LXR linux/drivers/power/reset/gpio-restart.c

   1// SPDX-License-Identifier: GPL-2.0-only
   2/*
   3 * Toggles a GPIO pin to restart a device
   4 *
   5 * Copyright (C) 2014 Google, Inc.
   6 *
   7 * Based on the gpio-poweroff driver.
   8 */
   9#include <linux/reboot.h>
  10#include <linux/kernel.h>
  11#include <linux/init.h>
  12#include <linux/delay.h>
  13#include <linux/platform_device.h>
  14#include <linux/gpio/consumer.h>
  15#include <linux/of_platform.h>
  16#include <linux/module.h>
  17
  18struct gpio_restart {
  19        struct gpio_desc *reset_gpio;
  20        struct notifier_block restart_handler;
  21        u32 active_delay_ms;
  22        u32 inactive_delay_ms;
  23        u32 wait_delay_ms;
  24};
  25
  26static int gpio_restart_notify(struct notifier_block *this,
  27                                unsigned long mode, void *cmd)
  28{
  29        struct gpio_restart *gpio_restart =
  30                container_of(this, struct gpio_restart, restart_handler);
  31
  32        /* drive it active, also inactive->active edge */
  33        gpiod_direction_output(gpio_restart->reset_gpio, 1);
  34        mdelay(gpio_restart->active_delay_ms);
  35
  36        /* drive inactive, also active->inactive edge */
  37        gpiod_set_value(gpio_restart->reset_gpio, 0);
  38        mdelay(gpio_restart->inactive_delay_ms);
  39
  40        /* drive it active, also inactive->active edge */
  41        gpiod_set_value(gpio_restart->reset_gpio, 1);
  42
  43        /* give it some time */
  44        mdelay(gpio_restart->wait_delay_ms);
  45
  46        WARN_ON(1);
  47
  48        return NOTIFY_DONE;
  49}
  50
  51static int gpio_restart_probe(struct platform_device *pdev)
  52{
  53        struct gpio_restart *gpio_restart;
  54        bool open_source = false;
  55        u32 property;
  56        int ret;
  57
  58        gpio_restart = devm_kzalloc(&pdev->dev, sizeof(*gpio_restart),
  59                        GFP_KERNEL);
  60        if (!gpio_restart)
  61                return -ENOMEM;
  62
  63        open_source = of_property_read_bool(pdev->dev.of_node, "open-source");
  64
  65        gpio_restart->reset_gpio = devm_gpiod_get(&pdev->dev, NULL,
  66                        open_source ? GPIOD_IN : GPIOD_OUT_LOW);
  67        if (IS_ERR(gpio_restart->reset_gpio)) {
  68                dev_err(&pdev->dev, "Could net get reset GPIO\n");
  69                return PTR_ERR(gpio_restart->reset_gpio);
  70        }
  71
  72        gpio_restart->restart_handler.notifier_call = gpio_restart_notify;
  73        gpio_restart->restart_handler.priority = 129;
  74        gpio_restart->active_delay_ms = 100;
  75        gpio_restart->inactive_delay_ms = 100;
  76        gpio_restart->wait_delay_ms = 3000;
  77
  78        ret = of_property_read_u32(pdev->dev.of_node, "priority", &property);
  79        if (!ret) {
  80                if (property > 255)
  81                        dev_err(&pdev->dev, "Invalid priority property: %u\n",
  82                                        property);
  83                else
  84                        gpio_restart->restart_handler.priority = property;
  85        }
  86
  87        of_property_read_u32(pdev->dev.of_node, "active-delay",
  88                        &gpio_restart->active_delay_ms);
  89        of_property_read_u32(pdev->dev.of_node, "inactive-delay",
  90                        &gpio_restart->inactive_delay_ms);
  91        of_property_read_u32(pdev->dev.of_node, "wait-delay",
  92                        &gpio_restart->wait_delay_ms);
  93
  94        platform_set_drvdata(pdev, gpio_restart);
  95
  96        ret = register_restart_handler(&gpio_restart->restart_handler);
  97        if (ret) {
  98                dev_err(&pdev->dev, "%s: cannot register restart handler, %d\n",
  99                                __func__, ret);
 100                return -ENODEV;
 101        }
 102
 103        return 0;
 104}
 105
 106static int gpio_restart_remove(struct platform_device *pdev)
 107{
 108        struct gpio_restart *gpio_restart = platform_get_drvdata(pdev);
 109        int ret;
 110
 111        ret = unregister_restart_handler(&gpio_restart->restart_handler);
 112        if (ret) {
 113                dev_err(&pdev->dev,
 114                                "%s: cannot unregister restart handler, %d\n",
 115                                __func__, ret);
 116                return -ENODEV;
 117        }
 118
 119        return 0;
 120}
 121
 122static const struct of_device_id of_gpio_restart_match[] = {
 123        { .compatible = "gpio-restart", },
 124        {},
 125};
 126
 127static struct platform_driver gpio_restart_driver = {
 128        .probe = gpio_restart_probe,
 129        .remove = gpio_restart_remove,
 130        .driver = {
 131                .name = "restart-gpio",
 132                .of_match_table = of_gpio_restart_match,
 133        },
 134};
 135
 136module_platform_driver(gpio_restart_driver);
 137
 138MODULE_AUTHOR("David Riley <davidriley@chromium.org>");
 139MODULE_DESCRIPTION("GPIO restart driver");
 140MODULE_LICENSE("GPL");
 141