twidjoy.c

  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#include <linux/kernel.h>
 36#include <linux/module.h>
 37#include <linux/slab.h>
 38#include <linux/input.h>
 39#include <linux/serio.h>
 40
 41#define DRIVER_DESC	"Handykey Twiddler keyboard as a joystick driver"
 42
 43MODULE_DESCRIPTION(DRIVER_DESC);
 44MODULE_LICENSE("GPL");
 45
 46/*
 47 * Constants.
 48 */
 49
 50#define TWIDJOY_MAX_LENGTH 5
 51
 52static struct twidjoy_button_spec {
 53	int bitshift;
 54	int bitmask;
 55	int buttons[3];
 56}
 57twidjoy_buttons[] = {
 58	{  0, 3, { BTN_A,      BTN_B,     BTN_C    } },
 59	{  2, 3, { BTN_X,      BTN_Y,     BTN_Z    } },
 60	{  4, 3, { BTN_TL,     BTN_TR,    BTN_TR2  } },
 61	{  6, 3, { BTN_SELECT, BTN_START, BTN_MODE } },
 62	{  8, 1, { BTN_BASE5                       } },
 63	{  9, 1, { BTN_BASE                        } },
 64	{ 10, 1, { BTN_BASE3                       } },
 65	{ 11, 1, { BTN_BASE4                       } },
 66	{ 12, 1, { BTN_BASE2                       } },
 67	{ 13, 1, { BTN_BASE6                       } },
 68	{ 0,  0, { 0                               } }
 69};
 70
 71/*
 72 * Per-Twiddler data.
 73 */
 74
 75struct twidjoy {
 76	struct input_dev *dev;
 77	int idx;
 78	unsigned char data[TWIDJOY_MAX_LENGTH];
 79	char phys[32];
 80};
 81
 82/*
 83 * twidjoy_process_packet() decodes packets the driver receives from the
 84 * Twiddler. It updates the data accordingly.
 85 */
 86
 87static void twidjoy_process_packet(struct twidjoy *twidjoy)
 88{
 89	struct input_dev *dev = twidjoy->dev;
 90	unsigned char *data = twidjoy->data;
 91	struct twidjoy_button_spec *bp;
 92	int button_bits, abs_x, abs_y;
 93
 94	button_bits = ((data[1] & 0x7f) << 7) | (data[0] & 0x7f);
 95
 96	for (bp = twidjoy_buttons; bp->bitmask; bp++) {
 97		int value = (button_bits & (bp->bitmask << bp->bitshift)) >> bp->bitshift;
 98		int i;
 99
100		for (i = 0; i < bp->bitmask; i++)
101			input_report_key(dev, bp->buttons[i], i+1 == value);
102	}
103
104	abs_x = ((data[4] & 0x07) << 5) | ((data[3] & 0x7C) >> 2);
105	if (data[4] & 0x08) abs_x -= 256;
106
107	abs_y = ((data[3] & 0x01) << 7) | ((data[2] & 0x7F) >> 0);
108	if (data[3] & 0x02) abs_y -= 256;
109
110	input_report_abs(dev, ABS_X, -abs_x);
111	input_report_abs(dev, ABS_Y, +abs_y);
112
113	input_sync(dev);
114}
115
116/*
117 * twidjoy_interrupt() is called by the low level driver when characters
118 * are ready for us. We then buffer them for further processing, or call the
119 * packet processing routine.
120 */
121
122static irqreturn_t twidjoy_interrupt(struct serio *serio, unsigned char data, unsigned int flags)
123{
124	struct twidjoy *twidjoy = serio_get_drvdata(serio);
125
126	/* All Twiddler packets are 5 bytes. The fact that the first byte
127	 * has a MSB of 0 and all other bytes have a MSB of 1 can be used
128	 * to check and regain sync. */
129
130	if ((data & 0x80) == 0)
131		twidjoy->idx = 0;	/* this byte starts a new packet */
132	else if (twidjoy->idx == 0)
133		return IRQ_HANDLED;	/* wrong MSB -- ignore this byte */
134
135	if (twidjoy->idx < TWIDJOY_MAX_LENGTH)
136		twidjoy->data[twidjoy->idx++] = data;
137
138	if (twidjoy->idx == TWIDJOY_MAX_LENGTH) {
139		twidjoy_process_packet(twidjoy);
140		twidjoy->idx = 0;
141	}
142
143	return IRQ_HANDLED;
144}
145
146/*
147 * twidjoy_disconnect() is the opposite of twidjoy_connect()
148 */
149
150static void twidjoy_disconnect(struct serio *serio)
151{
152	struct twidjoy *twidjoy = serio_get_drvdata(serio);
153
154	serio_close(serio);
155	serio_set_drvdata(serio, NULL);
156	input_unregister_device(twidjoy->dev);
157	kfree(twidjoy);
158}
159
160/*
161 * twidjoy_connect() is the routine that is called when someone adds a
162 * new serio device. It looks for the Twiddler, and if found, registers
163 * it as an input device.
164 */
165
166static int twidjoy_connect(struct serio *serio, struct serio_driver *drv)
167{
168	struct twidjoy_button_spec *bp;
169	struct twidjoy *twidjoy;
170	struct input_dev *input_dev;
171	int err = -ENOMEM;
172	int i;
173
174	twidjoy = kzalloc(sizeof(*twidjoy), GFP_KERNEL);
175	input_dev = input_allocate_device();
176	if (!twidjoy || !input_dev)
177		goto fail1;
178
179	twidjoy->dev = input_dev;
180	snprintf(twidjoy->phys, sizeof(twidjoy->phys), "%s/input0", serio->phys);
181
182	input_dev->name = "Handykey Twiddler";
183	input_dev->phys = twidjoy->phys;
184	input_dev->id.bustype = BUS_RS232;
185	input_dev->id.vendor = SERIO_TWIDJOY;
186	input_dev->id.product = 0x0001;
187	input_dev->id.version = 0x0100;
188	input_dev->dev.parent = &serio->dev;
189
190	input_dev->evbit[0] = BIT_MASK(EV_KEY) | BIT_MASK(EV_ABS);
191	input_set_abs_params(input_dev, ABS_X, -50, 50, 4, 4);
192	input_set_abs_params(input_dev, ABS_Y, -50, 50, 4, 4);
193
194	for (bp = twidjoy_buttons; bp->bitmask; bp++)
195		for (i = 0; i < bp->bitmask; i++)
196			set_bit(bp->buttons[i], input_dev->keybit);
197
198	serio_set_drvdata(serio, twidjoy);
199
200	err = serio_open(serio, drv);
201	if (err)
202		goto fail2;
203
204	err = input_register_device(twidjoy->dev);
205	if (err)
206		goto fail3;
207
208	return 0;
209
210 fail3:	serio_close(serio);
211 fail2:	serio_set_drvdata(serio, NULL);
212 fail1:	input_free_device(input_dev);
213	kfree(twidjoy);
214	return err;
215}
216
217/*
218 * The serio driver structure.
219 */
220
221static const struct serio_device_id twidjoy_serio_ids[] = {
222	{
223		.type	= SERIO_RS232,
224		.proto	= SERIO_TWIDJOY,
225		.id	= SERIO_ANY,
226		.extra	= SERIO_ANY,
227	},
228	{ 0 }
229};
230
231MODULE_DEVICE_TABLE(serio, twidjoy_serio_ids);
232
233static struct serio_driver twidjoy_drv = {
234	.driver		= {
235		.name	= "twidjoy",
236	},
237	.description	= DRIVER_DESC,
238	.id_table	= twidjoy_serio_ids,
239	.interrupt	= twidjoy_interrupt,
240	.connect	= twidjoy_connect,
241	.disconnect	= twidjoy_disconnect,
242};
243
244module_serio_driver(twidjoy_drv);