From: Yegor Yefremov <yegorslists@xxxxxxxxxxxxxx>
This patch permits the usage for GPIOs to control
the CTS/RTS/DTR/DSR/DCD/RI signals.
Signed-off-by: Yegor Yefremov <yegorslists@xxxxxxxxxxxxxx>
---
Changes:
v4: rework mctrl_gpio_init() return value handling
v2: - use newly introduced serial8250_in_MCR/serial8250_out_MCR
- don't use autoRTS/CTS, if RTS pin is made via GPIO
Documentation/devicetree/bindings/serial/8250.txt | 19 ++++++++++++
drivers/tty/serial/8250/8250.h | 35 ++++++++++++++++++++++-
drivers/tty/serial/8250/8250_core.c | 4 +++
drivers/tty/serial/8250/8250_omap.c | 31 +++++++++++---------
drivers/tty/serial/8250/8250_port.c | 7 ++++-
drivers/tty/serial/8250/Kconfig | 1 +
include/linux/serial_8250.h | 1 +
7 files changed, 83 insertions(+), 15 deletions(-)
diff --git a/Documentation/devicetree/bindings/serial/8250.txt b/Documentation/devicetree/bindings/serial/8250.txt
index 936ab5b..f5561ac 100644
--- a/Documentation/devicetree/bindings/serial/8250.txt
+++ b/Documentation/devicetree/bindings/serial/8250.txt
@@ -42,6 +42,9 @@ Optional properties:
- auto-flow-control: one way to enable automatic flow control support. The
driver is allowed to detect support for the capability even without this
property.
+- {rts,cts,dtr,dsr,rng,dcd}-gpios: specify a GPIO for RTS/CTS/DTR/DSR/RI/DCD
+ line respectively. It will use specified GPIO instead of the peripheral
+ function pin for the UART feature. If unsure, don't specify this property.
Note:
* fsl,ns16550:
@@ -63,3 +66,19 @@ Example:
interrupts = <10>;
reg-shift = <2>;
};
+
+Example for OMAP UART using GPIO-based modem control signals:
+
+ uart4: serial@49042000 {
+ compatible = "ti,omap3-uart";
+ reg = <0x49042000 0x400>;
+ interrupts = <80>;
+ ti,hwmods = "uart4";
+ clock-frequency = <48000000>;
+ cts-gpios = <&gpio3 5 GPIO_ACTIVE_LOW>;
+ rts-gpios = <&gpio3 6 GPIO_ACTIVE_LOW>;
+ dtr-gpios = <&gpio1 12 GPIO_ACTIVE_LOW>;
+ dsr-gpios = <&gpio1 13 GPIO_ACTIVE_LOW>;
+ dcd-gpios = <&gpio1 14 GPIO_ACTIVE_LOW>;
+ rng-gpios = <&gpio1 15 GPIO_ACTIVE_LOW>;
+ };
diff --git a/drivers/tty/serial/8250/8250.h b/drivers/tty/serial/8250/8250.h
index 533661c..5295deb 100644
--- a/drivers/tty/serial/8250/8250.h
+++ b/drivers/tty/serial/8250/8250.h
@@ -15,6 +15,8 @@
#include <linux/serial_reg.h>
#include <linux/dmaengine.h>
+#include "../serial_mctrl_gpio.h"
+
struct uart_8250_dma {
int (*tx_dma)(struct uart_8250_port *p);
int (*rx_dma)(struct uart_8250_port *p);
@@ -133,12 +135,43 @@ void serial8250_em485_destroy(struct uart_8250_port *p);
static inline void serial8250_out_MCR(struct uart_8250_port *up, int value)
{
+ int mctrl_gpio = 0;
+
serial_out(up, UART_MCR, value);
+
+ if (value & UART_MCR_RTS)
+ mctrl_gpio |= TIOCM_RTS;
+ if (value & UART_MCR_DTR)
+ mctrl_gpio |= TIOCM_DTR;
+
+ mctrl_gpio_set(up->gpios, mctrl_gpio);
}
static inline int serial8250_in_MCR(struct uart_8250_port *up)
{
- return serial_in(up, UART_MCR);
+ int mctrl, mctrl_gpio = 0;
+
+ mctrl = serial_in(up, UART_MCR);
+
+ /* save current MCR values */
+ if (mctrl & UART_MCR_RTS)
+ mctrl_gpio |= TIOCM_RTS;
+ if (mctrl & UART_MCR_DTR)
+ mctrl_gpio |= TIOCM_DTR;
+
+ mctrl_gpio = mctrl_gpio_get_outputs(up->gpios, &mctrl_gpio);
+
+ if (mctrl_gpio & TIOCM_RTS)
+ mctrl |= UART_MCR_RTS;
+ else
+ mctrl &= ~UART_MCR_RTS;
+
+ if (mctrl_gpio & TIOCM_DTR)
+ mctrl |= UART_MCR_DTR;
+ else
+ mctrl &= ~UART_MCR_DTR;
+
+ return mctrl;
}
#if defined(__alpha__) && !defined(CONFIG_PCI)
diff --git a/drivers/tty/serial/8250/8250_core.c b/drivers/tty/serial/8250/8250_core.c
index 0fbd7c0..c87cad0 100644
--- a/drivers/tty/serial/8250/8250_core.c
+++ b/drivers/tty/serial/8250/8250_core.c
@@ -1011,6 +1011,10 @@ int serial8250_register_8250_port(struct uart_8250_port *up)
if (up->port.flags & UPF_FIXED_TYPE)
uart->port.type = up->port.type;
+ uart->gpios = mctrl_gpio_init(&uart->port, 0);
+ if (uart->gpios == NULL && IS_ENABLED(CONFIG_GPIOLIB))
+ dev_err(uart->port.dev, "Failed to init mctrl_gpio\n");
+
serial8250_set_defaults(uart);
/* Possibly override default I/O functions. */
diff --git a/drivers/tty/serial/8250/8250_omap.c b/drivers/tty/serial/8250/8250_omap.c
index 61ad6c3..e14982f 100644
--- a/drivers/tty/serial/8250/8250_omap.c
+++ b/drivers/tty/serial/8250/8250_omap.c
@@ -134,18 +134,21 @@ static void omap8250_set_mctrl(struct uart_port *port, unsigned int mctrl)
serial8250_do_set_mctrl(port, mctrl);
- /*
- * Turn off autoRTS if RTS is lowered and restore autoRTS setting
- * if RTS is raised
- */
- lcr = serial_in(up, UART_LCR);
- serial_out(up, UART_LCR, UART_LCR_CONF_MODE_B);
- if ((mctrl & TIOCM_RTS) && (port->status & UPSTAT_AUTORTS))
- priv->efr |= UART_EFR_RTS;
- else
- priv->efr &= ~UART_EFR_RTS;
- serial_out(up, UART_EFR, priv->efr);
- serial_out(up, UART_LCR, lcr);
+ if (IS_ERR_OR_NULL(mctrl_gpio_to_gpiod(up->gpios,
+ UART_GPIO_RTS))) {
+ /*
+ * Turn off autoRTS if RTS is lowered and restore autoRTS
+ * setting if RTS is raised
+ */
+ lcr = serial_in(up, UART_LCR);
+ serial_out(up, UART_LCR, UART_LCR_CONF_MODE_B);
+ if ((mctrl & TIOCM_RTS) && (port->status & UPSTAT_AUTORTS))
+ priv->efr |= UART_EFR_RTS;
+ else
+ priv->efr &= ~UART_EFR_RTS;
+ serial_out(up, UART_EFR, priv->efr);
+ serial_out(up, UART_LCR, lcr);
+ }
}
/*
@@ -446,7 +449,9 @@ static void omap_8250_set_termios(struct uart_port *port,
priv->efr = 0;
up->port.status &= ~(UPSTAT_AUTOCTS | UPSTAT_AUTORTS | UPSTAT_AUTOXOFF);
- if (termios->c_cflag & CRTSCTS && up->port.flags & UPF_HARD_FLOW) {
+ if (termios->c_cflag & CRTSCTS && up->port.flags & UPF_HARD_FLOW
+ && IS_ERR_OR_NULL(mctrl_gpio_to_gpiod(up->gpios,
+ UART_GPIO_RTS))) {
/* Enable AUTOCTS (autoRTS is enabled when RTS is raised) */
up->port.status |= UPSTAT_AUTOCTS | UPSTAT_AUTORTS;
priv->efr |= UART_EFR_CTS;
diff --git a/drivers/tty/serial/8250/8250_port.c b/drivers/tty/serial/8250/8250_port.c
index d2b1825..7879b14 100644
--- a/drivers/tty/serial/8250/8250_port.c
+++ b/drivers/tty/serial/8250/8250_port.c
@@ -1618,6 +1618,8 @@ static void serial8250_disable_ms(struct uart_port *port)
if (up->bugs & UART_BUG_NOMSR)
return;
+ mctrl_gpio_disable_ms(up->gpios);
+
up->ier &= ~UART_IER_MSI;
serial_port_out(port, UART_IER, up->ier);
}
@@ -1630,6 +1632,8 @@ static void serial8250_enable_ms(struct uart_port *port)
if (up->bugs & UART_BUG_NOMSR)
return;
+ mctrl_gpio_enable_ms(up->gpios);
+
up->ier |= UART_IER_MSI;
serial8250_rpm_get(up);
@@ -1914,7 +1918,8 @@ unsigned int serial8250_do_get_mctrl(struct uart_port *port)
ret |= TIOCM_DSR;
if (status & UART_MSR_CTS)
ret |= TIOCM_CTS;
- return ret;
+
+ return mctrl_gpio_get(up->gpios, &ret);
}
EXPORT_SYMBOL_GPL(serial8250_do_get_mctrl);
diff --git a/drivers/tty/serial/8250/Kconfig b/drivers/tty/serial/8250/Kconfig
index e46761d..7f97e37 100644
--- a/drivers/tty/serial/8250/Kconfig
+++ b/drivers/tty/serial/8250/Kconfig
@@ -6,6 +6,7 @@
config SERIAL_8250
tristate "8250/16550 and compatible serial support"
select SERIAL_CORE
+ select SERIAL_MCTRL_GPIO if GPIOLIB
---help---
This selects whether you want to include the driver for the standard
serial ports. The standard answer is Y. People who might say N
diff --git a/include/linux/serial_8250.h b/include/linux/serial_8250.h
index 48ec765..923266c 100644
--- a/include/linux/serial_8250.h
+++ b/include/linux/serial_8250.h
@@ -111,6 +111,7 @@ struct uart_8250_port {
* if no_console_suspend
*/
unsigned char probe;
+ struct mctrl_gpios *gpios;
#define UART_PROBE_RSA (1 << 0)
/*
--
2.1.4
--
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