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.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_dev *input)
50 {
51 	input_report_key(input, RB532_BTN_KSYM, rb532_button_pressed());
52 	input_sync(input);
53 }
54 
55 static int rb532_button_probe(struct platform_device *pdev)
56 {
57 	struct input_dev *input;
58 	int error;
59 
60 	input = devm_input_allocate_device(&pdev->dev);
61 	if (!input)
62 		return -ENOMEM;
63 
64 	input->name = "rb532 button";
65 	input->phys = "rb532/button0";
66 	input->id.bustype = BUS_HOST;
67 
68 	input_set_capability(input, EV_KEY, RB532_BTN_KSYM);
69 
70 	error = input_setup_polling(input, rb532_button_poll);
71 	if (error)
72 		return error;
73 
74 	input_set_poll_interval(input, RB532_BTN_RATE);
75 
76 	error = input_register_device(input);
77 	if (error)
78 		return error;
79 
80 	return 0;
81 }
82 
83 static struct platform_driver rb532_button_driver = {
84 	.probe = rb532_button_probe,
85 	.driver = {
86 		.name = DRV_NAME,
87 	},
88 };
89 module_platform_driver(rb532_button_driver);
90 
91 MODULE_AUTHOR("Phil Sutter <n0-1@freewrt.org>");
92 MODULE_LICENSE("GPL");
93 MODULE_DESCRIPTION("Support for S1 button on Routerboard 532");
94 MODULE_ALIAS("platform:" DRV_NAME);
95