linux-imx

/*

 * Toggles a GPIO pin to restart a device

 *

 * Copyright (C) 2014 Google, Inc.

 *

 * This software is licensed under the terms of the GNU General Public

 * License version 2, as published by the Free Software Foundation, and

 * may be copied, distributed, and modified under those terms.

 *

 * This program is distributed in the hope that it will be useful,

 * but WITHOUT ANY WARRANTY; without even the implied warranty of

 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

 * GNU General Public License for more details.

 *

 * Based on the gpio-poweroff driver.

 */

#include <linux/reboot.h>

#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>

​

struct gpio_restart {

    struct gpio_desc *reset_gpio;

    struct notifier_block restart_handler;

    u32 active_delay_ms;

    u32 inactive_delay_ms;

    u32 wait_delay_ms;

};

​

static int gpio_restart_notify(struct notifier_block *this,

                unsigned long mode, void *cmd)

{

    struct gpio_restart *gpio_restart =

        container_of(this, struct gpio_restart, restart_handler);

​

    /* drive it active, also inactive->active edge */

    gpiod_direction_output(gpio_restart->reset_gpio, 1);

    mdelay(gpio_restart->active_delay_ms);

​

    /* drive inactive, also active->inactive edge */

    gpiod_set_value(gpio_restart->reset_gpio, 0);

    mdelay(gpio_restart->inactive_delay_ms);

​

    /* drive it active, also inactive->active edge */

    gpiod_set_value(gpio_restart->reset_gpio, 1);

​

    /* give it some time */

    mdelay(gpio_restart->wait_delay_ms);

​

    WARN_ON(1);

​

    return NOTIFY_DONE;

}

​

static int gpio_restart_probe(struct platform_device *pdev)

{

    struct gpio_restart *gpio_restart;

    bool open_source = false;

    u32 property;