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 */
34static 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
49static 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
55static 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
83static struct platform_driver rb532_button_driver = {
84	.probe = rb532_button_probe,
85	.driver = {
86		.name = DRV_NAME,
87	},
88};
89module_platform_driver(rb532_button_driver);
90
91MODULE_AUTHOR("Phil Sutter <n0-1@freewrt.org>");
92MODULE_LICENSE("GPL");
93MODULE_DESCRIPTION("Support for S1 button on Routerboard 532");
94MODULE_ALIAS("platform:" DRV_NAME);
95