linux/drivers/input/joystick/walkera0701.c
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   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
 299static int __init walkera0701_init(void)
 300{
 301        return parport_register_driver(&walkera0701_parport_driver);
 302}
 303
 304static void __exit walkera0701_exit(void)
 305{
 306        parport_unregister_driver(&walkera0701_parport_driver);
 307}
 308
 309module_init(walkera0701_init);
 310module_exit(walkera0701_exit);
 311