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Message-ID: <PSXP216MB043843D1E5E4A65780272FB480530@PSXP216MB0438.KORP216.PROD.OUTLOOK.COM>
Date:   Wed, 18 Dec 2019 09:34:45 +0000
From:   Nicholas Johnson <nicholas.johnson-opensource@...look.com.au>
To:     Mika Westerberg <mika.westerberg@...ux.intel.com>
CC:     "linux-usb@...r.kernel.org" <linux-usb@...r.kernel.org>,
        Andreas Noever <andreas.noever@...il.com>,
        Michael Jamet <michael.jamet@...el.com>,
        Yehezkel Bernat <YehezkelShB@...il.com>,
        Rajmohan Mani <rajmohan.mani@...el.com>,
        Lukas Wunner <lukas@...ner.de>,
        Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
        Alan Stern <stern@...land.harvard.edu>,
        "Mario.Limonciello@...l.com" <Mario.Limonciello@...l.com>,
        Anthony Wong <anthony.wong@...onical.com>,
        Oliver Neukum <oneukum@...e.com>,
        Christian Kellner <ckellner@...hat.com>,
        "David S . Miller" <davem@...emloft.net>,
        "netdev@...r.kernel.org" <netdev@...r.kernel.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH v2 4/9] thunderbolt: Add initial support for USB4

On Tue, Dec 17, 2019 at 03:33:40PM +0300, Mika Westerberg wrote:
> USB4 is the public specification based on Thunderbolt 3 protocol. There
> are some differences in register layouts and flows. In addition to PCIe
> and DP tunneling, USB4 supports tunneling of USB 3.x. USB4 is also
> backward compatible with Thunderbolt 3 (and older generations but the
> spec only talks about 3rd generation). USB4 compliant devices can be
> identified by checking USB4 version field in router configuration space.
> 
> This patch adds initial support for USB4 compliant hosts and devices
> which enables following features provided by the existing functionality
> in the driver:
> 
>   - PCIe tunneling
>   - Display Port tunneling
Nitpick: DisplayPort is a single word.

>   - Host and device NVM firmware upgrade
>   - P2P networking
> 
> This brings the USB4 support to the same level that we already have for
> Thunderbolt 1, 2 and 3 devices.
> 
> Note the spec talks about host and device "routers" but in the driver we
> still use term "switch" in most places. Both can be used interchangeably.
> 
> Co-developed-by: Rajmohan Mani <rajmohan.mani@...el.com>
> Signed-off-by: Rajmohan Mani <rajmohan.mani@...el.com>
> Signed-off-by: Mika Westerberg <mika.westerberg@...ux.intel.com>
> ---
>  drivers/thunderbolt/Makefile  |   2 +-
>  drivers/thunderbolt/eeprom.c  |  53 ++-
>  drivers/thunderbolt/nhi.c     |   3 +
>  drivers/thunderbolt/nhi.h     |   2 +
>  drivers/thunderbolt/switch.c  | 382 +++++++++++++-----
>  drivers/thunderbolt/tb.c      |  20 +-
>  drivers/thunderbolt/tb.h      |  36 ++
>  drivers/thunderbolt/tb_regs.h |  36 +-
>  drivers/thunderbolt/tunnel.c  |  11 +-
>  drivers/thunderbolt/usb4.c    | 724 ++++++++++++++++++++++++++++++++++
>  drivers/thunderbolt/xdomain.c |   6 +
>  11 files changed, 1158 insertions(+), 117 deletions(-)
>  create mode 100644 drivers/thunderbolt/usb4.c
> 
> diff --git a/drivers/thunderbolt/Makefile b/drivers/thunderbolt/Makefile
> index 001187c577bf..c0b2fd73dfbd 100644
> --- a/drivers/thunderbolt/Makefile
> +++ b/drivers/thunderbolt/Makefile
> @@ -1,4 +1,4 @@
>  # SPDX-License-Identifier: GPL-2.0-only
>  obj-${CONFIG_THUNDERBOLT} := thunderbolt.o
>  thunderbolt-objs := nhi.o nhi_ops.o ctl.o tb.o switch.o cap.o path.o tunnel.o eeprom.o
> -thunderbolt-objs += domain.o dma_port.o icm.o property.o xdomain.o lc.o
> +thunderbolt-objs += domain.o dma_port.o icm.o property.o xdomain.o lc.o usb4.o
> diff --git a/drivers/thunderbolt/eeprom.c b/drivers/thunderbolt/eeprom.c
> index 540e0105bcc0..921d164b3f35 100644
> --- a/drivers/thunderbolt/eeprom.c
> +++ b/drivers/thunderbolt/eeprom.c
> @@ -487,6 +487,37 @@ static int tb_drom_copy_nvm(struct tb_switch *sw, u16 *size)
>  	return ret;
>  }
>  
> +static int usb4_copy_host_drom(struct tb_switch *sw, u16 *size)
> +{
> +	int ret;
> +
> +	ret = usb4_switch_drom_read(sw, 14, size, sizeof(*size));
> +	if (ret)
> +		return ret;
> +
> +	/* Size includes CRC8 + UID + CRC32 */
> +	*size += 1 + 8 + 4;
> +	sw->drom = kzalloc(*size, GFP_KERNEL);
> +	if (!sw->drom)
> +		return -ENOMEM;
> +
> +	ret = usb4_switch_drom_read(sw, 0, sw->drom, *size);
> +	if (ret) {
> +		kfree(sw->drom);
> +		sw->drom = NULL;
> +	}
> +
> +	return ret;
> +}
> +
> +static int tb_drom_read_n(struct tb_switch *sw, u16 offset, u8 *val,
> +			  size_t count)
> +{
> +	if (tb_switch_is_usb4(sw))
> +		return usb4_switch_drom_read(sw, offset, val, count);
> +	return tb_eeprom_read_n(sw, offset, val, count);
> +}
> +
>  /**
>   * tb_drom_read - copy drom to sw->drom and parse it
>   */
> @@ -512,14 +543,26 @@ int tb_drom_read(struct tb_switch *sw)
>  			goto parse;
>  
>  		/*
> -		 * The root switch contains only a dummy drom (header only,
> -		 * no entries). Hardcode the configuration here.
> +		 * USB4 hosts may support reading DROM through router
> +		 * operations.
>  		 */
> -		tb_drom_read_uid_only(sw, &sw->uid);
> +		if (tb_switch_is_usb4(sw)) {
> +			usb4_switch_read_uid(sw, &sw->uid);
> +			if (!usb4_copy_host_drom(sw, &size))
> +				goto parse;
> +		} else {
> +			/*
> +			 * The root switch contains only a dummy drom
> +			 * (header only, no entries). Hardcode the
> +			 * configuration here.
> +			 */
> +			tb_drom_read_uid_only(sw, &sw->uid);
> +		}
> +
>  		return 0;
>  	}
>  
> -	res = tb_eeprom_read_n(sw, 14, (u8 *) &size, 2);
> +	res = tb_drom_read_n(sw, 14, (u8 *) &size, 2);
>  	if (res)
>  		return res;
>  	size &= 0x3ff;
> @@ -533,7 +576,7 @@ int tb_drom_read(struct tb_switch *sw)
>  	sw->drom = kzalloc(size, GFP_KERNEL);
>  	if (!sw->drom)
>  		return -ENOMEM;
> -	res = tb_eeprom_read_n(sw, 0, sw->drom, size);
> +	res = tb_drom_read_n(sw, 0, sw->drom, size);
>  	if (res)
>  		goto err;
>  
> diff --git a/drivers/thunderbolt/nhi.c b/drivers/thunderbolt/nhi.c
> index 641b21b54460..1be491ecbb45 100644
> --- a/drivers/thunderbolt/nhi.c
> +++ b/drivers/thunderbolt/nhi.c
> @@ -1271,6 +1271,9 @@ static struct pci_device_id nhi_ids[] = {
>  	{ PCI_VDEVICE(INTEL, PCI_DEVICE_ID_INTEL_ICL_NHI1),
>  	  .driver_data = (kernel_ulong_t)&icl_nhi_ops },
>  
> +	/* Any USB4 compliant host */
> +	{ PCI_DEVICE_CLASS(PCI_CLASS_SERIAL_USB_USB4, ~0) },
> +
>  	{ 0,}
>  };
>  
> diff --git a/drivers/thunderbolt/nhi.h b/drivers/thunderbolt/nhi.h
> index b7b973949f8e..5d276ee9b38e 100644
> --- a/drivers/thunderbolt/nhi.h
> +++ b/drivers/thunderbolt/nhi.h
> @@ -74,4 +74,6 @@ extern const struct tb_nhi_ops icl_nhi_ops;
>  #define PCI_DEVICE_ID_INTEL_ICL_NHI1			0x8a0d
>  #define PCI_DEVICE_ID_INTEL_ICL_NHI0			0x8a17
>  
> +#define PCI_CLASS_SERIAL_USB_USB4			0x0c0340
> +
>  #endif
> diff --git a/drivers/thunderbolt/switch.c b/drivers/thunderbolt/switch.c
> index 9c72521cb298..c1d5cd7e0631 100644
> --- a/drivers/thunderbolt/switch.c
> +++ b/drivers/thunderbolt/switch.c
> @@ -163,10 +163,12 @@ static int nvm_validate_and_write(struct tb_switch *sw)
>  		image_size -= hdr_size;
>  	}
>  
> +	if (tb_switch_is_usb4(sw))
> +		return usb4_switch_nvm_write(sw, 0, buf, image_size);
>  	return dma_port_flash_write(sw->dma_port, 0, buf, image_size);
>  }
>  
> -static int nvm_authenticate_host(struct tb_switch *sw)
> +static int nvm_authenticate_host_dma_port(struct tb_switch *sw)
>  {
>  	int ret = 0;
>  
> @@ -206,7 +208,7 @@ static int nvm_authenticate_host(struct tb_switch *sw)
>  	return ret;
>  }
>  
> -static int nvm_authenticate_device(struct tb_switch *sw)
> +static int nvm_authenticate_device_dma_port(struct tb_switch *sw)
>  {
>  	int ret, retries = 10;
>  
> @@ -251,6 +253,78 @@ static int nvm_authenticate_device(struct tb_switch *sw)
>  	return -ETIMEDOUT;
>  }
>  
> +static void nvm_authenticate_start_dma_port(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_dma_port(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 inline bool nvm_readable(struct tb_switch *sw)
> +{
> +	if (tb_switch_is_usb4(sw)) {
> +		/*
> +		 * USB4 devices must support NVM operations but it is
> +		 * optional for hosts. Therefore we query the NVM sector
> +		 * size here and if it is supported assume NVM
> +		 * operations are implemented.
> +		 */
> +		return usb4_switch_nvm_sector_size(sw) > 0;
> +	}
> +
> +	/* Thunderbolt 2 and 3 devices support NVM through DMA port */
> +	return !!sw->dma_port;
> +}
> +
> +static inline bool nvm_upgradeable(struct tb_switch *sw)
> +{
> +	if (sw->no_nvm_upgrade)
> +		return false;
> +	return nvm_readable(sw);
> +}
> +
> +static inline int nvm_read(struct tb_switch *sw, unsigned int address,
> +			   void *buf, size_t size)
> +{
> +	if (tb_switch_is_usb4(sw))
> +		return usb4_switch_nvm_read(sw, address, buf, size);
> +	return dma_port_flash_read(sw->dma_port, address, buf, size);
> +}
> +
> +static int nvm_authenticate(struct tb_switch *sw)
> +{
> +	int ret;
> +
> +	if (tb_switch_is_usb4(sw))
> +		return usb4_switch_nvm_authenticate(sw);
> +
> +	if (!tb_route(sw)) {
> +		nvm_authenticate_start_dma_port(sw);
> +		ret = nvm_authenticate_host_dma_port(sw);
> +	} else {
> +		ret = nvm_authenticate_device_dma_port(sw);
> +	}
> +
> +	return ret;
> +}
> +
>  static int tb_switch_nvm_read(void *priv, unsigned int offset, void *val,
>  			      size_t bytes)
>  {
> @@ -264,7 +338,7 @@ static int tb_switch_nvm_read(void *priv, unsigned int offset, void *val,
>  		goto out;
>  	}
>  
> -	ret = dma_port_flash_read(sw->dma_port, offset, val, bytes);
> +	ret = nvm_read(sw, offset, val, bytes);
>  	mutex_unlock(&sw->tb->lock);
>  
>  out:
> @@ -341,9 +415,21 @@ static int tb_switch_nvm_add(struct tb_switch *sw)
>  	u32 val;
>  	int ret;
>  
> -	if (!sw->dma_port)
> +	if (!nvm_readable(sw))
>  		return 0;
>  
> +	/*
> +	 * The NVM format of non-Intel hardware is not known so
> +	 * currently restrict NVM upgrade for Intel hardware. We may
> +	 * relax this in the future when we learn other NVM formats.
> +	 */
> +	if (sw->config.vendor_id != PCI_VENDOR_ID_INTEL) {
> +		dev_info(&sw->dev,
> +			 "NVM format of vendor %#x is not known, disabling NVM upgrade\n",
> +			 sw->config.vendor_id);
> +		return 0;
> +	}
> +
>  	nvm = kzalloc(sizeof(*nvm), GFP_KERNEL);
>  	if (!nvm)
>  		return -ENOMEM;
> @@ -358,8 +444,7 @@ static int tb_switch_nvm_add(struct tb_switch *sw)
>  	if (!sw->safe_mode) {
>  		u32 nvm_size, hdr_size;
>  
> -		ret = dma_port_flash_read(sw->dma_port, NVM_FLASH_SIZE, &val,
> -					  sizeof(val));
> +		ret = nvm_read(sw, NVM_FLASH_SIZE, &val, sizeof(val));
>  		if (ret)
>  			goto err_ida;
>  
> @@ -367,8 +452,7 @@ static int tb_switch_nvm_add(struct tb_switch *sw)
>  		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));
> +		ret = nvm_read(sw, NVM_VERSION, &val, sizeof(val));
>  		if (ret)
>  			goto err_ida;
>  
> @@ -619,6 +703,24 @@ int tb_port_clear_counter(struct tb_port *port, int counter)
>  	return tb_port_write(port, zero, TB_CFG_COUNTERS, 3 * counter, 3);
>  }
>  
> +/**
> + * tb_port_unlock() - Unlock downstream port
> + * @port: Port to unlock
> + *
> + * Needed for USB4 but can be called for any CIO/USB4 ports. Makes the
> + * downstream router accessible for CM.
> + */
> +int tb_port_unlock(struct tb_port *port)
> +{
> +	if (tb_switch_is_icm(port->sw))
> +		return 0;
> +	if (!tb_port_is_null(port))
> +		return -EINVAL;
> +	if (tb_switch_is_usb4(port->sw))
> +		return usb4_port_unlock(port);
> +	return 0;
> +}
> +
>  /**
>   * tb_init_port() - initialize a port
>   *
> @@ -650,6 +752,10 @@ static int tb_init_port(struct tb_port *port)
>  			port->cap_phy = cap;
>  		else
>  			tb_port_WARN(port, "non switch port without a PHY\n");
> +
> +		cap = tb_port_find_cap(port, TB_PORT_CAP_USB4);
> +		if (cap > 0)
> +			port->cap_usb4 = cap;
>  	} else if (port->port != 0) {
>  		cap = tb_port_find_cap(port, TB_PORT_CAP_ADAP);
>  		if (cap > 0)
> @@ -1088,20 +1194,38 @@ int tb_dp_port_enable(struct tb_port *port, bool enable)
>  
>  /* switch utility functions */
>  
> -static void tb_dump_switch(struct tb *tb, struct tb_regs_switch_header *sw)
> +static const char *tb_switch_generation_name(const struct tb_switch *sw)
> +{
> +	switch (sw->generation) {
> +	case 1:
> +		return "Thunderbolt 1";
> +	case 2:
> +		return "Thunderbolt 2";
> +	case 3:
> +		return "Thunderbolt 3";
> +	case 4:
> +		return "USB4";
> +	default:
> +		return "Unknown";
> +	}
> +}
> +
> +static void tb_dump_switch(const struct tb *tb, const struct tb_switch *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);
> +	const struct tb_regs_switch_header *regs = &sw->config;
> +
> +	tb_dbg(tb, " %s Switch: %x:%x (Revision: %d, TB Version: %d)\n",
> +	       tb_switch_generation_name(sw), regs->vendor_id, regs->device_id,
> +	       regs->revision, regs->thunderbolt_version);
> +	tb_dbg(tb, "  Max Port Number: %d\n", regs->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);
> +	       regs->upstream_port_number, regs->depth,
> +	       (((u64) regs->route_hi) << 32) | regs->route_lo,
> +	       regs->enabled, regs->plug_events_delay);
>  	tb_dbg(tb, "   unknown1: %#x unknown4: %#x\n",
> -	       sw->__unknown1, sw->__unknown4);
> +	       regs->__unknown1, regs->__unknown4);
>  }
>  
>  /**
> @@ -1148,6 +1272,10 @@ static int tb_plug_events_active(struct tb_switch *sw, bool active)
>  	if (res)
>  		return res;
>  
> +	/* Plug events are always enabled in USB4 */
> +	if (tb_switch_is_usb4(sw))
> +		return 0;
> +
>  	res = tb_sw_read(sw, &data, TB_CFG_SWITCH, sw->cap_plug_events + 1, 1);
>  	if (res)
>  		return res;
> @@ -1359,30 +1487,6 @@ static ssize_t lanes_show(struct device *dev, struct device_attribute *attr,
>  static DEVICE_ATTR(rx_lanes, 0444, lanes_show, NULL);
>  static DEVICE_ATTR(tx_lanes, 0444, lanes_show, NULL);
>  
> -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)
>  {
> @@ -1431,17 +1535,7 @@ static ssize_t nvm_authenticate_store(struct device *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);
> -		} else {
> -			ret = nvm_authenticate_device(sw);
> -		}
> +		ret = nvm_authenticate(sw);
>  	}
>  
>  exit_unlock:
> @@ -1556,11 +1650,11 @@ static umode_t switch_attr_is_visible(struct kobject *kobj,
>  			return attr->mode;
>  		return 0;
>  	} else if (attr == &dev_attr_nvm_authenticate.attr) {
> -		if (sw->dma_port && !sw->no_nvm_upgrade)
> +		if (nvm_upgradeable(sw))
>  			return attr->mode;
>  		return 0;
>  	} else if (attr == &dev_attr_nvm_version.attr) {
> -		if (sw->dma_port)
> +		if (nvm_readable(sw))
>  			return attr->mode;
>  		return 0;
>  	} else if (attr == &dev_attr_boot.attr) {
> @@ -1672,6 +1766,9 @@ static int tb_switch_get_generation(struct tb_switch *sw)
>  		return 3;
>  
>  	default:
> +		if (tb_switch_is_usb4(sw))
> +			return 4;
> +
>  		/*
>  		 * For unknown switches assume generation to be 1 to be
>  		 * on the safe side.
> @@ -1682,6 +1779,19 @@ static int tb_switch_get_generation(struct tb_switch *sw)
>  	}
>  }
>  
> +static bool tb_switch_exceeds_max_depth(const struct tb_switch *sw, int depth)
> +{
> +	int max_depth;
> +
> +	if (tb_switch_is_usb4(sw) ||
> +	    (sw->tb->root_switch && tb_switch_is_usb4(sw->tb->root_switch)))
> +		max_depth = USB4_SWITCH_MAX_DEPTH;
> +	else
> +		max_depth = TB_SWITCH_MAX_DEPTH;
> +
> +	return depth > max_depth;
> +}
> +
>  /**
>   * tb_switch_alloc() - allocate a switch
>   * @tb: Pointer to the owning domain
> @@ -1703,10 +1813,16 @@ struct tb_switch *tb_switch_alloc(struct tb *tb, struct device *parent,
>  	int upstream_port;
>  	int i, ret, depth;
>  
> -	/* Make sure we do not exceed maximum topology limit */
> +	/* Unlock the downstream port so we can access the switch below */
> +	if (route) {
> +		struct tb_switch *parent_sw = tb_to_switch(parent);
> +		struct tb_port *down;
> +
> +		down = tb_port_at(route, parent_sw);
> +		tb_port_unlock(down);
> +	}
> +
>  	depth = tb_route_length(route);
> -	if (depth > TB_SWITCH_MAX_DEPTH)
> -		return ERR_PTR(-EADDRNOTAVAIL);
>  
>  	upstream_port = tb_cfg_get_upstream_port(tb->ctl, route);
>  	if (upstream_port < 0)
> @@ -1721,8 +1837,10 @@ struct tb_switch *tb_switch_alloc(struct tb *tb, struct device *parent,
>  	if (ret)
>  		goto err_free_sw_ports;
>  
> +	sw->generation = tb_switch_get_generation(sw);
> +
>  	tb_dbg(tb, "current switch config:\n");
> -	tb_dump_switch(tb, &sw->config);
> +	tb_dump_switch(tb, sw);
>  
>  	/* configure switch */
>  	sw->config.upstream_port_number = upstream_port;
> @@ -1731,6 +1849,10 @@ struct tb_switch *tb_switch_alloc(struct tb *tb, struct device *parent,
>  	sw->config.route_lo = lower_32_bits(route);
>  	sw->config.enabled = 0;
>  
> +	/* Make sure we do not exceed maximum topology limit */
> +	if (tb_switch_exceeds_max_depth(sw, depth))
> +		return ERR_PTR(-EADDRNOTAVAIL);
> +
>  	/* initialize ports */
>  	sw->ports = kcalloc(sw->config.max_port_number + 1, sizeof(*sw->ports),
>  				GFP_KERNEL);
> @@ -1745,14 +1867,9 @@ struct tb_switch *tb_switch_alloc(struct tb *tb, struct device *parent,
>  		sw->ports[i].port = i;
>  	}
>  
> -	sw->generation = tb_switch_get_generation(sw);
> -
>  	ret = tb_switch_find_vse_cap(sw, TB_VSE_CAP_PLUG_EVENTS);
> -	if (ret < 0) {
> -		tb_sw_warn(sw, "cannot find TB_VSE_CAP_PLUG_EVENTS aborting\n");
> -		goto err_free_sw_ports;
> -	}
> -	sw->cap_plug_events = ret;
> +	if (ret > 0)
> +		sw->cap_plug_events = ret;
>  
>  	ret = tb_switch_find_vse_cap(sw, TB_VSE_CAP_LINK_CONTROLLER);
>  	if (ret > 0)
> @@ -1823,7 +1940,8 @@ tb_switch_alloc_safe_mode(struct tb *tb, struct device *parent, u64 route)
>   *
>   * 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.
> + * connection manager to use. Can be called to the switch again after
> + * resume from low power states to re-initialize it.
>   *
>   * Return: %0 in case of success and negative errno in case of failure
>   */
> @@ -1834,21 +1952,50 @@ int tb_switch_configure(struct tb_switch *sw)
>  	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);
> +	tb_dbg(tb, "%s Switch at %#llx (depth: %d, up port: %d)\n",
> +	       sw->config.enabled ? "restoring " : "initializing", route,
> +	       tb_route_length(route), sw->config.upstream_port_number);
>  
>  	sw->config.enabled = 1;
>  
> -	/* upload configuration */
> -	ret = tb_sw_write(sw, 1 + (u32 *)&sw->config, TB_CFG_SWITCH, 1, 3);
> -	if (ret)
> -		return ret;
> +	if (tb_switch_is_usb4(sw)) {
> +		/*
> +		 * For USB4 devices, we need to program the CM version
> +		 * accordingly so that it knows to expose all the
> +		 * additional capabilities.
> +		 */
> +		sw->config.cmuv = USB4_VERSION_1_0;
> +
> +		/* Enumerate the switch */
> +		ret = tb_sw_write(sw, (u32 *)&sw->config + 1, TB_CFG_SWITCH,
> +				  ROUTER_CS_1, 4);
> +		if (ret)
> +			return ret;
>  
> -	ret = tb_lc_configure_link(sw);
> +		ret = usb4_switch_setup(sw);
> +		if (ret)
> +			return ret;
> +
> +		ret = usb4_switch_configure_link(sw);
> +	} else {
> +		if (sw->config.vendor_id != PCI_VENDOR_ID_INTEL)
> +			tb_sw_warn(sw, "unknown switch vendor id %#x\n",
> +				   sw->config.vendor_id);
> +
> +		if (!sw->cap_plug_events) {
> +			tb_sw_warn(sw, "cannot find TB_VSE_CAP_PLUG_EVENTS aborting\n");
> +			return -ENODEV;
> +		}
> +
> +		/* Enumerate the switch */
> +		ret = tb_sw_write(sw, (u32 *)&sw->config + 1, TB_CFG_SWITCH,
> +				  ROUTER_CS_1, 3);
> +		if (ret)
> +			return ret;
> +
> +		ret = tb_lc_configure_link(sw);
> +	}
>  	if (ret)
>  		return ret;
>  
> @@ -1857,18 +2004,32 @@ int tb_switch_configure(struct tb_switch *sw)
>  
>  static int tb_switch_set_uuid(struct tb_switch *sw)
>  {
> +	bool uid = false;
>  	u32 uuid[4];
>  	int ret;
>  
>  	if (sw->uuid)
>  		return 0;
>  
> -	/*
> -	 * The newer controllers include fused UUID as part of link
> -	 * controller specific registers
> -	 */
> -	ret = tb_lc_read_uuid(sw, uuid);
> -	if (ret) {
> +	if (tb_switch_is_usb4(sw)) {
> +		ret = usb4_switch_read_uid(sw, &sw->uid);
> +		if (ret)
> +			return ret;
> +		uid = true;
> +	} else {
> +		/*
> +		 * The newer controllers include fused UUID as part of
> +		 * link controller specific registers
> +		 */
> +		ret = tb_lc_read_uuid(sw, uuid);
> +		if (ret) {
> +			if (ret != -EINVAL)
> +				return ret;
> +			uid = true;
> +		}
> +	}
> +
> +	if (uid) {
>  		/*
>  		 * ICM generates UUID based on UID and fills the upper
>  		 * two words with ones. This is not strictly following
> @@ -1935,7 +2096,7 @@ static int tb_switch_add_dma_port(struct tb_switch *sw)
>  	nvm_get_auth_status(sw, &status);
>  	if (status) {
>  		if (!tb_route(sw))
> -			nvm_authenticate_complete(sw);
> +			nvm_authenticate_complete_dma_port(sw);
>  		return 0;
>  	}
>  
> @@ -1950,7 +2111,7 @@ static int tb_switch_add_dma_port(struct tb_switch *sw)
>  
>  	/* Now we can allow root port to suspend again */
>  	if (!tb_route(sw))
> -		nvm_authenticate_complete(sw);
> +		nvm_authenticate_complete_dma_port(sw);
>  
>  	if (status) {
>  		tb_sw_info(sw, "switch flash authentication failed\n");
> @@ -2004,6 +2165,8 @@ static bool tb_switch_lane_bonding_possible(struct tb_switch *sw)
>  	if (!up->dual_link_port || !up->dual_link_port->remote)
>  		return false;
>  
> +	if (tb_switch_is_usb4(sw))
> +		return usb4_switch_lane_bonding_possible(sw);
>  	return tb_lc_lane_bonding_possible(sw);
>  }
>  
> @@ -2240,7 +2403,11 @@ void tb_switch_remove(struct tb_switch *sw)
>  
>  	if (!sw->is_unplugged)
>  		tb_plug_events_active(sw, false);
> -	tb_lc_unconfigure_link(sw);
> +
> +	if (tb_switch_is_usb4(sw))
> +		usb4_switch_unconfigure_link(sw);
> +	else
> +		tb_lc_unconfigure_link(sw);
>  
>  	tb_switch_nvm_remove(sw);
>  
> @@ -2298,7 +2465,10 @@ int tb_switch_resume(struct tb_switch *sw)
>  			return err;
>  		}
>  
> -		err = tb_drom_read_uid_only(sw, &uid);
> +		if (tb_switch_is_usb4(sw))
> +			err = usb4_switch_read_uid(sw, &uid);
> +		else
> +			err = tb_drom_read_uid_only(sw, &uid);
>  		if (err) {
>  			tb_sw_warn(sw, "uid read failed\n");
>  			return err;
> @@ -2311,16 +2481,7 @@ int tb_switch_resume(struct tb_switch *sw)
>  		}
>  	}
>  
> -	/* upload configuration */
> -	err = tb_sw_write(sw, 1 + (u32 *) &sw->config, TB_CFG_SWITCH, 1, 3);
> -	if (err)
> -		return err;
> -
> -	err = tb_lc_configure_link(sw);
> -	if (err)
> -		return err;
> -
> -	err = tb_plug_events_active(sw, true);
> +	err = tb_switch_configure(sw);
>  	if (err)
>  		return err;
>  
> @@ -2336,8 +2497,14 @@ int tb_switch_resume(struct tb_switch *sw)
>  				tb_sw_set_unplugged(port->remote->sw);
>  			else if (port->xdomain)
>  				port->xdomain->is_unplugged = true;
> -		} else if (tb_port_has_remote(port)) {
> -			if (tb_switch_resume(port->remote->sw)) {
> +		} else if (tb_port_has_remote(port) || port->xdomain) {
> +			/*
> +			 * Always unlock the port so the downstream
> +			 * switch/domain is accessible.
> +			 */
> +			if (tb_port_unlock(port))
> +				tb_port_warn(port, "failed to unlock port\n");
> +			if (port->remote && tb_switch_resume(port->remote->sw)) {
>  				tb_port_warn(port,
>  					     "lost during suspend, disconnecting\n");
>  				tb_sw_set_unplugged(port->remote->sw);
> @@ -2361,7 +2528,10 @@ void tb_switch_suspend(struct tb_switch *sw)
>  			tb_switch_suspend(port->remote->sw);
>  	}
>  
> -	tb_lc_set_sleep(sw);
> +	if (tb_switch_is_usb4(sw))
> +		usb4_switch_set_sleep(sw);
> +	else
> +		tb_lc_set_sleep(sw);
>  }
>  
>  /**
> @@ -2374,6 +2544,8 @@ void tb_switch_suspend(struct tb_switch *sw)
>   */
>  bool tb_switch_query_dp_resource(struct tb_switch *sw, struct tb_port *in)
>  {
> +	if (tb_switch_is_usb4(sw))
> +		return usb4_switch_query_dp_resource(sw, in);
>  	return tb_lc_dp_sink_query(sw, in);
>  }
>  
> @@ -2388,6 +2560,8 @@ bool tb_switch_query_dp_resource(struct tb_switch *sw, struct tb_port *in)
>   */
>  int tb_switch_alloc_dp_resource(struct tb_switch *sw, struct tb_port *in)
>  {
> +	if (tb_switch_is_usb4(sw))
> +		return usb4_switch_alloc_dp_resource(sw, in);
>  	return tb_lc_dp_sink_alloc(sw, in);
>  }
>  
> @@ -2401,10 +2575,16 @@ int tb_switch_alloc_dp_resource(struct tb_switch *sw, struct tb_port *in)
>   */
>  void tb_switch_dealloc_dp_resource(struct tb_switch *sw, struct tb_port *in)
>  {
> -	if (tb_lc_dp_sink_dealloc(sw, in)) {
> +	int ret;
> +
> +	if (tb_switch_is_usb4(sw))
> +		ret = usb4_switch_dealloc_dp_resource(sw, in);
> +	else
> +		ret = tb_lc_dp_sink_dealloc(sw, in);
> +
> +	if (ret)
>  		tb_sw_warn(sw, "failed to de-allocate DP resource for port %d\n",
>  			   in->port);
> -	}
>  }
>  
>  struct tb_sw_lookup {
> diff --git a/drivers/thunderbolt/tb.c b/drivers/thunderbolt/tb.c
> index e54d0d89a32d..6b99dcd1790c 100644
> --- a/drivers/thunderbolt/tb.c
> +++ b/drivers/thunderbolt/tb.c
> @@ -365,12 +365,15 @@ static struct tb_port *tb_find_unused_port(struct tb_switch *sw,
>  static struct tb_port *tb_find_pcie_down(struct tb_switch *sw,
>  					 const struct tb_port *port)
>  {
> +	struct tb_port *down = NULL;
> +
>  	/*
>  	 * To keep plugging devices consistently in the same PCIe
> -	 * hierarchy, do mapping here for root switch downstream PCIe
> -	 * ports.
> +	 * hierarchy, do mapping here for switch downstream PCIe ports.
>  	 */
> -	if (!tb_route(sw)) {
> +	if (tb_switch_is_usb4(sw)) {
> +		down = usb4_switch_map_pcie_down(sw, port);
> +	} else if (!tb_route(sw)) {
>  		int phy_port = tb_phy_port_from_link(port->port);
>  		int index;
>  
> @@ -391,12 +394,17 @@ static struct tb_port *tb_find_pcie_down(struct tb_switch *sw,
>  		/* Validate the hard-coding */
>  		if (WARN_ON(index > sw->config.max_port_number))
>  			goto out;
> -		if (WARN_ON(!tb_port_is_pcie_down(&sw->ports[index])))
> +
> +		down = &sw->ports[index];
> +	}
> +
> +	if (down) {
> +		if (WARN_ON(!tb_port_is_pcie_down(down)))
>  			goto out;
> -		if (WARN_ON(tb_pci_port_is_enabled(&sw->ports[index])))
> +		if (WARN_ON(tb_pci_port_is_enabled(down)))
>  			goto out;
>  
> -		return &sw->ports[index];
> +		return down;
>  	}
>  
>  out:
> diff --git a/drivers/thunderbolt/tb.h b/drivers/thunderbolt/tb.h
> index ade1c7c77db1..0158f0e9858c 100644
> --- a/drivers/thunderbolt/tb.h
> +++ b/drivers/thunderbolt/tb.h
> @@ -44,6 +44,7 @@ struct tb_switch_nvm {
>  
>  #define TB_SWITCH_KEY_SIZE		32
>  #define TB_SWITCH_MAX_DEPTH		6
> +#define USB4_SWITCH_MAX_DEPTH		5
>  
>  /**
>   * struct tb_switch - a thunderbolt switch
> @@ -129,6 +130,7 @@ struct tb_switch {
>   * @xdomain: Remote host (%NULL if not connected)
>   * @cap_phy: Offset, zero if not found
>   * @cap_adap: Offset of the adapter specific capability (%0 if not present)
> + * @cap_usb4: Offset to the USB4 port capability (%0 if not present)
>   * @port: Port number on switch
>   * @disabled: Disabled by eeprom
>   * @bonded: true if the port is bonded (two lanes combined as one)
> @@ -146,6 +148,7 @@ struct tb_port {
>  	struct tb_xdomain *xdomain;
>  	int cap_phy;
>  	int cap_adap;
> +	int cap_usb4;
>  	u8 port;
>  	bool disabled;
>  	bool bonded;
> @@ -637,6 +640,17 @@ static inline bool tb_switch_is_titan_ridge(const struct tb_switch *sw)
>  	}
>  }
>  
> +/**
> + * tb_switch_is_usb4() - Is the switch USB4 compliant
> + * @sw: Switch to check
> + *
> + * Returns true if the @sw is USB4 compliant router, false otherwise.
> + */
> +static inline bool tb_switch_is_usb4(const struct tb_switch *sw)
> +{
> +	return sw->config.thunderbolt_version == USB4_VERSION_1_0;
> +}
> +
>  /**
>   * tb_switch_is_icm() - Is the switch handled by ICM firmware
>   * @sw: Switch to check
> @@ -662,6 +676,7 @@ int tb_wait_for_port(struct tb_port *port, bool wait_if_unplugged);
>  int tb_port_add_nfc_credits(struct tb_port *port, int credits);
>  int tb_port_set_initial_credits(struct tb_port *port, u32 credits);
>  int tb_port_clear_counter(struct tb_port *port, int counter);
> +int tb_port_unlock(struct tb_port *port);
>  int tb_port_alloc_in_hopid(struct tb_port *port, int hopid, int max_hopid);
>  void tb_port_release_in_hopid(struct tb_port *port, int hopid);
>  int tb_port_alloc_out_hopid(struct tb_port *port, int hopid, int max_hopid);
> @@ -736,4 +751,25 @@ void tb_xdomain_remove(struct tb_xdomain *xd);
>  struct tb_xdomain *tb_xdomain_find_by_link_depth(struct tb *tb, u8 link,
>  						 u8 depth);
>  
> +int usb4_switch_setup(struct tb_switch *sw);
> +int usb4_switch_read_uid(struct tb_switch *sw, u64 *uid);
> +int usb4_switch_drom_read(struct tb_switch *sw, unsigned int address, void *buf,
> +			  size_t size);
> +int usb4_switch_configure_link(struct tb_switch *sw);
> +void usb4_switch_unconfigure_link(struct tb_switch *sw);
> +bool usb4_switch_lane_bonding_possible(struct tb_switch *sw);
> +int usb4_switch_set_sleep(struct tb_switch *sw);
> +int usb4_switch_nvm_sector_size(struct tb_switch *sw);
> +int usb4_switch_nvm_read(struct tb_switch *sw, unsigned int address, void *buf,
> +			 size_t size);
> +int usb4_switch_nvm_write(struct tb_switch *sw, unsigned int address,
> +			  const void *buf, size_t size);
> +int usb4_switch_nvm_authenticate(struct tb_switch *sw);
> +bool usb4_switch_query_dp_resource(struct tb_switch *sw, struct tb_port *in);
> +int usb4_switch_alloc_dp_resource(struct tb_switch *sw, struct tb_port *in);
> +int usb4_switch_dealloc_dp_resource(struct tb_switch *sw, struct tb_port *in);
> +struct tb_port *usb4_switch_map_pcie_down(struct tb_switch *sw,
> +					  const struct tb_port *port);
> +
> +int usb4_port_unlock(struct tb_port *port);
>  #endif
> diff --git a/drivers/thunderbolt/tb_regs.h b/drivers/thunderbolt/tb_regs.h
> index 7ee45b73c7f7..47f73f992412 100644
> --- a/drivers/thunderbolt/tb_regs.h
> +++ b/drivers/thunderbolt/tb_regs.h
> @@ -41,6 +41,7 @@ enum tb_port_cap {
>  	TB_PORT_CAP_TIME1		= 0x03,
>  	TB_PORT_CAP_ADAP		= 0x04,
>  	TB_PORT_CAP_VSE			= 0x05,
> +	TB_PORT_CAP_USB4		= 0x06,
>  };
>  
>  enum tb_port_state {
> @@ -164,10 +165,36 @@ struct tb_regs_switch_header {
>  				  * milliseconds. Writing 0x00 is interpreted
>  				  * as 255ms.
>  				  */
> -	u32 __unknown4:16;
> +	u32 cmuv:8;
> +	u32 __unknown4:8;
>  	u32 thunderbolt_version:8;
>  } __packed;
>  
> +/* USB4 version 1.0 */
> +#define USB4_VERSION_1_0			0x20
> +
> +#define ROUTER_CS_1				0x01
> +#define ROUTER_CS_4				0x04
> +#define ROUTER_CS_5				0x05
> +#define ROUTER_CS_5_SLP				BIT(0)
> +#define ROUTER_CS_5_C3S				BIT(23)
> +#define ROUTER_CS_5_PTO				BIT(24)
> +#define ROUTER_CS_5_HCO				BIT(26)
> +#define ROUTER_CS_5_CV				BIT(31)
> +#define ROUTER_CS_6				0x06
> +#define ROUTER_CS_6_SLPR			BIT(0)
> +#define ROUTER_CS_6_TNS				BIT(1)
> +#define ROUTER_CS_6_HCI				BIT(18)
> +#define ROUTER_CS_6_CR				BIT(25)
> +#define ROUTER_CS_7				0x07
> +#define ROUTER_CS_9				0x09
> +#define ROUTER_CS_25				0x19
> +#define ROUTER_CS_26				0x1a
> +#define ROUTER_CS_26_STATUS_MASK		GENMASK(29, 24)
> +#define ROUTER_CS_26_STATUS_SHIFT		24
> +#define ROUTER_CS_26_ONS			BIT(30)
> +#define ROUTER_CS_26_OV				BIT(31)
> +
>  enum tb_port_type {
>  	TB_TYPE_INACTIVE	= 0x000000,
>  	TB_TYPE_PORT		= 0x000001,
> @@ -216,6 +243,7 @@ struct tb_regs_port_header {
>  #define ADP_CS_4_NFC_BUFFERS_MASK		GENMASK(9, 0)
>  #define ADP_CS_4_TOTAL_BUFFERS_MASK		GENMASK(29, 20)
>  #define ADP_CS_4_TOTAL_BUFFERS_SHIFT		20
> +#define ADP_CS_4_LCK				BIT(31)
>  #define ADP_CS_5				0x05
>  #define ADP_CS_5_LCA_MASK			GENMASK(28, 22)
>  #define ADP_CS_5_LCA_SHIFT			22
> @@ -237,6 +265,12 @@ struct tb_regs_port_header {
>  #define LANE_ADP_CS_1_CURRENT_WIDTH_MASK	GENMASK(25, 20)
>  #define LANE_ADP_CS_1_CURRENT_WIDTH_SHIFT	20
>  
> +/* USB4 port registers */
> +#define PORT_CS_18				0x12
> +#define PORT_CS_18_BE				BIT(8)
> +#define PORT_CS_19				0x13
> +#define PORT_CS_19_PC				BIT(3)
> +
>  /* Display Port adapter registers */
Nitpick: DisplayPort is a single word.

>  #define ADP_DP_CS_0				0x00
>  #define ADP_DP_CS_0_VIDEO_HOPID_MASK		GENMASK(26, 16)
> diff --git a/drivers/thunderbolt/tunnel.c b/drivers/thunderbolt/tunnel.c
> index 0d3463c4e24a..21d266a76b7d 100644
> --- a/drivers/thunderbolt/tunnel.c
> +++ b/drivers/thunderbolt/tunnel.c
> @@ -243,6 +243,12 @@ struct tb_tunnel *tb_tunnel_alloc_pci(struct tb *tb, struct tb_port *up,
>  	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;
> @@ -250,8 +256,7 @@ static int tb_dp_cm_handshake(struct tb_port *in, struct tb_port *out)
>  	int ret;
>  
>  	/* Both ends need to support this */
> -	if (!tb_switch_is_titan_ridge(in->sw) ||
> -	    !tb_switch_is_titan_ridge(out->sw))
> +	if (!tb_dp_is_usb4(in->sw) || !tb_dp_is_usb4(out->sw))
>  		return 0;
>  
>  	ret = tb_port_read(out, &val, TB_CFG_PORT,
> @@ -531,7 +536,7 @@ static int tb_dp_consumed_bandwidth(struct tb_tunnel *tunnel)
>  	u32 val, rate = 0, lanes = 0;
>  	int ret;
>  
> -	if (tb_switch_is_titan_ridge(sw)) {
> +	if (tb_dp_is_usb4(sw)) {
>  		int timeout = 10;
>  
>  		/*
> diff --git a/drivers/thunderbolt/usb4.c b/drivers/thunderbolt/usb4.c
> new file mode 100644
> index 000000000000..b84c74346d2b
> --- /dev/null
> +++ b/drivers/thunderbolt/usb4.c
> @@ -0,0 +1,724 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * USB4 specific functionality
> + *
> + * Copyright (C) 2019, Intel Corporation
> + * Authors: Mika Westerberg <mika.westerberg@...ux.intel.com>
> + *	    Rajmohan Mani <rajmohan.mani@...el.com>
> + */
> +
> +#include <linux/delay.h>
> +#include <linux/ktime.h>
> +
> +#include "tb.h"
> +
> +#define USB4_DATA_DWORDS		16
> +#define USB4_DATA_RETRIES		3
> +
> +enum usb4_switch_op {
> +	USB4_SWITCH_OP_QUERY_DP_RESOURCE = 0x10,
> +	USB4_SWITCH_OP_ALLOC_DP_RESOURCE = 0x11,
> +	USB4_SWITCH_OP_DEALLOC_DP_RESOURCE = 0x12,
> +	USB4_SWITCH_OP_NVM_WRITE = 0x20,
> +	USB4_SWITCH_OP_NVM_AUTH = 0x21,
> +	USB4_SWITCH_OP_NVM_READ = 0x22,
> +	USB4_SWITCH_OP_NVM_SET_OFFSET = 0x23,
> +	USB4_SWITCH_OP_DROM_READ = 0x24,
> +	USB4_SWITCH_OP_NVM_SECTOR_SIZE = 0x25,
> +};
> +
> +#define USB4_NVM_READ_OFFSET_MASK	GENMASK(23, 2)
> +#define USB4_NVM_READ_OFFSET_SHIFT	2
> +#define USB4_NVM_READ_LENGTH_MASK	GENMASK(27, 24)
> +#define USB4_NVM_READ_LENGTH_SHIFT	24
> +
> +#define USB4_NVM_SET_OFFSET_MASK	USB4_NVM_READ_OFFSET_MASK
> +#define USB4_NVM_SET_OFFSET_SHIFT	USB4_NVM_READ_OFFSET_SHIFT
> +
> +#define USB4_DROM_ADDRESS_MASK		GENMASK(14, 2)
> +#define USB4_DROM_ADDRESS_SHIFT		2
> +#define USB4_DROM_SIZE_MASK		GENMASK(19, 15)
> +#define USB4_DROM_SIZE_SHIFT		15
> +
> +#define USB4_NVM_SECTOR_SIZE_MASK	GENMASK(23, 0)
> +
> +typedef int (*read_block_fn)(struct tb_switch *, unsigned int, void *, size_t);
> +typedef int (*write_block_fn)(struct tb_switch *, const void *, size_t);
> +
> +static int usb4_switch_wait_for_bit(struct tb_switch *sw, u32 offset, u32 bit,
> +				    u32 value, int timeout_msec)
> +{
> +	ktime_t timeout = ktime_add_ms(ktime_get(), timeout_msec);
> +
> +	do {
> +		u32 val;
> +		int ret;
> +
> +		ret = tb_sw_read(sw, &val, TB_CFG_SWITCH, offset, 1);
> +		if (ret)
> +			return ret;
> +
> +		if ((val & bit) == value)
> +			return 0;
> +
> +		usleep_range(50, 100);
> +	} while (ktime_before(ktime_get(), timeout));
> +
> +	return -ETIMEDOUT;
> +}
> +
> +static int usb4_switch_op_read_data(struct tb_switch *sw, void *data,
> +				    size_t dwords)
> +{
> +	if (dwords > USB4_DATA_DWORDS)
> +		return -EINVAL;
> +
> +	return tb_sw_read(sw, data, TB_CFG_SWITCH, ROUTER_CS_9, dwords);
> +}
> +
> +static int usb4_switch_op_write_data(struct tb_switch *sw, const void *data,
> +				     size_t dwords)
> +{
> +	if (dwords > USB4_DATA_DWORDS)
> +		return -EINVAL;
> +
> +	return tb_sw_write(sw, data, TB_CFG_SWITCH, ROUTER_CS_9, dwords);
> +}
> +
> +static int usb4_switch_op_read_metadata(struct tb_switch *sw, u32 *metadata)
> +{
> +	return tb_sw_read(sw, metadata, TB_CFG_SWITCH, ROUTER_CS_25, 1);
> +}
> +
> +static int usb4_switch_op_write_metadata(struct tb_switch *sw, u32 metadata)
> +{
> +	return tb_sw_write(sw, &metadata, TB_CFG_SWITCH, ROUTER_CS_25, 1);
> +}
> +
> +static int usb4_switch_do_read_data(struct tb_switch *sw, u16 address,
> +	void *buf, size_t size, read_block_fn read_block)
> +{
> +	unsigned int retries = USB4_DATA_RETRIES;
> +	unsigned int offset;
> +
> +	offset = address & 3;
> +	address = address & ~3;
> +
> +	do {
> +		size_t nbytes = min_t(size_t, size, USB4_DATA_DWORDS * 4);
> +		unsigned int dwaddress, dwords;
> +		u8 data[USB4_DATA_DWORDS * 4];
> +		int ret;
> +
> +		dwaddress = address / 4;
> +		dwords = ALIGN(nbytes, 4) / 4;
> +
> +		ret = read_block(sw, dwaddress, data, dwords);
> +		if (ret) {
> +			if (ret == -ETIMEDOUT) {
> +				if (retries--)
> +					continue;
> +				ret = -EIO;
> +			}
> +			return ret;
> +		}
> +
> +		memcpy(buf, data + offset, nbytes);
> +
> +		size -= nbytes;
> +		address += nbytes;
> +		buf += nbytes;
> +	} while (size > 0);
> +
> +	return 0;
> +}
> +
> +static int usb4_switch_do_write_data(struct tb_switch *sw, u16 address,
> +	const void *buf, size_t size, write_block_fn write_next_block)
> +{
> +	unsigned int retries = USB4_DATA_RETRIES;
> +	unsigned int offset;
> +
> +	offset = address & 3;
> +	address = address & ~3;
> +
> +	do {
> +		u32 nbytes = min_t(u32, size, USB4_DATA_DWORDS * 4);
> +		u8 data[USB4_DATA_DWORDS * 4];
> +		int ret;
> +
> +		memcpy(data + offset, buf, nbytes);
> +
> +		ret = write_next_block(sw, data, nbytes / 4);
> +		if (ret) {
> +			if (ret == -ETIMEDOUT) {
> +				if (retries--)
> +					continue;
> +				ret = -EIO;
> +			}
> +			return ret;
> +		}
> +
> +		size -= nbytes;
> +		address += nbytes;
> +		buf += nbytes;
> +	} while (size > 0);
> +
> +	return 0;
> +}
> +
> +static int usb4_switch_op(struct tb_switch *sw, u16 opcode, u8 *status)
> +{
> +	u32 val;
> +	int ret;
> +
> +	val = opcode | ROUTER_CS_26_OV;
> +	ret = tb_sw_write(sw, &val, TB_CFG_SWITCH, ROUTER_CS_26, 1);
> +	if (ret)
> +		return ret;
> +
> +	ret = usb4_switch_wait_for_bit(sw, ROUTER_CS_26, ROUTER_CS_26_OV, 0, 500);
> +	if (ret)
> +		return ret;
> +
> +	ret = tb_sw_read(sw, &val, TB_CFG_SWITCH, ROUTER_CS_26, 1);
> +	if (val & ROUTER_CS_26_ONS)
> +		return -EOPNOTSUPP;
> +
> +	*status = (val & ROUTER_CS_26_STATUS_MASK) >> ROUTER_CS_26_STATUS_SHIFT;
> +	return 0;
> +}
> +
> +/**
> + * usb4_switch_setup() - Additional setup for USB4 device
> + * @sw: USB4 router to setup
> + *
> + * USB4 routers need additional settings in order to enable all the
> + * tunneling. This function enables USB and PCIe tunneling if it can be
> + * enabled (e.g the parent switch also supports them). If USB tunneling
> + * is not available for some reason (like that there is Thunderbolt 3
> + * switch upstream) then the internal xHCI controller is enabled
> + * instead.
> + */
> +int usb4_switch_setup(struct tb_switch *sw)
> +{
> +	struct tb_switch *parent;
> +	bool tbt3, xhci;
> +	u32 val = 0;
> +	int ret;
> +
> +	if (!tb_route(sw))
> +		return 0;
> +
> +	ret = tb_sw_read(sw, &val, TB_CFG_SWITCH, ROUTER_CS_6, 1);
> +	if (ret)
> +		return ret;
> +
> +	xhci = val & ROUTER_CS_6_HCI;
> +	tbt3 = !(val & ROUTER_CS_6_TNS);
> +
> +	tb_sw_dbg(sw, "TBT3 support: %s, xHCI: %s\n",
> +		  tbt3 ? "yes" : "no", xhci ? "yes" : "no");
> +
> +	ret = tb_sw_read(sw, &val, TB_CFG_SWITCH, ROUTER_CS_5, 1);
> +	if (ret)
> +		return ret;
> +
> +	parent = tb_switch_parent(sw);
> +
> +	/* Only enable PCIe tunneling if the parent router supports it */
> +	if (tb_switch_find_port(parent, TB_TYPE_PCIE_DOWN)) {
> +		val |= ROUTER_CS_5_PTO;
> +		/* xHCI can be enabled if PCIe tunneling is supported */
> +		if (xhci & ROUTER_CS_6_HCI)
> +			val |= ROUTER_CS_5_HCO;
> +	}
> +
> +	/* TBT3 supported by the CM */
> +	val |= ROUTER_CS_5_C3S;
> +	/* Tunneling configuration is ready now */
> +	val |= ROUTER_CS_5_CV;
> +
> +	ret = tb_sw_write(sw, &val, TB_CFG_SWITCH, ROUTER_CS_5, 1);
> +	if (ret)
> +		return ret;
> +
> +	return usb4_switch_wait_for_bit(sw, ROUTER_CS_6, ROUTER_CS_6_CR,
> +					ROUTER_CS_6_CR, 50);
> +}
> +
> +/**
> + * usb4_switch_read_uid() - Read UID from USB4 router
> + * @sw: USB4 router
> + *
> + * Reads 64-bit UID from USB4 router config space.
> + */
> +int usb4_switch_read_uid(struct tb_switch *sw, u64 *uid)
> +{
> +	return tb_sw_read(sw, uid, TB_CFG_SWITCH, ROUTER_CS_7, 2);
> +}
> +
> +static int usb4_switch_drom_read_block(struct tb_switch *sw,
> +				       unsigned int dwaddress, void *buf,
> +				       size_t dwords)
> +{
> +	u8 status = 0;
> +	u32 metadata;
> +	int ret;
> +
> +	metadata = (dwords << USB4_DROM_SIZE_SHIFT) & USB4_DROM_SIZE_MASK;
> +	metadata |= (dwaddress << USB4_DROM_ADDRESS_SHIFT) &
> +		USB4_DROM_ADDRESS_MASK;
> +
> +	ret = usb4_switch_op_write_metadata(sw, metadata);
> +	if (ret)
> +		return ret;
> +
> +	ret = usb4_switch_op(sw, USB4_SWITCH_OP_DROM_READ, &status);
> +	if (ret)
> +		return ret;
> +
> +	if (status)
> +		return -EIO;
> +
> +	return usb4_switch_op_read_data(sw, buf, dwords);
> +}
> +
> +/**
> + * usb4_switch_drom_read() - Read arbitrary bytes from USB4 router DROM
> + * @sw: USB4 router
> + *
> + * Uses USB4 router operations to read router DROM. For devices this
> + * should always work but for hosts it may return %-EOPNOTSUPP in which
> + * case the host router does not have DROM.
> + */
> +int usb4_switch_drom_read(struct tb_switch *sw, unsigned int address, void *buf,
> +			  size_t size)
> +{
> +	return usb4_switch_do_read_data(sw, address, buf, size,
> +					usb4_switch_drom_read_block);
> +}
> +
> +static int usb4_set_port_configured(struct tb_port *port, bool configured)
> +{
> +	int ret;
> +	u32 val;
> +
> +	ret = tb_port_read(port, &val, TB_CFG_PORT,
> +			   port->cap_usb4 + PORT_CS_19, 1);
> +	if (ret)
> +		return ret;
> +
> +	if (configured)
> +		val |= PORT_CS_19_PC;
> +	else
> +		val &= ~PORT_CS_19_PC;
> +
> +	return tb_port_write(port, &val, TB_CFG_PORT,
> +			     port->cap_usb4 + PORT_CS_19, 1);
> +}
> +
> +/**
> + * usb4_switch_configure_link() - Set upstream USB4 link configured
> + * @sw: USB4 router
> + *
> + * Sets the upstream USB4 link to be configured for power management
> + * purposes.
> + */
> +int usb4_switch_configure_link(struct tb_switch *sw)
> +{
> +	struct tb_port *up;
> +
> +	if (!tb_route(sw))
> +		return 0;
> +
> +	up = tb_upstream_port(sw);
> +	return usb4_set_port_configured(up, true);
> +}
> +
> +/**
> + * usb4_switch_unconfigure_link() - Un-set upstream USB4 link configuration
> + * @sw: USB4 router
> + *
> + * Reverse of usb4_switch_configure_link().
> + */
> +void usb4_switch_unconfigure_link(struct tb_switch *sw)
> +{
> +	struct tb_port *up;
> +
> +	if (sw->is_unplugged || !tb_route(sw))
> +		return;
> +
> +	up = tb_upstream_port(sw);
> +	usb4_set_port_configured(up, false);
> +}
> +
> +/**
> + * usb4_switch_lane_bonding_possible() - Are conditions met for lane bonding
> + * @sw: USB4 router
> + *
> + * Checks whether conditions are met so that lane bonding can be
> + * established with the upstream router. Call only for device routers.
> + */
> +bool usb4_switch_lane_bonding_possible(struct tb_switch *sw)
> +{
> +	struct tb_port *up;
> +	int ret;
> +	u32 val;
> +
> +	up = tb_upstream_port(sw);
> +	ret = tb_port_read(up, &val, TB_CFG_PORT, up->cap_usb4 + PORT_CS_18, 1);
> +	if (ret)
> +		return false;
> +
> +	return !!(val & PORT_CS_18_BE);
> +}
> +
> +/**
> + * usb4_switch_set_sleep() - Prepare the router to enter sleep
> + * @sw: USB4 router
> + *
> + * Enables wakes and sets sleep bit for the router. Returns when the
> + * router sleep ready bit has been asserted.
> + */
> +int usb4_switch_set_sleep(struct tb_switch *sw)
> +{
> +	int ret;
> +	u32 val;
> +
> +	/* Set sleep bit and wait for sleep ready to be asserted */
> +	ret = tb_sw_read(sw, &val, TB_CFG_SWITCH, ROUTER_CS_5, 1);
> +	if (ret)
> +		return ret;
> +
> +	val |= ROUTER_CS_5_SLP;
> +
> +	ret = tb_sw_write(sw, &val, TB_CFG_SWITCH, ROUTER_CS_5, 1);
> +	if (ret)
> +		return ret;
> +
> +	return usb4_switch_wait_for_bit(sw, ROUTER_CS_6, ROUTER_CS_6_SLPR,
> +					ROUTER_CS_6_SLPR, 500);
> +}
> +
> +/**
> + * usb4_switch_nvm_sector_size() - Return router NVM sector size
> + * @sw: USB4 router
> + *
> + * If the router supports NVM operations this function returns the NVM
> + * sector size in bytes. If NVM operations are not supported returns
> + * %-EOPNOTSUPP.
> + */
> +int usb4_switch_nvm_sector_size(struct tb_switch *sw)
> +{
> +	u32 metadata;
> +	u8 status;
> +	int ret;
> +
> +	ret = usb4_switch_op(sw, USB4_SWITCH_OP_NVM_SECTOR_SIZE, &status);
> +	if (ret)
> +		return ret;
> +
> +	if (status)
> +		return status == 0x2 ? -EOPNOTSUPP : -EIO;
> +
> +	ret = usb4_switch_op_read_metadata(sw, &metadata);
> +	if (ret)
> +		return ret;
> +
> +	return metadata & USB4_NVM_SECTOR_SIZE_MASK;
> +}
> +
> +static int usb4_switch_nvm_read_block(struct tb_switch *sw,
> +	unsigned int dwaddress, void *buf, size_t dwords)
> +{
> +	u8 status = 0;
> +	u32 metadata;
> +	int ret;
> +
> +	metadata = (dwords << USB4_NVM_READ_LENGTH_SHIFT) &
> +		   USB4_NVM_READ_LENGTH_MASK;
> +	metadata |= (dwaddress << USB4_NVM_READ_OFFSET_SHIFT) &
> +		   USB4_NVM_READ_OFFSET_MASK;
> +
> +	ret = usb4_switch_op_write_metadata(sw, metadata);
> +	if (ret)
> +		return ret;
> +
> +	ret = usb4_switch_op(sw, USB4_SWITCH_OP_NVM_READ, &status);
> +	if (ret)
> +		return ret;
> +
> +	if (status)
> +		return -EIO;
> +
> +	return usb4_switch_op_read_data(sw, buf, dwords);
> +}
> +
> +/**
> + * usb4_switch_nvm_read() - Read arbitrary bytes from router NVM
> + * @sw: USB4 router
> + * @address: Starting address in bytes
> + * @buf: Read data is placed here
> + * @size: How many bytes to read
> + *
> + * Reads NVM contents of the router. If NVM is not supported returns
> + * %-EOPNOTSUPP.
> + */
> +int usb4_switch_nvm_read(struct tb_switch *sw, unsigned int address, void *buf,
> +			 size_t size)
> +{
> +	return usb4_switch_do_read_data(sw, address, buf, size,
> +					usb4_switch_nvm_read_block);
> +}
> +
> +static int usb4_switch_nvm_set_offset(struct tb_switch *sw,
> +				      unsigned int address)
> +{
> +	u32 metadata, dwaddress;
> +	u8 status = 0;
> +	int ret;
> +
> +	dwaddress = address / 4;
> +	metadata = (dwaddress << USB4_NVM_SET_OFFSET_SHIFT) &
> +		   USB4_NVM_SET_OFFSET_MASK;
> +
> +	ret = usb4_switch_op_write_metadata(sw, metadata);
> +	if (ret)
> +		return ret;
> +
> +	ret = usb4_switch_op(sw, USB4_SWITCH_OP_NVM_SET_OFFSET, &status);
> +	if (ret)
> +		return ret;
> +
> +	return status ? -EIO : 0;
> +}
> +
> +static int usb4_switch_nvm_write_next_block(struct tb_switch *sw,
> +					    const void *buf, size_t dwords)
> +{
> +	u8 status;
> +	int ret;
> +
> +	ret = usb4_switch_op_write_data(sw, buf, dwords);
> +	if (ret)
> +		return ret;
> +
> +	ret = usb4_switch_op(sw, USB4_SWITCH_OP_NVM_WRITE, &status);
> +	if (ret)
> +		return ret;
> +
> +	return status ? -EIO : 0;
> +}
> +
> +/**
> + * usb4_switch_nvm_write() - Write to the router NVM
> + * @sw: USB4 router
> + * @address: Start address where to write in bytes
> + * @buf: Pointer to the data to write
> + * @size: Size of @buf in bytes
> + *
> + * Writes @buf to the router NVM using USB4 router operations. If NVM
> + * write is not supported returns %-EOPNOTSUPP.
> + */
> +int usb4_switch_nvm_write(struct tb_switch *sw, unsigned int address,
> +			  const void *buf, size_t size)
> +{
> +	int ret;
> +
> +	ret = usb4_switch_nvm_set_offset(sw, address);
> +	if (ret)
> +		return ret;
> +
> +	return usb4_switch_do_write_data(sw, address, buf, size,
> +					 usb4_switch_nvm_write_next_block);
> +}
> +
> +/**
> + * usb4_switch_nvm_authenticate() - Authenticate new NVM
> + * @sw: USB4 router
> + *
> + * After the new NVM has been written via usb4_switch_nvm_write(), this
> + * function triggers NVM authentication process. If the authentication
> + * is successful the router is power cycled and the new NVM starts
> + * running. In case of failure returns negative errno.
> + */
> +int usb4_switch_nvm_authenticate(struct tb_switch *sw)
> +{
> +	u8 status = 0;
> +	int ret;
> +
> +	ret = usb4_switch_op(sw, USB4_SWITCH_OP_NVM_AUTH, &status);
> +	if (ret)
> +		return ret;
> +
> +	switch (status) {
> +	case 0x0:
> +		tb_sw_dbg(sw, "NVM authentication successful\n");
> +		return 0;
> +	case 0x1:
> +		return -EINVAL;
> +	case 0x2:
> +		return -EAGAIN;
> +	case 0x3:
> +		return -EOPNOTSUPP;
> +	default:
> +		return -EIO;
> +	}
> +}
> +
> +/**
> + * usb4_switch_query_dp_resource() - Query availability of DP IN resource
> + * @sw: USB4 router
> + * @in: DP IN adapter
> + *
> + * For DP tunneling this function can be used to query availability of
> + * DP IN resource. Returns true if the resource is available for DP
> + * tunneling, false otherwise.
> + */
> +bool usb4_switch_query_dp_resource(struct tb_switch *sw, struct tb_port *in)
> +{
> +	u8 status;
> +	int ret;
> +
> +	ret = usb4_switch_op_write_metadata(sw, in->port);
> +	if (ret)
> +		return false;
> +
> +	ret = usb4_switch_op(sw, USB4_SWITCH_OP_QUERY_DP_RESOURCE, &status);
> +	/*
> +	 * If DP resource allocation is not supported assume it is
> +	 * always available.
> +	 */
> +	if (ret == -EOPNOTSUPP)
> +		return true;
> +	else if (ret)
> +		return false;
> +
> +	return !status;
> +}
> +
> +/**
> + * usb4_switch_alloc_dp_resource() - Allocate DP IN resource
> + * @sw: USB4 router
> + * @in: DP IN adapter
> + *
> + * Allocates DP IN resource for DP tunneling using USB4 router
> + * operations. If the resource was allocated returns %0. Otherwise
> + * returns negative errno, in particular %-EBUSY if the resource is
> + * already allocated.
> + */
> +int usb4_switch_alloc_dp_resource(struct tb_switch *sw, struct tb_port *in)
> +{
> +	u8 status;
> +	int ret;
> +
> +	ret = usb4_switch_op_write_metadata(sw, in->port);
> +	if (ret)
> +		return ret;
> +
> +	ret = usb4_switch_op(sw, USB4_SWITCH_OP_ALLOC_DP_RESOURCE, &status);
> +	if (ret == -EOPNOTSUPP)
> +		return 0;
> +	else if (ret)
> +		return ret;
> +
> +	return status ? -EBUSY : 0;
> +}
> +
> +/**
> + * usb4_switch_dealloc_dp_resource() - Releases allocated DP IN resource
> + * @sw: USB4 router
> + * @in: DP IN adapter
> + *
> + * Releases the previously allocated DP IN resource.
> + */
> +int usb4_switch_dealloc_dp_resource(struct tb_switch *sw, struct tb_port *in)
> +{
> +	u8 status;
> +	int ret;
> +
> +	ret = usb4_switch_op_write_metadata(sw, in->port);
> +	if (ret)
> +		return ret;
> +
> +	ret = usb4_switch_op(sw, USB4_SWITCH_OP_DEALLOC_DP_RESOURCE, &status);
> +	if (ret == -EOPNOTSUPP)
> +		return 0;
> +	else if (ret)
> +		return ret;
> +
> +	return status ? -EIO : 0;
> +}
> +
> +static int usb4_port_idx(const struct tb_switch *sw, const struct tb_port *port)
> +{
> +	struct tb_port *p;
> +	int usb4_idx = 0;
> +
> +	/* Assume port is primary */
> +	tb_switch_for_each_port(sw, p) {
> +		if (!tb_port_is_null(p))
> +			continue;
> +		if (tb_is_upstream_port(p))
> +			continue;
> +		if (!p->link_nr) {
> +			if (p == port)
> +				break;
> +			usb4_idx++;
> +		}
> +	}
> +
> +	return usb4_idx;
> +}
> +
> +/**
> + * usb4_switch_map_pcie_down() - Map USB4 port to a PCIe downstream adapter
> + * @sw: USB4 router
> + * @port: USB4 port
> + *
> + * USB4 routers have direct mapping between USB4 ports and PCIe
> + * downstream adapters where the PCIe topology is extended. This
> + * function returns the corresponding downstream PCIe adapter or %NULL
> + * if no such mapping was possible.
> + */
> +struct tb_port *usb4_switch_map_pcie_down(struct tb_switch *sw,
> +					  const struct tb_port *port)
> +{
> +	int usb4_idx = usb4_port_idx(sw, port);
> +	struct tb_port *p;
> +	int pcie_idx = 0;
> +
> +	/* Find PCIe down port matching usb4_port */
> +	tb_switch_for_each_port(sw, p) {
> +		if (!tb_port_is_pcie_down(p))
> +			continue;
> +
> +		if (pcie_idx == usb4_idx && !tb_pci_port_is_enabled(p))
> +			return p;
> +
> +		pcie_idx++;
> +	}
> +
> +	return NULL;
> +}
> +
> +/**
> + * usb4_port_unlock() - Unlock USB4 downstream port
> + * @port: USB4 port to unlock
> + *
> + * Unlocks USB4 downstream port so that the connection manager can
> + * access the router below this port.
> + */
> +int usb4_port_unlock(struct tb_port *port)
> +{
> +	int ret;
> +	u32 val;
> +
> +	ret = tb_port_read(port, &val, TB_CFG_PORT, ADP_CS_4, 1);
> +	if (ret)
> +		return ret;
> +
> +	val &= ~ADP_CS_4_LCK;
> +	return tb_port_write(port, &val, TB_CFG_PORT, ADP_CS_4, 1);
> +}
> diff --git a/drivers/thunderbolt/xdomain.c b/drivers/thunderbolt/xdomain.c
> index 880d784398a3..053f918e00e8 100644
> --- a/drivers/thunderbolt/xdomain.c
> +++ b/drivers/thunderbolt/xdomain.c
> @@ -1220,7 +1220,13 @@ struct tb_xdomain *tb_xdomain_alloc(struct tb *tb, struct device *parent,
>  				    u64 route, const uuid_t *local_uuid,
>  				    const uuid_t *remote_uuid)
>  {
> +	struct tb_switch *parent_sw = tb_to_switch(parent);
>  	struct tb_xdomain *xd;
> +	struct tb_port *down;
> +
> +	/* Make sure the downstream domain is accessible */
> +	down = tb_port_at(route, parent_sw);
> +	tb_port_unlock(down);
>  
>  	xd = kzalloc(sizeof(*xd), GFP_KERNEL);
>  	if (!xd)
> -- 
> 2.24.0
> 

Kind regards,
Nicholas

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