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1// SPDX-License-Identifier: GPL-2.02// ir-nec-decoder.c - handle NEC IR Pulse/Space protocol3//4// Copyright (C) 2010 by Mauro Carvalho Chehab5 6#include <linux/bitrev.h>7#include <linux/module.h>8#include "rc-core-priv.h"9 10#define NEC_NBITS 3211#define NEC_UNIT 563 /* us */12#define NEC_HEADER_PULSE (16 * NEC_UNIT)13#define NECX_HEADER_PULSE (8 * NEC_UNIT) /* Less common NEC variant */14#define NEC_HEADER_SPACE (8 * NEC_UNIT)15#define NEC_REPEAT_SPACE (4 * NEC_UNIT)16#define NEC_BIT_PULSE (1 * NEC_UNIT)17#define NEC_BIT_0_SPACE (1 * NEC_UNIT)18#define NEC_BIT_1_SPACE (3 * NEC_UNIT)19#define NEC_TRAILER_PULSE (1 * NEC_UNIT)20#define NEC_TRAILER_SPACE (10 * NEC_UNIT) /* even longer in reality */21#define NECX_REPEAT_BITS 122 23enum nec_state {24 STATE_INACTIVE,25 STATE_HEADER_SPACE,26 STATE_BIT_PULSE,27 STATE_BIT_SPACE,28 STATE_TRAILER_PULSE,29 STATE_TRAILER_SPACE,30};31 32/**33 * ir_nec_decode() - Decode one NEC pulse or space34 * @dev: the struct rc_dev descriptor of the device35 * @ev: the struct ir_raw_event descriptor of the pulse/space36 *37 * This function returns -EINVAL if the pulse violates the state machine38 */39static int ir_nec_decode(struct rc_dev *dev, struct ir_raw_event ev)40{41 struct nec_dec *data = &dev->raw->nec;42 u32 scancode;43 enum rc_proto rc_proto;44 u8 address, not_address, command, not_command;45 46 if (!is_timing_event(ev)) {47 if (ev.overflow)48 data->state = STATE_INACTIVE;49 return 0;50 }51 52 dev_dbg(&dev->dev, "NEC decode started at state %d (%uus %s)\n",53 data->state, ev.duration, TO_STR(ev.pulse));54 55 switch (data->state) {56 57 case STATE_INACTIVE:58 if (!ev.pulse)59 break;60 61 if (eq_margin(ev.duration, NEC_HEADER_PULSE, NEC_UNIT * 2)) {62 data->is_nec_x = false;63 data->necx_repeat = false;64 } else if (eq_margin(ev.duration, NECX_HEADER_PULSE, NEC_UNIT / 2))65 data->is_nec_x = true;66 else67 break;68 69 data->count = 0;70 data->state = STATE_HEADER_SPACE;71 return 0;72 73 case STATE_HEADER_SPACE:74 if (ev.pulse)75 break;76 77 if (eq_margin(ev.duration, NEC_HEADER_SPACE, NEC_UNIT)) {78 data->state = STATE_BIT_PULSE;79 return 0;80 } else if (eq_margin(ev.duration, NEC_REPEAT_SPACE, NEC_UNIT / 2)) {81 data->state = STATE_TRAILER_PULSE;82 return 0;83 }84 85 break;86 87 case STATE_BIT_PULSE:88 if (!ev.pulse)89 break;90 91 if (!eq_margin(ev.duration, NEC_BIT_PULSE, NEC_UNIT / 2))92 break;93 94 data->state = STATE_BIT_SPACE;95 return 0;96 97 case STATE_BIT_SPACE:98 if (ev.pulse)99 break;100 101 if (data->necx_repeat && data->count == NECX_REPEAT_BITS &&102 geq_margin(ev.duration, NEC_TRAILER_SPACE, NEC_UNIT / 2)) {103 dev_dbg(&dev->dev, "Repeat last key\n");104 rc_repeat(dev);105 data->state = STATE_INACTIVE;106 return 0;107 } else if (data->count > NECX_REPEAT_BITS)108 data->necx_repeat = false;109 110 data->bits <<= 1;111 if (eq_margin(ev.duration, NEC_BIT_1_SPACE, NEC_UNIT / 2))112 data->bits |= 1;113 else if (!eq_margin(ev.duration, NEC_BIT_0_SPACE, NEC_UNIT / 2))114 break;115 data->count++;116 117 if (data->count == NEC_NBITS)118 data->state = STATE_TRAILER_PULSE;119 else120 data->state = STATE_BIT_PULSE;121 122 return 0;123 124 case STATE_TRAILER_PULSE:125 if (!ev.pulse)126 break;127 128 if (!eq_margin(ev.duration, NEC_TRAILER_PULSE, NEC_UNIT / 2))129 break;130 131 data->state = STATE_TRAILER_SPACE;132 return 0;133 134 case STATE_TRAILER_SPACE:135 if (ev.pulse)136 break;137 138 if (!geq_margin(ev.duration, NEC_TRAILER_SPACE, NEC_UNIT / 2))139 break;140 141 if (data->count == NEC_NBITS) {142 address = bitrev8((data->bits >> 24) & 0xff);143 not_address = bitrev8((data->bits >> 16) & 0xff);144 command = bitrev8((data->bits >> 8) & 0xff);145 not_command = bitrev8((data->bits >> 0) & 0xff);146 147 scancode = ir_nec_bytes_to_scancode(address,148 not_address,149 command,150 not_command,151 &rc_proto);152 153 if (data->is_nec_x)154 data->necx_repeat = true;155 156 rc_keydown(dev, rc_proto, scancode, 0);157 } else {158 rc_repeat(dev);159 }160 161 data->state = STATE_INACTIVE;162 return 0;163 }164 165 dev_dbg(&dev->dev, "NEC decode failed at count %d state %d (%uus %s)\n",166 data->count, data->state, ev.duration, TO_STR(ev.pulse));167 data->state = STATE_INACTIVE;168 return -EINVAL;169}170 171/**172 * ir_nec_scancode_to_raw() - encode an NEC scancode ready for modulation.173 * @protocol: specific protocol to use174 * @scancode: a single NEC scancode.175 */176static u32 ir_nec_scancode_to_raw(enum rc_proto protocol, u32 scancode)177{178 unsigned int addr, addr_inv, data, data_inv;179 180 data = scancode & 0xff;181 182 if (protocol == RC_PROTO_NEC32) {183 /* 32-bit NEC (used by Apple and TiVo remotes) */184 /* scan encoding: aaAAddDD */185 addr_inv = (scancode >> 24) & 0xff;186 addr = (scancode >> 16) & 0xff;187 data_inv = (scancode >> 8) & 0xff;188 } else if (protocol == RC_PROTO_NECX) {189 /* Extended NEC */190 /* scan encoding AAaaDD */191 addr = (scancode >> 16) & 0xff;192 addr_inv = (scancode >> 8) & 0xff;193 data_inv = data ^ 0xff;194 } else {195 /* Normal NEC */196 /* scan encoding: AADD */197 addr = (scancode >> 8) & 0xff;198 addr_inv = addr ^ 0xff;199 data_inv = data ^ 0xff;200 }201 202 /* raw encoding: ddDDaaAA */203 return data_inv << 24 |204 data << 16 |205 addr_inv << 8 |206 addr;207}208 209static const struct ir_raw_timings_pd ir_nec_timings = {210 .header_pulse = NEC_HEADER_PULSE,211 .header_space = NEC_HEADER_SPACE,212 .bit_pulse = NEC_BIT_PULSE,213 .bit_space[0] = NEC_BIT_0_SPACE,214 .bit_space[1] = NEC_BIT_1_SPACE,215 .trailer_pulse = NEC_TRAILER_PULSE,216 .trailer_space = NEC_TRAILER_SPACE,217 .msb_first = 0,218};219 220/**221 * ir_nec_encode() - Encode a scancode as a stream of raw events222 *223 * @protocol: protocol to encode224 * @scancode: scancode to encode225 * @events: array of raw ir events to write into226 * @max: maximum size of @events227 *228 * Returns: The number of events written.229 * -ENOBUFS if there isn't enough space in the array to fit the230 * encoding. In this case all @max events will have been written.231 */232static int ir_nec_encode(enum rc_proto protocol, u32 scancode,233 struct ir_raw_event *events, unsigned int max)234{235 struct ir_raw_event *e = events;236 int ret;237 u32 raw;238 239 /* Convert a NEC scancode to raw NEC data */240 raw = ir_nec_scancode_to_raw(protocol, scancode);241 242 /* Modulate the raw data using a pulse distance modulation */243 ret = ir_raw_gen_pd(&e, max, &ir_nec_timings, NEC_NBITS, raw);244 if (ret < 0)245 return ret;246 247 return e - events;248}249 250static struct ir_raw_handler nec_handler = {251 .protocols = RC_PROTO_BIT_NEC | RC_PROTO_BIT_NECX |252 RC_PROTO_BIT_NEC32,253 .decode = ir_nec_decode,254 .encode = ir_nec_encode,255 .carrier = 38000,256 .min_timeout = NEC_TRAILER_SPACE,257};258 259static int __init ir_nec_decode_init(void)260{261 ir_raw_handler_register(&nec_handler);262 263 printk(KERN_INFO "IR NEC protocol handler initialized\n");264 return 0;265}266 267static void __exit ir_nec_decode_exit(void)268{269 ir_raw_handler_unregister(&nec_handler);270}271 272module_init(ir_nec_decode_init);273module_exit(ir_nec_decode_exit);274 275MODULE_LICENSE("GPL v2");276MODULE_AUTHOR("Mauro Carvalho Chehab");277MODULE_AUTHOR("Red Hat Inc. (http://www.redhat.com)");278MODULE_DESCRIPTION("NEC IR protocol decoder");279