1// SPDX-License-Identifier: GPL-2.0-or-later
2/*
3 *  Copyright (c) 2001 Arndt Schoenewald
4 *  Copyright (c) 2000-2001 Vojtech Pavlik
5 *  Copyright (c) 2000 Mark Fletcher
6 *
7 *  Sponsored by Quelltext AG (http://www.quelltext-ag.de), Dortmund, Germany
8 */
9
10/*
11 * Driver to use Handykey's Twiddler (the first edition, i.e. the one with
12 * the RS232 interface) as a joystick under Linux
13 *
14 * The Twiddler is a one-handed chording keyboard featuring twelve buttons on
15 * the front, six buttons on the top, and a built-in tilt sensor. The buttons
16 * on the front, which are grouped as four rows of three buttons, are pressed
17 * by the four fingers (this implies only one button per row can be held down
18 * at the same time) and the buttons on the top are for the thumb. The tilt
19 * sensor delivers X and Y axis data depending on how the Twiddler is held.
20 * Additional information can be found at http://www.handykey.com.
21 *
22 * This driver does not use the Twiddler for its intended purpose, i.e. as
23 * a chording keyboard, but as a joystick: pressing and releasing a button
24 * immediately sends a corresponding button event, and tilting it generates
25 * corresponding ABS_X and ABS_Y events. This turns the Twiddler into a game
26 * controller with amazing 18 buttons :-)
27 *
28 * Note: The Twiddler2 (the successor of the Twiddler that connects directly
29 * to the PS/2 keyboard and mouse ports) is NOT supported by this driver!
30 *
31 * For questions or feedback regarding this driver module please contact:
32 * Arndt Schoenewald <arndt@quelltext.com>
33 */
34
35/*
36 */
37
38#include <linux/kernel.h>
39#include <linux/module.h>
40#include <linux/slab.h>
41#include <linux/input.h>
42#include <linux/serio.h>
43
44#define DRIVER_DESC	"Handykey Twiddler keyboard as a joystick driver"
45
46MODULE_DESCRIPTION(DRIVER_DESC);
47MODULE_LICENSE("GPL");
48
49/*
50 * Constants.
51 */
52
53#define TWIDJOY_MAX_LENGTH 5
54
55static struct twidjoy_button_spec {
56	int bitshift;
57	int bitmask;
58	int buttons[3];
59}
60twidjoy_buttons[] = {
61	{  0, 3, { BTN_A,      BTN_B,     BTN_C    } },
62	{  2, 3, { BTN_X,      BTN_Y,     BTN_Z    } },
63	{  4, 3, { BTN_TL,     BTN_TR,    BTN_TR2  } },
64	{  6, 3, { BTN_SELECT, BTN_START, BTN_MODE } },
65	{  8, 1, { BTN_BASE5                       } },
66	{  9, 1, { BTN_BASE                        } },
67	{ 10, 1, { BTN_BASE3                       } },
68	{ 11, 1, { BTN_BASE4                       } },
69	{ 12, 1, { BTN_BASE2                       } },
70	{ 13, 1, { BTN_BASE6                       } },
71	{ 0,  0, { 0                               } }
72};
73
74/*
75 * Per-Twiddler data.
76 */
77
78struct twidjoy {
79	struct input_dev *dev;
80	int idx;
81	unsigned char data[TWIDJOY_MAX_LENGTH];
82	char phys[32];
83};
84
85/*
86 * twidjoy_process_packet() decodes packets the driver receives from the
87 * Twiddler. It updates the data accordingly.
88 */
89
90static void twidjoy_process_packet(struct twidjoy *twidjoy)
91{
92	struct input_dev *dev = twidjoy->dev;
93	unsigned char *data = twidjoy->data;
94	struct twidjoy_button_spec *bp;
95	int button_bits, abs_x, abs_y;
96
97	button_bits = ((data[1] & 0x7f) << 7) | (data[0] & 0x7f);
98
99	for (bp = twidjoy_buttons; bp->bitmask; bp++) {
100		int value = (button_bits & (bp->bitmask << bp->bitshift)) >> bp->bitshift;
101		int i;
102
103		for (i = 0; i < bp->bitmask; i++)
104			input_report_key(dev, bp->buttons[i], i+1 == value);
105	}
106
107	abs_x = ((data[4] & 0x07) << 5) | ((data[3] & 0x7C) >> 2);
108	if (data[4] & 0x08) abs_x -= 256;
109
110	abs_y = ((data[3] & 0x01) << 7) | ((data[2] & 0x7F) >> 0);
111	if (data[3] & 0x02) abs_y -= 256;
112
113	input_report_abs(dev, ABS_X, -abs_x);
114	input_report_abs(dev, ABS_Y, +abs_y);
115
116	input_sync(dev);
117}
118
119/*
120 * twidjoy_interrupt() is called by the low level driver when characters
121 * are ready for us. We then buffer them for further processing, or call the
122 * packet processing routine.
123 */
124
125static irqreturn_t twidjoy_interrupt(struct serio *serio, unsigned char data, unsigned int flags)
126{
127	struct twidjoy *twidjoy = serio_get_drvdata(serio);
128
129	/* All Twiddler packets are 5 bytes. The fact that the first byte
130	 * has a MSB of 0 and all other bytes have a MSB of 1 can be used
131	 * to check and regain sync. */
132
133	if ((data & 0x80) == 0)
134		twidjoy->idx = 0;	/* this byte starts a new packet */
135	else if (twidjoy->idx == 0)
136		return IRQ_HANDLED;	/* wrong MSB -- ignore this byte */
137
138	if (twidjoy->idx < TWIDJOY_MAX_LENGTH)
139		twidjoy->data[twidjoy->idx++] = data;
140
141	if (twidjoy->idx == TWIDJOY_MAX_LENGTH) {
142		twidjoy_process_packet(twidjoy);
143		twidjoy->idx = 0;
144	}
145
146	return IRQ_HANDLED;
147}
148
149/*
150 * twidjoy_disconnect() is the opposite of twidjoy_connect()
151 */
152
153static void twidjoy_disconnect(struct serio *serio)
154{
155	struct twidjoy *twidjoy = serio_get_drvdata(serio);
156
157	serio_close(serio);
158	serio_set_drvdata(serio, NULL);
159	input_unregister_device(twidjoy->dev);
160	kfree(twidjoy);
161}
162
163/*
164 * twidjoy_connect() is the routine that is called when someone adds a
165 * new serio device. It looks for the Twiddler, and if found, registers
166 * it as an input device.
167 */
168
169static int twidjoy_connect(struct serio *serio, struct serio_driver *drv)
170{
171	struct twidjoy_button_spec *bp;
172	struct twidjoy *twidjoy;
173	struct input_dev *input_dev;
174	int err = -ENOMEM;
175	int i;
176
177	twidjoy = kzalloc(sizeof(struct twidjoy), GFP_KERNEL);
178	input_dev = input_allocate_device();
179	if (!twidjoy || !input_dev)
180		goto fail1;
181
182	twidjoy->dev = input_dev;
183	snprintf(twidjoy->phys, sizeof(twidjoy->phys), "%s/input0", serio->phys);
184
185	input_dev->name = "Handykey Twiddler";
186	input_dev->phys = twidjoy->phys;
187	input_dev->id.bustype = BUS_RS232;
188	input_dev->id.vendor = SERIO_TWIDJOY;
189	input_dev->id.product = 0x0001;
190	input_dev->id.version = 0x0100;
191	input_dev->dev.parent = &serio->dev;
192
193	input_dev->evbit[0] = BIT_MASK(EV_KEY) | BIT_MASK(EV_ABS);
194	input_set_abs_params(input_dev, ABS_X, -50, 50, 4, 4);
195	input_set_abs_params(input_dev, ABS_Y, -50, 50, 4, 4);
196
197	for (bp = twidjoy_buttons; bp->bitmask; bp++)
198		for (i = 0; i < bp->bitmask; i++)
199			set_bit(bp->buttons[i], input_dev->keybit);
200
201	serio_set_drvdata(serio, twidjoy);
202
203	err = serio_open(serio, drv);
204	if (err)
205		goto fail2;
206
207	err = input_register_device(twidjoy->dev);
208	if (err)
209		goto fail3;
210
211	return 0;
212
213 fail3:	serio_close(serio);
214 fail2:	serio_set_drvdata(serio, NULL);
215 fail1:	input_free_device(input_dev);
216	kfree(twidjoy);
217	return err;
218}
219
220/*
221 * The serio driver structure.
222 */
223
224static const struct serio_device_id twidjoy_serio_ids[] = {
225	{
226		.type	= SERIO_RS232,
227		.proto	= SERIO_TWIDJOY,
228		.id	= SERIO_ANY,
229		.extra	= SERIO_ANY,
230	},
231	{ 0 }
232};
233
234MODULE_DEVICE_TABLE(serio, twidjoy_serio_ids);
235
236static struct serio_driver twidjoy_drv = {
237	.driver		= {
238		.name	= "twidjoy",
239	},
240	.description	= DRIVER_DESC,
241	.id_table	= twidjoy_serio_ids,
242	.interrupt	= twidjoy_interrupt,
243	.connect	= twidjoy_connect,
244	.disconnect	= twidjoy_disconnect,
245};
246
247module_serio_driver(twidjoy_drv);
248