1/*
2 *  Parallel port to Walkera WK-0701 TX joystick
3 *
4 *  Copyright (c) 2008 Peter Popovec
5 *
6 *  More about driver:  <file:Documentation/input/walkera0701.txt>
7 */
8
9/*
10 * This program is free software; you can redistribute it and/or modify it
11 * under the terms of the GNU General Public License version 2 as published by
12 * the Free Software Foundation.
13*/
14
15/* #define WK0701_DEBUG */
16
17#define RESERVE 20000
18#define SYNC_PULSE 1306000
19#define BIN0_PULSE 288000
20#define BIN1_PULSE 438000
21
22#define ANALOG_MIN_PULSE 318000
23#define ANALOG_MAX_PULSE 878000
24#define ANALOG_DELTA 80000
25
26#define BIN_SAMPLE ((BIN0_PULSE + BIN1_PULSE) / 2)
27
28#define NO_SYNC 25
29
30#include <linux/kernel.h>
31#include <linux/module.h>
32#include <linux/parport.h>
33#include <linux/input.h>
34#include <linux/hrtimer.h>
35
36MODULE_AUTHOR("Peter Popovec <popovec@fei.tuke.sk>");
37MODULE_DESCRIPTION("Walkera WK-0701 TX as joystick");
38MODULE_LICENSE("GPL");
39
40static unsigned int walkera0701_pp_no;
41module_param_named(port, walkera0701_pp_no, int, 0);
42MODULE_PARM_DESC(port,
43		 "Parallel port adapter for Walkera WK-0701 TX (default is 0)");
44
45/*
46 * For now, only one device is supported, if somebody need more devices, code
47 * can be expanded, one struct walkera_dev per device must be allocated and
48 * set up by walkera0701_connect (release of device by walkera0701_disconnect)
49 */
50
51struct walkera_dev {
52	unsigned char buf[25];
53	u64 irq_time, irq_lasttime;
54	int counter;
55	int ack;
56
57	struct input_dev *input_dev;
58	struct hrtimer timer;
59
60	struct parport *parport;
61	struct pardevice *pardevice;
62};
63
64static struct walkera_dev w_dev;
65
66static inline void walkera0701_parse_frame(struct walkera_dev *w)
67{
68	int i;
69	int val1, val2, val3, val4, val5, val6, val7, val8;
70	int crc1, crc2;
71
72	for (crc1 = crc2 = i = 0; i < 10; i++) {
73		crc1 += w->buf[i] & 7;
74		crc2 += (w->buf[i] & 8) >> 3;
75	}
76	if ((w->buf[10] & 7) != (crc1 & 7))
77		return;
78	if (((w->buf[10] & 8) >> 3) != (((crc1 >> 3) + crc2) & 1))
79		return;
80	for (crc1 = crc2 = 0, i = 11; i < 23; i++) {
81		crc1 += w->buf[i] & 7;
82		crc2 += (w->buf[i] & 8) >> 3;
83	}
84	if ((w->buf[23] & 7) != (crc1 & 7))
85		return;
86	if (((w->buf[23] & 8) >> 3) != (((crc1 >> 3) + crc2) & 1))
87		return;
88	val1 = ((w->buf[0] & 7) * 256 + w->buf[1] * 16 + w->buf[2]) >> 2;
89	val1 *= ((w->buf[0] >> 2) & 2) - 1;	/* sign */
90	val2 = (w->buf[2] & 1) << 8 | (w->buf[3] << 4) | w->buf[4];
91	val2 *= (w->buf[2] & 2) - 1;	/* sign */
92	val3 = ((w->buf[5] & 7) * 256 + w->buf[6] * 16 + w->buf[7]) >> 2;
93	val3 *= ((w->buf[5] >> 2) & 2) - 1;	/* sign */
94	val4 = (w->buf[7] & 1) << 8 | (w->buf[8] << 4) | w->buf[9];
95	val4 *= (w->buf[7] & 2) - 1;	/* sign */
96	val5 = ((w->buf[11] & 7) * 256 + w->buf[12] * 16 + w->buf[13]) >> 2;
97	val5 *= ((w->buf[11] >> 2) & 2) - 1;	/* sign */
98	val6 = (w->buf[13] & 1) << 8 | (w->buf[14] << 4) | w->buf[15];
99	val6 *= (w->buf[13] & 2) - 1;	/* sign */
100	val7 = ((w->buf[16] & 7) * 256 + w->buf[17] * 16 + w->buf[18]) >> 2;
101	val7 *= ((w->buf[16] >> 2) & 2) - 1;	/*sign */
102	val8 = (w->buf[18] & 1) << 8 | (w->buf[19] << 4) | w->buf[20];
103	val8 *= (w->buf[18] & 2) - 1;	/*sign */
104
105#ifdef WK0701_DEBUG
106	{
107		int magic, magic_bit;
108		magic = (w->buf[21] << 4) | w->buf[22];
109		magic_bit = (w->buf[24] & 8) >> 3;
110		printk(KERN_DEBUG
111		       "walkera0701: %4d %4d %4d %4d  %4d %4d %4d %4d (magic %2x %d)\n",
112		       val1, val2, val3, val4, val5, val6, val7, val8, magic,
113		       magic_bit);
114	}
115#endif
116	input_report_abs(w->input_dev, ABS_X, val2);
117	input_report_abs(w->input_dev, ABS_Y, val1);
118	input_report_abs(w->input_dev, ABS_Z, val6);
119	input_report_abs(w->input_dev, ABS_THROTTLE, val3);
120	input_report_abs(w->input_dev, ABS_RUDDER, val4);
121	input_report_abs(w->input_dev, ABS_MISC, val7);
122	input_report_key(w->input_dev, BTN_GEAR_DOWN, val5 > 0);
123}
124
125static inline int read_ack(struct pardevice *p)
126{
127	return parport_read_status(p->port) & 0x40;
128}
129
130/* falling edge, prepare to BIN value calculation */
131static void walkera0701_irq_handler(void *handler_data)
132{
133	u64 pulse_time;
134	struct walkera_dev *w = handler_data;
135
136	w->irq_time = ktime_to_ns(ktime_get());
137	pulse_time = w->irq_time - w->irq_lasttime;
138	w->irq_lasttime = w->irq_time;
139
140	/* cancel timer, if in handler or active do resync */
141	if (unlikely(0 != hrtimer_try_to_cancel(&w->timer))) {
142		w->counter = NO_SYNC;
143		return;
144	}
145
146	if (w->counter < NO_SYNC) {
147		if (w->ack) {
148			pulse_time -= BIN1_PULSE;
149			w->buf[w->counter] = 8;
150		} else {
151			pulse_time -= BIN0_PULSE;
152			w->buf[w->counter] = 0;
153		}
154		if (w->counter == 24) {	/* full frame */
155			walkera0701_parse_frame(w);
156			w->counter = NO_SYNC;
157			if (abs(pulse_time - SYNC_PULSE) < RESERVE)	/* new frame sync */
158				w->counter = 0;
159		} else {
160			if ((pulse_time > (ANALOG_MIN_PULSE - RESERVE)
161			     && (pulse_time < (ANALOG_MAX_PULSE + RESERVE)))) {
162				pulse_time -= (ANALOG_MIN_PULSE - RESERVE);
163				pulse_time = (u32) pulse_time / ANALOG_DELTA;	/* overtiping is safe, pulsetime < s32.. */
164				w->buf[w->counter++] |= (pulse_time & 7);
165			} else
166				w->counter = NO_SYNC;
167		}
168	} else if (abs(pulse_time - SYNC_PULSE - BIN0_PULSE) <
169				RESERVE + BIN1_PULSE - BIN0_PULSE)	/* frame sync .. */
170		w->counter = 0;
171
172	hrtimer_start(&w->timer, ktime_set(0, BIN_SAMPLE), HRTIMER_MODE_REL);
173}
174
175static enum hrtimer_restart timer_handler(struct hrtimer
176					  *handle)
177{
178	struct walkera_dev *w;
179
180	w = container_of(handle, struct walkera_dev, timer);
181	w->ack = read_ack(w->pardevice);
182
183	return HRTIMER_NORESTART;
184}
185
186static int walkera0701_open(struct input_dev *dev)
187{
188	struct walkera_dev *w = input_get_drvdata(dev);
189
190	parport_enable_irq(w->parport);
191	return 0;
192}
193
194static void walkera0701_close(struct input_dev *dev)
195{
196	struct walkera_dev *w = input_get_drvdata(dev);
197
198	parport_disable_irq(w->parport);
199}
200
201static int walkera0701_connect(struct walkera_dev *w, int parport)
202{
203	int err = -ENODEV;
204
205	w->parport = parport_find_number(parport);
206	if (w->parport == NULL)
207		return -ENODEV;
208
209	if (w->parport->irq == -1) {
210		printk(KERN_ERR "walkera0701: parport without interrupt\n");
211		goto init_err;
212	}
213
214	err = -EBUSY;
215	w->pardevice = parport_register_device(w->parport, "walkera0701",
216				    NULL, NULL, walkera0701_irq_handler,
217				    PARPORT_DEV_EXCL, w);
218	if (!w->pardevice)
219		goto init_err;
220
221	if (parport_negotiate(w->pardevice->port, IEEE1284_MODE_COMPAT))
222		goto init_err1;
223
224	if (parport_claim(w->pardevice))
225		goto init_err1;
226
227	w->input_dev = input_allocate_device();
228	if (!w->input_dev)
229		goto init_err2;
230
231	input_set_drvdata(w->input_dev, w);
232	w->input_dev->name = "Walkera WK-0701 TX";
233	w->input_dev->phys = w->parport->name;
234	w->input_dev->id.bustype = BUS_PARPORT;
235
236	/* TODO what id vendor/product/version ? */
237	w->input_dev->id.vendor = 0x0001;
238	w->input_dev->id.product = 0x0001;
239	w->input_dev->id.version = 0x0100;
240	w->input_dev->open = walkera0701_open;
241	w->input_dev->close = walkera0701_close;
242
243	w->input_dev->evbit[0] = BIT(EV_ABS) | BIT_MASK(EV_KEY);
244	w->input_dev->keybit[BIT_WORD(BTN_GEAR_DOWN)] = BIT_MASK(BTN_GEAR_DOWN);
245
246	input_set_abs_params(w->input_dev, ABS_X, -512, 512, 0, 0);
247	input_set_abs_params(w->input_dev, ABS_Y, -512, 512, 0, 0);
248	input_set_abs_params(w->input_dev, ABS_Z, -512, 512, 0, 0);
249	input_set_abs_params(w->input_dev, ABS_THROTTLE, -512, 512, 0, 0);
250	input_set_abs_params(w->input_dev, ABS_RUDDER, -512, 512, 0, 0);
251	input_set_abs_params(w->input_dev, ABS_MISC, -512, 512, 0, 0);
252
253	err = input_register_device(w->input_dev);
254	if (err)
255		goto init_err3;
256
257	hrtimer_init(&w->timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
258	w->timer.function = timer_handler;
259	return 0;
260
261 init_err3:
262	input_free_device(w->input_dev);
263 init_err2:
264	parport_release(w->pardevice);
265 init_err1:
266	parport_unregister_device(w->pardevice);
267 init_err:
268	parport_put_port(w->parport);
269	return err;
270}
271
272static void walkera0701_disconnect(struct walkera_dev *w)
273{
274	hrtimer_cancel(&w->timer);
275	input_unregister_device(w->input_dev);
276	parport_release(w->pardevice);
277	parport_unregister_device(w->pardevice);
278	parport_put_port(w->parport);
279}
280
281static int __init walkera0701_init(void)
282{
283	return walkera0701_connect(&w_dev, walkera0701_pp_no);
284}
285
286static void __exit walkera0701_exit(void)
287{
288	walkera0701_disconnect(&w_dev);
289}
290
291module_init(walkera0701_init);
292module_exit(walkera0701_exit);
293