268 lines · c
1// SPDX-License-Identifier: GPL-2.0+2// ir-imon-decoder.c - handle iMon protocol3//4// Copyright (C) 2018 by Sean Young <sean@mess.org>5 6#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt7 8#include <linux/module.h>9#include "rc-core-priv.h"10 11#define IMON_UNIT 416 /* us */12#define IMON_BITS 3013#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 then21 * 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 if23 * both the preceding and current bit are zero, else space. IMON_CHKBITS24 * defines which bits are of type check.25 *26 * There is no way to distinguish an incomplete message from one where27 * the lower bits are all set, iow. the last pulse is for the lowest28 * 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 else67 imon->bits = rel_x > 0 ?68 0x2ba515b7 : /* KEY_RIGHT */69 0x29a515b7; /* KEY_LEFT */70 }71 72 if (!imon->stick_keyboard) {73 input_report_rel(dev->input_dev, REL_X, rel_x);74 input_report_rel(dev->input_dev, REL_Y, rel_y);75 76 input_report_key(dev->input_dev, BTN_LEFT,77 (imon->bits & 0x00010000) != 0);78 input_report_key(dev->input_dev, BTN_RIGHT,79 (imon->bits & 0x00040000) != 0);80 }81 }82 83 rc_keydown(dev, RC_PROTO_IMON, imon->bits, 0);84}85 86/**87 * ir_imon_decode() - Decode one iMON pulse or space88 * @dev: the struct rc_dev descriptor of the device89 * @ev: the struct ir_raw_event descriptor of the pulse/space90 *91 * This function returns -EINVAL if the pulse violates the state machine92 */93static int ir_imon_decode(struct rc_dev *dev, struct ir_raw_event ev)94{95 struct imon_dec *data = &dev->raw->imon;96 97 if (!is_timing_event(ev)) {98 if (ev.overflow)99 data->state = STATE_INACTIVE;100 return 0;101 }102 103 dev_dbg(&dev->dev,104 "iMON decode started at state %d bitno %d (%uus %s)\n",105 data->state, data->count, ev.duration, TO_STR(ev.pulse));106 107 /*108 * Since iMON protocol is a series of bits, if at any point109 * we encounter an error, make sure that any remaining bits110 * aren't parsed as a scancode made up of less bits.111 *112 * Note that if the stick is held, then the remote repeats113 * the scancode with about 12ms between them. So, make sure114 * we have at least 10ms of space after an error. That way,115 * we're at a new scancode.116 */117 if (data->state == STATE_ERROR) {118 if (!ev.pulse && ev.duration > MS_TO_US(10))119 data->state = STATE_INACTIVE;120 return 0;121 }122 123 for (;;) {124 if (!geq_margin(ev.duration, IMON_UNIT, IMON_UNIT / 2))125 return 0;126 127 decrease_duration(&ev, IMON_UNIT);128 129 switch (data->state) {130 case STATE_INACTIVE:131 if (ev.pulse) {132 data->state = STATE_BIT_CHK;133 data->bits = 0;134 data->count = IMON_BITS;135 }136 break;137 case STATE_BIT_CHK:138 if (IMON_CHKBITS & BIT(data->count))139 data->last_chk = ev.pulse;140 else if (ev.pulse)141 goto err_out;142 data->state = STATE_BIT_START;143 break;144 case STATE_BIT_START:145 data->bits <<= 1;146 if (!ev.pulse)147 data->bits |= 1;148 149 if (IMON_CHKBITS & BIT(data->count)) {150 if (data->last_chk != !(data->bits & 3))151 goto err_out;152 }153 154 if (!data->count--)155 data->state = STATE_FINISHED;156 else157 data->state = STATE_BIT_CHK;158 break;159 case STATE_FINISHED:160 if (ev.pulse)161 goto err_out;162 ir_imon_decode_scancode(dev);163 data->state = STATE_INACTIVE;164 break;165 }166 }167 168err_out:169 dev_dbg(&dev->dev,170 "iMON decode failed at state %d bitno %d (%uus %s)\n",171 data->state, data->count, ev.duration, TO_STR(ev.pulse));172 173 data->state = STATE_ERROR;174 175 return -EINVAL;176}177 178/**179 * ir_imon_encode() - Encode a scancode as a stream of raw events180 *181 * @protocol: protocol to encode182 * @scancode: scancode to encode183 * @events: array of raw ir events to write into184 * @max: maximum size of @events185 *186 * Returns: The number of events written.187 * -ENOBUFS if there isn't enough space in the array to fit the188 * encoding. In this case all @max events will have been written.189 */190static int ir_imon_encode(enum rc_proto protocol, u32 scancode,191 struct ir_raw_event *events, unsigned int max)192{193 struct ir_raw_event *e = events;194 int i, pulse;195 196 if (!max--)197 return -ENOBUFS;198 init_ir_raw_event_duration(e, 1, IMON_UNIT);199 200 for (i = IMON_BITS; i >= 0; i--) {201 if (BIT(i) & IMON_CHKBITS)202 pulse = !(scancode & (BIT(i) | BIT(i + 1)));203 else204 pulse = 0;205 206 if (pulse == e->pulse) {207 e->duration += IMON_UNIT;208 } else {209 if (!max--)210 return -ENOBUFS;211 init_ir_raw_event_duration(++e, pulse, IMON_UNIT);212 }213 214 pulse = !(scancode & BIT(i));215 216 if (pulse == e->pulse) {217 e->duration += IMON_UNIT;218 } else {219 if (!max--)220 return -ENOBUFS;221 init_ir_raw_event_duration(++e, pulse, IMON_UNIT);222 }223 }224 225 if (e->pulse)226 e++;227 228 return e - events;229}230 231static int ir_imon_register(struct rc_dev *dev)232{233 struct imon_dec *imon = &dev->raw->imon;234 235 imon->stick_keyboard = false;236 237 return 0;238}239 240static struct ir_raw_handler imon_handler = {241 .protocols = RC_PROTO_BIT_IMON,242 .decode = ir_imon_decode,243 .encode = ir_imon_encode,244 .carrier = 38000,245 .raw_register = ir_imon_register,246 .min_timeout = IMON_UNIT * IMON_BITS * 2,247};248 249static int __init ir_imon_decode_init(void)250{251 ir_raw_handler_register(&imon_handler);252 253 pr_info("IR iMON protocol handler initialized\n");254 return 0;255}256 257static void __exit ir_imon_decode_exit(void)258{259 ir_raw_handler_unregister(&imon_handler);260}261 262module_init(ir_imon_decode_init);263module_exit(ir_imon_decode_exit);264 265MODULE_LICENSE("GPL");266MODULE_AUTHOR("Sean Young <sean@mess.org>");267MODULE_DESCRIPTION("iMON IR protocol decoder");268