From 5b7c4cabbb65f5c469464da6c5f614cbd7f730f2 Mon Sep 17 00:00:00 2001 From: Linus Torvalds Date: Tue, 21 Feb 2023 18:24:12 -0800 Subject: Merge tag 'net-next-6.3' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next 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(). ... --- Documentation/hid/hiddev.rst | 251 +++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 251 insertions(+) create mode 100644 Documentation/hid/hiddev.rst (limited to 'Documentation/hid/hiddev.rst') diff --git a/Documentation/hid/hiddev.rst b/Documentation/hid/hiddev.rst new file mode 100644 index 000000000..caebc6266 --- /dev/null +++ b/Documentation/hid/hiddev.rst @@ -0,0 +1,251 @@ +================================================ +Care and feeding of your Human Interface Devices +================================================ + +Introduction +============ + +In addition to the normal input type HID devices, USB also uses the +human interface device protocols for things that are not really human +interfaces, but have similar sorts of communication needs. The two big +examples for this are power devices (especially uninterruptable power +supplies) and monitor control on higher end monitors. + +To support these disparate requirements, the Linux USB system provides +HID events to two separate interfaces: +* the input subsystem, which converts HID events into normal input +device interfaces (such as keyboard, mouse and joystick) and a +normalised event interface - see Documentation/input/input.rst +* the hiddev interface, which provides fairly raw HID events + +The data flow for a HID event produced by a device is something like +the following:: + + usb.c ---> hid-core.c ----> hid-input.c ----> [keyboard/mouse/joystick/event] + | + | + --> hiddev.c ----> POWER / MONITOR CONTROL + +In addition, other subsystems (apart from USB) can potentially feed +events into the input subsystem, but these have no effect on the HID +device interface. + +Using the HID Device Interface +============================== + +The hiddev interface is a char interface using the normal USB major, +with the minor numbers starting at 96 and finishing at 111. Therefore, +you need the following commands:: + + mknod /dev/usb/hiddev0 c 180 96 + mknod /dev/usb/hiddev1 c 180 97 + mknod /dev/usb/hiddev2 c 180 98 + mknod /dev/usb/hiddev3 c 180 99 + mknod /dev/usb/hiddev4 c 180 100 + mknod /dev/usb/hiddev5 c 180 101 + mknod /dev/usb/hiddev6 c 180 102 + mknod /dev/usb/hiddev7 c 180 103 + mknod /dev/usb/hiddev8 c 180 104 + mknod /dev/usb/hiddev9 c 180 105 + mknod /dev/usb/hiddev10 c 180 106 + mknod /dev/usb/hiddev11 c 180 107 + mknod /dev/usb/hiddev12 c 180 108 + mknod /dev/usb/hiddev13 c 180 109 + mknod /dev/usb/hiddev14 c 180 110 + mknod /dev/usb/hiddev15 c 180 111 + +So you point your hiddev compliant user-space program at the correct +interface for your device, and it all just works. + +Assuming that you have a hiddev compliant user-space program, of +course. If you need to write one, read on. + + +The HIDDEV API +============== + +This description should be read in conjunction with the HID +specification, freely available from https://www.usb.org, and +conveniently linked of http://www.linux-usb.org. + +The hiddev API uses a read() interface, and a set of ioctl() calls. + +HID devices exchange data with the host computer using data +bundles called "reports". Each report is divided into "fields", +each of which can have one or more "usages". In the hid-core, +each one of these usages has a single signed 32-bit value. + +read(): +------- + +This is the event interface. When the HID device's state changes, +it performs an interrupt transfer containing a report which contains +the changed value. The hid-core.c module parses the report, and +returns to hiddev.c the individual usages that have changed within +the report. In its basic mode, the hiddev will make these individual +usage changes available to the reader using a struct hiddev_event:: + + struct hiddev_event { + unsigned hid; + signed int value; + }; + +containing the HID usage identifier for the status that changed, and +the value that it was changed to. Note that the structure is defined +within , along with some other useful #defines and +structures. The HID usage identifier is a composite of the HID usage +page shifted to the 16 high order bits ORed with the usage code. The +behavior of the read() function can be modified using the HIDIOCSFLAG +ioctl() described below. + + +ioctl(): +-------- + +This is the control interface. There are a number of controls: + +HIDIOCGVERSION + - int (read) + + Gets the version code out of the hiddev driver. + +HIDIOCAPPLICATION + - (none) + +This ioctl call returns the HID application usage associated with the +HID device. The third argument to ioctl() specifies which application +index to get. This is useful when the device has more than one +application collection. If the index is invalid (greater or equal to +the number of application collections this device has) the ioctl +returns -1. You can find out beforehand how many application +collections the device has from the num_applications field from the +hiddev_devinfo structure. + +HIDIOCGCOLLECTIONINFO + - struct hiddev_collection_info (read/write) + +This returns a superset of the information above, providing not only +application collections, but all the collections the device has. It +also returns the level the collection lives in the hierarchy. +The user passes in a hiddev_collection_info struct with the index +field set to the index that should be returned. The ioctl fills in +the other fields. If the index is larger than the last collection +index, the ioctl returns -1 and sets errno to -EINVAL. + +HIDIOCGDEVINFO + - struct hiddev_devinfo (read) + +Gets a hiddev_devinfo structure which describes the device. + +HIDIOCGSTRING + - struct hiddev_string_descriptor (read/write) + +Gets a string descriptor from the device. The caller must fill in the +"index" field to indicate which descriptor should be returned. + +HIDIOCINITREPORT + - (none) + +Instructs the kernel to retrieve all input and feature report values +from the device. At this point, all the usage structures will contain +current values for the device, and will maintain it as the device +changes. Note that the use of this ioctl is unnecessary in general, +since later kernels automatically initialize the reports from the +device at attach time. + +HIDIOCGNAME + - string (variable length) + +Gets the device name + +HIDIOCGREPORT + - struct hiddev_report_info (write) + +Instructs the kernel to get a feature or input report from the device, +in order to selectively update the usage structures (in contrast to +INITREPORT). + +HIDIOCSREPORT + - struct hiddev_report_info (write) + +Instructs the kernel to send a report to the device. This report can +be filled in by the user through HIDIOCSUSAGE calls (below) to fill in +individual usage values in the report before sending the report in full +to the device. + +HIDIOCGREPORTINFO + - struct hiddev_report_info (read/write) + +Fills in a hiddev_report_info structure for the user. The report is +looked up by type (input, output or feature) and id, so these fields +must be filled in by the user. The ID can be absolute -- the actual +report id as reported by the device -- or relative -- +HID_REPORT_ID_FIRST for the first report, and (HID_REPORT_ID_NEXT | +report_id) for the next report after report_id. Without a priori +information about report ids, the right way to use this ioctl is to +use the relative IDs above to enumerate the valid IDs. The ioctl +returns non-zero when there is no more next ID. The real report ID is +filled into the returned hiddev_report_info structure. + +HIDIOCGFIELDINFO + - struct hiddev_field_info (read/write) + +Returns the field information associated with a report in a +hiddev_field_info structure. The user must fill in report_id and +report_type in this structure, as above. The field_index should also +be filled in, which should be a number from 0 and maxfield-1, as +returned from a previous HIDIOCGREPORTINFO call. + +HIDIOCGUCODE + - struct hiddev_usage_ref (read/write) + +Returns the usage_code in a hiddev_usage_ref structure, given that +its report type, report id, field index, and index within the +field have already been filled into the structure. + +HIDIOCGUSAGE + - struct hiddev_usage_ref (read/write) + +Returns the value of a usage in a hiddev_usage_ref structure. The +usage to be retrieved can be specified as above, or the user can +choose to fill in the report_type field and specify the report_id as +HID_REPORT_ID_UNKNOWN. In this case, the hiddev_usage_ref will be +filled in with the report and field information associated with this +usage if it is found. + +HIDIOCSUSAGE + - struct hiddev_usage_ref (write) + +Sets the value of a usage in an output report. The user fills in +the hiddev_usage_ref structure as above, but additionally fills in +the value field. + +HIDIOGCOLLECTIONINDEX + - struct hiddev_usage_ref (write) + +Returns the collection index associated with this usage. This +indicates where in the collection hierarchy this usage sits. + +HIDIOCGFLAG + - int (read) +HIDIOCSFLAG + - int (write) + +These operations respectively inspect and replace the mode flags +that influence the read() call above. The flags are as follows: + + HIDDEV_FLAG_UREF + - read() calls will now return + struct hiddev_usage_ref instead of struct hiddev_event. + This is a larger structure, but in situations where the + device has more than one usage in its reports with the + same usage code, this mode serves to resolve such + ambiguity. + + HIDDEV_FLAG_REPORT + - This flag can only be used in conjunction + with HIDDEV_FLAG_UREF. With this flag set, when the device + sends a report, a struct hiddev_usage_ref will be returned + to read() filled in with the report_type and report_id, but + with field_index set to FIELD_INDEX_NONE. This serves as + additional notification when the device has sent a report. -- cgit v1.2.3