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/*
* Toggles a GPIO pin to restart a device
*
* Copyright (C) 2014 Google, Inc.
*
* This software is licensed under the terms of the GNU General Public
* License version 2, as published by the Free Software Foundation, and
* may be copied, distributed, and modified under those terms.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* Based on the gpio-poweroff driver.
*/
#include <linux/reboot.h>
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/delay.h>
#include <linux/platform_device.h>
#include <linux/gpio/consumer.h>
#include <linux/of_platform.h>
#include <linux/module.h>
struct gpio_restart {
struct gpio_desc *reset_gpio;
struct notifier_block restart_handler;
u32 active_delay_ms;
u32 inactive_delay_ms;
u32 wait_delay_ms;
};
static int gpio_restart_notify(struct notifier_block *this,
unsigned long mode, void *cmd)
{
struct gpio_restart *gpio_restart =
container_of(this, struct gpio_restart, restart_handler);
/* drive it active, also inactive->active edge */
gpiod_direction_output(gpio_restart->reset_gpio, 1);
mdelay(gpio_restart->active_delay_ms);
/* drive inactive, also active->inactive edge */
gpiod_set_value(gpio_restart->reset_gpio, 0);
mdelay(gpio_restart->inactive_delay_ms);
/* drive it active, also inactive->active edge */
gpiod_set_value(gpio_restart->reset_gpio, 1);
/* give it some time */
mdelay(gpio_restart->wait_delay_ms);
WARN_ON(1);
return NOTIFY_DONE;
}
static int gpio_restart_probe(struct platform_device *pdev)
{
struct gpio_restart *gpio_restart;
bool open_source = false;
u32 property;
int ret;
gpio_restart = devm_kzalloc(&pdev->dev, sizeof(*gpio_restart),
GFP_KERNEL);
if (!gpio_restart)
return -ENOMEM;
open_source = of_property_read_bool(pdev->dev.of_node, "open-source");
gpio_restart->reset_gpio = devm_gpiod_get(&pdev->dev, NULL,
open_source ? GPIOD_IN : GPIOD_OUT_LOW);
if (IS_ERR(gpio_restart->reset_gpio)) {
dev_err(&pdev->dev, "Could net get reset GPIO\n");
return PTR_ERR(gpio_restart->reset_gpio);
}
gpio_restart->restart_handler.notifier_call = gpio_restart_notify;
gpio_restart->restart_handler.priority = 129;
gpio_restart->active_delay_ms = 100;
gpio_restart->inactive_delay_ms = 100;
gpio_restart->wait_delay_ms = 3000;
ret = of_property_read_u32(pdev->dev.of_node, "priority", &property);
if (!ret) {
if (property > 255)
dev_err(&pdev->dev, "Invalid priority property: %u\n",
property);
else
gpio_restart->restart_handler.priority = property;
}
of_property_read_u32(pdev->dev.of_node, "active-delay",
&gpio_restart->active_delay_ms);
of_property_read_u32(pdev->dev.of_node, "inactive-delay",
&gpio_restart->inactive_delay_ms);
of_property_read_u32(pdev->dev.of_node, "wait-delay",
&gpio_restart->wait_delay_ms);
platform_set_drvdata(pdev, gpio_restart);
ret = register_restart_handler(&gpio_restart->restart_handler);
if (ret) {
dev_err(&pdev->dev, "%s: cannot register restart handler, %d\n",
__func__, ret);
return -ENODEV;
}
return 0;
}
static int gpio_restart_remove(struct platform_device *pdev)
{
struct gpio_restart *gpio_restart = platform_get_drvdata(pdev);
int ret;
ret = unregister_restart_handler(&gpio_restart->restart_handler);
if (ret) {
dev_err(&pdev->dev,
"%s: cannot unregister restart handler, %d\n",
__func__, ret);
return -ENODEV;
}
return 0;
}
static const struct of_device_id of_gpio_restart_match[] = {
{ .compatible = "gpio-restart", },
{},
};
static struct platform_driver gpio_restart_driver = {
.probe = gpio_restart_probe,
.remove = gpio_restart_remove,
.driver = {
.name = "restart-gpio",
.of_match_table = of_gpio_restart_match,
},
};
module_platform_driver(gpio_restart_driver);
MODULE_AUTHOR("David Riley <davidriley@chromium.org>");
MODULE_DESCRIPTION("GPIO restart driver");
MODULE_LICENSE("GPL");
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