1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  * Driver for simulating a mouse on GPIO lines.
4  *
5  * Copyright (C) 2007 Atmel Corporation
6  * Copyright (C) 2017 Linus Walleij <linus.walleij@linaro.org>
7  */
8 
9 #include <linux/module.h>
10 #include <linux/platform_device.h>
11 #include <linux/input.h>
12 #include <linux/gpio/consumer.h>
13 #include <linux/property.h>
14 #include <linux/of.h>
15 
16 /**
17  * struct gpio_mouse
18  * @scan_ms: the scan interval in milliseconds.
19  * @up: GPIO line for up value.
20  * @down: GPIO line for down value.
21  * @left: GPIO line for left value.
22  * @right: GPIO line for right value.
23  * @bleft: GPIO line for left button.
24  * @bmiddle: GPIO line for middle button.
25  * @bright: GPIO line for right button.
26  *
27  * This struct must be added to the platform_device in the board code.
28  * It is used by the gpio_mouse driver to setup GPIO lines and to
29  * calculate mouse movement.
30  */
31 struct gpio_mouse {
32 	u32 scan_ms;
33 	struct gpio_desc *up;
34 	struct gpio_desc *down;
35 	struct gpio_desc *left;
36 	struct gpio_desc *right;
37 	struct gpio_desc *bleft;
38 	struct gpio_desc *bmiddle;
39 	struct gpio_desc *bright;
40 };
41 
42 /*
43  * Timer function which is run every scan_ms ms when the device is opened.
44  * The dev input variable is set to the input_dev pointer.
45  */
gpio_mouse_scan(struct input_dev * input)46 static void gpio_mouse_scan(struct input_dev *input)
47 {
48 	struct gpio_mouse *gpio = input_get_drvdata(input);
49 	int x, y;
50 
51 	if (gpio->bleft)
52 		input_report_key(input, BTN_LEFT,
53 				 gpiod_get_value(gpio->bleft));
54 	if (gpio->bmiddle)
55 		input_report_key(input, BTN_MIDDLE,
56 				 gpiod_get_value(gpio->bmiddle));
57 	if (gpio->bright)
58 		input_report_key(input, BTN_RIGHT,
59 				 gpiod_get_value(gpio->bright));
60 
61 	x = gpiod_get_value(gpio->right) - gpiod_get_value(gpio->left);
62 	y = gpiod_get_value(gpio->down) - gpiod_get_value(gpio->up);
63 
64 	input_report_rel(input, REL_X, x);
65 	input_report_rel(input, REL_Y, y);
66 	input_sync(input);
67 }
68 
gpio_mouse_probe(struct platform_device * pdev)69 static int gpio_mouse_probe(struct platform_device *pdev)
70 {
71 	struct device *dev = &pdev->dev;
72 	struct gpio_mouse *gmouse;
73 	struct input_dev *input;
74 	int error;
75 
76 	gmouse = devm_kzalloc(dev, sizeof(*gmouse), GFP_KERNEL);
77 	if (!gmouse)
78 		return -ENOMEM;
79 
80 	/* Assign some default scanning time */
81 	error = device_property_read_u32(dev, "scan-interval-ms",
82 					 &gmouse->scan_ms);
83 	if (error || gmouse->scan_ms == 0) {
84 		dev_warn(dev, "invalid scan time, set to 50 ms\n");
85 		gmouse->scan_ms = 50;
86 	}
87 
88 	gmouse->up = devm_gpiod_get(dev, "up", GPIOD_IN);
89 	if (IS_ERR(gmouse->up))
90 		return PTR_ERR(gmouse->up);
91 	gmouse->down = devm_gpiod_get(dev, "down", GPIOD_IN);
92 	if (IS_ERR(gmouse->down))
93 		return PTR_ERR(gmouse->down);
94 	gmouse->left = devm_gpiod_get(dev, "left", GPIOD_IN);
95 	if (IS_ERR(gmouse->left))
96 		return PTR_ERR(gmouse->left);
97 	gmouse->right = devm_gpiod_get(dev, "right", GPIOD_IN);
98 	if (IS_ERR(gmouse->right))
99 		return PTR_ERR(gmouse->right);
100 
101 	gmouse->bleft = devm_gpiod_get_optional(dev, "button-left", GPIOD_IN);
102 	if (IS_ERR(gmouse->bleft))
103 		return PTR_ERR(gmouse->bleft);
104 	gmouse->bmiddle = devm_gpiod_get_optional(dev, "button-middle",
105 						  GPIOD_IN);
106 	if (IS_ERR(gmouse->bmiddle))
107 		return PTR_ERR(gmouse->bmiddle);
108 	gmouse->bright = devm_gpiod_get_optional(dev, "button-right",
109 						 GPIOD_IN);
110 	if (IS_ERR(gmouse->bright))
111 		return PTR_ERR(gmouse->bright);
112 
113 	input = devm_input_allocate_device(dev);
114 	if (!input)
115 		return -ENOMEM;
116 
117 	input->name = pdev->name;
118 	input->id.bustype = BUS_HOST;
119 
120 	input_set_drvdata(input, gmouse);
121 
122 	input_set_capability(input, EV_REL, REL_X);
123 	input_set_capability(input, EV_REL, REL_Y);
124 	if (gmouse->bleft)
125 		input_set_capability(input, EV_KEY, BTN_LEFT);
126 	if (gmouse->bmiddle)
127 		input_set_capability(input, EV_KEY, BTN_MIDDLE);
128 	if (gmouse->bright)
129 		input_set_capability(input, EV_KEY, BTN_RIGHT);
130 
131 	error = input_setup_polling(input, gpio_mouse_scan);
132 	if (error)
133 		return error;
134 
135 	input_set_poll_interval(input, gmouse->scan_ms);
136 
137 	error = input_register_device(input);
138 	if (error) {
139 		dev_err(dev, "could not register input device\n");
140 		return error;
141 	}
142 
143 	dev_dbg(dev, "%d ms scan time, buttons: %s%s%s\n",
144 		gmouse->scan_ms,
145 		gmouse->bleft ? "" : "left ",
146 		gmouse->bmiddle ? "" : "middle ",
147 		gmouse->bright ? "" : "right");
148 
149 	return 0;
150 }
151 
152 static const struct of_device_id gpio_mouse_of_match[] = {
153 	{ .compatible = "gpio-mouse", },
154 	{ },
155 };
156 MODULE_DEVICE_TABLE(of, gpio_mouse_of_match);
157 
158 static struct platform_driver gpio_mouse_device_driver = {
159 	.probe		= gpio_mouse_probe,
160 	.driver		= {
161 		.name	= "gpio_mouse",
162 		.of_match_table = gpio_mouse_of_match,
163 	}
164 };
165 module_platform_driver(gpio_mouse_device_driver);
166 
167 MODULE_AUTHOR("Hans-Christian Egtvedt <egtvedt@samfundet.no>");
168 MODULE_DESCRIPTION("GPIO mouse driver");
169 MODULE_LICENSE("GPL");
170 MODULE_ALIAS("platform:gpio_mouse"); /* work with hotplug and coldplug */
171