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Date: Wed, 6 Jun 2018 21:16:37 +0200
From: Giulio Benetti <giulio.benetti@...ronovasrl.com>
To: Andy Shevchenko <andy.shevchenko@...il.com>
Cc: "Matwey V. Kornilov" <matwey.kornilov@...il.com>,
Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
Jiri Slaby <jslaby@...e.com>, Ed Blake <ed.blake@...drel.com>,
Joshua Scott <joshua.scott@...iedtelesis.co.nz>,
"open list:SERIAL DRIVERS" <linux-serial@...r.kernel.org>,
open list <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 1/4] serial: 8250_dw: add em485 support
Il 06/06/2018 18:51, Andy Shevchenko ha scritto:
> On Wed, Jun 6, 2018 at 12:51 PM, Giulio Benetti
> <giulio.benetti@...ronovasrl.com> wrote:
>> Need to use rs485 transceiver so let's use existing em485 485 emulation
>> layer on top of 8250.
>>
>> Add rs485_config callback to port.
>
> Besides the fact the series lacks of cover letter, I think it should
Sorry for that, next patchsets will have cover-letters.
> be postponed until we get a clear understanding how RS485 is supposed
> to be initialized and what exact problems you are trying to address.
>
>>
>> Signed-off-by: Giulio Benetti <giulio.benetti@...ronovasrl.com>
>> ---
>> drivers/tty/serial/8250/8250_dw.c | 31 +++++++++++++++++++++++++++++++
>> 1 file changed, 31 insertions(+)
>>
>> diff --git a/drivers/tty/serial/8250/8250_dw.c b/drivers/tty/serial/8250/8250_dw.c
>> index 6fcdb90f616a..45366e6e5411 100644
>> --- a/drivers/tty/serial/8250/8250_dw.c
>> +++ b/drivers/tty/serial/8250/8250_dw.c
>> @@ -314,6 +314,36 @@ static void dw8250_set_ldisc(struct uart_port *p, struct ktermios *termios)
>> serial8250_do_set_ldisc(p, termios);
>> }
>>
>> +static int dw8250_rs485_config(struct uart_port *p,
>> + struct serial_rs485 *rs485)
>> +{
>> + struct uart_8250_port *up = up_to_u8250p(p);
>> +
>> + /* Clamp the delays to [0, 100ms] */
>> + rs485->delay_rts_before_send = min(rs485->delay_rts_before_send, 100U);
>> + rs485->delay_rts_after_send = min(rs485->delay_rts_after_send, 100U);
>> +
>> + p->rs485 = *rs485;
>> +
>> + /*
>> + * Both serial8250_em485_init and serial8250_em485_destroy
>> + * are idempotent
>> + */
>> + if (rs485->flags & SER_RS485_ENABLED) {
>> + int ret = serial8250_em485_init(up);
>> +
>> + if (ret) {
>> + rs485->flags &= ~SER_RS485_ENABLED;
>> + p->rs485.flags &= ~SER_RS485_ENABLED;
>> + }
>> + return ret;
>> + }
>> +
>> + serial8250_em485_destroy(up);
>> +
>> + return 0;
>> +}
>> +
>> /*
>> * dw8250_fallback_dma_filter will prevent the UART from getting just any free
>> * channel on platforms that have DMA engines, but don't have any channels
>> @@ -449,6 +479,7 @@ static int dw8250_probe(struct platform_device *pdev)
>> p->serial_out = dw8250_serial_out;
>> p->set_ldisc = dw8250_set_ldisc;
>> p->set_termios = dw8250_set_termios;
>> + p->rs485_config = dw8250_rs485_config;
>>
>> p->membase = devm_ioremap(dev, regs->start, resource_size(regs));
>> if (!p->membase)
>> --
>> 2.17.1
>>
>
>
>
--
Giulio Benetti
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