LIBDEVINFO(3LIB) Interface Libraries LIBDEVINFO(3LIB)


NAME


libdevinfo - device information library

SYNOPSIS


cc [ flag... ] file... -ldevinfo [ library... ]
#include <libdevinfo.h>


DESCRIPTION


Functions in this library access device configuration information.


Device configuration data is organized as a tree of device nodes, defined
as di_node_t in the libdevinfo interfaces. Each di_node_t represents a
physical or logical (pseudo) device. The types of data associated with
device nodes are:

o data defined for all device nodes (attributes)

o data defined for all multipath path nodes

o data defined for all minor node data

o properties specific to nodes


All device nodes have a set of common attributes, such as a node name, an
instance number, and a driver binding name. Common device node attributes
are accessed by calling interfaces listed on the
di_binding_name(3DEVINFO) manual page. Each device node also has a
physical path, which is accessed by calling di_devfs_path(3DEVINFO).


Properties provide device specific information for device configuration
and usage. Properties can be defined by software (di_prop_t) or by
firmware (di_prom_prop_t). One way to access each di_prop_t is to make
successive calls to di_prop_next(3DEVINFO) until DI_PROP_NIL is returned.
For each di_prop_t, use interfaces on the di_prop_bytes(3DEVINFO) manual
page to obtain property names and values. Another way to access these
properties is to call di_prop_lookup_bytes(3DEVINFO) to find the value of
a property with a given name. Accessing a di_prom_prop_t is similar to
accessing a di_prop_t, except that the interface names start with
di_prom_prop and additional calls to di_prom_init(3DEVINFO) and
di_prom_fini(3DEVINFO) are required.


Minor nodes contain information exported by the device for creating
special files for the device. Each device node has 0 or more minor nodes
associated with it. A list of minor nodes (di_minor_t) can be obtained by
making successive calls to di_minor_next(3DEVINFO) until DI_MINOR_NIL is
returned. For each minor node, di_minor_devt(3DEVINFO) and related
interfaces are called to get minor node data.


In some configurations, multipath device access via a virtual host
controller interface (vHCI) abstraction is possible. An example of a
driver using this abstraction is scsi_vhci(7D). In such cases, devices
are not directly represented as children of their physical host
controller interface (pHCI) bus adapter. Instead, devices have an
identity-oriented representation as a child of a vHCI. All paths leading
to the same identity are represented by a common child endpoint of the
vHCI called the "client" device node. The vHCI virtualizes access among
the underlying pHCI physical paths. The underlying connection between
vHCI-managed client endpoints and the pHCI paths to that endpoint is
represented by a class of nodes called "path" nodes (di_path_t).


Each path node is associated with two device nodes: its pHCI device node,
and its client device node. A list of paths associated with a specific
pHCI device node can be obtained using di_path_phci_next_path(3DEVINFO),
and a list of paths associated with a specific client device node can be
obtained using di_path_client_next_path(3DEVINFO). These functions return
DI_PATH_NIL when the end of the list of path nodes is reached.


For each path node, di_path_state(3DEVINFO) and related interfaces are
called to get path node data.


Using libdevinfo involves three steps:

o Creating a snapshot of the device tree

o Traversing the device tree to get information of interest

o Destroying the snapshot of the device tree


A snapshot of the device tree is created by calling di_init(3DEVINFO) and
destroyed by calling di_fini(3DEVINFO). An application can specify the
data to be included in the snapshot (full or partial tree, include or
exclude properties and minor nodes) and get a handle to the root of the
device tree. See di_init(3DEVINFO) for details. The application then
traverses the device tree in the snapshot to obtain device configuration
data.


The device tree is normally traversed through parent-child-sibling
linkage. Each device node contains references to its parent, its next
sibling, and the first of its children. Given the di_node_t returned from
di_init(), one can find all children by first calling
di_child_node(3DEVINFO), followed by successive calls to
di_sibling_node(3DEVINFO) until DI_NODE_NIL is returned. By following
this procedure recursively, an application can visit all device nodes
contained in the snapshot. Two interfaces,The di_walk_node(3DEVINFO) and
di_walk_minor(3DEVINFO) functions are provided to facilitate device tree
traversal. The di_walk_node() function visits all device nodes and
executes a user-supplied callback function for each node visited. The
di_walk_minor() function does the same for each minor node in the device
tree.


An alternative way to traverse the device tree is through the per-driver
device node linkage. Device nodes contain a reference to the next device
node bound to the same driver. Given the di_node_t returned from
di_init(), an application can find all device nodes bound to a driver by
first calling di_drv_first_node(3DEVINFO), followed by successive calls
to di_drv_next_node(3DEVINFO) until DI_NODE_NIL is returned. Traversing
the per-driver device node list works only when the snapshot includes all
device nodes.


See di_init(3DEVINFO) for examples of libdevinfo usage. See Writing
Device Drivers for information about Solaris device configuration.

INTERFACES


The shared object libdevinfo.so.1 provides the public interfaces defined
below. See Intro(3) for additional information on shared object
interfaces.


di_binding_name di_bus_addr
di_child_node di_compatible_names
di_devfs_minor_path di_devfs_path
di_devfs_path_free di_devid
di_driver_major di_driver_name
di_driver_ops di_drv_first_node
di_drv_next_node di_fini
di_init di_instance
di_link_next_by_lnode di_link_next_by_node
di_link_private_get di_link_private_set
di_link_spectype di_link_to_lnode
di_lnode_devinfo di_lnode_devt
di_lnode_name di_lnode_next
di_lnode_private_get di_lnode_private_set
di_minor_devt di_minor_name
di_minor_next di_minor_nodetype
di_minor_private_get di_minor_private_set
di_minor_spectype di_minor_type
di_node_name di_node_private_get
di_node_private_set di_nodeid
di_parent_node di_path_bus_addr
di_path_client_devfs_path di_path_client_next_path
di_path_client_node di_path_devfs_path
di_path_instance di_path_node_name
di_path_phci_next_path di_path_phci_node
di_path_prop_bytes di_path_prop_int64s
di_path_prop_ints di_path_prop_len
di_path_prop_lookup_bytes di_path_prop_lookup_int64s
di_path_prop_lookup_ints di_path_prop_lookup_strings
di_path_prop_name di_path_prop_strings
di_path_prop_next di_path_prop_type
di_path_state di_prom_fini
di_prom_init di_prom_prop_data
di_prom_prop_lookup_bytes di_prom_prop_lookup_ints
di_prom_prop_lookup_strings di_prom_prop_name
di_prom_prop_next di_prop_bytes
di_prop_devt di_prop_int64
di_prop_ints di_prop_lookup_bytes
di_prop_lookup_int64 di_prop_lookup_ints
di_prop_lookup_strings di_prop_name
di_prop_next di_prop_strings
di_prop_type di_sibling_node
di_state di_walk_link
di_walk_lnode di_walk_minor
di_walk_node


EXAMPLES


Example 1: Information accessible through libdevinfo interfaces




The following example illustrates the kind of information accessible
through libdevinfo interfaces for a device node representing a hard disk
(sd2):


Attributes
node name: sd
instance: 2
physical path: /sbus@1f,0/espdma@e,8400000/esp@e,8800000/sd@2,0

Properties
target=2
lun=0

Minor nodes
(disk partition /dev/dsk/c0t2d0s0)
name: a
dev_t: 0x0080010 (32/16)
spectype: IF_BLK (block special)
(disk partition /dev/rdsk/c0t2d0s2)
name: c,raw
dev_t: 0x0080012 (32/18)
spectype: IF_CHR (character special)


FILES


/lib/libdevinfo.so.1

shared object


/usr/lib/64/libdevinfo.so.1

64-bit shared object


ATTRIBUTES


See attributes(5) for descriptions of the following attributes:


+--------------------+-----------------+
| ATTRIBUTE TYPE | ATTRIBUTE VALUE |
|Interface Stability | Committed |
+--------------------+-----------------+
|MT-Level | Safe |
+--------------------+-----------------+

SEE ALSO


pvs(1), devlinks(1M), prtconf(1M), Intro(3), di_binding_name(3DEVINFO),
di_child_node(3DEVINFO), di_devfs_path(3DEVINFO), di_init(3DEVINFO),
di_minor_devt(3DEVINFO), di_minor_next(3DEVINFO),
di_path_bus_addr(3DEVINFO), di_path_client_next_path(3DEVINFO),
di_path_prop_bytes(3DEVINFO), di_path_prop_lookup_bytes(3DEVINFO),
di_path_prop_next(3DEVINFO), di_prom_init(3DEVINFO),
di_prop_bytes(3DEVINFO), di_prop_lookup_bytes(3DEVINFO),
di_prop_next(3DEVINFO), di_walk_minor(3DEVINFO), di_walk_node(3DEVINFO),
attributes(5)


Writing Device Drivers


May 15, 2008 LIBDEVINFO(3LIB)