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/input/joydev/joystick-api.rst | 348 ++++++++++++++++++++++++++++ 1 file changed, 348 insertions(+) create mode 100644 Documentation/input/joydev/joystick-api.rst (limited to 'Documentation/input/joydev/joystick-api.rst') diff --git a/Documentation/input/joydev/joystick-api.rst b/Documentation/input/joydev/joystick-api.rst new file mode 100644 index 000000000..5db6dc6fe --- /dev/null +++ b/Documentation/input/joydev/joystick-api.rst @@ -0,0 +1,348 @@ +.. _joystick-api: + +===================== +Programming Interface +===================== + +:Author: Ragnar Hojland Espinosa - 7 Aug 1998 + +Introduction +============ + +.. important:: + This document describes legacy ``js`` interface. Newer clients are + encouraged to switch to the generic event (``evdev``) interface. + +The 1.0 driver uses a new, event based approach to the joystick driver. +Instead of the user program polling for the joystick values, the joystick +driver now reports only any changes of its state. See joystick-api.txt, +joystick.h and jstest.c included in the joystick package for more +information. The joystick device can be used in either blocking or +nonblocking mode, and supports select() calls. + +For backward compatibility the old (v0.x) interface is still included. +Any call to the joystick driver using the old interface will return values +that are compatible to the old interface. This interface is still limited +to 2 axes, and applications using it usually decode only 2 buttons, although +the driver provides up to 32. + +Initialization +============== + +Open the joystick device following the usual semantics (that is, with open). +Since the driver now reports events instead of polling for changes, +immediately after the open it will issue a series of synthetic events +(JS_EVENT_INIT) that you can read to obtain the initial state of the +joystick. + +By default, the device is opened in blocking mode:: + + int fd = open ("/dev/input/js0", O_RDONLY); + + +Event Reading +============= + +:: + + struct js_event e; + read (fd, &e, sizeof(e)); + +where js_event is defined as:: + + struct js_event { + __u32 time; /* event timestamp in milliseconds */ + __s16 value; /* value */ + __u8 type; /* event type */ + __u8 number; /* axis/button number */ + }; + +If the read is successful, it will return sizeof(e), unless you wanted to read +more than one event per read as described in section 3.1. + + +js_event.type +------------- + +The possible values of ``type`` are:: + + #define JS_EVENT_BUTTON 0x01 /* button pressed/released */ + #define JS_EVENT_AXIS 0x02 /* joystick moved */ + #define JS_EVENT_INIT 0x80 /* initial state of device */ + +As mentioned above, the driver will issue synthetic JS_EVENT_INIT ORed +events on open. That is, if it's issuing an INIT BUTTON event, the +current type value will be:: + + int type = JS_EVENT_BUTTON | JS_EVENT_INIT; /* 0x81 */ + +If you choose not to differentiate between synthetic or real events +you can turn off the JS_EVENT_INIT bits:: + + type &= ~JS_EVENT_INIT; /* 0x01 */ + + +js_event.number +--------------- + +The values of ``number`` correspond to the axis or button that +generated the event. Note that they carry separate numeration (that +is, you have both an axis 0 and a button 0). Generally, + + =============== ======= + Axis number + =============== ======= + 1st Axis X 0 + 1st Axis Y 1 + 2nd Axis X 2 + 2nd Axis Y 3 + ...and so on + =============== ======= + +Hats vary from one joystick type to another. Some can be moved in 8 +directions, some only in 4. The driver, however, always reports a hat as two +independent axes, even if the hardware doesn't allow independent movement. + + +js_event.value +-------------- + +For an axis, ``value`` is a signed integer between -32767 and +32767 +representing the position of the joystick along that axis. If you +don't read a 0 when the joystick is ``dead``, or if it doesn't span the +full range, you should recalibrate it (with, for example, jscal). + +For a button, ``value`` for a press button event is 1 and for a release +button event is 0. + +Though this:: + + if (js_event.type == JS_EVENT_BUTTON) { + buttons_state ^= (1 << js_event.number); + } + +may work well if you handle JS_EVENT_INIT events separately, + +:: + + if ((js_event.type & ~JS_EVENT_INIT) == JS_EVENT_BUTTON) { + if (js_event.value) + buttons_state |= (1 << js_event.number); + else + buttons_state &= ~(1 << js_event.number); + } + +is much safer since it can't lose sync with the driver. As you would +have to write a separate handler for JS_EVENT_INIT events in the first +snippet, this ends up being shorter. + + +js_event.time +------------- + +The time an event was generated is stored in ``js_event.time``. It's a time +in milliseconds since ... well, since sometime in the past. This eases the +task of detecting double clicks, figuring out if movement of axis and button +presses happened at the same time, and similar. + + +Reading +======= + +If you open the device in blocking mode, a read will block (that is, +wait) forever until an event is generated and effectively read. There +are two alternatives if you can't afford to wait forever (which is, +admittedly, a long time;) + + a) use select to wait until there's data to be read on fd, or + until it timeouts. There's a good example on the select(2) + man page. + + b) open the device in non-blocking mode (O_NONBLOCK) + + +O_NONBLOCK +---------- + +If read returns -1 when reading in O_NONBLOCK mode, this isn't +necessarily a "real" error (check errno(3)); it can just mean there +are no events pending to be read on the driver queue. You should read +all events on the queue (that is, until you get a -1). + +For example, + +:: + + while (1) { + while (read (fd, &e, sizeof(e)) > 0) { + process_event (e); + } + /* EAGAIN is returned when the queue is empty */ + if (errno != EAGAIN) { + /* error */ + } + /* do something interesting with processed events */ + } + +One reason for emptying the queue is that if it gets full you'll start +missing events since the queue is finite, and older events will get +overwritten. + +The other reason is that you want to know all that happened, and not +delay the processing till later. + +Why can the queue get full? Because you don't empty the queue as +mentioned, or because too much time elapses from one read to another +and too many events to store in the queue get generated. Note that +high system load may contribute to space those reads even more. + +If time between reads is enough to fill the queue and lose an event, +the driver will switch to startup mode and next time you read it, +synthetic events (JS_EVENT_INIT) will be generated to inform you of +the actual state of the joystick. + + +.. note:: + + As of version 1.2.8, the queue is circular and able to hold 64 + events. You can increment this size bumping up JS_BUFF_SIZE in + joystick.h and recompiling the driver. + + +In the above code, you might as well want to read more than one event +at a time using the typical read(2) functionality. For that, you would +replace the read above with something like:: + + struct js_event mybuffer[0xff]; + int i = read (fd, mybuffer, sizeof(mybuffer)); + +In this case, read would return -1 if the queue was empty, or some +other value in which the number of events read would be i / +sizeof(js_event) Again, if the buffer was full, it's a good idea to +process the events and keep reading it until you empty the driver queue. + + +IOCTLs +====== + +The joystick driver defines the following ioctl(2) operations:: + + /* function 3rd arg */ + #define JSIOCGAXES /* get number of axes char */ + #define JSIOCGBUTTONS /* get number of buttons char */ + #define JSIOCGVERSION /* get driver version int */ + #define JSIOCGNAME(len) /* get identifier string char */ + #define JSIOCSCORR /* set correction values &js_corr */ + #define JSIOCGCORR /* get correction values &js_corr */ + +For example, to read the number of axes:: + + char number_of_axes; + ioctl (fd, JSIOCGAXES, &number_of_axes); + + +JSIOGCVERSION +------------- + +JSIOGCVERSION is a good way to check in run-time whether the running +driver is 1.0+ and supports the event interface. If it is not, the +IOCTL will fail. For a compile-time decision, you can test the +JS_VERSION symbol:: + + #ifdef JS_VERSION + #if JS_VERSION > 0xsomething + + +JSIOCGNAME +---------- + +JSIOCGNAME(len) allows you to get the name string of the joystick - the same +as is being printed at boot time. The 'len' argument is the length of the +buffer provided by the application asking for the name. It is used to avoid +possible overrun should the name be too long:: + + char name[128]; + if (ioctl(fd, JSIOCGNAME(sizeof(name)), name) < 0) + strscpy(name, "Unknown", sizeof(name)); + printf("Name: %s\n", name); + + +JSIOC[SG]CORR +------------- + +For usage on JSIOC[SG]CORR I suggest you to look into jscal.c They are +not needed in a normal program, only in joystick calibration software +such as jscal or kcmjoy. These IOCTLs and data types aren't considered +to be in the stable part of the API, and therefore may change without +warning in following releases of the driver. + +Both JSIOCSCORR and JSIOCGCORR expect &js_corr to be able to hold +information for all axes. That is, struct js_corr corr[MAX_AXIS]; + +struct js_corr is defined as:: + + struct js_corr { + __s32 coef[8]; + __u16 prec; + __u16 type; + }; + +and ``type``:: + + #define JS_CORR_NONE 0x00 /* returns raw values */ + #define JS_CORR_BROKEN 0x01 /* broken line */ + + +Backward compatibility +====================== + +The 0.x joystick driver API is quite limited and its usage is deprecated. +The driver offers backward compatibility, though. Here's a quick summary:: + + struct JS_DATA_TYPE js; + while (1) { + if (read (fd, &js, JS_RETURN) != JS_RETURN) { + /* error */ + } + usleep (1000); + } + +As you can figure out from the example, the read returns immediately, +with the actual state of the joystick:: + + struct JS_DATA_TYPE { + int buttons; /* immediate button state */ + int x; /* immediate x axis value */ + int y; /* immediate y axis value */ + }; + +and JS_RETURN is defined as:: + + #define JS_RETURN sizeof(struct JS_DATA_TYPE) + +To test the state of the buttons, + +:: + + first_button_state = js.buttons & 1; + second_button_state = js.buttons & 2; + +The axis values do not have a defined range in the original 0.x driver, +except that the values are non-negative. The 1.2.8+ drivers use a +fixed range for reporting the values, 1 being the minimum, 128 the +center, and 255 maximum value. + +The v0.8.0.2 driver also had an interface for 'digital joysticks', (now +called Multisystem joysticks in this driver), under /dev/djsX. This driver +doesn't try to be compatible with that interface. + + +Final Notes +=========== + +:: + + ____/| Comments, additions, and specially corrections are welcome. + \ o.O| Documentation valid for at least version 1.2.8 of the joystick + =(_)= driver and as usual, the ultimate source for documentation is + U to "Use The Source Luke" or, at your convenience, Vojtech ;) -- cgit v1.2.3