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Message-Id: <1464948011-377-11-git-send-email-geert+renesas@glider.be>
Date: Fri, 3 Jun 2016 12:00:10 +0200
From: Geert Uytterhoeven <geert+renesas@...der.be>
To: Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
Jiri Slaby <jslaby@...e.com>,
Peter Hurley <peter@...leysoftware.com>
Cc: Magnus Damm <magnus.damm@...il.com>,
Laurent Pinchart <laurent.pinchart+renesas@...asonboard.com>,
Yoshinori Sato <ysato@...rs.sourceforge.jp>,
linux-serial@...r.kernel.org, linux-renesas-soc@...r.kernel.org,
linux-sh@...r.kernel.org, linux-kernel@...r.kernel.org,
Geert Uytterhoeven <geert+renesas@...der.be>
Subject: [PATCH v3 10/11] 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@...der.be>
---
v3:
- No changes,
v2:
- New.
---
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 b9d027af0f3e71f6..02b240a02dc6a593 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);
--
1.9.1
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