Universal Host Controller Interface

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Revision as of 20:56, 27 May 2014 by osdev>Ednutting (Added link to copy of UHCI spec and corrected PCI Configuration space I/O Port Base Address information. Originally it incorrectly stated that base address could be found in BAR0. It is actually found in BAR4 (as per spec).)
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Universal Host Controller Interface (UHCI) was created by Intel as an implementation of the USB 1.0 host controller interface. Along with OHCI, it makes up the USB 1.0 standard.

Technical Details

The UHCI specification defines a set of I/O mapped registers that allow communication between the controller and the operating system. The base address for these registers can be found by searching the PCI controller for a specific VendorID/DeviceID combination, or for a specific ClassID/SubclassID/Interface combination. All UHCI PCI controllers will have a Class ID of 0x0C, a Subclass ID of 0x03, and an Interface value of 0x00. The PCI Configuration space for this device will contain the I/O port address information in BAR4. This may be different from other standards such as OHCI or EHCI.

I/O Registers

Offset (Hex) Name Description
00 USBCMD Usb Command
02 USBSTS Usb Status
04 USBINTR Usb Interrupt Enable
06 FRNUM Frame Number
08 FRBASEADD Frame List Base Address
0C SOFMOD Start Of Frame Modify
10 PORTSC1 Port 1 Status/Control
12 PORTSC2 Port 2 Status/Control


References

  1. Copy of Intel UHCI standard from NetBSD.org
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