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Date:   Wed, 18 May 2022 13:59:30 +0200
From:   Greg KH <gregkh@linuxfoundation.org>
To:     Belisko Marek <marek.belisko@gmail.com>
Cc:     linux-serial@vger.kernel.org
Subject: Re: custom serial driver node not created
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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.

And why did you pick the ttyTX name?  That's already reserved for that
driver, you should use a new one, right?

And what hardware are you writing this driver for that we don't already
have a driver for it?

thanks,

greg k-h