1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * Support for the S1 button on Routerboard 532
4  *
5  * Copyright (C) 2009  Phil Sutter <n0-1@freewrt.org>
6  */
7 
8 #include <linux/input-polldev.h>
9 #include <linux/module.h>
10 #include <linux/platform_device.h>
11 #include <linux/gpio.h>
12 
13 #include <asm/mach-rc32434/gpio.h>
14 #include <asm/mach-rc32434/rb.h>
15 
16 #define DRV_NAME "rb532-button"
17 
18 #define RB532_BTN_RATE 100 /* msec */
19 #define RB532_BTN_KSYM BTN_0
20 
21 /* The S1 button state is provided by GPIO pin 1. But as this
22  * pin is also used for uart input as alternate function, the
23  * operational modes must be switched first:
24  * 1) disable uart using set_latch_u5()
25  * 2) turn off alternate function implicitly through
26  *    gpio_direction_input()
27  * 3) read the GPIO's current value
28  * 4) undo step 2 by enabling alternate function (in this
29  *    mode the GPIO direction is fixed, so no change needed)
30  * 5) turn on uart again
31  * The GPIO value occurs to be inverted, so pin high means
32  * button is not pressed.
33  */
34 static bool rb532_button_pressed(void)
35 {
36 	int val;
37 
38 	set_latch_u5(0, LO_FOFF);
39 	gpio_direction_input(GPIO_BTN_S1);
40 
41 	val = gpio_get_value(GPIO_BTN_S1);
42 
43 	rb532_gpio_set_func(GPIO_BTN_S1);
44 	set_latch_u5(LO_FOFF, 0);
45 
46 	return !val;
47 }
48 
49 static void rb532_button_poll(struct input_polled_dev *poll_dev)
50 {
51 	input_report_key(poll_dev->input, RB532_BTN_KSYM,
52 			 rb532_button_pressed());
53 	input_sync(poll_dev->input);
54 }
55 
56 static int rb532_button_probe(struct platform_device *pdev)
57 {
58 	struct input_polled_dev *poll_dev;
59 	int error;
60 
61 	poll_dev = input_allocate_polled_device();
62 	if (!poll_dev)
63 		return -ENOMEM;
64 
65 	poll_dev->poll = rb532_button_poll;
66 	poll_dev->poll_interval = RB532_BTN_RATE;
67 
68 	poll_dev->input->name = "rb532 button";
69 	poll_dev->input->phys = "rb532/button0";
70 	poll_dev->input->id.bustype = BUS_HOST;
71 	poll_dev->input->dev.parent = &pdev->dev;
72 
73 	dev_set_drvdata(&pdev->dev, poll_dev);
74 
75 	input_set_capability(poll_dev->input, EV_KEY, RB532_BTN_KSYM);
76 
77 	error = input_register_polled_device(poll_dev);
78 	if (error) {
79 		input_free_polled_device(poll_dev);
80 		return error;
81 	}
82 
83 	return 0;
84 }
85 
86 static int rb532_button_remove(struct platform_device *pdev)
87 {
88 	struct input_polled_dev *poll_dev = dev_get_drvdata(&pdev->dev);
89 
90 	input_unregister_polled_device(poll_dev);
91 	input_free_polled_device(poll_dev);
92 
93 	return 0;
94 }
95 
96 static struct platform_driver rb532_button_driver = {
97 	.probe = rb532_button_probe,
98 	.remove = rb532_button_remove,
99 	.driver = {
100 		.name = DRV_NAME,
101 	},
102 };
103 module_platform_driver(rb532_button_driver);
104 
105 MODULE_AUTHOR("Phil Sutter <n0-1@freewrt.org>");
106 MODULE_LICENSE("GPL");
107 MODULE_DESCRIPTION("Support for S1 button on Routerboard 532");
108 MODULE_ALIAS("platform:" DRV_NAME);
109