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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/hwmon/hwmon-kernel-api.rst
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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(). ...
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+The Linux Hardware Monitoring kernel API
+========================================
+
+Guenter Roeck
+
+Introduction
+------------
+
+This document describes the API that can be used by hardware monitoring
+drivers that want to use the hardware monitoring framework.
+
+This document does not describe what a hardware monitoring (hwmon) Driver or
+Device is. It also does not describe the API which can be used by user space
+to communicate with a hardware monitoring device. If you want to know this
+then please read the following file: Documentation/hwmon/sysfs-interface.rst.
+
+For additional guidelines on how to write and improve hwmon drivers, please
+also read Documentation/hwmon/submitting-patches.rst.
+
+The API
+-------
+Each hardware monitoring driver must #include <linux/hwmon.h> and, in most
+cases, <linux/hwmon-sysfs.h>. linux/hwmon.h declares the following
+register/unregister functions::
+
+ struct device *
+ hwmon_device_register_with_groups(struct device *dev, const char *name,
+ void *drvdata,
+ const struct attribute_group **groups);
+
+ struct device *
+ devm_hwmon_device_register_with_groups(struct device *dev,
+ const char *name, void *drvdata,
+ const struct attribute_group **groups);
+
+ struct device *
+ hwmon_device_register_with_info(struct device *dev,
+ const char *name, void *drvdata,
+ const struct hwmon_chip_info *info,
+ const struct attribute_group **extra_groups);
+
+ struct device *
+ devm_hwmon_device_register_with_info(struct device *dev,
+ const char *name,
+ void *drvdata,
+ const struct hwmon_chip_info *info,
+ const struct attribute_group **extra_groups);
+
+ void hwmon_device_unregister(struct device *dev);
+
+ void devm_hwmon_device_unregister(struct device *dev);
+
+ char *hwmon_sanitize_name(const char *name);
+
+ char *devm_hwmon_sanitize_name(struct device *dev, const char *name);
+
+hwmon_device_register_with_groups registers a hardware monitoring device.
+The first parameter of this function is a pointer to the parent device.
+The name parameter is a pointer to the hwmon device name. The registration
+function wil create a name sysfs attribute pointing to this name.
+The drvdata parameter is the pointer to the local driver data.
+hwmon_device_register_with_groups will attach this pointer to the newly
+allocated hwmon device. The pointer can be retrieved by the driver using
+dev_get_drvdata() on the hwmon device pointer. The groups parameter is
+a pointer to a list of sysfs attribute groups. The list must be NULL terminated.
+hwmon_device_register_with_groups creates the hwmon device with name attribute
+as well as all sysfs attributes attached to the hwmon device.
+This function returns a pointer to the newly created hardware monitoring device
+or PTR_ERR for failure.
+
+devm_hwmon_device_register_with_groups is similar to
+hwmon_device_register_with_groups. However, it is device managed, meaning the
+hwmon device does not have to be removed explicitly by the removal function.
+
+hwmon_device_register_with_info is the most comprehensive and preferred means
+to register a hardware monitoring device. It creates the standard sysfs
+attributes in the hardware monitoring core, letting the driver focus on reading
+from and writing to the chip instead of having to bother with sysfs attributes.
+The parent device parameter as well as the chip parameter must not be NULL. Its
+parameters are described in more detail below.
+
+devm_hwmon_device_register_with_info is similar to
+hwmon_device_register_with_info. However, it is device managed, meaning the
+hwmon device does not have to be removed explicitly by the removal function.
+
+hwmon_device_unregister deregisters a registered hardware monitoring device.
+The parameter of this function is the pointer to the registered hardware
+monitoring device structure. This function must be called from the driver
+remove function if the hardware monitoring device was registered with
+hwmon_device_register_with_groups or hwmon_device_register_with_info.
+
+devm_hwmon_device_unregister does not normally have to be called. It is only
+needed for error handling, and only needed if the driver probe fails after
+the call to devm_hwmon_device_register_with_groups or
+hwmon_device_register_with_info and if the automatic (device managed)
+removal would be too late.
+
+All supported hwmon device registration functions only accept valid device
+names. Device names including invalid characters (whitespace, '*', or '-')
+will be rejected. The 'name' parameter is mandatory.
+
+If the driver doesn't use a static device name (for example it uses
+dev_name()), and therefore cannot make sure the name only contains valid
+characters, hwmon_sanitize_name can be used. This convenience function
+will duplicate the string and replace any invalid characters with an
+underscore. It will allocate memory for the new string and it is the
+responsibility of the caller to release the memory when the device is
+removed.
+
+devm_hwmon_sanitize_name is the resource managed version of
+hwmon_sanitize_name; the memory will be freed automatically on device
+removal.
+
+Using devm_hwmon_device_register_with_info()
+--------------------------------------------
+
+hwmon_device_register_with_info() registers a hardware monitoring device.
+The parameters to this function are
+
+=============================================== ===============================================
+`struct device *dev` Pointer to parent device
+`const char *name` Device name
+`void *drvdata` Driver private data
+`const struct hwmon_chip_info *info` Pointer to chip description.
+`const struct attribute_group **extra_groups` Null-terminated list of additional non-standard
+ sysfs attribute groups.
+=============================================== ===============================================
+
+This function returns a pointer to the created hardware monitoring device
+on success and a negative error code for failure.
+
+The hwmon_chip_info structure looks as follows::
+
+ struct hwmon_chip_info {
+ const struct hwmon_ops *ops;
+ const struct hwmon_channel_info **info;
+ };
+
+It contains the following fields:
+
+* ops:
+ Pointer to device operations.
+* info:
+ NULL-terminated list of device channel descriptors.
+
+The list of hwmon operations is defined as::
+
+ struct hwmon_ops {
+ umode_t (*is_visible)(const void *, enum hwmon_sensor_types type,
+ u32 attr, int);
+ int (*read)(struct device *, enum hwmon_sensor_types type,
+ u32 attr, int, long *);
+ int (*write)(struct device *, enum hwmon_sensor_types type,
+ u32 attr, int, long);
+ };
+
+It defines the following operations.
+
+* is_visible:
+ Pointer to a function to return the file mode for each supported
+ attribute. This function is mandatory.
+
+* read:
+ Pointer to a function for reading a value from the chip. This function
+ is optional, but must be provided if any readable attributes exist.
+
+* write:
+ Pointer to a function for writing a value to the chip. This function is
+ optional, but must be provided if any writeable attributes exist.
+
+Each sensor channel is described with struct hwmon_channel_info, which is
+defined as follows::
+
+ struct hwmon_channel_info {
+ enum hwmon_sensor_types type;
+ u32 *config;
+ };
+
+It contains following fields:
+
+* type:
+ The hardware monitoring sensor type.
+
+ Supported sensor types are
+
+ ================== ==================================================
+ hwmon_chip A virtual sensor type, used to describe attributes
+ which are not bound to a specific input or output
+ hwmon_temp Temperature sensor
+ hwmon_in Voltage sensor
+ hwmon_curr Current sensor
+ hwmon_power Power sensor
+ hwmon_energy Energy sensor
+ hwmon_humidity Humidity sensor
+ hwmon_fan Fan speed sensor
+ hwmon_pwm PWM control
+ ================== ==================================================
+
+* config:
+ Pointer to a 0-terminated list of configuration values for each
+ sensor of the given type. Each value is a combination of bit values
+ describing the attributes supposed by a single sensor.
+
+As an example, here is the complete description file for a LM75 compatible
+sensor chip. The chip has a single temperature sensor. The driver wants to
+register with the thermal subsystem (HWMON_C_REGISTER_TZ), and it supports
+the update_interval attribute (HWMON_C_UPDATE_INTERVAL). The chip supports
+reading the temperature (HWMON_T_INPUT), it has a maximum temperature
+register (HWMON_T_MAX) as well as a maximum temperature hysteresis register
+(HWMON_T_MAX_HYST)::
+
+ static const u32 lm75_chip_config[] = {
+ HWMON_C_REGISTER_TZ | HWMON_C_UPDATE_INTERVAL,
+ 0
+ };
+
+ static const struct hwmon_channel_info lm75_chip = {
+ .type = hwmon_chip,
+ .config = lm75_chip_config,
+ };
+
+ static const u32 lm75_temp_config[] = {
+ HWMON_T_INPUT | HWMON_T_MAX | HWMON_T_MAX_HYST,
+ 0
+ };
+
+ static const struct hwmon_channel_info lm75_temp = {
+ .type = hwmon_temp,
+ .config = lm75_temp_config,
+ };
+
+ static const struct hwmon_channel_info *lm75_info[] = {
+ &lm75_chip,
+ &lm75_temp,
+ NULL
+ };
+
+ The HWMON_CHANNEL_INFO() macro can and should be used when possible.
+ With this macro, the above example can be simplified to
+
+ static const struct hwmon_channel_info *lm75_info[] = {
+ HWMON_CHANNEL_INFO(chip,
+ HWMON_C_REGISTER_TZ | HWMON_C_UPDATE_INTERVAL),
+ HWMON_CHANNEL_INFO(temp,
+ HWMON_T_INPUT | HWMON_T_MAX | HWMON_T_MAX_HYST),
+ NULL
+ };
+
+ The remaining declarations are as follows.
+
+ static const struct hwmon_ops lm75_hwmon_ops = {
+ .is_visible = lm75_is_visible,
+ .read = lm75_read,
+ .write = lm75_write,
+ };
+
+ static const struct hwmon_chip_info lm75_chip_info = {
+ .ops = &lm75_hwmon_ops,
+ .info = lm75_info,
+ };
+
+A complete list of bit values indicating individual attribute support
+is defined in include/linux/hwmon.h. Definition prefixes are as follows.
+
+=============== =================================================
+HWMON_C_xxxx Chip attributes, for use with hwmon_chip.
+HWMON_T_xxxx Temperature attributes, for use with hwmon_temp.
+HWMON_I_xxxx Voltage attributes, for use with hwmon_in.
+HWMON_C_xxxx Current attributes, for use with hwmon_curr.
+ Notice the prefix overlap with chip attributes.
+HWMON_P_xxxx Power attributes, for use with hwmon_power.
+HWMON_E_xxxx Energy attributes, for use with hwmon_energy.
+HWMON_H_xxxx Humidity attributes, for use with hwmon_humidity.
+HWMON_F_xxxx Fan speed attributes, for use with hwmon_fan.
+HWMON_PWM_xxxx PWM control attributes, for use with hwmon_pwm.
+=============== =================================================
+
+Driver callback functions
+-------------------------
+
+Each driver provides is_visible, read, and write functions. Parameters
+and return values for those functions are as follows::
+
+ umode_t is_visible_func(const void *data, enum hwmon_sensor_types type,
+ u32 attr, int channel)
+
+Parameters:
+ data:
+ Pointer to device private data structure.
+ type:
+ The sensor type.
+ attr:
+ Attribute identifier associated with a specific attribute.
+ For example, the attribute value for HWMON_T_INPUT would be
+ hwmon_temp_input. For complete mappings of bit fields to
+ attribute values please see include/linux/hwmon.h.
+ channel:
+ The sensor channel number.
+
+Return value:
+ The file mode for this attribute. Typically, this will be 0 (the
+ attribute will not be created), S_IRUGO, or 'S_IRUGO | S_IWUSR'.
+
+::
+
+ int read_func(struct device *dev, enum hwmon_sensor_types type,
+ u32 attr, int channel, long *val)
+
+Parameters:
+ dev:
+ Pointer to the hardware monitoring device.
+ type:
+ The sensor type.
+ attr:
+ Attribute identifier associated with a specific attribute.
+ For example, the attribute value for HWMON_T_INPUT would be
+ hwmon_temp_input. For complete mappings please see
+ include/linux/hwmon.h.
+ channel:
+ The sensor channel number.
+ val:
+ Pointer to attribute value.
+
+Return value:
+ 0 on success, a negative error number otherwise.
+
+::
+
+ int write_func(struct device *dev, enum hwmon_sensor_types type,
+ u32 attr, int channel, long val)
+
+Parameters:
+ dev:
+ Pointer to the hardware monitoring device.
+ type:
+ The sensor type.
+ attr:
+ Attribute identifier associated with a specific attribute.
+ For example, the attribute value for HWMON_T_INPUT would be
+ hwmon_temp_input. For complete mappings please see
+ include/linux/hwmon.h.
+ channel:
+ The sensor channel number.
+ val:
+ The value to write to the chip.
+
+Return value:
+ 0 on success, a negative error number otherwise.
+
+
+Driver-provided sysfs attributes
+--------------------------------
+
+If the hardware monitoring device is registered with
+hwmon_device_register_with_info or devm_hwmon_device_register_with_info,
+it is most likely not necessary to provide sysfs attributes. Only additional
+non-standard sysfs attributes need to be provided when one of those registration
+functions is used.
+
+The header file linux/hwmon-sysfs.h provides a number of useful macros to
+declare and use hardware monitoring sysfs attributes.
+
+In many cases, you can use the exsting define DEVICE_ATTR or its variants
+DEVICE_ATTR_{RW,RO,WO} to declare such attributes. This is feasible if an
+attribute has no additional context. However, in many cases there will be
+additional information such as a sensor index which will need to be passed
+to the sysfs attribute handling function.
+
+SENSOR_DEVICE_ATTR and SENSOR_DEVICE_ATTR_2 can be used to define attributes
+which need such additional context information. SENSOR_DEVICE_ATTR requires
+one additional argument, SENSOR_DEVICE_ATTR_2 requires two.
+
+Simplified variants of SENSOR_DEVICE_ATTR and SENSOR_DEVICE_ATTR_2 are available
+and should be used if standard attribute permissions and function names are
+feasible. Standard permissions are 0644 for SENSOR_DEVICE_ATTR[_2]_RW,
+0444 for SENSOR_DEVICE_ATTR[_2]_RO, and 0200 for SENSOR_DEVICE_ATTR[_2]_WO.
+Standard functions, similar to DEVICE_ATTR_{RW,RO,WO}, have _show and _store
+appended to the provided function name.
+
+SENSOR_DEVICE_ATTR and its variants define a struct sensor_device_attribute
+variable. This structure has the following fields::
+
+ struct sensor_device_attribute {
+ struct device_attribute dev_attr;
+ int index;
+ };
+
+You can use to_sensor_dev_attr to get the pointer to this structure from the
+attribute read or write function. Its parameter is the device to which the
+attribute is attached.
+
+SENSOR_DEVICE_ATTR_2 and its variants define a struct sensor_device_attribute_2
+variable, which is defined as follows::
+
+ struct sensor_device_attribute_2 {
+ struct device_attribute dev_attr;
+ u8 index;
+ u8 nr;
+ };
+
+Use to_sensor_dev_attr_2 to get the pointer to this structure. Its parameter
+is the device to which the attribute is attached.