1 /* ir-rc6-decoder.c - A decoder for the RC6 IR protocol 2 * 3 * Copyright (C) 2010 by David Härdeman <david@hardeman.nu> 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 "rc-core-priv.h" 16 #include <linux/module.h> 17 18 /* 19 * This decoder currently supports: 20 * RC6-0-16 (standard toggle bit in header) 21 * RC6-6A-20 (no toggle bit) 22 * RC6-6A-24 (no toggle bit) 23 * RC6-6A-32 (MCE version with toggle bit in body) 24 */ 25 26 #define RC6_UNIT 444444 /* nanosecs */ 27 #define RC6_HEADER_NBITS 4 /* not including toggle bit */ 28 #define RC6_0_NBITS 16 29 #define RC6_6A_32_NBITS 32 30 #define RC6_6A_NBITS 128 /* Variable 8..128 */ 31 #define RC6_PREFIX_PULSE (6 * RC6_UNIT) 32 #define RC6_PREFIX_SPACE (2 * RC6_UNIT) 33 #define RC6_BIT_START (1 * RC6_UNIT) 34 #define RC6_BIT_END (1 * RC6_UNIT) 35 #define RC6_TOGGLE_START (2 * RC6_UNIT) 36 #define RC6_TOGGLE_END (2 * RC6_UNIT) 37 #define RC6_SUFFIX_SPACE (6 * RC6_UNIT) 38 #define RC6_MODE_MASK 0x07 /* for the header bits */ 39 #define RC6_STARTBIT_MASK 0x08 /* for the header bits */ 40 #define RC6_6A_MCE_TOGGLE_MASK 0x8000 /* for the body bits */ 41 #define RC6_6A_LCC_MASK 0xffff0000 /* RC6-6A-32 long customer code mask */ 42 #define RC6_6A_MCE_CC 0x800f0000 /* MCE customer code */ 43 #ifndef CHAR_BIT 44 #define CHAR_BIT 8 /* Normally in <limits.h> */ 45 #endif 46 47 enum rc6_mode { 48 RC6_MODE_0, 49 RC6_MODE_6A, 50 RC6_MODE_UNKNOWN, 51 }; 52 53 enum rc6_state { 54 STATE_INACTIVE, 55 STATE_PREFIX_SPACE, 56 STATE_HEADER_BIT_START, 57 STATE_HEADER_BIT_END, 58 STATE_TOGGLE_START, 59 STATE_TOGGLE_END, 60 STATE_BODY_BIT_START, 61 STATE_BODY_BIT_END, 62 STATE_FINISHED, 63 }; 64 65 static enum rc6_mode rc6_mode(struct rc6_dec *data) 66 { 67 switch (data->header & RC6_MODE_MASK) { 68 case 0: 69 return RC6_MODE_0; 70 case 6: 71 if (!data->toggle) 72 return RC6_MODE_6A; 73 /* fall through */ 74 default: 75 return RC6_MODE_UNKNOWN; 76 } 77 } 78 79 /** 80 * ir_rc6_decode() - Decode one RC6 pulse or space 81 * @dev: the struct rc_dev descriptor of the device 82 * @ev: the struct ir_raw_event descriptor of the pulse/space 83 * 84 * This function returns -EINVAL if the pulse violates the state machine 85 */ 86 static int ir_rc6_decode(struct rc_dev *dev, struct ir_raw_event ev) 87 { 88 struct rc6_dec *data = &dev->raw->rc6; 89 u32 scancode; 90 u8 toggle; 91 92 if (!(dev->raw->enabled_protocols & 93 (RC_BIT_RC6_0 | RC_BIT_RC6_6A_20 | RC_BIT_RC6_6A_24 | 94 RC_BIT_RC6_6A_32 | RC_BIT_RC6_MCE))) 95 return 0; 96 97 if (!is_timing_event(ev)) { 98 if (ev.reset) 99 data->state = STATE_INACTIVE; 100 return 0; 101 } 102 103 if (!geq_margin(ev.duration, RC6_UNIT, RC6_UNIT / 2)) 104 goto out; 105 106 again: 107 IR_dprintk(2, "RC6 decode started at state %i (%uus %s)\n", 108 data->state, TO_US(ev.duration), TO_STR(ev.pulse)); 109 110 if (!geq_margin(ev.duration, RC6_UNIT, RC6_UNIT / 2)) 111 return 0; 112 113 switch (data->state) { 114 115 case STATE_INACTIVE: 116 if (!ev.pulse) 117 break; 118 119 /* Note: larger margin on first pulse since each RC6_UNIT 120 is quite short and some hardware takes some time to 121 adjust to the signal */ 122 if (!eq_margin(ev.duration, RC6_PREFIX_PULSE, RC6_UNIT)) 123 break; 124 125 data->state = STATE_PREFIX_SPACE; 126 data->count = 0; 127 return 0; 128 129 case STATE_PREFIX_SPACE: 130 if (ev.pulse) 131 break; 132 133 if (!eq_margin(ev.duration, RC6_PREFIX_SPACE, RC6_UNIT / 2)) 134 break; 135 136 data->state = STATE_HEADER_BIT_START; 137 data->header = 0; 138 return 0; 139 140 case STATE_HEADER_BIT_START: 141 if (!eq_margin(ev.duration, RC6_BIT_START, RC6_UNIT / 2)) 142 break; 143 144 data->header <<= 1; 145 if (ev.pulse) 146 data->header |= 1; 147 data->count++; 148 data->state = STATE_HEADER_BIT_END; 149 return 0; 150 151 case STATE_HEADER_BIT_END: 152 if (!is_transition(&ev, &dev->raw->prev_ev)) 153 break; 154 155 if (data->count == RC6_HEADER_NBITS) 156 data->state = STATE_TOGGLE_START; 157 else 158 data->state = STATE_HEADER_BIT_START; 159 160 decrease_duration(&ev, RC6_BIT_END); 161 goto again; 162 163 case STATE_TOGGLE_START: 164 if (!eq_margin(ev.duration, RC6_TOGGLE_START, RC6_UNIT / 2)) 165 break; 166 167 data->toggle = ev.pulse; 168 data->state = STATE_TOGGLE_END; 169 return 0; 170 171 case STATE_TOGGLE_END: 172 if (!is_transition(&ev, &dev->raw->prev_ev) || 173 !geq_margin(ev.duration, RC6_TOGGLE_END, RC6_UNIT / 2)) 174 break; 175 176 if (!(data->header & RC6_STARTBIT_MASK)) { 177 IR_dprintk(1, "RC6 invalid start bit\n"); 178 break; 179 } 180 181 data->state = STATE_BODY_BIT_START; 182 decrease_duration(&ev, RC6_TOGGLE_END); 183 data->count = 0; 184 data->body = 0; 185 186 switch (rc6_mode(data)) { 187 case RC6_MODE_0: 188 data->wanted_bits = RC6_0_NBITS; 189 break; 190 case RC6_MODE_6A: 191 data->wanted_bits = RC6_6A_NBITS; 192 break; 193 default: 194 IR_dprintk(1, "RC6 unknown mode\n"); 195 goto out; 196 } 197 goto again; 198 199 case STATE_BODY_BIT_START: 200 if (eq_margin(ev.duration, RC6_BIT_START, RC6_UNIT / 2)) { 201 /* Discard LSB's that won't fit in data->body */ 202 if (data->count++ < CHAR_BIT * sizeof data->body) { 203 data->body <<= 1; 204 if (ev.pulse) 205 data->body |= 1; 206 } 207 data->state = STATE_BODY_BIT_END; 208 return 0; 209 } else if (RC6_MODE_6A == rc6_mode(data) && !ev.pulse && 210 geq_margin(ev.duration, RC6_SUFFIX_SPACE, RC6_UNIT / 2)) { 211 data->state = STATE_FINISHED; 212 goto again; 213 } 214 break; 215 216 case STATE_BODY_BIT_END: 217 if (!is_transition(&ev, &dev->raw->prev_ev)) 218 break; 219 220 if (data->count == data->wanted_bits) 221 data->state = STATE_FINISHED; 222 else 223 data->state = STATE_BODY_BIT_START; 224 225 decrease_duration(&ev, RC6_BIT_END); 226 goto again; 227 228 case STATE_FINISHED: 229 if (ev.pulse) 230 break; 231 232 switch (rc6_mode(data)) { 233 case RC6_MODE_0: 234 scancode = data->body; 235 toggle = data->toggle; 236 IR_dprintk(1, "RC6(0) scancode 0x%04x (toggle: %u)\n", 237 scancode, toggle); 238 break; 239 case RC6_MODE_6A: 240 if (data->count > CHAR_BIT * sizeof data->body) { 241 IR_dprintk(1, "RC6 too many (%u) data bits\n", 242 data->count); 243 goto out; 244 } 245 246 scancode = data->body; 247 if (data->count == RC6_6A_32_NBITS && 248 (scancode & RC6_6A_LCC_MASK) == RC6_6A_MCE_CC) { 249 /* MCE RC */ 250 toggle = (scancode & RC6_6A_MCE_TOGGLE_MASK) ? 1 : 0; 251 scancode &= ~RC6_6A_MCE_TOGGLE_MASK; 252 } else { 253 toggle = 0; 254 } 255 IR_dprintk(1, "RC6(6A) scancode 0x%08x (toggle: %u)\n", 256 scancode, toggle); 257 break; 258 default: 259 IR_dprintk(1, "RC6 unknown mode\n"); 260 goto out; 261 } 262 263 rc_keydown(dev, scancode, toggle); 264 data->state = STATE_INACTIVE; 265 return 0; 266 } 267 268 out: 269 IR_dprintk(1, "RC6 decode failed at state %i (%uus %s)\n", 270 data->state, TO_US(ev.duration), TO_STR(ev.pulse)); 271 data->state = STATE_INACTIVE; 272 return -EINVAL; 273 } 274 275 static struct ir_raw_handler rc6_handler = { 276 .protocols = RC_BIT_RC6_0 | RC_BIT_RC6_6A_20 | 277 RC_BIT_RC6_6A_24 | RC_BIT_RC6_6A_32 | 278 RC_BIT_RC6_MCE, 279 .decode = ir_rc6_decode, 280 }; 281 282 static int __init ir_rc6_decode_init(void) 283 { 284 ir_raw_handler_register(&rc6_handler); 285 286 printk(KERN_INFO "IR RC6 protocol handler initialized\n"); 287 return 0; 288 } 289 290 static void __exit ir_rc6_decode_exit(void) 291 { 292 ir_raw_handler_unregister(&rc6_handler); 293 } 294 295 module_init(ir_rc6_decode_init); 296 module_exit(ir_rc6_decode_exit); 297 298 MODULE_LICENSE("GPL"); 299 MODULE_AUTHOR("David Härdeman <david@hardeman.nu>"); 300 MODULE_DESCRIPTION("RC6 IR protocol decoder"); 301