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().
  ...

2 files changed, 552 insertions, 0 deletions

diff --git a/drivers/staging/most/Documentation/ABI/sysfs-class-most.txt b/drivers/staging/most/Documentation/ABI/sysfs-class-most.txt
new file mode 100644
index 000000000..48aa45acc
--- /dev/null
+++ b/drivers/staging/most/Documentation/ABI/sysfs-class-most.txt
@@ -0,0 +1,315 @@
+What:		/sys/class/most/mostcore/aims
+Date:		June 2015
+KernelVersion:	4.3
+Contact:	Christian Gromm <christian.gromm@microchip.com>
+Description:
+		List of AIMs that have been loaded.
+Users:
+
+What:		/sys/class/most/mostcore/aims/<aim>/add_link
+Date:		June 2015
+KernelVersion:	4.3
+Contact:	Christian Gromm <christian.gromm@microchip.com>
+Description:
+		This is used to establish a connection of a channel and the
+		current AIM.
+Users:
+
+What:		/sys/class/most/mostcore/aims/<aim>/remove_link
+Date:		June 2015
+KernelVersion:	4.3
+Contact:	Christian Gromm <christian.gromm@microchip.com>
+Description:
+		This is used to remove a connected channel from the
+		current AIM.
+Users:
+
+What:		/sys/class/most/mostcore/devices
+Date:		June 2015
+KernelVersion:	4.3
+Contact:	Christian Gromm <christian.gromm@microchip.com>
+Description:
+		List of attached MOST interfaces.
+Users:
+
+What:		/sys/class/most/mostcore/devices/<mdev>/description
+Date:		June 2015
+KernelVersion:	4.3
+Contact:	Christian Gromm <christian.gromm@microchip.com>
+Description:
+		Provides information about the interface type and the physical
+		location of the device. Hardware attached via USB, for instance,
+		might return <usb_device 1-1.1:1.0>
+Users:
+
+What:		/sys/class/most/mostcore/devices/<mdev>/interface
+Date:		June 2015
+KernelVersion:	4.3
+Contact:	Christian Gromm <christian.gromm@microchip.com>
+Description:
+		Indicates the type of peripheral interface the current device
+		uses.
+Users:
+
+What:		/sys/class/most/mostcore/devices/<mdev>/dci
+Date:		June 2016
+KernelVersion:	4.9
+Contact:	Christian Gromm <christian.gromm@microchip.com>
+Description:
+		If the network interface controller is attached via USB, a dci
+		directory is created that allows applications to use the
+		controller's direct communication interface (DCI) to exchange
+		information.
+Users:
+
+What:		/sys/class/most/mostcore/devices/<mdev>/dci/arb_address
+Date:		June 2016
+KernelVersion:	4.9
+Contact:	Christian Gromm <christian.gromm@microchip.com>
+Description:
+		This is used to set an arbitrary DCI register address an
+		application wants to read from or write to.
+Users:
+
+What:		/sys/class/most/mostcore/devices/<mdev>/dci/arb_value
+Date:		June 2016
+KernelVersion:	4.9
+Contact:	Christian Gromm <christian.gromm@microchip.com>
+Description:
+		This is used to read from or write to the arbitrary DCI register
+		whose address is stored in arb_address.
+Users:
+
+What:		/sys/class/most/mostcore/devices/<mdev>/dci/mep_eui48_hi
+Date:		June 2016
+KernelVersion:	4.9
+Contact:	Christian Gromm <christian.gromm@microchip.com>
+Description:
+		This is used to check and configure the MAC address.
+Users:
+
+What:		/sys/class/most/mostcore/devices/<mdev>/dci/mep_eui48_lo
+Date:		June 2016
+KernelVersion:	4.9
+Contact:	Christian Gromm <christian.gromm@microchip.com>
+Description:
+		This is used to check and configure the MAC address.
+Users:
+
+What:		/sys/class/most/mostcore/devices/<mdev>/dci/mep_eui48_mi
+Date:		June 2016
+KernelVersion:	4.9
+Contact:	Christian Gromm <christian.gromm@microchip.com>
+Description:
+		This is used to check and configure the MAC address.
+Users:
+
+What:		/sys/class/most/mostcore/devices/<mdev>/dci/mep_filter
+Date:		June 2016
+KernelVersion:	4.9
+Contact:	Christian Gromm <christian.gromm@microchip.com>
+Description:
+		This is used to check and configure the MEP filter address.
+Users:
+
+What:		/sys/class/most/mostcore/devices/<mdev>/dci/mep_hash0
+Date:		June 2016
+KernelVersion:	4.9
+Contact:	Christian Gromm <christian.gromm@microchip.com>
+Description:
+		This is used to check and configure the MEP hash table.
+Users:
+
+What:		/sys/class/most/mostcore/devices/<mdev>/dci/mep_hash1
+Date:		June 2016
+KernelVersion:	4.9
+Contact:	Christian Gromm <christian.gromm@microchip.com>
+Description:
+		This is used to check and configure the MEP hash table.
+Users:
+
+What:		/sys/class/most/mostcore/devices/<mdev>/dci/mep_hash2
+Date:		June 2016
+KernelVersion:	4.9
+Contact:	Christian Gromm <christian.gromm@microchip.com>
+Description:
+		This is used to check and configure the MEP hash table.
+Users:
+
+What:		/sys/class/most/mostcore/devices/<mdev>/dci/mep_hash3
+Date:		June 2016
+KernelVersion:	4.9
+Contact:	Christian Gromm <christian.gromm@microchip.com>
+Description:
+		This is used to check and configure the MEP hash table.
+Users:
+
+What:		/sys/class/most/mostcore/devices/<mdev>/dci/ni_state
+Date:		June 2016
+KernelVersion:	4.9
+Contact:	Christian Gromm <christian.gromm@microchip.com>
+Description:
+		Indicates the current network interface state.
+Users:
+
+What:		/sys/class/most/mostcore/devices/<mdev>/dci/node_address
+Date:		June 2016
+KernelVersion:	4.9
+Contact:	Christian Gromm <christian.gromm@microchip.com>
+Description:
+		Indicates the current node address.
+Users:
+
+What:		/sys/class/most/mostcore/devices/<mdev>/dci/node_position
+Date:		June 2016
+KernelVersion:	4.9
+Contact:	Christian Gromm <christian.gromm@microchip.com>
+Description:
+		Indicates the current node position.
+Users:
+
+What:		/sys/class/most/mostcore/devices/<mdev>/dci/packet_bandwidth
+Date:		June 2016
+KernelVersion:	4.9
+Contact:	Christian Gromm <christian.gromm@microchip.com>
+Description:
+		Indicates the configured packet bandwidth.
+Users:
+
+What:		/sys/class/most/mostcore/devices/<mdev>/dci/sync_ep
+Date:		June 2016
+KernelVersion:	4.9
+Contact:	Christian Gromm <christian.gromm@microchip.com>
+Description:
+		Triggers the controller's synchronization process for a certain
+		endpoint.
+Users:
+
+What:		/sys/class/most/mostcore/devices/<mdev>/<channel>/
+Date:		June 2015
+KernelVersion:	4.3
+Contact:	Christian Gromm <christian.gromm@microchip.com>
+Description:
+		For every channel of the device a directory is created, whose
+		name is dictated by the HDM. This enables an application to
+		collect information about the channel's capabilities and
+		configure it.
+Users:
+
+What:		/sys/class/most/mostcore/devices/<mdev>/<channel>/available_datatypes
+Date:		June 2015
+KernelVersion:	4.3
+Contact:	Christian Gromm <christian.gromm@microchip.com>
+Description:
+		Indicates the data types the current channel can transport.
+Users:
+
+What:		/sys/class/most/mostcore/devices/<mdev>/<channel>/available_directions
+Date:		June 2015
+KernelVersion:	4.3
+Contact:	Christian Gromm <christian.gromm@microchip.com>
+Description:
+		Indicates the directions the current channel is capable of.
+Users:
+
+What:		/sys/class/most/mostcore/devices/<mdev>/<channel>/number_of_packet_buffers
+Date:		June 2015
+KernelVersion:	4.3
+Contact:	Christian Gromm <christian.gromm@microchip.com>
+Description:
+		Indicates the number of packet buffers the current channel can
+		handle.
+Users:
+
+What:		/sys/class/most/mostcore/devices/<mdev>/<channel>/number_of_stream_buffers
+Date:		June 2015
+KernelVersion:	4.3
+Contact:	Christian Gromm <christian.gromm@microchip.com>
+Description:
+		Indicates the number of streaming buffers the current channel can
+		handle.
+Users:
+
+What:		/sys/class/most/mostcore/devices/<mdev>/<channel>/size_of_packet_buffer
+Date:		June 2015
+KernelVersion:	4.3
+Contact:	Christian Gromm <christian.gromm@microchip.com>
+Description:
+		Indicates the size of a packet buffer the current channel can
+		handle.
+Users:
+
+What:		/sys/class/most/mostcore/devices/<mdev>/<channel>/size_of_stream_buffer
+Date:		June 2015
+KernelVersion:	4.3
+Contact:	Christian Gromm <christian.gromm@microchip.com>
+Description:
+		Indicates the size of a streaming buffer the current channel can
+		handle.
+Users:
+
+What:		/sys/class/most/mostcore/devices/<mdev>/<channel>/set_number_of_buffers
+Date:		June 2015
+KernelVersion:	4.3
+Contact:	Christian Gromm <christian.gromm@microchip.com>
+Description:
+		This is to configure the number of buffers of the current channel.
+Users:
+
+What:		/sys/class/most/mostcore/devices/<mdev>/<channel>/set_buffer_size
+Date:		June 2015
+KernelVersion:	4.3
+Contact:	Christian Gromm <christian.gromm@microchip.com>
+Description:
+		This is to configure the size of a buffer of the current channel.
+Users:
+
+What:		/sys/class/most/mostcore/devices/<mdev>/<channel>/set_direction
+Date:		June 2015
+KernelVersion:	4.3
+Contact:	Christian Gromm <christian.gromm@microchip.com>
+Description:
+		This is to configure the direction of the current channel.
+		The following strings will be accepted:
+			'dir_tx',
+			'dir_rx'
+Users:
+
+What:		/sys/class/most/mostcore/devices/<mdev>/<channel>/set_datatype
+Date:		June 2015
+KernelVersion:	4.3
+Contact:	Christian Gromm <christian.gromm@microchip.com>
+Description:
+		This is to configure the data type of the current channel.
+		The following strings will be accepted:
+			'control',
+			'async',
+			'sync',
+			'isoc_avp'
+Users:
+
+What:		/sys/class/most/mostcore/devices/<mdev>/<channel>/set_subbuffer_size
+Date:		June 2015
+KernelVersion:	4.3
+Contact:	Christian Gromm <christian.gromm@microchip.com>
+Description:
+		This is to configure the subbuffer size of the current channel.
+Users:
+
+What:		/sys/class/most/mostcore/devices/<mdev>/<channel>/set_packets_per_xact
+Date:		June 2015
+KernelVersion:	4.3
+Contact:	Christian Gromm <christian.gromm@microchip.com>
+Description:
+		This is to configure the number of packets per transaction of
+		the current channel. This is only needed network interface
+		controller is attached via USB.
+Users:
+
+What:		/sys/class/most/mostcore/devices/<mdev>/<channel>/channel_starving
+Date:		June 2015
+KernelVersion:	4.3
+Contact:	Christian Gromm <christian.gromm@microchip.com>
+Description:
+		Indicates whether current channel ran out of buffers.
+Users:
diff --git a/drivers/staging/most/Documentation/driver_usage.txt b/drivers/staging/most/Documentation/driver_usage.txt
new file mode 100644
index 000000000..2fa8dea1d
--- /dev/null
+++ b/drivers/staging/most/Documentation/driver_usage.txt
@@ -0,0 +1,237 @@
+
+		Section 1 Overview
+
+The Media Oriented Systems Transport (MOST) driver gives Linux applications
+access a MOST network: The Automotive Information Backbone and the de-facto
+standard for high-bandwidth automotive multimedia networking.
+
+MOST defines the protocol, hardware and software layers necessary to allow
+for the efficient and low-cost transport of control, real-time and packet
+data using a single medium (physical layer). Media currently in use are
+fiber optics, unshielded twisted pair cables (UTP) and coax cables. MOST
+also supports various speed grades up to 150 Mbps.
+For more information on MOST, visit the MOST Cooperation website:
+www.mostcooperation.com.
+
+Cars continue to evolve into sophisticated consumer electronics platforms,
+increasing the demand for reliable and simple solutions to support audio,
+video and data communications. MOST can be used to connect multiple
+consumer devices via optical or electrical physical layers directly to one
+another or in a network configuration. As a synchronous network, MOST
+provides excellent Quality of Service and seamless connectivity for
+audio/video streaming. Therefore, the driver perfectly fits to the mission
+of Automotive Grade Linux to create open source software solutions for
+automotive applications.
+
+The MOST driver uses module stacking to divide the associated modules into
+three layers. From bottom up these layers are: the adapter layer, the core
+layer and the application layer. The core layer implements the MOST
+subsystem and consists basically of the module core.c and its API. It
+registers the MOST bus with the kernel's device model, handles the data
+routing through all three layers, the configuration of the driver, the
+representation of the configuration interface in sysfs and the buffer
+management.
+
+For each of the other two layers a set of modules is provided. Those can be
+arbitrarily combined with the core to meet the connectivity of the desired
+system architecture.
+
+A module of the adapter layer is basically a device driver for a different
+subsystem. It is registered with the core to connect the MOST subsystem to
+the attached network interface controller hardware. Hence, a given module
+of this layer is designed to handle exactly one of the peripheral
+interfaces (e.g. USB, MediaLB, I2C) the hardware provides.
+
+A module of the application layer is referred to as a core component,
+which kind of extends the core by providing connectivity to the user space.
+Applications, then, can access a MOST network via character devices, an
+ALSA soundcard, a Network adapter or a V4L2 capture device.
+
+To physically access MOST, an Intelligent Network Interface Controller
+(INIC) is needed. For more information on available controllers visit:
+www.microchip.com
+
+
+
+		Section 1.1 Adapter Layer
+
+The adapter layer contains a pool of device drivers. For each peripheral
+interface the hardware supports there is one suitable module that handles
+the interface. Adapter drivers encapsulate the peripheral interface
+specific knowledge of the MOST driver stack and provide an easy way of
+extending the number of supported interfaces. Currently the following
+interfaces are available:
+
+	1) MediaLB (DIM2)
+	   Host wants to communicate with hardware via MediaLB.
+
+	2) I2C
+	   Host wants to communicate with the hardware via I2C.
+
+	3) USB
+	   Host wants to communicate with the hardware via USB.
+
+Once an adapter driver recognizes a MOST device being attached, it
+registers it with the core, which, in turn, assigns the necessary members
+of the embedded struct device (e.g. the bus this device belongs to and
+attribute groups) and registers it with the kernel's device model.
+
+
+		Section 1.2 Core Layer
+
+This layer implements the MOST subsystem. It contains the core module and
+the header file most.h that exposes the API of the core. When inserted in
+the kernel, it registers the MOST bus_type with the kernel's device model
+and registers itself as a device driver for this bus. Besides these meta
+tasks the core populates the configuration directory for a registered MOST
+device (represented by struct most_interface) in sysfs and processes the
+configuration of the device's interface. The core layer also handles the
+buffer management and the data/message routing.
+
+
+		Section 1.3 Application Layer
+
+This layer contains a pool of device drivers that are components of the
+core designed to make up the userspace experience of the MOST driver stack.
+Depending on how an application is meant to interface the driver, one or
+more modules of this pool can be registered with the core. Currently the
+following components are available
+
+	1) Character Device
+	   Userspace can access the driver by means of character devices.
+
+	2) Networking
+	   Standard networking applications (e.g. iperf) can by used to access
+	   the driver via the networking subsystem.
+
+	3) Video4Linux (v4l2)
+	   Standard video applications (e.g. VLC) can by used to access the
+	   driver via the V4L subsystem.
+
+	4) Advanced Linux Sound Architecture (ALSA)
+	   Standard sound applications (e.g. aplay, arecord, audacity) can by
+	   used to access the driver via the ALSA subsystem.
+
+
+		Section 2 Usage of the MOST Driver
+
+		Section 2.1 Configuration and Data Link
+
+The driver is to be configured via configfs. Each loaded component kernel
+object (see section 1.3) registers a subsystem with configfs, which is used to
+configure and establish communication pathways (links) to attached devices on
+the bus. To do so, the user has to descend into the component's configuration
+directory and create a new directory (child config itmes). The name of this
+directory will be used as a reference for the link and it will contain the
+following attributes:
+
+	- buffer_size
+	  configure the buffer size for this channel
+	- subbuffer_size
+	  configure the sub-buffer size for this channel (needed for
+	  synchronous and isochrnous data)
+	- num_buffers
+	  configure number of buffers used for this channel
+	- datatype
+	  configure type of data that will travel over this channel
+	- direction
+	  configure whether this link will be an input or output
+	- dbr_size
+	  configure DBR data buffer size (this is used for MediaLB communication
+	  only)
+	- packets_per_xact
+	  configure the number of packets that will be collected from the
+	  network before being transmitted via USB (this is used for USB
+	  communication only)
+	- device
+	  name of the device the link is to be attached to
+	- channel
+	  name of the channel the link is to be attached to
+	- comp_params
+	  pass parameters needed by some components
+	- create_link
+	  write '1' to this attribute to trigger the creation of the link. In
+	  case of speculative configuration, the creation is post-poned until
+	  a physical device is being attached to the bus.
+	- destroy_link
+	  write '1' to this attribute to destroy an already established link
+
+
+See ABI/sysfs-bus-most.txt and ABI/configfs-most.txt
+
+
+		Section 2.2 Configure a Sound Card
+
+Setting up synchronous channels to be mapped as an ALSA sound adapter is a two
+step process. Firstly, a directory (child config group) has to be created
+inside the most_sound's configuration directory. This adapter dir will
+represent the sound adapter. The name of the directory is for user reference
+only and has no further influence, as all sound adapters will be given a static
+name in ALSA. The sound adapter will have the following attribute:
+
+	- create_card
+	  write '1' to this attribute to trigger the registration of the card
+	  with the ALSA subsystem.
+	  In case of speculative configuration, the creation is post-poned
+	  until a physical device is being attached to the bus.
+
+Secondly, links will have to be created inside the adapter dir as described in
+section 2.1. These links will become the PCM devices of the sound card. The
+name of a PCM device will be inherited from the directory name. When all
+channels have been configured and created, the sound card itself can be created
+by writing '1' to the create_card attribute.
+
+The sound component needs an additional parameter to determine the audio
+resolution that is going to be used.
+The following audio formats are available:
+
+	- "1x8" (Mono)
+	- "2x16" (16-bit stereo)
+	- "2x24" (24-bit stereo)
+	- "2x32" (32-bit stereo)
+	- "6x16" (16-bit surround 5.1)
+
+The resolution string has to be written to the link directory's comp_params
+attribute.
+
+		Section 2.3 USB Padding
+
+When transceiving synchronous or isochronous data, the number of packets
+per USB transaction and the sub-buffer size need to be configured. These
+values are needed for the driver to process buffer padding, as expected by
+hardware, which is for performance optimization purposes of the USB
+transmission.
+
+When transmitting synchronous data the allocated channel width needs to be
+written to 'subbuffer_size'. Additionally, the number of MOST frames that
+should travel to the host within one USB transaction need to be written to
+'packets_per_xact'.
+
+The driver, then, calculates the synchronous threshold as follows:
+
+	frame_size = subbuffer_size * packets_per_xact
+
+In case 'packets_per_xact' is set to 0xFF the maximum number of packets,
+allocated within one MOST frame, is calculated that fit into _one_ 512 byte
+USB full packet.
+
+	frame_size = floor(MTU_USB / bandwidth_sync) * bandwidth_sync
+
+This frame_size is the number of synchronous data within an USB
+transaction, which renders MTU_USB - frame_size bytes for padding.
+
+When transmitting isochronous AVP data the desired packet size needs to be
+written to 'subbuffer_size' and hardware will always expect two isochronous
+packets within one USB transaction. This renders
+
+	MTU_USB - (2 * subbuffer_size)
+
+bytes for padding.
+
+Note that at least (2 * subbuffer_size) bytes for isochronous data or
+(subbuffer_size * packts_per_xact) bytes for synchronous data need to
+be put in the transmission buffer and passed to the driver.
+
+Since adapter drivers are allowed to change a chosen configuration to best
+fit its constraints, it is recommended to always double check the
+configuration and read back the previously written files.