136 lines
3.1 KiB
C
136 lines
3.1 KiB
C
// 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 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.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>");
|