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diff --git a/sysfsutils/docs/libsysfs.txt b/sysfsutils/docs/libsysfs.txt deleted file mode 100644 index 7ab1147..0000000 --- a/sysfsutils/docs/libsysfs.txt +++ /dev/null @@ -1,1376 +0,0 @@ - - System Utilities sysfs Library - libsysfs - ========================================= - -Version: 2.1.0 -August 22, 2006 - -Contents --------- -1. Introduction -2. Requirements -3. Definitions -4. Overview -5. Data Structures - 5.1 Attribute Data Structure - 5.2 Bus Data Structure - 5.3 Class Data Structures - 5.4 Device Data Structure - 5.5 Driver Data Structure - 5.6 Module Data Structure -6. Functions - 6.1 Calling Conventions in Libsysfs - 6.2 Utility Functions - 6.3 Attribute Functions - 6.4 Bus Functions - 6.5 Class Functions - 6.6 Device Functions - 6.7 Driver Functions - 6.8 Module functions -7. Dlists - 7.1 Navigating a dlist - 7.2 Custom sorting using dlist_sort_custom() - 7.3 Custom filtering and sorting using dlist_filter_sort() -8. Usage -9. Testsuite -10. Conclusion - - -1. Introduction ---------------- - -Libsysfs' purpose is to provide a consistent and stable interface for -querying system device information exposed through the sysfs filesystem. -The library implements functions for querying filesystem information, -such as reading directories and files. It also contains routines for -working with buses, classes, and the device tree. - - -2. Requirements ---------------- - -The library must satisfy the following requirements: - -- It must provide a stable programming interfaces that applications can - be built upon. - -- It must provide functions to retrieve device Vital Product Data (VPD) - information for Error Log Analysis (ELA) support. ELA will provide - device driver and device bus address information. - -- It must provide access to all system devices and information exposed - by sysfs. - -- It must provide a function to find sysfs' current mount point. - -- It must provide a function for udev to retrieve a device's major and - minor numbers. - - -3. Definitions --------------- - -- sysfs: Sysfs is a virtual filesystem in 2.5+ Linux kernels that - presents a hierarchical representation of all system physical and - virtual devices. It presents system devices by bus, by class, and - by topology. Callbacks to device drivers are exposed as files in - device directories. Sysfs, for all purposes, is our tree of system - devices. For more information, please see: - - http://www.kernel.org/pub/linux/kernel/people/mochel/doc/ - -- udev: Udev is Greg Kroah-Hartman's User Space implementation of devfs. - Udev creates /dev nodes for devices upon Hotplug events. The Hotplug - event provides udev with a sysfs directory location of the device. Udev - must use that directory to grab device's major and minor number, which it - will use to create the /dev node. For more information, please see: - - http://www.kernel.org/pub/linux/utils/kernel/hotplug/ - - Udev provides persistent device naming based on a set of user specified - rules. The rules a device name is based on could one or a combination of a - number of parameters such as the bus the device is on, the serial number - of the device (in case of USB), the vendor name (in case of SCSI) and so - on. Udev uses Libsysfs to retrieve relevent information to appropriately - name devices. - - -4. Overview ------------ - -Libsysfs grew from a common need. There are several applications under -development that need access to sysfs and system devices. Udev, on a -hotplug event, must take a sysfs device path and create a /dev node. Our -diagnostic client needs to list all system devices. Finally, our Error -Log Analysis piece is required to retrieve VPD information for a -failing device. We divided to create a single library interface rather -than having these separate applications create their own accesses to -sysfs involving reading directories and files. - -Libsysfs will also provide stability for applications to be built upon. Sysfs -currently doesn't enforce any standards for callback or file names. File -names change depending on bus or class. Sysfs is also changing, it is -currently being developed. Libsysfs will provide a stable interface to -applications while allowing sysfs to change underneath it. - -Like sysfs, the library will provide devices to applications by bus, by -class, and by topology. The library will function similar to directories -and files that lie underneath it. To query a device on a PCI bus, one would -"open" the bus to scan or read devices and "close" the bus when -completed. Besides supplying functions to retrieve devices, the library -will also provide some utility functions like getting sysfs mount point. - -A paper on Libsysfs was presented at Linux.Conf.Au 2004 (Adelaide, January -2004). The paper is available online at: - -http://oss.software.ibm.com/linux/papers/libsysfs/libsysfs-linuxconfau2004.pdf - - -5. Data Structures ------------------- - -Libsysfs will classify system devices following sysfs' example, dividing -them by bus, class, and devices. The library presents this information -generically. It doesn't, for example, differentiate between PCI and USB -buses. Device attributes are presented with values as they are exposed -by sysfs, the values are not formatted. - -The library will provide standard definitions for working with sysfs -and devices, here's some examples: - -#define SYSFS_FSTYPE_NAME "sysfs" -#define SYSFS_PROC_MNTS "/proc/mounts" -#define SYSFS_BUS_NAME "bus" -#define SYSFS_CLASS_NAME "class" -#define SYSFS_BLOCK_NAME "block" -#define SYSFS_DEVICES_NAME "devices" -#define SYSFS_DRIVERS_NAME "drivers" -#define SYSFS_NAME_ATTRIBUTE "name" -#define SYSFS_MOD_PARM_NAME "parameters" -#define SYSFS_MOD_SECT_NAME "sections" -#define SYSFS_UNKNOWN "unknown" -#define SYSFS_PATH_ENV "SYSFS_PATH" - -The library uses some definitions to mark maximum size of a sysfs name or -path length: - -#define SYSFS_PATH_MAX 256 -#define SYSFS_NAME_LEN 64 -#define SYSFS_BUS_ID_SIZE 32 - - -NOTE: - a. As of release 0.4.0 of sysfsutils, a number of changes have been - made so that the dlists and "directory" references in all libsysfs's - structures are not populated until such time that it is absolutely - necessary. Hence, these elements may not contain valid data at all - times (as was the case before). - b. As of release 1.0.0 of sysfsutils, all dlists in the library are - sorted in alphabetical order. It is now a requirement that the - "name" and "path" be the first two elements of all libsysfs - structures. - c. There has been a major overhaul with 2.0.0 release of sysfsutils. - We now have a much leaner and meaner library without the overhead - of the sysfs_directory and related structures. The API list has - also been pruned to contain the most frequently used calls and - the lists are not populated all at once. This has lead to enormous - speed improvements as well as reduction in the number of system - calls. - - -5.1 Attribute Data Structure -------------------------------------------- - -The library implements structure to represent sysfs files. - -A file in sysfs represents a device or driver attribute. Attributes can be -read only, write only, or read and write. File data can be ASCII and -binary. The library has the following structure to represent files: - -struct sysfs_attribute { - char name[SYSFS_NAME_LEN]; - char path[SYSFS_PATH_MAX]; - char *value; - unsigned short len; /* value length */ - enum sysfs_attribute_method method; /* show and store */ -}; - -Path represents the file/attribute's full path. Value is used when reading -from or writing to an attribute. "len" is the length of data in "value". -Method is an enum for defining if the attribute supports show(read) and/or -store(write). - - -5.2 Bus Data Structure ----------------------- - -All buses look similar in sysfs including lists of devices and drivers, -therefore we use the following structure to represent all sysfs buses: - -struct sysfs_bus { - char name[SYSFS_NAME_LEN]; - char path[SYSFS_PATH_MAX]; - struct dlist *attrlist; - - /* Private: for internal use only */ - struct dlist *drivers; - struct dlist *devices; -}; - -The sysfs_bus structure contains the bus "name", while the "path" to bus -directory is also stored. It also contains lists of devices on the bus -and drivers that are registered on it. - - -5.3 Class Data Structures -------------------------- - -The library uses two data structures to represent classes in sysfs. Sysfs -classes contains a class directory like "net" or "scsi_host" and then -class devices like "eth0", "lo", or "eth1" for the "net" class. - -struct sysfs_class { - char name[SYSFS_NAME_LEN]; - char path[SYSFS_PATH_MAX]; - struct dlist *attrlist; - - /* Private: for internal use only */ - struct dlist *devices; -}; - -The sysfs_class represents device classes in sysfs like "net". It contains -the class "name", "path" to the class and a list of class devices - -struct sysfs_class_device { - char name[SYSFS_NAME_LEN]; - char path[SYSFS_PATH_MAX]; - struct dlist *attrlist; - char classname[SYSFS_NAME_LEN]; - - /* Private: for internal use only */ - struct sysfs_class_device *parent; - struct sysfs_device *sysdevice; /* NULL if virtual */ -}; - -A class device isn't the same as a sysfs_device, it's specific to the class in -which it belongs. The class device structure contains the name of the class -the class device belongs to and its sysfs_device reference. It also contains -the name of the class device - like "eth0", its parent (if present). - -5.4 Device Data Structure -------------------------- - -The sysfs_device structure represents a system device that's exposed -in sysfs under the /sys/devices directory structure. - -struct sysfs_device { - char name[SYSFS_NAME_LEN]; - char path[SYSFS_PATH_MAX]; - struct dlist *attrlist; - char bus_id[SYSFS_NAME_LEN]; - char bus[SYSFS_NAME_LEN]; - char driver_name[SYSFS_NAME_LEN]; - char subsystem[SYSFS_NAME_LEN]; - - /* Private: for internal use only */ - struct sysfs_device *parent; - struct dlist *children; -}; - -The sysfs_device structure contains a "parent" pointer, a list of child -devices, if any, device's directory, its bus id - which is the name of -device's directory, the bus name on which this device is registered and -its driver name. The device structure also contains the absolute path -to the device. - - -5.5 Driver Data Structure -------------------------- - -The sysfs_driver structure represents a device driver. - -struct sysfs_driver { - char name[SYSFS_NAME_LEN]; - char path[SYSFS_PATH_MAX]; - struct dlist *attrlist; - char bus[SYSFS_NAME_LEN]; - - /* Private: for internal use only */ - struct sysfs_module *module; - struct dlist *devices; -}; - -The sysfs_driver structure contains a list of devices that use this driver, -the name of the driver, the module it is using and a list of attributes -for the driver. - - -5.6 Module Data Structure -------------------------- -The sysfs_module structure represents the module loaded in the system. - -struct sysfs_module { - char name[SYSFS_NAME_LEN]; - char path[SYSFS_PATH_MAX]; - struct dlist *attrlist; - struct dlist *parmlist; - struct dlist *sections; -}; - -The sysfs_module structure contains a list of attributes, parameters and -sections used by the corresponding module. It also contains name of the -module, its path. The following functions can be used to retrive the -information related to the module. - -struct dlist *sysfs_get_module_parms(struct sysfs_module *module) -struct dlist *sysfs_get_module_sections(struct sysfs_module *module) -struct dlist *sysfs_get_module_attributes(struct sysfs_module *module) - -6. Functions ------------- - -Libsysfs will provide functions to access system devices by bus, by class, -and by device. Functions will act like accessing directories and files, -using "open" and "close". Open returns a structure and close is used -to clean that structure up. - - -6.1 Calling Conventions in Libsysfs ------------------------------------ - -Libsysfs uses a simple API calling convention. APIs are classified to be -one of "open", "get", "close" types. The convention is as follows: - - a. All "open" APIs have a corresponding "close" API. - b. References obtained using "get" calls should not be closed - explicitly. - c. All "opened" references have to be closed with a call to - their corresponding "close" call. This takes care of - freeing structure references obtained with "get" calls. - - -6.2 Utility Functions ---------------------- - -The library will provide a few utility functions for working with sysfs. - -------------------------------------------------------------------------------- -Name: sysfs_get_mnt_path - -Description: Function finds the mount path for filesystem type "sysfs". - -Arguments: char *mnt_path Mount path buffer - size_t len Size of mount path buffer - -Returns: Zero with success. - -1 with error. Errno will be set with error: - - EINVAL for invalid argument, if buffer is NULL or - if len is zero - -Prototype: sysfs_get_mnt_path(char *mnt_path, size_t len); -------------------------------------------------------------------------------- - -------------------------------------------------------------------------------- -Name: sysfs_get_name_from_path - -Description: Function returns the last directory or file name from the - included path. - -Arguments: const char *path Path to parse name from - char *name Buffer to put parsed name into - size_t *len Size of name buffer - -Returns: 0 with success. - -1 on Error. Errno will be set with error, returning - - EINVAL for invalid arguments - -Prototype: int sysfs_get_name_from_path(const char *path, - char *name, size_t *len) -------------------------------------------------------------------------------- - -------------------------------------------------------------------------------- -Name: sysfs_get_link - -Description: Sysfs readlink function, reads the link at supplied path - and returns its target path. - -Arguments: const char *path Link's path - char *target Buffer to place link's target - size_t len Size of target buffer - -Returns: 0 with success - -1 with error. Errno will be set with error, returning - - EINVAL for invalid arguments - -Prototype: int sysfs_get_link(const char *path, char *target, size_t len) -------------------------------------------------------------------------------- - -------------------------------------------------------------------------------- -Name: sysfs_close_list - -Description: Closes a given dlist. This can be used as a generic list close - routine. - -Arguments: struct dlist *list List to be closed - -Prototype: void sysfs_close_list(struct dlist *list) -------------------------------------------------------------------------------- - -------------------------------------------------------------------------------- -Name: sysfs_path_is_dir - -Description: Utility function to verify if a given path is to a directory. - -Arguments: const char *path Path to verify - -Returns: 0 on success, 1 on error - - EINVAL for invalid arguments - -Prototype: int sysfs_path_is_dir(const char *path) -------------------------------------------------------------------------------- - -------------------------------------------------------------------------------- -Name: sysfs_path_is_file - -Description: Utility function to verify if a given path is to a file. - -Arguments: const char *path Path to verify - -Returns: 0 on success, 1 on error - - EINVAL for invalid arguments - -Prototype: int sysfs_path_is_file(const char *path) -------------------------------------------------------------------------------- - -------------------------------------------------------------------------------- -Name: sysfs_path_is_link - -Description: Utility function to verify if a given path is to a link. - -Arguments: const char *path Path to verify - -Returns: 0 on success, 1 on error - - EINVAL for invalid arguments - -Prototype: int sysfs_path_is_link(const char *path) -------------------------------------------------------------------------------- - -------------------------------------------------------------------------------- -Name: sysfs_open_directory_list - -Description: Utility function to get list of all directories under path. - -Arguments: const char *path Path to read - -Returns: Directory list on success, NULL on error - -Prototype: struct dlist *sysfs_open_directory_list(const char *path) -------------------------------------------------------------------------------- - -------------------------------------------------------------------------------- -Name: sysfs_open_link_list - -Description: Utility function to get list of all links under path. - -Arguments: const char *path Path to read - -Returns: Links list on success, NULL on error - -Prototype: struct dlist *sysfs_open_link_list(const char *path) -------------------------------------------------------------------------------- - -6.3 Attribute Functions ------------------------- - -Libsysfs provides a set of functions to open, read, and close attributes in sysfs. These functions mirror their filesystem function counterparts. - -Along with the usual open, read, and close functions, libsysfs provides -a couple other functions for accessing attribute values. - -------------------------------------------------------------------------------- -Name: sysfs_open_attribute - -Description: Opens up a file in sysfs and creates a sysfs_attribute - structure. File isn't read with this function. - -Arguments: const char *path File/Attribute's path - -Returns: struct sysfs_attribute * with success. - NULL with error. Errno will be set with error, returning - - EINVAL for invalid arguments - -Prototype: struct sysfs_attribute *sysfs_open_attribute(const char *path) -------------------------------------------------------------------------------- - -------------------------------------------------------------------------------- -Name: sysfs_close_attribute - -Description: Cleans up and closes sysfs_attribute structure. - -Arguments: struct sysfs_attribute *sysattr Attribute to close - -Prototype: void sysfs_close_attribute(struct sysfs_attribute *sysattr) -------------------------------------------------------------------------------- - -------------------------------------------------------------------------------- -Name: sysfs_read_attribute - -Description: Reads the supplied attribute. Since the maximum transfer - from a sysfs attribute is a pagesize, function reads in - up to a page from the file and stores it in the "value" - field in the attribute. - -Arguments: struct sysfs_attribute *sysattr Attribute to read - -Returns: 0 with success. - -1 with error. Errno will be set with error, returning - - EINVAL for invalid arguments - -Prototype: int sysfs_read_attribute(struct sysfs_attribute *sysattr) -------------------------------------------------------------------------------- - -------------------------------------------------------------------------------- -Name: sysfs_write_attribute - -Description: Writes to the supplied attribute. Function validates if the - given attribute is writable, and writes the new value to the - attribute. Value to write as well as its length is user - supplied. In case the length written is not equal to the - length requested to be written, the original value is - restored and an error is returned. - -Arguments: struct sysfs_attribute *sysattr Attribute to write to - const char *new_value sysattr's new value - size_t len Length of "new_value" - -Returns: 0 with success. - -1 with error. Errno will be set with error, returning - - EINVAL for invalid arguments - -Prototype: int sysfs_write_attribute(struct sysfs_attribute *sysattr, - const char *new_value, size_t len) -------------------------------------------------------------------------------- - -6.4 Bus Functions ------------------ - -The library provides a functions for viewing buses represented in sysfs. -The sysfs_open_bus opens a bus in the /sys/bus directory, such as "pci", -"usb", or "scsi". The open command returns a sysfs_bus structure that -contains a list of the bus' devices. The sysfs_close_bus function is -used to clean up the bus structure. Given a device or a driver, -functions are provided to determine what bus they are on. - -------------------------------------------------------------------------------- -Name: sysfs_open_bus - -Description: Function opens up one of the buses represented in sysfs in - the /sys/bus directory. It returns a sysfs_bus structure - that includes a list of bus devices and drivers. - -Arguments: const char *name Bus name to open, like "pci"... - -Returns: struct sysfs_bus * with success - NULL with error. Errno will be set with error, returning - - EINVAL for invalid arguments - -Prototype: struct sysfs_bus *sysfs_open_bus(const char *name) -------------------------------------------------------------------------------- - -------------------------------------------------------------------------------- -Name: sysfs_close_bus - -Description: Function closes up the sysfs_bus structure including its - devices, and drivers and the list of attributes. - -Arguments: sysfs_bus *bus Bus structure to close - -Prototype: void sysfs_close_bus(struct sysfs_bus *bus) -------------------------------------------------------------------------------- - -------------------------------------------------------------------------------- -Name: sysfs_get_bus_devices - -Description: Function returns a list of devices that are registered with - this bus. - -Arguments: struct sysfs_bus *bus Bus whose devices list to return - -Returns: struct dlist * of sysfs_devices on success - NULL with error. Errno will be sent with error, returning - - EINVAL for invalid arguments - -Prototype: struct dlist *sysfs_get_bus_devices(struct sysfs_bus *bus) -------------------------------------------------------------------------------- - -------------------------------------------------------------------------------- -Name: sysfs_get_bus_drivers - -Description: Function returns a list of drivers that are registered with - this bus. - -Arguments: struct sysfs_bus *bus Bus whose drivers list to return - -Returns: struct dlist * of sysfs_drivers on success - NULL with error. Errno will be sent with error, returning - - EINVAL for invalid arguments - -Prototype: struct dlist *sysfs_get_bus_drivers(struct sysfs_bus *bus) -------------------------------------------------------------------------------- - -------------------------------------------------------------------------------- -Name: sysfs_get_bus_device - -Description: Function takes a sysfs_bus structure(obtained on a successful - return from a sysfs_open_bus() call) and looks for the given - device on this bus. On success, it returns a sysfs_device - structure corresponding to the device. - -Arguments: struct sysfs_bus *bus Bus structure on which to search - char *id Device to look for - -Returns: struct sysfs_device * with success - NULL with error. Errno will be set with error, returning - - EINVAL for invalid arguments - -Prototype: struct sysfs_device *sysfs_get_bus_device - (struct sysfs_bus *bus, char *id) -------------------------------------------------------------------------------- - -------------------------------------------------------------------------------- -Name: sysfs_get_bus_driver - -Description: Function takes a sysfs_bus structure (obtained on a successful - return from a sysfs_open_bus() call) and looks for the given - driver on this bus. On success, it returns a sysfs_driver - structure corresponding to the driver. - -Arguments: struct sysfs_bus *bus Bus structure on which to search - char *drvname Driver to look for - -Returns: struct sysfs_driver * with success - NULL with error. Errno will be set with error, returning - - EINVAL for invalid arguments - -Prototype: struct sysfs_device *sysfs_get_bus_driver - (struct sysfs_bus *bus, char *drvname) -------------------------------------------------------------------------------- - -6.5 Class Functions -------------------- - -Libsysfs provides functions to open sysfs classes and their class devices. -These functions too operate with open and close, close must be called to -clean up the class structures. Given a class device name, functions are -provided to determine what class they belong to. Once a class device -name and the class it belongs to is known, a function to open the -class device is provided. This method can be used when details of -a single class device is required. - -------------------------------------------------------------------------------- -Name: sysfs_open_class - -Description: Function opens up one of the classes represented in sysfs in - the /sys/class directory. It returns a sysfs_class structure - that includes a list of class devices. - -Arguments: const char *name Class name to open, like "net".. - -Returns: struct sysfs_class * with success - NULL with error. Errno will be set with error, returning - - EINVAL for invalid arguments - -Prototype: struct sysfs_class *sysfs_open_class(const char *name) -------------------------------------------------------------------------------- - -------------------------------------------------------------------------------- -Name: sysfs_close_class - -Description: Function closes up the sysfs_class structure including its - class devices. - -Arguments: sysfs_class *cls Class structure to close - -Prototype: void sysfs_close_class(struct sysfs_class *cls); -------------------------------------------------------------------------------- - -------------------------------------------------------------------------------- -Name: sysfs_open_class_device_path - -Description: Function opens up one of the class devices represented in - sysfs in sysfs/class/"class"/ directory. It returns a - sysfs_class_device structure. - -Arguments: const char *path Path to class device - -Returns: struct sysfs_class_device * with success - NULL with error. Errno will be set with error, returning - - EINVAL for invalid arguments - -Prototype: struct sysfs_class_device *sysfs_open_class_device_path - (const char *path) -------------------------------------------------------------------------------- - -------------------------------------------------------------------------------- -Name: sysfs_close_class_device - -Description: Function closes up the sysfs_class_device structure. - -Arguments: sysfs_class_device *dev Class device structure to close - -Prototype: void sysfs_close_class_device(struct sysfs_class_device *dev) -------------------------------------------------------------------------------- - -------------------------------------------------------------------------------- -Name: sysfs_get_class_device - -Description: Function takes a sysfs_class structure(obtained on a successful - return from a sysfs_open_class() call) and looks for the given - device in this class. On success, it returns a - sysfs_class_device structure corresponding to the class device. - -Arguments: struct sysfs_class *cls Class on which to search - char *name Class device "name" to look for - -Returns: struct sysfs_class_device * with success - NULL with error. Errno will be set with error, returning - - EINVAL for invalid arguments - -Prototype: struct sysfs_class_device *sysfs_get_class_device - (struct sysfs_class *cls, char *name) -------------------------------------------------------------------------------- - -------------------------------------------------------------------------------- -Name: sysfs_get_class_devices - -Description: Function returns a list of class devices for the given class. - -Arguments: struct sysfs_class *cls Class whose class device list - is required - -Returns: struct dlist * of sysfs_class_devices on success - NULL with error. Errno will be set with error, returning - - EINVAL for invalid arguments - -Prototype: struct dlist *sysfs_get_class_devices(struct sysfs_class *cls) -------------------------------------------------------------------------------- - -------------------------------------------------------------------------------- -Name: sysfs_open_class_device - -Description: Given the name of the class on which to look for, this function - locates a given class device and returns a sysfs_class_device - structure corresponding to the requested class device. - - NOTE: - 1. The sysfs_class_device structure obtained upon successful - return from this function has to be closed by calling - sysfs_close_class_device(). - 2. Class this device belongs to must be known prior to calling - this function. - -Arguments: const char *classname Class on which to search - char *name Class device "name" to open - -Returns: struct sysfs_class_device * with success - NULL with error. Errno will be set with error, returning - - EINVAL for invalid arguments - -Prototype: struct sysfs_class_device *sysfs_open_class_device - (const char *classname, char *name) -------------------------------------------------------------------------------- - -------------------------------------------------------------------------------- -Name: sysfs_get_classdev_device - -Description: Function returns the sysfs_device reference (if present) for the - given class device. - -Arguments: struct sysfs_class_device *clsdev Class device whose - sysfs_device reference - is required - -Returns: struct sysfs_device * on success - NULL with error. Errno will be set with error, returning - - EINVAL for invalid arguments - -Prototype: struct sysfs_device *sysfs_get_classdev_device - (struct sysfs_class_device *clsdev) -------------------------------------------------------------------------------- - -------------------------------------------------------------------------------- -Name: sysfs_get_classdev_parent - -Description: Function returns the sysfs_class_device reference for the - parent (if present) of the given class device. - -Arguments: struct sysfs_class_device *clsdev Class device whose - parent reference - is required - -Returns: struct sysfs_class_device * on success - NULL with error. Errno will be set with error, returning - - EINVAL for invalid arguments - -Prototype: struct sysfs_class_device *sysfs_get_classdev_parent - (struct sysfs_class_device *clsdev) -------------------------------------------------------------------------------- - -------------------------------------------------------------------------------- -Name: sysfs_get_classdev_attributes - -Description: Function takes a sysfs_class_device structure and returns a - list of attributes for the class device. - -Arguments: struct sysfs_class_device *cdev Class device for which - attributes are required - -Returns: struct dlist * of attributes with success - NULL with error. Errno will be set with error, returning - - EINVAL for invalid arguments - -Prototype: struct dlist *sysfs_get_classdev_attributes - (struct sysfs_class_device *cdev) -------------------------------------------------------------------------------- - -------------------------------------------------------------------------------- -Name: sysfs_get_classdev_attr - -Description: Searches supplied class device's attributes by name and returns - the attribute. - -Arguments: struct sysfs_class_device *clsdev Device to search - const char *name Attribute name to find - -Returns: struct sysfs_attribute * with success - NULL with error. Errno will be set with error, returning - - EINVAL for invalid arguments - -Prototype: struct sysfs_attribute *sysfs_get_classdev_attr - (struct sysfs_class_device *clsdev, const char *name) -------------------------------------------------------------------------------- - -6.6 Device Functions --------------------- - -Devices represent everything in sysfs under /sys/devices, which is a -hierarchical view of system devices. Besides the expected open and -close functions, libsysfs provides open and close functions for -root devices. These functions recursively open or close a device -and all of its children. - -------------------------------------------------------------------------------- -Name: sysfs_open_device_path - -Description: Opens up a device at a specific path. It opens the device's - directory, reads the directory, and returns a sysfs_device - structure. - -Arguments: const char *path Path to device - -Returns: struct sysfs_device * with success - NULL with error. Errno will be set with error, returning - - EINVAL for invalid arguments - -Prototype: struct sysfs_device *sysfs_open_device_path(const char *path) -------------------------------------------------------------------------------- - -------------------------------------------------------------------------------- -Name: sysfs_close_device - -Description: Function closes up the sysfs_device structure. - -Arguments: sysfs_device *dev Device structure to close - -Prototype: void sysfs_close_device(struct sysfs_device *dev) -------------------------------------------------------------------------------- - -------------------------------------------------------------------------------- -Name: sysfs_open_device_tree - -Description: Function opens up the device tree at the specified path. - -Arguments: const char *path Path at which to open the device tree - -Returns: struct sysfs_device * with success - NULL with error, Errno will be set with error, returning - - EINVAL for invalid arguments - -Prototype: struct sysfs_device *sysfs_open_device_tree(const char *path) -------------------------------------------------------------------------------- - -------------------------------------------------------------------------------- -Name: sysfs_close_device_tree - -Description: Function closes the device tree originating at the given - sysfs_device. - -Arguments: struct sysfs_device *devroot Device from which the device - tree has to be closed - -Prototype: void sysfs_close_device_tree(struct sysfs_device *devroot) -------------------------------------------------------------------------------- - -------------------------------------------------------------------------------- -Name: sysfs_get_device_parent - -Description: Function returns the sysfs_device reference for the parent - (if present) of the given sysfs_device. - -Arguments: struct sysfs_device *dev sysfs_device whose parent - reference is required - -Returns: struct sysfs_device * on success - NULL with error. Errno will be set with error, returning - - EINVAL for invalid arguments - -Prototype: struct sysfs_device *sysfs_get_device_parent - (struct sysfs_device *dev) -------------------------------------------------------------------------------- - - -------------------------------------------------------------------------------- -Name: sysfs_get_device_attr - -Description: Searches supplied device's attributes by name and returns - the attribute. - -Arguments: struct sysfs_device *dev Device to search - const char *name Attribute name to find - -Returns: struct sysfs_attribute * with success - NULL with error. Errno will be set with error, returning - - EINVAL for invalid arguments - -Prototype: struct sysfs_attribute *sysfs_get_device_attr - (struct sysfs_device *dev, const char *name) -------------------------------------------------------------------------------- - -------------------------------------------------------------------------------- -Name: sysfs_get_device_attributes - -Description: Function takes a sysfs_device structure and returns a list - of attributes for the device. - -Arguments: struct sysfs_device *device Device for which - attributes are required - -Returns: struct dlist * of attributes with success - NULL with error. Errno will be set with error, returning - - EINVAL for invalid arguments - -Prototype: struct dlist *sysfs_get_device_attributes - (struct sysfs_device *device) -------------------------------------------------------------------------------- - -------------------------------------------------------------------------------- -Name: sysfs_open_device - -Description: Given the name of the bus on which to look for, this function - locates a given device and returns a sysfs_device structure - corresponding to the requested device. - -Arguments: const char *bus Bus on which to search - const char *bus_id Device to look for - -Returns: struct sysfs_device * with success - NULL with error. Errno will be set with error, returning - - EINVAL for invalid arguments - -Prototype: struct sysfs_device *sysfs_open_device - (const char *bus, const char *bus_id) -------------------------------------------------------------------------------- - -------------------------------------------------------------------------------- -Name: sysfs_get_device_bus - -Description: Given a sysfs_device, this function fills in the bus this - device is on in the sysfs_device->bus field. - -Arguments: struct sysfs_device *dev Device whose bus name to find - -Returns: 0 with success. - -1 with error. Errno will be set with error, returning - - EINVAL for invalid arguments - -Prototype: int sysfs_get_device_bus(struct sysfs_device *dev) -------------------------------------------------------------------------------- - -6.7 Driver Functions --------------------- - -Drivers are represented in sysfs under the /sys/bus/xxx/drivers (xxx being -the bus type, such as "pci", "usb, and so on). Functions are provided to -open and close drivers. - -------------------------------------------------------------------------------- -Name: sysfs_open_driver_path - -Description: Opens driver at specific path. - -Arguments: const char *path Path to driver - -Returns: struct sysfs_driver * with success - NULL with error. Errno will be set with error, returning - - EINVAL for invalid arguments - -Prototype: struct sysfs_driver *sysfs_open_driver_path(const char *path) -------------------------------------------------------------------------------- - -------------------------------------------------------------------------------- -Name: sysfs_close_driver - -Description: Closes and cleans up sysfs_driver structure. - -Arguments: sysfs_driver *driver Driver structure to close - -Prototype: void sysfs_close_driver(struct sysfs_driver *driver) -------------------------------------------------------------------------------- - -------------------------------------------------------------------------------- -Name: sysfs_get_driver_devices - -Description: Function returns a list of devices that use this driver. - -Arguments: struct sysfs_driver *driver Driver whose devices list is - required - -Returns: struct dlist * of sysfs_devices on success - NULL with error. Errno will be set with error, returning - - EINVAL for invalid arguments - -Prototype: struct dlist *sysfs_get_driver_devices - (struct sysfs_driver *driver) -------------------------------------------------------------------------------- - -------------------------------------------------------------------------------- -Name: sysfs_get_driver_attr - -Description: Searches supplied driver's attributes by name and returns - the attribute. - -Arguments: struct sysfs_driver *drv Driver to search - const char *name Attribute name to find - -Returns: struct sysfs_attribute * with success - NULL with error. Errno will be set with error, returning - - EINVAL for invalid arguments - -Prototype: struct sysfs_attribute *sysfs_get_driver_attr - (struct sysfs_driver *drv, const char *name) -------------------------------------------------------------------------------- - -------------------------------------------------------------------------------- -Name: sysfs_get_driver_attributes - -Description: Function takes a sysfs_driver structure and returns a list - of attributes for the driver. - -Arguments: struct sysfs_driver *driver Driver for which attributes - are required - -Returns: struct dlist * of attributes with success - NULL with error. Errno will be set with error, returning - - EINVAL for invalid arguments - -Prototype: struct dlist *sysfs_get_driver_attributes - (struct sysfs_driver *driver) -------------------------------------------------------------------------------- - -------------------------------------------------------------------------------- -Name: sysfs_open_driver - -Description: Given the name of the bus on which to look for, this function - locates a given driver and returns a sysfs_driver structure - corresponding to the requested device. - - NOTE: - 1. The sysfs_driver structure obtained upon successful return - from this function has to be closed by calling - sysfs_close_driver_by_name(). - -Arguments: const char *bus_name Bus on which to search - const char *drv_name Driver name to look for - -Returns: struct sysfs_driver * with success - NULL with error. Errno will be set with error, returning - - EINVAL for invalid arguments - -Prototype: struct sysfs_driver *sysfs_open_driver(const char *bus_name, - const char *drv_name) -------------------------------------------------------------------------------- - -------------------------------------------------------------------------------- -Name: sysfs_get_driver_module - -Description: Function takes a sysfs_driver structure and returns the module - that the driver is using. - -Arguments: struct sysfs_driver *drv Driver for which the module - details are required - -Returns: struct sysfs_module * with success - NULL with error. Errno will be set with error, returning - - EINVAL for invalid arguments - -Prototype: struct dlist *sysfs_get_driver_module - (struct sysfs_driver *drv) -------------------------------------------------------------------------------- - - -6.8 Module Functions --------------------- - -Modules are represented in sysfs under the /sys/module. Functions are provided -to open and close modules. - -------------------------------------------------------------------------------- -Name: sysfs_close_module - -Description: Closes and cleans up the sysfs_module structure - -Arguments: struct sysfs_module *module sysfs_module device to close - -Prototype: void sysfs_close_module(struct sysfs_module *module); -------------------------------------------------------------------------------- - -------------------------------------------------------------------------------- -Name: sysfs_open_module_path - -Description: Opens and populates the sysfs_module struct - -Arguments: const char *path path to the module to open - -Returns: struct sysfs_module * with success and NULL if error - -Prototype: struct sysfs_module *sysfs_open_module_path(const char *path); -------------------------------------------------------------------------------- - -------------------------------------------------------------------------------- -Name: sysfs_open_module - -Description: Opens specific module on a system - -Arguments: const char *name Name of the module to open - -Returns: struct sysfs_module * with success or NULL if error - -Prototype: struct sysfs_module *sysfs_open_module(const char *name); -------------------------------------------------------------------------------- - -------------------------------------------------------------------------------- -Name: sysfs_get_module_parms - -Description: Get modules list of parameters - -Arguments: sysfs_module whose parmameter list is required - -Returns: dlist of parameters on SUCCESS and NULL on error - -Prototype: struct dlist *sysfs_get_module_parms(struct sysfs_module *module); -------------------------------------------------------------------------------- -------------------------------------------------------------------------------- -Name: sysfs_get_module_sections - -Description: Get the set of sections for this module - -Arguments: sysfs_module whose list of sections is required - -Returns: dlist of sections on SUCCESS and NULL on error - -Prototype: struct dlist *sysfs_get_module_sections(struct sysfs_module *module); -------------------------------------------------------------------------------- - -------------------------------------------------------------------------------- -Name: sysfs_get_module_attributes - -Description: Get dlist of attributes for the requested sysfs_module - -Arguments: sysfs_module for which attributes are needed - -Returns: a dlist of attributes if exists, NULL otherwise - -Prototype: struct dlist *sysfs_get_module_attributes(struct sysfs_module *module); -------------------------------------------------------------------------------- - -------------------------------------------------------------------------------- -Name: sysfs_get_module_attr - -Description: searches module's attributes by name - -Arguments: module: to look through - name: name of the attribute - -Returns: sysfs_attribute reference with success or NULL with error - -Prototype: struct sysfs_attribute *sysfs_get_module_attr - (struct sysfs_module *module, const char *name); -------------------------------------------------------------------------------- - -------------------------------------------------------------------------------- -Name: sysfs_get_module_parm - -Description: searches module's parameters by name - -Arguments: sysfs_module: to look through - parm: parameter name - -Returns: sysfs_attribute on SUCCESS and NULL on error - -Prototype: struct sysfs_attribute *sysfs_get_module_parm - (struct sysfs_module *module, const char *parm); -------------------------------------------------------------------------------- - -------------------------------------------------------------------------------- -Name: sysfs_get_module_section - -Description: searches module's sections by name - -Arguments: sysfs_module: to look through - section: section name - -Returns: sysfs_attribute * on SUCCESS and NULL on error - -Prototype: struct sysfs_attribute *sysfs_get_module_section - (struct sysfs_module *module, const char *section); -------------------------------------------------------------------------------- - - -7 Dlists --------- - -Libsysfs uses (yet another) list implementation thanks to Eric J Bohm. - - -7.1 Navigating a dlist ----------------------- - -Some library functions return a dlist of devices/drivers/attributes, etc. -To navigate the list returned the macro "dlist_for_each_data" is to be used. - ------------------------------------------------------------------------------- -Function/Macro name: dlist_for_each_data - -Description: Walk the given list, returning a known data type/ - structure in each iteration. - -Arguments: struct dlist *list List pointer - data_iterator Data type/structure variable - contained in the list - datatype Data type/structure contained - in the list - -Returns: On each iteration, "data_iterator" will contain a list - element of "datatype" - -Usage example: The function sysfs_get_classdev_attributes() returns a - dlist of attributes. To navigate the list: - - struct sysfs_attribute *attr = NULL; - struct dlist *attrlist = NULL; - . - . - . - attrlist = sysfs_get_classdev_attributes - (struct sysfs_class_device *cdev) - if (attrlist != NULL) { - dlist_for_each_data(attrlist, attr, - struct sysfs_attribute) { - . - . - . - } - } -------------------------------------------------------------------------------- - - -7.2 Custom sorting using dlist_sort_custom() --------------------------------------------- - -As of release 1.2.0, libsysfs provides a new interface for custom sorting -of dlists. The API dlist_sort_custom() has been added for this purpose. -Applications that would like to define their own sorter function can now -make use of this API. - -The sorter function must conform to the following prototype: - - int compare(void *a, void*b) - -dlist_sort_custom() expects that the compare function will: - return >0 for a before b - return <0 for b before a - return 0 for a == b - -7.3 Custom filtering and sorting using dlist_filter_sort() ----------------------------------------------------------- - -From release 2.0.0, libsysfs provides a new interface for custom filtering -and sorting of dlists. This API is similar to scandir() system call. -Applications can call this API with the following arguments: the list, pointer -to the filter function, pointer to the sorter function as in -dlist_sort_custom. - -The filter function must conform to the following prototype: - - int filter(void *a) - -dlist_filter_sort expects that the filter function will: - return 0 for unwanted nodes - return 1 for required nodes - -8. Usage --------- - -Accessing devices through libsysfs is supposed to mirror accessing devices -in the filesystem it represents. Here's a typical order of operation: - - - get sysfs mount point - - "open" sysfs category, ie. bus, class, or device - - work with category - - "close" sysfs category - - -9. Testsuite ------------- - -From version 2.0.0 sysfsutils ships with a comprehensive testsuite. The -testsuite shipped as part of the "test" directory of the sysfsutils source -package, results in an executable "testlibsysfs". Some of the salient -features of the testsuite are: - -a. Tests _every_ API exported by the library. -b. Tests are performed for all possible combinations of input parameters. -c. Detailed output is provided for the correct case. -d. Facility to redirect output of the tests to a normal file. -e. Number of iterations of tests can be specified. - -The testsuite comes with its own configuration file "libsysfs.conf" in the -"test" directory. This file is used to generate a header file at the time -the tests are built. - -To use the testsuite: - -a. Modify the variables libsysfs.conf file to appropriate values for your - system. (The libsysfs.conf file contains comments describing what each - variable stands for and, in some cases, how to determine an appropriate - value for the system under test). - - -b. Build testsuite. - -c. Run the testsuite: - - testlibsysfs <number of iterations> <logfile> - -The default logfile is stdout. - -NOTE: If the libsysfs.conf file is changed, make sure to run "make clean" in -the test directory and then a "make" for the changes to take effect. - - -10. Conclusion --------------- - -Libsysfs is meant to provide a stable application programming interface to -sysfs. Applications can depend upon the library to access system devices -and functions exposed through sysfs. |