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/i2c/functionality.rst | 156 ++++++++++++++++++++++++++++++++++++ 1 file changed, 156 insertions(+) create mode 100644 Documentation/i2c/functionality.rst (limited to 'Documentation/i2c/functionality.rst') diff --git a/Documentation/i2c/functionality.rst b/Documentation/i2c/functionality.rst new file mode 100644 index 000000000..377507c56 --- /dev/null +++ b/Documentation/i2c/functionality.rst @@ -0,0 +1,156 @@ +======================= +I2C/SMBus Functionality +======================= + +INTRODUCTION +------------ + +Because not every I2C or SMBus adapter implements everything in the +I2C specifications, a client can not trust that everything it needs +is implemented when it is given the option to attach to an adapter: +the client needs some way to check whether an adapter has the needed +functionality. + + +FUNCTIONALITY CONSTANTS +----------------------- + +For the most up-to-date list of functionality constants, please check +! + + =============================== ============================================== + I2C_FUNC_I2C Plain i2c-level commands (Pure SMBus + adapters typically can not do these) + I2C_FUNC_10BIT_ADDR Handles the 10-bit address extensions + I2C_FUNC_PROTOCOL_MANGLING Knows about the I2C_M_IGNORE_NAK, + I2C_M_REV_DIR_ADDR and I2C_M_NO_RD_ACK + flags (which modify the I2C protocol!) + I2C_FUNC_NOSTART Can skip repeated start sequence + I2C_FUNC_SMBUS_QUICK Handles the SMBus write_quick command + I2C_FUNC_SMBUS_READ_BYTE Handles the SMBus read_byte command + I2C_FUNC_SMBUS_WRITE_BYTE Handles the SMBus write_byte command + I2C_FUNC_SMBUS_READ_BYTE_DATA Handles the SMBus read_byte_data command + I2C_FUNC_SMBUS_WRITE_BYTE_DATA Handles the SMBus write_byte_data command + I2C_FUNC_SMBUS_READ_WORD_DATA Handles the SMBus read_word_data command + I2C_FUNC_SMBUS_WRITE_WORD_DATA Handles the SMBus write_byte_data command + I2C_FUNC_SMBUS_PROC_CALL Handles the SMBus process_call command + I2C_FUNC_SMBUS_READ_BLOCK_DATA Handles the SMBus read_block_data command + I2C_FUNC_SMBUS_WRITE_BLOCK_DATA Handles the SMBus write_block_data command + I2C_FUNC_SMBUS_READ_I2C_BLOCK Handles the SMBus read_i2c_block_data command + I2C_FUNC_SMBUS_WRITE_I2C_BLOCK Handles the SMBus write_i2c_block_data command + =============================== ============================================== + +A few combinations of the above flags are also defined for your convenience: + + ========================= ====================================== + I2C_FUNC_SMBUS_BYTE Handles the SMBus read_byte + and write_byte commands + I2C_FUNC_SMBUS_BYTE_DATA Handles the SMBus read_byte_data + and write_byte_data commands + I2C_FUNC_SMBUS_WORD_DATA Handles the SMBus read_word_data + and write_word_data commands + I2C_FUNC_SMBUS_BLOCK_DATA Handles the SMBus read_block_data + and write_block_data commands + I2C_FUNC_SMBUS_I2C_BLOCK Handles the SMBus read_i2c_block_data + and write_i2c_block_data commands + I2C_FUNC_SMBUS_EMUL Handles all SMBus commands that can be + emulated by a real I2C adapter (using + the transparent emulation layer) + ========================= ====================================== + +In kernel versions prior to 3.5 I2C_FUNC_NOSTART was implemented as +part of I2C_FUNC_PROTOCOL_MANGLING. + + +ADAPTER IMPLEMENTATION +---------------------- + +When you write a new adapter driver, you will have to implement a +function callback ``functionality``. Typical implementations are given +below. + +A typical SMBus-only adapter would list all the SMBus transactions it +supports. This example comes from the i2c-piix4 driver:: + + static u32 piix4_func(struct i2c_adapter *adapter) + { + return I2C_FUNC_SMBUS_QUICK | I2C_FUNC_SMBUS_BYTE | + I2C_FUNC_SMBUS_BYTE_DATA | I2C_FUNC_SMBUS_WORD_DATA | + I2C_FUNC_SMBUS_BLOCK_DATA; + } + +A typical full-I2C adapter would use the following (from the i2c-pxa +driver):: + + static u32 i2c_pxa_functionality(struct i2c_adapter *adap) + { + return I2C_FUNC_I2C | I2C_FUNC_SMBUS_EMUL; + } + +I2C_FUNC_SMBUS_EMUL includes all the SMBus transactions (with the +addition of I2C block transactions) which i2c-core can emulate using +I2C_FUNC_I2C without any help from the adapter driver. The idea is +to let the client drivers check for the support of SMBus functions +without having to care whether the said functions are implemented in +hardware by the adapter, or emulated in software by i2c-core on top +of an I2C adapter. + + +CLIENT CHECKING +--------------- + +Before a client tries to attach to an adapter, or even do tests to check +whether one of the devices it supports is present on an adapter, it should +check whether the needed functionality is present. The typical way to do +this is (from the lm75 driver):: + + static int lm75_detect(...) + { + (...) + if (!i2c_check_functionality(adapter, I2C_FUNC_SMBUS_BYTE_DATA | + I2C_FUNC_SMBUS_WORD_DATA)) + goto exit; + (...) + } + +Here, the lm75 driver checks if the adapter can do both SMBus byte data +and SMBus word data transactions. If not, then the driver won't work on +this adapter and there's no point in going on. If the check above is +successful, then the driver knows that it can call the following +functions: i2c_smbus_read_byte_data(), i2c_smbus_write_byte_data(), +i2c_smbus_read_word_data() and i2c_smbus_write_word_data(). As a rule of +thumb, the functionality constants you test for with +i2c_check_functionality() should match exactly the i2c_smbus_* functions +which you driver is calling. + +Note that the check above doesn't tell whether the functionalities are +implemented in hardware by the underlying adapter or emulated in +software by i2c-core. Client drivers don't have to care about this, as +i2c-core will transparently implement SMBus transactions on top of I2C +adapters. + + +CHECKING THROUGH /DEV +--------------------- + +If you try to access an adapter from a userspace program, you will have +to use the /dev interface. You will still have to check whether the +functionality you need is supported, of course. This is done using +the I2C_FUNCS ioctl. An example, adapted from the i2cdetect program, is +below:: + + int file; + if (file = open("/dev/i2c-0", O_RDWR) < 0) { + /* Some kind of error handling */ + exit(1); + } + if (ioctl(file, I2C_FUNCS, &funcs) < 0) { + /* Some kind of error handling */ + exit(1); + } + if (!(funcs & I2C_FUNC_SMBUS_QUICK)) { + /* Oops, the needed functionality (SMBus write_quick function) is + not available! */ + exit(1); + } + /* Now it is safe to use the SMBus write_quick command */ -- cgit v1.2.3