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Commit 2a0b0a57 authored by Linus Walleij's avatar Linus Walleij
Browse files

gpio: Add a Gateworks PLD GPIO driver 



This adds a driver for Gateworks PLD GPIO, that exist in
two instances on the Gateworks Cambria GW2358-4 router
platform at least.

Cc: Imre Kaloz <kaloz@openwrt.org>
Cc: Tim Harvey <tharvey@gateworks.com>
Reviewed-by: default avatarBartosz Golaszewski <bgolaszewski@baylibre.com>
Signed-off-by: default avatarLinus Walleij <linus.walleij@linaro.org>
parent 35b21b6e

drivers/gpio/Kconfig

+7 −0
Original line number Diff line number Diff line
@@ -831,6 +831,13 @@ config GPIO_ADNP 
	  enough to represent all pins, but the driver will assume a

	  register layout for 64 pins (8 registers).



config GPIO_GW_PLD

	tristate "Gateworks PLD GPIO Expander"

	depends on OF_GPIO

	help

	  Say yes here to provide access to the Gateworks I2C PLD GPIO

	  Expander. This is used at least on the Cambria GW2358-4.



config GPIO_MAX7300

	tristate "Maxim MAX7300 GPIO expander"

	select GPIO_MAX730X

drivers/gpio/Makefile

+1 −0
Original line number Diff line number Diff line
@@ -55,6 +55,7 @@ obj-$(CONFIG_GPIO_FTGPIO010) += gpio-ftgpio010.o 
obj-$(CONFIG_GPIO_GE_FPGA)	+= gpio-ge.o

obj-$(CONFIG_GPIO_GPIO_MM)	+= gpio-gpio-mm.o

obj-$(CONFIG_GPIO_GRGPIO)	+= gpio-grgpio.o

obj-$(CONFIG_GPIO_GW_PLD)	+= gpio-gw-pld.o

obj-$(CONFIG_GPIO_HLWD)		+= gpio-hlwd.o

obj-$(CONFIG_HTC_EGPIO)		+= gpio-htc-egpio.o

obj-$(CONFIG_GPIO_ICH)		+= gpio-ich.o

drivers/gpio/gpio-gw-pld.c

0 → 100644
+137 −0
Original line number Diff line number Diff line 
// SPDX-License-Identifier: GPL-2.0+

//

// Gateworks I2C PLD GPIO expander

//

// Copyright (C) 2019 Linus Walleij <linus.walleij@linaro.org>

//

// Based on code and know-how from the OpenWrt driver:

// Copyright (C) 2009 Gateworks Corporation

// Authors: Chris Lang, Imre Kaloz



#include <linux/bits.h>

#include <linux/kernel.h>

#include <linux/slab.h>

#include <linux/gpio/driver.h>

#include <linux/i2c.h>

#include <linux/module.h>



/**

 * struct gw_pld - State container for Gateworks PLD

 * @chip: GPIO chip instance

 * @client: I2C client

 * @out: shadow register for the output bute

 */

struct gw_pld {

	struct gpio_chip chip;

	struct i2c_client *client;

	u8 out;

};



/*

 * The Gateworks I2C PLD chip only expose one read and one write register.

 * Writing a "one" bit (to match the reset state) lets that pin be used as an

 * input. It is an open-drain model.

 */

static int gw_pld_input8(struct gpio_chip *gc, unsigned offset)

{

	struct gw_pld *gw = gpiochip_get_data(gc);



	gw->out |= BIT(offset);

	return i2c_smbus_write_byte(gw->client, gw->out);

}



static int gw_pld_get8(struct gpio_chip *gc, unsigned offset)

{

	struct gw_pld *gw = gpiochip_get_data(gc);

	s32 val;



	val = i2c_smbus_read_byte(gw->client);



	return (val < 0) ? 0 : !!(val & BIT(offset));

}



static int gw_pld_output8(struct gpio_chip *gc, unsigned offset, int value)

{

	struct gw_pld *gw = gpiochip_get_data(gc);



	if (value)

		gw->out |= BIT(offset);

	else

		gw->out &= ~BIT(offset);



	return i2c_smbus_write_byte(gw->client, gw->out);

}



static void gw_pld_set8(struct gpio_chip *gc, unsigned offset, int value)

{

	gw_pld_output8(gc, offset, value);

}



static int gw_pld_probe(struct i2c_client *client,

			const struct i2c_device_id *id)

{

	struct device *dev = &client->dev;

	struct device_node *np = dev->of_node;

	struct gw_pld *gw;

	int ret;



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

	if (!gw)

		return -ENOMEM;



	gw->chip.base = -1;

	gw->chip.can_sleep = true;

	gw->chip.parent = dev;

	gw->chip.of_node = np;

	gw->chip.owner = THIS_MODULE;

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

	gw->chip.ngpio = 8;

	gw->chip.direction_input = gw_pld_input8;

	gw->chip.get = gw_pld_get8;

	gw->chip.direction_output = gw_pld_output8;

	gw->chip.set = gw_pld_set8;

	gw->client = client;



	/*

	 * The Gateworks I2C PLD chip does not properly send the acknowledge

	 * bit at all times, but we can still use the standard i2c_smbus

	 * functions by simply ignoring this bit.

	 */

	client->flags |= I2C_M_IGNORE_NAK;

	gw->out = 0xFF;



	i2c_set_clientdata(client, gw);



	ret = devm_gpiochip_add_data(dev, &gw->chip, gw);

	if (ret)

		return ret;



	dev_info(dev, "registered Gateworks PLD GPIO device\n");



	return 0;

}



static const struct i2c_device_id gw_pld_id[] = {

	{ "gw-pld", },

	{ }

};

MODULE_DEVICE_TABLE(i2c, gw_pld_id);



static const struct of_device_id gw_pld_dt_ids[] = {

	{ .compatible = "gateworks,pld-gpio", },

	{ },

};

MODULE_DEVICE_TABLE(of, gw_pld_dt_ids);



static struct i2c_driver gw_pld_driver = {

	.driver = {

		.name = "gw_pld",

		.of_match_table = gw_pld_dt_ids,

	},

	.probe = gw_pld_probe,

	.id_table = gw_pld_id,

};

module_i2c_driver(gw_pld_driver);



MODULE_LICENSE("GPL");

MODULE_AUTHOR("Linus Walleij <linus.walleij@linaro.org>");