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/*
* Toggles a GPIO pin to power down a device
*
* Jamie Lentin <jm@lentin.co.uk>
* Andrew Lunn <andrew@lunn.ch>
*
* Copyright (C) 2012 Jamie Lentin
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License version 2 as
* published by the Free Software Foundation.
*
*/
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/delay.h>
#include <linux/platform_device.h>
#include <linux/gpio.h>
#include <linux/of_platform.h>
#include <linux/of_gpio.h>
#include <linux/module.h>
/*
* Hold configuration here, cannot be more than one instance of the driver
* since pm_power_off itself is global.
*/
static int gpio_num = -1;
static int gpio_active_low;
static void gpio_poweroff_do_poweroff(void)
{
BUG_ON(gpio_num == -1);
/* drive it active */
gpio_direction_output(gpio_num, !gpio_active_low);
mdelay(100);
/* rising edge or drive inactive */
gpio_set_value(gpio_num, gpio_active_low);
mdelay(100);
/* falling edge */
gpio_set_value(gpio_num, !gpio_active_low);
/* give it some time */
mdelay(3000);
WARN_ON(1);
}
static int gpio_poweroff_probe(struct platform_device *pdev)
{
enum of_gpio_flags flags;
bool input = false;
int ret;
/* If a pm_power_off function has already been added, leave it alone */
if (pm_power_off != NULL) {
pr_err("%s: pm_power_off function already registered",
__func__);
return -EBUSY;
}
gpio_num = of_get_gpio_flags(pdev->dev.of_node, 0, &flags);
if (gpio_num < 0) {
pr_err("%s: Could not get GPIO configuration: %d",
__func__, gpio_num);
return -ENODEV;
}
gpio_active_low = flags & OF_GPIO_ACTIVE_LOW;
if (of_get_property(pdev->dev.of_node, "input", NULL))
input = true;
ret = gpio_request(gpio_num, "poweroff-gpio");
if (ret) {
pr_err("%s: Could not get GPIO %d", __func__, gpio_num);
return ret;
}
if (input) {
if (gpio_direction_input(gpio_num)) {
pr_err("Could not set direction of GPIO %d to input",
gpio_num);
goto err;
}
} else {
if (gpio_direction_output(gpio_num, gpio_active_low)) {
pr_err("Could not set direction of GPIO %d", gpio_num);
goto err;
}
}
pm_power_off = &gpio_poweroff_do_poweroff;
return 0;
err:
gpio_free(gpio_num);
return -ENODEV;
}
static int gpio_poweroff_remove(struct platform_device *pdev)
{
if (gpio_num != -1)
gpio_free(gpio_num);
if (pm_power_off == &gpio_poweroff_do_poweroff)
pm_power_off = NULL;
return 0;
}
static const struct of_device_id of_gpio_poweroff_match[] = {
{ .compatible = "gpio-poweroff", },
{},
};
static struct platform_driver gpio_poweroff_driver = {
.probe = gpio_poweroff_probe,
.remove = gpio_poweroff_remove,
.driver = {
.name = "poweroff-gpio",
.owner = THIS_MODULE,
.of_match_table = of_gpio_poweroff_match,
},
};
module_platform_driver(gpio_poweroff_driver);
MODULE_AUTHOR("Jamie Lentin <jm@lentin.co.uk>");
MODULE_DESCRIPTION("GPIO poweroff driver");
MODULE_LICENSE("GPL");
MODULE_ALIAS("platform:poweroff-gpio");
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