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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: Geert Uytterhoeven <geert+renesas@glider.be>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
This commit is contained in:
Geert Uytterhoeven 2016-06-03 12:00:10 +02:00 committed by Greg Kroah-Hartman
parent e9d7a45a03
commit 33f50ffc25
1 changed files with 83 additions and 7 deletions
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90
drivers/tty/serial/sh-sci.c
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@ -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);