Commit 84130aac authored by Richard Genoud's avatar Richard Genoud Committed by Greg Kroah-Hartman
Browse files

tty/serial: Add GPIOLIB helpers for controlling modem lines 



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: default avatarRichard Genoud <richard.genoud@gmail.com>
Acked-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
Tested-by: default avatarYegor Yefremov <yegorslists@googlemail.com>
Signed-off-by: default avatarGreg Kroah-Hartman <gregkh@linuxfoundation.org>
parent fa390932

Documentation/serial/driver

+25 −0
Original line number Diff line number Diff line
@@ -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
Original line number Diff line number Diff line
@@ -1553,4 +1553,7 @@ config SERIAL_MEN_Z135 


endmenu



config SERIAL_MCTRL_GPIO

	tristate



endif # TTY

drivers/tty/serial/Makefile

+3 −0
Original line number Diff line number Diff line
@@ -92,3 +92,6 @@ obj-$(CONFIG_SERIAL_ARC) += arc_uart.o 
obj-$(CONFIG_SERIAL_RP2)	+= rp2.o

obj-$(CONFIG_SERIAL_FSL_LPUART)	+= fsl_lpuart.o

obj-$(CONFIG_SERIAL_MEN_Z135)	+= men_z135_uart.o



# GPIOLIB helpers for modem control lines

obj-$(CONFIG_SERIAL_MCTRL_GPIO)	+= serial_mctrl_gpio.o

drivers/tty/serial/serial_mctrl_gpio.c

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Original line number Diff line number Diff line 
/*

 * 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

0 → 100644
+110 −0
Original line number Diff line number Diff line 
/*

 * 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

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