![Intel IXP45X Developer'S Manual Download Page 487](http://html1.mh-extra.com/html/intel/ixp45x/ixp45x_developers-manual_2073092487.webp)
Intel
®
IXP45X and Intel
®
IXP46X Product Line of Network Processors
August 2006
Developer’s Manual
Order Number: 306262--, Revision: 004US
487
USB 2.0 Host Controller—Intel
®
IXP45X and Intel
®
IXP46X Product Line of Network Processors
the system, the transaction translator function normally associated with a high speed
hub has been implemented within the DMA and Protocol engine blocks. The embedded
transaction translator function is an extension to EHCI interface, but makes use of the
standard data structures and operational models that exist in the EHCI specification to
support full and low speed devices.
9.15.1.1
Capability Registers
The following additions have been added to the capability registers to support the
embedded Transaction Translator Function:
• N_TT added to
Table 131, “HCSPARAMS – Host Control Structural Parameters” on
.
• N_PTT added to
Table 131, “HCSPARAMS – Host Control Structural Parameters” on
.
Section 9.11.3, “HCSPARAMS – EHCI Compliant with Extensions” on page 370
with
extensions for usage information.
9.15.1.2
Operational Registers
The following additions have been added to the operational registers to support the
embedded TT:
• A new register.
• Addition of two-bit Port Speed (PSPD) to the PORTSCx register.
9.15.1.3
Discovery
In a standard EHCI controller design, the EHCI host controller driver detects a Full
speed (FS) or Low speed (LS) device by noting if the port enable bit is set after the port
reset operation. The port enable will only be set in a standard EHCI controller
implementation after the port reset operation and when the host and device negotiate
a High-Speed connection (i.e. Chirp completes successfully).
Since this controller has an embedded Transaction Translator, the port enable will
always be set after the port reset operation regardless of the result of the host device
chirp result and the resulting port speed will be indicated by the PSPD field in PORTSCx.
Therefore, the standard EHCI host controller driver requires an alteration to handle
directly connected Full and Low speed devices or hubs.
The change is a fundamental one in that is summarized in the next table.
Table 187.
Standard EHCI vs. EHCI with Embedded Transaction Translator
Standard EHCI
EHCI with Embedded Transaction Translator
After port enable bit is set following a connection and
reset sequence, the device/hub is assumed to be HS.
After port enable bit is set following a connection and reset
sequence, the device/hub speed is noted from PORTSCx.
FS and LS devices are assumed to be downstream from
a HS hub thus, all port-level control is performed
through the Hub Class to the nearest hub.
FS and LS device can be either downstream from a HS hub or
directly attached. When the FS/LS device is downstream from a HS
hub, then port-level control is done using the Hub Class through the
nearest hub. When a FS/LS device is directly attached, then port-
level control is accomplished using PORTSCx.
FS and LS devices are assumed to be downstream from
a HS hub with HubAddr=X. [where HubAddr > 0 and
HubAddr is the address of the hub where the bus
transitions from HS to FS/LS (that is, Split target
hub)]
FS and LS device can be either downstream from a HS hub with
HubAddr = X [HubAddr > 0] or directly attached [where HubAddr
= 0 and HubAddr is the address of the Root hub where the
bus transitions from HS to FS/LS (that is, Split target hub is
the root hub)]