Tribblix: manual page: libdevinfo.3lib

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(4D). 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