1 /* ir-nec-decoder.c - handle NEC IR Pulse/Space protocol 2 * 3 * Copyright (C) 2010 by Mauro Carvalho Chehab 4 * 5 * This program is free software; you can redistribute it and/or modify 6 * it under the terms of the GNU General Public License as published by 7 * the Free Software Foundation version 2 of the License. 8 * 9 * This program is distributed in the hope that it will be useful, 10 * but WITHOUT ANY WARRANTY; without even the implied warranty of 11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 12 * GNU General Public License for more details. 13 */ 14 15 #include <linux/bitrev.h> 16 #include <linux/module.h> 17 #include "rc-core-priv.h" 18 19 #define NEC_NBITS 32 20 #define NEC_UNIT 562500 /* ns */ 21 #define NEC_HEADER_PULSE (16 * NEC_UNIT) 22 #define NECX_HEADER_PULSE (8 * NEC_UNIT) /* Less common NEC variant */ 23 #define NEC_HEADER_SPACE (8 * NEC_UNIT) 24 #define NEC_REPEAT_SPACE (4 * NEC_UNIT) 25 #define NEC_BIT_PULSE (1 * NEC_UNIT) 26 #define NEC_BIT_0_SPACE (1 * NEC_UNIT) 27 #define NEC_BIT_1_SPACE (3 * NEC_UNIT) 28 #define NEC_TRAILER_PULSE (1 * NEC_UNIT) 29 #define NEC_TRAILER_SPACE (10 * NEC_UNIT) /* even longer in reality */ 30 #define NECX_REPEAT_BITS 1 31 32 enum nec_state { 33 STATE_INACTIVE, 34 STATE_HEADER_SPACE, 35 STATE_BIT_PULSE, 36 STATE_BIT_SPACE, 37 STATE_TRAILER_PULSE, 38 STATE_TRAILER_SPACE, 39 }; 40 41 /** 42 * ir_nec_decode() - Decode one NEC pulse or space 43 * @dev: the struct rc_dev descriptor of the device 44 * @duration: the struct ir_raw_event descriptor of the pulse/space 45 * 46 * This function returns -EINVAL if the pulse violates the state machine 47 */ 48 static int ir_nec_decode(struct rc_dev *dev, struct ir_raw_event ev) 49 { 50 struct nec_dec *data = &dev->raw->nec; 51 u32 scancode; 52 enum rc_proto rc_proto; 53 u8 address, not_address, command, not_command; 54 55 if (!is_timing_event(ev)) { 56 if (ev.reset) 57 data->state = STATE_INACTIVE; 58 return 0; 59 } 60 61 IR_dprintk(2, "NEC decode started at state %d (%uus %s)\n", 62 data->state, TO_US(ev.duration), TO_STR(ev.pulse)); 63 64 switch (data->state) { 65 66 case STATE_INACTIVE: 67 if (!ev.pulse) 68 break; 69 70 if (eq_margin(ev.duration, NEC_HEADER_PULSE, NEC_UNIT * 2)) { 71 data->is_nec_x = false; 72 data->necx_repeat = false; 73 } else if (eq_margin(ev.duration, NECX_HEADER_PULSE, NEC_UNIT / 2)) 74 data->is_nec_x = true; 75 else 76 break; 77 78 data->count = 0; 79 data->state = STATE_HEADER_SPACE; 80 return 0; 81 82 case STATE_HEADER_SPACE: 83 if (ev.pulse) 84 break; 85 86 if (eq_margin(ev.duration, NEC_HEADER_SPACE, NEC_UNIT)) { 87 data->state = STATE_BIT_PULSE; 88 return 0; 89 } else if (eq_margin(ev.duration, NEC_REPEAT_SPACE, NEC_UNIT / 2)) { 90 data->state = STATE_TRAILER_PULSE; 91 return 0; 92 } 93 94 break; 95 96 case STATE_BIT_PULSE: 97 if (!ev.pulse) 98 break; 99 100 if (!eq_margin(ev.duration, NEC_BIT_PULSE, NEC_UNIT / 2)) 101 break; 102 103 data->state = STATE_BIT_SPACE; 104 return 0; 105 106 case STATE_BIT_SPACE: 107 if (ev.pulse) 108 break; 109 110 if (data->necx_repeat && data->count == NECX_REPEAT_BITS && 111 geq_margin(ev.duration, 112 NEC_TRAILER_SPACE, NEC_UNIT / 2)) { 113 IR_dprintk(1, "Repeat last key\n"); 114 rc_repeat(dev); 115 data->state = STATE_INACTIVE; 116 return 0; 117 118 } else if (data->count > NECX_REPEAT_BITS) 119 data->necx_repeat = false; 120 121 data->bits <<= 1; 122 if (eq_margin(ev.duration, NEC_BIT_1_SPACE, NEC_UNIT / 2)) 123 data->bits |= 1; 124 else if (!eq_margin(ev.duration, NEC_BIT_0_SPACE, NEC_UNIT / 2)) 125 break; 126 data->count++; 127 128 if (data->count == NEC_NBITS) 129 data->state = STATE_TRAILER_PULSE; 130 else 131 data->state = STATE_BIT_PULSE; 132 133 return 0; 134 135 case STATE_TRAILER_PULSE: 136 if (!ev.pulse) 137 break; 138 139 if (!eq_margin(ev.duration, NEC_TRAILER_PULSE, NEC_UNIT / 2)) 140 break; 141 142 data->state = STATE_TRAILER_SPACE; 143 return 0; 144 145 case STATE_TRAILER_SPACE: 146 if (ev.pulse) 147 break; 148 149 if (!geq_margin(ev.duration, NEC_TRAILER_SPACE, NEC_UNIT / 2)) 150 break; 151 152 if (data->count == NEC_NBITS) { 153 address = bitrev8((data->bits >> 24) & 0xff); 154 not_address = bitrev8((data->bits >> 16) & 0xff); 155 command = bitrev8((data->bits >> 8) & 0xff); 156 not_command = bitrev8((data->bits >> 0) & 0xff); 157 158 scancode = ir_nec_bytes_to_scancode(address, 159 not_address, 160 command, 161 not_command, 162 &rc_proto); 163 164 if (data->is_nec_x) 165 data->necx_repeat = true; 166 167 rc_keydown(dev, rc_proto, scancode, 0); 168 } else { 169 rc_repeat(dev); 170 } 171 172 data->state = STATE_INACTIVE; 173 return 0; 174 } 175 176 IR_dprintk(1, "NEC decode failed at count %d state %d (%uus %s)\n", 177 data->count, data->state, TO_US(ev.duration), TO_STR(ev.pulse)); 178 data->state = STATE_INACTIVE; 179 return -EINVAL; 180 } 181 182 /** 183 * ir_nec_scancode_to_raw() - encode an NEC scancode ready for modulation. 184 * @protocol: specific protocol to use 185 * @scancode: a single NEC scancode. 186 * @raw: raw data to be modulated. 187 */ 188 static u32 ir_nec_scancode_to_raw(enum rc_proto protocol, u32 scancode) 189 { 190 unsigned int addr, addr_inv, data, data_inv; 191 192 data = scancode & 0xff; 193 194 if (protocol == RC_PROTO_NEC32) { 195 /* 32-bit NEC (used by Apple and TiVo remotes) */ 196 /* scan encoding: aaAAddDD */ 197 addr_inv = (scancode >> 24) & 0xff; 198 addr = (scancode >> 16) & 0xff; 199 data_inv = (scancode >> 8) & 0xff; 200 } else if (protocol == RC_PROTO_NECX) { 201 /* Extended NEC */ 202 /* scan encoding AAaaDD */ 203 addr = (scancode >> 16) & 0xff; 204 addr_inv = (scancode >> 8) & 0xff; 205 data_inv = data ^ 0xff; 206 } else { 207 /* Normal NEC */ 208 /* scan encoding: AADD */ 209 addr = (scancode >> 8) & 0xff; 210 addr_inv = addr ^ 0xff; 211 data_inv = data ^ 0xff; 212 } 213 214 /* raw encoding: ddDDaaAA */ 215 return data_inv << 24 | 216 data << 16 | 217 addr_inv << 8 | 218 addr; 219 } 220 221 static const struct ir_raw_timings_pd ir_nec_timings = { 222 .header_pulse = NEC_HEADER_PULSE, 223 .header_space = NEC_HEADER_SPACE, 224 .bit_pulse = NEC_BIT_PULSE, 225 .bit_space[0] = NEC_BIT_0_SPACE, 226 .bit_space[1] = NEC_BIT_1_SPACE, 227 .trailer_pulse = NEC_TRAILER_PULSE, 228 .trailer_space = NEC_TRAILER_SPACE, 229 .msb_first = 0, 230 }; 231 232 /** 233 * ir_nec_encode() - Encode a scancode as a stream of raw events 234 * 235 * @protocol: protocol to encode 236 * @scancode: scancode to encode 237 * @events: array of raw ir events to write into 238 * @max: maximum size of @events 239 * 240 * Returns: The number of events written. 241 * -ENOBUFS if there isn't enough space in the array to fit the 242 * encoding. In this case all @max events will have been written. 243 */ 244 static int ir_nec_encode(enum rc_proto protocol, u32 scancode, 245 struct ir_raw_event *events, unsigned int max) 246 { 247 struct ir_raw_event *e = events; 248 int ret; 249 u32 raw; 250 251 /* Convert a NEC scancode to raw NEC data */ 252 raw = ir_nec_scancode_to_raw(protocol, scancode); 253 254 /* Modulate the raw data using a pulse distance modulation */ 255 ret = ir_raw_gen_pd(&e, max, &ir_nec_timings, NEC_NBITS, raw); 256 if (ret < 0) 257 return ret; 258 259 return e - events; 260 } 261 262 static struct ir_raw_handler nec_handler = { 263 .protocols = RC_PROTO_BIT_NEC | RC_PROTO_BIT_NECX | 264 RC_PROTO_BIT_NEC32, 265 .decode = ir_nec_decode, 266 .encode = ir_nec_encode, 267 }; 268 269 static int __init ir_nec_decode_init(void) 270 { 271 ir_raw_handler_register(&nec_handler); 272 273 printk(KERN_INFO "IR NEC protocol handler initialized\n"); 274 return 0; 275 } 276 277 static void __exit ir_nec_decode_exit(void) 278 { 279 ir_raw_handler_unregister(&nec_handler); 280 } 281 282 module_init(ir_nec_decode_init); 283 module_exit(ir_nec_decode_exit); 284 285 MODULE_LICENSE("GPL"); 286 MODULE_AUTHOR("Mauro Carvalho Chehab"); 287 MODULE_AUTHOR("Red Hat Inc. (http://www.redhat.com)"); 288 MODULE_DESCRIPTION("NEC IR protocol decoder"); 289