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