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, 453 insertions, 0 deletions

diff --git a/Documentation/input/event-codes.rst b/Documentation/input/event-codes.rst
new file mode 100644
index 000000000..b4557462e
--- /dev/null
+++ b/Documentation/input/event-codes.rst
@@ -0,0 +1,453 @@
+.. _input-event-codes:
+
+=================
+Input event codes
+=================
+
+
+The input protocol uses a map of types and codes to express input device values
+to userspace. This document describes the types and codes and how and when they
+may be used.
+
+A single hardware event generates multiple input events. Each input event
+contains the new value of a single data item. A special event type, EV_SYN, is
+used to separate input events into packets of input data changes occurring at
+the same moment in time. In the following, the term "event" refers to a single
+input event encompassing a type, code, and value.
+
+The input protocol is a stateful protocol. Events are emitted only when values
+of event codes have changed. However, the state is maintained within the Linux
+input subsystem; drivers do not need to maintain the state and may attempt to
+emit unchanged values without harm. Userspace may obtain the current state of
+event code values using the EVIOCG* ioctls defined in linux/input.h. The event
+reports supported by a device are also provided by sysfs in
+class/input/event*/device/capabilities/, and the properties of a device are
+provided in class/input/event*/device/properties.
+
+Event types
+===========
+
+Event types are groupings of codes under a logical input construct. Each
+type has a set of applicable codes to be used in generating events. See the
+Codes section for details on valid codes for each type.
+
+* EV_SYN:
+
+  - Used as markers to separate events. Events may be separated in time or in
+    space, such as with the multitouch protocol.
+
+* EV_KEY:
+
+  - Used to describe state changes of keyboards, buttons, or other key-like
+    devices.
+
+* EV_REL:
+
+  - Used to describe relative axis value changes, e.g. moving the mouse 5 units
+    to the left.
+
+* EV_ABS:
+
+  - Used to describe absolute axis value changes, e.g. describing the
+    coordinates of a touch on a touchscreen.
+
+* EV_MSC:
+
+  - Used to describe miscellaneous input data that do not fit into other types.
+
+* EV_SW:
+
+  - Used to describe binary state input switches.
+
+* EV_LED:
+
+  - Used to turn LEDs on devices on and off.
+
+* EV_SND:
+
+  - Used to output sound to devices.
+
+* EV_REP:
+
+  - Used for autorepeating devices.
+
+* EV_FF:
+
+  - Used to send force feedback commands to an input device.
+
+* EV_PWR:
+
+  - A special type for power button and switch input.
+
+* EV_FF_STATUS:
+
+  - Used to receive force feedback device status.
+
+Event codes
+===========
+
+Event codes define the precise type of event.
+
+EV_SYN
+------
+
+EV_SYN event values are undefined. Their usage is defined only by when they are
+sent in the evdev event stream.
+
+* SYN_REPORT:
+
+  - Used to synchronize and separate events into packets of input data changes
+    occurring at the same moment in time. For example, motion of a mouse may set
+    the REL_X and REL_Y values for one motion, then emit a SYN_REPORT. The next
+    motion will emit more REL_X and REL_Y values and send another SYN_REPORT.
+
+* SYN_CONFIG:
+
+  - TBD
+
+* SYN_MT_REPORT:
+
+  - Used to synchronize and separate touch events. See the
+    multi-touch-protocol.txt document for more information.
+
+* SYN_DROPPED:
+
+  - Used to indicate buffer overrun in the evdev client's event queue.
+    Client should ignore all events up to and including next SYN_REPORT
+    event and query the device (using EVIOCG* ioctls) to obtain its
+    current state.
+
+EV_KEY
+------
+
+EV_KEY events take the form KEY_<name> or BTN_<name>. For example, KEY_A is used
+to represent the 'A' key on a keyboard. When a key is depressed, an event with
+the key's code is emitted with value 1. When the key is released, an event is
+emitted with value 0. Some hardware send events when a key is repeated. These
+events have a value of 2. In general, KEY_<name> is used for keyboard keys, and
+BTN_<name> is used for other types of momentary switch events.
+
+A few EV_KEY codes have special meanings:
+
+* BTN_TOOL_<name>:
+
+  - These codes are used in conjunction with input trackpads, tablets, and
+    touchscreens. These devices may be used with fingers, pens, or other tools.
+    When an event occurs and a tool is used, the corresponding BTN_TOOL_<name>
+    code should be set to a value of 1. When the tool is no longer interacting
+    with the input device, the BTN_TOOL_<name> code should be reset to 0. All
+    trackpads, tablets, and touchscreens should use at least one BTN_TOOL_<name>
+    code when events are generated. Likewise all trackpads, tablets, and
+    touchscreens should export only one BTN_TOOL_<name> at a time. To not break
+    existing userspace, it is recommended to not switch tool in one EV_SYN frame
+    but first emitting the old BTN_TOOL_<name> at 0, then emit one SYN_REPORT
+    and then set the new BTN_TOOL_<name> at 1.
+
+* BTN_TOUCH:
+
+    BTN_TOUCH is used for touch contact. While an input tool is determined to be
+    within meaningful physical contact, the value of this property must be set
+    to 1. Meaningful physical contact may mean any contact, or it may mean
+    contact conditioned by an implementation defined property. For example, a
+    touchpad may set the value to 1 only when the touch pressure rises above a
+    certain value. BTN_TOUCH may be combined with BTN_TOOL_<name> codes. For
+    example, a pen tablet may set BTN_TOOL_PEN to 1 and BTN_TOUCH to 0 while the
+    pen is hovering over but not touching the tablet surface.
+
+Note: For appropriate function of the legacy mousedev emulation driver,
+BTN_TOUCH must be the first evdev code emitted in a synchronization frame.
+
+Note: Historically a touch device with BTN_TOOL_FINGER and BTN_TOUCH was
+interpreted as a touchpad by userspace, while a similar device without
+BTN_TOOL_FINGER was interpreted as a touchscreen. For backwards compatibility
+with current userspace it is recommended to follow this distinction. In the
+future, this distinction will be deprecated and the device properties ioctl
+EVIOCGPROP, defined in linux/input.h, will be used to convey the device type.
+
+* BTN_TOOL_FINGER, BTN_TOOL_DOUBLETAP, BTN_TOOL_TRIPLETAP, BTN_TOOL_QUADTAP:
+
+  - These codes denote one, two, three, and four finger interaction on a
+    trackpad or touchscreen. For example, if the user uses two fingers and moves
+    them on the touchpad in an effort to scroll content on screen,
+    BTN_TOOL_DOUBLETAP should be set to value 1 for the duration of the motion.
+    Note that all BTN_TOOL_<name> codes and the BTN_TOUCH code are orthogonal in
+    purpose. A trackpad event generated by finger touches should generate events
+    for one code from each group. At most only one of these BTN_TOOL_<name>
+    codes should have a value of 1 during any synchronization frame.
+
+Note: Historically some drivers emitted multiple of the finger count codes with
+a value of 1 in the same synchronization frame. This usage is deprecated.
+
+Note: In multitouch drivers, the input_mt_report_finger_count() function should
+be used to emit these codes. Please see multi-touch-protocol.txt for details.
+
+EV_REL
+------
+
+EV_REL events describe relative changes in a property. For example, a mouse may
+move to the left by a certain number of units, but its absolute position in
+space is unknown. If the absolute position is known, EV_ABS codes should be used
+instead of EV_REL codes.
+
+A few EV_REL codes have special meanings:
+
+* REL_WHEEL, REL_HWHEEL:
+
+  - These codes are used for vertical and horizontal scroll wheels,
+    respectively. The value is the number of detents moved on the wheel, the
+    physical size of which varies by device. For high-resolution wheels
+    this may be an approximation based on the high-resolution scroll events,
+    see REL_WHEEL_HI_RES. These event codes are legacy codes and
+    REL_WHEEL_HI_RES and REL_HWHEEL_HI_RES should be preferred where
+    available.
+
+* REL_WHEEL_HI_RES, REL_HWHEEL_HI_RES:
+
+  - High-resolution scroll wheel data. The accumulated value 120 represents
+    movement by one detent. For devices that do not provide high-resolution
+    scrolling, the value is always a multiple of 120. For devices with
+    high-resolution scrolling, the value may be a fraction of 120.
+
+    If a vertical scroll wheel supports high-resolution scrolling, this code
+    will be emitted in addition to REL_WHEEL or REL_HWHEEL. The REL_WHEEL
+    and REL_HWHEEL may be an approximation based on the high-resolution
+    scroll events. There is no guarantee that the high-resolution data
+    is a multiple of 120 at the time of an emulated REL_WHEEL or REL_HWHEEL
+    event.
+
+EV_ABS
+------
+
+EV_ABS events describe absolute changes in a property. For example, a touchpad
+may emit coordinates for a touch location.
+
+A few EV_ABS codes have special meanings:
+
+* ABS_DISTANCE:
+
+  - Used to describe the distance of a tool from an interaction surface. This
+    event should only be emitted while the tool is hovering, meaning in close
+    proximity of the device and while the value of the BTN_TOUCH code is 0. If
+    the input device may be used freely in three dimensions, consider ABS_Z
+    instead.
+  - BTN_TOOL_<name> should be set to 1 when the tool comes into detectable
+    proximity and set to 0 when the tool leaves detectable proximity.
+    BTN_TOOL_<name> signals the type of tool that is currently detected by the
+    hardware and is otherwise independent of ABS_DISTANCE and/or BTN_TOUCH.
+
+* ABS_PROFILE:
+
+  - Used to describe the state of a multi-value profile switch.  An event is
+    emitted only when the selected profile changes, indicating the newly
+    selected profile value.
+
+* ABS_MT_<name>:
+
+  - Used to describe multitouch input events. Please see
+    multi-touch-protocol.txt for details.
+
+* ABS_PRESSURE/ABS_MT_PRESSURE:
+
+   - For touch devices, many devices converted contact size into pressure.
+     A finger flattens with pressure, causing a larger contact area and thus
+     pressure and contact size are directly related. This is not the case
+     for other devices, for example digitizers and touchpads with a true
+     pressure sensor ("pressure pads").
+
+     A device should set the resolution of the axis to indicate whether the
+     pressure is in measurable units. If the resolution is zero, the
+     pressure data is in arbitrary units. If the resolution is non-zero, the
+     pressure data is in units/gram. For example, a value of 10 with a
+     resolution of 1 represents 10 gram, a value of 10 with a resolution of
+     1000 represents 10 microgram.
+
+EV_SW
+-----
+
+EV_SW events describe stateful binary switches. For example, the SW_LID code is
+used to denote when a laptop lid is closed.
+
+Upon binding to a device or resuming from suspend, a driver must report
+the current switch state. This ensures that the device, kernel, and userspace
+state is in sync.
+
+Upon resume, if the switch state is the same as before suspend, then the input
+subsystem will filter out the duplicate switch state reports. The driver does
+not need to keep the state of the switch at any time.
+
+EV_MSC
+------
+
+EV_MSC events are used for input and output events that do not fall under other
+categories.
+
+A few EV_MSC codes have special meaning:
+
+* MSC_TIMESTAMP:
+
+  - Used to report the number of microseconds since the last reset. This event
+    should be coded as an uint32 value, which is allowed to wrap around with
+    no special consequence. It is assumed that the time difference between two
+    consecutive events is reliable on a reasonable time scale (hours).
+    A reset to zero can happen, in which case the time since the last event is
+    unknown.  If the device does not provide this information, the driver must
+    not provide it to user space.
+
+EV_LED
+------
+
+EV_LED events are used for input and output to set and query the state of
+various LEDs on devices.
+
+EV_REP
+------
+
+EV_REP events are used for specifying autorepeating events.
+
+EV_SND
+------
+
+EV_SND events are used for sending sound commands to simple sound output
+devices.
+
+EV_FF
+-----
+
+EV_FF events are used to initialize a force feedback capable device and to cause
+such device to feedback.
+
+EV_PWR
+------
+
+EV_PWR events are a special type of event used specifically for power
+management. Its usage is not well defined. To be addressed later.
+
+Device properties
+=================
+
+Normally, userspace sets up an input device based on the data it emits,
+i.e., the event types. In the case of two devices emitting the same event
+types, additional information can be provided in the form of device
+properties.
+
+INPUT_PROP_DIRECT + INPUT_PROP_POINTER
+--------------------------------------
+
+The INPUT_PROP_DIRECT property indicates that device coordinates should be
+directly mapped to screen coordinates (not taking into account trivial
+transformations, such as scaling, flipping and rotating). Non-direct input
+devices require non-trivial transformation, such as absolute to relative
+transformation for touchpads. Typical direct input devices: touchscreens,
+drawing tablets; non-direct devices: touchpads, mice.
+
+The INPUT_PROP_POINTER property indicates that the device is not transposed
+on the screen and thus requires use of an on-screen pointer to trace user's
+movements.  Typical pointer devices: touchpads, tablets, mice; non-pointer
+device: touchscreen.
+
+If neither INPUT_PROP_DIRECT or INPUT_PROP_POINTER are set, the property is
+considered undefined and the device type should be deduced in the
+traditional way, using emitted event types.
+
+INPUT_PROP_BUTTONPAD
+--------------------
+
+For touchpads where the button is placed beneath the surface, such that
+pressing down on the pad causes a button click, this property should be
+set. Common in Clickpad notebooks and Macbooks from 2009 and onwards.
+
+Originally, the buttonpad property was coded into the bcm5974 driver
+version field under the name integrated button. For backwards
+compatibility, both methods need to be checked in userspace.
+
+INPUT_PROP_SEMI_MT
+------------------
+
+Some touchpads, most common between 2008 and 2011, can detect the presence
+of multiple contacts without resolving the individual positions; only the
+number of contacts and a rectangular shape is known. For such
+touchpads, the SEMI_MT property should be set.
+
+Depending on the device, the rectangle may enclose all touches, like a
+bounding box, or just some of them, for instance the two most recent
+touches. The diversity makes the rectangle of limited use, but some
+gestures can normally be extracted from it.
+
+If INPUT_PROP_SEMI_MT is not set, the device is assumed to be a true MT
+device.
+
+INPUT_PROP_TOPBUTTONPAD
+-----------------------
+
+Some laptops, most notably the Lenovo 40 series provide a trackstick
+device but do not have physical buttons associated with the trackstick
+device. Instead, the top area of the touchpad is marked to show
+visual/haptic areas for left, middle, right buttons intended to be used
+with the trackstick.
+
+If INPUT_PROP_TOPBUTTONPAD is set, userspace should emulate buttons
+accordingly. This property does not affect kernel behavior.
+The kernel does not provide button emulation for such devices but treats
+them as any other INPUT_PROP_BUTTONPAD device.
+
+INPUT_PROP_ACCELEROMETER
+------------------------
+
+Directional axes on this device (absolute and/or relative x, y, z) represent
+accelerometer data. Some devices also report gyroscope data, which devices
+can report through the rotational axes (absolute and/or relative rx, ry, rz).
+
+All other axes retain their meaning. A device must not mix
+regular directional axes and accelerometer axes on the same event node.
+
+Guidelines
+==========
+
+The guidelines below ensure proper single-touch and multi-finger functionality.
+For multi-touch functionality, see the multi-touch-protocol.rst document for
+more information.
+
+Mice
+----
+
+REL_{X,Y} must be reported when the mouse moves. BTN_LEFT must be used to report
+the primary button press. BTN_{MIDDLE,RIGHT,4,5,etc.} should be used to report
+further buttons of the device. REL_WHEEL and REL_HWHEEL should be used to report
+scroll wheel events where available.
+
+Touchscreens
+------------
+
+ABS_{X,Y} must be reported with the location of the touch. BTN_TOUCH must be
+used to report when a touch is active on the screen.
+BTN_{MOUSE,LEFT,MIDDLE,RIGHT} must not be reported as the result of touch
+contact. BTN_TOOL_<name> events should be reported where possible.
+
+For new hardware, INPUT_PROP_DIRECT should be set.
+
+Trackpads
+---------
+
+Legacy trackpads that only provide relative position information must report
+events like mice described above.
+
+Trackpads that provide absolute touch position must report ABS_{X,Y} for the
+location of the touch. BTN_TOUCH should be used to report when a touch is active
+on the trackpad. Where multi-finger support is available, BTN_TOOL_<name> should
+be used to report the number of touches active on the trackpad.
+
+For new hardware, INPUT_PROP_POINTER should be set.
+
+Tablets
+-------
+
+BTN_TOOL_<name> events must be reported when a stylus or other tool is active on
+the tablet. ABS_{X,Y} must be reported with the location of the tool. BTN_TOUCH
+should be used to report when the tool is in contact with the tablet.
+BTN_{STYLUS,STYLUS2} should be used to report buttons on the tool itself. Any
+button may be used for buttons on the tablet except BTN_{MOUSE,LEFT}.
+BTN_{0,1,2,etc} are good generic codes for unlabeled buttons. Do not use
+meaningful buttons, like BTN_FORWARD, unless the button is labeled for that
+purpose on the device.
+
+For new hardware, both INPUT_PROP_DIRECT and INPUT_PROP_POINTER should be set.