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, 463 insertions, 0 deletions

diff --git a/drivers/usb/serial/mct_u232.h b/drivers/usb/serial/mct_u232.h
new file mode 100644
index 000000000..e3d09a83c
--- /dev/null
+++ b/drivers/usb/serial/mct_u232.h
@@ -0,0 +1,463 @@
+/* SPDX-License-Identifier: GPL-2.0+ */
+/*
+ * Definitions for MCT (Magic Control Technology) USB-RS232 Converter Driver
+ *
+ *   Copyright (C) 2000 Wolfgang Grandegger (wolfgang@ces.ch)
+ *
+ * This driver is for the device MCT USB-RS232 Converter (25 pin, Model No.
+ * U232-P25) from Magic Control Technology Corp. (there is also a 9 pin
+ * Model No. U232-P9). See http://www.mct.com.tw/products/product_us232.html 
+ * for further information. The properties of this device are listed at the end 
+ * of this file. This device was used in the Dlink DSB-S25.
+ *
+ * All of the information about the device was acquired by using SniffUSB
+ * on Windows98. The technical details of the reverse engineering are
+ * summarized at the end of this file.
+ */
+
+#ifndef __LINUX_USB_SERIAL_MCT_U232_H
+#define __LINUX_USB_SERIAL_MCT_U232_H
+
+#define MCT_U232_VID	                0x0711	/* Vendor Id */
+#define MCT_U232_PID	                0x0210	/* Original MCT Product Id */
+
+/* U232-P25, Sitecom */
+#define MCT_U232_SITECOM_PID		0x0230	/* Sitecom Product Id */
+
+/* DU-H3SP USB BAY hub */
+#define MCT_U232_DU_H3SP_PID		0x0200	/* D-Link DU-H3SP USB BAY */
+
+/* Belkin badge the MCT U232-P9 as the F5U109 */
+#define MCT_U232_BELKIN_F5U109_VID	0x050d	/* Vendor Id */
+#define MCT_U232_BELKIN_F5U109_PID	0x0109	/* Product Id */
+
+/*
+ * Vendor Request Interface
+ */
+#define MCT_U232_SET_REQUEST_TYPE	0x40
+#define MCT_U232_GET_REQUEST_TYPE	0xc0
+
+/* Get Modem Status Register (MSR) */
+#define MCT_U232_GET_MODEM_STAT_REQUEST	2
+#define MCT_U232_GET_MODEM_STAT_SIZE	1
+
+/* Get Line Control Register (LCR) */
+/* ... not used by this driver */
+#define MCT_U232_GET_LINE_CTRL_REQUEST	6
+#define MCT_U232_GET_LINE_CTRL_SIZE	1
+
+/* Set Baud Rate Divisor */
+#define MCT_U232_SET_BAUD_RATE_REQUEST	5
+#define MCT_U232_SET_BAUD_RATE_SIZE	4
+
+/* Set Line Control Register (LCR) */
+#define MCT_U232_SET_LINE_CTRL_REQUEST	7
+#define MCT_U232_SET_LINE_CTRL_SIZE	1
+
+/* Set Modem Control Register (MCR) */
+#define MCT_U232_SET_MODEM_CTRL_REQUEST	10
+#define MCT_U232_SET_MODEM_CTRL_SIZE	1
+
+/*
+ * This USB device request code is not well understood.  It is transmitted by
+ * the MCT-supplied Windows driver whenever the baud rate changes.
+ */
+#define MCT_U232_SET_UNKNOWN1_REQUEST	11  /* Unknown functionality */
+#define MCT_U232_SET_UNKNOWN1_SIZE	1
+
+/*
+ * This USB device request code appears to control whether CTS is required
+ * during transmission.
+ *
+ * Sending a zero byte allows data transmission to a device which is not
+ * asserting CTS.  Sending a '1' byte will cause transmission to be deferred
+ * until the device asserts CTS.
+ */
+#define MCT_U232_SET_CTS_REQUEST	12
+#define MCT_U232_SET_CTS_SIZE		1
+
+#define MCT_U232_MAX_SIZE		4	/* of MCT_XXX_SIZE */
+
+/*
+ * Baud rate (divisor)
+ * Actually, there are two of them, MCT website calls them "Philips solution"
+ * and "Intel solution". They are the regular MCT and "Sitecom" for us.
+ * This is pointless to document in the header, see the code for the bits.
+ */
+static int mct_u232_calculate_baud_rate(struct usb_serial *serial,
+					speed_t value, speed_t *result);
+
+/*
+ * Line Control Register (LCR)
+ */
+#define MCT_U232_SET_BREAK              0x40
+
+#define MCT_U232_PARITY_SPACE		0x38
+#define MCT_U232_PARITY_MARK		0x28
+#define MCT_U232_PARITY_EVEN		0x18
+#define MCT_U232_PARITY_ODD		0x08
+#define MCT_U232_PARITY_NONE		0x00
+
+#define MCT_U232_DATA_BITS_5            0x00
+#define MCT_U232_DATA_BITS_6            0x01
+#define MCT_U232_DATA_BITS_7            0x02
+#define MCT_U232_DATA_BITS_8            0x03
+
+#define MCT_U232_STOP_BITS_2            0x04
+#define MCT_U232_STOP_BITS_1            0x00
+
+/*
+ * Modem Control Register (MCR)
+ */
+#define MCT_U232_MCR_NONE               0x8     /* Deactivate DTR and RTS */
+#define MCT_U232_MCR_RTS                0xa     /* Activate RTS */
+#define MCT_U232_MCR_DTR                0x9     /* Activate DTR */
+
+/*
+ * Modem Status Register (MSR)
+ */
+#define MCT_U232_MSR_INDEX              0x0     /* data[index] */
+#define MCT_U232_MSR_CD                 0x80    /* Current CD */
+#define MCT_U232_MSR_RI                 0x40    /* Current RI */
+#define MCT_U232_MSR_DSR                0x20    /* Current DSR */
+#define MCT_U232_MSR_CTS                0x10    /* Current CTS */
+#define MCT_U232_MSR_DCD                0x08    /* Delta CD */
+#define MCT_U232_MSR_DRI                0x04    /* Delta RI */
+#define MCT_U232_MSR_DDSR               0x02    /* Delta DSR */
+#define MCT_U232_MSR_DCTS               0x01    /* Delta CTS */
+
+/*
+ * Line Status Register (LSR)
+ */
+#define MCT_U232_LSR_INDEX	1	/* data[index] */
+#define MCT_U232_LSR_ERR	0x80	/* OE | PE | FE | BI */
+#define MCT_U232_LSR_TEMT	0x40	/* transmit register empty */
+#define MCT_U232_LSR_THRE	0x20	/* transmit holding register empty */
+#define MCT_U232_LSR_BI		0x10	/* break indicator */
+#define MCT_U232_LSR_FE		0x08	/* framing error */
+#define MCT_U232_LSR_OE		0x02	/* overrun error */
+#define MCT_U232_LSR_PE		0x04	/* parity error */
+#define MCT_U232_LSR_OE		0x02	/* overrun error */
+#define MCT_U232_LSR_DR		0x01	/* receive data ready */
+
+
+/* -----------------------------------------------------------------------------
+ * Technical Specification reverse engineered with SniffUSB on Windows98
+ * =====================================================================
+ *
+ *  The technical details of the device have been acquired be using "SniffUSB"
+ *  and the vendor-supplied device driver (version 2.3A) under Windows98. To
+ *  identify the USB vendor-specific requests and to assign them to terminal
+ *  settings (flow control, baud rate, etc.) the program "SerialSettings" from
+ *  William G. Greathouse has been proven to be very useful. I also used the
+ *  Win98 "HyperTerminal" and "usb-robot" on Linux for testing. The results and
+ *  observations are summarized below:
+ *
+ *  The USB requests seem to be directly mapped to the registers of a 8250,
+ *  16450 or 16550 UART. The FreeBSD handbook (appendix F.4 "Input/Output
+ *  devices") contains a comprehensive description of UARTs and its registers.
+ *  The bit descriptions are actually taken from there.
+ *
+ *
+ * Baud rate (divisor)
+ * -------------------
+ *
+ *   BmRequestType:  0x40 (0100 0000B)
+ *   bRequest:       0x05
+ *   wValue:         0x0000
+ *   wIndex:         0x0000
+ *   wLength:        0x0004
+ *   Data:           divisor = 115200 / baud_rate
+ *
+ *   SniffUSB observations (Nov 2003): Contrary to the 'wLength' value of 4
+ *   shown above, observations with a Belkin F5U109 adapter, using the
+ *   MCT-supplied Windows98 driver (U2SPORT.VXD, "File version: 1.21P.0104 for
+ *   Win98/Me"), show this request has a length of 1 byte, presumably because
+ *   of the fact that the Belkin adapter and the 'Sitecom U232-P25' adapter
+ *   use a baud-rate code instead of a conventional RS-232 baud rate divisor.
+ *   The current source code for this driver does not reflect this fact, but
+ *   the driver works fine with this adapter/driver combination nonetheless.
+ *
+ *
+ * Line Control Register (LCR)
+ * ---------------------------
+ *
+ *  BmRequestType:  0x40 (0100 0000B)    0xc0 (1100 0000B)
+ *  bRequest:       0x07                 0x06
+ *  wValue:         0x0000
+ *  wIndex:         0x0000
+ *  wLength:        0x0001
+ *  Data:           LCR (see below)
+ *
+ *  Bit 7: Divisor Latch Access Bit (DLAB). When set, access to the data
+ *	   transmit/receive register (THR/RBR) and the Interrupt Enable Register
+ *	   (IER) is disabled. Any access to these ports is now redirected to the
+ *	   Divisor Latch Registers. Setting this bit, loading the Divisor
+ *	   Registers, and clearing DLAB should be done with interrupts disabled.
+ *  Bit 6: Set Break. When set to "1", the transmitter begins to transmit
+ *	   continuous Spacing until this bit is set to "0". This overrides any
+ *	   bits of characters that are being transmitted.
+ *  Bit 5: Stick Parity. When parity is enabled, setting this bit causes parity
+ *	   to always be "1" or "0", based on the value of Bit 4.
+ *  Bit 4: Even Parity Select (EPS). When parity is enabled and Bit 5 is "0",
+ *	   setting this bit causes even parity to be transmitted and expected.
+ *	   Otherwise, odd parity is used.
+ *  Bit 3: Parity Enable (PEN). When set to "1", a parity bit is inserted
+ *	   between the last bit of the data and the Stop Bit. The UART will also
+ *	   expect parity to be present in the received data.
+ *  Bit 2: Number of Stop Bits (STB). If set to "1" and using 5-bit data words,
+ *	   1.5 Stop Bits are transmitted and expected in each data word. For
+ *	   6, 7 and 8-bit data words, 2 Stop Bits are transmitted and expected.
+ *	   When this bit is set to "0", one Stop Bit is used on each data word.
+ *  Bit 1: Word Length Select Bit #1 (WLSB1)
+ *  Bit 0: Word Length Select Bit #0 (WLSB0)
+ *	   Together these bits specify the number of bits in each data word.
+ *	     1 0  Word Length
+ *	     0 0  5 Data Bits
+ *	     0 1  6 Data Bits
+ *	     1 0  7 Data Bits
+ *	     1 1  8 Data Bits
+ *
+ *  SniffUSB observations: Bit 7 seems not to be used. There seem to be two bugs
+ *  in the Win98 driver: the break does not work (bit 6 is not asserted) and the
+ *  stick parity bit is not cleared when set once. The LCR can also be read
+ *  back with USB request 6 but this has never been observed with SniffUSB.
+ *
+ *
+ * Modem Control Register (MCR)
+ * ----------------------------
+ *
+ *  BmRequestType:  0x40  (0100 0000B)
+ *  bRequest:       0x0a
+ *  wValue:         0x0000
+ *  wIndex:         0x0000
+ *  wLength:        0x0001
+ *  Data:           MCR (Bit 4..7, see below)
+ *
+ *  Bit 7: Reserved, always 0.
+ *  Bit 6: Reserved, always 0.
+ *  Bit 5: Reserved, always 0.
+ *  Bit 4: Loop-Back Enable. When set to "1", the UART transmitter and receiver
+ *	   are internally connected together to allow diagnostic operations. In
+ *	   addition, the UART modem control outputs are connected to the UART
+ *	   modem control inputs. CTS is connected to RTS, DTR is connected to
+ *	   DSR, OUT1 is connected to RI, and OUT 2 is connected to DCD.
+ *  Bit 3: OUT 2. An auxiliary output that the host processor may set high or
+ *	   low. In the IBM PC serial adapter (and most clones), OUT 2 is used
+ *	   to tri-state (disable) the interrupt signal from the
+ *	   8250/16450/16550 UART.
+ *  Bit 2: OUT 1. An auxiliary output that the host processor may set high or
+ *	   low. This output is not used on the IBM PC serial adapter.
+ *  Bit 1: Request to Send (RTS). When set to "1", the output of the UART -RTS
+ *	   line is Low (Active).
+ *  Bit 0: Data Terminal Ready (DTR). When set to "1", the output of the UART
+ *	   -DTR line is Low (Active).
+ *
+ *  SniffUSB observations: Bit 2 and 4 seem not to be used but bit 3 has been
+ *  seen _always_ set.
+ *
+ *
+ * Modem Status Register (MSR)
+ * ---------------------------
+ *
+ *  BmRequestType:  0xc0  (1100 0000B)
+ *  bRequest:       0x02
+ *  wValue:         0x0000
+ *  wIndex:         0x0000
+ *  wLength:        0x0001
+ *  Data:           MSR (see below)
+ *
+ *  Bit 7: Data Carrier Detect (CD). Reflects the state of the DCD line on the
+ *	   UART.
+ *  Bit 6: Ring Indicator (RI). Reflects the state of the RI line on the UART.
+ *  Bit 5: Data Set Ready (DSR). Reflects the state of the DSR line on the UART.
+ *  Bit 4: Clear To Send (CTS). Reflects the state of the CTS line on the UART.
+ *  Bit 3: Delta Data Carrier Detect (DDCD). Set to "1" if the -DCD line has
+ *	   changed state one more more times since the last time the MSR was
+ *	   read by the host.
+ *  Bit 2: Trailing Edge Ring Indicator (TERI). Set to "1" if the -RI line has
+ *	   had a low to high transition since the last time the MSR was read by
+ *	   the host.
+ *  Bit 1: Delta Data Set Ready (DDSR). Set to "1" if the -DSR line has changed
+ *	   state one more more times since the last time the MSR was read by the
+ *	   host.
+ *  Bit 0: Delta Clear To Send (DCTS). Set to "1" if the -CTS line has changed
+ *	   state one more times since the last time the MSR was read by the
+ *	   host.
+ *
+ *  SniffUSB observations: the MSR is also returned as first byte on the
+ *  interrupt-in endpoint 0x83 to signal changes of modem status lines. The USB
+ *  request to read MSR cannot be applied during normal device operation.
+ *
+ *
+ * Line Status Register (LSR)
+ * --------------------------
+ *
+ *  Bit 7   Error in Receiver FIFO. On the 8250/16450 UART, this bit is zero.
+ *	    This bit is set to "1" when any of the bytes in the FIFO have one
+ *	    or more of the following error conditions: PE, FE, or BI.
+ *  Bit 6   Transmitter Empty (TEMT). When set to "1", there are no words
+ *	    remaining in the transmit FIFO or the transmit shift register. The
+ *	    transmitter is completely idle.
+ *  Bit 5   Transmitter Holding Register Empty (THRE). When set to "1", the
+ *	    FIFO (or holding register) now has room for at least one additional
+ *	    word to transmit. The transmitter may still be transmitting when
+ *	    this bit is set to "1".
+ *  Bit 4   Break Interrupt (BI). The receiver has detected a Break signal.
+ *  Bit 3   Framing Error (FE). A Start Bit was detected but the Stop Bit did
+ *	    not appear at the expected time. The received word is probably
+ *	    garbled.
+ *  Bit 2   Parity Error (PE). The parity bit was incorrect for the word
+ *	    received.
+ *  Bit 1   Overrun Error (OE). A new word was received and there was no room
+ *	    in the receive buffer. The newly-arrived word in the shift register
+ *	    is discarded. On 8250/16450 UARTs, the word in the holding register
+ *	    is discarded and the newly- arrived word is put in the holding
+ *	    register.
+ *  Bit 0   Data Ready (DR). One or more words are in the receive FIFO that the
+ *	    host may read. A word must be completely received and moved from
+ *	    the shift register into the FIFO (or holding register for
+ *	    8250/16450 designs) before this bit is set.
+ *
+ *  SniffUSB observations: the LSR is returned as second byte on the
+ *  interrupt-in endpoint 0x83 to signal error conditions. Such errors have
+ *  been seen with minicom/zmodem transfers (CRC errors).
+ *
+ *
+ * Unknown #1
+ * -------------------
+ *
+ *   BmRequestType:  0x40 (0100 0000B)
+ *   bRequest:       0x0b
+ *   wValue:         0x0000
+ *   wIndex:         0x0000
+ *   wLength:        0x0001
+ *   Data:           0x00
+ *
+ *   SniffUSB observations (Nov 2003): With the MCT-supplied Windows98 driver
+ *   (U2SPORT.VXD, "File version: 1.21P.0104 for Win98/Me"), this request
+ *   occurs immediately after a "Baud rate (divisor)" message.  It was not
+ *   observed at any other time.  It is unclear what purpose this message
+ *   serves.
+ *
+ *
+ * Unknown #2
+ * -------------------
+ *
+ *   BmRequestType:  0x40 (0100 0000B)
+ *   bRequest:       0x0c
+ *   wValue:         0x0000
+ *   wIndex:         0x0000
+ *   wLength:        0x0001
+ *   Data:           0x00
+ *
+ *   SniffUSB observations (Nov 2003): With the MCT-supplied Windows98 driver
+ *   (U2SPORT.VXD, "File version: 1.21P.0104 for Win98/Me"), this request
+ *   occurs immediately after the 'Unknown #1' message (see above).  It was
+ *   not observed at any other time.  It is unclear what other purpose (if
+ *   any) this message might serve, but without it, the USB/RS-232 adapter
+ *   will not write to RS-232 devices which do not assert the 'CTS' signal.
+ *
+ *
+ * Flow control
+ * ------------
+ *
+ *  SniffUSB observations: no flow control specific requests have been realized
+ *  apart from DTR/RTS settings. Both signals are dropped for no flow control
+ *  but asserted for hardware or software flow control.
+ *
+ *
+ * Endpoint usage
+ * --------------
+ *
+ *  SniffUSB observations: the bulk-out endpoint 0x1 and interrupt-in endpoint
+ *  0x81 is used to transmit and receive characters. The second interrupt-in
+ *  endpoint 0x83 signals exceptional conditions like modem line changes and
+ *  errors. The first byte returned is the MSR and the second byte the LSR.
+ *
+ *
+ * Other observations
+ * ------------------
+ *
+ *  Queued bulk transfers like used in visor.c did not work.
+ *
+ *
+ * Properties of the USB device used (as found in /var/log/messages)
+ * -----------------------------------------------------------------
+ *
+ *  Manufacturer: MCT Corporation.
+ *  Product: USB-232 Interfact Controller
+ *  SerialNumber: U2S22050
+ *
+ *    Length              = 18
+ *    DescriptorType      = 01
+ *    USB version         = 1.00
+ *    Vendor:Product      = 0711:0210
+ *    MaxPacketSize0      = 8
+ *    NumConfigurations   = 1
+ *    Device version      = 1.02
+ *    Device Class:SubClass:Protocol = 00:00:00
+ *      Per-interface classes
+ *  Configuration:
+ *    bLength             =    9
+ *    bDescriptorType     =   02
+ *    wTotalLength        = 0027
+ *    bNumInterfaces      =   01
+ *    bConfigurationValue =   01
+ *    iConfiguration      =   00
+ *    bmAttributes        =   c0
+ *    MaxPower            =  100mA
+ *
+ *    Interface: 0
+ *    Alternate Setting:  0
+ *      bLength             =    9
+ *      bDescriptorType     =   04
+ *      bInterfaceNumber    =   00
+ *      bAlternateSetting   =   00
+ *      bNumEndpoints       =   03
+ *      bInterface Class:SubClass:Protocol =   00:00:00
+ *      iInterface          =   00
+ *      Endpoint:
+ *	  bLength             =    7
+ *	  bDescriptorType     =   05
+ *	  bEndpointAddress    =   81 (in)
+ *	  bmAttributes        =   03 (Interrupt)
+ *	  wMaxPacketSize      = 0040
+ *	  bInterval           =   02
+ *      Endpoint:
+ *	  bLength             =    7
+ *	  bDescriptorType     =   05
+ *	  bEndpointAddress    =   01 (out)
+ *	  bmAttributes        =   02 (Bulk)
+ *	  wMaxPacketSize      = 0040
+ *	  bInterval           =   00
+ *      Endpoint:
+ *	  bLength             =    7
+ *	  bDescriptorType     =   05
+ *	  bEndpointAddress    =   83 (in)
+ *	  bmAttributes        =   03 (Interrupt)
+ *	  wMaxPacketSize      = 0002
+ *	  bInterval           =   02
+ *
+ *
+ * Hardware details (added by Martin Hamilton, 2001/12/06)
+ * -----------------------------------------------------------------
+ *
+ * This info was gleaned from opening a Belkin F5U109 DB9 USB serial
+ * adaptor, which turns out to simply be a re-badged U232-P9.  We
+ * know this because there is a sticky label on the circuit board
+ * which says "U232-P9" ;-)
+ *
+ * The circuit board inside the adaptor contains a Philips PDIUSBD12
+ * USB endpoint chip and a Philips P87C52UBAA microcontroller with
+ * embedded UART.  Exhaustive documentation for these is available at:
+ *
+ *   http://www.semiconductors.philips.com/pip/p87c52ubaa
+ *   http://www.nxp.com/acrobat_download/various/PDIUSBD12_PROGRAMMING_GUIDE.pdf
+ *
+ * Thanks to Julian Highfield for the pointer to the Philips database.
+ *
+ */
+
+#endif /* __LINUX_USB_SERIAL_MCT_U232_H */
+