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/devices/walkera0701.rst>
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, 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 void walkera0701_attach(struct parport *pp)
204{
205 struct pardev_cb walkera0701_parport_cb;
206 struct walkera_dev *w = &w_dev;
207
208 if (pp->number != walkera0701_pp_no) {
209 pr_debug("Not using parport%d.\n", pp->number);
210 return;
211 }
212
213 if (pp->irq == -1) {
214 pr_err("parport %d does not have interrupt assigned\n",
215 pp->number);
216 return;
217 }
218
219 w->parport = pp;
220
221 memset(&walkera0701_parport_cb, 0, sizeof(walkera0701_parport_cb));
222 walkera0701_parport_cb.flags = PARPORT_FLAG_EXCL;
223 walkera0701_parport_cb.irq_func = walkera0701_irq_handler;
224 walkera0701_parport_cb.private = w;
225
226 w->pardevice = parport_register_dev_model(pp, "walkera0701",
227 &walkera0701_parport_cb, 0);
228
229 if (!w->pardevice) {
230 pr_err("failed to register parport device\n");
231 return;
232 }
233
234 if (parport_negotiate(w->pardevice->port, IEEE1284_MODE_COMPAT)) {
235 pr_err("failed to negotiate parport mode\n");
236 goto err_unregister_device;
237 }
238
239 hrtimer_init(&w->timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
240 w->timer.function = timer_handler;
241
242 w->input_dev = input_allocate_device();
243 if (!w->input_dev) {
244 pr_err("failed to allocate input device\n");
245 goto err_unregister_device;
246 }
247
248 input_set_drvdata(w->input_dev, w);
249 w->input_dev->name = "Walkera WK-0701 TX";
250 w->input_dev->phys = w->parport->name;
251 w->input_dev->id.bustype = BUS_PARPORT;
252
253 /* TODO what id vendor/product/version ? */
254 w->input_dev->id.vendor = 0x0001;
255 w->input_dev->id.product = 0x0001;
256 w->input_dev->id.version = 0x0100;
257 w->input_dev->dev.parent = w->parport->dev;
258 w->input_dev->open = walkera0701_open;
259 w->input_dev->close = walkera0701_close;
260
261 w->input_dev->evbit[0] = BIT(EV_ABS) | BIT_MASK(EV_KEY);
262 w->input_dev->keybit[BIT_WORD(BTN_GEAR_DOWN)] = BIT_MASK(BTN_GEAR_DOWN);
263
264 input_set_abs_params(w->input_dev, ABS_X, -512, 512, 0, 0);
265 input_set_abs_params(w->input_dev, ABS_Y, -512, 512, 0, 0);
266 input_set_abs_params(w->input_dev, ABS_Z, -512, 512, 0, 0);
267 input_set_abs_params(w->input_dev, ABS_THROTTLE, -512, 512, 0, 0);
268 input_set_abs_params(w->input_dev, ABS_RUDDER, -512, 512, 0, 0);
269 input_set_abs_params(w->input_dev, ABS_MISC, -512, 512, 0, 0);
270
271 if (input_register_device(w->input_dev)) {
272 pr_err("failed to register input device\n");
273 goto err_free_input_dev;
274 }
275
276 return;
277
278err_free_input_dev:
279 input_free_device(w->input_dev);
280err_unregister_device:
281 parport_unregister_device(w->pardevice);
282}
283
284static void walkera0701_detach(struct parport *port)
285{
286 struct walkera_dev *w = &w_dev;
287
288 if (!w->pardevice || w->parport->number != port->number)
289 return;
290
291 input_unregister_device(w->input_dev);
292 parport_unregister_device(w->pardevice);
293 w->parport = NULL;
294}
295
296static struct parport_driver walkera0701_parport_driver = {
297 .name = "walkera0701",
298 .match_port = walkera0701_attach,
299 .detach = walkera0701_detach,
300 .devmodel = true,
301};
302
303static int __init walkera0701_init(void)
304{
305 return parport_register_driver(&walkera0701_parport_driver);
306}
307
308static void __exit walkera0701_exit(void)
309{
310 parport_unregister_driver(&walkera0701_parport_driver);
311}
312
313module_init(walkera0701_init);
314module_exit(walkera0701_exit);
315