LXR linux/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 */
  30enum imon_state {
  31        STATE_INACTIVE,
  32        STATE_BIT_CHK,
  33        STATE_BIT_START,
  34        STATE_FINISHED,
  35        STATE_ERROR,
  36};
  37
  38static 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 */
 104static 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
 180err_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 */
 203static 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
 244static 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
 285static 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
 295static 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
 305static 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
 313static void __exit ir_imon_decode_exit(void)
 314{
 315        ir_raw_handler_unregister(&imon_handler);
 316}
 317
 318module_init(ir_imon_decode_init);
 319module_exit(ir_imon_decode_exit);
 320
 321MODULE_LICENSE("GPL");
 322MODULE_AUTHOR("Sean Young <sean@mess.org>");
 323MODULE_DESCRIPTION("iMON IR protocol decoder");
 324