Commit 856ed97a authored by Marek Behún's avatar Marek Behún Committed by Arnd Bergmann
Browse files

drivers: gpio: Add support for GPIOs over Moxtet bus 

This adds support for interpreting the input and output bits of one
device on Moxtet bus as GPIOs.
This is needed for example by the SFP cage module of Turris Mox.

Link: https://lore.kernel.org/r/20190812161118.21476-5-marek.behun@nic.cz


Signed-off-by: default avatarMarek Behún <marek.behun@nic.cz>
Reviewed-by: default avatarLinus Walleij <linus.walleij@linaro.org>
Signed-off-by: default avatarArnd Bergmann <arnd@arndb.de>
parent 2091b417

MAINTAINERS

+1 −0
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@@ -1635,6 +1635,7 @@ F: Documentation/ABI/testing/sysfs-bus-moxtet-devices 
F:	Documentation/devicetree/bindings/bus/moxtet.txt

F:	include/linux/moxtet.h

F:	drivers/bus/moxtet.c

F:	drivers/gpio/gpio-moxtet.c



ARM/EBSA110 MACHINE SUPPORT

M:	Russell King <linux@armlinux.org.uk>

drivers/gpio/Kconfig

+9 −0
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@@ -1445,6 +1445,15 @@ config GPIO_XRA1403 
	help

	  GPIO driver for EXAR XRA1403 16-bit SPI-based GPIO expander.



config GPIO_MOXTET

	tristate "Turris Mox Moxtet bus GPIO expander"

	depends on MOXTET

	help

	  Say yes here if you are building for the Turris Mox router.

	  This is the driver needed for configuring the GPIOs via the Moxtet

	  bus. For example the Mox module with SFP cage needs this driver

	  so that phylink can use corresponding GPIOs.



endmenu



menu "USB GPIO expanders"

drivers/gpio/Makefile

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@@ -93,6 +93,7 @@ obj-$(CONFIG_GPIO_ML_IOH) += gpio-ml-ioh.o 
obj-$(CONFIG_GPIO_MLXBF)		+= gpio-mlxbf.o

obj-$(CONFIG_GPIO_MM_LANTIQ)		+= gpio-mm-lantiq.o

obj-$(CONFIG_GPIO_MOCKUP)		+= gpio-mockup.o

obj-$(CONFIG_GPIO_MOXTET)		+= gpio-moxtet.o

obj-$(CONFIG_GPIO_MPC5200)		+= gpio-mpc5200.o

obj-$(CONFIG_GPIO_MPC8XXX)		+= gpio-mpc8xxx.o

obj-$(CONFIG_GPIO_MSIC)			+= gpio-msic.o

drivers/gpio/gpio-moxtet.c

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+179 −0
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// SPDX-License-Identifier: GPL-2.0

/*

 *  Turris Mox Moxtet GPIO expander

 *

 *  Copyright (C) 2018 Marek Behun <marek.behun@nic.cz>

 */



#include <linux/bitops.h>

#include <linux/gpio/driver.h>

#include <linux/moxtet.h>

#include <linux/module.h>



#define MOXTET_GPIO_NGPIOS	12

#define MOXTET_GPIO_INPUTS	4



struct moxtet_gpio_desc {

	u16 in_mask;

	u16 out_mask;

};



static const struct moxtet_gpio_desc descs[] = {

	[TURRIS_MOX_MODULE_SFP] = {

		.in_mask = GENMASK(2, 0),

		.out_mask = GENMASK(5, 4),

	},

};



struct moxtet_gpio_chip {

	struct device			*dev;

	struct gpio_chip		gpio_chip;

	const struct moxtet_gpio_desc	*desc;

};



static int moxtet_gpio_get_value(struct gpio_chip *gc, unsigned int offset)

{

	struct moxtet_gpio_chip *chip = gpiochip_get_data(gc);

	int ret;



	if (chip->desc->in_mask & BIT(offset)) {

		ret = moxtet_device_read(chip->dev);

	} else if (chip->desc->out_mask & BIT(offset)) {

		ret = moxtet_device_written(chip->dev);

		if (ret >= 0)

			ret <<= MOXTET_GPIO_INPUTS;

	} else {

		return -EINVAL;

	}



	if (ret < 0)

		return ret;



	return !!(ret & BIT(offset));

}



static void moxtet_gpio_set_value(struct gpio_chip *gc, unsigned int offset,

				  int val)

{

	struct moxtet_gpio_chip *chip = gpiochip_get_data(gc);

	int state;



	state = moxtet_device_written(chip->dev);

	if (state < 0)

		return;



	offset -= MOXTET_GPIO_INPUTS;



	if (val)

		state |= BIT(offset);

	else

		state &= ~BIT(offset);



	moxtet_device_write(chip->dev, state);

}



static int moxtet_gpio_get_direction(struct gpio_chip *gc, unsigned int offset)

{

	struct moxtet_gpio_chip *chip = gpiochip_get_data(gc);



	/* All lines are hard wired to be either input or output, not both. */

	if (chip->desc->in_mask & BIT(offset))

		return 1;

	else if (chip->desc->out_mask & BIT(offset))

		return 0;

	else

		return -EINVAL;

}



static int moxtet_gpio_direction_input(struct gpio_chip *gc,

				       unsigned int offset)

{

	struct moxtet_gpio_chip *chip = gpiochip_get_data(gc);



	if (chip->desc->in_mask & BIT(offset))

		return 0;

	else if (chip->desc->out_mask & BIT(offset))

		return -ENOTSUPP;

	else

		return -EINVAL;

}



static int moxtet_gpio_direction_output(struct gpio_chip *gc,

					unsigned int offset, int val)

{

	struct moxtet_gpio_chip *chip = gpiochip_get_data(gc);



	if (chip->desc->out_mask & BIT(offset))

		moxtet_gpio_set_value(gc, offset, val);

	else if (chip->desc->in_mask & BIT(offset))

		return -ENOTSUPP;

	else

		return -EINVAL;



	return 0;

}



static int moxtet_gpio_probe(struct device *dev)

{

	struct moxtet_gpio_chip *chip;

	struct device_node *nc = dev->of_node;

	int id;



	id = to_moxtet_device(dev)->id;



	if (id >= ARRAY_SIZE(descs)) {

		dev_err(dev, "%pOF Moxtet device id 0x%x is not supported by gpio-moxtet driver\n",

			nc, id);

		return -ENOTSUPP;

	}



	chip = devm_kzalloc(dev, sizeof(*chip), GFP_KERNEL);

	if (!chip)

		return -ENOMEM;



	chip->dev = dev;

	chip->gpio_chip.parent = dev;

	chip->desc = &descs[id];



	dev_set_drvdata(dev, chip);



	chip->gpio_chip.label = dev_name(dev);

	chip->gpio_chip.get_direction = moxtet_gpio_get_direction;

	chip->gpio_chip.direction_input = moxtet_gpio_direction_input;

	chip->gpio_chip.direction_output = moxtet_gpio_direction_output;

	chip->gpio_chip.get = moxtet_gpio_get_value;

	chip->gpio_chip.set = moxtet_gpio_set_value;

	chip->gpio_chip.base = -1;



	chip->gpio_chip.ngpio = MOXTET_GPIO_NGPIOS;



	chip->gpio_chip.can_sleep = true;

	chip->gpio_chip.owner = THIS_MODULE;



	return devm_gpiochip_add_data(dev, &chip->gpio_chip, chip);

}



static const struct of_device_id moxtet_gpio_dt_ids[] = {

	{ .compatible = "cznic,moxtet-gpio", },

	{},

};

MODULE_DEVICE_TABLE(of, moxtet_gpio_dt_ids);



static const enum turris_mox_module_id moxtet_gpio_module_table[] = {

	TURRIS_MOX_MODULE_SFP,

	0,

};



static struct moxtet_driver moxtet_gpio_driver = {

	.driver = {

		.name		= "moxtet-gpio",

		.of_match_table	= moxtet_gpio_dt_ids,

		.probe		= moxtet_gpio_probe,

	},

	.id_table = moxtet_gpio_module_table,

};

module_moxtet_driver(moxtet_gpio_driver);



MODULE_AUTHOR("Marek Behun <marek.behun@nic.cz>");

MODULE_DESCRIPTION("Turris Mox Moxtet GPIO expander");

MODULE_LICENSE("GPL v2");

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