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