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From: <Brad.Hards@dao.defence.gov.au>
To: linux-usb@suse.com
Date: Tue, 10 Aug 1999 16:19:33 +1000
Subject: [linux-usb] HOWTO-usb-0.6 [23K]
I think I have a high volume web-site coming online. I'll post a link when I
get it
sorted. So just a text version this time. I still need some words from someone
with
a EZUSB setup, and I am still trying to get my USB Zip drive to stop oopsing
the
kernel (trying the root hub tonight....)
Brad
-------------------------------------
How to get USB devices working under Linux
Brad Hards
$Revision: 0.6 $
This document is an early draft of a step-by-step guide to getting USB
devices working on a Linux system
_________________________________________________________________
Basic USB Configuration
You need a late version kernel. Kernel versions 2.2.7 and later
contain the USB code. You should, in an ideal world, be running the
current 2.3.x kernel, ideally with any pre-patches for the next
kernel. It is possible to use the 2.3.x USB code with a 2.2.x kernel -
see later in this document for details. USB code is in fairly early
development, so the changes between each version (and the bugs) tend
to change fairly fast. Support on the mailing list for anything except
the lastest version is scant at best.
The mailing list is <[1]linux-usb@suse.com>. To subscribe, send a mail
message to <[2]majordomo@suse.com> with content of subscribe
linux-usb. If you want to stop getting mailing list content, send a
mail message to <[3]majordomo@suse.com> with content of unsubscribe
linux-usb.
You need to configure USB into your kernel. Use of make menuconfig is
recommended. Under USB drivers - not for the faint of heart , you need
to select Support for USB (EXPERIMENTAL!) . You also need to select
one of UHCI (intel PIIX4 and others) support, OHCI (compaq and some
others) support or OHCI-HCD (other OHCI opt. Virt. Root Hub) support.
Use of more than one of UHCI, OHCI, and OHCI-HCD at the same time is
not expected to fully work (UHCI might work). Which one you select is
dependent on what kind of motherboard or adapter you have. Intel and
Via motherboards are UHCI. Compaq and NEC motherboards, iMacs and any
adapter using Opti chips (just about all of them) are OHCI, and you
can use OHCI or OHCI-HCD, at your option. If you do not know what kind
of controller to choose, check your motherboard documentation. You can
als look at /proc/pci for a hint - if the USB entry is of the form
0xHHHH, where HHHH are hex digits (e.g. something like I/O at 0xe400),
then it is UHCI. If it is of the form 32 bit memory at 0xHH000000,
where HH are hex digits (e.g. something like 32 bit memory at
0xee000000), then it is OHCI. Failing that, just try one.
You also need to select whichever devices you want to use, for example
USB mouse support for a USB mouse, USB keyboard support for a USB
keyboard, USB hub support for a hub, USB Abstract Control Model
support for a POTS or ISDN modem, Preliminary USB Printer support for
a USB printer, USB SCSI Support for mass storage devices, and EZUSB
Firmware downloader for downloading into an Anchor Chips USB
microcontroller kit. You should be able to use modules, kernel only,
or split modules and kernel code. I strongly recommend selecting hub
support, although it is not strictly needed if you are only plugging
devices into the root hub.
USB audio parsing support does not work at this time. Devices not
listed in this document are not working at the time of writing,
although developers are always welcome to contribute to the current
codebase.
If you want to use a stable kernel (2.2.x), you can replace the code
in the drivers/usb directory with the code from a developmental kernel
(2.3.x). You will need to uncomment the line in arch/i386/config.in
that says:
# source drivers/usb/Config.in
. Other architectures will need something similar. You also need to
add a few extra definitions near the top of the drivers/usb/usb.h :
#if LINUX_VERSION_CODE < 0x020300
#define DECLARE_WAIT_QUEUE_HEAD(w) struct wait_queue *w = NULL
#define DECLARE_WAITQUEUE(w,c) struct wait_queue w = {(c), NULL}
#define wait_queue_head_t struct wait_queue *
#define init_waitqueue_head(w) *(w) = 0
#define DECLARE_MUTEX_LOCKED(sem) struct semaphore sem = MUTEX_LOCKED
#endif
Rebuild the kernel and the modules (if you configured to build as
modules), and install the new kernel and the new modules. Reboot the
system.
If you are using modules, you need to load the modules in a certain
order. Load usbcore.o first, followed by any drivers mouse.o,
keyboard.o, hub.o, etc, with the host controller (e.g. usb-uhci.o or
usb-ohci.o) added last.
Inspect the kernel logs. You should see lines like the following
(assuming use of UHCI and an external hub)
.......
Jul 19 20:46:02 rachel kernel: USB HID boot protocol mouse registered.
.......
Jul 19 20:46:02 rachel kernel: uhci_control_thread at c01b8c5c
Jul 19 20:46:02 rachel kernel: New bus registered
Jul 19 20:46:02 rachel kernel: USB hub driver registered
Jul 19 20:46:02 rachel kernel: uhci_connect_change: called for 0
.......
Jul 19 20:46:02 rachel kernel: USB hub found
Jul 19 20:46:02 rachel kernel: hub: 4-ports detected
Jul 19 20:46:02 rachel kernel: hub: individual port power switching
Jul 19 20:46:02 rachel kernel: hub: standalone hub
Jul 19 20:46:02 rachel kernel: hub: individual port over current protection
Jul 19 20:46:02 rachel kernel: hub: power on to power good time: 100ms
Jul 19 20:46:02 rachel kernel: hub: hub controller current requirement: 100mA
Jul 19 20:46:02 rachel kernel: hub: port 1 is removable
Jul 19 20:46:02 rachel kernel: hub: port 2 is removable
Jul 19 20:46:02 rachel kernel: hub: port 3 is removable
Jul 19 20:46:02 rachel kernel: hub: port 4 is removable
Jul 19 20:46:02 rachel kernel: hub: local power source is good
Jul 19 20:46:02 rachel kernel: hub: no over current condition exists
Jul 19 20:46:02 rachel kernel: enabling power on all ports
Jul 19 20:46:02 rachel kernel: uhci_connect_change: called for 1
.......
Jul 19 20:46:02 rachel kernel: hub: port 3 connection change
.......
OHCI and OHCI-HCD should give similar results. Don't worry about
failing transfers, this is a minor bug that shouldn't affect anything.
If there isn't anything that could be USB related (lines that mention
hubs, usb, ohci or uhci), likely causes are use of the wrong driver
(UHCI when you needed OHCI or OHCI when you needed UHCI), not
physically installing the hardware, a BIOS configuration that disables
USB or stuffing up the configuration or installation of the kernel.
_________________________________________________________________
Mouse Configuration
Firstly check that your mouse is being correctly sensed by the kernel.
If you type more /proc/interrupts , you should see a line that refers
to USB - typically ohci-usb or usb . If you click the mouse a few
times, and then have a look at /proc/interrupts the count associated
should increase (by two per click, one for down and one for up). This
count is a bit difficult to do with UHCI, since you have to subtract
the number of seconds that have elapsed between the checks of
/proc/interupts, and if you are using a USB keyboard, you need to
adjust for the key-presses as well.
Check /proc/misc. You should see something like
[bradh@rachel bradh]$ more /proc/misc
32 USB Mouse
1 psaux
You need to set up a /dev entry for the mouse. Use the following
command:
mknod /dev/usbmouse c 10 32
If you want to use the mouse under X, you need to:
* edit the XF86Config file (usually /usr/X11R6/lib/X11/XF86Config).
Add the following (anywhere sensible, ideally in the Input devices
area).
Section "Xinput"
SubSection "Mouse"
DeviceName "USB Mouse"
Protocol "IMPS/2"
Port "/dev/usbmouse"
AlwaysCore
EndSubSection
EndSection
* Restart the X server. If you don't have any mouse support at this
point, remember that Ctrl-Alt-1 will get you a virtual terminal
that you can use to kill the xserver and start debugging from the
error messages
If you want to use the mouse under gpm, run gpm -m /dev/usbmouse -t
ps2 (as superuser remember). You can make this the default if you edit
the initialisation files. These are typically named something like
rc.d and are in /etc/rc.d/ on RedHat distributions.
_________________________________________________________________
Keyboard Configuration
You may not need any operating system support at all to use a USB
keyboard if you have a PC architecture. There are several BIOSs
available where the BIOS can provide USB support from a keyboard
plugged into the root hub on the motherboard. This may or may not work
though other hubs and does not normally work with add-in boards, so
you might want to add in support anyway.
Check that your keyboard is being correctly sensed by the kernel. If
you type more /proc/interrupts , you should see a line that refers to
USB - typically ohci-usb or usb . If you type on the keyboard and then
have a look at /proc/interrupts the count should increase, although
you may need to subtract the number of seconds that have elapsed if
you are using UHCI.
At this point, you should be able to use your USB keyboard just as for
a normal keyboard. Be aware that LILO is not USB aware, and that
unless your BIOS supports a USB keyboard, you may not be able to
select a non-default boot image using the USB keyboard.
_________________________________________________________________
Hub Support
Hubs should work without other configuration. If the device works when
plugged into the root hub and not when plugged into an add-on hub,
make sure that you installed the hub module (if you built as modules).
Also check that you are not plugging a high powered device into a
bus-powered hub.
_________________________________________________________________
Printer Support
You need to set up a /dev entry for the printer. Use the following
command:
mknod /dev/usblp c 63 0
You should now be able to use this device in a normal /etc/printcap
entry. I recommend use of automated tools to generate such files, such
as RedHat's control panel print-tool.
If this does not appear to work, make sure that the major device
number for the printer has not changed (63 is an experimental range
number). Either check through the source code, or have a look in
/proc/devices. Also check that you have actually loaded the module,
and double-check the /etc/printcap entry - especially that the device
file matches the one you just created.
_________________________________________________________________
Abstract Control Model Support
You need to set up a /dev entry for the ACM device. Use the following
command:
mknod /dev/usbacm c 10 32
You should now be able to use a terminal emulator program to attach to
this /dev/usbacm and connect to your modem or other terminal device.
This is currently embrionic only.
Note that this is the same major device number and minor device number
as the USB mouse device driver. So you need to change the device
numbers for either the mouse or the ACM driver if you wish to use both
of these devices.
_________________________________________________________________
CPiA imager support
Support for CPiA cameras is included in the normal distribution, but
is not included in the normal Config.in in the linux/drivers/usb
directory. You need to add a line like
dep_tristate 'USB CPiA camera support' CONFIG_USB_CPIA $CONFIG_USB $CONFIG_VI
DEO_DEV
into this Config.in. Now reconfigure your kernel to support this
device and also enable Video For Linux support (under Character
Devices if using menuconfig).
You need to set up a /dev entry for the CPiA camera. Use the following
command:
mknod /dev/video0 c 81 0
ln -s /dev/video0 /dev/video
To use the device, you need some video tools. There are a fairly wide
range of tools available. [4]http://millenium.diads.com/bdirks has a
package that is a generally named something like apps19990527.tgz,
depending on the date of release. It has both X and text-mode tools.
Using the text mode tools will allow you to do things like
./vctrl 320x240x24
./vcat | rawtoppm -bgr 320 240 | xv -
These tools default to using /dev/video if not otherwise specified,
hence the symbolic link made previously.
At this stage, the CPiA camera can only do black and white images. If
you want to work on it, you should check the Vision CPiA website at
[5]http://home.eunet.no/~jtotland/vision
_________________________________________________________________
Mass Storage Devices
To be added.
_________________________________________________________________
USB /proc driver
To get /proc support for the USB system, you currently need to select
Preliminary /proc/bus/usb support. Then recompile and reinstall as
detailed above.
There are currently two interfaces to the /proc support for USB. They
are /proc/bus/usb/drivers and /proc/bus/usb/devices.
/proc/bus/usb/drivers just lists the currently registered drivers
(even if the driver is not being used by any device). This is most
useful when testing module installation, and checking for USB support
in an unknown kernel. Here is an example of its use:
[bradh@rachel bradh]$ more /proc/bus/usb/drivers
hub
printer
keyboard
mouse
/proc/bus/usb/devices lists information about the devices currently
attached to the USB bus. This is very useful when trying to figure out
if the device is correctly enumerated. Here is an example of its use,
showing the root hub, a hub, a keyboard, a mouse and a printer
adapter:
T: Lev=00 Prnt=00 Port=00 Cnt=00 Dev#= -1 Spd=12 If#= 0 MxCh= 2 Driver=(root
hub)
T: Lev=01 Prnt=00 Port=00 Cnt=01 Dev#= 1 Spd=12 If#= 0 MxCh= 4 Driver=hub
D: Ver= 1.00 Cls=09(hub ) Sub=00 Prot=00 MxPS= 8 #Cfgs= 1
P: Vendor=0451 ProdID=1446 Rev= 1.00
C:* #Ifs= 1 Cfg#= 1 Atr=e0 MxPwr=100mA
I: If#= 0 Alt= 0 #EPs= 1 Cls=09(hub ) Sub=00 Prot=00
E: Ad=81(I) Atr=03(Int.) MxPS= 1 Ivl=255ms
T: Lev=02 Prnt=01 Port=00 Cnt=01 Dev#= 2 Spd=12 If#= 0 MxCh= 0 Driver=print
er
D: Ver= 1.00 Cls=00(>ifc ) Sub=00 Prot=00 MxPS= 8 #Cfgs= 1
P: Vendor=0729 ProdID=1284 Rev= 1.04
C:* #Ifs= 1 Cfg#= 1 Atr=80 MxPwr= 98mA
I: If#= 0 Alt= 0 #EPs= 1 Cls=07(print) Sub=01 Prot=01
E: Ad=01(O) Atr=02(Bulk) MxPS= 64 Ivl= 0ms
I: If#= 0 Alt= 1 #EPs= 2 Cls=07(print) Sub=01 Prot=02
E: Ad=01(O) Atr=02(Bulk) MxPS= 64 Ivl= 0ms
E: Ad=82(I) Atr=02(Bulk) MxPS= 64 Ivl= 0ms
I: If#= 0 Alt= 2 #EPs= 3 Cls=ff(vend.) Sub=00 Prot=ff
E: Ad=01(O) Atr=02(Bulk) MxPS= 64 Ivl= 0ms
E: Ad=82(I) Atr=02(Bulk) MxPS= 64 Ivl= 0ms
E: Ad=83(I) Atr=03(Int.) MxPS= 4 Ivl= 1ms
T: Lev=02 Prnt=01 Port=01 Cnt=02 Dev#= 3 Spd=1.5 If#= 0 MxCh= 0 Driver=keybo
ard
D: Ver= 1.00 Cls=00(>ifc ) Sub=00 Prot=00 MxPS= 8 #Cfgs= 1
P: Vendor=045e ProdID=000b Rev= 0.82
C:* #Ifs= 1 Cfg#= 1 Atr=a0 MxPwr=100mA
I: If#= 0 Alt= 0 #EPs= 1 Cls=03(HID ) Sub=01 Prot=01
E: Ad=81(I) Atr=03(Int.) MxPS= 8 Ivl= 10ms
T: Lev=02 Prnt=01 Port=02 Cnt=03 Dev#= 4 Spd=1.5 If#= 0 MxCh= 0 Driver=mouse
D: Ver= 1.00 Cls=00(>ifc ) Sub=00 Prot=00 MxPS= 8 #Cfgs= 1
P: Vendor=046d ProdID=c001 Rev= 1.10
C:* #Ifs= 1 Cfg#= 1 Atr=a0 MxPwr= 50mA
I: If#= 0 Alt= 0 #EPs= 1 Cls=03(HID ) Sub=01 Prot=02
E: Ad=81(I) Atr=03(Int.) MxPS= 8 Ivl= 10ms
The information in the /proc/bus/usb/devices output is arranged in
groups:
* The line that starts with T: is the topology. Lev indicates the
level of the device, starting at level 00 for the root hub, level
01 for any device attached to the root hub, level 02 for devices
attached to hubs at level 01, and so on. Prnt is the parent device
for this device (always 00 for the root hub and any device
attached to the root hub). Port is the port on the parent device,
starting at 00 for the first port on each device. Prnt/Port is
unique per bus. Cnt indicates what number device this is, at this
level, based on the enumeration order within that level of the
topology, starting at 01 for the first device. Dev# indicates what
number device this is, irrespective of level, based on the bus
enumeration order. Spd indicates what speed this device is running
at, in Mbps (either 1.5 or 12 with the current version of USB).
If# indicates what number interface is currently selected. MxCh
indicates how many devices can be connected to this device, and is
00 for anything except a hub. Driver indicates which device driver
is being used for this device - an entry of (none) indicates that
no driver is being used.
* The line that starts with D: is information from the device
descriptor. Ver indicates which USB specification version the
device claims to meet. Cls indicates which device class the device
is claiming to meet, in both hexadecimal and as a string. A Cls
entry of 00(>ifc) indicates that the device class specification
compliance is interface dependent, and the interface descriptor
should be read for device class information. Sub indicates which
sub-class (within the Cls entry), the device meets. MxPS indicates
how big the packets from Endpoint 0 are. #Cfgs indicates how many
configurations this device has.
* Much like D:, the line that starts with P: is information from the
device descriptor, and is seperated mainly because it wouldn't all
fit on one line. Vendor indicates the Vendor Identification code
for the device, and ProdID indicates the Product Identification
code for the device. Rev indicates the product revision number.
* Refer to the USB specification clause 9.7.1 for further
information on device descriptors.
* The line that starts with C: is information from the configuration
descriptor - the number of C:lines per device is given by #Cfgs,
and the entry followed by an asterisk is the current
configuration. #If indicates how many interfaces the device has.
Cfg# indicates which configuration is being described. Atr is a
hexadecimal indication of the device attributes (0x80 for
bus-powered, 0x40 for self-powered, 0x20 for remote wake-up
capable). MPwr is the maximum power draw for this device
configuration, in milliamps. Refer to USB specification clause
9.7.2 for further information on configuration descriptors.
* The line that starts with I: is information from the interface
descriptor - the number of I: lines per C: line is given by the
#If entry. If# indicates which interface is being described within
a given device configuration. Alt indicates which alternate
setting of this interface is being described. #EP indicates how
many endpoints there are within the alternate setting for this
endpoint. Cls indicates which class the alternate setting of the
interface corresponds to, in both hexadecimal and as a character
string. Sub indicates which sub-class the alternate setting of the
interface belongs to. Prot indicates which interface protocol
(within a class and sub-class tuple) the alternate setting of the
interface conforms to. See USB specification clause 9.7.3 for
further information.
* The line that starts with E: is information from the interface
descriptor - the number of E: lines per I: line is given by the
#EP entry. Endpoint 0 is not displayed. Ad indicates the endpoint
address, with a letter to indicate whether the endpoint is an In
or Out endpoint. Atr indicate the attribute (transfer type)
associated with the endpoint, followed by a string translating the
transfer type. MxPS indicates the maximum packet size this
endpoint is capable of sending or receiving, as appropriate. For
isochronous transfers, MxPS indicates how much bandwidth needs to
be reserved. Ivl indicates the interval, in milliseconds, between
polling of interrupt endpoints. Ivl is ignored for bulk and
control transfers, and is set to 1 for isochronous transfers. See
USB specification clause 9.7.4 for further information on endpoint
descriptors.
Refer to linux/Documentation/proc_usb_format.txt for more information
on using the /proc/bus/usb information.
_________________________________________________________________
Frequently Asked Questions
There certain questions that keep reappearing. This section tries to
answer those questions.
_________________________________________________________________
How do I write a driver
You study the kernel source. You find a driver that is similar to what
you need to do, and you adapt it till it works. In this context,
similar is in terms of what transfers you need to do, not in what the
device looks like.
_________________________________________________________________
What is a good book on USB
I have only read one, and thought it was very poor. I suggest that you
get the specifications from [6]http://www.usb.org, which are at no
cost, are quite readable, and are up to date.
_________________________________________________________________
I have a vendor specific device, here is the descriptors
The descriptors are essential, but not sufficient, to write a driver.
You need the low level design detail from the vendor. In addition,
don't be surprised if the descriptor is not specification compliant -
all bets are off with vendor devices. Remember that descriptors are
just data bytes from the device, and reprogramming the device can make
any text appear, irrespective of what the device is really capable of.
_________________________________________________________________
What major and minor numbers should I use for my driver?
Use a major number in the experimental or demonstration ranges. There
is no official major number assigned for USB at this time. Use
whatever minor number you like.
_________________________________________________________________
How do I make USB work on my Sony Vaio laptop?
You need to turn off the BIOS option for Plug-n-Pray operating system
support. Then it should work fine.
_________________________________________________________________
Corrections
Please send comments on this document to the author, preferably by
E-Mail (<[7]brad.hards@dao.defence.gov.au>), including the version
number: ($Revision: 0.6 $).
References
1. mailto:linux-usb@suse.com
2. mailto:majordomo@suse.com
3. mailto:majordomo@suse.com
4. http://millenium.diads.com/bdirks
5. http://home.eunet.no/~jtotland/vision
6. http://www.usb.org/
7. mailto:brad.hards@dao.defence.gov.au
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