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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/firmware-guide/acpi/gpio-properties.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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+.. SPDX-License-Identifier: GPL-2.0
+
+======================================
+_DSD Device Properties Related to GPIO
+======================================
+
+With the release of ACPI 5.1, the _DSD configuration object finally
+allows names to be given to GPIOs (and other things as well) returned
+by _CRS. Previously, we were only able to use an integer index to find
+the corresponding GPIO, which is pretty error prone (it depends on
+the _CRS output ordering, for example).
+
+With _DSD we can now query GPIOs using a name instead of an integer
+index, like the ASL example below shows::
+
+ // Bluetooth device with reset and shutdown GPIOs
+ Device (BTH)
+ {
+ Name (_HID, ...)
+
+ Name (_CRS, ResourceTemplate ()
+ {
+ GpioIo (Exclusive, PullUp, 0, 0, IoRestrictionOutputOnly,
+ "\\_SB.GPO0", 0, ResourceConsumer) { 15 }
+ GpioIo (Exclusive, PullUp, 0, 0, IoRestrictionOutputOnly,
+ "\\_SB.GPO0", 0, ResourceConsumer) { 27, 31 }
+ })
+
+ Name (_DSD, Package ()
+ {
+ ToUUID("daffd814-6eba-4d8c-8a91-bc9bbf4aa301"),
+ Package ()
+ {
+ Package () { "reset-gpios", Package () { ^BTH, 1, 1, 0 } },
+ Package () { "shutdown-gpios", Package () { ^BTH, 0, 0, 0 } },
+ }
+ })
+ }
+
+The format of the supported GPIO property is::
+
+ Package () { "name", Package () { ref, index, pin, active_low }}
+
+ref
+ The device that has _CRS containing GpioIo()/GpioInt() resources,
+ typically this is the device itself (BTH in our case).
+index
+ Index of the GpioIo()/GpioInt() resource in _CRS starting from zero.
+pin
+ Pin in the GpioIo()/GpioInt() resource. Typically this is zero.
+active_low
+ If 1, the GPIO is marked as active_low.
+
+Since ACPI GpioIo() resource does not have a field saying whether it is
+active low or high, the "active_low" argument can be used here. Setting
+it to 1 marks the GPIO as active low.
+
+Note, active_low in _DSD does not make sense for GpioInt() resource and
+must be 0. GpioInt() resource has its own means of defining it.
+
+In our Bluetooth example the "reset-gpios" refers to the second GpioIo()
+resource, second pin in that resource with the GPIO number of 31.
+
+The GpioIo() resource unfortunately doesn't explicitly provide an initial
+state of the output pin which driver should use during its initialization.
+
+Linux tries to use common sense here and derives the state from the bias
+and polarity settings. The table below shows the expectations:
+
++-------------+-------------+-----------------------------------------------+
+| Pull Bias | Polarity | Requested... |
++=============+=============+===============================================+
+| Implicit |
++-------------+-------------+-----------------------------------------------+
+| **Default** | x | AS IS (assumed firmware configured it for us) |
++-------------+-------------+-----------------------------------------------+
+| Explicit |
++-------------+-------------+-----------------------------------------------+
+| **None** | x | AS IS (assumed firmware configured it for us) |
+| | | with no Pull Bias |
++-------------+-------------+-----------------------------------------------+
+| **Up** | x (no _DSD) | |
+| +-------------+ as high, assuming non-active |
+| | Low | |
+| +-------------+-----------------------------------------------+
+| | High | as high, assuming active |
++-------------+-------------+-----------------------------------------------+
+| **Down** | x (no _DSD) | |
+| +-------------+ as low, assuming non-active |
+| | High | |
+| +-------------+-----------------------------------------------+
+| | Low | as low, assuming active |
++-------------+-------------+-----------------------------------------------+
+
+That said, for our above example the both GPIOs, since the bias setting
+is explicit and _DSD is present, will be treated as active with a high
+polarity and Linux will configure the pins in this state until a driver
+reprograms them differently.
+
+It is possible to leave holes in the array of GPIOs. This is useful in
+cases like with SPI host controllers where some chip selects may be
+implemented as GPIOs and some as native signals. For example a SPI host
+controller can have chip selects 0 and 2 implemented as GPIOs and 1 as
+native::
+
+ Package () {
+ "cs-gpios",
+ Package () {
+ ^GPIO, 19, 0, 0, // chip select 0: GPIO
+ 0, // chip select 1: native signal
+ ^GPIO, 20, 0, 0, // chip select 2: GPIO
+ }
+ }
+
+Note, that historically ACPI has no means of the GPIO polarity and thus
+the SPISerialBus() resource defines it on the per-chip basis. In order
+to avoid a chain of negations, the GPIO polarity is considered being
+Active High. Even for the cases when _DSD() is involved (see the example
+above) the GPIO CS polarity must be defined Active High to avoid ambiguity.
+
+Other supported properties
+==========================
+
+Following Device Tree compatible device properties are also supported by
+_DSD device properties for GPIO controllers:
+
+- gpio-hog
+- output-high
+- output-low
+- input
+- line-name
+
+Example::
+
+ Name (_DSD, Package () {
+ // _DSD Hierarchical Properties Extension UUID
+ ToUUID("dbb8e3e6-5886-4ba6-8795-1319f52a966b"),
+ Package () {
+ Package () { "hog-gpio8", "G8PU" }
+ }
+ })
+
+ Name (G8PU, Package () {
+ ToUUID("daffd814-6eba-4d8c-8a91-bc9bbf4aa301"),
+ Package () {
+ Package () { "gpio-hog", 1 },
+ Package () { "gpios", Package () { 8, 0 } },
+ Package () { "output-high", 1 },
+ Package () { "line-name", "gpio8-pullup" },
+ }
+ })
+
+- gpio-line-names
+
+The ``gpio-line-names`` declaration is a list of strings ("names"), which
+describes each line/pin of a GPIO controller/expander. This list, contained in
+a package, must be inserted inside the GPIO controller declaration of an ACPI
+table (typically inside the DSDT). The ``gpio-line-names`` list must respect the
+following rules (see also the examples):
+
+ - the first name in the list corresponds with the first line/pin of the GPIO
+ controller/expander
+ - the names inside the list must be consecutive (no "holes" are permitted)
+ - the list can be incomplete and can end before the last GPIO line: in
+ other words, it is not mandatory to fill all the GPIO lines
+ - empty names are allowed (two quotation marks ``""`` correspond to an empty
+ name)
+ - names inside one GPIO controller/expander must be unique
+
+Example of a GPIO controller of 16 lines, with an incomplete list with two
+empty names::
+
+ Package () {
+ "gpio-line-names",
+ Package () {
+ "pin_0",
+ "pin_1",
+ "",
+ "",
+ "pin_3",
+ "pin_4_push_button",
+ }
+ }
+
+At runtime, the above declaration produces the following result (using the
+"libgpiod" tools)::
+
+ root@debian:~# gpioinfo gpiochip4
+ gpiochip4 - 16 lines:
+ line 0: "pin_0" unused input active-high
+ line 1: "pin_1" unused input active-high
+ line 2: unnamed unused input active-high
+ line 3: unnamed unused input active-high
+ line 4: "pin_3" unused input active-high
+ line 5: "pin_4_push_button" unused input active-high
+ line 6: unnamed unused input active-high
+ line 7 unnamed unused input active-high
+ line 8: unnamed unused input active-high
+ line 9: unnamed unused input active-high
+ line 10: unnamed unused input active-high
+ line 11: unnamed unused input active-high
+ line 12: unnamed unused input active-high
+ line 13: unnamed unused input active-high
+ line 14: unnamed unused input active-high
+ line 15: unnamed unused input active-high
+ root@debian:~# gpiofind pin_4_push_button
+ gpiochip4 5
+ root@debian:~#
+
+Another example::
+
+ Package () {
+ "gpio-line-names",
+ Package () {
+ "SPI0_CS_N", "EXP2_INT", "MUX6_IO", "UART0_RXD",
+ "MUX7_IO", "LVL_C_A1", "MUX0_IO", "SPI1_MISO",
+ }
+ }
+
+See Documentation/devicetree/bindings/gpio/gpio.txt for more information
+about these properties.
+
+ACPI GPIO Mappings Provided by Drivers
+======================================
+
+There are systems in which the ACPI tables do not contain _DSD but provide _CRS
+with GpioIo()/GpioInt() resources and device drivers still need to work with
+them.
+
+In those cases ACPI device identification objects, _HID, _CID, _CLS, _SUB, _HRV,
+available to the driver can be used to identify the device and that is supposed
+to be sufficient to determine the meaning and purpose of all of the GPIO lines
+listed by the GpioIo()/GpioInt() resources returned by _CRS. In other words,
+the driver is supposed to know what to use the GpioIo()/GpioInt() resources for
+once it has identified the device. Having done that, it can simply assign names
+to the GPIO lines it is going to use and provide the GPIO subsystem with a
+mapping between those names and the ACPI GPIO resources corresponding to them.
+
+To do that, the driver needs to define a mapping table as a NULL-terminated
+array of struct acpi_gpio_mapping objects that each contains a name, a pointer
+to an array of line data (struct acpi_gpio_params) objects and the size of that
+array. Each struct acpi_gpio_params object consists of three fields,
+crs_entry_index, line_index, active_low, representing the index of the target
+GpioIo()/GpioInt() resource in _CRS starting from zero, the index of the target
+line in that resource starting from zero, and the active-low flag for that line,
+respectively, in analogy with the _DSD GPIO property format specified above.
+
+For the example Bluetooth device discussed previously the data structures in
+question would look like this::
+
+ static const struct acpi_gpio_params reset_gpio = { 1, 1, false };
+ static const struct acpi_gpio_params shutdown_gpio = { 0, 0, false };
+
+ static const struct acpi_gpio_mapping bluetooth_acpi_gpios[] = {
+ { "reset-gpios", &reset_gpio, 1 },
+ { "shutdown-gpios", &shutdown_gpio, 1 },
+ { }
+ };
+
+Next, the mapping table needs to be passed as the second argument to
+acpi_dev_add_driver_gpios() or its managed analogue that will
+register it with the ACPI device object pointed to by its first
+argument. That should be done in the driver's .probe() routine.
+On removal, the driver should unregister its GPIO mapping table by
+calling acpi_dev_remove_driver_gpios() on the ACPI device object where that
+table was previously registered.
+
+Using the _CRS fallback
+=======================
+
+If a device does not have _DSD or the driver does not create ACPI GPIO
+mapping, the Linux GPIO framework refuses to return any GPIOs. This is
+because the driver does not know what it actually gets. For example if we
+have a device like below::
+
+ Device (BTH)
+ {
+ Name (_HID, ...)
+
+ Name (_CRS, ResourceTemplate () {
+ GpioIo (Exclusive, PullNone, 0, 0, IoRestrictionNone,
+ "\\_SB.GPO0", 0, ResourceConsumer) { 15 }
+ GpioIo (Exclusive, PullNone, 0, 0, IoRestrictionNone,
+ "\\_SB.GPO0", 0, ResourceConsumer) { 27 }
+ })
+ }
+
+The driver might expect to get the right GPIO when it does::
+
+ desc = gpiod_get(dev, "reset", GPIOD_OUT_LOW);
+ if (IS_ERR(desc))
+ ...error handling...
+
+but since there is no way to know the mapping between "reset" and
+the GpioIo() in _CRS desc will hold ERR_PTR(-ENOENT).
+
+The driver author can solve this by passing the mapping explicitly
+(this is the recommended way and it's documented in the above chapter).
+
+The ACPI GPIO mapping tables should not contaminate drivers that are not
+knowing about which exact device they are servicing on. It implies that
+the ACPI GPIO mapping tables are hardly linked to an ACPI ID and certain
+objects, as listed in the above chapter, of the device in question.
+
+Getting GPIO descriptor
+=======================
+
+There are two main approaches to get GPIO resource from ACPI::
+
+ desc = gpiod_get(dev, connection_id, flags);
+ desc = gpiod_get_index(dev, connection_id, index, flags);
+
+We may consider two different cases here, i.e. when connection ID is
+provided and otherwise.
+
+Case 1::
+
+ desc = gpiod_get(dev, "non-null-connection-id", flags);
+ desc = gpiod_get_index(dev, "non-null-connection-id", index, flags);
+
+Case 2::
+
+ desc = gpiod_get(dev, NULL, flags);
+ desc = gpiod_get_index(dev, NULL, index, flags);
+
+Case 1 assumes that corresponding ACPI device description must have
+defined device properties and will prevent to getting any GPIO resources
+otherwise.
+
+Case 2 explicitly tells GPIO core to look for resources in _CRS.
+
+Be aware that gpiod_get_index() in cases 1 and 2, assuming that there
+are two versions of ACPI device description provided and no mapping is
+present in the driver, will return different resources. That's why a
+certain driver has to handle them carefully as explained in the previous
+chapter.