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 pr_fmt(fmt) KBUILD_MODNAME ": " fmt
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 magic, magic_bit;
71	int crc1, crc2;
72
73	for (crc1 = crc2 = i = 0; i < 10; i++) {
74		crc1 += w->buf[i] & 7;
75		crc2 += (w->buf[i] & 8) >> 3;
76	}
77	if ((w->buf[10] & 7) != (crc1 & 7))
78		return;
79	if (((w->buf[10] & 8) >> 3) != (((crc1 >> 3) + crc2) & 1))
80		return;
81	for (crc1 = crc2 = 0, i = 11; i < 23; i++) {
82		crc1 += w->buf[i] & 7;
83		crc2 += (w->buf[i] & 8) >> 3;
84	}
85	if ((w->buf[23] & 7) != (crc1 & 7))
86		return;
87	if (((w->buf[23] & 8) >> 3) != (((crc1 >> 3) + crc2) & 1))
88		return;
89	val1 = ((w->buf[0] & 7) * 256 + w->buf[1] * 16 + w->buf[2]) >> 2;
90	val1 *= ((w->buf[0] >> 2) & 2) - 1;	/* sign */
91	val2 = (w->buf[2] & 1) << 8 | (w->buf[3] << 4) | w->buf[4];
92	val2 *= (w->buf[2] & 2) - 1;	/* sign */
93	val3 = ((w->buf[5] & 7) * 256 + w->buf[6] * 16 + w->buf[7]) >> 2;
94	val3 *= ((w->buf[5] >> 2) & 2) - 1;	/* sign */
95	val4 = (w->buf[7] & 1) << 8 | (w->buf[8] << 4) | w->buf[9];
96	val4 *= (w->buf[7] & 2) - 1;	/* sign */
97	val5 = ((w->buf[11] & 7) * 256 + w->buf[12] * 16 + w->buf[13]) >> 2;
98	val5 *= ((w->buf[11] >> 2) & 2) - 1;	/* sign */
99	val6 = (w->buf[13] & 1) << 8 | (w->buf[14] << 4) | w->buf[15];
100	val6 *= (w->buf[13] & 2) - 1;	/* sign */
101	val7 = ((w->buf[16] & 7) * 256 + w->buf[17] * 16 + w->buf[18]) >> 2;
102	val7 *= ((w->buf[16] >> 2) & 2) - 1;	/*sign */
103	val8 = (w->buf[18] & 1) << 8 | (w->buf[19] << 4) | w->buf[20];
104	val8 *= (w->buf[18] & 2) - 1;	/*sign */
105
106	magic = (w->buf[21] << 4) | w->buf[22];
107	magic_bit = (w->buf[24] & 8) >> 3;
108	pr_debug("%4d %4d %4d %4d  %4d %4d %4d %4d (magic %2x %d)\n",
109		 val1, val2, val3, val4, val5, val6, val7, val8,
110		 magic, magic_bit);
111
112	input_report_abs(w->input_dev, ABS_X, val2);
113	input_report_abs(w->input_dev, ABS_Y, val1);
114	input_report_abs(w->input_dev, ABS_Z, val6);
115	input_report_abs(w->input_dev, ABS_THROTTLE, val3);
116	input_report_abs(w->input_dev, ABS_RUDDER, val4);
117	input_report_abs(w->input_dev, ABS_MISC, val7);
118	input_report_key(w->input_dev, BTN_GEAR_DOWN, val5 > 0);
119}
120
121static inline int read_ack(struct pardevice *p)
122{
123	return parport_read_status(p->port) & 0x40;
124}
125
126/* falling edge, prepare to BIN value calculation */
127static void walkera0701_irq_handler(void *handler_data)
128{
129	u64 pulse_time;
130	struct walkera_dev *w = handler_data;
131
132	w->irq_time = ktime_to_ns(ktime_get());
133	pulse_time = w->irq_time - w->irq_lasttime;
134	w->irq_lasttime = w->irq_time;
135
136	/* cancel timer, if in handler or active do resync */
137	if (unlikely(0 != hrtimer_try_to_cancel(&w->timer))) {
138		w->counter = NO_SYNC;
139		return;
140	}
141
142	if (w->counter < NO_SYNC) {
143		if (w->ack) {
144			pulse_time -= BIN1_PULSE;
145			w->buf[w->counter] = 8;
146		} else {
147			pulse_time -= BIN0_PULSE;
148			w->buf[w->counter] = 0;
149		}
150		if (w->counter == 24) {	/* full frame */
151			walkera0701_parse_frame(w);
152			w->counter = NO_SYNC;
153			if (abs(pulse_time - SYNC_PULSE) < RESERVE)	/* new frame sync */
154				w->counter = 0;
155		} else {
156			if ((pulse_time > (ANALOG_MIN_PULSE - RESERVE)
157			     && (pulse_time < (ANALOG_MAX_PULSE + RESERVE)))) {
158				pulse_time -= (ANALOG_MIN_PULSE - RESERVE);
159				pulse_time = (u32) pulse_time / ANALOG_DELTA;	/* overtiping is safe, pulsetime < s32.. */
160				w->buf[w->counter++] |= (pulse_time & 7);
161			} else
162				w->counter = NO_SYNC;
163		}
164	} else if (abs(pulse_time - SYNC_PULSE - BIN0_PULSE) <
165				RESERVE + BIN1_PULSE - BIN0_PULSE)	/* frame sync .. */
166		w->counter = 0;
167
168	hrtimer_start(&w->timer, ktime_set(0, BIN_SAMPLE), HRTIMER_MODE_REL);
169}
170
171static enum hrtimer_restart timer_handler(struct hrtimer
172					  *handle)
173{
174	struct walkera_dev *w;
175
176	w = container_of(handle, struct walkera_dev, timer);
177	w->ack = read_ack(w->pardevice);
178
179	return HRTIMER_NORESTART;
180}
181
182static int walkera0701_open(struct input_dev *dev)
183{
184	struct walkera_dev *w = input_get_drvdata(dev);
185
186	if (parport_claim(w->pardevice))
187		return -EBUSY;
188
189	parport_enable_irq(w->parport);
190	return 0;
191}
192
193static void walkera0701_close(struct input_dev *dev)
194{
195	struct walkera_dev *w = input_get_drvdata(dev);
196
197	parport_disable_irq(w->parport);
198	hrtimer_cancel(&w->timer);
199
200	parport_release(w->pardevice);
201}
202
203static int walkera0701_connect(struct walkera_dev *w, int parport)
204{
205	int error;
206
207	w->parport = parport_find_number(parport);
208	if (!w->parport) {
209		pr_err("parport %d does not exist\n", parport);
210		return -ENODEV;
211	}
212
213	if (w->parport->irq == -1) {
214		pr_err("parport %d does not have interrupt assigned\n",
215			parport);
216		error = -EINVAL;
217		goto err_put_parport;
218	}
219
220	w->pardevice = parport_register_device(w->parport, "walkera0701",
221				    NULL, NULL, walkera0701_irq_handler,
222				    PARPORT_DEV_EXCL, w);
223	if (!w->pardevice) {
224		pr_err("failed to register parport device\n");
225		error = -EIO;
226		goto err_put_parport;
227	}
228
229	if (parport_negotiate(w->pardevice->port, IEEE1284_MODE_COMPAT)) {
230		pr_err("failed to negotiate parport mode\n");
231		error = -EIO;
232		goto err_unregister_device;
233	}
234
235	hrtimer_init(&w->timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
236	w->timer.function = timer_handler;
237
238	w->input_dev = input_allocate_device();
239	if (!w->input_dev) {
240		pr_err("failed to allocate input device\n");
241		error = -ENOMEM;
242		goto err_unregister_device;
243	}
244
245	input_set_drvdata(w->input_dev, w);
246	w->input_dev->name = "Walkera WK-0701 TX";
247	w->input_dev->phys = w->parport->name;
248	w->input_dev->id.bustype = BUS_PARPORT;
249
250	/* TODO what id vendor/product/version ? */
251	w->input_dev->id.vendor = 0x0001;
252	w->input_dev->id.product = 0x0001;
253	w->input_dev->id.version = 0x0100;
254	w->input_dev->dev.parent = w->parport->dev;
255	w->input_dev->open = walkera0701_open;
256	w->input_dev->close = walkera0701_close;
257
258	w->input_dev->evbit[0] = BIT(EV_ABS) | BIT_MASK(EV_KEY);
259	w->input_dev->keybit[BIT_WORD(BTN_GEAR_DOWN)] = BIT_MASK(BTN_GEAR_DOWN);
260
261	input_set_abs_params(w->input_dev, ABS_X, -512, 512, 0, 0);
262	input_set_abs_params(w->input_dev, ABS_Y, -512, 512, 0, 0);
263	input_set_abs_params(w->input_dev, ABS_Z, -512, 512, 0, 0);
264	input_set_abs_params(w->input_dev, ABS_THROTTLE, -512, 512, 0, 0);
265	input_set_abs_params(w->input_dev, ABS_RUDDER, -512, 512, 0, 0);
266	input_set_abs_params(w->input_dev, ABS_MISC, -512, 512, 0, 0);
267
268	error = input_register_device(w->input_dev);
269	if (error) {
270		pr_err("failed to register input device\n");
271		goto err_free_input_dev;
272	}
273
274	return 0;
275
276err_free_input_dev:
277	input_free_device(w->input_dev);
278err_unregister_device:
279	parport_unregister_device(w->pardevice);
280err_put_parport:
281	parport_put_port(w->parport);
282	return error;
283}
284
285static void walkera0701_disconnect(struct walkera_dev *w)
286{
287	input_unregister_device(w->input_dev);
288	parport_unregister_device(w->pardevice);
289	parport_put_port(w->parport);
290}
291
292static int __init walkera0701_init(void)
293{
294	return walkera0701_connect(&w_dev, walkera0701_pp_no);
295}
296
297static void __exit walkera0701_exit(void)
298{
299	walkera0701_disconnect(&w_dev);
300}
301
302module_init(walkera0701_init);
303module_exit(walkera0701_exit);
304