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// SPDX-License-Identifier: GPL-2.0-only
/*
* 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
*/
#include <linux/kernel.h>
#include <linux/init.h>
#include <linux/delay.h>
#include <linux/platform_device.h>
#include <linux/property.h>
#include <linux/gpio/consumer.h>
#include <linux/mod_devicetable.h>
#include <linux/module.h>
#include <linux/reboot.h>
#define DEFAULT_TIMEOUT_MS 3000
struct gpio_poweroff {
struct gpio_desc *reset_gpio;
u32 timeout_ms;
u32 active_delay_ms;
u32 inactive_delay_ms;
};
static int gpio_poweroff_do_poweroff(struct sys_off_data *data)
{
struct gpio_poweroff *gpio_poweroff = data->cb_data;
/* drive it active, also inactive->active edge */
gpiod_direction_output(gpio_poweroff->reset_gpio, 1);
mdelay(gpio_poweroff->active_delay_ms);
/* drive inactive, also active->inactive edge */
gpiod_set_value_cansleep(gpio_poweroff->reset_gpio, 0);
mdelay(gpio_poweroff->inactive_delay_ms);
/* drive it active, also inactive->active edge */
gpiod_set_value_cansleep(gpio_poweroff->reset_gpio, 1);
/* give it some time */
mdelay(gpio_poweroff->timeout_ms);
/*
* If code reaches this point, it means that gpio-poweroff has failed
* to actually power off the system.
* Warn the user that the attempt to poweroff via gpio-poweroff
* has gone wrong.
*/
WARN(1, "Failed to poweroff via gpio-poweroff mechanism\n");
return NOTIFY_DONE;
}
static int gpio_poweroff_probe(struct platform_device *pdev)
{
struct gpio_poweroff *gpio_poweroff;
bool input = false;
enum gpiod_flags flags;
int priority = SYS_OFF_PRIO_DEFAULT;
bool export = false;
int ret;
gpio_poweroff = devm_kzalloc(&pdev->dev, sizeof(*gpio_poweroff), GFP_KERNEL);
if (!gpio_poweroff)
return -ENOMEM;
input = device_property_read_bool(&pdev->dev, "input");
if (input)
flags = GPIOD_IN;
else
flags = GPIOD_OUT_LOW;
gpio_poweroff->active_delay_ms = 100;
gpio_poweroff->inactive_delay_ms = 100;
gpio_poweroff->timeout_ms = DEFAULT_TIMEOUT_MS;
device_property_read_u32(&pdev->dev, "active-delay-ms", &gpio_poweroff->active_delay_ms);
device_property_read_u32(&pdev->dev, "inactive-delay-ms",
&gpio_poweroff->inactive_delay_ms);
device_property_read_u32(&pdev->dev, "timeout-ms", &gpio_poweroff->timeout_ms);
device_property_read_u32(&pdev->dev, "priority", &priority);
if (priority > 255) {
dev_err(&pdev->dev, "Invalid priority property: %u\n", priority);
return -EINVAL;
}
gpio_poweroff->reset_gpio = devm_gpiod_get(&pdev->dev, NULL, flags);
if (IS_ERR(gpio_poweroff->reset_gpio))
return PTR_ERR(gpio_poweroff->reset_gpio);
export = device_property_read_bool(&pdev->dev, "export");
if (export) {
gpiod_export(gpio_poweroff->reset_gpio, true);
gpiod_export_link(&pdev->dev, "poweroff-gpio", gpio_poweroff->reset_gpio);
}
ret = devm_register_sys_off_handler(&pdev->dev, SYS_OFF_MODE_POWER_OFF,
priority, gpio_poweroff_do_poweroff, gpio_poweroff);
if (ret) {
gpiod_unexport(gpio_poweroff->reset_gpio);
return dev_err_probe(&pdev->dev, ret, "Cannot register poweroff handler\n");
}
return 0;
}
static const struct of_device_id of_gpio_poweroff_match[] = {
{ .compatible = "gpio-poweroff", },
{},
};
MODULE_DEVICE_TABLE(of, of_gpio_poweroff_match);
static struct platform_driver gpio_poweroff_driver = {
.probe = gpio_poweroff_probe,
.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_ALIAS("platform:poweroff-gpio");
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