1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3  *  Parallel port to Walkera WK-0701 TX joystick
4  *
5  *  Copyright (c) 2008 Peter Popovec
6  *
7  *  More about driver:  <file:Documentation/input/devices/walkera0701.rst>
8  */
9 
10 
11 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
12 
13 #define RESERVE 20000
14 #define SYNC_PULSE 1306000
15 #define BIN0_PULSE 288000
16 #define BIN1_PULSE 438000
17 
18 #define ANALOG_MIN_PULSE 318000
19 #define ANALOG_MAX_PULSE 878000
20 #define ANALOG_DELTA 80000
21 
22 #define BIN_SAMPLE ((BIN0_PULSE + BIN1_PULSE) / 2)
23 
24 #define NO_SYNC 25
25 
26 #include <linux/kernel.h>
27 #include <linux/module.h>
28 #include <linux/parport.h>
29 #include <linux/input.h>
30 #include <linux/hrtimer.h>
31 
32 MODULE_AUTHOR("Peter Popovec <popovec@fei.tuke.sk>");
33 MODULE_DESCRIPTION("Walkera WK-0701 TX as joystick");
34 MODULE_LICENSE("GPL");
35 
36 static unsigned int walkera0701_pp_no;
37 module_param_named(port, walkera0701_pp_no, int, 0);
38 MODULE_PARM_DESC(port,
39 		 "Parallel port adapter for Walkera WK-0701 TX (default is 0)");
40 
41 /*
42  * For now, only one device is supported, if somebody need more devices, code
43  * can be expanded, one struct walkera_dev per device must be allocated and
44  * set up by walkera0701_connect (release of device by walkera0701_disconnect)
45  */
46 
47 struct walkera_dev {
48 	unsigned char buf[25];
49 	u64 irq_time, irq_lasttime;
50 	int counter;
51 	int ack;
52 
53 	struct input_dev *input_dev;
54 	struct hrtimer timer;
55 
56 	struct parport *parport;
57 	struct pardevice *pardevice;
58 };
59 
60 static struct walkera_dev w_dev;
61 
walkera0701_parse_frame(struct walkera_dev * w)62 static inline void walkera0701_parse_frame(struct walkera_dev *w)
63 {
64 	int i;
65 	int val1, val2, val3, val4, val5, val6, val7, val8;
66 	int magic, magic_bit;
67 	int crc1, crc2;
68 
69 	for (crc1 = crc2 = i = 0; i < 10; i++) {
70 		crc1 += w->buf[i] & 7;
71 		crc2 += (w->buf[i] & 8) >> 3;
72 	}
73 	if ((w->buf[10] & 7) != (crc1 & 7))
74 		return;
75 	if (((w->buf[10] & 8) >> 3) != (((crc1 >> 3) + crc2) & 1))
76 		return;
77 	for (crc1 = crc2 = 0, i = 11; i < 23; i++) {
78 		crc1 += w->buf[i] & 7;
79 		crc2 += (w->buf[i] & 8) >> 3;
80 	}
81 	if ((w->buf[23] & 7) != (crc1 & 7))
82 		return;
83 	if (((w->buf[23] & 8) >> 3) != (((crc1 >> 3) + crc2) & 1))
84 		return;
85 	val1 = ((w->buf[0] & 7) * 256 + w->buf[1] * 16 + w->buf[2]) >> 2;
86 	val1 *= ((w->buf[0] >> 2) & 2) - 1;	/* sign */
87 	val2 = (w->buf[2] & 1) << 8 | (w->buf[3] << 4) | w->buf[4];
88 	val2 *= (w->buf[2] & 2) - 1;	/* sign */
89 	val3 = ((w->buf[5] & 7) * 256 + w->buf[6] * 16 + w->buf[7]) >> 2;
90 	val3 *= ((w->buf[5] >> 2) & 2) - 1;	/* sign */
91 	val4 = (w->buf[7] & 1) << 8 | (w->buf[8] << 4) | w->buf[9];
92 	val4 *= (w->buf[7] & 2) - 1;	/* sign */
93 	val5 = ((w->buf[11] & 7) * 256 + w->buf[12] * 16 + w->buf[13]) >> 2;
94 	val5 *= ((w->buf[11] >> 2) & 2) - 1;	/* sign */
95 	val6 = (w->buf[13] & 1) << 8 | (w->buf[14] << 4) | w->buf[15];
96 	val6 *= (w->buf[13] & 2) - 1;	/* sign */
97 	val7 = ((w->buf[16] & 7) * 256 + w->buf[17] * 16 + w->buf[18]) >> 2;
98 	val7 *= ((w->buf[16] >> 2) & 2) - 1;	/*sign */
99 	val8 = (w->buf[18] & 1) << 8 | (w->buf[19] << 4) | w->buf[20];
100 	val8 *= (w->buf[18] & 2) - 1;	/*sign */
101 
102 	magic = (w->buf[21] << 4) | w->buf[22];
103 	magic_bit = (w->buf[24] & 8) >> 3;
104 	pr_debug("%4d %4d %4d %4d  %4d %4d %4d %4d (magic %2x %d)\n",
105 		 val1, val2, val3, val4, val5, val6, val7, val8,
106 		 magic, magic_bit);
107 
108 	input_report_abs(w->input_dev, ABS_X, val2);
109 	input_report_abs(w->input_dev, ABS_Y, val1);
110 	input_report_abs(w->input_dev, ABS_Z, val6);
111 	input_report_abs(w->input_dev, ABS_THROTTLE, val3);
112 	input_report_abs(w->input_dev, ABS_RUDDER, val4);
113 	input_report_abs(w->input_dev, ABS_MISC, val7);
114 	input_report_key(w->input_dev, BTN_GEAR_DOWN, val5 > 0);
115 }
116 
read_ack(struct pardevice * p)117 static inline int read_ack(struct pardevice *p)
118 {
119 	return parport_read_status(p->port) & 0x40;
120 }
121 
122 /* falling edge, prepare to BIN value calculation */
walkera0701_irq_handler(void * handler_data)123 static void walkera0701_irq_handler(void *handler_data)
124 {
125 	u64 pulse_time;
126 	struct walkera_dev *w = handler_data;
127 
128 	w->irq_time = ktime_to_ns(ktime_get());
129 	pulse_time = w->irq_time - w->irq_lasttime;
130 	w->irq_lasttime = w->irq_time;
131 
132 	/* cancel timer, if in handler or active do resync */
133 	if (unlikely(0 != hrtimer_try_to_cancel(&w->timer))) {
134 		w->counter = NO_SYNC;
135 		return;
136 	}
137 
138 	if (w->counter < NO_SYNC) {
139 		if (w->ack) {
140 			pulse_time -= BIN1_PULSE;
141 			w->buf[w->counter] = 8;
142 		} else {
143 			pulse_time -= BIN0_PULSE;
144 			w->buf[w->counter] = 0;
145 		}
146 		if (w->counter == 24) {	/* full frame */
147 			walkera0701_parse_frame(w);
148 			w->counter = NO_SYNC;
149 			if (abs(pulse_time - SYNC_PULSE) < RESERVE)	/* new frame sync */
150 				w->counter = 0;
151 		} else {
152 			if ((pulse_time > (ANALOG_MIN_PULSE - RESERVE)
153 			     && (pulse_time < (ANALOG_MAX_PULSE + RESERVE)))) {
154 				pulse_time -= (ANALOG_MIN_PULSE - RESERVE);
155 				pulse_time = (u32) pulse_time / ANALOG_DELTA;	/* overtiping is safe, pulsetime < s32.. */
156 				w->buf[w->counter++] |= (pulse_time & 7);
157 			} else
158 				w->counter = NO_SYNC;
159 		}
160 	} else if (abs(pulse_time - SYNC_PULSE - BIN0_PULSE) <
161 				RESERVE + BIN1_PULSE - BIN0_PULSE)	/* frame sync .. */
162 		w->counter = 0;
163 
164 	hrtimer_start(&w->timer, BIN_SAMPLE, HRTIMER_MODE_REL);
165 }
166 
timer_handler(struct hrtimer * handle)167 static enum hrtimer_restart timer_handler(struct hrtimer
168 					  *handle)
169 {
170 	struct walkera_dev *w;
171 
172 	w = container_of(handle, struct walkera_dev, timer);
173 	w->ack = read_ack(w->pardevice);
174 
175 	return HRTIMER_NORESTART;
176 }
177 
walkera0701_open(struct input_dev * dev)178 static int walkera0701_open(struct input_dev *dev)
179 {
180 	struct walkera_dev *w = input_get_drvdata(dev);
181 
182 	if (parport_claim(w->pardevice))
183 		return -EBUSY;
184 
185 	parport_enable_irq(w->parport);
186 	return 0;
187 }
188 
walkera0701_close(struct input_dev * dev)189 static void walkera0701_close(struct input_dev *dev)
190 {
191 	struct walkera_dev *w = input_get_drvdata(dev);
192 
193 	parport_disable_irq(w->parport);
194 	hrtimer_cancel(&w->timer);
195 
196 	parport_release(w->pardevice);
197 }
198 
walkera0701_attach(struct parport * pp)199 static void walkera0701_attach(struct parport *pp)
200 {
201 	struct pardev_cb walkera0701_parport_cb;
202 	struct walkera_dev *w = &w_dev;
203 
204 	if (pp->number != walkera0701_pp_no) {
205 		pr_debug("Not using parport%d.\n", pp->number);
206 		return;
207 	}
208 
209 	if (pp->irq == -1) {
210 		pr_err("parport %d does not have interrupt assigned\n",
211 			pp->number);
212 		return;
213 	}
214 
215 	w->parport = pp;
216 
217 	memset(&walkera0701_parport_cb, 0, sizeof(walkera0701_parport_cb));
218 	walkera0701_parport_cb.flags = PARPORT_FLAG_EXCL;
219 	walkera0701_parport_cb.irq_func = walkera0701_irq_handler;
220 	walkera0701_parport_cb.private = w;
221 
222 	w->pardevice = parport_register_dev_model(pp, "walkera0701",
223 						  &walkera0701_parport_cb, 0);
224 
225 	if (!w->pardevice) {
226 		pr_err("failed to register parport device\n");
227 		return;
228 	}
229 
230 	if (parport_negotiate(w->pardevice->port, IEEE1284_MODE_COMPAT)) {
231 		pr_err("failed to negotiate parport mode\n");
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 		goto err_unregister_device;
242 	}
243 
244 	input_set_drvdata(w->input_dev, w);
245 	w->input_dev->name = "Walkera WK-0701 TX";
246 	w->input_dev->phys = w->parport->name;
247 	w->input_dev->id.bustype = BUS_PARPORT;
248 
249 	/* TODO what id vendor/product/version ? */
250 	w->input_dev->id.vendor = 0x0001;
251 	w->input_dev->id.product = 0x0001;
252 	w->input_dev->id.version = 0x0100;
253 	w->input_dev->dev.parent = w->parport->dev;
254 	w->input_dev->open = walkera0701_open;
255 	w->input_dev->close = walkera0701_close;
256 
257 	w->input_dev->evbit[0] = BIT(EV_ABS) | BIT_MASK(EV_KEY);
258 	w->input_dev->keybit[BIT_WORD(BTN_GEAR_DOWN)] = BIT_MASK(BTN_GEAR_DOWN);
259 
260 	input_set_abs_params(w->input_dev, ABS_X, -512, 512, 0, 0);
261 	input_set_abs_params(w->input_dev, ABS_Y, -512, 512, 0, 0);
262 	input_set_abs_params(w->input_dev, ABS_Z, -512, 512, 0, 0);
263 	input_set_abs_params(w->input_dev, ABS_THROTTLE, -512, 512, 0, 0);
264 	input_set_abs_params(w->input_dev, ABS_RUDDER, -512, 512, 0, 0);
265 	input_set_abs_params(w->input_dev, ABS_MISC, -512, 512, 0, 0);
266 
267 	if (input_register_device(w->input_dev)) {
268 		pr_err("failed to register input device\n");
269 		goto err_free_input_dev;
270 	}
271 
272 	return;
273 
274 err_free_input_dev:
275 	input_free_device(w->input_dev);
276 err_unregister_device:
277 	parport_unregister_device(w->pardevice);
278 }
279 
walkera0701_detach(struct parport * port)280 static void walkera0701_detach(struct parport *port)
281 {
282 	struct walkera_dev *w = &w_dev;
283 
284 	if (!w->pardevice || w->parport->number != port->number)
285 		return;
286 
287 	input_unregister_device(w->input_dev);
288 	parport_unregister_device(w->pardevice);
289 	w->parport = NULL;
290 }
291 
292 static struct parport_driver walkera0701_parport_driver = {
293 	.name = "walkera0701",
294 	.match_port = walkera0701_attach,
295 	.detach = walkera0701_detach,
296 	.devmodel = true,
297 };
298 
walkera0701_init(void)299 static int __init walkera0701_init(void)
300 {
301 	return parport_register_driver(&walkera0701_parport_driver);
302 }
303 
walkera0701_exit(void)304 static void __exit walkera0701_exit(void)
305 {
306 	parport_unregister_driver(&walkera0701_parport_driver);
307 }
308 
309 module_init(walkera0701_init);
310 module_exit(walkera0701_exit);
311