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usb(7)									usb(7)

NAME    [Toc]    [Back]

     usb - Irix	USB subsystem

DESCRIPTION    [Toc]    [Back]

     This page documents the Irix USB implementation for Onyx3.

     The SN1 system Ibrick incorporates	a USB host controller as part of the
     baseio device set.	 There are two usb ports, on one usb controller.

   Device Topology    [Toc]    [Back]
     The USB device topology is	exported through a subtree in the hardware
     graph.  The device	topology format	is subject to change over releases as
     the need arises, so it should not be relied on by scripts.	 Each usb
     driver (eg. keyboard, mouse) should export	it's own namespace that	can be
     relied on.

     Usb hwgraph paths are of the form:


     Where <slot> is 5 for the Ibrick internal usb controller.	<port_path> is
     a '/' separated sequence of usb hub port numbers.	Ports having a common
     parent belong to the same usb hub.	 Port components separated by a	'/'
     are connected by a	hub.  For example:


     refers to port 1 of the usb controller, or	Root Hub in USB	terminology.


     refers to port 2 of the hub which is plugged into port 1 of the Root Hub.

     If	a non-hub device is plugged into a port	(and there is a	driver for
     that device), a driver-specific path will be hung off of the port that
     the device	is plugged into.  In the example:


     a driver has detected a keyboard device plugged into hub port 3, and a
     mouse plugged into	hub port 4.  The hub in	this example is	plugged	into
     the Root Hub port 2.

   USB Topology	Rules
	  The following	rules are enforced by the usb subsystem:

	  - The	maximum	depth from root	hub to end device cannot exceed	7,
	    where the root hub (ie. controller)	counts as 1.  Stated
	    another way, you can have 5	usb hubs between the root hub and
	    an end device.

									Page 1

usb(7)									usb(7)

	 - All hubs in a path must be self-powered with	the exception of
	    the	one closest to the end device.

	  - Devices plugged into a port	of a bus-powered hub must be
	    classified as low-power devices (max 100ma draw).

   Hub Driver    [Toc]    [Back]
     The Irix USB infrastructure implements the	driver for USB hubs.  Hubs
     conforming	to the USB 1.1 spec are	supported.

   Hot Plug    [Toc]    [Back]
     The Irix USB implemtation supports	hot plugging and unplugging of USB
     devices, within the constraints of	the USB	topology rules.

     A device that is hot plugged will be initialized to a default state by
     the usb subsystem,	and then the appropriate driver	(if any) will be
     called to do further driver specific initialization.  Device
     initialization errors will	generally be logged to the console, and	the
     device will not be	accessble.

     A device that is unplugged	will have its entry removed from the USB
     hwgraph namespace.	 It is up to the individual drivers to do any driverspecific
 cleanup at unplug	time.

   Reset    [Toc]    [Back]
     There is no general usb administrative command.  If a device needs	to be
     reset, it should be unplugged, and	replugged.

NOTES    [Toc]    [Back]

     The SGI USB implemtation is a partial implementation, intended to provide
     support for selected keyboards and	mice (see usbinput(7)) for Onyx3.
     Currently there is	no administrative command for individual device
     control, and there	is no support for devices other	than keyboard/mouse.

     Likewise, the usb infrastructure provides no published api	for the
     implentation of new usb drivers.

     Only controllers conforming to the	OpenHCI	spec are supported.

SEE ALSO    [Toc]    [Back]

     usbinput(7), Universal Serial Bus Specification rev 1.1, OpenHCI Open
     Host Controller Interface Specification for USB rev 1.0a

									PPPPaaaaggggeeee 2222
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