USB HOST DRIVER V03 Freescale Semiconductor / Motorola, USB HOST DRIVER V03 Datasheet - Page 12

• Manufacturer Part Number: USB HOST DRIVER V03
• Description: USB Host Driver v03
• Manufacturer: Freescale Semiconductor / Motorola

2. Driver Model.
2.1. Driver Model Overview.
The MOTUSB Driver is based on the Windows Driver Model (WDM) architecture. The
latest Microsoft Windows operating systems family has begun USB support in WDM.
They include USB Device Drivers for hubs, Host controllers and some Device classes
(audio, mass-storage, HID, etc.). As well as built-in software components, these systems
provide a programming interface for USB Device Drivers, called Universal Serial Bus
Driver Interface (USBDI). However USBDI can only be used by kernel-mode
components (Drivers), and none of the USB functionality is available in user-mode.
2.2. USB Driver Stack.
All USB Device Drivers in WDM are USBDI Client Drivers. WDM Client Drivers are
technically layered and organized as a Driver stack. A USB Client Driver overlays the
Drivers USBD.SYS, USBHUB.SYS, and either UHCD.SYS or OPENHCI.SYS. The
relationship between these Drivers is illustrated in Figure 2-1. The USB Client Drivers
call USBD.SYS to perform the Device configuration and perform the various transfer
types. MOTUSB handles the Device configuration calls and the details of communication
with the bus Drivers. However, it is of interest to know something more about how
communication occurs between the Client Driver and the bus Drivers.
M
Kernel mode
User mode
Hardware
PRELIMINARY—SUBJECT TO CHANGE WITHOUT NOTICE
USB Bus Driver
(USBD.SYS)
UHCI Hub Driver
(UHCD.SYS)
USB Driver Interface (USBDI)
Fig 2.1 USB Stack
Driver Model.
MOTUSB Client Driver
USB Host Controller
Win32 Application
(MOTUSB.SYS)
Open HCI Hub Driver
(OPENHCI.SYS)
USB Hub Driver
(USBHUB.SYS)
2-1