diff options
Diffstat (limited to 'Documentation')
| -rw-r--r-- | Documentation/Smack.txt | 493 | ||||
| -rw-r--r-- | Documentation/filesystems/proc.txt | 95 | ||||
| -rw-r--r-- | Documentation/gpio.txt | 133 | ||||
| -rw-r--r-- | Documentation/i2c/chips/pca9539 | 3 | ||||
| -rw-r--r-- | Documentation/pcmcia/driver-changes.txt | 4 | ||||
| -rw-r--r-- | Documentation/pm_qos_interface.txt | 59 | ||||
| -rw-r--r-- | Documentation/sysctl/vm.txt | 7 |
7 files changed, 760 insertions, 34 deletions
diff --git a/Documentation/Smack.txt b/Documentation/Smack.txt new file mode 100644 index 000000000000..989c2fcd8111 --- /dev/null +++ b/Documentation/Smack.txt @@ -0,0 +1,493 @@ + + + "Good for you, you've decided to clean the elevator!" + - The Elevator, from Dark Star + +Smack is the the Simplified Mandatory Access Control Kernel. +Smack is a kernel based implementation of mandatory access +control that includes simplicity in its primary design goals. + +Smack is not the only Mandatory Access Control scheme +available for Linux. Those new to Mandatory Access Control +are encouraged to compare Smack with the other mechanisms +available to determine which is best suited to the problem +at hand. + +Smack consists of three major components: + - The kernel + - A start-up script and a few modified applications + - Configuration data + +The kernel component of Smack is implemented as a Linux +Security Modules (LSM) module. It requires netlabel and +works best with file systems that support extended attributes, +although xattr support is not strictly required. +It is safe to run a Smack kernel under a "vanilla" distribution. +Smack kernels use the CIPSO IP option. Some network +configurations are intolerant of IP options and can impede +access to systems that use them as Smack does. + +The startup script etc-init.d-smack should be installed +in /etc/init.d/smack and should be invoked early in the +start-up process. On Fedora rc5.d/S02smack is recommended. +This script ensures that certain devices have the correct +Smack attributes and loads the Smack configuration if +any is defined. This script invokes two programs that +ensure configuration data is properly formatted. These +programs are /usr/sbin/smackload and /usr/sin/smackcipso. +The system will run just fine without these programs, +but it will be difficult to set access rules properly. + +A version of "ls" that provides a "-M" option to display +Smack labels on long listing is available. + +A hacked version of sshd that allows network logins by users +with specific Smack labels is available. This version does +not work for scp. You must set the /etc/ssh/sshd_config +line: + UsePrivilegeSeparation no + +The format of /etc/smack/usr is: + + username smack + +In keeping with the intent of Smack, configuration data is +minimal and not strictly required. The most important +configuration step is mounting the smackfs pseudo filesystem. + +Add this line to /etc/fstab: + + smackfs /smack smackfs smackfsdef=* 0 0 + +and create the /smack directory for mounting. + +Smack uses extended attributes (xattrs) to store file labels. +The command to set a Smack label on a file is: + + # attr -S -s SMACK64 -V "value" path + +NOTE: Smack labels are limited to 23 characters. The attr command + does not enforce this restriction and can be used to set + invalid Smack labels on files. + +If you don't do anything special all users will get the floor ("_") +label when they log in. If you do want to log in via the hacked ssh +at other labels use the attr command to set the smack value on the +home directory and it's contents. + +You can add access rules in /etc/smack/accesses. They take the form: + + subjectlabel objectlabel access + +access is a combination of the letters rwxa which specify the +kind of access permitted a subject with subjectlabel on an +object with objectlabel. If there is no rule no access is allowed. + +A process can see the smack label it is running with by +reading /proc/self/attr/current. A privileged process can +set the process smack by writing there. + +Look for additional programs on http://schaufler-ca.com + +From the Smack Whitepaper: + +The Simplified Mandatory Access Control Kernel + +Casey Schaufler +casey@schaufler-ca.com + +Mandatory Access Control + +Computer systems employ a variety of schemes to constrain how information is +shared among the people and services using the machine. Some of these schemes +allow the program or user to decide what other programs or users are allowed +access to pieces of data. These schemes are called discretionary access +control mechanisms because the access control is specified at the discretion +of the user. Other schemes do not leave the decision regarding what a user or +program can access up to users or programs. These schemes are called mandatory +access control mechanisms because you don't have a choice regarding the users +or programs that have access to pieces of data. + +Bell & LaPadula + +From the middle of the 1980's until the turn of the century Mandatory Access +Control (MAC) was very closely associated with the Bell & LaPadula security +model, a mathematical description of the United States Department of Defense +policy for marking paper documents. MAC in this form enjoyed a following +within the Capital Beltway and Scandinavian supercomputer centers but was +often sited as failing to address general needs. + +Domain Type Enforcement + +Around the turn of the century Domain Type Enforcement (DTE) became popular. +This scheme organizes users, programs, and data into domains that are +protected from each other. This scheme has been widely deployed as a component +of popular Linux distributions. The administrative overhead required to +maintain this scheme and the detailed understanding of the whole system +necessary to provide a secure domain mapping leads to the scheme being +disabled or used in limited ways in the majority of cases. + +Smack + +Smack is a Mandatory Access Control mechanism designed to provide useful MAC +while avoiding the pitfalls of its predecessors. The limitations of Bell & +LaPadula are addressed by providing a scheme whereby access can be controlled +according to the requirements of the system and its purpose rather than those +imposed by an arcane government policy. The complexity of Domain Type +Enforcement and avoided by defining access controls in terms of the access +modes already in use. + +Smack Terminology + +The jargon used to talk about Smack will be familiar to those who have dealt +with other MAC systems and shouldn't be too difficult for the uninitiated to +pick up. There are four terms that are used in a specific way and that are +especially important: + + Subject: A subject is an active entity on the computer system. + On Smack a subject is a task, which is in turn the basic unit + of execution. + + Object: An object is a passive entity on the computer system. + On Smack files of all types, IPC, and tasks can be objects. + + Access: Any attempt by a subject to put information into or get + information from an object is an access. + + Label: Data that identifies the Mandatory Access Control + characteristics of a subject or an object. + +These definitions are consistent with the traditional use in the security +community. There are also some terms from Linux that are likely to crop up: + + Capability: A task that possesses a capability has permission to + violate an aspect of the system security policy, as identified by + the specific capability. A task that possesses one or more + capabilities is a privileged task, whereas a task with no + capabilities is an unprivileged task. + + Privilege: A task that is allowed to violate the system security + policy is said to have privilege. As of this writing a task can + have privilege either by possessing capabilities or by having an + effective user of root. + +Smack Basics + +Smack is an extension to a Linux system. It enforces additional restrictions +on what subjects can access which objects, based on the labels attached to +each of the subject and the object. + +Labels + +Smack labels are ASCII character strings, one to twenty-three characters in +length. Single character labels using special characters, that being anything +other than a letter or digit, are reserved for use by the Smack development +team. Smack labels are unstructured, case sensitive, and the only operation +ever performed on them is comparison for equality. Smack labels cannot +contain unprintable characters or the "/" (slash) character. + +There are some predefined labels: + + _ Pronounced "floor", a single underscore character. + ^ Pronounced "hat", a single circumflex character. + * Pronounced "star", a single asterisk character. + ? Pronounced "huh", a single question mark character. + +Every task on a Smack system is assigned a label. System tasks, such as +init(8) and systems daemons, are run with the floor ("_") label. User tasks +are assigned labels according to the specification found in the +/etc/smack/user configuration file. + +Access Rules + +Smack uses the traditional access modes of Linux. These modes are read, +execute, write, and occasionally append. There are a few cases where the +access mode may not be obvious. These include: + + Signals: A signal is a write operation from the subject task to + the object task. + Internet Domain IPC: Transmission of a packet is considered a + write operation from the source task to the destination task. + +Smack restricts access based on the label attached to a subject and the label +attached to the object it is trying to access. The rules enforced are, in +order: + + 1. Any access requested by a task labeled "*" is denied. + 2. A read or execute access requested by a task labeled "^" + is permitted. + 3. A read or execute access requested on an object labeled "_" + is permitted. + 4. Any access requested on an object labeled "*" is permitted. + 5. Any access requested by a task on an object with the same + label is permitted. + 6. Any access requested that is explicitly defined in the loaded + rule set is permitted. + 7. Any other access is denied. + +Smack Access Rules + +With the isolation provided by Smack access separation is simple. There are +many interesting cases where limited access by subjects to objects with +different labels is desired. One example is the familiar spy model of +sensitivity, where a scientist working on a highly classified project would be +able to read documents of lower classifications and anything she writes will +be "born" highly classified. To accommodate such schemes Smack includes a +mechanism for specifying rules allowing access between labels. + +Access Rule Format + +The format of an access rule is: + + subject-label object-label access + +Where subject-label is the Smack label of the task, object-label is the Smack +label of the thing being accessed, and access is a string specifying the sort +of access allowed. The Smack labels are limited to 23 characters. The access +specification is searched for letters that describe access modes: + + a: indicates that append access should be granted. + r: indicates that read access should be granted. + w: indicates that write access should be granted. + x: indicates that execute access should be granted. + +Uppercase values for the specification letters are allowed as well. +Access mode specifications can be in any order. Examples of acceptable rules +are: + + TopSecret Secret rx + Secret Unclass R + Manager Game x + User HR w + New Old rRrRr + Closed Off - + +Examples of unacceptable rules are: + + Top Secret Secret rx + Ace Ace r + Odd spells waxbeans + +Spaces are not allowed in labels. Since a subject always has access to files +with the same label specifying a rule for that case is pointless. Only +valid letters (rwxaRWXA) and the dash ('-') character are allowed in +access specifications. The dash is a placeholder, so "a-r" is the same +as "ar". A lone dash is used to specify that no access should be allowed. + +Applying Access Rules + +The developers of Linux rarely define new sorts of things, usually importing +schemes and concepts from other systems. Most often, the other systems are +variants of Unix. Unix has many endearing properties, but consistency of +access control models is not one of them. Smack strives to treat accesses as +uniformly as is sensible while keeping with the spirit of the underlying +mechanism. + +File system objects including files, directories, named pipes, symbolic links, +and devices require access permissions that closely match those used by mode +bit access. To open a file for reading read access is required on the file. To +search a directory requires execute access. Creating a file with write access +requires both read and write access on the containing directory. Deleting a +file requires read and write access to the file and to the containing +directory. It is possible that a user may be able to see that a file exists +but not any of its attributes by the circumstance of having read access to the +containing directory but not to the differently labeled file. This is an +artifact of the file name being data in the directory, not a part of the file. + +IPC objects, message queues, semaphore sets, and memory segments exist in flat +namespaces and access requests are only required to match the object in +question. + +Process objects reflect tasks on the system and the Smack label used to access +them is the same Smack label that the task would use for its own access +attempts. Sending a signal via the kill() system call is a write operation +from the signaler to the recipient. Debugging a process requires both reading +and writing. Creating a new task is an internal operation that results in two +tasks with identical Smack labels and requires no access checks. + +Sockets are data structures attached to processes and sending a packet from +one process to another requires that the sender have write access to the +receiver. The receiver is not required to have read access to the sender. + +Setting Access Rules + +The configuration file /etc/smack/accesses contains the rules to be set at +system startup. The contents are written to the special file /smack/load. +Rules can be written to /smack/load at any time and take effect immediately. +For any pair of subject and object labels there can be only one rule, with the +most recently specified overriding any earlier specification. + +The program smackload is provided to ensure data is formatted +properly when written to /smack/load. This program reads lines +of the form + + subjectlabel objectlabel mode. + +Task Attribute + +The Smack label of a process can be read from /proc/<pid>/attr/current. A +process can read its own Smack label from /proc/self/attr/current. A +privileged process can change its own Smack label by writing to +/proc/self/attr/current but not the label of another process. + +File Attribute + +The Smack label of a filesystem object is stored as an extended attribute +named SMACK64 on the file. This attribute is in the security namespace. It can +only be changed by a process with privilege. + +Privilege + +A process with CAP_MAC_OVERRIDE is privileged. + +Smack Networking + +As mentioned before, Smack enforces access control on network protocol +transmissions. Every packet sent by a Smack process is tagged with its Smack +label. This is done by adding a CIPSO tag to the header of the IP packet. Each +packet received is expected to have a CIPSO tag that identifies the label and +if it lacks such a tag the network ambient label is assumed. Before the packet +is delivered a check is made to determine that a subject with the label on the +packet has write access to the receiving process and if that is not the case +the packet is dropped. + +CIPSO Configuration + +It is normally unnecessary to specify the CIPSO configuration. The default +values used by the system handle all internal cases. Smack will compose CIPSO +label values to match the Smack labels being used without administrative +intervention. Unlabeled packets that come into the system will be given the +ambient label. + +Smack requires configuration in the case where packets from a system that is +not smack that speaks CIPSO may be encountered. Usually this will be a Trusted +Solaris system, but there are other, less widely deployed systems out there. +CIPSO provides 3 important values, a Domain Of Interpretation (DOI), a level, +and a category set with each packet. The DOI is intended to identify a group +of systems that use compatible labeling schemes, and the DOI specified on the +smack system must match that of the remote system or packets will be +discarded. The DOI is 3 by default. The value can be read from /smack/doi and +can be changed by writing to /smack/doi. + +The label and category set are mapped to a Smack label as defined in +/etc/smack/cipso. + +A Smack/CIPSO mapping has the form: + + smack level [category [category]*] + +Smack does not expect the level or category sets to be related in any +particular way and does not assume or assign accesses based on them. Some +examples of mappings: + + TopSecret 7 + TS:A,B 7 1 2 + SecBDE 5 2 4 6 + RAFTERS 7 12 26 + +The ":" and "," characters are permitted in a Smack label but have no special +meaning. + +The mapping of Smack labels to CIPSO values is defined by writing to +/smack/cipso. Again, the format of data written to this special file +is highly restrictive, so the program smackcipso is provided to +ensure the writes are done properly. This program takes mappings +on the standard input and sends them to /smack/cipso properly. + +In addition to explicit mappings Smack supports direct CIPSO mappings. One +CIPSO level is used to indicate that the category set passed in the packet is +in fact an encoding of the Smack label. The level used is 250 by default. The +value can be read from /smack/direct and changed by writing to /smack/direct. + +Socket Attributes + +There are two attributes that are associated with sockets. These attributes +can only be set by privileged tasks, but any task can read them for their own +sockets. + + SMACK64IPIN: The Smack label of the task object. A privileged + program that will enforce policy may set this to the star label. + + SMACK64IPOUT: The Smack label transmitted with outgoing packets. + A privileged program may set this to match the label of another + task with which it hopes to communicate. + +Writing Applications for Smack + +There are three sorts of applications that will run on a Smack system. How an +application interacts with Smack will determine what it will have to do to +work properly under Smack. + +Smack Ignorant Applications + +By far the majority of applications have no reason whatever to care about the +unique properties of Smack. Since invoking a program has no impact on the +Smack label associated with the process the only concern likely to arise is +whether the process has execute access to the program. + +Smack Relevant Applications + +Some programs can be improved by teaching them about Smack, but do not make +any security decisions themselves. The utility ls(1) is one example of such a +program. + +Smack Enforcing Applications + +These are special programs that not only know about Smack, but participate in +the enforcement of system policy. In most cases these are the programs that +set up user sessions. There are also network services that provide information +to processes running with various labels. + +File System Interfaces + +Smack maintains labels on file system objects using extended attributes. The +Smack label of a file, directory, or other file system object can be obtained +using getxattr(2). + + len = getxattr("/", "security.SMACK64", value, sizeof (value)); + +will put the Smack label of the root directory into value. A privileged +process can set the Smack label of a file system object with setxattr(2). + + len = strlen("Rubble"); + rc = setxattr("/foo", "security.SMACK64", "Rubble", len, 0); + +will set the Smack label of /foo to "Rubble" if the program has appropriate +privilege. + +Socket Interfaces + +The socket attributes can be read using fgetxattr(2). + +A privileged process can set the Smack label of outgoing packets with +fsetxattr(2). + + len = strlen("Rubble"); + rc = fsetxattr(fd, "security.SMACK64IPOUT", "Rubble", len, 0); + +will set the Smack label "Rubble" on packets going out from the socket if the +program has appropriate privilege. + + rc = fsetxattr(fd, "security.SMACK64IPIN, "*", strlen("*"), 0); + +will set the Smack label "*" as the object label against which incoming +packets will be checked if the program has appropriate privilege. + +Administration + +Smack supports some mount options: + + smackfsdef=label: specifies the label to give files that lack + the Smack label extended attribute. + + smackfsroot=label: specifies the label to assign the root of the + file system if it lacks the Smack extended attribute. + + smackfshat=label: specifies a label that must have read access to + all labels set on the filesystem. Not yet enforced. + + smackfsfloor=label: specifies a label to which all labels set on the + filesystem must have read access. Not yet enforced. + +These mount options apply to all file system types. + diff --git a/Documentation/filesystems/proc.txt b/Documentation/filesystems/proc.txt index 0b1b0c008613..e2799b5fafea 100644 --- a/Documentation/filesystems/proc.txt +++ b/Documentation/filesystems/proc.txt @@ -1315,13 +1315,28 @@ for writeout by the pdflush daemons. It is expressed in 100'ths of a second. Data which has been dirty in-memory for longer than this interval will be written out next time a pdflush daemon wakes up. +highmem_is_dirtyable +-------------------- + +Only present if CONFIG_HIGHMEM is set. + +This defaults to 0 (false), meaning that the ratios set above are calculated +as a percentage of lowmem only. This protects against excessive scanning +in page reclaim, swapping and general VM distress. + +Setting this to 1 can be useful on 32 bit machines where you want to make +random changes within an MMAPed file that is larger than your available +lowmem without causing large quantities of random IO. Is is safe if the +behavior of all programs running on the machine is known and memory will +not be otherwise stressed. + legacy_va_layout ---------------- If non-zero, this sysctl disables the new 32-bit mmap mmap layout - the kernel will use the legacy (2.4) layout for all processes. -lower_zone_protection +lowmem_reserve_ratio --------------------- For some specialised workloads on highmem machines it is dangerous for @@ -1341,25 +1356,71 @@ captured into pinned user memory. mechanism will also defend that region from allocations which could use highmem or lowmem). -The `lower_zone_protection' tunable determines how aggressive the kernel is -in defending these lower zones. The default value is zero - no -protection at all. +The `lowmem_reserve_ratio' tunable determines how aggressive the kernel is +in defending these lower zones. If you have a machine which uses highmem or ISA DMA and your applications are using mlock(), or if you are running with no swap then -you probably should increase the lower_zone_protection setting. - -The units of this tunable are fairly vague. It is approximately equal -to "megabytes," so setting lower_zone_protection=100 will protect around 100 -megabytes of the lowmem zone from user allocations. It will also make -those 100 megabytes unavailable for use by applications and by -pagecache, so there is a cost. - -The effects of this tunable may be observed by monitoring -/proc/meminfo:LowFree. Write a single huge file and observe the point -at which LowFree ceases to fall. - -A reasonable value for lower_zone_protection is 100. +you probably should change the lowmem_reserve_ratio setting. + +The lowmem_reserve_ratio is an array. You can see them by reading this file. +- +% cat /proc/sys/vm/lowmem_reserve_ratio +256 256 32 +- +Note: # of this elements is one fewer than number of zones. Because the highest + zone's value is not necessary for following calculation. + +But, these values are not used directly. The kernel calculates # of protection +pages for each zones from them. These are shown as array of protection pages +in /proc/zoneinfo like followings. (This is an example of x86-64 box). +Each zone has an array of protection pages like this. + +- +Node 0, zone DMA + pages free 1355 + min 3 + low 3 + high 4 + : + : + numa_other 0 + protection: (0, 2004, 2004, 2004) + ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ + pagesets + cpu: 0 pcp: 0 + : +- +These protections are added to score to judge whether this zone should be used +for page allocation or should be reclaimed. + +In this example, if normal pages (index=2) are required to this DMA zone and +pages_high is used for watermark, the kernel judges this zone should not be +used because pages_free(1355) is smaller than watermark + protection[2] +(4 + 2004 = 2008). If this protection value is 0, this zone would be used for +normal page requirement. If requirement is DMA zone(index=0), protection[0] +(=0) is used. + +zone[i]'s protection[j] is calculated by following exprssion. + +(i < j): + zone[i]->protection[j] + = (total sums of present_pages from zone[i+1] to zone[j] on the node) + / lowmem_reserve_ratio[i]; +(i = j): + (should not be protected. = 0; +(i > j): + (not necessary, but looks 0) + +The default values of lowmem_reserve_ratio[i] are + 256 (if zone[i] means DMA or DMA32 zone) + 32 (others). +As above expression, they are reciprocal number of ratio. +256 means 1/256. # of protection pages becomes about "0.39%" of total present +pages of higher zones on the node. + +If you would like to protect more pages, smaller values are effective. +The minimum value is 1 (1/1 -> 100%). page-cluster ------------ diff --git a/Documentation/gpio.txt b/Documentation/gpio.txt index 6bc2ba215df9..8da724e2a0ff 100644 --- a/Documentation/gpio.txt +++ b/Documentation/gpio.txt @@ -32,7 +32,7 @@ The exact capabilities of GPIOs vary between systems. Common options: - Input values are likewise readable (1, 0). Some chips support readback of pins configured as "output", which is very useful in such "wire-OR" cases (to support bidirectional signaling). GPIO controllers may have - input de-glitch logic, sometimes with software controls. + input de-glitch/debounce logic, sometimes with software controls. - Inputs can often be used as IRQ signals, often edge triggered but sometimes level triggered. Such IRQs may be configurable as system @@ -60,10 +60,13 @@ used on a board that's wired differently. Only least-common-denominator functionality can be very portable. Other features are platform-specific, and that can be critical for glue logic. -Plus, this doesn't define an implementation framework, just an interface. +Plus, this doesn't require any implementation framework, just an interface. One platform might implement it as simple inline functions accessing chip registers; another might implement it by delegating through abstractions -used for several very different kinds of GPIO controller. +used for several very different kinds of GPIO controller. (There is some +optional code supporting such an implementation strategy, described later +in this document, but drivers acting as clients to the GPIO interface must +not care how it's implemented.) That said, if the convention is supported on their platform, drivers should use it when possible. Platforms should declare GENERIC_GPIO support in @@ -121,6 +124,11 @@ before tasking is enabled, as part of early board setup. For output GPIOs, the value provided becomes the initial output value. This helps avoid signal glitching during system startup. +For compatibility with legacy interfaces to GPIOs, setting the direction +of a GPIO implicitly requests that GPIO (see below) if it has not been +requested already. That compatibility may be removed in the future; +explicitly requesting GPIOs is strongly preferred. + Setting the direction can fail if the GPIO number is invalid, or when that particular GPIO can't be used in that mode. It's generally a bad idea to rely on boot firmware to have set the direction correctly, since @@ -133,6 +141,7 @@ Spinlock-Safe GPIO access ------------------------- Most GPIO controllers can be accessed with memory read/write instructions. That doesn't need to sleep, and can safely be done from inside IRQ handlers. +(That includes hardirq contexts on RT kernels.) Use these calls to access such GPIOs: @@ -145,7 +154,7 @@ Use these calls to access such GPIOs: The values are boolean, zero for low, nonzero for high. When reading the value of an output pin, the value returned should be what's seen on the pin ... that won't always match the specified output value, because of -issues including wire-OR and output latencies. +issues including open-drain signaling and output latencies. The get/set calls have no error returns because "invalid GPIO" should have been reported earlier from gpio_direction_*(). However, note that not all @@ -170,7 +179,8 @@ get to the head of a queue to transmit a command and get its response. This requires sleeping, which can't be done from inside IRQ handlers. Platforms that support this type of GPIO distinguish them from other GPIOs -by returning nonzero from this call: +by returning nonzero from this call (which requires a valid GPIO number, +either explicitly or implicitly requested): int gpio_cansleep(unsigned gpio); @@ -209,8 +219,11 @@ before tasking is enabled, as part of early board setup. These calls serve two basic purposes. One is marking the signals which are actually in use as GPIOs, for better diagnostics; systems may have several hundred potential GPIOs, but often only a dozen are used on any -given board. Another is to catch conflicts between drivers, reporting -errors when drivers wrongly think they have exclusive use of that signal. +given board. Another is to catch conflicts, identifying errors when +(a) two or more drivers wrongly think they have exclusive use of that +signal, or (b) something wrongly believes it's safe to remove drivers +needed to manage a signal that's in active use. That is, requesting a +GPIO can serve as a kind of lock. These two calls are optional because not not all current Linux platforms offer such functionality in their GPIO support; a valid implementation @@ -223,6 +236,9 @@ Note that requesting a GPIO does NOT cause it to be configured in any way; it just marks that GPIO as in use. Separate code must handle any pin setup (e.g. controlling which pin the GPIO uses, pullup/pulldown). +Also note that it's your responsibility to have stopped using a GPIO +before you free it. + GPIOs mapped to IRQs -------------------- @@ -238,7 +254,7 @@ map between them using calls like: Those return either the corresponding number in the other namespace, or else a negative errno code if the mapping can't be done. (For example, -some GPIOs can't used as IRQs.) It is an unchecked error to use a GPIO +some GPIOs can't be used as IRQs.) It is an unchecked error to use a GPIO number that wasn't set up as an input using gpio_direction_input(), or to use an IRQ number that didn't originally come from gpio_to_irq(). @@ -299,17 +315,110 @@ Related to multiplexing is configuration and enabling of the pullups or pulldowns integrated on some platforms. Not all platforms support them, or support them in the same way; and any given board might use external pullups (or pulldowns) so that the on-chip ones should not be used. +(When a circuit needs 5 kOhm, on-chip 100 kOhm resistors won't do.) There are other system-specific mechanisms that are not specified here, like the aforementioned options for input de-glitching and wire-OR output. Hardware may support reading or writing GPIOs in gangs, but that's usually configuration dependent: for GPIOs sharing the same bank. (GPIOs are commonly grouped in banks of 16 or 32, with a given SOC having several such -banks.) Some systems can trigger IRQs from output GPIOs. Code relying on -such mechanisms will necessarily be nonportable. +banks.) Some systems can trigger IRQs from output GPIOs, or read values +from pins not managed as GPIOs. Code relying on such mechanisms will +necessarily be nonportable. -Dynamic definition of GPIOs is not currently supported; for example, as +Dynamic definition of GPIOs is not currently standard; for example, as a side effect of configuring an add-on board with some GPIO expanders. These calls are purely for kernel space, but a userspace API could be built -on top of it. +on top of them. + + +GPIO implementor's framework (OPTIONAL) +======================================= +As noted earlier, there is an optional implementation framework making it +easier for platforms to support different kinds of GPIO controller using +the same programming interface. + +As a debugging aid, if debugfs is available a /sys/kernel/debug/gpio file +will be found there. That will list all the controllers registered through +this framework, and the state of the GPIOs currently in use. + + +Controller Drivers: gpio_chip +----------------------------- +In this framework each GPIO controller is packaged as a "struct gpio_chip" +with information common to each controller of that type: + + - methods to establish GPIO direction + - methods used to access GPIO values + - flag saying whether calls to its methods may sleep + - optional debugfs dump method (showing extra state like pullup config) + - label for diagnostics + +There is also per-instance data, which may come from device.platform_data: +the number of its first GPIO, and how many GPIOs it exposes. + +The code implementing a gpio_chip should support multiple instances of the +controller, possibly using the driver model. That code will configure each +gpio_chip and issue gpiochip_add(). Removing a GPIO controller should be +rare; use gpiochip_remove() when it is unavoidable. + +Most often a gpio_chip is part of an instance-specific structure with state +not exposed by the GPIO interfaces, such as addressing, power management, +and more. Chips such as codecs will have complex non-GPIO state, + +Any debugfs dump method should normally ignore signals which haven't been +requested as GPIOs. They can use gpiochip_is_requested(), which returns +either NULL or the label associated with that GPIO when it was requested. + + +Platform Support +---------------- +To support this framework, a platform's Kconfig will "select HAVE_GPIO_LIB" +and arrange that its <asm/gpio.h> includes <asm-generic/gpio.h> and defines +three functions: gpio_get_value(), gpio_set_value(), and gpio_cansleep(). +They may also want to provide a custom value for ARCH_NR_GPIOS. + +Trivial implementations of those functions can directly use framework +code, which always dispatches through the gpio_chip: + + #define gpio_get_value __gpio_get_value + #define gpio_set_value __gpio_set_value + #define gpio_cansleep __gpio_cansleep + +Fancier implementations could instead define those as inline functions with +logic optimizing access to specific SOC-based GPIOs. For example, if the +referenced GPIO is the constant "12", getting or setting its value could +cost as little as two or three instructions, never sleeping. When such an +optimization is not possible those calls must delegate to the framework +code, costing at least a few dozen instructions. For bitbanged I/O, such +instruction savings can be significant. + +For SOCs, platform-specific code defines and registers gpio_chip instances +for each bank of on-chip GPIOs. Those GPIOs should be numbered/labeled to +match chip vendor documentation, and directly match board schematics. They +may well start at zero and go up to a platform-specific limit. Such GPIOs +are normally integrated into platform initialization to make them always be +available, from arch_initcall() or earlier; they can often serve as IRQs. + + +Board Support +------------- +For external GPIO controllers -- such as I2C or SPI expanders, ASICs, multi +function devices, FPGAs or CPLDs -- most often board-specific code handles +registering controller devices and ensures that their drivers know what GPIO +numbers to use with gpiochip_add(). Their numbers often start right after +platform-specific GPIOs. + +For example, board setup code could create structures identifying the range +of GPIOs that chip will expose, and passes them to each GPIO expander chip +using platform_data. Then the chip driver's probe() routine could pass that +data to gpiochip_add(). + +Initialization order can be important. For example, when a device relies on +an I2C-based GPIO, its probe() routine should only be called after that GPIO +becomes available. That may mean the device should not be registered until +calls for that GPIO can work. One way to address such dependencies is for +such gpio_chip controllers to provide setup() and teardown() callbacks to +board specific code; those board specific callbacks would register devices +once all the necessary resources are available. diff --git a/Documentation/i2c/chips/pca9539 b/Documentation/i2c/chips/pca9539 index c4fce6a13537..1d81c530c4a5 100644 --- a/Documentation/i2c/chips/pca9539 +++ b/Documentation/i2c/chips/pca9539 @@ -1,6 +1,9 @@ Kernel driver pca9539 ===================== +NOTE: this driver is deprecated and will be dropped soon, use +drivers/gpio/pca9539.c instead. + Supported chips: * Philips PCA9539 Prefix: 'pca9539' diff --git a/Documentation/pcmcia/driver-changes.txt b/Documentation/pcmcia/driver-changes.txt index 4739c5c3face..96f155e68750 100644 --- a/Documentation/pcmcia/driver-changes.txt +++ b/Documentation/pcmcia/driver-changes.txt @@ -33,8 +33,8 @@ This file details changes in 2.6 which affect PCMCIA card driver authors: and can be used (e.g. for SET_NETDEV_DEV) by using handle_to_dev(client_handle_t * handle). -* Convert internal I/O port addresses to unsigned long (as of 2.6.11) - ioaddr_t should be replaced by kio_addr_t in PCMCIA card drivers. +* Convert internal I/O port addresses to unsigned int (as of 2.6.11) + ioaddr_t should be replaced by unsigned int in PCMCIA card drivers. * irq_mask and irq_list parameters (as of 2.6.11) The irq_mask and irq_list parameters should no longer be used in diff --git a/Documentation/pm_qos_interface.txt b/Documentation/pm_qos_interface.txt new file mode 100644 index 000000000000..49adb1a33514 --- /dev/null +++ b/Documentation/pm_qos_interface.txt @@ -0,0 +1,59 @@ +PM quality of Service interface. + +This interface provides a kernel and user mode interface for registering +performance expectations by drivers, subsystems and user space applications on +one of the parameters. + +Currently we have {cpu_dma_latency, network_latency, network_throughput} as the +initial set of pm_qos parameters. + +The infrastructure exposes multiple misc device nodes one per implemented +parameter. The set of parameters implement is defined by pm_qos_power_init() +and pm_qos_params.h. This is done because having the available parameters +being runtime configurable or changeable from a driver was seen as too easy to +abuse. + +For each parameter a list of performance requirements is maintained along with +an aggregated target value. The aggregated target value is updated with +changes to the requirement list or elements of the list. Typically the +aggregated target value is simply the max or min of the requirement values held +in the parameter list elements. + +From kernel mode the use of this interface is simple: +pm_qos_add_requirement(param_id, name, target_value): +Will insert a named element in the list for that identified PM_QOS parameter +with the target value. Upon change to this list the new target is recomputed +and any registered notifiers are called only if the target value is now +different. + +pm_qos_update_requirement(param_id, name, new_target_value): +Will search the list identified by the param_id for the named list element and +then update its target value, calling the notification tree if the aggregated +target is changed. with that name is already registered. + +pm_qos_remove_requirement(param_id, name): +Will search the identified list for the named element and remove it, after +removal it will update the aggregate target and call the notification tree if +the target was changed as a result of removing the named requirement. + + +From user mode: +Only processes can register a pm_qos requirement. To provide for automatic +cleanup for process the interface requires the process to register its +parameter requirements in the following way: + +To register the default pm_qos target for the specific parameter, the process +must open one of /dev/[cpu_dma_latency, network_latency, network_throughput] + +As long as the device node is held open that process has a registered +requirement on the parameter. The name of the requirement is "process_<PID>" +derived from the current->pid from within the open system call. + +To change the requested target value the process needs to write a s32 value to +the open device node. This translates to a pm_qos_update_requirement call. + +To remove the user mode request for a target value simply close the device +node. + + + diff --git a/Documentation/sysctl/vm.txt b/Documentation/sysctl/vm.txt index 6f31f0a247d0..24eac1bc735d 100644 --- a/Documentation/sysctl/vm.txt +++ b/Documentation/sysctl/vm.txt @@ -22,6 +22,7 @@ Currently, these files are in /proc/sys/vm: - dirty_background_ratio - dirty_expire_centisecs - dirty_writeback_centisecs +- highmem_is_dirtyable (only if CONFIG_HIGHMEM set) - max_map_count - min_free_kbytes - laptop_mode @@ -40,9 +41,9 @@ Currently, these files are in /proc/sys/vm: ============================================================== dirty_ratio, dirty_background_ratio, dirty_expire_centisecs, -dirty_writeback_centisecs, vfs_cache_pressure, laptop_mode, -block_dump, swap_token_timeout, drop-caches, -hugepages_treat_as_movable: +dirty_writeback_centisecs, highmem_is_dirtyable, +vfs_cache_pressure, laptop_mode, block_dump, swap_token_timeout, +drop-caches, hugepages_treat_as_movable: See Documentation/filesystems/proc.txt |