Merge tag 'net-next-6.3' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-nextgrafted

Pull networking updates from Jakub Kicinski:
 "Core:

   - Add dedicated kmem_cache for typical/small skb->head, avoid having
     to access struct page at kfree time, and improve memory use.

   - Introduce sysctl to set default RPS configuration for new netdevs.

   - Define Netlink protocol specification format which can be used to
     describe messages used by each family and auto-generate parsers.
     Add tools for generating kernel data structures and uAPI headers.

   - Expose all net/core sysctls inside netns.

   - Remove 4s sleep in netpoll if carrier is instantly detected on
     boot.

   - Add configurable limit of MDB entries per port, and port-vlan.

   - Continue populating drop reasons throughout the stack.

   - Retire a handful of legacy Qdiscs and classifiers.

  Protocols:

   - Support IPv4 big TCP (TSO frames larger than 64kB).

   - Add IP_LOCAL_PORT_RANGE socket option, to control local port range
     on socket by socket basis.

   - Track and report in procfs number of MPTCP sockets used.

   - Support mixing IPv4 and IPv6 flows in the in-kernel MPTCP path
     manager.

   - IPv6: don't check net.ipv6.route.max_size and rely on garbage
     collection to free memory (similarly to IPv4).

   - Support Penultimate Segment Pop (PSP) flavor in SRv6 (RFC8986).

   - ICMP: add per-rate limit counters.

   - Add support for user scanning requests in ieee802154.

   - Remove static WEP support.

   - Support minimal Wi-Fi 7 Extremely High Throughput (EHT) rate
     reporting.

   - WiFi 7 EHT channel puncturing support (client & AP).

  BPF:

   - Add a rbtree data structure following the "next-gen data structure"
     precedent set by recently added linked list, that is, by using
     kfunc + kptr instead of adding a new BPF map type.

   - Expose XDP hints via kfuncs with initial support for RX hash and
     timestamp metadata.

   - Add BPF_F_NO_TUNNEL_KEY extension to bpf_skb_set_tunnel_key to
     better support decap on GRE tunnel devices not operating in collect
     metadata.

   - Improve x86 JIT's codegen for PROBE_MEM runtime error checks.

   - Remove the need for trace_printk_lock for bpf_trace_printk and
     bpf_trace_vprintk helpers.

   - Extend libbpf's bpf_tracing.h support for tracing arguments of
     kprobes/uprobes and syscall as a special case.

   - Significantly reduce the search time for module symbols by
     livepatch and BPF.

   - Enable cpumasks to be used as kptrs, which is useful for tracing
     programs tracking which tasks end up running on which CPUs in
     different time intervals.

   - Add support for BPF trampoline on s390x and riscv64.

   - Add capability to export the XDP features supported by the NIC.

   - Add __bpf_kfunc tag for marking kernel functions as kfuncs.

   - Add cgroup.memory=nobpf kernel parameter option to disable BPF
     memory accounting for container environments.

  Netfilter:

   - Remove the CLUSTERIP target. It has been marked as obsolete for
     years, and we still have WARN splats wrt races of the out-of-band
     /proc interface installed by this target.

   - Add 'destroy' commands to nf_tables. They are identical to the
     existing 'delete' commands, but do not return an error if the
     referenced object (set, chain, rule...) did not exist.

  Driver API:

   - Improve cpumask_local_spread() locality to help NICs set the right
     IRQ affinity on AMD platforms.

   - Separate C22 and C45 MDIO bus transactions more clearly.

   - Introduce new DCB table to control DSCP rewrite on egress.

   - Support configuration of Physical Layer Collision Avoidance (PLCA)
     Reconciliation Sublayer (RS) (802.3cg-2019). Modern version of
     shared medium Ethernet.

   - Support for MAC Merge layer (IEEE 802.3-2018 clause 99). Allowing
     preemption of low priority frames by high priority frames.

   - Add support for controlling MACSec offload using netlink SET.

   - Rework devlink instance refcounts to allow registration and
     de-registration under the instance lock. Split the code into
     multiple files, drop some of the unnecessarily granular locks and
     factor out common parts of netlink operation handling.

   - Add TX frame aggregation parameters (for USB drivers).

   - Add a new attr TCA_EXT_WARN_MSG to report TC (offload) warning
     messages with notifications for debug.

   - Allow offloading of UDP NEW connections via act_ct.

   - Add support for per action HW stats in TC.

   - Support hardware miss to TC action (continue processing in SW from
     a specific point in the action chain).

   - Warn if old Wireless Extension user space interface is used with
     modern cfg80211/mac80211 drivers. Do not support Wireless
     Extensions for Wi-Fi 7 devices at all. Everyone should switch to
     using nl80211 interface instead.

   - Improve the CAN bit timing configuration. Use extack to return
     error messages directly to user space, update the SJW handling,
     including the definition of a new default value that will benefit
     CAN-FD controllers, by increasing their oscillator tolerance.

  New hardware / drivers:

   - Ethernet:
      - nVidia BlueField-3 support (control traffic driver)
      - Ethernet support for imx93 SoCs
      - Motorcomm yt8531 gigabit Ethernet PHY
      - onsemi NCN26000 10BASE-T1S PHY (with support for PLCA)
      - Microchip LAN8841 PHY (incl. cable diagnostics and PTP)
      - Amlogic gxl MDIO mux

   - WiFi:
      - RealTek RTL8188EU (rtl8xxxu)
      - Qualcomm Wi-Fi 7 devices (ath12k)

   - CAN:
      - Renesas R-Car V4H

  Drivers:

   - Bluetooth:
      - Set Per Platform Antenna Gain (PPAG) for Intel controllers.

   - Ethernet NICs:
      - Intel (1G, igc):
         - support TSN / Qbv / packet scheduling features of i226 model
      - Intel (100G, ice):
         - use GNSS subsystem instead of TTY
         - multi-buffer XDP support
         - extend support for GPIO pins to E823 devices
      - nVidia/Mellanox:
         - update the shared buffer configuration on PFC commands
         - implement PTP adjphase function for HW offset control
         - TC support for Geneve and GRE with VF tunnel offload
         - more efficient crypto key management method
         - multi-port eswitch support
      - Netronome/Corigine:
         - add DCB IEEE support
         - support IPsec offloading for NFP3800
      - Freescale/NXP (enetc):
         - support XDP_REDIRECT for XDP non-linear buffers
         - improve reconfig, avoid link flap and waiting for idle
         - support MAC Merge layer
      - Other NICs:
         - sfc/ef100: add basic devlink support for ef100
         - ionic: rx_push mode operation (writing descriptors via MMIO)
         - bnxt: use the auxiliary bus abstraction for RDMA
         - r8169: disable ASPM and reset bus in case of tx timeout
         - cpsw: support QSGMII mode for J721e CPSW9G
         - cpts: support pulse-per-second output
         - ngbe: add an mdio bus driver
         - usbnet: optimize usbnet_bh() by avoiding unnecessary queuing
         - r8152: handle devices with FW with NCM support
         - amd-xgbe: support 10Mbps, 2.5GbE speeds and rx-adaptation
         - virtio-net: support multi buffer XDP
         - virtio/vsock: replace virtio_vsock_pkt with sk_buff
         - tsnep: XDP support

   - Ethernet high-speed switches:
      - nVidia/Mellanox (mlxsw):
         - add support for latency TLV (in FW control messages)
      - Microchip (sparx5):
         - separate explicit and implicit traffic forwarding rules, make
           the implicit rules always active
         - add support for egress DSCP rewrite
         - IS0 VCAP support (Ingress Classification)
         - IS2 VCAP filters (protos, L3 addrs, L4 ports, flags, ToS
           etc.)
         - ES2 VCAP support (Egress Access Control)
         - support for Per-Stream Filtering and Policing (802.1Q,
           8.6.5.1)

   - Ethernet embedded switches:
      - Marvell (mv88e6xxx):
         - add MAB (port auth) offload support
         - enable PTP receive for mv88e6390
      - NXP (ocelot):
         - support MAC Merge layer
         - support for the the vsc7512 internal copper phys
      - Microchip:
         - lan9303: convert to PHYLINK
         - lan966x: support TC flower filter statistics
         - lan937x: PTP support for KSZ9563/KSZ8563 and LAN937x
         - lan937x: support Credit Based Shaper configuration
         - ksz9477: support Energy Efficient Ethernet
      - other:
         - qca8k: convert to regmap read/write API, use bulk operations
         - rswitch: Improve TX timestamp accuracy

   - Intel WiFi (iwlwifi):
      - EHT (Wi-Fi 7) rate reporting
      - STEP equalizer support: transfer some STEP (connection to radio
        on platforms with integrated wifi) related parameters from the
        BIOS to the firmware.

   - Qualcomm 802.11ax WiFi (ath11k):
      - IPQ5018 support
      - Fine Timing Measurement (FTM) responder role support
      - channel 177 support

   - MediaTek WiFi (mt76):
      - per-PHY LED support
      - mt7996: EHT (Wi-Fi 7) support
      - Wireless Ethernet Dispatch (WED) reset support
      - switch to using page pool allocator

   - RealTek WiFi (rtw89):
      - support new version of Bluetooth co-existance

   - Mobile:
      - rmnet: support TX aggregation"

* tag 'net-next-6.3' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next: (1872 commits)
  page_pool: add a comment explaining the fragment counter usage
  net: ethtool: fix __ethtool_dev_mm_supported() implementation
  ethtool: pse-pd: Fix double word in comments
  xsk: add linux/vmalloc.h to xsk.c
  sefltests: netdevsim: wait for devlink instance after netns removal
  selftest: fib_tests: Always cleanup before exit
  net/mlx5e: Align IPsec ASO result memory to be as required by hardware
  net/mlx5e: TC, Set CT miss to the specific ct action instance
  net/mlx5e: Rename CHAIN_TO_REG to MAPPED_OBJ_TO_REG
  net/mlx5: Refactor tc miss handling to a single function
  net/mlx5: Kconfig: Make tc offload depend on tc skb extension
  net/sched: flower: Support hardware miss to tc action
  net/sched: flower: Move filter handle initialization earlier
  net/sched: cls_api: Support hardware miss to tc action
  net/sched: Rename user cookie and act cookie
  sfc: fix builds without CONFIG_RTC_LIB
  sfc: clean up some inconsistent indentings
  net/mlx4_en: Introduce flexible array to silence overflow warning
  net: lan966x: Fix possible deadlock inside PTP
  net/ulp: Remove redundant ->clone() test in inet_clone_ulp().
  ...

1 files changed, 582 insertions, 0 deletions

diff --git a/drivers/usb/host/xhci-dbgtty.c b/drivers/usb/host/xhci-dbgtty.c
new file mode 100644
index 000000000..d3acc0829
--- /dev/null
+++ b/drivers/usb/host/xhci-dbgtty.c
@@ -0,0 +1,582 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * xhci-dbgtty.c - tty glue for xHCI debug capability
+ *
+ * Copyright (C) 2017 Intel Corporation
+ *
+ * Author: Lu Baolu <baolu.lu@linux.intel.com>
+ */
+
+#include <linux/slab.h>
+#include <linux/tty.h>
+#include <linux/tty_flip.h>
+#include <linux/idr.h>
+
+#include "xhci.h"
+#include "xhci-dbgcap.h"
+
+static struct tty_driver *dbc_tty_driver;
+static struct idr dbc_tty_minors;
+static DEFINE_MUTEX(dbc_tty_minors_lock);
+
+static inline struct dbc_port *dbc_to_port(struct xhci_dbc *dbc)
+{
+	return dbc->priv;
+}
+
+static unsigned int
+dbc_send_packet(struct dbc_port *port, char *packet, unsigned int size)
+{
+	unsigned int		len;
+
+	len = kfifo_len(&port->write_fifo);
+	if (len < size)
+		size = len;
+	if (size != 0)
+		size = kfifo_out(&port->write_fifo, packet, size);
+	return size;
+}
+
+static int dbc_start_tx(struct dbc_port *port)
+	__releases(&port->port_lock)
+	__acquires(&port->port_lock)
+{
+	int			len;
+	struct dbc_request	*req;
+	int			status = 0;
+	bool			do_tty_wake = false;
+	struct list_head	*pool = &port->write_pool;
+
+	while (!list_empty(pool)) {
+		req = list_entry(pool->next, struct dbc_request, list_pool);
+		len = dbc_send_packet(port, req->buf, DBC_MAX_PACKET);
+		if (len == 0)
+			break;
+		do_tty_wake = true;
+
+		req->length = len;
+		list_del(&req->list_pool);
+
+		spin_unlock(&port->port_lock);
+		status = dbc_ep_queue(req);
+		spin_lock(&port->port_lock);
+
+		if (status) {
+			list_add(&req->list_pool, pool);
+			break;
+		}
+	}
+
+	if (do_tty_wake && port->port.tty)
+		tty_wakeup(port->port.tty);
+
+	return status;
+}
+
+static void dbc_start_rx(struct dbc_port *port)
+	__releases(&port->port_lock)
+	__acquires(&port->port_lock)
+{
+	struct dbc_request	*req;
+	int			status;
+	struct list_head	*pool = &port->read_pool;
+
+	while (!list_empty(pool)) {
+		if (!port->port.tty)
+			break;
+
+		req = list_entry(pool->next, struct dbc_request, list_pool);
+		list_del(&req->list_pool);
+		req->length = DBC_MAX_PACKET;
+
+		spin_unlock(&port->port_lock);
+		status = dbc_ep_queue(req);
+		spin_lock(&port->port_lock);
+
+		if (status) {
+			list_add(&req->list_pool, pool);
+			break;
+		}
+	}
+}
+
+static void
+dbc_read_complete(struct xhci_dbc *dbc, struct dbc_request *req)
+{
+	unsigned long		flags;
+	struct dbc_port		*port = dbc_to_port(dbc);
+
+	spin_lock_irqsave(&port->port_lock, flags);
+	list_add_tail(&req->list_pool, &port->read_queue);
+	tasklet_schedule(&port->push);
+	spin_unlock_irqrestore(&port->port_lock, flags);
+}
+
+static void dbc_write_complete(struct xhci_dbc *dbc, struct dbc_request *req)
+{
+	unsigned long		flags;
+	struct dbc_port		*port = dbc_to_port(dbc);
+
+	spin_lock_irqsave(&port->port_lock, flags);
+	list_add(&req->list_pool, &port->write_pool);
+	switch (req->status) {
+	case 0:
+		dbc_start_tx(port);
+		break;
+	case -ESHUTDOWN:
+		break;
+	default:
+		dev_warn(dbc->dev, "unexpected write complete status %d\n",
+			  req->status);
+		break;
+	}
+	spin_unlock_irqrestore(&port->port_lock, flags);
+}
+
+static void xhci_dbc_free_req(struct dbc_request *req)
+{
+	kfree(req->buf);
+	dbc_free_request(req);
+}
+
+static int
+xhci_dbc_alloc_requests(struct xhci_dbc *dbc, unsigned int direction,
+			struct list_head *head,
+			void (*fn)(struct xhci_dbc *, struct dbc_request *))
+{
+	int			i;
+	struct dbc_request	*req;
+
+	for (i = 0; i < DBC_QUEUE_SIZE; i++) {
+		req = dbc_alloc_request(dbc, direction, GFP_KERNEL);
+		if (!req)
+			break;
+
+		req->length = DBC_MAX_PACKET;
+		req->buf = kmalloc(req->length, GFP_KERNEL);
+		if (!req->buf) {
+			dbc_free_request(req);
+			break;
+		}
+
+		req->complete = fn;
+		list_add_tail(&req->list_pool, head);
+	}
+
+	return list_empty(head) ? -ENOMEM : 0;
+}
+
+static void
+xhci_dbc_free_requests(struct list_head *head)
+{
+	struct dbc_request	*req;
+
+	while (!list_empty(head)) {
+		req = list_entry(head->next, struct dbc_request, list_pool);
+		list_del(&req->list_pool);
+		xhci_dbc_free_req(req);
+	}
+}
+
+static int dbc_tty_install(struct tty_driver *driver, struct tty_struct *tty)
+{
+	struct dbc_port		*port;
+
+	mutex_lock(&dbc_tty_minors_lock);
+	port = idr_find(&dbc_tty_minors, tty->index);
+	mutex_unlock(&dbc_tty_minors_lock);
+
+	if (!port)
+		return -ENXIO;
+
+	tty->driver_data = port;
+
+	return tty_port_install(&port->port, driver, tty);
+}
+
+static int dbc_tty_open(struct tty_struct *tty, struct file *file)
+{
+	struct dbc_port		*port = tty->driver_data;
+
+	return tty_port_open(&port->port, tty, file);
+}
+
+static void dbc_tty_close(struct tty_struct *tty, struct file *file)
+{
+	struct dbc_port		*port = tty->driver_data;
+
+	tty_port_close(&port->port, tty, file);
+}
+
+static int dbc_tty_write(struct tty_struct *tty,
+			 const unsigned char *buf,
+			 int count)
+{
+	struct dbc_port		*port = tty->driver_data;
+	unsigned long		flags;
+
+	spin_lock_irqsave(&port->port_lock, flags);
+	if (count)
+		count = kfifo_in(&port->write_fifo, buf, count);
+	dbc_start_tx(port);
+	spin_unlock_irqrestore(&port->port_lock, flags);
+
+	return count;
+}
+
+static int dbc_tty_put_char(struct tty_struct *tty, unsigned char ch)
+{
+	struct dbc_port		*port = tty->driver_data;
+	unsigned long		flags;
+	int			status;
+
+	spin_lock_irqsave(&port->port_lock, flags);
+	status = kfifo_put(&port->write_fifo, ch);
+	spin_unlock_irqrestore(&port->port_lock, flags);
+
+	return status;
+}
+
+static void dbc_tty_flush_chars(struct tty_struct *tty)
+{
+	struct dbc_port		*port = tty->driver_data;
+	unsigned long		flags;
+
+	spin_lock_irqsave(&port->port_lock, flags);
+	dbc_start_tx(port);
+	spin_unlock_irqrestore(&port->port_lock, flags);
+}
+
+static unsigned int dbc_tty_write_room(struct tty_struct *tty)
+{
+	struct dbc_port		*port = tty->driver_data;
+	unsigned long		flags;
+	unsigned int		room;
+
+	spin_lock_irqsave(&port->port_lock, flags);
+	room = kfifo_avail(&port->write_fifo);
+	spin_unlock_irqrestore(&port->port_lock, flags);
+
+	return room;
+}
+
+static unsigned int dbc_tty_chars_in_buffer(struct tty_struct *tty)
+{
+	struct dbc_port		*port = tty->driver_data;
+	unsigned long		flags;
+	unsigned int		chars;
+
+	spin_lock_irqsave(&port->port_lock, flags);
+	chars = kfifo_len(&port->write_fifo);
+	spin_unlock_irqrestore(&port->port_lock, flags);
+
+	return chars;
+}
+
+static void dbc_tty_unthrottle(struct tty_struct *tty)
+{
+	struct dbc_port		*port = tty->driver_data;
+	unsigned long		flags;
+
+	spin_lock_irqsave(&port->port_lock, flags);
+	tasklet_schedule(&port->push);
+	spin_unlock_irqrestore(&port->port_lock, flags);
+}
+
+static const struct tty_operations dbc_tty_ops = {
+	.install		= dbc_tty_install,
+	.open			= dbc_tty_open,
+	.close			= dbc_tty_close,
+	.write			= dbc_tty_write,
+	.put_char		= dbc_tty_put_char,
+	.flush_chars		= dbc_tty_flush_chars,
+	.write_room		= dbc_tty_write_room,
+	.chars_in_buffer	= dbc_tty_chars_in_buffer,
+	.unthrottle		= dbc_tty_unthrottle,
+};
+
+static void dbc_rx_push(struct tasklet_struct *t)
+{
+	struct dbc_request	*req;
+	struct tty_struct	*tty;
+	unsigned long		flags;
+	bool			do_push = false;
+	bool			disconnect = false;
+	struct dbc_port		*port = from_tasklet(port, t, push);
+	struct list_head	*queue = &port->read_queue;
+
+	spin_lock_irqsave(&port->port_lock, flags);
+	tty = port->port.tty;
+	while (!list_empty(queue)) {
+		req = list_first_entry(queue, struct dbc_request, list_pool);
+
+		if (tty && tty_throttled(tty))
+			break;
+
+		switch (req->status) {
+		case 0:
+			break;
+		case -ESHUTDOWN:
+			disconnect = true;
+			break;
+		default:
+			pr_warn("ttyDBC0: unexpected RX status %d\n",
+				req->status);
+			break;
+		}
+
+		if (req->actual) {
+			char		*packet = req->buf;
+			unsigned int	n, size = req->actual;
+			int		count;
+
+			n = port->n_read;
+			if (n) {
+				packet += n;
+				size -= n;
+			}
+
+			count = tty_insert_flip_string(&port->port, packet,
+						       size);
+			if (count)
+				do_push = true;
+			if (count != size) {
+				port->n_read += count;
+				break;
+			}
+			port->n_read = 0;
+		}
+
+		list_move(&req->list_pool, &port->read_pool);
+	}
+
+	if (do_push)
+		tty_flip_buffer_push(&port->port);
+
+	if (!list_empty(queue) && tty) {
+		if (!tty_throttled(tty)) {
+			if (do_push)
+				tasklet_schedule(&port->push);
+			else
+				pr_warn("ttyDBC0: RX not scheduled?\n");
+		}
+	}
+
+	if (!disconnect)
+		dbc_start_rx(port);
+
+	spin_unlock_irqrestore(&port->port_lock, flags);
+}
+
+static int dbc_port_activate(struct tty_port *_port, struct tty_struct *tty)
+{
+	unsigned long	flags;
+	struct dbc_port	*port = container_of(_port, struct dbc_port, port);
+
+	spin_lock_irqsave(&port->port_lock, flags);
+	dbc_start_rx(port);
+	spin_unlock_irqrestore(&port->port_lock, flags);
+
+	return 0;
+}
+
+static const struct tty_port_operations dbc_port_ops = {
+	.activate =	dbc_port_activate,
+};
+
+static void
+xhci_dbc_tty_init_port(struct xhci_dbc *dbc, struct dbc_port *port)
+{
+	tty_port_init(&port->port);
+	spin_lock_init(&port->port_lock);
+	tasklet_setup(&port->push, dbc_rx_push);
+	INIT_LIST_HEAD(&port->read_pool);
+	INIT_LIST_HEAD(&port->read_queue);
+	INIT_LIST_HEAD(&port->write_pool);
+
+	port->port.ops =	&dbc_port_ops;
+	port->n_read =		0;
+}
+
+static void
+xhci_dbc_tty_exit_port(struct dbc_port *port)
+{
+	tasklet_kill(&port->push);
+	tty_port_destroy(&port->port);
+}
+
+static int xhci_dbc_tty_register_device(struct xhci_dbc *dbc)
+{
+	int			ret;
+	struct device		*tty_dev;
+	struct dbc_port		*port = dbc_to_port(dbc);
+
+	if (port->registered)
+		return -EBUSY;
+
+	xhci_dbc_tty_init_port(dbc, port);
+
+	mutex_lock(&dbc_tty_minors_lock);
+	port->minor = idr_alloc(&dbc_tty_minors, port, 0, 64, GFP_KERNEL);
+	mutex_unlock(&dbc_tty_minors_lock);
+
+	if (port->minor < 0) {
+		ret = port->minor;
+		goto err_idr;
+	}
+
+	ret = kfifo_alloc(&port->write_fifo, DBC_WRITE_BUF_SIZE, GFP_KERNEL);
+	if (ret)
+		goto err_exit_port;
+
+	ret = xhci_dbc_alloc_requests(dbc, BULK_IN, &port->read_pool,
+				      dbc_read_complete);
+	if (ret)
+		goto err_free_fifo;
+
+	ret = xhci_dbc_alloc_requests(dbc, BULK_OUT, &port->write_pool,
+				      dbc_write_complete);
+	if (ret)
+		goto err_free_requests;
+
+	tty_dev = tty_port_register_device(&port->port,
+					   dbc_tty_driver, port->minor, NULL);
+	if (IS_ERR(tty_dev)) {
+		ret = PTR_ERR(tty_dev);
+		goto err_free_requests;
+	}
+
+	port->registered = true;
+
+	return 0;
+
+err_free_requests:
+	xhci_dbc_free_requests(&port->read_pool);
+	xhci_dbc_free_requests(&port->write_pool);
+err_free_fifo:
+	kfifo_free(&port->write_fifo);
+err_exit_port:
+	idr_remove(&dbc_tty_minors, port->minor);
+err_idr:
+	xhci_dbc_tty_exit_port(port);
+
+	dev_err(dbc->dev, "can't register tty port, err %d\n", ret);
+
+	return ret;
+}
+
+static void xhci_dbc_tty_unregister_device(struct xhci_dbc *dbc)
+{
+	struct dbc_port		*port = dbc_to_port(dbc);
+
+	if (!port->registered)
+		return;
+	tty_unregister_device(dbc_tty_driver, port->minor);
+	xhci_dbc_tty_exit_port(port);
+	port->registered = false;
+
+	mutex_lock(&dbc_tty_minors_lock);
+	idr_remove(&dbc_tty_minors, port->minor);
+	mutex_unlock(&dbc_tty_minors_lock);
+
+	kfifo_free(&port->write_fifo);
+	xhci_dbc_free_requests(&port->read_pool);
+	xhci_dbc_free_requests(&port->read_queue);
+	xhci_dbc_free_requests(&port->write_pool);
+}
+
+static const struct dbc_driver dbc_driver = {
+	.configure		= xhci_dbc_tty_register_device,
+	.disconnect		= xhci_dbc_tty_unregister_device,
+};
+
+int xhci_dbc_tty_probe(struct device *dev, void __iomem *base, struct xhci_hcd *xhci)
+{
+	struct xhci_dbc		*dbc;
+	struct dbc_port		*port;
+	int			status;
+
+	if (!dbc_tty_driver)
+		return -ENODEV;
+
+	port = kzalloc(sizeof(*port), GFP_KERNEL);
+	if (!port)
+		return -ENOMEM;
+
+	dbc = xhci_alloc_dbc(dev, base, &dbc_driver);
+
+	if (!dbc) {
+		status = -ENOMEM;
+		goto out2;
+	}
+
+	dbc->priv = port;
+
+	/* get rid of xhci once this is a real driver binding to a device */
+	xhci->dbc = dbc;
+
+	return 0;
+out2:
+	kfree(port);
+
+	return status;
+}
+
+/*
+ * undo what probe did, assume dbc is stopped already.
+ * we also assume tty_unregister_device() is called before this
+ */
+void xhci_dbc_tty_remove(struct xhci_dbc *dbc)
+{
+	struct dbc_port         *port = dbc_to_port(dbc);
+
+	xhci_dbc_remove(dbc);
+	kfree(port);
+}
+
+int dbc_tty_init(void)
+{
+	int		ret;
+
+	idr_init(&dbc_tty_minors);
+
+	dbc_tty_driver = tty_alloc_driver(64, TTY_DRIVER_REAL_RAW |
+					  TTY_DRIVER_DYNAMIC_DEV);
+	if (IS_ERR(dbc_tty_driver)) {
+		idr_destroy(&dbc_tty_minors);
+		return PTR_ERR(dbc_tty_driver);
+	}
+
+	dbc_tty_driver->driver_name = "dbc_serial";
+	dbc_tty_driver->name = "ttyDBC";
+
+	dbc_tty_driver->type = TTY_DRIVER_TYPE_SERIAL;
+	dbc_tty_driver->subtype = SERIAL_TYPE_NORMAL;
+	dbc_tty_driver->init_termios = tty_std_termios;
+	dbc_tty_driver->init_termios.c_cflag =
+			B9600 | CS8 | CREAD | HUPCL | CLOCAL;
+	dbc_tty_driver->init_termios.c_ispeed = 9600;
+	dbc_tty_driver->init_termios.c_ospeed = 9600;
+
+	tty_set_operations(dbc_tty_driver, &dbc_tty_ops);
+
+	ret = tty_register_driver(dbc_tty_driver);
+	if (ret) {
+		pr_err("Can't register dbc tty driver\n");
+		tty_driver_kref_put(dbc_tty_driver);
+		idr_destroy(&dbc_tty_minors);
+	}
+
+	return ret;
+}
+
+void dbc_tty_exit(void)
+{
+	if (dbc_tty_driver) {
+		tty_unregister_driver(dbc_tty_driver);
+		tty_driver_kref_put(dbc_tty_driver);
+		dbc_tty_driver = NULL;
+	}
+
+	idr_destroy(&dbc_tty_minors);
+}