On 03/26/2015 06:03 PM, Maxime Coquelin wrote:
>>> +static void stm32_set_termios(struct uart_port *port, struct ktermios *termios,
>>> + struct ktermios *old)
>>> +{
>>> + unsigned int baud;
>>> + u32 usardiv, mantissa, fraction;
>>> + tcflag_t cflag;
>>> + u32 cr1, cr2, cr3;
>>> + unsigned long flags;
>>> +
>>> + baud = uart_get_baud_rate(port, termios, old, 0, port->uartclk / 16);
>>> + cflag = termios->c_cflag;
>>> +
>>> + spin_lock_irqsave(&port->lock, flags);
>>> +
>>> + /* Stop serial port and reset value */
>>> + writel_relaxed(0, port->membase + USART_CR1);
>>> +
>>> + cr1 = USART_CR1_TE | USART_CR1_RE | USART_CR1_UE | USART_CR1_RXNEIE;
>>> +
>>> + if (cflag & CSTOPB)
>>> + cr2 = USART_CR2_STOP_2B;
>>> +
>>> + if (cflag & PARENB) {
>>> + cr1 |= USART_CR1_PCE;
>>> + if ((cflag & CSIZE) == CS8)
>>> + cr1 |= USART_CR1_M;
>>> + }
>>> +
>>> + if (cflag & PARODD)
>>> + cr1 |= USART_CR1_PS;
>>> +
>>> + if (cflag & CRTSCTS)
>>> + cr3 = USART_CR3_RTSE | USART_CR3_CTSE;
>>
>> If this means autoflow control, then you need to define
>> throttle()/unthrottle() methods, otherwise the serial core won't
>> be able to throttle the remote when input buffers are about
>> to overflow.
>>
>> And you should only enable the autoCTS and let the serial
>> core enable autoRTS through set_mctrl(TIOCM_RTS).
>>
>> Just let me know if you need more info about how to do this.
>
> Ok, let's see if I have well understood.
>
> USART_CR3_RTSE should be set/cleared in set_mctrl(), depending on
> TIOCM_RTS value.
> The throttle callback should disable the rx interrupt, and the
> unthrottle enable it.
> For CTS, it should be enabled in set_termios() if CRTSCTS, as done here.
>
> Am I right?
Yeah, basically. You also have to indicate to the serial core that you
require throttle/unthrottle handling in this mode by setting port->status.
Your set_termios() method would look like:
port->status &= ~(UPSTAT_AUTOCTS | UPSTAT_AUTORTS);
if (cflag & CRTSCTS) {
port->status |= UPSTAT_AUTOCTS | UPSTAT_AUTORTS;
cr3 = USART_CR3_CTSE;
}
and your set_mctrl() method would look like:
if ((mctrl & TIOCM_RTS) && (port->status & UPSTAT_AUTORTS))
stm32_set_bits(port, USART_CR3, USART_CR3_RTSE);
else
stm32_clear_bits(port, USART_CR3, USART_CR3_RTSE);
The UPSTAT_AUTOCTS doesn't really do anything right now but please
use it anyway to indicate this driver has that functionality.
Regards,
Peter Hurley
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