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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/consumer.h>
#include <linux/of_platform.h>
#include <linux/module.h>
#define DEFAULT_TIMEOUT_MS 3000
/*
* Hold configuration here, cannot be more than one instance of the driver
* since pm_power_off itself is global.
*/
static struct gpio_desc *reset_gpio;
static u32 timeout = DEFAULT_TIMEOUT_MS;
static u32 active_delay = 100;
static u32 inactive_delay = 100;
static void gpio_poweroff_do_poweroff(void)
{
BUG_ON(!reset_gpio);
/* drive it active, also inactive->active edge */
gpiod_direction_output(reset_gpio, 1);
mdelay(active_delay);
/* drive inactive, also active->inactive edge */
gpiod_set_value_cansleep(reset_gpio, 0);
mdelay(inactive_delay);
/* drive it active, also inactive->active edge */
gpiod_set_value_cansleep(reset_gpio, 1);
/* give it some time */
mdelay(timeout);
WARN_ON(1);
}
static int gpio_poweroff_probe(struct platform_device *pdev)
{
bool input = false;
enum gpiod_flags flags;
/* If a pm_power_off function has already been added, leave it alone */
if (pm_power_off != NULL) {
dev_err(&pdev->dev,
"%s: pm_power_off function already registered",
__func__);
return -EBUSY;
}
input = device_property_read_bool(&pdev->dev, "input");
if (input)
flags = GPIOD_IN;
else
flags = GPIOD_OUT_LOW;
device_property_read_u32(&pdev->dev, "active-delay-ms", &active_delay);
device_property_read_u32(&pdev->dev, "inactive-delay-ms",
&inactive_delay);
device_property_read_u32(&pdev->dev, "timeout-ms", &timeout);
reset_gpio = devm_gpiod_get(&pdev->dev, NULL, flags);
if (IS_ERR(reset_gpio))
return PTR_ERR(reset_gpio);
pm_power_off = &gpio_poweroff_do_poweroff;
return 0;
}
static int gpio_poweroff_remove(struct platform_device *pdev)
{
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",
.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 v2");
MODULE_ALIAS("platform:poweroff-gpio");
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