drivers/thunderbolt/switch.c - kernel/msm-4.9 - Gitiles

 /*
  * Thunderbolt Cactus Ridge driver - switch/port utility functions
  *
  * Copyright (c) 2014 Andreas Noever <andreas.noever@gmail.com>
  */

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

 #include "tb.h"

 /* port utility functions */

 static const char *tb_port_type(struct tb_regs_port_header *port)
 {
 	switch (port->type >> 16) {
 	case 0:
 		switch ((u8) port->type) {
 		case 0:
 			return "Inactive";
 		case 1:
 			return "Port";
 		case 2:
 			return "NHI";
 		default:
 			return "unknown";
 		}
 	case 0x2:
 		return "Ethernet";
 	case 0x8:
 		return "SATA";
 	case 0xe:
 		return "DP/HDMI";
 	case 0x10:
 		return "PCIe";
 	case 0x20:
 		return "USB";
 	default:
 		return "unknown";
 	}
 }

 static void tb_dump_port(struct tb *tb, struct tb_regs_port_header *port)
 {
 	tb_info(tb,
 		" Port %d: %x:%x (Revision: %d, TB Version: %d, Type: %s (%#x))\n",
 		port->port_number, port->vendor_id, port->device_id,
 		port->revision, port->thunderbolt_version, tb_port_type(port),
 		port->type);
 	tb_info(tb, "  Max hop id (in/out): %d/%d\n",
 		port->max_in_hop_id, port->max_out_hop_id);
 	tb_info(tb, "  Max counters: %d\n", port->max_counters);
 	tb_info(tb, "  NFC Credits: %#x\n", port->nfc_credits);
 }

 /**
  * tb_port_state() - get connectedness state of a port
  *
  * The port must have a TB_CAP_PHY (i.e. it should be a real port).
  *
  * Return: Returns an enum tb_port_state on success or an error code on failure.
  */
 static int tb_port_state(struct tb_port *port)
 {
 	struct tb_cap_phy phy;
 	int res;
 	if (port->cap_phy == 0) {
 		tb_port_WARN(port, "does not have a PHY\n");
 		return -EINVAL;
 	}
 	res = tb_port_read(port, &phy, TB_CFG_PORT, port->cap_phy, 2);
 	if (res)
 		return res;
 	return phy.state;
 }

 /**
  * tb_wait_for_port() - wait for a port to become ready
  *
  * Wait up to 1 second for a port to reach state TB_PORT_UP. If
  * wait_if_unplugged is set then we also wait if the port is in state
  * TB_PORT_UNPLUGGED (it takes a while for the device to be registered after
  * switch resume). Otherwise we only wait if a device is registered but the link
  * has not yet been established.
  *
  * Return: Returns an error code on failure. Returns 0 if the port is not
  * connected or failed to reach state TB_PORT_UP within one second. Returns 1
  * if the port is connected and in state TB_PORT_UP.
  */
 int tb_wait_for_port(struct tb_port *port, bool wait_if_unplugged)
 {
 	int retries = 10;
 	int state;
 	if (!port->cap_phy) {
 		tb_port_WARN(port, "does not have PHY\n");
 		return -EINVAL;
 	}
 	if (tb_is_upstream_port(port)) {
 		tb_port_WARN(port, "is the upstream port\n");
 		return -EINVAL;
 	}

 	while (retries--) {
 		state = tb_port_state(port);
 		if (state < 0)
 			return state;
 		if (state == TB_PORT_DISABLED) {
 			tb_port_info(port, "is disabled (state: 0)\n");
 			return 0;
 		}
 		if (state == TB_PORT_UNPLUGGED) {
 			if (wait_if_unplugged) {
 				/* used during resume */
 				tb_port_info(port,
 					     "is unplugged (state: 7), retrying...\n");
 				msleep(100);
 				continue;
 			}
 			tb_port_info(port, "is unplugged (state: 7)\n");
 			return 0;
 		}
 		if (state == TB_PORT_UP) {
 			tb_port_info(port,
 				     "is connected, link is up (state: 2)\n");
 			return 1;
 		}

 		/*
 		 * After plug-in the state is TB_PORT_CONNECTING. Give it some
 		 * time.
 		 */
 		tb_port_info(port,
 			     "is connected, link is not up (state: %d), retrying...\n",
 			     state);
 		msleep(100);
 	}
 	tb_port_warn(port,
 		     "failed to reach state TB_PORT_UP. Ignoring port...\n");
 	return 0;
 }

 /**
  * tb_port_add_nfc_credits() - add/remove non flow controlled credits to port
  *
  * Change the number of NFC credits allocated to @port by @credits. To remove
  * NFC credits pass a negative amount of credits.
  *
  * Return: Returns 0 on success or an error code on failure.
  */
 int tb_port_add_nfc_credits(struct tb_port *port, int credits)
 {
 	if (credits == 0)
 		return 0;
 	tb_port_info(port,
 		     "adding %#x NFC credits (%#x -> %#x)",
 		     credits,
 		     port->config.nfc_credits,
 		     port->config.nfc_credits + credits);
 	port->config.nfc_credits += credits;
 	return tb_port_write(port, &port->config.nfc_credits,
 			     TB_CFG_PORT, 4, 1);
 }

 /**
  * tb_port_clear_counter() - clear a counter in TB_CFG_COUNTER
  *
  * Return: Returns 0 on success or an error code on failure.
  */
 int tb_port_clear_counter(struct tb_port *port, int counter)
 {
 	u32 zero[3] = { 0, 0, 0 };
 	tb_port_info(port, "clearing counter %d\n", counter);
 	return tb_port_write(port, zero, TB_CFG_COUNTERS, 3 * counter, 3);
 }

 /**
  * tb_init_port() - initialize a port
  *
  * This is a helper method for tb_switch_alloc. Does not check or initialize
  * any downstream switches.
  *
  * Return: Returns 0 on success or an error code on failure.
  */
 static int tb_init_port(struct tb_port *port)
 {
 	int res;
 	int cap;

 	res = tb_port_read(port, &port->config, TB_CFG_PORT, 0, 8);
 	if (res)
 		return res;

 	/* Port 0 is the switch itself and has no PHY. */
 	if (port->config.type == TB_TYPE_PORT && port->port != 0) {
 		cap = tb_find_cap(port, TB_CFG_PORT, TB_CAP_PHY);

 		if (cap > 0)
 			port->cap_phy = cap;
 		else
 			tb_port_WARN(port, "non switch port without a PHY\n");
 	}

 	tb_dump_port(port->sw->tb, &port->config);

 	/* TODO: Read dual link port, DP port and more from EEPROM. */
 	return 0;

 }

 /* switch utility functions */

 static void tb_dump_switch(struct tb *tb, struct tb_regs_switch_header *sw)
 {
 	tb_info(tb,
 		" Switch: %x:%x (Revision: %d, TB Version: %d)\n",
 		sw->vendor_id, sw->device_id, sw->revision,
 		sw->thunderbolt_version);
 	tb_info(tb, "  Max Port Number: %d\n", sw->max_port_number);
 	tb_info(tb, "  Config:\n");
 	tb_info(tb,
 		"   Upstream Port Number: %d Depth: %d Route String: %#llx Enabled: %d, PlugEventsDelay: %dms\n",
 		sw->upstream_port_number, sw->depth,
 		(((u64) sw->route_hi) << 32) | sw->route_lo,
 		sw->enabled, sw->plug_events_delay);
 	tb_info(tb,
 		"   unknown1: %#x unknown4: %#x\n",
 		sw->__unknown1, sw->__unknown4);
 }

 /**
  * reset_switch() - reconfigure route, enable and send TB_CFG_PKG_RESET
  *
  * Return: Returns 0 on success or an error code on failure.
  */
 int tb_switch_reset(struct tb *tb, u64 route)
 {
 	struct tb_cfg_result res;
 	struct tb_regs_switch_header header = {
 		header.route_hi = route >> 32,
 		header.route_lo = route,
 		header.enabled = true,
 	};
 	tb_info(tb, "resetting switch at %llx\n", route);
 	res.err = tb_cfg_write(tb->ctl, ((u32 *) &header) + 2, route,
 			0, 2, 2, 2);
 	if (res.err)
 		return res.err;
 	res = tb_cfg_reset(tb->ctl, route, TB_CFG_DEFAULT_TIMEOUT);
 	if (res.err > 0)
 		return -EIO;
 	return res.err;
 }

 struct tb_switch *get_switch_at_route(struct tb_switch *sw, u64 route)
 {
 	u8 next_port = route; /*
 			       * Routes use a stride of 8 bits,
 			       * eventhough a port index has 6 bits at most.
 			       * */
 	if (route == 0)
 		return sw;
 	if (next_port > sw->config.max_port_number)
 		return NULL;
 	if (tb_is_upstream_port(&sw->ports[next_port]))
 		return NULL;
 	if (!sw->ports[next_port].remote)
 		return NULL;
 	return get_switch_at_route(sw->ports[next_port].remote->sw,
 				   route >> TB_ROUTE_SHIFT);
 }

 /**
  * tb_plug_events_active() - enable/disable plug events on a switch
  *
  * Also configures a sane plug_events_delay of 255ms.
  *
  * Return: Returns 0 on success or an error code on failure.
  */
 static int tb_plug_events_active(struct tb_switch *sw, bool active)
 {
 	u32 data;
 	int res;

 	sw->config.plug_events_delay = 0xff;
 	res = tb_sw_write(sw, ((u32 *) &sw->config) + 4, TB_CFG_SWITCH, 4, 1);
 	if (res)
 		return res;

 	res = tb_sw_read(sw, &data, TB_CFG_SWITCH, sw->cap_plug_events + 1, 1);
 	if (res)
 		return res;

 	if (active) {
 		data = data & 0xFFFFFF83;
 		switch (sw->config.device_id) {
 		case PCI_DEVICE_ID_INTEL_LIGHT_RIDGE:
 		case PCI_DEVICE_ID_INTEL_EAGLE_RIDGE:
 		case PCI_DEVICE_ID_INTEL_PORT_RIDGE:
 			break;
 		default:
 			data |= 4;
 		}
 	} else {
 		data = data | 0x7c;
 	}
 	return tb_sw_write(sw, &data, TB_CFG_SWITCH,
 			   sw->cap_plug_events + 1, 1);
 }


 /**
  * tb_switch_free() - free a tb_switch and all downstream switches
  */
 void tb_switch_free(struct tb_switch *sw)
 {
 	int i;
 	/* port 0 is the switch itself and never has a remote */
 	for (i = 1; i <= sw->config.max_port_number; i++) {
 		if (tb_is_upstream_port(&sw->ports[i]))
 			continue;
 		if (sw->ports[i].remote)
 			tb_switch_free(sw->ports[i].remote->sw);
 		sw->ports[i].remote = NULL;
 	}

 	if (!sw->is_unplugged)
 		tb_plug_events_active(sw, false);

 	kfree(sw->ports);
 	kfree(sw->drom);
 	kfree(sw);
 }

 /**
  * tb_switch_alloc() - allocate and initialize a switch
  *
  * Return: Returns a NULL on failure.
  */
 struct tb_switch *tb_switch_alloc(struct tb *tb, u64 route)
 {
 	int i;
 	int cap;
 	struct tb_switch *sw;
 	int upstream_port = tb_cfg_get_upstream_port(tb->ctl, route);
 	if (upstream_port < 0)
 		return NULL;

 	sw = kzalloc(sizeof(*sw), GFP_KERNEL);
 	if (!sw)
 		return NULL;

 	sw->tb = tb;
 	if (tb_cfg_read(tb->ctl, &sw->config, route, 0, TB_CFG_SWITCH, 0, 5))
 		goto err;
 	tb_info(tb,
 		"initializing Switch at %#llx (depth: %d, up port: %d)\n",
 		route, tb_route_length(route), upstream_port);
 	tb_info(tb, "old switch config:\n");
 	tb_dump_switch(tb, &sw->config);

 	/* configure switch */
 	sw->config.upstream_port_number = upstream_port;
 	sw->config.depth = tb_route_length(route);
 	sw->config.route_lo = route;
 	sw->config.route_hi = route >> 32;
 	sw->config.enabled = 1;
 	/* from here on we may use the tb_sw_* functions & macros */

 	if (sw->config.vendor_id != 0x8086)
 		tb_sw_warn(sw, "unknown switch vendor id %#x\n",
 			   sw->config.vendor_id);

 	if (sw->config.device_id != PCI_DEVICE_ID_INTEL_CACTUS_RIDGE_4C &&
 	    sw->config.device_id != PCI_DEVICE_ID_INTEL_PORT_RIDGE)
 		tb_sw_warn(sw, "unsupported switch device id %#x\n",
 			   sw->config.device_id);

 	/* upload configuration */
 	if (tb_sw_write(sw, 1 + (u32 *) &sw->config, TB_CFG_SWITCH, 1, 3))
 		goto err;

 	/* initialize ports */
 	sw->ports = kcalloc(sw->config.max_port_number + 1, sizeof(*sw->ports),
 				GFP_KERNEL);
 	if (!sw->ports)
 		goto err;

 	for (i = 0; i <= sw->config.max_port_number; i++) {
 		/* minimum setup for tb_find_cap and tb_drom_read to work */
 		sw->ports[i].sw = sw;
 		sw->ports[i].port = i;
 	}

 	cap = tb_find_cap(&sw->ports[0], TB_CFG_SWITCH, TB_CAP_PLUG_EVENTS);
 	if (cap < 0) {
 		tb_sw_warn(sw, "cannot find TB_CAP_PLUG_EVENTS aborting\n");
 		goto err;
 	}
 	sw->cap_plug_events = cap;

 	/* read drom */
 	if (tb_drom_read(sw))
 		tb_sw_warn(sw, "tb_eeprom_read_rom failed, continuing\n");
 	tb_sw_info(sw, "uid: %#llx\n", sw->uid);

 	for (i = 0; i <= sw->config.max_port_number; i++) {
 		if (sw->ports[i].disabled) {
 			tb_port_info(&sw->ports[i], "disabled by eeprom\n");
 			continue;
 		}
 		if (tb_init_port(&sw->ports[i]))
 			goto err;
 	}

 	/* TODO: I2C, IECS, link controller */

 	if (tb_plug_events_active(sw, true))
 		goto err;

 	return sw;
 err:
 	kfree(sw->ports);
 	kfree(sw->drom);
 	kfree(sw);
 	return NULL;
 }

 /**
  * tb_sw_set_unplugged() - set is_unplugged on switch and downstream switches
  */
 void tb_sw_set_unplugged(struct tb_switch *sw)
 {
 	int i;
 	if (sw == sw->tb->root_switch) {
 		tb_sw_WARN(sw, "cannot unplug root switch\n");
 		return;
 	}
 	if (sw->is_unplugged) {
 		tb_sw_WARN(sw, "is_unplugged already set\n");
 		return;
 	}
 	sw->is_unplugged = true;
 	for (i = 0; i <= sw->config.max_port_number; i++) {
 		if (!tb_is_upstream_port(&sw->ports[i]) && sw->ports[i].remote)
 			tb_sw_set_unplugged(sw->ports[i].remote->sw);
 	}
 }

 int tb_switch_resume(struct tb_switch *sw)
 {
 	int i, err;
 	u64 uid;
 	tb_sw_info(sw, "resuming switch\n");

 	err = tb_drom_read_uid_only(sw, &uid);
 	if (err) {
 		tb_sw_warn(sw, "uid read failed\n");
 		return err;
 	}
 	if (sw->uid != uid) {
 		tb_sw_info(sw,
 			"changed while suspended (uid %#llx -> %#llx)\n",
 			sw->uid, uid);
 		return -ENODEV;
 	}

 	/* upload configuration */
 	err = tb_sw_write(sw, 1 + (u32 *) &sw->config, TB_CFG_SWITCH, 1, 3);
 	if (err)
 		return err;

 	err = tb_plug_events_active(sw, true);
 	if (err)
 		return err;

 	/* check for surviving downstream switches */
 	for (i = 1; i <= sw->config.max_port_number; i++) {
 		struct tb_port *port = &sw->ports[i];
 		if (tb_is_upstream_port(port))
 			continue;
 		if (!port->remote)
 			continue;
 		if (tb_wait_for_port(port, true) <= 0
 			|| tb_switch_resume(port->remote->sw)) {
 			tb_port_warn(port,
 				     "lost during suspend, disconnecting\n");
 			tb_sw_set_unplugged(port->remote->sw);
 		}
 	}
 	return 0;
 }

 void tb_switch_suspend(struct tb_switch *sw)
 {
 	int i, err;
 	err = tb_plug_events_active(sw, false);
 	if (err)
 		return;

 	for (i = 1; i <= sw->config.max_port_number; i++) {
 		if (!tb_is_upstream_port(&sw->ports[i]) && sw->ports[i].remote)
 			tb_switch_suspend(sw->ports[i].remote->sw);
 	}
 	/*
 	 * TODO: invoke tb_cfg_prepare_to_sleep here? does not seem to have any
 	 * effect?
 	 */
 }
	/*
	* Thunderbolt Cactus Ridge driver - switch/port utility functions
	*
	* Copyright (c) 2014 Andreas Noever <andreas.noever@gmail.com>
	*/

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

	#include "tb.h"

	/* port utility functions */

	static const char tb_port_type(struct tb_regs_port_header port)
	{
	switch (port->type >> 16) {
	case 0:
	switch ((u8) port->type) {
	case 0:
	return "Inactive";
	case 1:
	return "Port";
	case 2:
	return "NHI";
	default:
	return "unknown";
	}
	case 0x2:
	return "Ethernet";
	case 0x8:
	return "SATA";
	case 0xe:
	return "DP/HDMI";
	case 0x10:
	return "PCIe";
	case 0x20:
	return "USB";
	default:
	return "unknown";
	}
	}

	static void tb_dump_port(struct tb tb, struct tb_regs_port_header port)
	{
	tb_info(tb,
	" Port %d: %x:%x (Revision: %d, TB Version: %d, Type: %s (%#x))\n",
	port->port_number, port->vendor_id, port->device_id,
	port->revision, port->thunderbolt_version, tb_port_type(port),
	port->type);
	tb_info(tb, " Max hop id (in/out): %d/%d\n",
	port->max_in_hop_id, port->max_out_hop_id);
	tb_info(tb, " Max counters: %d\n", port->max_counters);
	tb_info(tb, " NFC Credits: %#x\n", port->nfc_credits);
	}

	/**
	* tb_port_state() - get connectedness state of a port
	*
	* The port must have a TB_CAP_PHY (i.e. it should be a real port).
	*
	* Return: Returns an enum tb_port_state on success or an error code on failure.
	*/
	static int tb_port_state(struct tb_port *port)
	{
	struct tb_cap_phy phy;
	int res;
	if (port->cap_phy == 0) {
	tb_port_WARN(port, "does not have a PHY\n");
	return -EINVAL;
	}
	res = tb_port_read(port, &phy, TB_CFG_PORT, port->cap_phy, 2);
	if (res)
	return res;
	return phy.state;
	}

	/**
	* tb_wait_for_port() - wait for a port to become ready
	*
	* Wait up to 1 second for a port to reach state TB_PORT_UP. If
	* wait_if_unplugged is set then we also wait if the port is in state
	* TB_PORT_UNPLUGGED (it takes a while for the device to be registered after
	* switch resume). Otherwise we only wait if a device is registered but the link
	* has not yet been established.
	*
	* Return: Returns an error code on failure. Returns 0 if the port is not
	* connected or failed to reach state TB_PORT_UP within one second. Returns 1
	* if the port is connected and in state TB_PORT_UP.
	*/
	int tb_wait_for_port(struct tb_port *port, bool wait_if_unplugged)
	{
	int retries = 10;
	int state;
	if (!port->cap_phy) {
	tb_port_WARN(port, "does not have PHY\n");
	return -EINVAL;
	}
	if (tb_is_upstream_port(port)) {
	tb_port_WARN(port, "is the upstream port\n");
	return -EINVAL;
	}

	while (retries--) {
	state = tb_port_state(port);
	if (state < 0)
	return state;
	if (state == TB_PORT_DISABLED) {
	tb_port_info(port, "is disabled (state: 0)\n");
	return 0;
	}
	if (state == TB_PORT_UNPLUGGED) {
	if (wait_if_unplugged) {
	/* used during resume */
	tb_port_info(port,
	"is unplugged (state: 7), retrying...\n");
	msleep(100);
	continue;
	}
	tb_port_info(port, "is unplugged (state: 7)\n");
	return 0;
	}
	if (state == TB_PORT_UP) {
	tb_port_info(port,
	"is connected, link is up (state: 2)\n");
	return 1;
	}

	/*
	* After plug-in the state is TB_PORT_CONNECTING. Give it some
	* time.
	*/
	tb_port_info(port,
	"is connected, link is not up (state: %d), retrying...\n",
	state);
	msleep(100);
	}
	tb_port_warn(port,
	"failed to reach state TB_PORT_UP. Ignoring port...\n");
	return 0;
	}

	/**
	* tb_port_add_nfc_credits() - add/remove non flow controlled credits to port
	*
	* Change the number of NFC credits allocated to @port by @credits. To remove
	* NFC credits pass a negative amount of credits.
	*
	* Return: Returns 0 on success or an error code on failure.
	*/
	int tb_port_add_nfc_credits(struct tb_port *port, int credits)
	{
	if (credits == 0)
	return 0;
	tb_port_info(port,
	"adding %#x NFC credits (%#x -> %#x)",
	credits,
	port->config.nfc_credits,
	port->config.nfc_credits + credits);
	port->config.nfc_credits += credits;
	return tb_port_write(port, &port->config.nfc_credits,
	TB_CFG_PORT, 4, 1);
	}

	/**
	* tb_port_clear_counter() - clear a counter in TB_CFG_COUNTER
	*
	* Return: Returns 0 on success or an error code on failure.
	*/
	int tb_port_clear_counter(struct tb_port *port, int counter)
	{
	u32 zero[3] = { 0, 0, 0 };
	tb_port_info(port, "clearing counter %d\n", counter);
	return tb_port_write(port, zero, TB_CFG_COUNTERS, 3 * counter, 3);
	}

	/**
	* tb_init_port() - initialize a port
	*
	* This is a helper method for tb_switch_alloc. Does not check or initialize
	* any downstream switches.
	*
	* Return: Returns 0 on success or an error code on failure.
	*/
	static int tb_init_port(struct tb_port *port)
	{
	int res;
	int cap;

	res = tb_port_read(port, &port->config, TB_CFG_PORT, 0, 8);
	if (res)
	return res;

	/* Port 0 is the switch itself and has no PHY. */
	if (port->config.type == TB_TYPE_PORT && port->port != 0) {
	cap = tb_find_cap(port, TB_CFG_PORT, TB_CAP_PHY);

	if (cap > 0)
	port->cap_phy = cap;
	else
	tb_port_WARN(port, "non switch port without a PHY\n");
	}

	tb_dump_port(port->sw->tb, &port->config);

	/* TODO: Read dual link port, DP port and more from EEPROM. */
	return 0;

	}

	/* switch utility functions */

	static void tb_dump_switch(struct tb tb, struct tb_regs_switch_header sw)
	{
	tb_info(tb,
	" Switch: %x:%x (Revision: %d, TB Version: %d)\n",
	sw->vendor_id, sw->device_id, sw->revision,
	sw->thunderbolt_version);
	tb_info(tb, " Max Port Number: %d\n", sw->max_port_number);
	tb_info(tb, " Config:\n");
	tb_info(tb,
	" Upstream Port Number: %d Depth: %d Route String: %#llx Enabled: %d, PlugEventsDelay: %dms\n",
	sw->upstream_port_number, sw->depth,
	(((u64) sw->route_hi) << 32) \| sw->route_lo,
	sw->enabled, sw->plug_events_delay);
	tb_info(tb,
	" unknown1: %#x unknown4: %#x\n",
	sw->__unknown1, sw->__unknown4);
	}

	/**
	* reset_switch() - reconfigure route, enable and send TB_CFG_PKG_RESET
	*
	* Return: Returns 0 on success or an error code on failure.
	*/
	int tb_switch_reset(struct tb *tb, u64 route)
	{
	struct tb_cfg_result res;
	struct tb_regs_switch_header header = {
	header.route_hi = route >> 32,
	header.route_lo = route,
	header.enabled = true,
	};
	tb_info(tb, "resetting switch at %llx\n", route);
	res.err = tb_cfg_write(tb->ctl, ((u32 *) &header) + 2, route,
	0, 2, 2, 2);
	if (res.err)
	return res.err;
	res = tb_cfg_reset(tb->ctl, route, TB_CFG_DEFAULT_TIMEOUT);
	if (res.err > 0)
	return -EIO;
	return res.err;
	}

	struct tb_switch get_switch_at_route(struct tb_switch sw, u64 route)
	{
	u8 next_port = route; /*
	* Routes use a stride of 8 bits,
	* eventhough a port index has 6 bits at most.
	* */
	if (route == 0)
	return sw;
	if (next_port > sw->config.max_port_number)
	return NULL;
	if (tb_is_upstream_port(&sw->ports[next_port]))
	return NULL;
	if (!sw->ports[next_port].remote)
	return NULL;
	return get_switch_at_route(sw->ports[next_port].remote->sw,
	route >> TB_ROUTE_SHIFT);
	}

	/**
	* tb_plug_events_active() - enable/disable plug events on a switch
	*
	* Also configures a sane plug_events_delay of 255ms.
	*
	* Return: Returns 0 on success or an error code on failure.
	*/
	static int tb_plug_events_active(struct tb_switch *sw, bool active)
	{
	u32 data;
	int res;

	sw->config.plug_events_delay = 0xff;
	res = tb_sw_write(sw, ((u32 *) &sw->config) + 4, TB_CFG_SWITCH, 4, 1);
	if (res)
	return res;

	res = tb_sw_read(sw, &data, TB_CFG_SWITCH, sw->cap_plug_events + 1, 1);
	if (res)
	return res;

	if (active) {
	data = data & 0xFFFFFF83;
	switch (sw->config.device_id) {
	case PCI_DEVICE_ID_INTEL_LIGHT_RIDGE:
	case PCI_DEVICE_ID_INTEL_EAGLE_RIDGE:
	case PCI_DEVICE_ID_INTEL_PORT_RIDGE:
	break;
	default:
	data \|= 4;
	}
	} else {
	data = data \| 0x7c;
	}
	return tb_sw_write(sw, &data, TB_CFG_SWITCH,
	sw->cap_plug_events + 1, 1);
	}


	/**
	* tb_switch_free() - free a tb_switch and all downstream switches
	*/
	void tb_switch_free(struct tb_switch *sw)
	{
	int i;
	/* port 0 is the switch itself and never has a remote */
	for (i = 1; i <= sw->config.max_port_number; i++) {
	if (tb_is_upstream_port(&sw->ports[i]))
	continue;
	if (sw->ports[i].remote)
	tb_switch_free(sw->ports[i].remote->sw);
	sw->ports[i].remote = NULL;
	}

	if (!sw->is_unplugged)
	tb_plug_events_active(sw, false);

	kfree(sw->ports);
	kfree(sw->drom);
	kfree(sw);
	}

	/**
	* tb_switch_alloc() - allocate and initialize a switch
	*
	* Return: Returns a NULL on failure.
	*/
	struct tb_switch tb_switch_alloc(struct tb tb, u64 route)
	{
	int i;
	int cap;
	struct tb_switch *sw;
	int upstream_port = tb_cfg_get_upstream_port(tb->ctl, route);
	if (upstream_port < 0)
	return NULL;

	sw = kzalloc(sizeof(*sw), GFP_KERNEL);
	if (!sw)
	return NULL;

	sw->tb = tb;
	if (tb_cfg_read(tb->ctl, &sw->config, route, 0, TB_CFG_SWITCH, 0, 5))
	goto err;
	tb_info(tb,
	"initializing Switch at %#llx (depth: %d, up port: %d)\n",
	route, tb_route_length(route), upstream_port);
	tb_info(tb, "old switch config:\n");
	tb_dump_switch(tb, &sw->config);

	/* configure switch */
	sw->config.upstream_port_number = upstream_port;
	sw->config.depth = tb_route_length(route);
	sw->config.route_lo = route;
	sw->config.route_hi = route >> 32;
	sw->config.enabled = 1;
	/* from here on we may use the tb_sw_* functions & macros */

	if (sw->config.vendor_id != 0x8086)
	tb_sw_warn(sw, "unknown switch vendor id %#x\n",
	sw->config.vendor_id);

	if (sw->config.device_id != PCI_DEVICE_ID_INTEL_CACTUS_RIDGE_4C &&
	sw->config.device_id != PCI_DEVICE_ID_INTEL_PORT_RIDGE)
	tb_sw_warn(sw, "unsupported switch device id %#x\n",
	sw->config.device_id);

	/* upload configuration */
	if (tb_sw_write(sw, 1 + (u32 *) &sw->config, TB_CFG_SWITCH, 1, 3))
	goto err;

	/* initialize ports */
	sw->ports = kcalloc(sw->config.max_port_number + 1, sizeof(*sw->ports),
	GFP_KERNEL);
	if (!sw->ports)
	goto err;

	for (i = 0; i <= sw->config.max_port_number; i++) {
	/* minimum setup for tb_find_cap and tb_drom_read to work */
	sw->ports[i].sw = sw;
	sw->ports[i].port = i;
	}

	cap = tb_find_cap(&sw->ports[0], TB_CFG_SWITCH, TB_CAP_PLUG_EVENTS);
	if (cap < 0) {
	tb_sw_warn(sw, "cannot find TB_CAP_PLUG_EVENTS aborting\n");
	goto err;
	}
	sw->cap_plug_events = cap;

	/* read drom */
	if (tb_drom_read(sw))
	tb_sw_warn(sw, "tb_eeprom_read_rom failed, continuing\n");
	tb_sw_info(sw, "uid: %#llx\n", sw->uid);

	for (i = 0; i <= sw->config.max_port_number; i++) {
	if (sw->ports[i].disabled) {
	tb_port_info(&sw->ports[i], "disabled by eeprom\n");
	continue;
	}
	if (tb_init_port(&sw->ports[i]))
	goto err;
	}

	/* TODO: I2C, IECS, link controller */

	if (tb_plug_events_active(sw, true))
	goto err;

	return sw;
	err:
	kfree(sw->ports);
	kfree(sw->drom);
	kfree(sw);
	return NULL;
	}

	/**
	* tb_sw_set_unplugged() - set is_unplugged on switch and downstream switches
	*/
	void tb_sw_set_unplugged(struct tb_switch *sw)
	{
	int i;
	if (sw == sw->tb->root_switch) {
	tb_sw_WARN(sw, "cannot unplug root switch\n");
	return;
	}
	if (sw->is_unplugged) {
	tb_sw_WARN(sw, "is_unplugged already set\n");
	return;
	}
	sw->is_unplugged = true;
	for (i = 0; i <= sw->config.max_port_number; i++) {
	if (!tb_is_upstream_port(&sw->ports[i]) && sw->ports[i].remote)
	tb_sw_set_unplugged(sw->ports[i].remote->sw);
	}
	}

	int tb_switch_resume(struct tb_switch *sw)
	{
	int i, err;
	u64 uid;
	tb_sw_info(sw, "resuming switch\n");

	err = tb_drom_read_uid_only(sw, &uid);
	if (err) {
	tb_sw_warn(sw, "uid read failed\n");
	return err;
	}
	if (sw->uid != uid) {
	tb_sw_info(sw,
	"changed while suspended (uid %#llx -> %#llx)\n",
	sw->uid, uid);
	return -ENODEV;
	}

	/* upload configuration */
	err = tb_sw_write(sw, 1 + (u32 *) &sw->config, TB_CFG_SWITCH, 1, 3);
	if (err)
	return err;

	err = tb_plug_events_active(sw, true);
	if (err)
	return err;

	/* check for surviving downstream switches */
	for (i = 1; i <= sw->config.max_port_number; i++) {
	struct tb_port *port = &sw->ports[i];
	if (tb_is_upstream_port(port))
	continue;
	if (!port->remote)
	continue;
	if (tb_wait_for_port(port, true) <= 0
	\|\| tb_switch_resume(port->remote->sw)) {
	tb_port_warn(port,
	"lost during suspend, disconnecting\n");
	tb_sw_set_unplugged(port->remote->sw);
	}
	}
	return 0;
	}

	void tb_switch_suspend(struct tb_switch *sw)
	{
	int i, err;
	err = tb_plug_events_active(sw, false);
	if (err)
	return;

	for (i = 1; i <= sw->config.max_port_number; i++) {
	if (!tb_is_upstream_port(&sw->ports[i]) && sw->ports[i].remote)
	tb_switch_suspend(sw->ports[i].remote->sw);
	}
	/*
	* TODO: invoke tb_cfg_prepare_to_sleep here? does not seem to have any
	* effect?
	*/
	}