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walkera0701.c
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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 <[email protected]>");
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);
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