diff options
author | 2023-02-21 18:24:12 -0800 | |
---|---|---|
committer | 2023-02-21 18:24:12 -0800 | |
commit | 5b7c4cabbb65f5c469464da6c5f614cbd7f730f2 (patch) | |
tree | cc5c2d0a898769fd59549594fedb3ee6f84e59a0 /Documentation/driver-api/usb/hotplug.rst | |
download | linux-5b7c4cabbb65f5c469464da6c5f614cbd7f730f2.tar.gz linux-5b7c4cabbb65f5c469464da6c5f614cbd7f730f2.zip |
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().
...
Diffstat (limited to 'Documentation/driver-api/usb/hotplug.rst')
-rw-r--r-- | Documentation/driver-api/usb/hotplug.rst | 154 |
1 files changed, 154 insertions, 0 deletions
diff --git a/Documentation/driver-api/usb/hotplug.rst b/Documentation/driver-api/usb/hotplug.rst new file mode 100644 index 000000000..c1e13107c --- /dev/null +++ b/Documentation/driver-api/usb/hotplug.rst @@ -0,0 +1,154 @@ +USB hotplugging +~~~~~~~~~~~~~~~ + +Linux Hotplugging +================= + + +In hotpluggable busses like USB (and Cardbus PCI), end-users plug devices +into the bus with power on. In most cases, users expect the devices to become +immediately usable. That means the system must do many things, including: + + - Find a driver that can handle the device. That may involve + loading a kernel module; newer drivers can use module-init-tools + to publish their device (and class) support to user utilities. + + - Bind a driver to that device. Bus frameworks do that using a + device driver's probe() routine. + + - Tell other subsystems to configure the new device. Print + queues may need to be enabled, networks brought up, disk + partitions mounted, and so on. In some cases these will + be driver-specific actions. + +This involves a mix of kernel mode and user mode actions. Making devices +be immediately usable means that any user mode actions can't wait for an +administrator to do them: the kernel must trigger them, either passively +(triggering some monitoring daemon to invoke a helper program) or +actively (calling such a user mode helper program directly). + +Those triggered actions must support a system's administrative policies; +such programs are called "policy agents" here. Typically they involve +shell scripts that dispatch to more familiar administration tools. + +Because some of those actions rely on information about drivers (metadata) +that is currently available only when the drivers are dynamically linked, +you get the best hotplugging when you configure a highly modular system. + +Kernel Hotplug Helper (``/sbin/hotplug``) +========================================= + +There is a kernel parameter: ``/proc/sys/kernel/hotplug``, which normally +holds the pathname ``/sbin/hotplug``. That parameter names a program +which the kernel may invoke at various times. + +The /sbin/hotplug program can be invoked by any subsystem as part of its +reaction to a configuration change, from a thread in that subsystem. +Only one parameter is required: the name of a subsystem being notified of +some kernel event. That name is used as the first key for further event +dispatch; any other argument and environment parameters are specified by +the subsystem making that invocation. + +Hotplug software and other resources is available at: + + http://linux-hotplug.sourceforge.net + +Mailing list information is also available at that site. + + +USB Policy Agent +================ + +The USB subsystem currently invokes ``/sbin/hotplug`` when USB devices +are added or removed from system. The invocation is done by the kernel +hub workqueue [hub_wq], or else as part of root hub initialization +(done by init, modprobe, kapmd, etc). Its single command line parameter +is the string "usb", and it passes these environment variables: + +========== ============================================ +ACTION ``add``, ``remove`` +PRODUCT USB vendor, product, and version codes (hex) +TYPE device class codes (decimal) +INTERFACE interface 0 class codes (decimal) +========== ============================================ + +If "usbdevfs" is configured, DEVICE and DEVFS are also passed. DEVICE is +the pathname of the device, and is useful for devices with multiple and/or +alternate interfaces that complicate driver selection. By design, USB +hotplugging is independent of ``usbdevfs``: you can do most essential parts +of USB device setup without using that filesystem, and without running a +user mode daemon to detect changes in system configuration. + +Currently available policy agent implementations can load drivers for +modules, and can invoke driver-specific setup scripts. The newest ones +leverage USB module-init-tools support. Later agents might unload drivers. + + +USB Modutils Support +==================== + +Current versions of module-init-tools will create a ``modules.usbmap`` file +which contains the entries from each driver's ``MODULE_DEVICE_TABLE``. Such +files can be used by various user mode policy agents to make sure all the +right driver modules get loaded, either at boot time or later. + +See ``linux/usb.h`` for full information about such table entries; or look +at existing drivers. Each table entry describes one or more criteria to +be used when matching a driver to a device or class of devices. The +specific criteria are identified by bits set in "match_flags", paired +with field values. You can construct the criteria directly, or with +macros such as these, and use driver_info to store more information:: + + USB_DEVICE (vendorId, productId) + ... matching devices with specified vendor and product ids + USB_DEVICE_VER (vendorId, productId, lo, hi) + ... like USB_DEVICE with lo <= productversion <= hi + USB_INTERFACE_INFO (class, subclass, protocol) + ... matching specified interface class info + USB_DEVICE_INFO (class, subclass, protocol) + ... matching specified device class info + +A short example, for a driver that supports several specific USB devices +and their quirks, might have a MODULE_DEVICE_TABLE like this:: + + static const struct usb_device_id mydriver_id_table[] = { + { USB_DEVICE (0x9999, 0xaaaa), driver_info: QUIRK_X }, + { USB_DEVICE (0xbbbb, 0x8888), driver_info: QUIRK_Y|QUIRK_Z }, + ... + { } /* end with an all-zeroes entry */ + }; + MODULE_DEVICE_TABLE(usb, mydriver_id_table); + +Most USB device drivers should pass these tables to the USB subsystem as +well as to the module management subsystem. Not all, though: some driver +frameworks connect using interfaces layered over USB, and so they won't +need such a struct usb_driver. + +Drivers that connect directly to the USB subsystem should be declared +something like this:: + + static struct usb_driver mydriver = { + .name = "mydriver", + .id_table = mydriver_id_table, + .probe = my_probe, + .disconnect = my_disconnect, + + /* + if using the usb chardev framework: + .minor = MY_USB_MINOR_START, + .fops = my_file_ops, + if exposing any operations through usbdevfs: + .ioctl = my_ioctl, + */ + }; + +When the USB subsystem knows about a driver's device ID table, it's used when +choosing drivers to probe(). The thread doing new device processing checks +drivers' device ID entries from the ``MODULE_DEVICE_TABLE`` against interface +and device descriptors for the device. It will only call ``probe()`` if there +is a match, and the third argument to ``probe()`` will be the entry that +matched. + +If you don't provide an ``id_table`` for your driver, then your driver may get +probed for each new device; the third parameter to ``probe()`` will be +``NULL``. |