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/module.h>
  16 #include <linux/of.h>
  17
  18 struct gpio_restart {
  19         struct gpio_desc *reset_gpio;
  20         u32 active_delay_ms;
  21         u32 inactive_delay_ms;
  22         u32 wait_delay_ms;
  23 };
  24
  25 static int gpio_restart_notify(struct sys_off_data *data)
  26 {
  27         struct gpio_restart *gpio_restart = data->cb_data;
  28
  29         /* drive it active, also inactive->active edge */
  30         gpiod_direction_output(gpio_restart->reset_gpio, 1);
  31         mdelay(gpio_restart->active_delay_ms);
  32
  33         /* drive inactive, also active->inactive edge */
  34         gpiod_set_value(gpio_restart->reset_gpio, 0);
  35         mdelay(gpio_restart->inactive_delay_ms);
  36
  37         /* drive it active, also inactive->active edge */
  38         gpiod_set_value(gpio_restart->reset_gpio, 1);
  39
  40         /* give it some time */
  41         mdelay(gpio_restart->wait_delay_ms);
  42
  43         WARN_ON(1);
  44
  45         return NOTIFY_DONE;
  46 }
  47
  48 static int gpio_restart_probe(struct platform_device *pdev)
  49 {
  50         struct gpio_restart *gpio_restart;
  51         bool open_source = false;
  52         int priority = 129;
  53         u32 property;
  54         int ret;
  55
  56         gpio_restart = devm_kzalloc(&pdev->dev, sizeof(*gpio_restart),
  57                         GFP_KERNEL);
  58         if (!gpio_restart)
  59                 return -ENOMEM;
  60
  61         open_source = of_property_read_bool(pdev->dev.of_node, "open-source");
  62
  63         gpio_restart->reset_gpio = devm_gpiod_get(&pdev->dev, NULL,
  64                         open_source ? GPIOD_IN : GPIOD_OUT_LOW);
  65         ret = PTR_ERR_OR_ZERO(gpio_restart->reset_gpio);
  66         if (ret) {
  67                 if (ret != -EPROBE_DEFER)
  68                         dev_err(&pdev->dev, "Could not get reset GPIO\n");
  69                 return ret;
  70         }
  71
  72         gpio_restart->active_delay_ms = 100;
  73         gpio_restart->inactive_delay_ms = 100;
  74         gpio_restart->wait_delay_ms = 3000;
  75
  76         ret = of_property_read_u32(pdev->dev.of_node, "priority", &property);
  77         if (!ret) {
  78                 if (property > 255)
  79                         dev_err(&pdev->dev, "Invalid priority property: %u\n",
  80                                         property);
  81                 else
  82                         priority = property;
  83         }
  84
  85         of_property_read_u32(pdev->dev.of_node, "active-delay",
  86                         &gpio_restart->active_delay_ms);
  87         of_property_read_u32(pdev->dev.of_node, "inactive-delay",
  88                         &gpio_restart->inactive_delay_ms);
  89         of_property_read_u32(pdev->dev.of_node, "wait-delay",
  90                         &gpio_restart->wait_delay_ms);
  91
  92         ret = devm_register_sys_off_handler(&pdev->dev,
  93                                             SYS_OFF_MODE_RESTART,
  94                                             priority,
  95                                             gpio_restart_notify,
  96                                             gpio_restart);
  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
 106 static const struct of_device_id of_gpio_restart_match[] = {
 107         { .compatible = "gpio-restart", },
 108         {},
 109 };
 110
 111 static struct platform_driver gpio_restart_driver = {
 112         .probe = gpio_restart_probe,
 113         .driver = {
 114                 .name = "restart-gpio",
 115                 .of_match_table = of_gpio_restart_match,
 116         },
 117 };
 118
 119 module_platform_driver(gpio_restart_driver);
 120
 121 MODULE_AUTHOR("David Riley <davidriley@chromium.org>");
 122 MODULE_DESCRIPTION("GPIO restart driver");