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// SPDX-License-Identifier: GPL-2.0-only
/*
* w1-gpio - GPIO w1 bus master driver
*
* Copyright (C) 2007 Ville Syrjala <syrjala@sci.fi>
*/
#include <linux/init.h>
#include <linux/module.h>
#include <linux/platform_device.h>
#include <linux/slab.h>
#include <linux/gpio/consumer.h>
#include <linux/of_platform.h>
#include <linux/err.h>
#include <linux/of.h>
#include <linux/delay.h>
#include <linux/w1.h>
struct w1_gpio_ddata {
struct gpio_desc *gpiod;
struct gpio_desc *pullup_gpiod;
unsigned int pullup_duration;
};
static u8 w1_gpio_set_pullup(void *data, int delay)
{
struct w1_gpio_ddata *ddata = data;
if (delay) {
ddata->pullup_duration = delay;
} else {
if (ddata->pullup_duration) {
/*
* This will OVERRIDE open drain emulation and force-pull
* the line high for some time.
*/
gpiod_set_raw_value(ddata->gpiod, 1);
msleep(ddata->pullup_duration);
/*
* This will simply set the line as input since we are doing
* open drain emulation in the GPIO library.
*/
gpiod_set_value(ddata->gpiod, 1);
}
ddata->pullup_duration = 0;
}
return 0;
}
static void w1_gpio_write_bit(void *data, u8 bit)
{
struct w1_gpio_ddata *ddata = data;
gpiod_set_value(ddata->gpiod, bit);
}
static u8 w1_gpio_read_bit(void *data)
{
struct w1_gpio_ddata *ddata = data;
return gpiod_get_value(ddata->gpiod) ? 1 : 0;
}
#if defined(CONFIG_OF)
static const struct of_device_id w1_gpio_dt_ids[] = {
{ .compatible = "w1-gpio" },
{}
};
MODULE_DEVICE_TABLE(of, w1_gpio_dt_ids);
#endif
static int w1_gpio_probe(struct platform_device *pdev)
{
struct w1_bus_master *master;
struct w1_gpio_ddata *ddata;
struct device *dev = &pdev->dev;
struct device_node *np = dev->of_node;
/* Enforce open drain mode by default */
enum gpiod_flags gflags = GPIOD_OUT_LOW_OPEN_DRAIN;
int err;
ddata = devm_kzalloc(&pdev->dev, sizeof(*ddata), GFP_KERNEL);
if (!ddata)
return -ENOMEM;
/*
* This parameter means that something else than the gpiolib has
* already set the line into open drain mode, so we should just
* driver it high/low like we are in full control of the line and
* open drain will happen transparently.
*/
if (of_property_present(np, "linux,open-drain"))
gflags = GPIOD_OUT_LOW;
master = devm_kzalloc(dev, sizeof(struct w1_bus_master),
GFP_KERNEL);
if (!master)
return -ENOMEM;
ddata->gpiod = devm_gpiod_get_index(dev, NULL, 0, gflags);
if (IS_ERR(ddata->gpiod)) {
dev_err(dev, "gpio_request (pin) failed\n");
return PTR_ERR(ddata->gpiod);
}
ddata->pullup_gpiod =
devm_gpiod_get_index_optional(dev, NULL, 1, GPIOD_OUT_LOW);
if (IS_ERR(ddata->pullup_gpiod)) {
dev_err(dev, "gpio_request_one "
"(ext_pullup_enable_pin) failed\n");
return PTR_ERR(ddata->pullup_gpiod);
}
master->data = ddata;
master->read_bit = w1_gpio_read_bit;
gpiod_direction_output(ddata->gpiod, 1);
master->write_bit = w1_gpio_write_bit;
/*
* If we are using open drain emulation from the GPIO library,
* we need to use this pullup function that hammers the line
* high using a raw accessor to provide pull-up for the w1
* line.
*/
if (gflags == GPIOD_OUT_LOW_OPEN_DRAIN)
master->set_pullup = w1_gpio_set_pullup;
err = w1_add_master_device(master);
if (err) {
dev_err(dev, "w1_add_master device failed\n");
return err;
}
if (ddata->pullup_gpiod)
gpiod_set_value(ddata->pullup_gpiod, 1);
platform_set_drvdata(pdev, master);
return 0;
}
static int w1_gpio_remove(struct platform_device *pdev)
{
struct w1_bus_master *master = platform_get_drvdata(pdev);
struct w1_gpio_ddata *ddata = master->data;
if (ddata->pullup_gpiod)
gpiod_set_value(ddata->pullup_gpiod, 0);
w1_remove_master_device(master);
return 0;
}
static struct platform_driver w1_gpio_driver = {
.driver = {
.name = "w1-gpio",
.of_match_table = of_match_ptr(w1_gpio_dt_ids),
},
.probe = w1_gpio_probe,
.remove = w1_gpio_remove,
};
module_platform_driver(w1_gpio_driver);
MODULE_DESCRIPTION("GPIO w1 bus master driver");
MODULE_AUTHOR("Ville Syrjala <syrjala@sci.fi>");
MODULE_LICENSE("GPL");
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