110 lines
2.7 KiB
C
110 lines
2.7 KiB
C
// 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>
|
|
|
|
#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\n",
|
|
__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", },
|
|
{},
|
|
};
|
|
MODULE_DEVICE_TABLE(of, of_gpio_poweroff_match);
|
|
|
|
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_ALIAS("platform:poweroff-gpio");
|