From 33f50ffc253854cf6cd556786ae893c7454a1a67 Mon Sep 17 00:00:00 2001 From: Geert Uytterhoeven Date: Fri, 3 Jun 2016 12:00:10 +0200 Subject: [PATCH] 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 Signed-off-by: Greg Kroah-Hartman --- drivers/tty/serial/sh-sci.c | 90 ++++++++++++++++++++++++++++++++++--- 1 file changed, 83 insertions(+), 7 deletions(-) diff --git a/drivers/tty/serial/sh-sci.c b/drivers/tty/serial/sh-sci.c index b9d027af0f3e..02b240a02dc6 100644 --- a/drivers/tty/serial/sh-sci.c +++ b/drivers/tty/serial/sh-sci.c @@ -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 @@ done: 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); -- 2.20.1