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 */
rb532_button_pressed(void)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
rb532_button_poll(struct input_dev * input)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
rb532_button_probe(struct platform_device * pdev)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