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
  18 struct 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
  26 static 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
  51 static 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         ret = PTR_ERR_OR_ZERO(gpio_restart->reset_gpio);
  68         if (ret) {
  69                 if (ret != -EPROBE_DEFER)
  70                         dev_err(&pdev->dev, "Could not get reset GPIO\n");
  71                 return ret;
  72         }
  73
  74         gpio_restart->restart_handler.notifier_call = gpio_restart_notify;
  75         gpio_restart->restart_handler.priority = 129;
  76         gpio_restart->active_delay_ms = 100;
  77         gpio_restart->inactive_delay_ms = 100;
  78         gpio_restart->wait_delay_ms = 3000;
  79
  80         ret = of_property_read_u32(pdev->dev.of_node, "priority", &property);
  81         if (!ret) {
  82                 if (property > 255)
  83                         dev_err(&pdev->dev, "Invalid priority property: %u\n",
  84                                         property);
  85                 else
  86                         gpio_restart->restart_handler.priority = property;
  87         }
  88
  89         of_property_read_u32(pdev->dev.of_node, "active-delay",
  90                         &gpio_restart->active_delay_ms);
  91         of_property_read_u32(pdev->dev.of_node, "inactive-delay",
  92                         &gpio_restart->inactive_delay_ms);
  93         of_property_read_u32(pdev->dev.of_node, "wait-delay",
  94                         &gpio_restart->wait_delay_ms);
  95
  96         platform_set_drvdata(pdev, gpio_restart);
  97
  98         ret = register_restart_handler(&gpio_restart->restart_handler);
  99         if (ret) {
 100                 dev_err(&pdev->dev, "%s: cannot register restart handler, %d\n",
 101                                 __func__, ret);
 102                 return -ENODEV;
 103         }
 104
 105         return 0;
 106 }
 107
 108 static int gpio_restart_remove(struct platform_device *pdev)
 109 {
 110         struct gpio_restart *gpio_restart = platform_get_drvdata(pdev);
 111         int ret;
 112
 113         ret = unregister_restart_handler(&gpio_restart->restart_handler);
 114         if (ret) {
 115                 dev_err(&pdev->dev,
 116                                 "%s: cannot unregister restart handler, %d\n",
 117                                 __func__, ret);
 118                 return -ENODEV;
 119         }
 120
 121         return 0;
 122 }
 123
 124 static const struct of_device_id of_gpio_restart_match[] = {
 125         { .compatible = "gpio-restart", },
 126         {},
 127 };
 128
 129 static struct platform_driver gpio_restart_driver = {
 130         .probe = gpio_restart_probe,
 131         .remove = gpio_restart_remove,
 132         .driver = {
 133                 .name = "restart-gpio",
 134                 .of_match_table = of_gpio_restart_match,
 135         },
 136 };
 137
 138 module_platform_driver(gpio_restart_driver);
 139
 140 MODULE_AUTHOR("David Riley <davidriley@chromium.org>");
 141 MODULE_DESCRIPTION("GPIO restart driver");
 142 MODULE_LICENSE("GPL");