Binding Client Drivers
This section discusses binding a driver to a device. It discusses compatible device
names for devices with single interfaces and devices with multiple interfaces.
How USB Devices Appear to the System
A USB device can support multiple configurations. Only one configuration is active at
any given time. The active configuration is called the current configuration.
A configuration can have more than one interface, possibly with intervening interface-associations that
group two or more interfaces for a function. All interfaces of a configuration
are active simultaneously. Different interfaces might be operated by different device drivers.
An interface can represent itself to the host system in different ways by
using alternate settings. Only one alternate setting is active for any given interface.
Each alternate setting provides device access through endpoints. Each endpoint has a specific
purpose. The host system communicates with the device by establishing a communication channel
to an endpoint. This communication channel is called a pipe.
USB Devices and the Solaris Device Tree
If a USB device has one configuration, one interface, and device
class zero, the device is represented as a single device node. If a USB device
has multiple interfaces, the device is represented as a hierarchical device structure. In
a hierarchical device structure, the device node for each interface is a child
of the top-level device node. An example of a device with multiple interfaces
is an audio device that presents simultaneously to the host computer both an
audio control interface and an audio streaming interface. The audio control interface and
the audio streaming interface each could be controlled by its own driver.
Compatible Device Names
The Solaris software builds an ordered list of compatible device names for USB
binding based on identification information kept within each device. This information includes device
class, subclass, vendor ID, product ID, revision, and protocol. See https://www.usb.org/ for a list
of USB classes and subclasses.
This name hierarchy enables binding to a general driver if a more
device-specific driver is not available. An example of a general driver is a
class-specific driver. Device names that begin with usbif designate single interface devices. See Example 20-1
for examples. The USBA 2.0 framework defines all compatible names for a device. Use
the prtconf command to display these device names, as shown in Example 20-2.
The following example shows an example of compatible device names for a USB
mouse device. This mouse device represents a combined node entirely operated by a
single driver. The USBA 2.0 framework gives this device node the names shown in
the example, in the order shown.
Example 20-1 USB Mouse Compatible Device Names
1. 'usb430,100.102' Vendor 430, product 100, revision 102
2. 'usb430,100' Vendor 430, product 100
3. 'usbif430,class3.1.2' Vendor 430, class 3, subclass 1, protocol 2
4. 'usbif430,class3.1' Vendor 430, class 3, subclass 1
5. 'usbif430,class3' Vendor 430, class 3
6. 'usbif,class3.1.2' Class 3, subclass 1, protocol 2
7. 'usbif,class3.1' Class 3, subclass 1
8. 'usbif,class3' Class 3
Note that the names in the above example progress from the most specific
to the most general. Entry 1 binds only to a particular revision of
a specific product from a particular vendor. Entries 3, 4, and 5 are
for class 3 devices manufactured by vendor 430. Entries 6, 7, and 8 are
for class 3 devices from any vendor. The binding process looks for a match
on the name from the top name down. To bind, drivers must be
added to the system with an alias that matches one of these names.
To get a list of compatible device names to which to bind
when you add your driver, check the compatible property of the device in the
output from the prtconf -vp command.
The following example shows compatible property lists for a keyboard and a mouse.
Use the prtconf -D command to display the bound driver.
Example 20-2 Compatible Device Names Shown by the Print Configuration Command
# prtconf -vD | grep compatible
compatible: 'usb430,5.200' + 'usb430,5' + 'usbif430,class3.1.1'
+ 'usbif430,class3.1' + 'usbif430,class3' + 'usbif,class3.1.1' +
'usbif,class3.1' + 'usbif,class3'
compatible: 'usb2222,2071.200' + 'usb2222,2071' +
'usbif2222,class3.1.2' + 'usbif2222,class3.1' + 'usbif2222,class3' +
'usbif,class3.1.2' + 'usbif,class3.1' + 'usbif,class3'
Use the most specific name you can to more accurately identify a driver
for a device or group of devices. To bind drivers written for a
specific revision of a specific product, use the most specific name match possible.
For example, if you have a USB mouse driver written by vendor 430 for
revision 102 of their product 100, use the following command to add that driver to
add_drv -n -i '"usb430,100.102"' specific_mouse_driver
To add a driver written for any USB mouse (class 3, subclass
1, protocol 2) from vendor 430, use the following command:
add_drv -n -i '"usbif430,class3.1.2"' more_generic_mouse_driver
If you install both of these drivers and then connect a compatible
device, the system binds the correct driver to the connected device. For example, if
you install both of these drivers and then connect a vendor 430,
model 100, revision 102 device, this device is bound to specific_mouse_driver. If you connect
a vendor 430, model 98 device, this device is bound to more_generic_mouse_driver.
If you connect a mouse from another vendor, this device also is bound
to more_generic_mouse_driver. If multiple drivers are available for a specific device, the driver
binding framework selects the driver with the first matching compatible name in the
compatible names list.
Devices With Multiple Interfaces
Composite devices are devices that support multiple interfaces. Composite devices have a list of
compatible names for each interface. This compatible names list ensures that the best
available driver is bound to the interface. The most general multiple interface entry
For a USB audio composite device, the compatible names are as follows:
1. 'usb471,101.100' Vendor 471, product 101, revision 100
2. 'usb471,101' Vendor 471, product 101
3. 'usb,device' Generic USB device
The name usb,device is a compatible name that represents any whole USB device.
The usb_mid(7D) driver (USB multiple-interface driver) binds to the usb,device device node if
no other driver has claimed the whole device. The usb_mid driver creates a child
device node for each interface of the physical device. The usb_mid driver
also generates a set of compatible names for each interface. Each of these
generated compatible names begins with usbif. The system then uses these generated compatible
names to find the best driver for each interface. In this way, different
interfaces of one physical device can be bound to different drivers.
For example, the usb_mid driver binds to a multiple-interface audio device through the
usb,device node name of that audio device. The usb_mid driver then creates interface-specific device
nodes. Each of these interface-specific device nodes has its own compatible name list.
For an audio control interface node, the compatible name list might look like
the list shown in the following example.
Example 20-3 USB Audio Compatible Device Names
1. 'usbif471,101.100.config1.0' Vend 471, prod 101, rev 100, cnfg 1, iface 0
2. 'usbif471,101.config1.0' Vend 471, product 101, config 1, interface 0
3. 'usbif471,class1.1.0' Vend 471, class 1, subclass 1, protocol 0
4. 'usbif471,class1.1' Vend 471, class 1, subclass 1
5. 'usbif471,class1' Vend 471, class 1
6. 'usbif,class1.1.0' Class 1, subclass 1, protocol 0
7. 'usbif,class1.1' Class 1, subclass 1
8. 'usbif,class1' Class 1
Use the following command to bind a vendor-specific, device-specific client driver named vendor_model_audio_usb
to the vendor-specific, device-specific configuration 1, interface 0 interface compatible name shown in Example 20-3.
add_drv -n -i '"usbif471,101.config1.0"' vendor_model_audio_usb
Use the following command to bind a class driver named audio_class_usb_if_driver to
the more general class 1, subclass 1 interface compatible name shown in Example 20-3:
add_drv -n -i '"usbif,class1.1"' audio_class_usb_if_driver
Use the prtconf -D command to show a list of devices and
their drivers. In the following example, the prtconf -D command shows that the usb_mid
driver manages the audio device. The usb_mid driver is splitting the audio device into
interfaces. Each interface is indented under the audio device name. For each interface
shown in the indented list, the prtconf -D command shows which driver
manages the interface.
audio, instance #0 (driver name: usb_mid)
sound-control, instance #2 (driver name: usb_ac)
sound, instance #2 (driver name: usb_as)
input, instance #8 (driver name: hid)
Devices With Interface-Association Descriptors
If the device includes an interface-association descriptor, the device tree can be parsed
at the following three levels:
The usb_mid(7D) USB multi-interface driver binds to device level nodes of a composite device if no vendor or class-specific driver is available.
A client driver is bound to the interface association nodes.
The usb_ia(7D) USB interface association driver is bound by default if no client driver is found. Then client drivers can be bound to the interface level of this interface association.
The usb_mid driver creates an ia (interface association) node for each ia. The
compatible names of ia nodes generally begin with usbia. The name usb,ia
is a compatible name that represents any ia as the tail of the
compatible names. The usb_ia driver is bound to an ia node if no
other driver has claimed this ia. The usb_ia driver creates a child
node for each interface. An interface node as the child node of an
ia node has the same properties with an interface node as the child
of a device node.
Example 20-4 USB Video Interface Association Compatible Names
1. 'usbia46d,8c9.5.config1.0' vend 46d, prod 8c9, rev 5, cnfg 1, first_if_in_ia 0
2. 'usbia46d,8c9.config1.0' vend 46d, prod 8c9, cnfg 1, first_if_in_ia 0
3. 'usbia46d,classe.3.0' vend 46d, class e, subclass 3, protocol 0
4. 'usbia46d,classe.3' vend 46d, class e, subclass 3
5. 'usbia46d,classe' vend 46d, class e
6. 'usbia,classe.3.0' class e, subclass 3, protocol 0
7. 'usbia,classe.3' class e, subclass 3
8. 'usbia,classe' class e
9. 'usb,ia' by default
Use the following command to bind a vendor-specific, device-specific client driver named vendor_model_video_usb
to the vendor-specific, device-specific configuration 1, first_if_in_ia 0 compatible name shown in Example 20-4:
add_drv -n -i '"usbia46d,8c9.config1.0"' vendor_model_video_usb
Use the following command to bind a class driver named video_class_usb_ia_driver to
the more general class e compatible names shown in Example 20-4:
add_drv -n -i '"usbia,classee"' video_class_usb_ia_driver
In the following example, the prtconf -D command shows a device tree of a
webcam with ia of video and audio. The usb_mid driver manages the
device and creates two ia respectively for video and audio. A video driver usbvc
is bound to the video ia, and audio drivers are bound to the
interface of the audio ia.
miscellaneous, instance #28 (driver name: usb_mid)
video, instance #24 (driver name: usbvc)
audio, instance #30 (driver name: usb_ia)
sound-control, instance #38 (driver name: usb_ac)
sound, instance #47 (driver name: usb_as)
Checking Device Driver Bindings
The file /etc/driver_aliases contains entries for the bindings that already exist on a
system. Each line of the /etc/driver_aliases file shows a driver name, followed
by a space, followed by a device name. Use this file to check
existing device driver bindings.
Note - Do not edit the /etc/driver_aliases file manually. Use the add_drv(1M) command to establish a
binding. Use the update_drv(1M) command to change a binding.