Commit 03810031 authored by Emanuele Ghidoli's avatar Emanuele Ghidoli Committed by Bartosz Golaszewski
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gpio: fxl6408: add I2C GPIO expander driver 

Add minimal driver for Fairchild FXL6408 8-bit I2C-controlled GPIO expander
using the generic regmap based GPIO driver (GPIO_REGMAP).

The driver implements setting the GPIO direction, reading inputs
and writing outputs.

In addition to that the FXL6408 has the following functionalities:
- allows to monitor input ports for data transitions with an interrupt pin
- all inputs can be configured with pull-up or pull-down resistors

Datasheet: https://www.onsemi.com/download/data-sheet/pdf/fxl6408-d.pdf


Signed-off-by: default avatarEmanuele Ghidoli <emanuele.ghidoli@toradex.com>
Co-developed-by: default avatarFrancesco Dolcini <francesco.dolcini@toradex.com>
Signed-off-by: default avatarFrancesco Dolcini <francesco.dolcini@toradex.com>
Reviewed-by: default avatarAndy Shevchenko <andy.shevchenko@gmail.com>
[Bartosz: order includes alphabetically]
Signed-off-by: default avatarBartosz Golaszewski <bartosz.golaszewski@linaro.org>
parent d41116f7

drivers/gpio/Kconfig

+10 −0
Original line number Diff line number Diff line
@@ -1007,6 +1007,16 @@ config GPIO_ADNP 
	  enough to represent all pins, but the driver will assume a

	  register layout for 64 pins (8 registers).



config GPIO_FXL6408

	tristate "FXL6408 I2C GPIO expander"

	select GPIO_REGMAP

	select REGMAP_I2C

	help

	  GPIO driver for Fairchild Semiconductor FXL6408 GPIO expander.



	  To compile this driver as a module, choose M here: the module will

	  be called gpio-fxl6408.



config GPIO_GW_PLD

	tristate "Gateworks PLD GPIO Expander"

	depends on OF_GPIO

drivers/gpio/Makefile

+1 −0
Original line number Diff line number Diff line
@@ -60,6 +60,7 @@ obj-$(CONFIG_GPIO_EP93XX) += gpio-ep93xx.o 
obj-$(CONFIG_GPIO_EXAR)			+= gpio-exar.o

obj-$(CONFIG_GPIO_F7188X)		+= gpio-f7188x.o

obj-$(CONFIG_GPIO_FTGPIO010)		+= gpio-ftgpio010.o

obj-$(CONFIG_GPIO_FXL6408)		+= gpio-fxl6408.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

drivers/gpio/gpio-fxl6408.c

0 → 100644
+158 −0
Original line number Diff line number Diff line 
// SPDX-License-Identifier: GPL-2.0-only

/*

 * FXL6408 GPIO driver

 *

 * Copyright 2023 Toradex

 *

 * Author: Emanuele Ghidoli <emanuele.ghidoli@toradex.com>

 */



#include <linux/err.h>

#include <linux/gpio/regmap.h>

#include <linux/i2c.h>

#include <linux/kernel.h>

#include <linux/module.h>

#include <linux/regmap.h>



#define FXL6408_REG_DEVICE_ID		0x01

#define FXL6408_MF_FAIRCHILD		0b101

#define FXL6408_MF_SHIFT		5



/* Bits set here indicate that the GPIO is an output. */

#define FXL6408_REG_IO_DIR		0x03



/*

 * Bits set here, when the corresponding bit of IO_DIR is set, drive

 * the output high instead of low.

 */

#define FXL6408_REG_OUTPUT		0x05



/* Bits here make the output High-Z, instead of the OUTPUT value. */

#define FXL6408_REG_OUTPUT_HIGH_Z	0x07



/* Returns the current status (1 = HIGH) of the input pins. */

#define FXL6408_REG_INPUT_STATUS	0x0f



/*

 * Return the current interrupt status

 * This bit is HIGH if input GPIO != default state (register 09h).

 * The flag is cleared after being read (bit returns to 0).

 * The input must go back to default state and change again before this flag is raised again.

 */

#define FXL6408_REG_INT_STS		0x13



#define FXL6408_NGPIO			8



static const struct regmap_range rd_range[] = {

	{ FXL6408_REG_DEVICE_ID, FXL6408_REG_DEVICE_ID },

	{ FXL6408_REG_IO_DIR, FXL6408_REG_OUTPUT },

	{ FXL6408_REG_INPUT_STATUS, FXL6408_REG_INPUT_STATUS },

};



static const struct regmap_range wr_range[] = {

	{ FXL6408_REG_DEVICE_ID, FXL6408_REG_DEVICE_ID },

	{ FXL6408_REG_IO_DIR, FXL6408_REG_OUTPUT },

	{ FXL6408_REG_OUTPUT_HIGH_Z, FXL6408_REG_OUTPUT_HIGH_Z },

};



static const struct regmap_range volatile_range[] = {

	{ FXL6408_REG_DEVICE_ID, FXL6408_REG_DEVICE_ID },

	{ FXL6408_REG_INPUT_STATUS, FXL6408_REG_INPUT_STATUS },

};



static const struct regmap_access_table rd_table = {

	.yes_ranges = rd_range,

	.n_yes_ranges = ARRAY_SIZE(rd_range),

};



static const struct regmap_access_table wr_table = {

	.yes_ranges = wr_range,

	.n_yes_ranges = ARRAY_SIZE(wr_range),

};



static const struct regmap_access_table volatile_table = {

	.yes_ranges = volatile_range,

	.n_yes_ranges = ARRAY_SIZE(volatile_range),

};



static const struct regmap_config regmap = {

	.reg_bits = 8,

	.val_bits = 8,



	.max_register = FXL6408_REG_INT_STS,

	.wr_table = &wr_table,

	.rd_table = &rd_table,

	.volatile_table = &volatile_table,



	.cache_type = REGCACHE_RBTREE,

	.num_reg_defaults_raw = FXL6408_REG_INT_STS + 1,

};



static int fxl6408_identify(struct device *dev, struct regmap *regmap)

{

	int val, ret;



	ret = regmap_read(regmap, FXL6408_REG_DEVICE_ID, &val);

	if (ret)

		return dev_err_probe(dev, ret, "error reading DEVICE_ID\n");

	if (val >> FXL6408_MF_SHIFT != FXL6408_MF_FAIRCHILD)

		return dev_err_probe(dev, -ENODEV, "invalid device id 0x%02x\n", val);



	return 0;

}



static int fxl6408_probe(struct i2c_client *client)

{

	struct device *dev = &client->dev;

	int ret;

	struct gpio_regmap_config gpio_config = {

		.parent = dev,

		.ngpio = FXL6408_NGPIO,

		.reg_dat_base = GPIO_REGMAP_ADDR(FXL6408_REG_INPUT_STATUS),

		.reg_set_base = GPIO_REGMAP_ADDR(FXL6408_REG_OUTPUT),

		.reg_dir_out_base = GPIO_REGMAP_ADDR(FXL6408_REG_IO_DIR),

		.ngpio_per_reg = FXL6408_NGPIO,

	};



	gpio_config.regmap = devm_regmap_init_i2c(client, &regmap);

	if (IS_ERR(gpio_config.regmap))

		return dev_err_probe(dev, PTR_ERR(gpio_config.regmap),

				     "failed to allocate register map\n");



	ret = fxl6408_identify(dev, gpio_config.regmap);

	if (ret)

		return ret;



	/* Disable High-Z of outputs, so that our OUTPUT updates actually take effect. */

	ret = regmap_write(gpio_config.regmap, FXL6408_REG_OUTPUT_HIGH_Z, 0);

	if (ret)

		return dev_err_probe(dev, ret, "failed to write 'output high Z' register\n");



	return PTR_ERR_OR_ZERO(devm_gpio_regmap_register(dev, &gpio_config));

}



static const __maybe_unused struct of_device_id fxl6408_dt_ids[] = {

	{ .compatible = "fcs,fxl6408" },

	{ }

};

MODULE_DEVICE_TABLE(of, fxl6408_dt_ids);



static const struct i2c_device_id fxl6408_id[] = {

	{ "fxl6408", 0 },

	{ }

};

MODULE_DEVICE_TABLE(i2c, fxl6408_id);



static struct i2c_driver fxl6408_driver = {

	.driver = {

		.name	= "fxl6408",

		.of_match_table = fxl6408_dt_ids,

	},

	.probe_new	= fxl6408_probe,

	.id_table	= fxl6408_id,

};

module_i2c_driver(fxl6408_driver);



MODULE_AUTHOR("Emanuele Ghidoli <emanuele.ghidoli@toradex.com>");

MODULE_DESCRIPTION("FXL6408 GPIO driver");

MODULE_LICENSE("GPL");