113 lines
2.6 KiB
C
113 lines
2.6 KiB
C
|
/*
|
||
|
|
* 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>
|
||
|
|
|
||
|
|
/*
|
||
|
|
* 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 void gpio_poweroff_do_poweroff(void)
|
||
|
|
{
|
||
|
|
BUG_ON(!reset_gpio);
|
||
|
|
|
||
|
|
/* drive it active, also inactive->active edge */
|
||
|
|
gpiod_direction_output(reset_gpio, 1);
|
||
|
|
mdelay(100);
|
||
|
|
/* drive inactive, also active->inactive edge */
|
||
|
|
gpiod_set_value(reset_gpio, 0);
|
||
|
|
mdelay(100);
|
||
|
|
|
||
|
|
/* drive it active, also inactive->active edge */
|
||
|
|
gpiod_set_value(reset_gpio, 1);
|
||
|
|
|
||
|
|
/* give it some time */
|
||
|
|
mdelay(3000);
|
||
|
|
|
||
|
|
WARN_ON(1);
|
||
|
|
}
|
||
|
|
|
||
|
|
static int gpio_poweroff_probe(struct platform_device *pdev)
|
||
|
|
{
|
||
|
|
bool input = false;
|
||
|
|
|
||
|
|
/* 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;
|
||
|
|
}
|
||
|
|
|
||
|
|
reset_gpio = devm_gpiod_get(&pdev->dev, NULL);
|
||
|
|
if (IS_ERR(reset_gpio))
|
||
|
|
return PTR_ERR(reset_gpio);
|
||
|
|
|
||
|
|
input = of_property_read_bool(pdev->dev.of_node, "input");
|
||
|
|
|
||
|
|
if (input) {
|
||
|
|
if (gpiod_direction_input(reset_gpio)) {
|
||
|
|
dev_err(&pdev->dev,
|
||
|
|
"Could not set direction of reset GPIO to input\n");
|
||
|
|
return -ENODEV;
|
||
|
|
}
|
||
|
|
} else {
|
||
|
|
if (gpiod_direction_output(reset_gpio, 0)) {
|
||
|
|
dev_err(&pdev->dev,
|
||
|
|
"Could not set direction of reset GPIO\n");
|
||
|
|
return -ENODEV;
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
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",
|
||
|
|
.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 v2");
|
||
|
|
MODULE_ALIAS("platform:poweroff-gpio");
|