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Date: Thu, 7 Oct 2010 22:08:52 +0100
From: Alan Cox <alan@lxorguk.ukuu.org.uk>
To: Daniel Walker <dwalker@codeaurora.org>
Cc: Mike Frysinger <vapier@gentoo.org>, linux-kernel@vger.kernel.org,
        "Hyok S. Choi" <hyok.choi@samsung.com>,
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        Jason Wessel <jason.wessel@windriver.com>,
        Philippe Langlais <philippe.langlais@stericsson.com>
Subject: Re: [PATCH] serial: DCC(JTAG) serial and console emulation support
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> > I would agree 100% with this for the driver in question. The tty_port
> > helpers now make it trivial to do so and it'll be small and clean as a
> > result.
> 
> Can you give some example of other drivers which have done this?

The blackfin driver is probably the nicest example for a very simple
device but see also the USB serial drivers (complex example), the SDIO
serial support (shows how to do fancy hotpluggable device stuff with it).

Basically tty_port_open/tty_port_close/tty_port_hangup do all the icky
nasty POSIX open/close/hangup handling and provide you with simple
methods to implement activate/shutdown of a port and carrier detect etc
most of which you don't even need to supply.

You can also skip a lot of other stuff like modem lines - although I can
see why you might want to provide an emulated modem line response for a
console emulation.

Alan