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
gpio_restart_notify(struct sys_off_data * data)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
gpio_restart_probe(struct platform_device * pdev)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");
123