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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#define DEFAULT_TIMEOUT_MS 3000
19
20
21
22
23static struct gpio_desc *reset_gpio;
24static u32 timeout = DEFAULT_TIMEOUT_MS;
25static u32 active_delay = 100;
26static u32 inactive_delay = 100;
27
28static void gpio_poweroff_do_poweroff(void)
29{
30 BUG_ON(!reset_gpio);
31
32
33 gpiod_direction_output(reset_gpio, 1);
34 mdelay(active_delay);
35
36
37 gpiod_set_value_cansleep(reset_gpio, 0);
38 mdelay(inactive_delay);
39
40
41 gpiod_set_value_cansleep(reset_gpio, 1);
42
43
44 mdelay(timeout);
45
46 WARN_ON(1);
47}
48
49static int gpio_poweroff_probe(struct platform_device *pdev)
50{
51 bool input = false;
52 enum gpiod_flags flags;
53
54
55 if (pm_power_off != NULL) {
56 dev_err(&pdev->dev,
57 "%s: pm_power_off function already registered\n",
58 __func__);
59 return -EBUSY;
60 }
61
62 input = device_property_read_bool(&pdev->dev, "input");
63 if (input)
64 flags = GPIOD_IN;
65 else
66 flags = GPIOD_OUT_LOW;
67
68 device_property_read_u32(&pdev->dev, "active-delay-ms", &active_delay);
69 device_property_read_u32(&pdev->dev, "inactive-delay-ms",
70 &inactive_delay);
71 device_property_read_u32(&pdev->dev, "timeout-ms", &timeout);
72
73 reset_gpio = devm_gpiod_get(&pdev->dev, NULL, flags);
74 if (IS_ERR(reset_gpio))
75 return PTR_ERR(reset_gpio);
76
77 pm_power_off = &gpio_poweroff_do_poweroff;
78 return 0;
79}
80
81static int gpio_poweroff_remove(struct platform_device *pdev)
82{
83 if (pm_power_off == &gpio_poweroff_do_poweroff)
84 pm_power_off = NULL;
85
86 return 0;
87}
88
89static const struct of_device_id of_gpio_poweroff_match[] = {
90 { .compatible = "gpio-poweroff", },
91 {},
92};
93MODULE_DEVICE_TABLE(of, of_gpio_poweroff_match);
94
95static struct platform_driver gpio_poweroff_driver = {
96 .probe = gpio_poweroff_probe,
97 .remove = gpio_poweroff_remove,
98 .driver = {
99 .name = "poweroff-gpio",
100 .of_match_table = of_gpio_poweroff_match,
101 },
102};
103
104module_platform_driver(gpio_poweroff_driver);
105
106MODULE_AUTHOR("Jamie Lentin <jm@lentin.co.uk>");
107MODULE_DESCRIPTION("GPIO poweroff driver");
108MODULE_LICENSE("GPL v2");
109MODULE_ALIAS("platform:poweroff-gpio");
110