1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3  * Raspberry Pi Sense HAT joystick driver
4  * http://raspberrypi.org
5  *
6  * Copyright (C) 2015 Raspberry Pi
7  * Copyright (C) 2021 Charles Mirabile, Mwesigwa Guma, Joel Savitz
8  *
9  * Original Author: Serge Schneider
10  * Revised for upstream Linux by: Charles Mirabile, Mwesigwa Guma, Joel Savitz
11  */
12 
13 #include <linux/module.h>
14 #include <linux/input.h>
15 #include <linux/i2c.h>
16 #include <linux/interrupt.h>
17 #include <linux/platform_device.h>
18 #include <linux/regmap.h>
19 #include <linux/property.h>
20 
21 #define JOYSTICK_SMB_REG 0xf2
22 
23 struct sensehat_joystick {
24 	struct platform_device *pdev;
25 	struct input_dev *keys_dev;
26 	unsigned long prev_states;
27 	struct regmap *regmap;
28 };
29 
30 static const unsigned int keymap[] = {
31 	BTN_DPAD_DOWN, BTN_DPAD_RIGHT, BTN_DPAD_UP, BTN_SELECT, BTN_DPAD_LEFT,
32 };
33 
34 static irqreturn_t sensehat_joystick_report(int irq, void *cookie)
35 {
36 	struct sensehat_joystick *sensehat_joystick = cookie;
37 	unsigned long curr_states, changes;
38 	unsigned int keys;
39 	int error;
40 	int i;
41 
42 	error = regmap_read(sensehat_joystick->regmap, JOYSTICK_SMB_REG, &keys);
43 	if (error < 0) {
44 		dev_err(&sensehat_joystick->pdev->dev,
45 			"Failed to read joystick state: %d", error);
46 		return IRQ_NONE;
47 	}
48 	curr_states = keys;
49 	bitmap_xor(&changes, &curr_states, &sensehat_joystick->prev_states,
50 		   ARRAY_SIZE(keymap));
51 
52 	for_each_set_bit(i, &changes, ARRAY_SIZE(keymap))
53 		input_report_key(sensehat_joystick->keys_dev, keymap[i],
54 				 curr_states & BIT(i));
55 
56 	input_sync(sensehat_joystick->keys_dev);
57 	sensehat_joystick->prev_states = keys;
58 	return IRQ_HANDLED;
59 }
60 
61 static int sensehat_joystick_probe(struct platform_device *pdev)
62 {
63 	struct sensehat_joystick *sensehat_joystick;
64 	int error, i, irq;
65 
66 	sensehat_joystick = devm_kzalloc(&pdev->dev, sizeof(*sensehat_joystick),
67 					 GFP_KERNEL);
68 	if (!sensehat_joystick)
69 		return -ENOMEM;
70 
71 	sensehat_joystick->pdev = pdev;
72 
73 	sensehat_joystick->regmap = dev_get_regmap(pdev->dev.parent, NULL);
74 	if (!sensehat_joystick->regmap) {
75 		dev_err(&pdev->dev, "unable to get sensehat regmap");
76 		return -ENODEV;
77 	}
78 
79 	sensehat_joystick->keys_dev = devm_input_allocate_device(&pdev->dev);
80 	if (!sensehat_joystick->keys_dev) {
81 		dev_err(&pdev->dev, "Could not allocate input device");
82 		return -ENOMEM;
83 	}
84 
85 	sensehat_joystick->keys_dev->name = "Raspberry Pi Sense HAT Joystick";
86 	sensehat_joystick->keys_dev->phys = "sensehat-joystick/input0";
87 	sensehat_joystick->keys_dev->id.bustype = BUS_I2C;
88 
89 	__set_bit(EV_KEY, sensehat_joystick->keys_dev->evbit);
90 	__set_bit(EV_REP, sensehat_joystick->keys_dev->evbit);
91 	for (i = 0; i < ARRAY_SIZE(keymap); i++)
92 		__set_bit(keymap[i], sensehat_joystick->keys_dev->keybit);
93 
94 	error = input_register_device(sensehat_joystick->keys_dev);
95 	if (error) {
96 		dev_err(&pdev->dev, "Could not register input device");
97 		return error;
98 	}
99 
100 	irq = platform_get_irq(pdev, 0);
101 	if (irq < 0) {
102 		dev_err(&pdev->dev, "Could not retrieve interrupt request");
103 		return irq;
104 	}
105 
106 	error = devm_request_threaded_irq(&pdev->dev, irq,
107 					  NULL, sensehat_joystick_report,
108 					  IRQF_ONESHOT, "keys",
109 					  sensehat_joystick);
110 	if (error) {
111 		dev_err(&pdev->dev, "IRQ request failed");
112 		return error;
113 	}
114 
115 	return 0;
116 }
117 
118 static const struct of_device_id sensehat_joystick_device_id[] = {
119 	{ .compatible = "raspberrypi,sensehat-joystick" },
120 	{},
121 };
122 MODULE_DEVICE_TABLE(of, sensehat_joystick_device_id);
123 
124 static struct platform_driver sensehat_joystick_driver = {
125 	.probe = sensehat_joystick_probe,
126 	.driver = {
127 		.name = "sensehat-joystick",
128 		.of_match_table = sensehat_joystick_device_id,
129 	},
130 };
131 
132 module_platform_driver(sensehat_joystick_driver);
133 
134 MODULE_DESCRIPTION("Raspberry Pi Sense HAT joystick driver");
135 MODULE_AUTHOR("Charles Mirabile <cmirabil@redhat.com>");
136 MODULE_AUTHOR("Serge Schneider <serge@raspberrypi.org>");
137 MODULE_LICENSE("GPL");
138