Re: Extending serial port linux driver to toggle RS485 direction pin (GPIO)

[Greg KH <gregkh@linuxfoundation.org>]

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On Wed, Nov 03, 2021 at 08:23:38AM +0100, Jochen Mades wrote:
> Hi Greg,
> 
> thanks for your fast reply. I checked the sources you mentioned below, that helps a bit..
> 
> Could you please give me some more background what you mean with your question:
> > You could do much the same in the pl011_rs485_tx_start() function when
> > SER_RS485_RX_DURING_TX and SER_RS485_RTS_ON_SEND are checked, right?
> 
> Is there already a concept for RS485 drivers?

Yes, RS485 drivers control lines like you are looking for in order to
properly handle the protocol requirements.

> ...or where to find "pl011_rs485_tx_start()"?

Look in the kernel source tree for that function, that's in the driver
you were looking to modify, right?

thanks,

greg k-h