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Old 08-29-2004, 09:10 PM   #1
Registered: Aug 2004
Location: Oregon, USA
Distribution: Ubuntu 6.06; Debian Testing
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How does Linux decide what device in /dev to use for a piece of hardware?

I'm asking this because I want my TI Graph-Link USB to work with TiLP, which seems to expect the cable to be at /dev/tiusb0, but there isn't one by default. I can create a /dev/tiusb0 file, but I have no idea how to make it actually point at the cable and use the tiglusb driver. On bootup, it looks like th kernel finds the link cable and sets up tiglusb for it, but it doesn't make /dev/tiusb0.

drivers/usb/misc/tiglusb.c: firmware revision 1.03
usbcore: registered new driver tiglusb
drivers/usb/misc/tiglusb.c: TI-GRAPH LINK USB (aka SilverLink) driver, version 1.07
Old 08-30-2004, 12:20 AM   #2
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I don't really know the answer to this, except to say the /dev files are created by the mknod command, specifying major and minor device numbers, which I can only guess are hard-wired into the associated driver.

Since you are using Debian, why not just install the TILP package

which should take care of all that stuff automatically?
Old 08-30-2004, 09:25 AM   #3
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it's the driver which manages such things... This how it should happen for a classic driver (I think it may differ for certain 'cause of USB norm):
-You insert the driver which will probe your hardware (memory allocation for PCI, which IRQ to use, does IRQ is shared, cretion of device node...)
-Then the driver is ready When an interrupt arrives, the kernel "redirects" it according IRQ number (that's not completly exact, but that's simpler :P). The driver process the IRQ, ie will do a task according to what it was written in the registers...

And of course to read/write registers, Linux uses /dev/something... So if your device is correctly detected, there should have a /dev/something for it... maybe you use devfs filesystem (like me ) and so the file is /dev/usb/a/long/path/TILP0

Old 08-30-2004, 11:38 AM   #4
Registered: Aug 2004
Location: Oregon, USA
Distribution: Ubuntu 6.06; Debian Testing
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maroonbaboon: I did install the Debian Package, but TiLP is not functional.

Oliv': I think I'm using ext3 has a page that says this
You may need to create devices entries: do an 'mknod c 110 15 /dev/tiusb0'.
Think to set perms with: 'chmod 0660 /dev/tiusb0'.

To load the module, either use insmod or modprobe the usual way, or run "make load". To unload the module, use rmmod the usual way, or run "make unload".
So I think I'm on track with my needing to do something to make an entry in /dev/

This guy who wrote the mknod command must not have tested his command since the arguements are in the wrong order, so I'm thinking maybe he got the major and minor device numbers wrong?

Are the numbes on this page the major and minor numbers? If so, would major be 115 and minor be 16 instead of the 110 and 15 on the site?

And how is modprobe and insmod used "the usual way"?
Old 08-30-2004, 04:06 PM   #5
Registered: Aug 2004
Location: Oregon, USA
Distribution: Ubuntu 6.06; Debian Testing
Posts: 40

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I got TiLP working with the commands:

(as root)
mknod /dev/tiusb0 c 115 16
modprobe -r tiglusb
modprobe tiglusb
chmod 0660 /dev/tiusb0


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