
  			     unsigned int efc, u32 credits)
  {
  	int i;
  
  	path->egress_fc_enable = efc;
  	path->ingress_fc_enable = TB_PATH_ALL;
  	path->egress_shared_buffer = TB_PATH_NONE;
  	path->ingress_shared_buffer = isb;
  	path->priority = 5;
  	path->weight = 1;
  	path->clear_fc = true;
  
  	for (i = 0; i < path->path_length; i++)
  		path->hops[i].initial_credits = credits;
  }
  
  /**
   * tb_tunnel_alloc_dma() - allocate a DMA tunnel
   * @tb: Pointer to the domain structure
   * @nhi: Host controller port
   * @dst: Destination null port which the other domain is connected to
   * @transmit_ring: NHI ring number used to send packets towards the
   *		   other domain
   * @transmit_path: HopID used for transmitting packets
   * @receive_ring: NHI ring number used to receive packets from the
   *		  other domain
   * @reveive_path: HopID used for receiving packets
   *
   * Return: Returns a tb_tunnel on success or NULL on failure.
   */
  struct tb_tunnel *tb_tunnel_alloc_dma(struct tb *tb, struct tb_port *nhi,
  				      struct tb_port *dst, int transmit_ring,
  				      int transmit_path, int receive_ring,
  				      int receive_path)
  {
  	struct tb_tunnel *tunnel;
  	struct tb_path *path;
  	u32 credits;
  
  	tunnel = tb_tunnel_alloc(tb, 2, TB_TUNNEL_DMA);
  	if (!tunnel)
  		return NULL;
  
  	tunnel->activate = tb_dma_activate;
  	tunnel->src_port = nhi;
  	tunnel->dst_port = dst;
  
  	credits = tb_dma_credits(nhi);
  
  	path = tb_path_alloc(tb, dst, receive_path, nhi, receive_ring, 0, "DMA RX");
  	if (!path) {
  		tb_tunnel_free(tunnel);
  		return NULL;
  	}
  	tb_dma_init_path(path, TB_PATH_NONE, TB_PATH_SOURCE | TB_PATH_INTERNAL,
  			 credits);
  	tunnel->paths[TB_DMA_PATH_IN] = path;
  
  	path = tb_path_alloc(tb, nhi, transmit_ring, dst, transmit_path, 0, "DMA TX");
  	if (!path) {
  		tb_tunnel_free(tunnel);
  		return NULL;
  	}
  	tb_dma_init_path(path, TB_PATH_SOURCE, TB_PATH_ALL, credits);
  	tunnel->paths[TB_DMA_PATH_OUT] = path;
  
  	return tunnel;
  }

  static int tb_usb3_max_link_rate(struct tb_port *up, struct tb_port *down)
  {
  	int ret, up_max_rate, down_max_rate;
  
  	ret = usb4_usb3_port_max_link_rate(up);
  	if (ret < 0)
  		return ret;
  	up_max_rate = ret;
  
  	ret = usb4_usb3_port_max_link_rate(down);
  	if (ret < 0)
  		return ret;
  	down_max_rate = ret;
  
  	return min(up_max_rate, down_max_rate);
  }
  
  static int tb_usb3_init(struct tb_tunnel *tunnel)
  {
  	tb_tunnel_dbg(tunnel, "allocating initial bandwidth %d/%d Mb/s
  ",
  		      tunnel->allocated_up, tunnel->allocated_down);
  
  	return usb4_usb3_port_allocate_bandwidth(tunnel->src_port,
  						 &tunnel->allocated_up,
  						 &tunnel->allocated_down);
  }

  static int tb_usb3_activate(struct tb_tunnel *tunnel, bool activate)
  {
  	int res;
  
  	res = tb_usb3_port_enable(tunnel->src_port, activate);
  	if (res)
  		return res;
  
  	if (tb_port_is_usb3_up(tunnel->dst_port))
  		return tb_usb3_port_enable(tunnel->dst_port, activate);
  
  	return 0;
  }

  static int tb_usb3_consumed_bandwidth(struct tb_tunnel *tunnel,
  		int *consumed_up, int *consumed_down)
  {
  	/*
  	 * PCIe tunneling affects the USB3 bandwidth so take that it
  	 * into account here.
  	 */
  	*consumed_up = tunnel->allocated_up * (3 + 1) / 3;
  	*consumed_down = tunnel->allocated_down * (3 + 1) / 3;
  	return 0;
  }
  
  static int tb_usb3_release_unused_bandwidth(struct tb_tunnel *tunnel)
  {
  	int ret;
  
  	ret = usb4_usb3_port_release_bandwidth(tunnel->src_port,
  					       &tunnel->allocated_up,
  					       &tunnel->allocated_down);
  	if (ret)
  		return ret;
  
  	tb_tunnel_dbg(tunnel, "decreased bandwidth allocation to %d/%d Mb/s
  ",
  		      tunnel->allocated_up, tunnel->allocated_down);
  	return 0;
  }
  
  static void tb_usb3_reclaim_available_bandwidth(struct tb_tunnel *tunnel,
  						int *available_up,
  						int *available_down)
  {
  	int ret, max_rate, allocate_up, allocate_down;
  
  	ret = usb4_usb3_port_actual_link_rate(tunnel->src_port);

  	if (ret < 0) {
  		tb_tunnel_warn(tunnel, "failed to read actual link rate
  ");

  		return;

  	} else if (!ret) {
  		/* Use maximum link rate if the link valid is not set */
  		ret = usb4_usb3_port_max_link_rate(tunnel->src_port);
  		if (ret < 0) {
  			tb_tunnel_warn(tunnel, "failed to read maximum link rate
  ");
  			return;
  		}

  	}

  	/*
  	 * 90% of the max rate can be allocated for isochronous
  	 * transfers.
  	 */
  	max_rate = ret * 90 / 100;
  
  	/* No need to reclaim if already at maximum */
  	if (tunnel->allocated_up >= max_rate &&
  	    tunnel->allocated_down >= max_rate)
  		return;
  
  	/* Don't go lower than what is already allocated */
  	allocate_up = min(max_rate, *available_up);
  	if (allocate_up < tunnel->allocated_up)
  		allocate_up = tunnel->allocated_up;
  
  	allocate_down = min(max_rate, *available_down);
  	if (allocate_down < tunnel->allocated_down)
  		allocate_down = tunnel->allocated_down;
  
  	/* If no changes no need to do more */
  	if (allocate_up == tunnel->allocated_up &&
  	    allocate_down == tunnel->allocated_down)
  		return;
  
  	ret = usb4_usb3_port_allocate_bandwidth(tunnel->src_port, &allocate_up,
  						&allocate_down);
  	if (ret) {
  		tb_tunnel_info(tunnel, "failed to allocate bandwidth
  ");
  		return;
  	}
  
  	tunnel->allocated_up = allocate_up;
  	*available_up -= tunnel->allocated_up;
  
  	tunnel->allocated_down = allocate_down;
  	*available_down -= tunnel->allocated_down;
  
  	tb_tunnel_dbg(tunnel, "increased bandwidth allocation to %d/%d Mb/s
  ",
  		      tunnel->allocated_up, tunnel->allocated_down);
  }

  static void tb_usb3_init_path(struct tb_path *path)
  {
  	path->egress_fc_enable = TB_PATH_SOURCE | TB_PATH_INTERNAL;
  	path->egress_shared_buffer = TB_PATH_NONE;
  	path->ingress_fc_enable = TB_PATH_ALL;
  	path->ingress_shared_buffer = TB_PATH_NONE;
  	path->priority = 3;
  	path->weight = 3;
  	path->drop_packages = 0;
  	path->nfc_credits = 0;
  	path->hops[0].initial_credits = 7;

  	if (path->path_length > 1)
  		path->hops[1].initial_credits =
  			tb_initial_credits(path->hops[1].in_port->sw);

  }
  
  /**
   * tb_tunnel_discover_usb3() - Discover existing USB3 tunnels
   * @tb: Pointer to the domain structure
   * @down: USB3 downstream adapter
   *
   * If @down adapter is active, follows the tunnel to the USB3 upstream
   * adapter and back. Returns the discovered tunnel or %NULL if there was
   * no tunnel.
   */
  struct tb_tunnel *tb_tunnel_discover_usb3(struct tb *tb, struct tb_port *down)
  {
  	struct tb_tunnel *tunnel;
  	struct tb_path *path;
  
  	if (!tb_usb3_port_is_enabled(down))
  		return NULL;
  
  	tunnel = tb_tunnel_alloc(tb, 2, TB_TUNNEL_USB3);
  	if (!tunnel)
  		return NULL;
  
  	tunnel->activate = tb_usb3_activate;
  	tunnel->src_port = down;
  
  	/*
  	 * Discover both paths even if they are not complete. We will
  	 * clean them up by calling tb_tunnel_deactivate() below in that
  	 * case.
  	 */
  	path = tb_path_discover(down, TB_USB3_HOPID, NULL, -1,

  				&tunnel->dst_port, "USB3 Down");

  	if (!path) {
  		/* Just disable the downstream port */
  		tb_usb3_port_enable(down, false);
  		goto err_free;
  	}

  	tunnel->paths[TB_USB3_PATH_DOWN] = path;
  	tb_usb3_init_path(tunnel->paths[TB_USB3_PATH_DOWN]);

  
  	path = tb_path_discover(tunnel->dst_port, -1, down, TB_USB3_HOPID, NULL,

  				"USB3 Up");

  	if (!path)
  		goto err_deactivate;

  	tunnel->paths[TB_USB3_PATH_UP] = path;
  	tb_usb3_init_path(tunnel->paths[TB_USB3_PATH_UP]);

  
  	/* Validate that the tunnel is complete */
  	if (!tb_port_is_usb3_up(tunnel->dst_port)) {
  		tb_port_warn(tunnel->dst_port,
  			     "path does not end on an USB3 adapter, cleaning up
  ");
  		goto err_deactivate;
  	}
  
  	if (down != tunnel->src_port) {
  		tb_tunnel_warn(tunnel, "path is not complete, cleaning up
  ");
  		goto err_deactivate;
  	}
  
  	if (!tb_usb3_port_is_enabled(tunnel->dst_port)) {
  		tb_tunnel_warn(tunnel,
  			       "tunnel is not fully activated, cleaning up
  ");
  		goto err_deactivate;
  	}

  	if (!tb_route(down->sw)) {
  		int ret;
  
  		/*
  		 * Read the initial bandwidth allocation for the first
  		 * hop tunnel.
  		 */
  		ret = usb4_usb3_port_allocated_bandwidth(down,
  			&tunnel->allocated_up, &tunnel->allocated_down);
  		if (ret)
  			goto err_deactivate;
  
  		tb_tunnel_dbg(tunnel, "currently allocated bandwidth %d/%d Mb/s
  ",
  			      tunnel->allocated_up, tunnel->allocated_down);
  
  		tunnel->init = tb_usb3_init;
  		tunnel->consumed_bandwidth = tb_usb3_consumed_bandwidth;
  		tunnel->release_unused_bandwidth =
  			tb_usb3_release_unused_bandwidth;
  		tunnel->reclaim_available_bandwidth =
  			tb_usb3_reclaim_available_bandwidth;
  	}

  	tb_tunnel_dbg(tunnel, "discovered
  ");
  	return tunnel;
  
  err_deactivate:
  	tb_tunnel_deactivate(tunnel);
  err_free:
  	tb_tunnel_free(tunnel);
  
  	return NULL;
  }
  
  /**
   * tb_tunnel_alloc_usb3() - allocate a USB3 tunnel
   * @tb: Pointer to the domain structure
   * @up: USB3 upstream adapter port
   * @down: USB3 downstream adapter port

   * @max_up: Maximum available upstream bandwidth for the USB3 tunnel (%0
   *	    if not limited).
   * @max_down: Maximum available downstream bandwidth for the USB3 tunnel
   *	      (%0 if not limited).

   *
   * Allocate an USB3 tunnel. The ports must be of type @TB_TYPE_USB3_UP and
   * @TB_TYPE_USB3_DOWN.
   *
   * Return: Returns a tb_tunnel on success or %NULL on failure.
   */
  struct tb_tunnel *tb_tunnel_alloc_usb3(struct tb *tb, struct tb_port *up,

  				       struct tb_port *down, int max_up,
  				       int max_down)

  {
  	struct tb_tunnel *tunnel;
  	struct tb_path *path;

  	int max_rate = 0;
  
  	/*
  	 * Check that we have enough bandwidth available for the new
  	 * USB3 tunnel.
  	 */
  	if (max_up > 0 || max_down > 0) {
  		max_rate = tb_usb3_max_link_rate(down, up);
  		if (max_rate < 0)
  			return NULL;
  
  		/* Only 90% can be allocated for USB3 isochronous transfers */
  		max_rate = max_rate * 90 / 100;
  		tb_port_dbg(up, "required bandwidth for USB3 tunnel %d Mb/s
  ",
  			    max_rate);
  
  		if (max_rate > max_up || max_rate > max_down) {
  			tb_port_warn(up, "not enough bandwidth for USB3 tunnel
  ");
  			return NULL;
  		}
  	}

  
  	tunnel = tb_tunnel_alloc(tb, 2, TB_TUNNEL_USB3);
  	if (!tunnel)
  		return NULL;
  
  	tunnel->activate = tb_usb3_activate;
  	tunnel->src_port = down;
  	tunnel->dst_port = up;

  	tunnel->max_up = max_up;
  	tunnel->max_down = max_down;

  
  	path = tb_path_alloc(tb, down, TB_USB3_HOPID, up, TB_USB3_HOPID, 0,
  			     "USB3 Down");
  	if (!path) {
  		tb_tunnel_free(tunnel);
  		return NULL;
  	}
  	tb_usb3_init_path(path);
  	tunnel->paths[TB_USB3_PATH_DOWN] = path;
  
  	path = tb_path_alloc(tb, up, TB_USB3_HOPID, down, TB_USB3_HOPID, 0,
  			     "USB3 Up");
  	if (!path) {
  		tb_tunnel_free(tunnel);
  		return NULL;
  	}
  	tb_usb3_init_path(path);
  	tunnel->paths[TB_USB3_PATH_UP] = path;

  	if (!tb_route(down->sw)) {
  		tunnel->allocated_up = max_rate;
  		tunnel->allocated_down = max_rate;
  
  		tunnel->init = tb_usb3_init;
  		tunnel->consumed_bandwidth = tb_usb3_consumed_bandwidth;
  		tunnel->release_unused_bandwidth =
  			tb_usb3_release_unused_bandwidth;
  		tunnel->reclaim_available_bandwidth =
  			tb_usb3_reclaim_available_bandwidth;
  	}

  	return tunnel;
  }

  /**

   * tb_tunnel_free() - free a tunnel
   * @tunnel: Tunnel to be freed

   *

   * Frees a tunnel. The tunnel does not need to be deactivated.

   */

  void tb_tunnel_free(struct tb_tunnel *tunnel)

  {

  	int i;
  
  	if (!tunnel)

  		return;

  
  	for (i = 0; i < tunnel->npaths; i++) {

  		if (tunnel->paths[i])
  			tb_path_free(tunnel->paths[i]);
  	}
  
  	kfree(tunnel->paths);

  	kfree(tunnel);
  }
  
  /**

   * tb_tunnel_is_invalid - check whether an activated path is still valid
   * @tunnel: Tunnel to check

   */

  bool tb_tunnel_is_invalid(struct tb_tunnel *tunnel)

  {

  	int i;

  	for (i = 0; i < tunnel->npaths; i++) {
  		WARN_ON(!tunnel->paths[i]->activated);
  		if (tb_path_is_invalid(tunnel->paths[i]))
  			return true;
  	}

  	return false;

  }
  
  /**

   * tb_tunnel_restart() - activate a tunnel after a hardware reset
   * @tunnel: Tunnel to restart
   *
   * Return: 0 on success and negative errno in case if failure

   */

  int tb_tunnel_restart(struct tb_tunnel *tunnel)

  {

  	int res, i;

  	tb_tunnel_dbg(tunnel, "activating
  ");

  	/*
  	 * Make sure all paths are properly disabled before enabling
  	 * them again.
  	 */
  	for (i = 0; i < tunnel->npaths; i++) {
  		if (tunnel->paths[i]->activated) {
  			tb_path_deactivate(tunnel->paths[i]);
  			tunnel->paths[i]->activated = false;
  		}
  	}

  	if (tunnel->init) {
  		res = tunnel->init(tunnel);
  		if (res)
  			return res;
  	}

  	for (i = 0; i < tunnel->npaths; i++) {

  		res = tb_path_activate(tunnel->paths[i]);
  		if (res)
  			goto err;
  	}

  	if (tunnel->activate) {
  		res = tunnel->activate(tunnel, true);
  		if (res)
  			goto err;
  	}

  	return 0;

  err:
  	tb_tunnel_warn(tunnel, "activation failed
  ");

  	tb_tunnel_deactivate(tunnel);

  	return res;
  }
  
  /**

   * tb_tunnel_activate() - activate a tunnel
   * @tunnel: Tunnel to activate

   *
   * Return: Returns 0 on success or an error code on failure.
   */

  int tb_tunnel_activate(struct tb_tunnel *tunnel)

  {

  	int i;

  	for (i = 0; i < tunnel->npaths; i++) {
  		if (tunnel->paths[i]->activated) {
  			tb_tunnel_WARN(tunnel,
  				       "trying to activate an already activated tunnel
  ");
  			return -EINVAL;
  		}
  	}

  	return tb_tunnel_restart(tunnel);
  }

  
  /**

   * tb_tunnel_deactivate() - deactivate a tunnel
   * @tunnel: Tunnel to deactivate

   */

  void tb_tunnel_deactivate(struct tb_tunnel *tunnel)

  {

  	int i;

  	tb_tunnel_dbg(tunnel, "deactivating
  ");

  	if (tunnel->activate)
  		tunnel->activate(tunnel, false);
  
  	for (i = 0; i < tunnel->npaths; i++) {

  		if (tunnel->paths[i] && tunnel->paths[i]->activated)

  			tb_path_deactivate(tunnel->paths[i]);
  	}
  }

  
  /**

   * tb_tunnel_port_on_path() - Does the tunnel go through port

   * @tunnel: Tunnel to check

   * @port: Port to check

   *

   * Returns true if @tunnel goes through @port (direction does not matter),

   * false otherwise.
   */

  bool tb_tunnel_port_on_path(const struct tb_tunnel *tunnel,
  			    const struct tb_port *port)

  {
  	int i;
  
  	for (i = 0; i < tunnel->npaths; i++) {
  		if (!tunnel->paths[i])
  			continue;

  
  		if (tb_path_port_on_path(tunnel->paths[i], port))

  			return true;
  	}
  
  	return false;
  }
  
  static bool tb_tunnel_is_active(const struct tb_tunnel *tunnel)
  {
  	int i;
  
  	for (i = 0; i < tunnel->npaths; i++) {
  		if (!tunnel->paths[i])
  			return false;
  		if (!tunnel->paths[i]->activated)
  			return false;
  	}
  
  	return true;
  }
  
  /**
   * tb_tunnel_consumed_bandwidth() - Return bandwidth consumed by the tunnel
   * @tunnel: Tunnel to check

   * @consumed_up: Consumed bandwidth in Mb/s from @dst_port to @src_port.
   *		 Can be %NULL.
   * @consumed_down: Consumed bandwidth in Mb/s from @src_port to @dst_port.
   *		   Can be %NULL.

   *

   * Stores the amount of isochronous bandwidth @tunnel consumes in
   * @consumed_up and @consumed_down. In case of success returns %0,
   * negative errno otherwise.

   */

  int tb_tunnel_consumed_bandwidth(struct tb_tunnel *tunnel, int *consumed_up,
  				 int *consumed_down)

  {

  	int up_bw = 0, down_bw = 0;

  	if (!tb_tunnel_is_active(tunnel))

  		goto out;

  
  	if (tunnel->consumed_bandwidth) {

  		int ret;

  		ret = tunnel->consumed_bandwidth(tunnel, &up_bw, &down_bw);
  		if (ret)
  			return ret;
  
  		tb_tunnel_dbg(tunnel, "consumed bandwidth %d/%d Mb/s
  ", up_bw,
  			      down_bw);

  	}

  out:
  	if (consumed_up)
  		*consumed_up = up_bw;
  	if (consumed_down)
  		*consumed_down = down_bw;

  	return 0;
  }

  
  /**
   * tb_tunnel_release_unused_bandwidth() - Release unused bandwidth
   * @tunnel: Tunnel whose unused bandwidth to release
   *
   * If tunnel supports dynamic bandwidth management (USB3 tunnels at the
   * moment) this function makes it to release all the unused bandwidth.
   *
   * Returns %0 in case of success and negative errno otherwise.
   */
  int tb_tunnel_release_unused_bandwidth(struct tb_tunnel *tunnel)
  {
  	if (!tb_tunnel_is_active(tunnel))
  		return 0;
  
  	if (tunnel->release_unused_bandwidth) {
  		int ret;
  
  		ret = tunnel->release_unused_bandwidth(tunnel);
  		if (ret)
  			return ret;
  	}
  
  	return 0;
  }
  
  /**
   * tb_tunnel_reclaim_available_bandwidth() - Reclaim available bandwidth
   * @tunnel: Tunnel reclaiming available bandwidth
   * @available_up: Available upstream bandwidth (in Mb/s)
   * @available_down: Available downstream bandwidth (in Mb/s)
   *
   * Reclaims bandwidth from @available_up and @available_down and updates
   * the variables accordingly (e.g decreases both according to what was
   * reclaimed by the tunnel). If nothing was reclaimed the values are
   * kept as is.
   */
  void tb_tunnel_reclaim_available_bandwidth(struct tb_tunnel *tunnel,
  					   int *available_up,
  					   int *available_down)
  {
  	if (!tb_tunnel_is_active(tunnel))
  		return;
  
  	if (tunnel->reclaim_available_bandwidth)
  		tunnel->reclaim_available_bandwidth(tunnel, available_up,
  						    available_down);
  }