Re: [PATCH 0/8] serial: 8250: Add 485 emulation to 8250_dw.

[Giulio Benetti]

Hi everybody,

Il 04/06/2018 12:34, Matwey V. Kornilov ha scritto:
> 2018-06-04 13:12 GMT+03:00 Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>:
> > On Fri, 2018-06-01 at 14:40 +0200, Giulio Benetti wrote:
> > > Need to handle rs485 with 8250_dw port.
> > >
> > > Use existing em485 emulation layer for 8250 taking care to fix some
> > > bug
> > > and taking care especially of RTS_AFTER_SEND case.
> >
> > I don't see in Cc list author of rs485 code, who might be interested in
> > this.
> >
> > So, added him here.

Thanks Andy for adding in Cc an reviewing.
Dumb question: how did you find him?
I thought he was between people on get_maintainer.pl output.

> >
>
> Hi, Andy
>
> Nice to see you there. I will look through the code later.
> I always thought that DW has its own hardware rs485 support.

Hi Matwey,
I've checked on Synopsis Designware 8250 datasheet and it's not supported.
Here is datasheet I went through:
https://linux-sunxi.org/images/d/d2/Dw_apb_uart_db.pdf

On IER register there is not TEMT bit or something like that used in 
8250_omap.

Am I right?

Thanks everybody and
best regards

--
Giulio Benetti
CTO

MICRONOVA SRL
Sede: Via A. Niedda 3 - 35010 Vigonza (PD)
Tel. 049/8931563 - Fax 049/8931346
Cod.Fiscale - P.IVA 02663420285
Capitale Sociale â 26.000 i.v.
Iscritta al Reg. Imprese di Padova N. 02663420285
Numero R.E.A. 258642

> > > Giulio Benetti (8):
> > >    serial: 8250_dw: add em485 support
> > >    serial: 8250_dw: allow enable rs485 at boot time
> > >    serial: 8250: Copy em485 from port to real port.
> > >    serial: 8250: Handle case port doesn't have TEMT interrupt using
> > >      em485.
> > >    serial: 8250_dw: treat rpm suspend with -EBUSY if RS485 ON and
> > >      RTS_AFTER_SEND
> > >    serial: 8250: Copy mctrl when register port.
> > >    serial: 8250: Make em485_rts_after_send() set mctrl according to rts
> > >      state.
> > >    serial: core: Mask mctrl with TIOCM_RTS too if rs485 on and
> > >      RTS_AFTER_SEND set.
> > >
> > >   drivers/tty/serial/8250/8250.h      |  2 +-
> > >   drivers/tty/serial/8250/8250_core.c |  2 ++
> > >   drivers/tty/serial/8250/8250_dw.c   | 41
> > > ++++++++++++++++++++++++++++-
> > >   drivers/tty/serial/8250/8250_omap.c |  2 +-
> > >   drivers/tty/serial/8250/8250_port.c | 33 ++++++++++++++++-------
> > >   drivers/tty/serial/serial_core.c    | 12 ++++++++-
> > >   include/linux/serial_8250.h         |  1 +
> > >   7 files changed, 79 insertions(+), 14 deletions(-)
> >
> > --
> > Andy Shevchenko <andriy.shevchenko@xxxxxxxxxxxxxxx>
> > Intel Finland Oy