tty/serial: Add helpers to use GPIOs to control modem lines and implement atmel_serial.c

This patch add some helpers to control modem lines (CTS/RTS/DSR...) via GPIO.
This will be useful for many boards which have a serial controller that only handle CTS/RTS pins (or even just RX/TX).

Signed-off-by Richard Genoud <[email protected]>

Acked-by Greg Kroah-Hartman <[email protected]>

---
 Documentation/serial/driver            |   25 ++++++
 drivers/tty/serial/Kconfig             |    3 +
 drivers/tty/serial/Makefile            |    3 +
 drivers/tty/serial/serial_mctrl_gpio.c |  143 ++++++++++++++++++++++++++++++++
 drivers/tty/serial/serial_mctrl_gpio.h |  110 ++++++++++++++++++++++++
 5 files changed, 284 insertions(+)
 create mode 100644 drivers/tty/serial/serial_mctrl_gpio.c
 create mode 100644 drivers/tty/serial/serial_mctrl_gpio.h

Documentation/serial/driver +25 -0

index c3a7689..3bba1ae 100644
@@ -429,3 +429,28 @@ thus:
 		struct uart_port	port;
 		int			my_stuff;
 	};
+
+Modem control lines via GPIO
+----------------------------
+
+Some helpers are provided in order to set/get modem control lines via GPIO.
+
+mctrl_gpio_init(dev, idx):
+	This will get the {cts,rts,...}-gpios from device tree if they are
+	present and request them, set direction etc, and return an
+	allocated structure. devm_* functions are used, so there's no need
+	to call mctrl_gpio_free().
+
+mctrl_gpio_free(dev, gpios):
+	This will free the requested gpios in mctrl_gpio_init().
+	As devm_* function are used, there's generally no need to call
+	this function.
+
+mctrl_gpio_to_gpiod(gpios, gidx)
+	This returns the gpio structure associated to the modem line index.
+
+mctrl_gpio_set(gpios, mctrl):
+	This will sets the gpios according to the mctrl state.
+
+mctrl_gpio_get(gpios, mctrl):
+	This will update mctrl with the gpios values.

drivers/tty/serial/Kconfig +3 -0

index 5d9b01a..95afd31 100644
@@ -1510,4 +1510,7 @@ config SERIAL_ST_ASC_CONSOLE
 
 endmenu
 
+config SERIAL_MCTRL_GPIO
+	tristate
+
 endif # TTY

drivers/tty/serial/Makefile +3 -0

index 3680854..bcf31da 100644
@@ -87,3 +87,6 @@ obj-$(CONFIG_SERIAL_EFM32_UART) += efm32-uart.o
 obj-$(CONFIG_SERIAL_ARC)	+= arc_uart.o
 obj-$(CONFIG_SERIAL_RP2)	+= rp2.o
 obj-$(CONFIG_SERIAL_FSL_LPUART)	+= fsl_lpuart.o
+
+# GPIOLIB helpers for modem control lines
+obj-$(CONFIG_SERIAL_MCTRL_GPIO) += serial_mctrl_gpio.o

drivers/tty/serial/serial_mctrl_gpio.c new file +143 -0

new file mode 100644
index 0000000..bf9560f
@@ -0,0 +1,143 @@
+/*
+ * Helpers for controlling modem lines via GPIO
+ *
+ * Copyright (C) 2014 Paratronic S.A.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ */
+
+#include <linux/err.h>
+#include <linux/device.h>
+#include <linux/gpio/consumer.h>
+#include <uapi/asm-generic/termios.h>
+
+#include "serial_mctrl_gpio.h"
+
+struct mctrl_gpios {
+	struct gpio_desc *gpio[UART_GPIO_MAX];
+};
+
+static const struct {
+	const char *name;
+	unsigned int mctrl;
+	bool dir_out;
+} mctrl_gpios_desc[UART_GPIO_MAX] = {
+	{ "cts", TIOCM_CTS, false, },
+	{ "dsr", TIOCM_DSR, false, },
+	{ "dcd", TIOCM_CD, false, },
+	{ "rng", TIOCM_RNG, false, },
+	{ "rts", TIOCM_RTS, true, },
+	{ "dtr", TIOCM_DTR, true, },
+	{ "out1", TIOCM_OUT1, true, },
+	{ "out2", TIOCM_OUT2, true, },
+};
+
+void mctrl_gpio_set(struct mctrl_gpios *gpios, unsigned int mctrl)
+{
+	enum mctrl_gpio_idx i;
+
+	if (IS_ERR_OR_NULL(gpios))
+		return;
+
+	for (i = 0; i < UART_GPIO_MAX; i++)
+		if (!IS_ERR_OR_NULL(gpios->gpio[i]) &&
+		    mctrl_gpios_desc[i].dir_out)
+			gpiod_set_value(gpios->gpio[i],
+					!!(mctrl & mctrl_gpios_desc[i].mctrl));
+}
+EXPORT_SYMBOL_GPL(mctrl_gpio_set);
+
+struct gpio_desc *mctrl_gpio_to_gpiod(struct mctrl_gpios *gpios,
+				      enum mctrl_gpio_idx gidx)
+{
+	if (!IS_ERR_OR_NULL(gpios) && !IS_ERR_OR_NULL(gpios->gpio[gidx]))
+		return gpios->gpio[gidx];
+	else
+		return NULL;
+}
+EXPORT_SYMBOL_GPL(mctrl_gpio_to_gpiod);
+
+unsigned int mctrl_gpio_get(struct mctrl_gpios *gpios, unsigned int *mctrl)
+{
+	enum mctrl_gpio_idx i;
+
+	/*
+	 * return it unchanged if the structure is not allocated
+	 */
+	if (IS_ERR_OR_NULL(gpios))
+		return *mctrl;
+
+	for (i = 0; i < UART_GPIO_MAX; i++) {
+		if (!IS_ERR_OR_NULL(gpios->gpio[i]) &&
+		    !mctrl_gpios_desc[i].dir_out) {
+			if (gpiod_get_value(gpios->gpio[i]))
+				*mctrl |= mctrl_gpios_desc[i].mctrl;
+			else
+				*mctrl &= ~mctrl_gpios_desc[i].mctrl;
+		}
+	}
+
+	return *mctrl;
+}
+EXPORT_SYMBOL_GPL(mctrl_gpio_get);
+
+struct mctrl_gpios *mctrl_gpio_init(struct device *dev, unsigned int idx)
+{
+	struct mctrl_gpios *gpios;
+	enum mctrl_gpio_idx i;
+	int err;
+
+	gpios = devm_kzalloc(dev, sizeof(*gpios), GFP_KERNEL);
+	if (!gpios)
+		return ERR_PTR(-ENOMEM);
+
+	for (i = 0; i < UART_GPIO_MAX; i++) {
+		gpios->gpio[i] = devm_gpiod_get_index(dev,
+						      mctrl_gpios_desc[i].name,
+						      idx);
+
+		/*
+		 * The GPIOs are maybe not all filled,
+		 * this is not an error.
+		 */
+		if (IS_ERR_OR_NULL(gpios->gpio[i]))
+			continue;
+
+		if (mctrl_gpios_desc[i].dir_out)
+			err = gpiod_direction_output(gpios->gpio[i], 0);
+		else
+			err = gpiod_direction_input(gpios->gpio[i]);
+		if (err) {
+			dev_dbg(dev, "Unable to set direction for %s GPIO",
+				mctrl_gpios_desc[i].name);
+			devm_gpiod_put(dev, gpios->gpio[i]);
+			gpios->gpio[i] = NULL;
+		}
+	}
+
+	return gpios;
+}
+EXPORT_SYMBOL_GPL(mctrl_gpio_init);
+
+void mctrl_gpio_free(struct device *dev, struct mctrl_gpios *gpios)
+{
+	enum mctrl_gpio_idx i;
+
+	if (IS_ERR_OR_NULL(gpios))
+		return;
+
+	for (i = 0; i < UART_GPIO_MAX; i++)
+		if (!IS_ERR_OR_NULL(gpios->gpio[i]))
+			devm_gpiod_put(dev, gpios->gpio[i]);
+	devm_kfree(dev, gpios);
+}
+EXPORT_SYMBOL_GPL(mctrl_gpio_free);

drivers/tty/serial/serial_mctrl_gpio.h new file +110 -0

new file mode 100644
index 0000000..400ba04
@@ -0,0 +1,110 @@
+/*
+ * Helpers for controlling modem lines via GPIO
+ *
+ * Copyright (C) 2014 Paratronic S.A.
+ *
+ * This program is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ */
+
+#ifndef __SERIAL_MCTRL_GPIO__
+#define __SERIAL_MCTRL_GPIO__
+
+#include <linux/err.h>
+#include <linux/device.h>
+#include <linux/gpio/consumer.h>
+
+enum mctrl_gpio_idx {
+	UART_GPIO_CTS,
+	UART_GPIO_DSR,
+	UART_GPIO_DCD,
+	UART_GPIO_RNG,
+	UART_GPIO_RI = UART_GPIO_RNG,
+	UART_GPIO_RTS,
+	UART_GPIO_DTR,
+	UART_GPIO_OUT1,
+	UART_GPIO_OUT2,
+	UART_GPIO_MAX,
+};
+
+/*
+ * Opaque descriptor for modem lines controlled by GPIOs
+ */
+struct mctrl_gpios;
+
+#ifdef CONFIG_GPIOLIB
+
+/*
+ * Set state of the modem control output lines via GPIOs.
+ */
+void mctrl_gpio_set(struct mctrl_gpios *gpios, unsigned int mctrl);
+
+/*
+ * Get state of the modem control output lines from GPIOs.
+ * The mctrl flags are updated and returned.
+ */
+unsigned int mctrl_gpio_get(struct mctrl_gpios *gpios, unsigned int *mctrl);
+
+/*
+ * Returns the associated struct gpio_desc to the modem line gidx
+ */
+struct gpio_desc *mctrl_gpio_to_gpiod(struct mctrl_gpios *gpios,
+				      enum mctrl_gpio_idx gidx);
+
+/*
+ * Request and set direction of modem control lines GPIOs.
+ * devm_* functions are used, so there's no need to call mctrl_gpio_free().
+ * Returns a pointer to the allocated mctrl structure if ok, -ENOMEM on
+ * allocation error.
+ */
+struct mctrl_gpios *mctrl_gpio_init(struct device *dev, unsigned int idx);
+
+/*
+ * Free the mctrl_gpios structure.
+ * Normally, this function will not be called, as the GPIOs will
+ * be disposed of by the resource management code.
+ */
+void mctrl_gpio_free(struct device *dev, struct mctrl_gpios *gpios);
+
+#else /* GPIOLIB */
+
+static inline
+void mctrl_gpio_set(struct mctrl_gpios *gpios, unsigned int mctrl)
+{
+}
+
+static inline
+unsigned int mctrl_gpio_get(struct mctrl_gpios *gpios, unsigned int *mctrl)
+{
+	return *mctrl;
+}
+
+static inline
+struct gpio_desc *mctrl_gpio_to_gpiod(struct mctrl_gpios *gpios,
+				      enum mctrl_gpio_idx gidx)
+{
+	return ERR_PTR(-ENOSYS);
+}
+
+static inline
+struct mctrl_gpios *mctrl_gpio_init(struct device *dev, unsigned int idx)
+{
+	return ERR_PTR(-ENOSYS);
+}
+
+static inline
+void mctrl_gpio_free(struct device *dev, struct mctrl_gpios *gpios)
+{
+}
+
+#endif /* GPIOLIB */
+
+#endif

This patch add some helpers to control modem lines (CTS/RTS/DSR...) via GPIO.
This will be useful for many boards which have a serial controller that only handle CTS/RTS pins (or even just RX/TX).

Signed-off-by Richard Genoud <[email protected]>

Tested-by Yegor Yefremov <[email protected]>

---
 Documentation/serial/driver            |   25 ++++++
 drivers/tty/serial/Kconfig             |    3 +
 drivers/tty/serial/Makefile            |    3 +
 drivers/tty/serial/serial_mctrl_gpio.c |  143 ++++++++++++++++++++++++++++++++
 drivers/tty/serial/serial_mctrl_gpio.h |  110 ++++++++++++++++++++++++
 5 files changed, 284 insertions(+)
 create mode 100644 drivers/tty/serial/serial_mctrl_gpio.c
 create mode 100644 drivers/tty/serial/serial_mctrl_gpio.h

Documentation/serial/driver +25 -0

index c3a7689..3bba1ae 100644
@@ -429,3 +429,28 @@ thus:
 		struct uart_port	port;
 		int			my_stuff;
 	};
+
+Modem control lines via GPIO
+----------------------------
+
+Some helpers are provided in order to set/get modem control lines via GPIO.
+
+mctrl_gpio_init(dev, idx):
+	This will get the {cts,rts,...}-gpios from device tree if they are
+	present and request them, set direction etc, and return an
+	allocated structure. devm_* functions are used, so there's no need
+	to call mctrl_gpio_free().
+
+mctrl_gpio_free(dev, gpios):
+	This will free the requested gpios in mctrl_gpio_init().
+	As devm_* function are used, there's generally no need to call
+	this function.
+
+mctrl_gpio_to_gpiod(gpios, gidx)
+	This returns the gpio structure associated to the modem line index.
+
+mctrl_gpio_set(gpios, mctrl):
+	This will sets the gpios according to the mctrl state.
+
+mctrl_gpio_get(gpios, mctrl):
+	This will update mctrl with the gpios values.

drivers/tty/serial/Kconfig +0 -0

index 5d9b01a..95afd31 100644

Quoted 56 lines · Richard Genoud

This patch add some helpers to control modem lines (CTS/RTS/DSR...) via GPIO.
This will be useful for many boards which have a serial controller that only handle CTS/RTS pins (or even just RX/TX).

Signed-off-by Richard Genoud <[email protected]>

Tested-by Yegor Yefremov <[email protected]>

---
 Documentation/serial/driver            |   25 ++++++
 drivers/tty/serial/Kconfig             |    3 +
 drivers/tty/serial/Makefile            |    3 +
 drivers/tty/serial/serial_mctrl_gpio.c |  143 ++++++++++++++++++++++++++++++++
 drivers/tty/serial/serial_mctrl_gpio.h |  110 ++++++++++++++++++++++++
 5 files changed, 284 insertions(+)
 create mode 100644 drivers/tty/serial/serial_mctrl_gpio.c
 create mode 100644 drivers/tty/serial/serial_mctrl_gpio.h

Documentation/serial/driver +25 -0

index c3a7689..3bba1ae 100644
@@ -429,3 +429,28 @@ thus:
 		struct uart_port	port;
 		int			my_stuff;
 	};
+
+Modem control lines via GPIO
+----------------------------
+
+Some helpers are provided in order to set/get modem control lines via GPIO.
+
+mctrl_gpio_init(dev, idx):
+	This will get the {cts,rts,...}-gpios from device tree if they are
+	present and request them, set direction etc, and return an
+	allocated structure. devm_* functions are used, so there's no need
+	to call mctrl_gpio_free().
+
+mctrl_gpio_free(dev, gpios):
+	This will free the requested gpios in mctrl_gpio_init().
+	As devm_* function are used, there's generally no need to call
+	this function.
+
+mctrl_gpio_to_gpiod(gpios, gidx)
+	This returns the gpio structure associated to the modem line index.
+
+mctrl_gpio_set(gpios, mctrl):
+	This will sets the gpios according to the mctrl state.
+
+mctrl_gpio_get(gpios, mctrl):
+	This will update mctrl with the gpios values.

drivers/tty/serial/Kconfig +0 -0

index 5d9b01a..95afd31 100644
@@ -1510,4 +1510,7 @@ config SERIAL_ST_ASC_CONSOLE
 

drivers/tty/serial/Kconfig config SERIAL_ST_ASC_CONSOLE · line 1514

Quoted 4 lines

drivers/tty/serial/Kconfig +2 -0

 endmenu
 
+config SERIAL_MCTRL_GPIO
+	tristate

Why is this added here? Who is going to use it?

Handle CTS/DSR/RI/DCD GPIO interrupts in atmel_serial.

Signed-off-by Richard Genoud <[email protected]>

Acked-by Greg Kroah-Hartman <[email protected]>

Acked-by Nicolas Ferre <[email protected]>

---
 drivers/tty/serial/atmel_serial.c |  125 ++++++++++++++++++++++++++++++++++++-
 1 file changed, 122 insertions(+), 3 deletions(-)

drivers/tty/serial/atmel_serial.c +23 -2

index 43ca659..3fceae0 100644
@@ -45,6 +45,7 @@
 #include <linux/gpio.h>
 #include <linux/gpio/consumer.h>
 #include <linux/err.h>
+#include <linux/irq.h>
 
 #include <asm/io.h>
 #include <asm/ioctls.h>

@@ -167,7 +168,9 @@ struct atmel_uart_port {
 
 	struct serial_rs485	rs485;		/* rs485 settings */
 	struct mctrl_gpios	*gpios;
+	int			gpio_irq[UART_GPIO_MAX];
 	unsigned int		tx_done_mask;
+	bool			ms_irq_enabled;
 	bool			is_usart;	/* usart or uart */
 	struct timer_list	uart_timer;	/* uart timer */
 	int (*prepare_rx)(struct uart_port *port);

@@ -489,8 +492,38 @@ static void atmel_stop_rx(struct uart_port *port)
  */
 static void atmel_enable_ms(struct uart_port *port)
 {
-	UART_PUT_IER(port, ATMEL_US_RIIC | ATMEL_US_DSRIC
-			| ATMEL_US_DCDIC | ATMEL_US_CTSIC);
+	struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
+	uint32_t ier = 0;
+
+	/*
+	 * Interrupt should not be enabled twice
+	 */
+	if (atmel_port->ms_irq_enabled)
+		return;
+
+	atmel_port->ms_irq_enabled = true;
+
+	if (atmel_port->gpio_irq[UART_GPIO_CTS] >= 0)
+		enable_irq(atmel_port->gpio_irq[UART_GPIO_CTS]);
+	else
+		ier |= ATMEL_US_CTSIC;
+
+	if (atmel_port->gpio_irq[UART_GPIO_DSR] >= 0)
+		enable_irq(atmel_port->gpio_irq[UART_GPIO_DSR]);
+	else
+		ier |= ATMEL_US_DSRIC;

drivers/tty/serial/atmel_serial.c +89 -1

+
+	UART_PUT_IER(port, ier);
 }
 
 /*

@@ -1079,11 +1112,31 @@ atmel_handle_status(struct uart_port *port, unsigned int pending,
 static irqreturn_t atmel_interrupt(int irq, void *dev_id)
 {
 	struct uart_port *port = dev_id;
+	struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
 	unsigned int status, pending, pass_counter = 0;
+	bool gpio_handled = false;
 
 	do {
 		status = atmel_get_lines_status(port);
 		pending = status & UART_GET_IMR(port);
+		if (!gpio_handled) {
+			/*
+			 * Dealing with GPIO interrupt
+			 */
+			if (irq == atmel_port->gpio_irq[UART_GPIO_CTS])
+				pending |= ATMEL_US_CTSIC;
+
+			if (irq == atmel_port->gpio_irq[UART_GPIO_DSR])
+				pending |= ATMEL_US_DSRIC;
+
+			if (irq == atmel_port->gpio_irq[UART_GPIO_RI])
+				pending |= ATMEL_US_RIIC;
+
+			if (irq == atmel_port->gpio_irq[UART_GPIO_DCD])
+				pending |= ATMEL_US_DCDIC;
+
+			gpio_handled = true;
+		}
 		if (!pending)
 			break;
 

@@ -1563,6 +1616,45 @@ static void atmel_get_ip_name(struct uart_port *port)
 	}
 }
 
+static void atmel_free_gpio_irq(struct uart_port *port)
+{
+	struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
+	enum mctrl_gpio_idx i;
+
+	for (i = 0; i < UART_GPIO_MAX; i++)
+		if (atmel_port->gpio_irq[i] >= 0)
+			free_irq(atmel_port->gpio_irq[i], port);
+}
+
+static int atmel_request_gpio_irq(struct uart_port *port)
+{
+	struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
+	int *irq = atmel_port->gpio_irq;
+	enum mctrl_gpio_idx i;
+	int err = 0;
+
+	for (i = 0; (i < UART_GPIO_MAX) && !err; i++) {
+		if (irq[i] < 0)
+			continue;
+
+		irq_set_status_flags(irq[i], IRQ_NOAUTOEN);
+		err = request_irq(irq[i], atmel_interrupt, IRQ_TYPE_EDGE_BOTH,
+				  "atmel_serial", port);
+		if (err)
+			dev_err(port->dev, "atmel_startup - Can't get %d irq\n",
+				irq[i]);
+	}
+
+	/*
+	 * If something went wrong, rollback.
+	 */
+	while (err && (--i >= 0))
+		if (irq[i] >= 0)
+			free_irq(irq[i], port);
+
+	return err;
+}
+
 /*
  * Perform initialization and enable port for reception
  */

@@ -1579,6 +1671,7 @@ static int atmel_startup(struct uart_port *port)
 	 * handle an unexpected interrupt
 	 */
 	UART_PUT_IDR(port, -1);
+	atmel_port->ms_irq_enabled = false;
 
 	/*
 	 * Allocate the IRQ

@@ -1591,6 +1684,13 @@ static int atmel_startup(struct uart_port *port)
 	}
 
 	/*
+	 * Get the GPIO lines IRQ
+	 */
+	retval = atmel_request_gpio_irq(port);
+	if (retval)
+		goto free_irq;
+
+	/*
 	 * Initialize DMA (if necessary)
 	 */
 	atmel_init_property(atmel_port, pdev);

@@ -1654,6 +1754,11 @@ static int atmel_startup(struct uart_port *port)
 	}
 
 	return 0;
+
+free_irq:
+	free_irq(port->irq, port);
+
+	return retval;
 }
 
 /*

@@ -1701,9 +1806,12 @@ static void atmel_shutdown(struct uart_port *port)
 	atmel_port->rx_ring.tail = 0;
 
 	/*
-	 * Free the interrupt
+	 * Free the interrupts
 	 */
 	free_irq(port->irq, port);
+	atmel_free_gpio_irq(port);
+
+	atmel_port->ms_irq_enabled = false;
 }
 
 /*

@@ -2366,10 +2474,21 @@ static int atmel_serial_resume(struct platform_device *pdev)
 
 static int atmel_init_gpios(struct atmel_uart_port *p, struct device *dev)
 {
+	enum mctrl_gpio_idx i;
+	struct gpio_desc *gpiod;
+
 	p->gpios = mctrl_gpio_init(dev, 0);
 	if (IS_ERR_OR_NULL(p->gpios))
 		return -1;
 
+	for (i = 0; i < UART_GPIO_MAX; i++) {
+		gpiod = mctrl_gpio_to_gpiod(p->gpios, i);
+		if (gpiod && (gpiod_get_direction(gpiod) == GPIOF_DIR_IN))
+			p->gpio_irq[i] = gpiod_to_irq(gpiod);
+		else
+			p->gpio_irq[i] = -EINVAL;
+	}
+
 	return 0;
 }
 

Hi Richard,

Quoted 61 lines

Handle CTS/DSR/RI/DCD GPIO interrupts in atmel_serial.

Signed-off-by Richard Genoud <[email protected]>

Acked-by Greg Kroah-Hartman <[email protected]>

Acked-by Nicolas Ferre <[email protected]>

---
 drivers/tty/serial/atmel_serial.c |  125 ++++++++++++++++++++++++++++++++++++-
 1 file changed, 122 insertions(+), 3 deletions(-)

drivers/tty/serial/atmel_serial.c +27 -2

index 43ca659..3fceae0 100644
@@ -45,6 +45,7 @@
 #include <linux/gpio.h>
 #include <linux/gpio/consumer.h>
 #include <linux/err.h>
+#include <linux/irq.h>
 
 #include <asm/io.h>
 #include <asm/ioctls.h>

@@ -167,7 +168,9 @@ struct atmel_uart_port {
 
      struct serial_rs485     rs485;          /* rs485 settings */
      struct mctrl_gpios      *gpios;
+     int                     gpio_irq[UART_GPIO_MAX];
      unsigned int            tx_done_mask;
+     bool                    ms_irq_enabled;
      bool                    is_usart;       /* usart or uart */
      struct timer_list       uart_timer;     /* uart timer */
      int (*prepare_rx)(struct uart_port *port);

@@ -489,8 +492,38 @@ static void atmel_stop_rx(struct uart_port *port)
  */
 static void atmel_enable_ms(struct uart_port *port)
 {
-     UART_PUT_IER(port, ATMEL_US_RIIC | ATMEL_US_DSRIC
-                     | ATMEL_US_DCDIC | ATMEL_US_CTSIC);
+     struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
+     uint32_t ier = 0;
+
+     /*
+      * Interrupt should not be enabled twice
+      */
+     if (atmel_port->ms_irq_enabled)
+             return;
+
+     atmel_port->ms_irq_enabled = true;
+
+     if (atmel_port->gpio_irq[UART_GPIO_CTS] >= 0)
+             enable_irq(atmel_port->gpio_irq[UART_GPIO_CTS]);
+     else
+             ier |= ATMEL_US_CTSIC;
+
+     if (atmel_port->gpio_irq[UART_GPIO_DSR] >= 0)
+             enable_irq(atmel_port->gpio_irq[UART_GPIO_DSR]);
+     else
+             ier |= ATMEL_US_DSRIC;
+
+     if (atmel_port->gpio_irq[UART_GPIO_RI] >= 0)
+             enable_irq(atmel_port->gpio_irq[UART_GPIO_RI]);
+     else

drivers/tty/serial/atmel_serial.c static void atmel_stop_rx(struct uart_port *port) · line 524

Quoted 6 lines

drivers/tty/serial/atmel_serial.c +6 -0

+             ier |= ATMEL_US_RIIC;
+
+     if (atmel_port->gpio_irq[UART_GPIO_DCD] >= 0)
+             enable_irq(atmel_port->gpio_irq[UART_GPIO_DCD]);
+     else
+             ier |= ATMEL_US_DCDIC;

Where are these gpio irqs disabled if !UART_ENABLE_MS()?

2014-08-10 21:33 GMT+02:00 Peter Hurley <[email protected]>:

Quoted 1 line

Hi Richard,

Hi !
Sorry for the delay !

Quoted 62 lines · Richard Genoud

Quoted 61 lines

Handle CTS/DSR/RI/DCD GPIO interrupts in atmel_serial.

Signed-off-by Richard Genoud <[email protected]>

Acked-by Greg Kroah-Hartman <[email protected]>

Acked-by Nicolas Ferre <[email protected]>

---
 drivers/tty/serial/atmel_serial.c |  125 ++++++++++++++++++++++++++++++++++++-
 1 file changed, 122 insertions(+), 3 deletions(-)

drivers/tty/serial/atmel_serial.c +27 -2

index 43ca659..3fceae0 100644
@@ -45,6 +45,7 @@
 #include <linux/gpio.h>
 #include <linux/gpio/consumer.h>
 #include <linux/err.h>
+#include <linux/irq.h>
 
 #include <asm/io.h>
 #include <asm/ioctls.h>

@@ -167,7 +168,9 @@ struct atmel_uart_port {
 
      struct serial_rs485     rs485;          /* rs485 settings */
      struct mctrl_gpios      *gpios;
+     int                     gpio_irq[UART_GPIO_MAX];
      unsigned int            tx_done_mask;
+     bool                    ms_irq_enabled;
      bool                    is_usart;       /* usart or uart */
      struct timer_list       uart_timer;     /* uart timer */
      int (*prepare_rx)(struct uart_port *port);

@@ -489,8 +492,38 @@ static void atmel_stop_rx(struct uart_port *port)
  */
 static void atmel_enable_ms(struct uart_port *port)
 {
-     UART_PUT_IER(port, ATMEL_US_RIIC | ATMEL_US_DSRIC
-                     | ATMEL_US_DCDIC | ATMEL_US_CTSIC);
+     struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
+     uint32_t ier = 0;
+
+     /*
+      * Interrupt should not be enabled twice
+      */
+     if (atmel_port->ms_irq_enabled)
+             return;
+
+     atmel_port->ms_irq_enabled = true;
+
+     if (atmel_port->gpio_irq[UART_GPIO_CTS] >= 0)
+             enable_irq(atmel_port->gpio_irq[UART_GPIO_CTS]);
+     else
+             ier |= ATMEL_US_CTSIC;
+
+     if (atmel_port->gpio_irq[UART_GPIO_DSR] >= 0)
+             enable_irq(atmel_port->gpio_irq[UART_GPIO_DSR]);
+     else
+             ier |= ATMEL_US_DSRIC;
+
+     if (atmel_port->gpio_irq[UART_GPIO_RI] >= 0)
+             enable_irq(atmel_port->gpio_irq[UART_GPIO_RI]);
+     else

Quoted 8 lines

drivers/tty/serial/atmel_serial.c static void atmel_stop_rx(struct uart_port *port) · line 524

Quoted 6 lines

drivers/tty/serial/atmel_serial.c +6 -0

+             ier |= ATMEL_US_RIIC;
+
+     if (atmel_port->gpio_irq[UART_GPIO_DCD] >= 0)
+             enable_irq(atmel_port->gpio_irq[UART_GPIO_DCD]);
+     else
+             ier |= ATMEL_US_DCDIC;

Where are these gpio irqs disabled if !UART_ENABLE_MS()?

They are disabled in atmel_shutdown()/atmel_free_gpio_irq(). Like the doc says in Documentation/serial/driver
enable_ms(port)
Enable the modem status interrupts.

This method may be called multiple times. Modem status interrupts should be disabled when the shutdown method is called.

Quoted 76 lines

2014-08-10 21:33 GMT+02:00 Peter Hurley <[email protected]>:

Quoted 1 line

Hi Richard,

Hi !
Sorry for the delay !

Quoted 62 lines · Richard Genoud

Quoted 61 lines

Handle CTS/DSR/RI/DCD GPIO interrupts in atmel_serial.

Signed-off-by Richard Genoud <[email protected]>

Acked-by Greg Kroah-Hartman <[email protected]>

Acked-by Nicolas Ferre <[email protected]>

---
 drivers/tty/serial/atmel_serial.c |  125 ++++++++++++++++++++++++++++++++++++-
 1 file changed, 122 insertions(+), 3 deletions(-)

drivers/tty/serial/atmel_serial.c +27 -2

index 43ca659..3fceae0 100644
@@ -45,6 +45,7 @@
 #include <linux/gpio.h>
 #include <linux/gpio/consumer.h>
 #include <linux/err.h>
+#include <linux/irq.h>
 
 #include <asm/io.h>
 #include <asm/ioctls.h>

@@ -167,7 +168,9 @@ struct atmel_uart_port {
 
      struct serial_rs485     rs485;          /* rs485 settings */
      struct mctrl_gpios      *gpios;
+     int                     gpio_irq[UART_GPIO_MAX];
      unsigned int            tx_done_mask;
+     bool                    ms_irq_enabled;
      bool                    is_usart;       /* usart or uart */
      struct timer_list       uart_timer;     /* uart timer */
      int (*prepare_rx)(struct uart_port *port);

@@ -489,8 +492,38 @@ static void atmel_stop_rx(struct uart_port *port)
  */
 static void atmel_enable_ms(struct uart_port *port)
 {
-     UART_PUT_IER(port, ATMEL_US_RIIC | ATMEL_US_DSRIC
-                     | ATMEL_US_DCDIC | ATMEL_US_CTSIC);
+     struct atmel_uart_port *atmel_port = to_atmel_uart_port(port);
+     uint32_t ier = 0;
+
+     /*
+      * Interrupt should not be enabled twice
+      */
+     if (atmel_port->ms_irq_enabled)
+             return;
+
+     atmel_port->ms_irq_enabled = true;
+
+     if (atmel_port->gpio_irq[UART_GPIO_CTS] >= 0)
+             enable_irq(atmel_port->gpio_irq[UART_GPIO_CTS]);
+     else
+             ier |= ATMEL_US_CTSIC;
+
+     if (atmel_port->gpio_irq[UART_GPIO_DSR] >= 0)
+             enable_irq(atmel_port->gpio_irq[UART_GPIO_DSR]);
+     else
+             ier |= ATMEL_US_DSRIC;
+
+     if (atmel_port->gpio_irq[UART_GPIO_RI] >= 0)
+             enable_irq(atmel_port->gpio_irq[UART_GPIO_RI]);
+     else

Quoted 8 lines

drivers/tty/serial/atmel_serial.c static void atmel_stop_rx(struct uart_port *port) · line 524

Quoted 6 lines

drivers/tty/serial/atmel_serial.c +6 -0

+             ier |= ATMEL_US_RIIC;
+
+     if (atmel_port->gpio_irq[UART_GPIO_DCD] >= 0)
+             enable_irq(atmel_port->gpio_irq[UART_GPIO_DCD]);
+     else
+             ier |= ATMEL_US_DCDIC;

Where are these gpio irqs disabled if !UART_ENABLE_MS()?

Quoted 8 lines

They are disabled in atmel_shutdown()/atmel_free_gpio_irq(). Like the doc says in Documentation/serial/driver
enable_ms(port)
Enable the modem status interrupts.

This method may be called multiple times. Modem status interrupts should be disabled when the shutdown method is called.

Thanks for replying.

The point of the UART_ENABLE_MS() macro is to allow the UART driver to determine if modem status interrupts need to be enabled when handling the .set_termios() method.

When handling set_termios(), if UART_ENABLE_MS is false (ie., the serial core does not require modem status interrupts), the UART driver can and should turn modem status interrupts off.

It is _also_ true that "modem status interrupts should be disabled when the shutdown method is called"; in fact, _all_ UART-sourced interrupts should be disabled when the shutdown method is called.