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/*
* GPIO Reset Controller driver
*
* Copyright 2013 Philipp Zabel, Pengutronix
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*/
#include <linux/delay.h>
#include <linux/err.h>
#include <linux/gpio.h>
#include <linux/module.h>
#include <linux/of_gpio.h>
#include <linux/platform_device.h>
#include <linux/reset-controller.h>
struct gpio_reset_data {
struct reset_controller_dev rcdev;
unsigned int gpio;
bool active_low;
s32 delay_us;
};
static void gpio_reset_set(struct reset_controller_dev *rcdev, int asserted)
{
struct gpio_reset_data *drvdata = container_of(rcdev,
struct gpio_reset_data, rcdev);
int value = asserted;
if (drvdata->active_low)
value = !value;
gpio_set_value(drvdata->gpio, value);
}
static int gpio_reset(struct reset_controller_dev *rcdev, unsigned long id)
{
struct gpio_reset_data *drvdata = container_of(rcdev,
struct gpio_reset_data, rcdev);
if (drvdata->delay_us < 0)
return -ENOSYS;
gpio_reset_set(rcdev, 1);
udelay(drvdata->delay_us);
gpio_reset_set(rcdev, 0);
return 0;
}
static int gpio_reset_assert(struct reset_controller_dev *rcdev,
unsigned long id)
{
gpio_reset_set(rcdev, 1);
return 0;
}
static int gpio_reset_deassert(struct reset_controller_dev *rcdev,
unsigned long id)
{
gpio_reset_set(rcdev, 0);
return 0;
}
static struct reset_control_ops gpio_reset_ops = {
.reset = gpio_reset,
.assert = gpio_reset_assert,
.deassert = gpio_reset_deassert,
};
static int of_gpio_reset_xlate(struct reset_controller_dev *rcdev,
const struct of_phandle_args *reset_spec)
{
if (WARN_ON(reset_spec->args_count != 0))
return -EINVAL;
return 0;
}
static int gpio_reset_probe(struct platform_device *pdev)
{
struct device_node *np = pdev->dev.of_node;
struct gpio_reset_data *drvdata;
enum of_gpio_flags flags;
unsigned long gpio_flags;
bool initially_in_reset;
int ret;
drvdata = devm_kzalloc(&pdev->dev, sizeof(*drvdata), GFP_KERNEL);
if (drvdata == NULL)
return -ENOMEM;
if (of_gpio_named_count(np, "reset-gpios") != 1) {
dev_err(&pdev->dev,
"reset-gpios property missing, or not a single gpio\n");
return -EINVAL;
}
drvdata->gpio = of_get_named_gpio_flags(np, "reset-gpios", 0, &flags);
if (drvdata->gpio == -EPROBE_DEFER) {
return drvdata->gpio;
} else if (!gpio_is_valid(drvdata->gpio)) {
dev_err(&pdev->dev, "invalid reset gpio: %d\n", drvdata->gpio);
return drvdata->gpio;
}
drvdata->active_low = flags & OF_GPIO_ACTIVE_LOW;
ret = of_property_read_u32(np, "reset-delay-us", &drvdata->delay_us);
if (ret < 0)
drvdata->delay_us = -1;
else if (drvdata->delay_us < 0)
dev_warn(&pdev->dev, "reset delay too high\n");
initially_in_reset = of_property_read_bool(np, "initially-in-reset");
if (drvdata->active_low ^ initially_in_reset)
gpio_flags = GPIOF_OUT_INIT_HIGH;
else
gpio_flags = GPIOF_OUT_INIT_LOW;
ret = devm_gpio_request_one(&pdev->dev, drvdata->gpio, gpio_flags, NULL);
if (ret < 0) {
dev_err(&pdev->dev, "failed to request gpio %d: %d\n",
drvdata->gpio, ret);
return ret;
}
platform_set_drvdata(pdev, drvdata);
drvdata->rcdev.of_node = np;
drvdata->rcdev.owner = THIS_MODULE;
drvdata->rcdev.nr_resets = 1;
drvdata->rcdev.ops = &gpio_reset_ops;
drvdata->rcdev.of_xlate = of_gpio_reset_xlate;
reset_controller_register(&drvdata->rcdev);
return 0;
}
static int gpio_reset_remove(struct platform_device *pdev)
{
struct gpio_reset_data *drvdata = platform_get_drvdata(pdev);
reset_controller_unregister(&drvdata->rcdev);
return 0;
}
static struct of_device_id gpio_reset_dt_ids[] = {
{ .compatible = "gpio-reset" },
{ }
};
static struct platform_driver gpio_reset_driver = {
.probe = gpio_reset_probe,
.remove = gpio_reset_remove,
.driver = {
.name = "gpio-reset",
.owner = THIS_MODULE,
.of_match_table = of_match_ptr(gpio_reset_dt_ids),
},
};
static int __init gpio_reset_init(void)
{
return platform_driver_register(&gpio_reset_driver);
}
arch_initcall(gpio_reset_init);
static void __exit gpio_reset_exit(void)
{
platform_driver_unregister(&gpio_reset_driver);
}
module_exit(gpio_reset_exit);
MODULE_AUTHOR("Philipp Zabel <p.zabel@pengutronix.de>");
MODULE_DESCRIPTION("gpio reset controller");
MODULE_LICENSE("GPL");
MODULE_ALIAS("platform:gpio-reset");
MODULE_DEVICE_TABLE(of, gpio_reset_dt_ids);
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