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authorLibravatar Linus Torvalds <torvalds@linux-foundation.org>2023-02-21 18:24:12 -0800
committerLibravatar Linus Torvalds <torvalds@linux-foundation.org>2023-02-21 18:24:12 -0800
commit5b7c4cabbb65f5c469464da6c5f614cbd7f730f2 (patch)
treecc5c2d0a898769fd59549594fedb3ee6f84e59a0 /Documentation/driver-api/i3c
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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/i3c')
-rw-r--r--Documentation/driver-api/i3c/device-driver-api.rst9
-rw-r--r--Documentation/driver-api/i3c/index.rst11
-rw-r--r--Documentation/driver-api/i3c/master-driver-api.rst9
-rw-r--r--Documentation/driver-api/i3c/protocol.rst203
4 files changed, 232 insertions, 0 deletions
diff --git a/Documentation/driver-api/i3c/device-driver-api.rst b/Documentation/driver-api/i3c/device-driver-api.rst
new file mode 100644
index 000000000..85bc3381c
--- /dev/null
+++ b/Documentation/driver-api/i3c/device-driver-api.rst
@@ -0,0 +1,9 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+=====================
+I3C device driver API
+=====================
+
+.. kernel-doc:: include/linux/i3c/device.h
+
+.. kernel-doc:: drivers/i3c/device.c
diff --git a/Documentation/driver-api/i3c/index.rst b/Documentation/driver-api/i3c/index.rst
new file mode 100644
index 000000000..783d6dad0
--- /dev/null
+++ b/Documentation/driver-api/i3c/index.rst
@@ -0,0 +1,11 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+=============
+I3C subsystem
+=============
+
+.. toctree::
+
+ protocol
+ device-driver-api
+ master-driver-api
diff --git a/Documentation/driver-api/i3c/master-driver-api.rst b/Documentation/driver-api/i3c/master-driver-api.rst
new file mode 100644
index 000000000..332552b28
--- /dev/null
+++ b/Documentation/driver-api/i3c/master-driver-api.rst
@@ -0,0 +1,9 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+================================
+I3C master controller driver API
+================================
+
+.. kernel-doc:: drivers/i3c/master.c
+
+.. kernel-doc:: include/linux/i3c/master.h
diff --git a/Documentation/driver-api/i3c/protocol.rst b/Documentation/driver-api/i3c/protocol.rst
new file mode 100644
index 000000000..02653defa
--- /dev/null
+++ b/Documentation/driver-api/i3c/protocol.rst
@@ -0,0 +1,203 @@
+.. SPDX-License-Identifier: GPL-2.0
+
+============
+I3C protocol
+============
+
+Disclaimer
+==========
+
+This chapter will focus on aspects that matter to software developers. For
+everything hardware related (like how things are transmitted on the bus, how
+collisions are prevented, ...) please have a look at the I3C specification.
+
+This document is just a brief introduction to the I3C protocol and the concepts
+it brings to the table. If you need more information, please refer to the MIPI
+I3C specification (can be downloaded here
+https://resources.mipi.org/mipi-i3c-v1-download).
+
+Introduction
+============
+
+The I3C (pronounced 'eye-three-see') is a MIPI standardized protocol designed
+to overcome I2C limitations (limited speed, external signals needed for
+interrupts, no automatic detection of the devices connected to the bus, ...)
+while remaining power-efficient.
+
+I3C Bus
+=======
+
+An I3C bus is made of several I3C devices and possibly some I2C devices as
+well, but let's focus on I3C devices for now.
+
+An I3C device on the I3C bus can have one of the following roles:
+
+* Master: the device is driving the bus. It's the one in charge of initiating
+ transactions or deciding who is allowed to talk on the bus (slave generated
+ events are possible in I3C, see below).
+* Slave: the device acts as a slave, and is not able to send frames to another
+ slave on the bus. The device can still send events to the master on
+ its own initiative if the master allowed it.
+
+I3C is a multi-master protocol, so there might be several masters on a bus,
+though only one device can act as a master at a given time. In order to gain
+bus ownership, a master has to follow a specific procedure.
+
+Each device on the I3C bus has to be assigned a dynamic address to be able to
+communicate. Until this is done, the device should only respond to a limited
+set of commands. If it has a static address (also called legacy I2C address),
+the device can reply to I2C transfers.
+
+In addition to these per-device addresses, the protocol defines a broadcast
+address in order to address all devices on the bus.
+
+Once a dynamic address has been assigned to a device, this address will be used
+for any direct communication with the device. Note that even after being
+assigned a dynamic address, the device should still process broadcast messages.
+
+I3C Device discovery
+====================
+
+The I3C protocol defines a mechanism to automatically discover devices present
+on the bus, their capabilities and the functionalities they provide. In this
+regard I3C is closer to a discoverable bus like USB than it is to I2C or SPI.
+
+The discovery mechanism is called DAA (Dynamic Address Assignment), because it
+not only discovers devices but also assigns them a dynamic address.
+
+During DAA, each I3C device reports 3 important things:
+
+* BCR: Bus Characteristic Register. This 8-bit register describes the device bus
+ related capabilities
+* DCR: Device Characteristic Register. This 8-bit register describes the
+ functionalities provided by the device
+* Provisional ID: A 48-bit unique identifier. On a given bus there should be no
+ Provisional ID collision, otherwise the discovery mechanism may fail.
+
+I3C slave events
+================
+
+The I3C protocol allows slaves to generate events on their own, and thus allows
+them to take temporary control of the bus.
+
+This mechanism is called IBI for In Band Interrupts, and as stated in the name,
+it allows devices to generate interrupts without requiring an external signal.
+
+During DAA, each device on the bus has been assigned an address, and this
+address will serve as a priority identifier to determine who wins if 2 different
+devices are generating an interrupt at the same moment on the bus (the lower the
+dynamic address the higher the priority).
+
+Masters are allowed to inhibit interrupts if they want to. This inhibition
+request can be broadcast (applies to all devices) or sent to a specific
+device.
+
+I3C Hot-Join
+============
+
+The Hot-Join mechanism is similar to USB hotplug. This mechanism allows
+slaves to join the bus after it has been initialized by the master.
+
+This covers the following use cases:
+
+* the device is not powered when the bus is probed
+* the device is hotplugged on the bus through an extension board
+
+This mechanism is relying on slave events to inform the master that a new
+device joined the bus and is waiting for a dynamic address.
+
+The master is then free to address the request as it wishes: ignore it or
+assign a dynamic address to the slave.
+
+I3C transfer types
+==================
+
+If you omit SMBus (which is just a standardization on how to access registers
+exposed by I2C devices), I2C has only one transfer type.
+
+I3C defines 3 different classes of transfer in addition to I2C transfers which
+are here for backward compatibility with I2C devices.
+
+I3C CCC commands
+----------------
+
+CCC (Common Command Code) commands are meant to be used for anything that is
+related to bus management and all features that are common to a set of devices.
+
+CCC commands contain an 8-bit CCC ID describing the command that is executed.
+The MSB of this ID specifies whether this is a broadcast command (bit7 = 0) or a
+unicast one (bit7 = 1).
+
+The command ID can be followed by a payload. Depending on the command, this
+payload is either sent by the master sending the command (write CCC command),
+or sent by the slave receiving the command (read CCC command). Of course, read
+accesses only apply to unicast commands.
+Note that, when sending a CCC command to a specific device, the device address
+is passed in the first byte of the payload.
+
+The payload length is not explicitly passed on the bus, and should be extracted
+from the CCC ID.
+
+Note that vendors can use a dedicated range of CCC IDs for their own commands
+(0x61-0x7f and 0xe0-0xef).
+
+I3C Private SDR transfers
+-------------------------
+
+Private SDR (Single Data Rate) transfers should be used for anything that is
+device specific and does not require high transfer speed.
+
+It is the equivalent of I2C transfers but in the I3C world. Each transfer is
+passed the device address (dynamic address assigned during DAA), a payload
+and a direction.
+
+The only difference with I2C is that the transfer is much faster (typical clock
+frequency is 12.5MHz).
+
+I3C HDR commands
+----------------
+
+HDR commands should be used for anything that is device specific and requires
+high transfer speed.
+
+The first thing attached to an HDR command is the HDR mode. There are currently
+3 different modes defined by the I3C specification (refer to the specification
+for more details):
+
+* HDR-DDR: Double Data Rate mode
+* HDR-TSP: Ternary Symbol Pure. Only usable on busses with no I2C devices
+* HDR-TSL: Ternary Symbol Legacy. Usable on busses with I2C devices
+
+When sending an HDR command, the whole bus has to enter HDR mode, which is done
+using a broadcast CCC command.
+Once the bus has entered a specific HDR mode, the master sends the HDR command.
+An HDR command is made of:
+
+* one 16-bits command word in big endian
+* N 16-bits data words in big endian
+
+Those words may be wrapped with specific preambles/post-ambles which depend on
+the chosen HDR mode and are detailed here (see the specification for more
+details).
+
+The 16-bits command word is made of:
+
+* bit[15]: direction bit, read is 1, write is 0
+* bit[14:8]: command code. Identifies the command being executed, the amount of
+ data words and their meaning
+* bit[7:1]: I3C address of the device this command is addressed to
+* bit[0]: reserved/parity-bit
+
+Backward compatibility with I2C devices
+=======================================
+
+The I3C protocol has been designed to be backward compatible with I2C devices.
+This backward compatibility allows one to connect a mix of I2C and I3C devices
+on the same bus, though, in order to be really efficient, I2C devices should
+be equipped with 50 ns spike filters.
+
+I2C devices can't be discovered like I3C ones and have to be statically
+declared. In order to let the master know what these devices are capable of
+(both in terms of bus related limitations and functionalities), the software
+has to provide some information, which is done through the LVR (Legacy I2C
+Virtual Register).