Adding GPIO/SPI/I2C functionality to FTDI driver

Greg KH greg at
Tue Sep 22 15:02:03 EDT 2015

On Tue, Sep 22, 2015 at 06:28:47PM +0200, chrysn wrote:
> Hello kernelnewbies list,
> I've run into situations where it would be practical to have the GPIO,
> I2C and SPI functionality some FTDI chips provide as kernel devices.
> (The chips are more often used as USB serial adapters; only that feature
> is supported by the current kernel drivers).
> The presence of an extensive userspace library (libftdi) and the
> observation of a project in a similar situation[1] that has not made it
> into the kernel makes me doubt that implementing that in the kernel is
> the way to go.
> I've written up more thoughts on this on [2], including exploration of
> userspace SPI/GPIO/I2C devices (think FUSE / USBIP / uinput), but it
> boils down to a simple question:
> Is support for alternative operation modes in FTDI chips something that
> is welcome and (easily) feasible in the kernel?

This comes up every other month or so on the linux-usb mailing list.
See the discussions there about how to do this properly in a way that
will be accepted by the USB maintainers if you wish to do this work.

And yes, this would be very welcome, but no one seems to be willing to
do the work :(


greg k-h

More information about the Kernelnewbies mailing list