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 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 } 116 117 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 */ 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 } 166 167 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 } 177 178 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 } 188 189 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 } 198 199 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 } 279 280 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 }; 297 298 module_parport_driver(walkera0701_parport_driver); 299