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    SubjectRe: Writing a console/tty driver -- how to use tty_port?
    On Friday 29 October 2010, Alan Cox wrote:
    > On Thu, 28 Oct 2010 22:57:33 +0200
    > Arnd Bergmann <> wrote:
    > > On Wednesday 27 October 2010 23:04:13 Timur Tabi wrote:
    > > > Do you have an updated version of Tiny TTY that uses tty_port structures? I'm
    > > > trying to write a new TTY driver for a device that is not a UART, and I'm having
    > > > a hard time finding a good example. I suspect I need to understand the tty_port
    > > > structure, but I can't find any documentation for it.
    > >
    > > If the device is not a UART, the best option may be to make the driver
    > > a backend to the hvc driver, like e.g. drivers/char/hvc_tile.c.
    > >
    > > This works for all devices with or without interrupts that don't need
    > > to set up the communication parameters but simply provide a read/write
    > > character interface.
    > I really don't understand the love of hvc when the hvc drivers seem to be
    > bigger than native tty_port code and haul a whole blob of extra midlayer
    > glue into the system.

    Two reasons for me:

    * It does all the timers for the tty device to poll reads and retry writes.
    If someone writes similar code from scratch, they most likely get it wrong.

    * It's about the simplest interface you can imagine for a new backend driver,
    only register a data structure with two function pointers!


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