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 
36 MODULE_AUTHOR("Peter Popovec <popovec@fei.tuke.sk>");
37 MODULE_DESCRIPTION("Walkera WK-0701 TX as joystick");
38 MODULE_LICENSE("GPL");
39 
40 static unsigned int walkera0701_pp_no;
41 module_param_named(port, walkera0701_pp_no, int, 0);
42 MODULE_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 
51 struct 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 
64 static struct walkera_dev w_dev;
65 
66 static 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 
125 static 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 */
131 static 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 
175 static 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 
186 static 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 
194 static 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 
201 static 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 
272 static 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 
281 static int __init walkera0701_init(void)
282 {
283 	return walkera0701_connect(&w_dev, walkera0701_pp_no);
284 }
285 
286 static void __exit walkera0701_exit(void)
287 {
288 	walkera0701_disconnect(&w_dev);
289 }
290 
291 module_init(walkera0701_init);
292 module_exit(walkera0701_exit);
293