Donate to e Foundation | Murena handsets with /e/OS | Own a part of Murena! Learn more

Commit 33f50ffc authored by Geert Uytterhoeven's avatar Geert Uytterhoeven Committed by Greg Kroah-Hartman
Browse files

serial: sh-sci: Fix support for hardware-assisted RTS/CTS 



The existing support for hardware-assisted RTS/CTS is rudimentary and
doesn't work.

Add support for hardware-assisted RTS/CTS hardware flow control for the
(H)SCIF, SCIFA, and SCIFB variants.

Signed-off-by: default avatarGeert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent e9d7a45a

drivers/tty/serial/sh-sci.c

+83 −7
Original line number Diff line number Diff line
@@ -141,6 +141,8 @@ struct sci_port { 
	struct timer_list		rx_timer;

	unsigned int			rx_timeout;

#endif



	bool autorts;

};



#define SCI_NPORTS CONFIG_SERIAL_SH_SCI_NR_UARTS
@@ -1811,6 +1813,46 @@ static unsigned int sci_tx_empty(struct uart_port *port) 
	return (status & SCxSR_TEND(port)) && !in_tx_fifo ? TIOCSER_TEMT : 0;

}



static void sci_set_rts(struct uart_port *port, bool state)

{

	if (port->type == PORT_SCIFA || port->type == PORT_SCIFB) {

		u16 data = serial_port_in(port, SCPDR);



		/* Active low */

		if (state)

			data &= ~SCPDR_RTSD;

		else

			data |= SCPDR_RTSD;

		serial_port_out(port, SCPDR, data);



		/* RTS# is output */

		serial_port_out(port, SCPCR,

				serial_port_in(port, SCPCR) | SCPCR_RTSC);

	} else if (sci_getreg(port, SCSPTR)->size) {

		u16 ctrl = serial_port_in(port, SCSPTR);



		/* Active low */

		if (state)

			ctrl &= ~SCSPTR_RTSDT;

		else

			ctrl |= SCSPTR_RTSDT;

		serial_port_out(port, SCSPTR, ctrl);

	}

}



static bool sci_get_cts(struct uart_port *port)

{

	if (port->type == PORT_SCIFA || port->type == PORT_SCIFB) {

		/* Active low */

		return !(serial_port_in(port, SCPDR) & SCPDR_CTSD);

	} else if (sci_getreg(port, SCSPTR)->size) {

		/* Active low */

		return !(serial_port_in(port, SCSPTR) & SCSPTR_CTSDT);

	}



	return true;

}



/*

 * Modem control is a bit of a mixed bag for SCI(F) ports. Generally

 * CTS/RTS is supported in hardware by at least one port and controlled
@@ -1841,6 +1883,31 @@ static void sci_set_mctrl(struct uart_port *port, unsigned int mctrl) 
	}



	mctrl_gpio_set(s->gpios, mctrl);



	if (!(s->cfg->capabilities & SCIx_HAVE_RTSCTS))

		return;



	if (!(mctrl & TIOCM_RTS)) {

		/* Disable Auto RTS */

		serial_port_out(port, SCFCR,

				serial_port_in(port, SCFCR) & ~SCFCR_MCE);



		/* Clear RTS */

		sci_set_rts(port, 0);

	} else if (s->autorts) {

		if (port->type == PORT_SCIFA || port->type == PORT_SCIFB) {

			/* Enable RTS# pin function */

			serial_port_out(port, SCPCR,

				serial_port_in(port, SCPCR) & ~SCPCR_RTSC);

		}



		/* Enable Auto RTS */

		serial_port_out(port, SCFCR,

				serial_port_in(port, SCFCR) | SCFCR_MCE);

	} else {

		/* Set RTS */

		sci_set_rts(port, 1);

	}

}



static unsigned int sci_get_mctrl(struct uart_port *port)
@@ -1853,10 +1920,14 @@ static unsigned int sci_get_mctrl(struct uart_port *port) 


	/*

	 * CTS/RTS is handled in hardware when supported, while nothing

	 * else is wired up. Keep it simple and simply assert CTS/DSR/CAR.

	 * else is wired up.

	 */

	if (IS_ERR_OR_NULL(mctrl_gpio_to_gpiod(gpios, UART_GPIO_CTS)))

	if (s->autorts) {

		if (sci_get_cts(port))

			mctrl |= TIOCM_CTS;

	} else if (IS_ERR_OR_NULL(mctrl_gpio_to_gpiod(gpios, UART_GPIO_CTS))) {

		mctrl |= TIOCM_CTS;

	}

	if (IS_ERR_OR_NULL(mctrl_gpio_to_gpiod(gpios, UART_GPIO_DSR)))

		mctrl |= TIOCM_DSR;

	if (IS_ERR_OR_NULL(mctrl_gpio_to_gpiod(gpios, UART_GPIO_DCD)))
@@ -1927,6 +1998,7 @@ static void sci_shutdown(struct uart_port *port) 


	dev_dbg(port->dev, "%s(%d)\n", __func__, port->line);



	s->autorts = false;

	mctrl_gpio_disable_ms(to_sci_port(port)->gpios);



	spin_lock_irqsave(&port->lock, flags);
@@ -2248,15 +2320,18 @@ static void sci_set_termios(struct uart_port *port, struct ktermios *termios, 


	sci_init_pins(port, termios->c_cflag);



	port->status &= ~UPSTAT_AUTOCTS;

	s->autorts = false;

	reg = sci_getreg(port, SCFCR);

	if (reg->size) {

		unsigned short ctrl = serial_port_in(port, SCFCR);



		if (s->cfg->capabilities & SCIx_HAVE_RTSCTS) {

			if (termios->c_cflag & CRTSCTS)

				ctrl |= SCFCR_MCE;

			else

				ctrl &= ~SCFCR_MCE;

		if ((port->flags & UPF_HARD_FLOW) &&

		    (termios->c_cflag & CRTSCTS)) {

			/* There is no CTS interrupt to restart the hardware */

			port->status |= UPSTAT_AUTOCTS;

			/* MCE is enabled when RTS is raised */

			s->autorts = true;

		}



		/*
@@ -2958,6 +3033,7 @@ static int sci_probe_single(struct platform_device *dev, 
			dev_err(&dev->dev, "Conflicting RTS/CTS config\n");

			return -EINVAL;

		}

		sciport->port.flags |= UPF_HARD_FLOW;

	}



	ret = uart_add_one_port(&sci_uart_driver, &sciport->port);