TUSB9261

www.ti.com

SLLSE67B

– MARCH 2011 – REVISED MAY 2011

4

OPERATION

4.1

General Functionality

The TUSB9261 ROM contains boot code that executes after a global reset which performs the initial

configuration required to load a firmware image from an attached SPI flash memory to local RAM. In the

absence of an attached SPI flash memory or a valid image in the SPI flash memory, the firmware will idle

and wait for a connection from a USB host through its HID interface which is also configured from the boot

code. The latter can be accomplished using a custom application or driver to load the firmware from a file

resident on the host system.

Once the firmware is loaded it configures the SATA advanced host controller interface host bus adapter

(AHCI) and the USB device controller. In addition, the configuration of the AHCI includes a port reset

which initiates an out of band (OOB) TX sequence from the AHCI link layer to determine if a device is

connected, and if so negotiate the connection speed with the device (3.0 Gbps or 1.5 Gbps).

The configuration of the USB device controller includes creation of the descriptors, configuration of the

device endpoints for support of UASP and USB mass storage class bulk-only transport (BOT), allocation

of memory for the transmit request blocks (TRBs), and creation of the TRBs necessary to transmit and

receive packet data over the USB. In addition, the firmware provides any other custom configuration

required for application specific implementation, for example a HID interface for user initiated backup.

After USB device controller configuration is complete, if a SATA device was detected during the AHCI

configuration the firmware connects the device to the USB bus when VBUS is detected. According to the

USB 3.0 specification, the TUSB9261 will initially try to connect at SuperSpeed USB, if successful it will

enter U0; otherwise, after the training time out it will enable the DP pull up and connect as a USB 2.0

high-speed or full-speed device depending on the speed supported by host or hub port.

When connected, the firmware presents the BOT interface as the primary interface and the UASP

interface as the secondary interface. If the host stack is UASP aware, it can enable the UASP interface

using a SET_INTERFACE request for alternate interface 1.

Following speed negotiation, the device should transmit a device to host (D2H) FIS with the device

signature. This first D2H FIS is received by the link layer and copied to the port signature register. When

firmware is notified of the device connection it queries the device for capabilities using the IDENTIFY

DEVICE command. Firmware then configures the device as appropriate for its interface and features

supported, for example an HDD that supports native command queuing (NCQ).

Copyright

© 2011, Texas Instruments Incorporated

OPERATION

9

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Product Folder Link(s): TUSB9261