diff options
Diffstat (limited to 'Documentation/driver-api')
| -rw-r--r-- | Documentation/driver-api/dma-buf.rst | 4 | ||||
| -rw-r--r-- | Documentation/driver-api/driver-model/device.rst | 4 | ||||
| -rw-r--r-- | Documentation/driver-api/driver-model/overview.rst | 2 | ||||
| -rw-r--r-- | Documentation/driver-api/index.rst | 1 | ||||
| -rw-r--r-- | Documentation/driver-api/ipmi.rst | 746 | ||||
| -rw-r--r-- | Documentation/driver-api/nvdimm/nvdimm.rst | 4 | ||||
| -rw-r--r-- | Documentation/driver-api/pm/cpuidle.rst | 5 | ||||
| -rw-r--r-- | Documentation/driver-api/pm/devices.rst | 199 | ||||
| -rw-r--r-- | Documentation/driver-api/thermal/cpu-idle-cooling.rst | 3 | ||||
| -rw-r--r-- | Documentation/driver-api/thermal/index.rst | 1 |
10 files changed, 887 insertions, 82 deletions
diff --git a/Documentation/driver-api/dma-buf.rst b/Documentation/driver-api/dma-buf.rst index c78db28519f7..63dec76d1d8d 100644 --- a/Documentation/driver-api/dma-buf.rst +++ b/Documentation/driver-api/dma-buf.rst @@ -11,7 +11,7 @@ course not limited to GPU use cases. The three main components of this are: (1) dma-buf, representing a sg_table and exposed to userspace as a file descriptor to allow passing between devices, (2) fence, which provides a mechanism to signal when -one device as finished access, and (3) reservation, which manages the +one device has finished access, and (3) reservation, which manages the shared or exclusive fence(s) associated with the buffer. Shared DMA Buffers @@ -31,7 +31,7 @@ The exporter - implements and manages operations in :c:type:`struct dma_buf_ops <dma_buf_ops>` for the buffer, - allows other users to share the buffer by using dma_buf sharing APIs, - - manages the details of buffer allocation, wrapped int a :c:type:`struct + - manages the details of buffer allocation, wrapped in a :c:type:`struct dma_buf <dma_buf>`, - decides about the actual backing storage where this allocation happens, - and takes care of any migration of scatterlist - for all (shared) users of diff --git a/Documentation/driver-api/driver-model/device.rst b/Documentation/driver-api/driver-model/device.rst index 2b868d49d349..b9b022371e85 100644 --- a/Documentation/driver-api/driver-model/device.rst +++ b/Documentation/driver-api/driver-model/device.rst @@ -50,10 +50,10 @@ Attributes Attributes of devices can be exported by a device driver through sysfs. -Please see Documentation/filesystems/sysfs.txt for more information +Please see Documentation/filesystems/sysfs.rst for more information on how sysfs works. -As explained in Documentation/kobject.txt, device attributes must be +As explained in Documentation/core-api/kobject.rst, device attributes must be created before the KOBJ_ADD uevent is generated. The only way to realize that is by defining an attribute group. diff --git a/Documentation/driver-api/driver-model/overview.rst b/Documentation/driver-api/driver-model/overview.rst index d4d1e9b40e0c..e98d0ab4a9b6 100644 --- a/Documentation/driver-api/driver-model/overview.rst +++ b/Documentation/driver-api/driver-model/overview.rst @@ -121,4 +121,4 @@ device-specific data or tunable interfaces. More information about the sysfs directory layout can be found in the other documents in this directory and in the file -Documentation/filesystems/sysfs.txt. +Documentation/filesystems/sysfs.rst. diff --git a/Documentation/driver-api/index.rst b/Documentation/driver-api/index.rst index d4e78cb3ef4d..20c431c8e7be 100644 --- a/Documentation/driver-api/index.rst +++ b/Documentation/driver-api/index.rst @@ -39,6 +39,7 @@ available subsections can be seen below. spi i2c ipmb + ipmi i3c/index interconnect devfreq diff --git a/Documentation/driver-api/ipmi.rst b/Documentation/driver-api/ipmi.rst new file mode 100644 index 000000000000..5ef1047e2e66 --- /dev/null +++ b/Documentation/driver-api/ipmi.rst @@ -0,0 +1,746 @@ +===================== +The Linux IPMI Driver +===================== + +:Author: Corey Minyard <minyard@mvista.com> / <minyard@acm.org> + +The Intelligent Platform Management Interface, or IPMI, is a +standard for controlling intelligent devices that monitor a system. +It provides for dynamic discovery of sensors in the system and the +ability to monitor the sensors and be informed when the sensor's +values change or go outside certain boundaries. It also has a +standardized database for field-replaceable units (FRUs) and a watchdog +timer. + +To use this, you need an interface to an IPMI controller in your +system (called a Baseboard Management Controller, or BMC) and +management software that can use the IPMI system. + +This document describes how to use the IPMI driver for Linux. If you +are not familiar with IPMI itself, see the web site at +http://www.intel.com/design/servers/ipmi/index.htm. IPMI is a big +subject and I can't cover it all here! + +Configuration +------------- + +The Linux IPMI driver is modular, which means you have to pick several +things to have it work right depending on your hardware. Most of +these are available in the 'Character Devices' menu then the IPMI +menu. + +No matter what, you must pick 'IPMI top-level message handler' to use +IPMI. What you do beyond that depends on your needs and hardware. + +The message handler does not provide any user-level interfaces. +Kernel code (like the watchdog) can still use it. If you need access +from userland, you need to select 'Device interface for IPMI' if you +want access through a device driver. + +The driver interface depends on your hardware. If your system +properly provides the SMBIOS info for IPMI, the driver will detect it +and just work. If you have a board with a standard interface (These +will generally be either "KCS", "SMIC", or "BT", consult your hardware +manual), choose the 'IPMI SI handler' option. A driver also exists +for direct I2C access to the IPMI management controller. Some boards +support this, but it is unknown if it will work on every board. For +this, choose 'IPMI SMBus handler', but be ready to try to do some +figuring to see if it will work on your system if the SMBIOS/APCI +information is wrong or not present. It is fairly safe to have both +these enabled and let the drivers auto-detect what is present. + +You should generally enable ACPI on your system, as systems with IPMI +can have ACPI tables describing them. + +If you have a standard interface and the board manufacturer has done +their job correctly, the IPMI controller should be automatically +detected (via ACPI or SMBIOS tables) and should just work. Sadly, +many boards do not have this information. The driver attempts +standard defaults, but they may not work. If you fall into this +situation, you need to read the section below named 'The SI Driver' or +"The SMBus Driver" on how to hand-configure your system. + +IPMI defines a standard watchdog timer. You can enable this with the +'IPMI Watchdog Timer' config option. If you compile the driver into +the kernel, then via a kernel command-line option you can have the +watchdog timer start as soon as it initializes. It also have a lot +of other options, see the 'Watchdog' section below for more details. +Note that you can also have the watchdog continue to run if it is +closed (by default it is disabled on close). Go into the 'Watchdog +Cards' menu, enable 'Watchdog Timer Support', and enable the option +'Disable watchdog shutdown on close'. + +IPMI systems can often be powered off using IPMI commands. Select +'IPMI Poweroff' to do this. The driver will auto-detect if the system +can be powered off by IPMI. It is safe to enable this even if your +system doesn't support this option. This works on ATCA systems, the +Radisys CPI1 card, and any IPMI system that supports standard chassis +management commands. + +If you want the driver to put an event into the event log on a panic, +enable the 'Generate a panic event to all BMCs on a panic' option. If +you want the whole panic string put into the event log using OEM +events, enable the 'Generate OEM events containing the panic string' +option. You can also enable these dynamically by setting the module +parameter named "panic_op" in the ipmi_msghandler module to "event" +or "string". Setting that parameter to "none" disables this function. + +Basic Design +------------ + +The Linux IPMI driver is designed to be very modular and flexible, you +only need to take the pieces you need and you can use it in many +different ways. Because of that, it's broken into many chunks of +code. These chunks (by module name) are: + +ipmi_msghandler - This is the central piece of software for the IPMI +system. It handles all messages, message timing, and responses. The +IPMI users tie into this, and the IPMI physical interfaces (called +System Management Interfaces, or SMIs) also tie in here. This +provides the kernelland interface for IPMI, but does not provide an +interface for use by application processes. + +ipmi_devintf - This provides a userland IOCTL interface for the IPMI +driver, each open file for this device ties in to the message handler +as an IPMI user. + +ipmi_si - A driver for various system interfaces. This supports KCS, +SMIC, and BT interfaces. Unless you have an SMBus interface or your +own custom interface, you probably need to use this. + +ipmi_ssif - A driver for accessing BMCs on the SMBus. It uses the +I2C kernel driver's SMBus interfaces to send and receive IPMI messages +over the SMBus. + +ipmi_powernv - A driver for access BMCs on POWERNV systems. + +ipmi_watchdog - IPMI requires systems to have a very capable watchdog +timer. This driver implements the standard Linux watchdog timer +interface on top of the IPMI message handler. + +ipmi_poweroff - Some systems support the ability to be turned off via +IPMI commands. + +bt-bmc - This is not part of the main driver, but instead a driver for +accessing a BMC-side interface of a BT interface. It is used on BMCs +running Linux to provide an interface to the host. + +These are all individually selectable via configuration options. + +Much documentation for the interface is in the include files. The +IPMI include files are: + +linux/ipmi.h - Contains the user interface and IOCTL interface for IPMI. + +linux/ipmi_smi.h - Contains the interface for system management interfaces +(things that interface to IPMI controllers) to use. + +linux/ipmi_msgdefs.h - General definitions for base IPMI messaging. + + +Addressing +---------- + +The IPMI addressing works much like IP addresses, you have an overlay +to handle the different address types. The overlay is:: + + struct ipmi_addr + { + int addr_type; + short channel; + char data[IPMI_MAX_ADDR_SIZE]; + }; + +The addr_type determines what the address really is. The driver +currently understands two different types of addresses. + +"System Interface" addresses are defined as:: + + struct ipmi_system_interface_addr + { + int addr_type; + short channel; + }; + +and the type is IPMI_SYSTEM_INTERFACE_ADDR_TYPE. This is used for talking +straight to the BMC on the current card. The channel must be +IPMI_BMC_CHANNEL. + +Messages that are destined to go out on the IPMB bus use the +IPMI_IPMB_ADDR_TYPE address type. The format is:: + + struct ipmi_ipmb_addr + { + int addr_type; + short channel; + unsigned char slave_addr; + unsigned char lun; + }; + +The "channel" here is generally zero, but some devices support more +than one channel, it corresponds to the channel as defined in the IPMI +spec. + + +Messages +-------- + +Messages are defined as:: + + struct ipmi_msg + { + unsigned char netfn; + unsigned char lun; + unsigned char cmd; + unsigned char *data; + int data_len; + }; + +The driver takes care of adding/stripping the header information. The +data portion is just the data to be send (do NOT put addressing info +here) or the response. Note that the completion code of a response is +the first item in "data", it is not stripped out because that is how +all the messages are defined in the spec (and thus makes counting the +offsets a little easier :-). + +When using the IOCTL interface from userland, you must provide a block +of data for "data", fill it, and set data_len to the length of the +block of data, even when receiving messages. Otherwise the driver +will have no place to put the message. + +Messages coming up from the message handler in kernelland will come in +as:: + + struct ipmi_recv_msg + { + struct list_head link; + + /* The type of message as defined in the "Receive Types" + defines above. */ + int recv_type; + + ipmi_user_t *user; + struct ipmi_addr addr; + long msgid; + struct ipmi_msg msg; + + /* Call this when done with the message. It will presumably free + the message and do any other necessary cleanup. */ + void (*done)(struct ipmi_recv_msg *msg); + + /* Place-holder for the data, don't make any assumptions about + the size or existence of this, since it may change. */ + unsigned char msg_data[IPMI_MAX_MSG_LENGTH]; + }; + +You should look at the receive type and handle the message +appropriately. + + +The Upper Layer Interface (Message Handler) +------------------------------------------- + +The upper layer of the interface provides the users with a consistent +view of the IPMI interfaces. It allows multiple SMI interfaces to be +addressed (because some boards actually have multiple BMCs on them) +and the user should not have to care what type of SMI is below them. + + +Watching For Interfaces +^^^^^^^^^^^^^^^^^^^^^^^ + +When your code comes up, the IPMI driver may or may not have detected +if IPMI devices exist. So you might have to defer your setup until +the device is detected, or you might be able to do it immediately. +To handle this, and to allow for discovery, you register an SMI +watcher with ipmi_smi_watcher_register() to iterate over interfaces +and tell you when they come and go. + + +Creating the User +^^^^^^^^^^^^^^^^^ + +To use the message handler, you must first create a user using +ipmi_create_user. The interface number specifies which SMI you want +to connect to, and you must supply callback functions to be called +when data comes in. The callback function can run at interrupt level, +so be careful using the callbacks. This also allows to you pass in a +piece of data, the handler_data, that will be passed back to you on +all calls. + +Once you are done, call ipmi_destroy_user() to get rid of the user. + +From userland, opening the device automatically creates a user, and +closing the device automatically destroys the user. + + +Messaging +^^^^^^^^^ + +To send a message from kernel-land, the ipmi_request_settime() call does +pretty much all message handling. Most of the parameter are +self-explanatory. However, it takes a "msgid" parameter. This is NOT +the sequence number of messages. It is simply a long value that is +passed back when the response for the message is returned. You may +use it for anything you like. + +Responses come back in the function pointed to by the ipmi_recv_hndl +field of the "handler" that you passed in to ipmi_create_user(). +Remember again, these may be running at interrupt level. Remember to +look at the receive type, too. + +From userland, you fill out an ipmi_req_t structure and use the +IPMICTL_SEND_COMMAND ioctl. For incoming stuff, you can use select() +or poll() to wait for messages to come in. However, you cannot use +read() to get them, you must call the IPMICTL_RECEIVE_MSG with the +ipmi_recv_t structure to actually get the message. Remember that you +must supply a pointer to a block of data in the msg.data field, and +you must fill in the msg.data_len field with the size of the data. +This gives the receiver a place to actually put the message. + +If the message cannot fit into the data you provide, you will get an +EMSGSIZE error and the driver will leave the data in the receive +queue. If you want to get it and have it truncate the message, us +the IPMICTL_RECEIVE_MSG_TRUNC ioctl. + +When you send a command (which is defined by the lowest-order bit of +the netfn per the IPMI spec) on the IPMB bus, the driver will +automatically assign the sequence number to the command and save the +command. If the response is not receive in the IPMI-specified 5 +seconds, it will generate a response automatically saying the command +timed out. If an unsolicited response comes in (if it was after 5 +seconds, for instance), that response will be ignored. + +In kernelland, after you receive a message and are done with it, you +MUST call ipmi_free_recv_msg() on it, or you will leak messages. Note +that you should NEVER mess with the "done" field of a message, that is +required to properly clean up the message. + +Note that when sending, there is an ipmi_request_supply_msgs() call +that lets you supply the smi and receive message. This is useful for +pieces of code that need to work even if the system is out of buffers +(the watchdog timer uses this, for instance). You supply your own +buffer and own free routines. This is not recommended for normal use, +though, since it is tricky to manage your own buffers. + + +Events and Incoming Commands +^^^^^^^^^^^^^^^^^^^^^^^^^^^^ + +The driver takes care of polling for IPMI events and receiving +commands (commands are messages that are not responses, they are +commands that other things on the IPMB bus have sent you). To receive +these, you must register for them, they will not automatically be sent +to you. + +To receive events, you must call ipmi_set_gets_events() and set the +"val" to non-zero. Any events that have been received by the driver +since startup will immediately be delivered to the first user that +registers for events. After that, if multiple users are registered +for events, they will all receive all events that come in. + +For receiving commands, you have to individually register commands you +want to receive. Call ipmi_register_for_cmd() and supply the netfn +and command name for each command you want to receive. You also +specify a bitmask of the channels you want to receive the command from +(or use IPMI_CHAN_ALL for all channels if you don't care). Only one +user may be registered for each netfn/cmd/channel, but different users +may register for different commands, or the same command if the +channel bitmasks do not overlap. + +From userland, equivalent IOCTLs are provided to do these functions. + + +The Lower Layer (SMI) Interface +------------------------------- + +As mentioned before, multiple SMI interfaces may be registered to the +message handler, each of these is assigned an interface number when +they register with the message handler. They are generally assigned +in the order they register, although if an SMI unregisters and then +another one registers, all bets are off. + +The ipmi_smi.h defines the interface for management interfaces, see +that for more details. + + +The SI Driver +------------- + +The SI driver allows KCS, BT, and SMIC interfaces to be configured +in the system. It discovers interfaces through a host of different +methods, depending on the system. + +You can specify up to four interfaces on the module load line and +control some module parameters:: + + modprobe ipmi_si.o type=<type1>,<type2>.... + ports=<port1>,<port2>... addrs=<addr1>,<addr2>... + irqs=<irq1>,<irq2>... + regspacings=<sp1>,<sp2>,... regsizes=<size1>,<size2>,... + regshifts=<shift1>,<shift2>,... + slave_addrs=<addr1>,<addr2>,... + force_kipmid=<enable1>,<enable2>,... + kipmid_max_busy_us=<ustime1>,<ustime2>,... + unload_when_empty=[0|1] + trydmi=[0|1] tryacpi=[0|1] + tryplatform=[0|1] trypci=[0|1] + +Each of these except try... items is a list, the first item for the +first interface, second item for the second interface, etc. + +The si_type may be either "kcs", "smic", or "bt". If you leave it blank, it +defaults to "kcs". + +If you specify addrs as non-zero for an interface, the driver will +use the memory address given as the address of the device. This +overrides si_ports. + +If you specify ports as non-zero for an interface, the driver will +use the I/O port given as the device address. + +If you specify irqs as non-zero for an interface, the driver will +attempt to use the given interrupt for the device. + +The other try... items disable discovery by their corresponding +names. These are all enabled by default, set them to zero to disable +them. The tryplatform disables openfirmware. + +The next three parameters have to do with register layout. The +registers used by the interfaces may not appear at successive +locations and they may not be in 8-bit registers. These parameters +allow the layout of the data in the registers to be more precisely +specified. + +The regspacings parameter give the number of bytes between successive +register start addresses. For instance, if the regspacing is set to 4 +and the start address is 0xca2, then the address for the second +register would be 0xca6. This defaults to 1. + +The regsizes parameter gives the size of a register, in bytes. The +data used by IPMI is 8-bits wide, but it may be inside a larger +register. This parameter allows the read and write type to specified. +It may be 1, 2, 4, or 8. The default is 1. + +Since the register size may be larger than 32 bits, the IPMI data may not +be in the lower 8 bits. The regshifts parameter give the amount to shift +the data to get to the actual IPMI data. + +The slave_addrs specifies the IPMI address of the local BMC. This is +usually 0x20 and the driver defaults to that, but in case it's not, it +can be specified when the driver starts up. + +The force_ipmid parameter forcefully enables (if set to 1) or disables +(if set to 0) the kernel IPMI daemon. Normally this is auto-detected +by the driver, but systems with broken interrupts might need an enable, +or users that don't want the daemon (don't need the performance, don't +want the CPU hit) can disable it. + +If unload_when_empty is set to 1, the driver will be unloaded if it +doesn't find any interfaces or all the interfaces fail to work. The +default is one. Setting to 0 is useful with the hotmod, but is +obviously only useful for modules. + +When compiled into the kernel, the parameters can be specified on the +kernel command line as:: + + ipmi_si.type=<type1>,<type2>... + ipmi_si.ports=<port1>,<port2>... ipmi_si.addrs=<addr1>,<addr2>... + ipmi_si.irqs=<irq1>,<irq2>... + ipmi_si.regspacings=<sp1>,<sp2>,... + ipmi_si.regsizes=<size1>,<size2>,... + ipmi_si.regshifts=<shift1>,<shift2>,... + ipmi_si.slave_addrs=<addr1>,<addr2>,... + ipmi_si.force_kipmid=<enable1>,<enable2>,... + ipmi_si.kipmid_max_busy_us=<ustime1>,<ustime2>,... + +It works the same as the module parameters of the same names. + +If your IPMI interface does not support interrupts and is a KCS or +SMIC interface, the IPMI driver will start a kernel thread for the +interface to help speed things up. This is a low-priority kernel +thread that constantly polls the IPMI driver while an IPMI operation +is in progress. The force_kipmid module parameter will all the user to +force this thread on or off. If you force it off and don't have +interrupts, the driver will run VERY slowly. Don't blame me, +these interfaces suck. + +Unfortunately, this thread can use a lot of CPU depending on the +interface's performance. This can waste a lot of CPU and cause +various issues with detecting idle CPU and using extra power. To +avoid this, the kipmid_max_busy_us sets the maximum amount of time, in +microseconds, that kipmid will spin before sleeping for a tick. This +value sets a balance between performance and CPU waste and needs to be +tuned to your needs. Maybe, someday, auto-tuning will be added, but +that's not a simple thing and even the auto-tuning would need to be +tuned to the user's desired performance. + +The driver supports a hot add and remove of interfaces. This way, +interfaces can be added or removed after the kernel is up and running. +This is done using /sys/modules/ipmi_si/parameters/hotmod, which is a +write-only parameter. You write a string to this interface. The string +has the format:: + + <op1>[:op2[:op3...]] + +The "op"s are:: + + add|remove,kcs|bt|smic,mem|i/o,<address>[,<opt1>[,<opt2>[,...]]] + +You can specify more than one interface on the line. The "opt"s are:: + + rsp=<regspacing> + rsi=<regsize> + rsh=<regshift> + irq=<irq> + ipmb=<ipmb slave addr> + +and these have the same meanings as discussed above. Note that you +can also use this on the kernel command line for a more compact format +for specifying an interface. Note that when removing an interface, +only the first three parameters (si type, address type, and address) +are used for the comparison. Any options are ignored for removing. + +The SMBus Driver (SSIF) +----------------------- + +The SMBus driver allows up to 4 SMBus devices to be configured in the +system. By default, the driver will only register with something it +finds in DMI or ACPI tables. You can change this +at module load time (for a module) with:: + + modprobe ipmi_ssif.o + addr=<i2caddr1>[,<i2caddr2>[,...]] + adapter=<adapter1>[,<adapter2>[...]] + dbg=<flags1>,<flags2>... + slave_addrs=<addr1>,<addr2>,... + tryacpi=[0|1] trydmi=[0|1] + [dbg_probe=1] + +The addresses are normal I2C addresses. The adapter is the string +name of the adapter, as shown in /sys/class/i2c-adapter/i2c-<n>/name. +It is *NOT* i2c-<n> itself. Also, the comparison is done ignoring +spaces, so if the name is "This is an I2C chip" you can say +adapter_name=ThisisanI2cchip. This is because it's hard to pass in +spaces in kernel parameters. + +The debug flags are bit flags for each BMC found, they are: +IPMI messages: 1, driver state: 2, timing: 4, I2C probe: 8 + +The tryxxx parameters can be used to disable detecting interfaces +from various sources. + +Setting dbg_probe to 1 will enable debugging of the probing and +detection process for BMCs on the SMBusses. + +The slave_addrs specifies the IPMI address of the local BMC. This is +usually 0x20 and the driver defaults to that, but in case it's not, it +can be specified when the driver starts up. + +Discovering the IPMI compliant BMC on the SMBus can cause devices on +the I2C bus to fail. The SMBus driver writes a "Get Device ID" IPMI +message as a block write to the I2C bus and waits for a response. +This action can be detrimental to some I2C devices. It is highly +recommended that the known I2C address be given to the SMBus driver in +the smb_addr parameter unless you have DMI or ACPI data to tell the +driver what to use. + +When compiled into the kernel, the addresses can be specified on the +kernel command line as:: + + ipmb_ssif.addr=<i2caddr1>[,<i2caddr2>[...]] + ipmi_ssif.adapter=<adapter1>[,<adapter2>[...]] + ipmi_ssif.dbg=<flags1>[,<flags2>[...]] + ipmi_ssif.dbg_probe=1 + ipmi_ssif.slave_addrs=<addr1>[,<addr2>[...]] + ipmi_ssif.tryacpi=[0|1] ipmi_ssif.trydmi=[0|1] + +These are the same options as on the module command line. + +The I2C driver does not support non-blocking access or polling, so +this driver cannod to IPMI panic events, extend the watchdog at panic +time, or other panic-related IPMI functions without special kernel +patches and driver modifications. You can get those at the openipmi +web page. + +The driver supports a hot add and remove of interfaces through the I2C +sysfs interface. + +Other Pieces +------------ + +Get the detailed info related with the IPMI device +-------------------------------------------------- + +Some users need more detailed information about a device, like where +the address came from or the raw base device for the IPMI interface. +You can use the IPMI smi_watcher to catch the IPMI interfaces as they +come or go, and to grab the information, you can use the function +ipmi_get_smi_info(), which returns the following structure:: + + struct ipmi_smi_info { + enum ipmi_addr_src addr_src; + struct device *dev; + union { + struct { + void *acpi_handle; + } acpi_info; + } addr_info; + }; + +Currently special info for only for SI_ACPI address sources is +returned. Others may be added as necessary. + +Note that the dev pointer is included in the above structure, and +assuming ipmi_smi_get_info returns success, you must call put_device +on the dev pointer. + + +Watchdog +-------- + +A watchdog timer is provided that implements the Linux-standard +watchdog timer interface. It has three module parameters that can be +used to control it:: + + modprobe ipmi_watchdog timeout=<t> pretimeout=<t> action=<action type> + preaction=<preaction type> preop=<preop type> start_now=x + nowayout=x ifnum_to_use=n panic_wdt_timeout=<t> + +ifnum_to_use specifies which interface the watchdog timer should use. +The default is -1, which means to pick the first one registered. + +The timeout is the number of seconds to the action, and the pretimeout +is the amount of seconds before the reset that the pre-timeout panic will +occur (if pretimeout is zero, then pretimeout will not be enabled). Note +that the pretimeout is the time before the final timeout. So if the +timeout is 50 seconds and the pretimeout is 10 seconds, then the pretimeout +will occur in 40 second (10 seconds before the timeout). The panic_wdt_timeout +is the value of timeout which is set on kernel panic, in order to let actions +such as kdump to occur during panic. + +The action may be "reset", "power_cycle", or "power_off", and +specifies what to do when the timer times out, and defaults to +"reset". + +The preaction may be "pre_smi" for an indication through the SMI +interface, "pre_int" for an indication through the SMI with an +interrupts, and "pre_nmi" for a NMI on a preaction. This is how +the driver is informed of the pretimeout. + +The preop may be set to "preop_none" for no operation on a pretimeout, +"preop_panic" to set the preoperation to panic, or "preop_give_data" +to provide data to read from the watchdog device when the pretimeout +occurs. A "pre_nmi" setting CANNOT be used with "preop_give_data" +because you can't do data operations from an NMI. + +When preop is set to "preop_give_data", one byte comes ready to read +on the device when the pretimeout occurs. Select and fasync work on +the device, as well. + +If start_now is set to 1, the watchdog timer will start running as +soon as the driver is loaded. + +If nowayout is set to 1, the watchdog timer will not stop when the +watchdog device is closed. The default value of nowayout is true +if the CONFIG_WATCHDOG_NOWAYOUT option is enabled, or false if not. + +When compiled into the kernel, the kernel command line is available +for configuring the watchdog:: + + ipmi_watchdog.timeout=<t> ipmi_watchdog.pretimeout=<t> + ipmi_watchdog.action=<action type> + ipmi_watchdog.preaction=<preaction type> + ipmi_watchdog.preop=<preop type> + ipmi_watchdog.start_now=x + ipmi_watchdog.nowayout=x + ipmi_watchdog.panic_wdt_timeout=<t> + +The options are the same as the module parameter options. + +The watchdog will panic and start a 120 second reset timeout if it +gets a pre-action. During a panic or a reboot, the watchdog will +start a 120 timer if it is running to make sure the reboot occurs. + +Note that if you use the NMI preaction for the watchdog, you MUST NOT +use the nmi watchdog. There is no reasonable way to tell if an NMI +comes from the IPMI controller, so it must assume that if it gets an +otherwise unhandled NMI, it must be from IPMI and it will panic +immediately. + +Once you open the watchdog timer, you must write a 'V' character to the +device to close it, or the timer will not stop. This is a new semantic +for the driver, but makes it consistent with the rest of the watchdog +drivers in Linux. + + +Panic Timeouts +-------------- + +The OpenIPMI driver supports the ability to put semi-custom and custom +events in the system event log if a panic occurs. if you enable the +'Generate a panic event to all BMCs on a panic' option, you will get +one event on a panic in a standard IPMI event format. If you enable +the 'Generate OEM events containing the panic string' option, you will +also get a bunch of OEM events holding the panic string. + + +The field settings of the events are: + +* Generator ID: 0x21 (kernel) +* EvM Rev: 0x03 (this event is formatting in IPMI 1.0 format) +* Sensor Type: 0x20 (OS critical stop sensor) +* Sensor #: The first byte of the panic string (0 if no panic string) +* Event Dir | Event Type: 0x6f (Assertion, sensor-specific event info) +* Event Data 1: 0xa1 (Runtime stop in OEM bytes 2 and 3) +* Event data 2: second byte of panic string +* Event data 3: third byte of panic string + +See the IPMI spec for the details of the event layout. This event is +always sent to the local management controller. It will handle routing +the message to the right place + +Other OEM events have the following format: + +* Record ID (bytes 0-1): Set by the SEL. +* Record type (byte 2): 0xf0 (OEM non-timestamped) +* byte 3: The slave address of the card saving the panic +* byte 4: A sequence number (starting at zero) + The rest of the bytes (11 bytes) are the panic string. If the panic string + is longer than 11 bytes, multiple messages will be sent with increasing + sequence numbers. + +Because you cannot send OEM events using the standard interface, this +function will attempt to find an SEL and add the events there. It +will first query the capabilities of the local management controller. +If it has an SEL, then they will be stored in the SEL of the local +management controller. If not, and the local management controller is +an event generator, the event receiver from the local management +controller will be queried and the events sent to the SEL on that +device. Otherwise, the events go nowhere since there is nowhere to +send them. + + +Poweroff +-------- + +If the poweroff capability is selected, the IPMI driver will install +a shutdown function into the standard poweroff function pointer. This +is in the ipmi_poweroff module. When the system requests a powerdown, +it will send the proper IPMI commands to do this. This is supported on +several platforms. + +There is a module parameter named "poweroff_powercycle" that may +either be zero (do a power down) or non-zero (do a power cycle, power +the system off, then power it on in a few seconds). Setting +ipmi_poweroff.poweroff_control=x will do the same thing on the kernel +command line. The parameter is also available via the proc filesystem +in /proc/sys/dev/ipmi/poweroff_powercycle. Note that if the system +does not support power cycling, it will always do the power off. + +The "ifnum_to_use" parameter specifies which interface the poweroff +code should use. The default is -1, which means to pick the first one +registered. + +Note that if you have ACPI enabled, the system will prefer using ACPI to +power off. diff --git a/Documentation/driver-api/nvdimm/nvdimm.rst b/Documentation/driver-api/nvdimm/nvdimm.rst index 08f855cbb4e6..79c0fd39f2af 100644 --- a/Documentation/driver-api/nvdimm/nvdimm.rst +++ b/Documentation/driver-api/nvdimm/nvdimm.rst @@ -278,8 +278,8 @@ by a region device with a dynamically assigned id (REGION0 - REGION5). be contiguous in DPA-space. This bus is provided by the kernel under the device - /sys/devices/platform/nfit_test.0 when CONFIG_NFIT_TEST is enabled and - the nfit_test.ko module is loaded. This not only test LIBNVDIMM but the + /sys/devices/platform/nfit_test.0 when the nfit_test.ko module from + tools/testing/nvdimm is loaded. This not only test LIBNVDIMM but the acpi_nfit.ko driver as well. diff --git a/Documentation/driver-api/pm/cpuidle.rst b/Documentation/driver-api/pm/cpuidle.rst index 006cf6db40c6..3588bf078566 100644 --- a/Documentation/driver-api/pm/cpuidle.rst +++ b/Documentation/driver-api/pm/cpuidle.rst @@ -68,9 +68,8 @@ only one in the list (that is, the list was empty before) or the value of its governor currently in use, or the name of the new governor was passed to the kernel as the value of the ``cpuidle.governor=`` command line parameter, the new governor will be used from that point on (there can be only one ``CPUIdle`` -governor in use at a time). Also, if ``cpuidle_sysfs_switch`` is passed to the -kernel in the command line, user space can choose the ``CPUIdle`` governor to -use at run time via ``sysfs``. +governor in use at a time). Also, user space can choose the ``CPUIdle`` +governor to use at run time via ``sysfs``. Once registered, ``CPUIdle`` governors cannot be unregistered, so it is not practical to put them into loadable kernel modules. diff --git a/Documentation/driver-api/pm/devices.rst b/Documentation/driver-api/pm/devices.rst index f66c7b9126ea..946ad0b94e31 100644 --- a/Documentation/driver-api/pm/devices.rst +++ b/Documentation/driver-api/pm/devices.rst @@ -349,7 +349,7 @@ the phases are: ``prepare``, ``suspend``, ``suspend_late``, ``suspend_noirq``. PM core will skip the ``suspend``, ``suspend_late`` and ``suspend_noirq`` phases as well as all of the corresponding phases of the subsequent device resume for all of these devices. In that case, - the ``->complete`` callback will be invoked directly after the + the ``->complete`` callback will be the next one invoked after the ``->prepare`` callback and is entirely responsible for putting the device into a consistent state as appropriate. @@ -361,9 +361,9 @@ the phases are: ``prepare``, ``suspend``, ``suspend_late``, ``suspend_noirq``. runtime PM disabled. This feature also can be controlled by device drivers by using the - ``DPM_FLAG_NEVER_SKIP`` and ``DPM_FLAG_SMART_PREPARE`` driver power - management flags. [Typically, they are set at the time the driver is - probed against the device in question by passing them to the + ``DPM_FLAG_NO_DIRECT_COMPLETE`` and ``DPM_FLAG_SMART_PREPARE`` driver + power management flags. [Typically, they are set at the time the driver + is probed against the device in question by passing them to the :c:func:`dev_pm_set_driver_flags` helper function.] If the first of these flags is set, the PM core will not apply the direct-complete procedure described above to the given device and, consequenty, to any @@ -383,11 +383,15 @@ the phases are: ``prepare``, ``suspend``, ``suspend_late``, ``suspend_noirq``. ``->suspend`` methods provided by subsystems (bus types and PM domains in particular) must follow an additional rule regarding what can be done to the devices before their drivers' ``->suspend`` methods are called. - Namely, they can only resume the devices from runtime suspend by - calling :c:func:`pm_runtime_resume` for them, if that is necessary, and + Namely, they may resume the devices from runtime suspend by + calling :c:func:`pm_runtime_resume` for them, if that is necessary, but they must not update the state of the devices in any other way at that time (in case the drivers need to resume the devices from runtime - suspend in their ``->suspend`` methods). + suspend in their ``->suspend`` methods). In fact, the PM core prevents + subsystems or drivers from putting devices into runtime suspend at + these times by calling :c:func:`pm_runtime_get_noresume` before issuing + the ``->prepare`` callback (and calling :c:func:`pm_runtime_put` after + issuing the ``->complete`` callback). 3. For a number of devices it is convenient to split suspend into the "quiesce device" and "save device state" phases, in which cases @@ -459,22 +463,22 @@ When resuming from freeze, standby or memory sleep, the phases are: Note, however, that new children may be registered below the device as soon as the ``->resume`` callbacks occur; it's not necessary to wait - until the ``complete`` phase with that. + until the ``complete`` phase runs. Moreover, if the preceding ``->prepare`` callback returned a positive number, the device may have been left in runtime suspend throughout the - whole system suspend and resume (the ``suspend``, ``suspend_late``, - ``suspend_noirq`` phases of system suspend and the ``resume_noirq``, - ``resume_early``, ``resume`` phases of system resume may have been - skipped for it). In that case, the ``->complete`` callback is entirely + whole system suspend and resume (its ``->suspend``, ``->suspend_late``, + ``->suspend_noirq``, ``->resume_noirq``, + ``->resume_early``, and ``->resume`` callbacks may have been + skipped). In that case, the ``->complete`` callback is entirely responsible for putting the device into a consistent state after system suspend if necessary. [For example, it may need to queue up a runtime resume request for the device for this purpose.] To check if that is the case, the ``->complete`` callback can consult the device's - ``power.direct_complete`` flag. Namely, if that flag is set when the - ``->complete`` callback is being run, it has been called directly after - the preceding ``->prepare`` and special actions may be required - to make the device work correctly afterward. + ``power.direct_complete`` flag. If that flag is set when the + ``->complete`` callback is being run then the direct-complete mechanism + was used, and special actions may be required to make the device work + correctly afterward. At the end of these phases, drivers should be as functional as they were before suspending: I/O can be performed using DMA and IRQs, and the relevant clocks are @@ -575,10 +579,12 @@ and the phases are similar. The ``->poweroff``, ``->poweroff_late`` and ``->poweroff_noirq`` callbacks should do essentially the same things as the ``->suspend``, ``->suspend_late`` -and ``->suspend_noirq`` callbacks, respectively. The only notable difference is +and ``->suspend_noirq`` callbacks, respectively. A notable difference is that they need not store the device register values, because the registers should already have been stored during the ``freeze``, ``freeze_late`` or -``freeze_noirq`` phases. +``freeze_noirq`` phases. Also, on many machines the firmware will power-down +the entire system, so it is not necessary for the callback to put the device in +a low-power state. Leaving Hibernation @@ -764,70 +770,119 @@ device driver in question. If it is necessary to resume a device from runtime suspend during a system-wide transition into a sleep state, that can be done by calling -:c:func:`pm_runtime_resume` for it from the ``->suspend`` callback (or its -couterpart for transitions related to hibernation) of either the device's driver -or a subsystem responsible for it (for example, a bus type or a PM domain). -That is guaranteed to work by the requirement that subsystems must not change -the state of devices (possibly except for resuming them from runtime suspend) +:c:func:`pm_runtime_resume` from the ``->suspend`` callback (or the ``->freeze`` +or ``->poweroff`` callback for transitions related to hibernation) of either the +device's driver or its subsystem (for example, a bus type or a PM domain). +However, subsystems must not otherwise change the runtime status of devices from their ``->prepare`` and ``->suspend`` callbacks (or equivalent) *before* invoking device drivers' ``->suspend`` callbacks (or equivalent). +.. _smart_suspend_flag: + +The ``DPM_FLAG_SMART_SUSPEND`` Driver Flag +------------------------------------------ + Some bus types and PM domains have a policy to resume all devices from runtime suspend upfront in their ``->suspend`` callbacks, but that may not be really -necessary if the driver of the device can cope with runtime-suspended devices. -The driver can indicate that by setting ``DPM_FLAG_SMART_SUSPEND`` in -:c:member:`power.driver_flags` at the probe time, by passing it to the -:c:func:`dev_pm_set_driver_flags` helper. That also may cause middle-layer code +necessary if the device's driver can cope with runtime-suspended devices. +The driver can indicate this by setting ``DPM_FLAG_SMART_SUSPEND`` in +:c:member:`power.driver_flags` at probe time, with the assistance of the +:c:func:`dev_pm_set_driver_flags` helper routine. + +Setting that flag causes the PM core and middle-layer code (bus types, PM domains etc.) to skip the ``->suspend_late`` and ``->suspend_noirq`` callbacks provided by the driver if the device remains in -runtime suspend at the beginning of the ``suspend_late`` phase of system-wide -suspend (or in the ``poweroff_late`` phase of hibernation), when runtime PM -has been disabled for it, under the assumption that its state should not change -after that point until the system-wide transition is over (the PM core itself -does that for devices whose "noirq", "late" and "early" system-wide PM callbacks -are executed directly by it). If that happens, the driver's system-wide resume -callbacks, if present, may still be invoked during the subsequent system-wide -resume transition and the device's runtime power management status may be set -to "active" before enabling runtime PM for it, so the driver must be prepared to -cope with the invocation of its system-wide resume callbacks back-to-back with -its ``->runtime_suspend`` one (without the intervening ``->runtime_resume`` and -so on) and the final state of the device must reflect the "active" runtime PM -status in that case. +runtime suspend throughout those phases of the system-wide suspend (and +similarly for the "freeze" and "poweroff" parts of system hibernation). +[Otherwise the same driver +callback might be executed twice in a row for the same device, which would not +be valid in general.] If the middle-layer system-wide PM callbacks are present +for the device then they are responsible for skipping these driver callbacks; +if not then the PM core skips them. The subsystem callback routines can +determine whether they need to skip the driver callbacks by testing the return +value from the :c:func:`dev_pm_skip_suspend` helper function. + +In addition, with ``DPM_FLAG_SMART_SUSPEND`` set, the driver's ``->thaw_noirq`` +and ``->thaw_early`` callbacks are skipped in hibernation if the device remained +in runtime suspend throughout the preceding "freeze" transition. Again, if the +middle-layer callbacks are present for the device, they are responsible for +doing this, otherwise the PM core takes care of it. + + +The ``DPM_FLAG_MAY_SKIP_RESUME`` Driver Flag +-------------------------------------------- During system-wide resume from a sleep state it's easiest to put devices into the full-power state, as explained in :file:`Documentation/power/runtime_pm.rst`. [Refer to that document for more information regarding this particular issue as well as for information on the device runtime power management framework in -general.] - -However, it often is desirable to leave devices in suspend after system -transitions to the working state, especially if those devices had been in +general.] However, it often is desirable to leave devices in suspend after +system transitions to the working state, especially if those devices had been in runtime suspend before the preceding system-wide suspend (or analogous) -transition. Device drivers can use the ``DPM_FLAG_LEAVE_SUSPENDED`` flag to -indicate to the PM core (and middle-layer code) that they prefer the specific -devices handled by them to be left suspended and they have no problems with -skipping their system-wide resume callbacks for this reason. Whether or not the -devices will actually be left in suspend may depend on their state before the -given system suspend-resume cycle and on the type of the system transition under -way. In particular, devices are not left suspended if that transition is a -restore from hibernation, as device states are not guaranteed to be reflected -by the information stored in the hibernation image in that case. - -The middle-layer code involved in the handling of the device is expected to -indicate to the PM core if the device may be left in suspend by setting its -:c:member:`power.may_skip_resume` status bit which is checked by the PM core -during the "noirq" phase of the preceding system-wide suspend (or analogous) -transition. The middle layer is then responsible for handling the device as -appropriate in its "noirq" resume callback, which is executed regardless of -whether or not the device is left suspended, but the other resume callbacks -(except for ``->complete``) will be skipped automatically by the PM core if the -device really can be left in suspend. - -For devices whose "noirq", "late" and "early" driver callbacks are invoked -directly by the PM core, all of the system-wide resume callbacks are skipped if -``DPM_FLAG_LEAVE_SUSPENDED`` is set and the device is in runtime suspend during -the ``suspend_noirq`` (or analogous) phase or the transition under way is a -proper system suspend (rather than anything related to hibernation) and the -device's wakeup settings are suitable for runtime PM (that is, it cannot -generate wakeup signals at all or it is allowed to wake up the system from -sleep). +transition. + +To that end, device drivers can use the ``DPM_FLAG_MAY_SKIP_RESUME`` flag to +indicate to the PM core and middle-layer code that they allow their "noirq" and +"early" resume callbacks to be skipped if the device can be left in suspend +after system-wide PM transitions to the working state. Whether or not that is +the case generally depends on the state of the device before the given system +suspend-resume cycle and on the type of the system transition under way. +In particular, the "thaw" and "restore" transitions related to hibernation are +not affected by ``DPM_FLAG_MAY_SKIP_RESUME`` at all. [All callbacks are +issued during the "restore" transition regardless of the flag settings, +and whether or not any driver callbacks +are skipped during the "thaw" transition depends whether or not the +``DPM_FLAG_SMART_SUSPEND`` flag is set (see `above <smart_suspend_flag_>`_). +In addition, a device is not allowed to remain in runtime suspend if any of its +children will be returned to full power.] + +The ``DPM_FLAG_MAY_SKIP_RESUME`` flag is taken into account in combination with +the :c:member:`power.may_skip_resume` status bit set by the PM core during the +"suspend" phase of suspend-type transitions. If the driver or the middle layer +has a reason to prevent the driver's "noirq" and "early" resume callbacks from +being skipped during the subsequent system resume transition, it should +clear :c:member:`power.may_skip_resume` in its ``->suspend``, ``->suspend_late`` +or ``->suspend_noirq`` callback. [Note that the drivers setting +``DPM_FLAG_SMART_SUSPEND`` need to clear :c:member:`power.may_skip_resume` in +their ``->suspend`` callback in case the other two are skipped.] + +Setting the :c:member:`power.may_skip_resume` status bit along with the +``DPM_FLAG_MAY_SKIP_RESUME`` flag is necessary, but generally not sufficient, +for the driver's "noirq" and "early" resume callbacks to be skipped. Whether or +not they should be skipped can be determined by evaluating the +:c:func:`dev_pm_skip_resume` helper function. + +If that function returns ``true``, the driver's "noirq" and "early" resume +callbacks should be skipped and the device's runtime PM status will be set to +"suspended" by the PM core. Otherwise, if the device was runtime-suspended +during the preceding system-wide suspend transition and its +``DPM_FLAG_SMART_SUSPEND`` is set, its runtime PM status will be set to +"active" by the PM core. [Hence, the drivers that do not set +``DPM_FLAG_SMART_SUSPEND`` should not expect the runtime PM status of their +devices to be changed from "suspended" to "active" by the PM core during +system-wide resume-type transitions.] + +If the ``DPM_FLAG_MAY_SKIP_RESUME`` flag is not set for a device, but +``DPM_FLAG_SMART_SUSPEND`` is set and the driver's "late" and "noirq" suspend +callbacks are skipped, its system-wide "noirq" and "early" resume callbacks, if +present, are invoked as usual and the device's runtime PM status is set to +"active" by the PM core before enabling runtime PM for it. In that case, the +driver must be prepared to cope with the invocation of its system-wide resume +callbacks back-to-back with its ``->runtime_suspend`` one (without the +intervening ``->runtime_resume`` and system-wide suspend callbacks) and the +final state of the device must reflect the "active" runtime PM status in that +case. [Note that this is not a problem at all if the driver's +``->suspend_late`` callback pointer points to the same function as its +``->runtime_suspend`` one and its ``->resume_early`` callback pointer points to +the same function as the ``->runtime_resume`` one, while none of the other +system-wide suspend-resume callbacks of the driver are present, for example.] + +Likewise, if ``DPM_FLAG_MAY_SKIP_RESUME`` is set for a device, its driver's +system-wide "noirq" and "early" resume callbacks may be skipped while its "late" +and "noirq" suspend callbacks may have been executed (in principle, regardless +of whether or not ``DPM_FLAG_SMART_SUSPEND`` is set). In that case, the driver +needs to be able to cope with the invocation of its ``->runtime_resume`` +callback back-to-back with its "late" and "noirq" suspend ones. [For instance, +that is not a concern if the driver sets both ``DPM_FLAG_SMART_SUSPEND`` and +``DPM_FLAG_MAY_SKIP_RESUME`` and uses the same pair of suspend/resume callback +functions for runtime PM and system-wide suspend/resume.] diff --git a/Documentation/driver-api/thermal/cpu-idle-cooling.rst b/Documentation/driver-api/thermal/cpu-idle-cooling.rst index a1c3edecae00..b9f34ceb2a38 100644 --- a/Documentation/driver-api/thermal/cpu-idle-cooling.rst +++ b/Documentation/driver-api/thermal/cpu-idle-cooling.rst @@ -1,3 +1,6 @@ +================ +CPU Idle Cooling +================ Situation: ---------- diff --git a/Documentation/driver-api/thermal/index.rst b/Documentation/driver-api/thermal/index.rst index 5ba61d19c6ae..4cb0b9b6bfb8 100644 --- a/Documentation/driver-api/thermal/index.rst +++ b/Documentation/driver-api/thermal/index.rst @@ -8,6 +8,7 @@ Thermal :maxdepth: 1 cpu-cooling-api + cpu-idle-cooling sysfs-api power_allocator |