drivers/media/rc/ir-imon-decoder.c

   1 // SPDX-License-Identifier: GPL-2.0+
   2 // ir-imon-decoder.c - handle iMon protocol
   3 //
   4 // Copyright (C) 2018 by Sean Young <sean@mess.org>
   5
   6 #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
   7
   8 #include <linux/module.h>
   9 #include "rc-core-priv.h"
  10
  11 #define IMON_UNIT               415662 /* ns */
  12 #define IMON_BITS               30
  13 #define IMON_CHKBITS            (BIT(30) | BIT(25) | BIT(24) | BIT(22) | \
  14                                  BIT(21) | BIT(20) | BIT(19) | BIT(18) | \
  15                                  BIT(17) | BIT(16) | BIT(14) | BIT(13) | \
  16                                  BIT(12) | BIT(11) | BIT(10) | BIT(9))
  17
  18 /*
  19  * This protocol has 30 bits. The format is one IMON_UNIT header pulse,
  20  * followed by 30 bits. Each bit is one IMON_UNIT check field, and then
  21  * one IMON_UNIT field with the actual bit (1=space, 0=pulse).
  22  * The check field is always space for some bits, for others it is pulse if
  23  * both the preceding and current bit are zero, else space. IMON_CHKBITS
  24  * defines which bits are of type check.
  25  *
  26  * There is no way to distinguish an incomplete message from one where
  27  * the lower bits are all set, iow. the last pulse is for the lowest
  28  * bit which is 0.
  29  */
  30 enum imon_state {
  31         STATE_INACTIVE,
  32         STATE_BIT_CHK,
  33         STATE_BIT_START,
  34         STATE_FINISHED,
  35         STATE_ERROR,
  36 };
  37
  38 static void ir_imon_decode_scancode(struct rc_dev *dev)
  39 {
  40         struct imon_dec *imon = &dev->raw->imon;
  41
  42         /* Keyboard/Mouse toggle */
  43         if (imon->bits == 0x299115b7)
  44                 imon->stick_keyboard = !imon->stick_keyboard;
  45
  46         if ((imon->bits & 0xfc0000ff) == 0x680000b7) {
  47                 int rel_x, rel_y;
  48                 u8 buf;
  49
  50                 buf = imon->bits >> 16;
  51                 rel_x = (buf & 0x08) | (buf & 0x10) >> 2 |
  52                         (buf & 0x20) >> 4 | (buf & 0x40) >> 6;
  53                 if (imon->bits & 0x02000000)
  54                         rel_x |= ~0x0f;
  55                 buf = imon->bits >> 8;
  56                 rel_y = (buf & 0x08) | (buf & 0x10) >> 2 |
  57                         (buf & 0x20) >> 4 | (buf & 0x40) >> 6;
  58                 if (imon->bits & 0x01000000)
  59                         rel_y |= ~0x0f;
  60
  61                 if (rel_x && rel_y && imon->stick_keyboard) {
  62                         if (abs(rel_y) > abs(rel_x))
  63                                 imon->bits = rel_y > 0 ?
  64                                         0x289515b7 : /* KEY_DOWN */
  65                                         0x2aa515b7;  /* KEY_UP */
  66                         else
  67                                 imon->bits = rel_x > 0 ?
  68                                         0x2ba515b7 : /* KEY_RIGHT */
  69                                         0x29a515b7;  /* KEY_LEFT */
  70                 }
  71
  72                 if (!imon->stick_keyboard) {
  73                         struct lirc_scancode lsc = {
  74                                 .scancode = imon->bits,
  75                                 .rc_proto = RC_PROTO_IMON,
  76                         };
  77
  78                         ir_lirc_scancode_event(dev, &lsc);
  79
  80                         input_event(imon->idev, EV_MSC, MSC_SCAN, imon->bits);
  81
  82                         input_report_rel(imon->idev, REL_X, rel_x);
  83                         input_report_rel(imon->idev, REL_Y, rel_y);
  84
  85                         input_report_key(imon->idev, BTN_LEFT,
  86                                          (imon->bits & 0x00010000) != 0);
  87                         input_report_key(imon->idev, BTN_RIGHT,
  88                                          (imon->bits & 0x00040000) != 0);
  89                         input_sync(imon->idev);
  90                         return;
  91                 }
  92         }
  93
  94         rc_keydown(dev, RC_PROTO_IMON, imon->bits, 0);
  95 }
  96
  97 /**
  98  * ir_imon_decode() - Decode one iMON pulse or space
  99  * @dev:        the struct rc_dev descriptor of the device
 100  * @ev:         the struct ir_raw_event descriptor of the pulse/space
 101  *
 102  * This function returns -EINVAL if the pulse violates the state machine
 103  */
 104 static int ir_imon_decode(struct rc_dev *dev, struct ir_raw_event ev)
 105 {
 106         struct imon_dec *data = &dev->raw->imon;
 107
 108         if (!is_timing_event(ev)) {
 109                 if (ev.reset)
 110                         data->state = STATE_INACTIVE;
 111                 return 0;
 112         }
 113
 114         dev_dbg(&dev->dev,
 115                 "iMON decode started at state %d bitno %d (%uus %s)\n",
 116                 data->state, data->count, TO_US(ev.duration),
 117                 TO_STR(ev.pulse));
 118
 119         /*
 120          * Since iMON protocol is a series of bits, if at any point
 121          * we encounter an error, make sure that any remaining bits
 122          * aren't parsed as a scancode made up of less bits.
 123          *
 124          * Note that if the stick is held, then the remote repeats
 125          * the scancode with about 12ms between them. So, make sure
 126          * we have at least 10ms of space after an error. That way,
 127          * we're at a new scancode.
 128          */
 129         if (data->state == STATE_ERROR) {
 130                 if (!ev.pulse && ev.duration > MS_TO_NS(10))
 131                         data->state = STATE_INACTIVE;
 132                 return 0;
 133         }
 134
 135         for (;;) {
 136                 if (!geq_margin(ev.duration, IMON_UNIT, IMON_UNIT / 2))
 137                         return 0;
 138
 139                 decrease_duration(&ev, IMON_UNIT);
 140
 141                 switch (data->state) {
 142                 case STATE_INACTIVE:
 143                         if (ev.pulse) {
 144                                 data->state = STATE_BIT_CHK;
 145                                 data->bits = 0;
 146                                 data->count = IMON_BITS;
 147                         }
 148                         break;
 149                 case STATE_BIT_CHK:
 150                         if (IMON_CHKBITS & BIT(data->count))
 151                                 data->last_chk = ev.pulse;
 152                         else if (ev.pulse)
 153                                 goto err_out;
 154                         data->state = STATE_BIT_START;
 155                         break;
 156                 case STATE_BIT_START:
 157                         data->bits <<= 1;
 158                         if (!ev.pulse)
 159                                 data->bits |= 1;
 160
 161                         if (IMON_CHKBITS & BIT(data->count)) {
 162                                 if (data->last_chk != !(data->bits & 3))
 163                                         goto err_out;
 164                         }
 165
 166                         if (!data->count--)
 167                                 data->state = STATE_FINISHED;
 168                         else
 169                                 data->state = STATE_BIT_CHK;
 170                         break;
 171                 case STATE_FINISHED:
 172                         if (ev.pulse)
 173                                 goto err_out;
 174                         ir_imon_decode_scancode(dev);
 175                         data->state = STATE_INACTIVE;
 176                         break;
 177                 }
 178         }
 179
 180 err_out:
 181         dev_dbg(&dev->dev,
 182                 "iMON decode failed at state %d bitno %d (%uus %s)\n",
 183                 data->state, data->count, TO_US(ev.duration),
 184                 TO_STR(ev.pulse));
 185
 186         data->state = STATE_ERROR;
 187
 188         return -EINVAL;
 189 }
 190
 191 /**
 192  * ir_imon_encode() - Encode a scancode as a stream of raw events
 193  *
 194  * @protocol:   protocol to encode
 195  * @scancode:   scancode to encode
 196  * @events:     array of raw ir events to write into
 197  * @max:        maximum size of @events
 198  *
 199  * Returns:     The number of events written.
 200  *              -ENOBUFS if there isn't enough space in the array to fit the
 201  *              encoding. In this case all @max events will have been written.
 202  */
 203 static int ir_imon_encode(enum rc_proto protocol, u32 scancode,
 204                           struct ir_raw_event *events, unsigned int max)
 205 {
 206         struct ir_raw_event *e = events;
 207         int i, pulse;
 208
 209         if (!max--)
 210                 return -ENOBUFS;
 211         init_ir_raw_event_duration(e, 1, IMON_UNIT);
 212
 213         for (i = IMON_BITS; i >= 0; i--) {
 214                 if (BIT(i) & IMON_CHKBITS)
 215                         pulse = !(scancode & (BIT(i) | BIT(i + 1)));
 216                 else
 217                         pulse = 0;
 218
 219                 if (pulse == e->pulse) {
 220                         e->duration += IMON_UNIT;
 221                 } else {
 222                         if (!max--)
 223                                 return -ENOBUFS;
 224                         init_ir_raw_event_duration(++e, pulse, IMON_UNIT);
 225                 }
 226
 227                 pulse = !(scancode & BIT(i));
 228
 229                 if (pulse == e->pulse) {
 230                         e->duration += IMON_UNIT;
 231                 } else {
 232                         if (!max--)
 233                                 return -ENOBUFS;
 234                         init_ir_raw_event_duration(++e, pulse, IMON_UNIT);
 235                 }
 236         }
 237
 238         if (e->pulse)
 239                 e++;
 240
 241         return e - events;
 242 }
 243
 244 static int ir_imon_register(struct rc_dev *dev)
 245 {
 246         struct input_dev *idev;
 247         struct imon_dec *imon = &dev->raw->imon;
 248         int ret;
 249
 250         idev = input_allocate_device();
 251         if (!idev)
 252                 return -ENOMEM;
 253
 254         snprintf(imon->name, sizeof(imon->name),
 255                  "iMON PAD Stick (%s)", dev->device_name);
 256         idev->name = imon->name;
 257         idev->phys = dev->input_phys;
 258
 259         /* Mouse bits */
 260         set_bit(EV_REL, idev->evbit);
 261         set_bit(EV_KEY, idev->evbit);
 262         set_bit(REL_X, idev->relbit);
 263         set_bit(REL_Y, idev->relbit);
 264         set_bit(BTN_LEFT, idev->keybit);
 265         set_bit(BTN_RIGHT, idev->keybit);
 266
 267         /* Report scancodes too */
 268         set_bit(EV_MSC, idev->evbit);
 269         set_bit(MSC_SCAN, idev->mscbit);
 270
 271         input_set_drvdata(idev, imon);
 272
 273         ret = input_register_device(idev);
 274         if (ret < 0) {
 275                 input_free_device(idev);
 276                 return -EIO;
 277         }
 278
 279         imon->idev = idev;
 280         imon->stick_keyboard = false;
 281
 282         return 0;
 283 }
 284
 285 static int ir_imon_unregister(struct rc_dev *dev)
 286 {
 287         struct imon_dec *imon = &dev->raw->imon;
 288
 289         input_unregister_device(imon->idev);
 290         imon->idev = NULL;
 291
 292         return 0;
 293 }
 294
 295 static struct ir_raw_handler imon_handler = {
 296         .protocols      = RC_PROTO_BIT_IMON,
 297         .decode         = ir_imon_decode,
 298         .encode         = ir_imon_encode,
 299         .carrier        = 38000,
 300         .raw_register   = ir_imon_register,
 301         .raw_unregister = ir_imon_unregister,
 302         .min_timeout    = IMON_UNIT * IMON_BITS * 2,
 303 };
 304
 305 static int __init ir_imon_decode_init(void)
 306 {
 307         ir_raw_handler_register(&imon_handler);
 308
 309         pr_info("IR iMON protocol handler initialized\n");
 310         return 0;
 311 }
 312
 313 static void __exit ir_imon_decode_exit(void)
 314 {
 315         ir_raw_handler_unregister(&imon_handler);
 316 }
 317
 318 module_init(ir_imon_decode_init);
 319 module_exit(ir_imon_decode_exit);
 320
 321 MODULE_LICENSE("GPL");
 322 MODULE_AUTHOR("Sean Young <sean@mess.org>");
 323 MODULE_DESCRIPTION("iMON IR protocol decoder");