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
32MODULE_AUTHOR("Peter Popovec <popovec@fei.tuke.sk>");
33MODULE_DESCRIPTION("Walkera WK-0701 TX as joystick");
34MODULE_LICENSE("GPL");
35
36static unsigned int walkera0701_pp_no;
37module_param_named(port, walkera0701_pp_no, int, 0);
38MODULE_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
47struct 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
60static struct walkera_dev w_dev;
61
62static 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
117static 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 */
123static 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
167static 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
178static 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
189static 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
199static 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
274err_free_input_dev:
275	input_free_device(w->input_dev);
276err_unregister_device:
277	parport_unregister_device(w->pardevice);
278}
279
280static 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
292static struct parport_driver walkera0701_parport_driver = {
293	.name = "walkera0701",
294	.match_port = walkera0701_attach,
295	.detach = walkera0701_detach,
296	.devmodel = true,
297};
298
299module_parport_driver(walkera0701_parport_driver);
300