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Intel
®
IXP45X and Intel
®
IXP46X Product Line of Network Processors—USB 2.0 Host Controller
Intel
®
IXP45X and Intel
®
IXP46X Product Line of Network Processors
Developer’s Manual
August 2006
412
Order Number: 306262-004US
following sections. The USB 2.0 host controller must be implemented as a multi-
function PCI device if the implementation includes companion controllers. The
companion host controllers’ function numbers must be less than the EHCI host
controller function number. The EHCI host controller must be a larger function number
with respect to the companion host controllers associated with this EHCI host
controller. If a PCI device implementation contains only an EHCI controller (i.e. no
companion controllers or other PCI functions), then the EHCI host controller must be
function zero, in accordance with the PCI Specification. The N_CC field in the Structural
Parameter register (HCSPARAMS) indicates whether the controller implementation
includes companion host controllers. When N_CC has a non-zero value there exists
companion host controllers. If N_CC has a value of zero, then the host controller
implementation does not include companion host controllers. If the host controller root
ports are exposed to attachment of full- or low-speed devices, the ports will always fail
the high-speed chirp during reset and the ports will not be enabled. System software
can notify the user of the illegal condition. This type of implementation requires a USB
2.0 hub be connected to a root port to provide full and low-speed device connectivity.
System software uses information in the host controller capability registers to
determine how the ports are routed to the companion host controllers. See
9.11.3, “HCSPARAMS – EHCI Compliant with Extensions” on page 370
.
9.14.2.1
Port Routing Control via EHCI Configured (CF) Bit
Each port in the USB 2.0 host controller can be routed either to a single companion
host controller or to the EHCI host controller. The port routing logic is controlled by two
mechanisms in the EHCI HC: a host controller global flag and per-port control. The
Configured Flag (CF) bit (defined in
Section 9.12.8, “BURSTSIZE” on page 380
), is used
to globally set the policy of the routing logic. Each port register has a Port Owner
control bit which allows the EHCI Driver to explicitly control the routing of individual
ports. Whenever the CF bit transitions from a zero to a one (this transition is only
available under program control) the port routing unconditionally routes all of the port
registers to the EHCI HC (all Port Owner bits go to zero). While the CF-bit is a one, the
EHCI Driver can control individual ports' routing via the Port Owner control bit.
Likewise, whenever the CF bit transitions from a one to a zero (as a result of Aux power
application, HCRESET, or software writing a zero to CF-bit), the port routing
unconditionally routes all of the port registers to the appropriate companion HC. The
default value for the EHCI HC’s CF bit (after Aux power application or HCRESET) is zero.
Table 168, “Default Port Routing Depending on EHCI HC CF Bit” on page 412
summarizes the default routing for all the ports, based on the value of the EHCI HC’s
CF bit.
The view of the port depends on the current owner. A Universal or Open companion
host controller will see port register bits consistent with the appropriate specification.
Port bit definitions that are required for EHCI host controllers are not visible to
companion host controllers.
Table 168.
Default Port Routing Depending on EHCI HC CF Bit
HS CF
Bit
Default
Port
Ownership
Explanation
0B
Companion
HCs
The companion host controllers own the ports and only Full- and Low-speed devices
are supported in the system. The ports behave only as Full- and Low-speed ports in
this configuration
1B
EHCI HC
The EHCI host controller has default ownership overall of the ports. The routing logic
inhibits device connect events from reaching the companion HCs' port status and
control registers when the port owner is the EHCI HC.The EHCI HC has access to the
additional port status and control bits defined in this specification. The EHCI HC can
temporarily release control of the port to a companion HC by setting the PortOwner
bit in the PORTSC register to a one.