On Thu, 21 Jun 2012, Vishal Nandanwar wrote:
> Hi,
>
> I am trying to understand the USB device driver writing mechanism and
> architecture. I have gone through the LDD book as well.
>
> For learning purpose I am trying to write a driver for a pen drive
> i.e. USB mass storage.
That's a terrible way to learn. The mass-storage driver is one of the
most complicated ones in the USB subsystem. You should start with
something simpler.
> Linux do have the usb-storage driver which is
> used for pen drive. I have gone through the ../driver/usb/storage
> folder of Linux source code and found there are few drivers(karma,
> freecom) which uses usb-storage to achive there functionality.
Yes. Those sub-drivers are needed because their devices don't use the
standard USB mass-storage protocol.
> what is the mechanism to write a driver for pen drive(USB mass
> storage)? Is there any guide/help document which describes how to
> create a interface driver on top of usb-storage driver, so when my pen
> driver is connected it should use my driver?
I can tell you in one word how to write a driver for your pen drive:
Don't!
If you don't write a special driver then the pen drive should work
perfectly well. If you did try to write a special interface sub-driver
for it, you'd find that your driver had nothing to do because
usb-storage already handles everything.
Alan Stern
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