text: // SPDX-License-Identifier: GPL-2.0
  /*
   * Thunderbolt driver - switch/port utility functions
   *
   * Copyright (c) 2014 Andreas Noever <andreas.noever@gmail.com>
   * Copyright (C) 2018, Intel Corporation
   */
  
  #include <linux/delay.h>
  #include <linux/idr.h>
  #include <linux/nvmem-provider.h>
  #include <linux/pm_runtime.h>
  #include <linux/sizes.h>
  #include <linux/slab.h>
  #include <linux/vmalloc.h>
  
  #include "tb.h"
  
  /* Switch authorization from userspace is serialized by this lock */
  static DEFINE_MUTEX(switch_lock);
  
  /* Switch NVM support */
  
  #define NVM_DEVID		0x05
  #define NVM_VERSION		0x08
  #define NVM_CSS			0x10
  #define NVM_FLASH_SIZE		0x45
  
  #define NVM_MIN_SIZE		SZ_32K
  #define NVM_MAX_SIZE		SZ_512K
  
  static DEFINE_IDA(nvm_ida);
  
  struct nvm_auth_status {
  	struct list_head list;
  	uuid_t uuid;
  	u32 status;
  };
  
  /*
   * Hold NVM authentication failure status per switch This information
   * needs to stay around even when the switch gets power cycled so we
   * keep it separately.
   */
  static LIST_HEAD(nvm_auth_status_cache);
  static DEFINE_MUTEX(nvm_auth_status_lock);
  
  static struct nvm_auth_status *__nvm_get_auth_status(const struct tb_switch *sw)
  {
  	struct nvm_auth_status *st;
  
  	list_for_each_entry(st, &nvm_auth_status_cache, list) {
  		if (uuid_equal(&st->uuid, sw->uuid))
  			return st;
  	}
  
  	return NULL;
  }
  
  static void nvm_get_auth_status(const struct tb_switch *sw, u32 *status)
  {
  	struct nvm_auth_status *st;
  
  	mutex_lock(&nvm_auth_status_lock);
  	st = __nvm_get_auth_status(sw);
  	mutex_unlock(&nvm_auth_status_lock);
  
  	*status = st ? st->status : 0;
  }
  
  static void nvm_set_auth_status(const struct tb_switch *sw, u32 status)
  {
  	struct nvm_auth_status *st;
  
  	if (WARN_ON(!sw->uuid))
  		return;
  
  	mutex_lock(&nvm_auth_status_lock);
  	st = __nvm_get_auth_status(sw);
  
  	if (!st) {
  		st = kzalloc(sizeof(*st), GFP_KERNEL);
  		if (!st)
  			goto unlock;
  
  		memcpy(&st->uuid, sw->uuid, sizeof(st->uuid));
  		INIT_LIST_HEAD(&st->list);
  		list_add_tail(&st->list, &nvm_auth_status_cache);
  	}
  
  	st->status = status;
  unlock:
  	mutex_unlock(&nvm_auth_status_lock);
  }
  
  static void nvm_clear_auth_status(const struct tb_switch *sw)
  {
  	struct nvm_auth_status *st;
  
  	mutex_lock(&nvm_auth_status_lock);
  	st = __nvm_get_auth_status(sw);
  	if (st) {
  		list_del(&st->list);
  		kfree(st);
  	}
  	mutex_unlock(&nvm_auth_status_lock);
  }
  
  static int nvm_validate_and_write(struct tb_switch *sw)
  {
  	unsigned int image_size, hdr_size;
  	const u8 *buf = sw->nvm->buf;
  	u16 ds_size;
  	int ret;
  
  	if (!buf)
  		return -EINVAL;
  
  	image_size = sw->nvm->buf_data_size;
  	if (image_size < NVM_MIN_SIZE || image_size > NVM_MAX_SIZE)
  		return -EINVAL;
  
  	/*
  	 * FARB pointer must point inside the image and must at least
  	 * contain parts of the digital section we will be reading here.
  	 */
  	hdr_size = (*(u32 *)buf) & 0xffffff;
  	if (hdr_size + NVM_DEVID + 2 >= image_size)
  		return -EINVAL;
  
  	/* Digital section start should be aligned to 4k page */
  	if (!IS_ALIGNED(hdr_size, SZ_4K))
  		return -EINVAL;
  
  	/*
  	 * Read digital section size and check that it also fits inside
  	 * the image.
  	 */
  	ds_size = *(u16 *)(buf + hdr_size);
  	if (ds_size >= image_size)
  		return -EINVAL;
  
  	if (!sw->safe_mode) {
  		u16 device_id;
  
  		/*
  		 * Make sure the device ID in the image matches the one
  		 * we read from the switch config space.
  		 */
  		device_id = *(u16 *)(buf + hdr_size + NVM_DEVID);
  		if (device_id != sw->config.device_id)
  			return -EINVAL;
  
  		if (sw->generation < 3) {
  			/* Write CSS headers first */
  			ret = dma_port_flash_write(sw->dma_port,
  				DMA_PORT_CSS_ADDRESS, buf + NVM_CSS,
  				DMA_PORT_CSS_MAX_SIZE);
  			if (ret)
  				return ret;
  		}
  
  		/* Skip headers in the image */
  		buf += hdr_size;
  		image_size -= hdr_size;
  	}
  
  	return dma_port_flash_write(sw->dma_port, 0, buf, image_size);
  }
  
  static int nvm_authenticate_host(struct tb_switch *sw)
  {
  	int ret;
  
  	/*
  	 * Root switch NVM upgrade requires that we disconnect the
  	 * existing paths first (in case it is not in safe mode
  	 * already).
  	 */
  	if (!sw->safe_mode) {
  		ret = tb_domain_disconnect_all_paths(sw->tb);
  		if (ret)
  			return ret;
  		/*
  		 * The host controller goes away pretty soon after this if
  		 * everything goes well so getting timeout is expected.
  		 */
  		ret = dma_port_flash_update_auth(sw->dma_port);
  		return ret == -ETIMEDOUT ? 0 : ret;
  	}
  
  	/*
  	 * From safe mode we can get out by just power cycling the
  	 * switch.
  	 */
  	dma_port_power_cycle(sw->dma_port);
  	return 0;
  }
  
  static int nvm_authenticate_device(struct tb_switch *sw)
  {
  	int ret, retries = 10;
  
  	ret = dma_port_flash_update_auth(sw->dma_port);
  	if (ret && ret != -ETIMEDOUT)
  		return ret;
  
  	/*
  	 * Poll here for the authentication status. It takes some time
  	 * for the device to respond (we get timeout for a while). Once
  	 * we get response the device needs to be power cycled in order
  	 * to the new NVM to be taken into use.
  	 */
  	do {
  		u32 status;
  
  		ret = dma_port_flash_update_auth_status(sw->dma_port, &status);
  		if (ret < 0 && ret != -ETIMEDOUT)
  			return ret;
  		if (ret > 0) {
  			if (status) {
  				tb_sw_warn(sw, "failed to authenticate NVM\n");
  				nvm_set_auth_status(sw, status);
  			}
  
  			tb_sw_info(sw, "power cycling the switch now\n");
  			dma_port_power_cycle(sw->dma_port);
  			return 0;
  		}
  
  		msleep(500);
  	} while (--retries);
  
  	return -ETIMEDOUT;
  }
  
  static int tb_switch_nvm_read(void *priv, unsigned int offset, void *val,
  			      size_t bytes)
  {
  	struct tb_switch *sw = priv;
  	int ret;
  
  	pm_runtime_get_sync(&sw->dev);
  	ret = dma_port_flash_read(sw->dma_port, offset, val, bytes);
  	pm_runtime_mark_last_busy(&sw->dev);
  	pm_runtime_put_autosuspend(&sw->dev);
  
  	return ret;
  }
  
  static int tb_switch_nvm_write(void *priv, unsigned int offset, void *val,
  			       size_t bytes)
  {
  	struct tb_switch *sw = priv;
  	int ret = 0;
  
  	if (mutex_lock_interruptible(&switch_lock))
  		return -ERESTARTSYS;
  
  	/*
  	 * Since writing the NVM image might require some special steps,
  	 * for example when CSS headers are written, we cache the image
  	 * locally here and handle the special cases when the user asks
  	 * us to authenticate the image.
  	 */
  	if (!sw->nvm->buf) {
  		sw->nvm->buf = vmalloc(NVM_MAX_SIZE);
  		if (!sw->nvm->buf) {
  			ret = -ENOMEM;
  			goto unlock;
  		}
  	}
  
  	sw->nvm->buf_data_size = offset + bytes;
  	memcpy(sw->nvm->buf + offset, val, bytes);
  
  unlock:
  	mutex_unlock(&switch_lock);
  
  	return ret;
  }
  
  static struct nvmem_device *register_nvmem(struct tb_switch *sw, int id,
  					   size_t size, bool active)
  {
  	struct nvmem_config config;
  
  	memset(&config, 0, sizeof(config));
  
  	if (active) {
  		config.name = "nvm_active";
  		config.reg_read = tb_switch_nvm_read;
  		config.read_only = true;
  	} else {
  		config.name = "nvm_non_active";
  		config.reg_write = tb_switch_nvm_write;
  		config.root_only = true;
  	}
  
  	config.id = id;
  	config.stride = 4;
  	config.word_size = 4;
  	config.size = size;
  	config.dev = &sw->dev;
  	config.owner = THIS_MODULE;
  	config.priv = sw;
  
  	return nvmem_register(&config);
  }
  
  static int tb_switch_nvm_add(struct tb_switch *sw)
  {
  	struct nvmem_device *nvm_dev;
  	struct tb_switch_nvm *nvm;
  	u32 val;
  	int ret;
  
  	if (!sw->dma_port)
  		return 0;
  
  	nvm = kzalloc(sizeof(*nvm), GFP_KERNEL);
  	if (!nvm)
  		return -ENOMEM;
  
  	nvm->id = ida_simple_get(&nvm_ida, 0, 0, GFP_KERNEL);
  
  	/*
  	 * If the switch is in safe-mode the only accessible portion of
  	 * the NVM is the non-active one where userspace is expected to
  	 * write new functional NVM.
  	 */
  	if (!sw->safe_mode) {
  		u32 nvm_size, hdr_size;
  
  		ret = dma_port_flash_read(sw->dma_port, NVM_FLASH_SIZE, &val,
  					  sizeof(val));
  		if (ret)
  			goto err_ida;
  
  		hdr_size = sw->generation < 3 ? SZ_8K : SZ_16K;
  		nvm_size = (SZ_1M << (val & 7)) / 8;
  		nvm_size = (nvm_size - hdr_size) / 2;
  
  		ret = dma_port_flash_read(sw->dma_port, NVM_VERSION, &val,
  					  sizeof(val));
  		if (ret)
  			goto err_ida;
  
  		nvm->major = val >> 16;
  		nvm->minor = val >> 8;
  
  		nvm_dev = register_nvmem(sw, nvm->id, nvm_size, true);
  		if (IS_ERR(nvm_dev)) {
  			ret = PTR_ERR(nvm_dev);
  			goto err_ida;
  		}
  		nvm->active = nvm_dev;
  	}
  
  	nvm_dev = register_nvmem(sw, nvm->id, NVM_MAX_SIZE, false);
  	if (IS_ERR(nvm_dev)) {
  		ret = PTR_ERR(nvm_dev);
  		goto err_nvm_active;
  	}
  	nvm->non_active = nvm_dev;
  
  	mutex_lock(&switch_lock);
  	sw->nvm = nvm;
  	mutex_unlock(&switch_lock);
  
  	return 0;
  
  err_nvm_active:
  	if (nvm->active)
  		nvmem_unregister(nvm->active);
  err_ida:
  	ida_simple_remove(&nvm_ida, nvm->id);
  	kfree(nvm);
  
  	return ret;
  }
  
  static void tb_switch_nvm_remove(struct tb_switch *sw)
  {
  	struct tb_switch_nvm *nvm;
  
  	mutex_lock(&switch_lock);
  	nvm = sw->nvm;
  	sw->nvm = NULL;
  	mutex_unlock(&switch_lock);
  
  	if (!nvm)
  		return;
  
  	/* Remove authentication status in case the switch is unplugged */
  	if (!nvm->authenticating)
  		nvm_clear_auth_status(sw);
  
  	nvmem_unregister(nvm->non_active);
  	if (nvm->active)
  		nvmem_unregister(nvm->active);
  	ida_simple_remove(&nvm_ida, nvm->id);
  	vfree(nvm->buf);
  	kfree(nvm);
  }
  
  /* 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_dbg(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_dbg(tb, "  Max hop id (in/out): %d/%d\n",
  	       port->max_in_hop_id, port->max_out_hop_id);
  	tb_dbg(tb, "  Max counters: %d\n", port->max_counters);
  	tb_dbg(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_port_find_cap(port, TB_PORT_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_dbg(tb, " Switch: %x:%x (Revision: %d, TB Version: %d)\n",
  	       sw->vendor_id, sw->device_id, sw->revision,
  	       sw->thunderbolt_version);
  	tb_dbg(tb, "  Max Port Number: %d\n", sw->max_port_number);
  	tb_dbg(tb, "  Config:\n");
  	tb_dbg(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_dbg(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_dbg(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;
  
  	if (!sw->config.enabled)
  		return 0;
  
  	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);
  }
  
  static ssize_t authorized_show(struct device *dev,
  			       struct device_attribute *attr,
  			       char *buf)
  {
  	struct tb_switch *sw = tb_to_switch(dev);
  
  	return sprintf(buf, "%u\n", sw->authorized);
  }
  
  static int tb_switch_set_authorized(struct tb_switch *sw, unsigned int val)
  {
  	int ret = -EINVAL;
  
  	if (mutex_lock_interruptible(&switch_lock))
  		return -ERESTARTSYS;
  
  	if (sw->authorized)
  		goto unlock;
  
  	/*
  	 * Make sure there is no PCIe rescan ongoing when a new PCIe
  	 * tunnel is created. Otherwise the PCIe rescan code might find
  	 * the new tunnel too early.
  	 */
  	pci_lock_rescan_remove();
  	pm_runtime_get_sync(&sw->dev);
  
  	switch (val) {
  	/* Approve switch */
  	case 1:
  		if (sw->key)
  			ret = tb_domain_approve_switch_key(sw->tb, sw);
  		else
  			ret = tb_domain_approve_switch(sw->tb, sw);
  		break;
  
  	/* Challenge switch */
  	case 2:
  		if (sw->key)
  			ret = tb_domain_challenge_switch_key(sw->tb, sw);
  		break;
  
  	default:
  		break;
  	}
  
  	pm_runtime_mark_last_busy(&sw->dev);
  	pm_runtime_put_autosuspend(&sw->dev);
  	pci_unlock_rescan_remove();
  
  	if (!ret) {
  		sw->authorized = val;
  		/* Notify status change to the userspace */
  		kobject_uevent(&sw->dev.kobj, KOBJ_CHANGE);
  	}
  
  unlock:
  	mutex_unlock(&switch_lock);
  	return ret;
  }
  
  static ssize_t authorized_store(struct device *dev,
  				struct device_attribute *attr,
  				const char *buf, size_t count)
  {
  	struct tb_switch *sw = tb_to_switch(dev);
  	unsigned int val;
  	ssize_t ret;
  
  	ret = kstrtouint(buf, 0, &val);
  	if (ret)
  		return ret;
  	if (val > 2)
  		return -EINVAL;
  
  	ret = tb_switch_set_authorized(sw, val);
  
  	return ret ? ret : count;
  }
  static DEVICE_ATTR_RW(authorized);
  
  static ssize_t boot_show(struct device *dev, struct device_attribute *attr,
  			 char *buf)
  {
  	struct tb_switch *sw = tb_to_switch(dev);
  
  	return sprintf(buf, "%u\n", sw->boot);
  }
  static DEVICE_ATTR_RO(boot);
  
  static ssize_t device_show(struct device *dev, struct device_attribute *attr,
  			   char *buf)
  {
  	struct tb_switch *sw = tb_to_switch(dev);
  
  	return sprintf(buf, "%#x\n", sw->device);
  }
  static DEVICE_ATTR_RO(device);
  
  static ssize_t
  device_name_show(struct device *dev, struct device_attribute *attr, char *buf)
  {
  	struct tb_switch *sw = tb_to_switch(dev);
  
  	return sprintf(buf, "%s\n", sw->device_name ? sw->device_name : "");
  }
  static DEVICE_ATTR_RO(device_name);
  
  static ssize_t key_show(struct device *dev, struct device_attribute *attr,
  			char *buf)
  {
  	struct tb_switch *sw = tb_to_switch(dev);
  	ssize_t ret;
  
  	if (mutex_lock_interruptible(&switch_lock))
  		return -ERESTARTSYS;
  
  	if (sw->key)
  		ret = sprintf(buf, "%*phN\n", TB_SWITCH_KEY_SIZE, sw->key);
  	else
  		ret = sprintf(buf, "\n");
  
  	mutex_unlock(&switch_lock);
  	return ret;
  }
  
  static ssize_t key_store(struct device *dev, struct device_attribute *attr,
  			 const char *buf, size_t count)
  {
  	struct tb_switch *sw = tb_to_switch(dev);
  	u8 key[TB_SWITCH_KEY_SIZE];
  	ssize_t ret = count;
  	bool clear = false;
  
  	if (!strcmp(buf, "\n"))
  		clear = true;
  	else if (hex2bin(key, buf, sizeof(key)))
  		return -EINVAL;
  
  	if (mutex_lock_interruptible(&switch_lock))
  		return -ERESTARTSYS;
  
  	if (sw->authorized) {
  		ret = -EBUSY;
  	} else {
  		kfree(sw->key);
  		if (clear) {
  			sw->key = NULL;
  		} else {
  			sw->key = kmemdup(key, sizeof(key), GFP_KERNEL);
  			if (!sw->key)
  				ret = -ENOMEM;
  		}
  	}
  
  	mutex_unlock(&switch_lock);
  	return ret;
  }
  static DEVICE_ATTR(key, 0600, key_show, key_store);
  
  static void nvm_authenticate_start(struct tb_switch *sw)
  {
  	struct pci_dev *root_port;
  
  	/*
  	 * During host router NVM upgrade we should not allow root port to
  	 * go into D3cold because some root ports cannot trigger PME
  	 * itself. To be on the safe side keep the root port in D0 during
  	 * the whole upgrade process.
  	 */
  	root_port = pci_find_pcie_root_port(sw->tb->nhi->pdev);
  	if (root_port)
  		pm_runtime_get_noresume(&root_port->dev);
  }
  
  static void nvm_authenticate_complete(struct tb_switch *sw)
  {
  	struct pci_dev *root_port;
  
  	root_port = pci_find_pcie_root_port(sw->tb->nhi->pdev);
  	if (root_port)
  		pm_runtime_put(&root_port->dev);
  }
  
  static ssize_t nvm_authenticate_show(struct device *dev,
  	struct device_attribute *attr, char *buf)
  {
  	struct tb_switch *sw = tb_to_switch(dev);
  	u32 status;
  
  	nvm_get_auth_status(sw, &status);
  	return sprintf(buf, "%#x\n", status);
  }
  
  static ssize_t nvm_authenticate_store(struct device *dev,
  	struct device_attribute *attr, const char *buf, size_t count)
  {
  	struct tb_switch *sw = tb_to_switch(dev);
  	bool val;
  	int ret;
  
  	if (mutex_lock_interruptible(&switch_lock))
  		return -ERESTARTSYS;
  
  	/* If NVMem devices are not yet added */
  	if (!sw->nvm) {
  		ret = -EAGAIN;
  		goto exit_unlock;
  	}
  
  	ret = kstrtobool(buf, &val);
  	if (ret)
  		goto exit_unlock;
  
  	/* Always clear the authentication status */
  	nvm_clear_auth_status(sw);
  
  	if (val) {
  		if (!sw->nvm->buf) {
  			ret = -EINVAL;
  			goto exit_unlock;
  		}
  
  		pm_runtime_get_sync(&sw->dev);
  		ret = nvm_validate_and_write(sw);
  		if (ret) {
  			pm_runtime_mark_last_busy(&sw->dev);
  			pm_runtime_put_autosuspend(&sw->dev);
  			goto exit_unlock;
  		}
  
  		sw->nvm->authenticating = true;
  
  		if (!tb_route(sw)) {
  			/*
  			 * Keep root port from suspending as long as the
  			 * NVM upgrade process is running.
  			 */
  			nvm_authenticate_start(sw);
  			ret = nvm_authenticate_host(sw);
  			if (ret)
  				nvm_authenticate_complete(sw);
  		} else {
  			ret = nvm_authenticate_device(sw);
  		}
  		pm_runtime_mark_last_busy(&sw->dev);
  		pm_runtime_put_autosuspend(&sw->dev);
  	}
  
  exit_unlock:
  	mutex_unlock(&switch_lock);
  
  	if (ret)
  		return ret;
  	return count;
  }
  static DEVICE_ATTR_RW(nvm_authenticate);
  
  static ssize_t nvm_version_show(struct device *dev,
  				struct device_attribute *attr, char *buf)
  {
  	struct tb_switch *sw = tb_to_switch(dev);
  	int ret;
  
  	if (mutex_lock_interruptible(&switch_lock))
  		return -ERESTARTSYS;
  
  	if (sw->safe_mode)
  		ret = -ENODATA;
  	else if (!sw->nvm)
  		ret = -EAGAIN;
  	else
  		ret = sprintf(buf, "%x.%x\n", sw->nvm->major, sw->nvm->minor);
  
  	mutex_unlock(&switch_lock);
  
  	return ret;
  }
  static DEVICE_ATTR_RO(nvm_version);
  
  static ssize_t vendor_show(struct device *dev, struct device_attribute *attr,
  			   char *buf)
  {
  	struct tb_switch *sw = tb_to_switch(dev);
  
  	return sprintf(buf, "%#x\n", sw->vendor);
  }
  static DEVICE_ATTR_RO(vendor);
  
  static ssize_t
  vendor_name_show(struct device *dev, struct device_attribute *attr, char *buf)
  {
  	struct tb_switch *sw = tb_to_switch(dev);
  
  	return sprintf(buf, "%s\n", sw->vendor_name ? sw->vendor_name : "");
  }
  static DEVICE_ATTR_RO(vendor_name);
  
  static ssize_t unique_id_show(struct device *dev, struct device_attribute *attr,
  			      char *buf)
  {
  	struct tb_switch *sw = tb_to_switch(dev);
  
  	return sprintf(buf, "%pUb\n", sw->uuid);
  }
  static DEVICE_ATTR_RO(unique_id);
  
  static struct attribute *switch_attrs[] = {
  	&dev_attr_authorized.attr,
  	&dev_attr_boot.attr,
  	&dev_attr_device.attr,
  	&dev_attr_device_name.attr,
  	&dev_attr_key.attr,
  	&dev_attr_nvm_authenticate.attr,
  	&dev_attr_nvm_version.attr,
  	&dev_attr_vendor.attr,
  	&dev_attr_vendor_name.attr,
  	&dev_attr_unique_id.attr,
  	NULL,
  };
  
  static umode_t switch_attr_is_visible(struct kobject *kobj,
  				      struct attribute *attr, int n)
  {
  	struct device *dev = container_of(kobj, struct device, kobj);
  	struct tb_switch *sw = tb_to_switch(dev);
  
  	if (attr == &dev_attr_key.attr) {
  		if (tb_route(sw) &&
  		    sw->tb->security_level == TB_SECURITY_SECURE &&
  		    sw->security_level == TB_SECURITY_SECURE)
  			return attr->mode;
  		return 0;
  	} else if (attr == &dev_attr_nvm_authenticate.attr ||
  		   attr == &dev_attr_nvm_version.attr) {
  		if (sw->dma_port)
  			return attr->mode;
  		return 0;
  	} else if (attr == &dev_attr_boot.attr) {
  		if (tb_route(sw))
  			return attr->mode;
  		return 0;
  	}
  
  	return sw->safe_mode ? 0 : attr->mode;
  }
  
  static struct attribute_group switch_group = {
  	.is_visible = switch_attr_is_visible,
  	.attrs = switch_attrs,
  };
  
  static const struct attribute_group *switch_groups[] = {
  	&switch_group,
  	NULL,
  };
  
  static void tb_switch_release(struct device *dev)
  {
  	struct tb_switch *sw = tb_to_switch(dev);
  
  	dma_port_free(sw->dma_port);
  
  	kfree(sw->uuid);
  	kfree(sw->device_name);
  	kfree(sw->vendor_name);
  	kfree(sw->ports);
  	kfree(sw->drom);
  	kfree(sw->key);
  	kfree(sw);
  }
  
  /*
   * Currently only need to provide the callbacks. Everything else is handled
   * in the connection manager.
   */
  static int __maybe_unused tb_switch_runtime_suspend(struct device *dev)
  {
  	return 0;
  }
  
  static int __maybe_unused tb_switch_runtime_resume(struct device *dev)
  {
  	return 0;
  }
  
  static const struct dev_pm_ops tb_switch_pm_ops = {
  	SET_RUNTIME_PM_OPS(tb_switch_runtime_suspend, tb_switch_runtime_resume,
  			   NULL)
  };
  
  struct device_type tb_switch_type = {
  	.name = "thunderbolt_device",
  	.release = tb_switch_release,
  	.pm = &tb_switch_pm_ops,
  };
  
  static int tb_switch_get_generation(struct tb_switch *sw)
  {
  	switch (sw->config.device_id) {
  	case PCI_DEVICE_ID_INTEL_LIGHT_RIDGE:
  	case PCI_DEVICE_ID_INTEL_EAGLE_RIDGE:
  	case PCI_DEVICE_ID_INTEL_LIGHT_PEAK:
  	case PCI_DEVICE_ID_INTEL_CACTUS_RIDGE_2C:
  	case PCI_DEVICE_ID_INTEL_CACTUS_RIDGE_4C:
  	case PCI_DEVICE_ID_INTEL_PORT_RIDGE:
  	case PCI_DEVICE_ID_INTEL_REDWOOD_RIDGE_2C_BRIDGE:
  	case PCI_DEVICE_ID_INTEL_REDWOOD_RIDGE_4C_BRIDGE:
  		return 1;
  
  	case PCI_DEVICE_ID_INTEL_WIN_RIDGE_2C_BRIDGE:
  	case PCI_DEVICE_ID_INTEL_FALCON_RIDGE_2C_BRIDGE:
  	case PCI_DEVICE_ID_INTEL_FALCON_RIDGE_4C_BRIDGE:
  		return 2;
  
  	case PCI_DEVICE_ID_INTEL_ALPINE_RIDGE_LP_BRIDGE:
  	case PCI_DEVICE_ID_INTEL_ALPINE_RIDGE_2C_BRIDGE:
  	case PCI_DEVICE_ID_INTEL_ALPINE_RIDGE_4C_BRIDGE:
  	case PCI_DEVICE_ID_INTEL_ALPINE_RIDGE_C_2C_BRIDGE:
  	case PCI_DEVICE_ID_INTEL_ALPINE_RIDGE_C_4C_BRIDGE:
  	case PCI_DEVICE_ID_INTEL_TITAN_RIDGE_2C_BRIDGE:
  	case PCI_DEVICE_ID_INTEL_TITAN_RIDGE_4C_BRIDGE:
  	case PCI_DEVICE_ID_INTEL_TITAN_RIDGE_DD_BRIDGE:
  		return 3;
  
  	default:
  		/*
  		 * For unknown switches assume generation to be 1 to be
  		 * on the safe side.
  		 */
  		tb_sw_warn(sw, "unsupported switch device id %#x\n",
  			   sw->config.device_id);
  		return 1;
  	}
  }
  
  /**
   * tb_switch_alloc() - allocate a switch
   * @tb: Pointer to the owning domain
   * @parent: Parent device for this switch
   * @route: Route string for this switch
   *
   * Allocates and initializes a switch. Will not upload configuration to
   * the switch. For that you need to call tb_switch_configure()
   * separately. The returned switch should be released by calling
   * tb_switch_put().
   *
   * Return: Pointer to the allocated switch or %NULL in case of failure
   */
  struct tb_switch *tb_switch_alloc(struct tb *tb, struct device *parent,
  				  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_free_sw_ports;
  
  	tb_dbg(tb, "current 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 = 0;
  
  	/* initialize ports */
  	sw->ports = kcalloc(sw->config.max_port_number + 1, sizeof(*sw->ports),
  				GFP_KERNEL);
  	if (!sw->ports)
  		goto err_free_sw_ports;
  
  	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;
  	}
  
  	sw->generation = tb_switch_get_generation(sw);
  
  	cap = tb_switch_find_vse_cap(sw, TB_VSE_CAP_PLUG_EVENTS);
  	if (cap < 0) {
  		tb_sw_warn(sw, "cannot find TB_VSE_CAP_PLUG_EVENTS aborting\n");
  		goto err_free_sw_ports;
  	}
  	sw->cap_plug_events = cap;
  
  	/* Root switch is always authorized */
  	if (!route)
  		sw->authorized = true;
  
  	device_initialize(&sw->dev);
  	sw->dev.parent = parent;
  	sw->dev.bus = &tb_bus_type;
  	sw->dev.type = &tb_switch_type;
  	sw->dev.groups = switch_groups;
  	dev_set_name(&sw->dev, "%u-%llx", tb->index, tb_route(sw));
  
  	return sw;
  
  err_free_sw_ports:
  	kfree(sw->ports);
  	kfree(sw);
  
  	return NULL;
  }
  
  /**
   * tb_switch_alloc_safe_mode() - allocate a switch that is in safe mode
   * @tb: Pointer to the owning domain
   * @parent: Parent device for this switch
   * @route: Route string for this switch
   *
   * This creates a switch in safe mode. This means the switch pretty much
   * lacks all capabilities except DMA configuration port before it is
   * flashed with a valid NVM firmware.
   *
   * The returned switch must be released by calling tb_switch_put().
   *
   * Return: Pointer to the allocated switch or %NULL in case of failure
   */
  struct tb_switch *
  tb_switch_alloc_safe_mode(struct tb *tb, struct device *parent, u64 route)
  {
  	struct tb_switch *sw;
  
  	sw = kzalloc(sizeof(*sw), GFP_KERNEL);
  	if (!sw)
  		return NULL;
  
  	sw->tb = tb;
  	sw->config.depth = tb_route_length(route);
  	sw->config.route_hi = upper_32_bits(route);
  	sw->config.route_lo = lower_32_bits(route);
  	sw->safe_mode = true;
  
  	device_initialize(&sw->dev);
  	sw->dev.parent = parent;
  	sw->dev.bus = &tb_bus_type;
  	sw->dev.type = &tb_switch_type;
  	sw->dev.groups = switch_groups;
  	dev_set_name(&sw->dev, "%u-%llx", tb->index, tb_route(sw));
  
  	return sw;
  }
  
  /**
   * tb_switch_configure() - Uploads configuration to the switch
   * @sw: Switch to configure
   *
   * Call this function before the switch is added to the system. It will
   * upload configuration to the switch and makes it available for the
   * connection manager to use.
   *
   * Return: %0 in case of success and negative errno in case of failure
   */
  int tb_switch_configure(struct tb_switch *sw)
  {
  	struct tb *tb = sw->tb;
  	u64 route;
  	int ret;
  
  	route = tb_route(sw);
  	tb_dbg(tb, "initializing Switch at %#llx (depth: %d, up port: %d)\n",
  	       route, tb_route_length(route), sw->config.upstream_port_number);
  
  	if (sw->config.vendor_id != PCI_VENDOR_ID_INTEL)
  		tb_sw_warn(sw, "unknown switch vendor id %#x\n",
  			   sw->config.vendor_id);
  
  	sw->config.enabled = 1;
  
  	/* upload configuration */
  	ret = tb_sw_write(sw, 1 + (u32 *)&sw->config, TB_CFG_SWITCH, 1, 3);
  	if (ret)
  		return ret;
  
  	return tb_plug_events_active(sw, true);
  }
  
  static void tb_switch_set_uuid(struct tb_switch *sw)
  {
  	u32 uuid[4];
  	int cap;
  
  	if (sw->uuid)
  		return;
  
  	/*
  	 * The newer controllers include fused UUID as part of link
  	 * controller specific registers
  	 */
  	cap = tb_switch_find_vse_cap(sw, TB_VSE_CAP_LINK_CONTROLLER);
  	if (cap > 0) {
  		tb_sw_read(sw, uuid, TB_CFG_SWITCH, cap + 3, 4);
  	} else {
  		/*
  		 * ICM generates UUID based on UID and fills the upper
  		 * two words with ones. This is not strictly following
  		 * UUID format but we want to be compatible with it so
  		 * we do the same here.
  		 */
  		uuid[0] = sw->uid & 0xffffffff;
  		uuid[1] = (sw->uid >> 32) & 0xffffffff;
  		uuid[2] = 0xffffffff;
  		uuid[3] = 0xffffffff;
  	}
  
  	sw->uuid = kmemdup(uuid, sizeof(uuid), GFP_KERNEL);
  }
  
  static int tb_switch_add_dma_port(struct tb_switch *sw)
  {
  	u32 status;
  	int ret;
  
  	switch (sw->generation) {
  	case 3:
  		break;
  
  	case 2:
  		/* Only root switch can be upgraded */
  		if (tb_route(sw))
  			return 0;
  		break;
  
  	default:
  		/*
  		 * DMA port is the only thing available when the switch
  		 * is in safe mode.
  		 */
  		if (!sw->safe_mode)
  			return 0;
  		break;
  	}
  
  	if (sw->no_nvm_upgrade)
  		return 0;
  
  	sw->dma_port = dma_port_alloc(sw);
  	if (!sw->dma_port)
  		return 0;
  
  	/*
  	 * Check status of the previous flash authentication. If there
  	 * is one we need to power cycle the switch in any case to make
  	 * it functional again.
  	 */
  	ret = dma_port_flash_update_auth_status(sw->dma_port, &status);
  	if (ret <= 0)
  		return ret;
  
  	/* Now we can allow root port to suspend again */
  	if (!tb_route(sw))
  		nvm_authenticate_complete(sw);
  
  	if (status) {
  		tb_sw_info(sw, "switch flash authentication failed\n");
  		tb_switch_set_uuid(sw);
  		nvm_set_auth_status(sw, status);
  	}
  
  	tb_sw_info(sw, "power cycling the switch now\n");
  	dma_port_power_cycle(sw->dma_port);
  
  	/*
  	 * We return error here which causes the switch adding failure.
  	 * It should appear back after power cycle is complete.
  	 */
  	return -ESHUTDOWN;
  }
  
  /**
   * tb_switch_add() - Add a switch to the domain
   * @sw: Switch to add
   *
   * This is the last step in adding switch to the domain. It will read
   * identification information from DROM and initializes ports so that
   * they can be used to connect other switches. The switch will be
   * exposed to the userspace when this function successfully returns. To
   * remove and release the switch, call tb_switch_remove().
   *
   * Return: %0 in case of success and negative errno in case of failure
   */
  int tb_switch_add(struct tb_switch *sw)
  {
  	int i, ret;
  
  	/*
  	 * Initialize DMA control port now before we read DROM. Recent
  	 * host controllers have more complete DROM on NVM that includes
  	 * vendor and model identification strings which we then expose
  	 * to the userspace. NVM can be accessed through DMA
  	 * configuration based mailbox.
  	 */
  	ret = tb_switch_add_dma_port(sw);
  	if (ret)
  		return ret;
  
  	if (!sw->safe_mode) {
  		/* read drom */
  		ret = tb_drom_read(sw);
  		if (ret) {
  			tb_sw_warn(sw, "tb_eeprom_read_rom failed\n");
  			return ret;
  		}
  		tb_sw_dbg(sw, "uid: %#llx\n", sw->uid);
  
  		tb_switch_set_uuid(sw);
  
  		for (i = 0; i <= sw->config.max_port_number; i++) {
  			if (sw->ports[i].disabled) {
  				tb_port_dbg(&sw->ports[i], "disabled by eeprom\n");
  				continue;
  			}
  			ret = tb_init_port(&sw->ports[i]);
  			if (ret)
  				return ret;
  		}
  	}
  
  	ret = device_add(&sw->dev);
  	if (ret)
  		return ret;
  
  	if (tb_route(sw)) {
  		dev_info(&sw->dev, "new device found, vendor=%#x device=%#x\n",
  			 sw->vendor, sw->device);
  		if (sw->vendor_name && sw->device_name)
  			dev_info(&sw->dev, "%s %s\n", sw->vendor_name,
  				 sw->device_name);
  	}
  
  	ret = tb_switch_nvm_add(sw);
  	if (ret) {
  		device_del(&sw->dev);
  		return ret;
  	}
  
  	pm_runtime_set_active(&sw->dev);
  	if (sw->rpm) {
  		pm_runtime_set_autosuspend_delay(&sw->dev, TB_AUTOSUSPEND_DELAY);
  		pm_runtime_use_autosuspend(&sw->dev);
  		pm_runtime_mark_last_busy(&sw->dev);
  		pm_runtime_enable(&sw->dev);
  		pm_request_autosuspend(&sw->dev);
  	}
  
  	return 0;
  }
  
  /**
   * tb_switch_remove() - Remove and release a switch
   * @sw: Switch to remove
   *
   * This will remove the switch from the domain and release it after last
   * reference count drops to zero. If there are switches connected below
   * this switch, they will be removed as well.
   */
  void tb_switch_remove(struct tb_switch *sw)
  {
  	int i;
  
  	if (sw->rpm) {
  		pm_runtime_get_sync(&sw->dev);
  		pm_runtime_disable(&sw->dev);
  	}
  
  	/* 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_remove(sw->ports[i].remote->sw);
  		sw->ports[i].remote = NULL;
  		if (sw->ports[i].xdomain)
  			tb_xdomain_remove(sw->ports[i].xdomain);
  		sw->ports[i].xdomain = NULL;
  	}
  
  	if (!sw->is_unplugged)
  		tb_plug_events_active(sw, false);
  
  	tb_switch_nvm_remove(sw);
  
  	if (tb_route(sw))
  		dev_info(&sw->dev, "device disconnected\n");
  	device_unregister(&sw->dev);
  }
  
  /**
   * 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;
  	tb_sw_dbg(sw, "resuming switch\n");
  
  	/*
  	 * Check for UID of the connected switches except for root
  	 * switch which we assume cannot be removed.
  	 */
  	if (tb_route(sw)) {
  		u64 uid;
  
  		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?
  	 */
  }
  
  struct tb_sw_lookup {
  	struct tb *tb;
  	u8 link;
  	u8 depth;
  	const uuid_t *uuid;
  	u64 route;
  };
  
  static int tb_switch_match(struct device *dev, void *data)
  {
  	struct tb_switch *sw = tb_to_switch(dev);
  	struct tb_sw_lookup *lookup = data;
  
  	if (!sw)
  		return 0;
  	if (sw->tb != lookup->tb)
  		return 0;
  
  	if (lookup->uuid)
  		return !memcmp(sw->uuid, lookup->uuid, sizeof(*lookup->uuid));
  
  	if (lookup->route) {
  		return sw->config.route_lo == lower_32_bits(lookup->route) &&
  		       sw->config.route_hi == upper_32_bits(lookup->route);
  	}
  
  	/* Root switch is matched only by depth */
  	if (!lookup->depth)
  		return !sw->depth;
  
  	return sw->link == lookup->link && sw->depth == lookup->depth;
  }
  
  /**
   * tb_switch_find_by_link_depth() - Find switch by link and depth
   * @tb: Domain the switch belongs
   * @link: Link number the switch is connected
   * @depth: Depth of the switch in link
   *
   * Returned switch has reference count increased so the caller needs to
   * call tb_switch_put() when done with the switch.
   */
  struct tb_switch *tb_switch_find_by_link_depth(struct tb *tb, u8 link, u8 depth)
  {
  	struct tb_sw_lookup lookup;
  	struct device *dev;
  
  	memset(&lookup, 0, sizeof(lookup));
  	lookup.tb = tb;
  	lookup.link = link;
  	lookup.depth = depth;
  
  	dev = bus_find_device(&tb_bus_type, NULL, &lookup, tb_switch_match);
  	if (dev)
  		return tb_to_switch(dev);
  
  	return NULL;
  }
  
  /**
   * tb_switch_find_by_uuid() - Find switch by UUID
   * @tb: Domain the switch belongs
   * @uuid: UUID to look for
   *
   * Returned switch has reference count increased so the caller needs to
   * call tb_switch_put() when done with the switch.
   */
  struct tb_switch *tb_switch_find_by_uuid(struct tb *tb, const uuid_t *uuid)
  {
  	struct tb_sw_lookup lookup;
  	struct device *dev;
  
  	memset(&lookup, 0, sizeof(lookup));
  	lookup.tb = tb;
  	lookup.uuid = uuid;
  
  	dev = bus_find_device(&tb_bus_type, NULL, &lookup, tb_switch_match);
  	if (dev)
  		return tb_to_switch(dev);
  
  	return NULL;
  }
  
  /**
   * tb_switch_find_by_route() - Find switch by route string
   * @tb: Domain the switch belongs
   * @route: Route string to look for
   *
   * Returned switch has reference count increased so the caller needs to
   * call tb_switch_put() when done with the switch.
   */
  struct tb_switch *tb_switch_find_by_route(struct tb *tb, u64 route)
  {
  	struct tb_sw_lookup lookup;
  	struct device *dev;
  
  	if (!route)
  		return tb_switch_get(tb->root_switch);
  
  	memset(&lookup, 0, sizeof(lookup));
  	lookup.tb = tb;
  	lookup.route = route;
  
  	dev = bus_find_device(&tb_bus_type, NULL, &lookup, tb_switch_match);
  	if (dev)
  		return tb_to_switch(dev);
  
  	return NULL;
  }
  
  void tb_switch_exit(void)
  {
  	ida_destroy(&nvm_ida);
  }
  