Re: custom serial driver node not created

[Greg KH <gregkh@linuxfoundation.org>]

On Wed, May 18, 2022 at 02:24:43PM +0200, Belisko Marek wrote:
> On Wed, May 18, 2022 at 1:59 PM Greg KH <gregkh@linuxfoundation.org> wrote:
> >
> > On Wed, May 18, 2022 at 01:41:18PM +0200, Belisko Marek wrote:
> > > Hello,
> > >
> > > I'm writing serial tty driver (it's SPI/UART converter) and I get
> > > inspired by this driver:
> > > https://github.com/raspberrypi/linux/blob/rpi-5.15.y/drivers/tty/serial/sc16is7xx.c
> > >
> > > I have driver probed and also added port to driver which I see in console:
> > > [ 2616.826105] spi0.0: ttyTX0 at I/O 0x1 (irq = 0, base_baud = 9375)
> > > is a test_driver
> > >
> > > so I should see it in /dev/ttyTX0 but it seems node is not created.
> > > Udev is running on a platform.
> > > Any ideas what can cause this?
> >
> > Without seeing the code itself, it's almost impossible to guess.
> >
> > Also note that udev does not create device nodes (hasn't for over a
> > decade).  devtmpfs in the kernel does that, udev just helps with
> > managing the permissions of created nodes if needed.
> OK thanks for clarification.
> >
> > And why did you pick the ttyTX name?  That's already reserved for that
> > driver, you should use a new one, right?
> I've should used also others like ttyTEST but result was same.
> >
> > And what hardware are you writing this driver for that we don't already
> > have a driver for it?
> I'm writing a driver for the following model: Linux CPU is connected
> with SPI with another CPU (Cortex M3) and this other CPU performs UART
> handling based on data which comes over SPI. I would like to expose
> Cortex M3 UARTS on linux as tty ports so it will act as standar serial
> device.
> 
> Code can be found here: https://pastebin.com/6qpUw2Jt

Are you sure that your test_probe() call is really being called?