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9c92ab61 | 1 | // SPDX-License-Identifier: GPL-2.0-only |
371bb20d DR |
2 | /* |
3 | * Toggles a GPIO pin to restart a device | |
4 | * | |
5 | * Copyright (C) 2014 Google, Inc. | |
6 | * | |
371bb20d DR |
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); | |
b0d0d3de CP |
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; | |
371bb20d DR |
72 | } |
73 | ||
74 | gpio_restart->restart_handler.notifier_call = gpio_restart_notify; | |
bcd56fe1 | 75 | gpio_restart->restart_handler.priority = 129; |
371bb20d DR |
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", | |
371bb20d DR |
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"); |