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 & RC_TYPE_RC6)) 93 return 0; 94 95 if (!is_timing_event(ev)) { 96 if (ev.reset) 97 data->state = STATE_INACTIVE; 98 return 0; 99 } 100 101 if (!geq_margin(ev.duration, RC6_UNIT, RC6_UNIT / 2)) 102 goto out; 103 104 again: 105 IR_dprintk(2, "RC6 decode started at state %i (%uus %s)\n", 106 data->state, TO_US(ev.duration), TO_STR(ev.pulse)); 107 108 if (!geq_margin(ev.duration, RC6_UNIT, RC6_UNIT / 2)) 109 return 0; 110 111 switch (data->state) { 112 113 case STATE_INACTIVE: 114 if (!ev.pulse) 115 break; 116 117 /* Note: larger margin on first pulse since each RC6_UNIT 118 is quite short and some hardware takes some time to 119 adjust to the signal */ 120 if (!eq_margin(ev.duration, RC6_PREFIX_PULSE, RC6_UNIT)) 121 break; 122 123 data->state = STATE_PREFIX_SPACE; 124 data->count = 0; 125 return 0; 126 127 case STATE_PREFIX_SPACE: 128 if (ev.pulse) 129 break; 130 131 if (!eq_margin(ev.duration, RC6_PREFIX_SPACE, RC6_UNIT / 2)) 132 break; 133 134 data->state = STATE_HEADER_BIT_START; 135 data->header = 0; 136 return 0; 137 138 case STATE_HEADER_BIT_START: 139 if (!eq_margin(ev.duration, RC6_BIT_START, RC6_UNIT / 2)) 140 break; 141 142 data->header <<= 1; 143 if (ev.pulse) 144 data->header |= 1; 145 data->count++; 146 data->state = STATE_HEADER_BIT_END; 147 return 0; 148 149 case STATE_HEADER_BIT_END: 150 if (!is_transition(&ev, &dev->raw->prev_ev)) 151 break; 152 153 if (data->count == RC6_HEADER_NBITS) 154 data->state = STATE_TOGGLE_START; 155 else 156 data->state = STATE_HEADER_BIT_START; 157 158 decrease_duration(&ev, RC6_BIT_END); 159 goto again; 160 161 case STATE_TOGGLE_START: 162 if (!eq_margin(ev.duration, RC6_TOGGLE_START, RC6_UNIT / 2)) 163 break; 164 165 data->toggle = ev.pulse; 166 data->state = STATE_TOGGLE_END; 167 return 0; 168 169 case STATE_TOGGLE_END: 170 if (!is_transition(&ev, &dev->raw->prev_ev) || 171 !geq_margin(ev.duration, RC6_TOGGLE_END, RC6_UNIT / 2)) 172 break; 173 174 if (!(data->header & RC6_STARTBIT_MASK)) { 175 IR_dprintk(1, "RC6 invalid start bit\n"); 176 break; 177 } 178 179 data->state = STATE_BODY_BIT_START; 180 decrease_duration(&ev, RC6_TOGGLE_END); 181 data->count = 0; 182 data->body = 0; 183 184 switch (rc6_mode(data)) { 185 case RC6_MODE_0: 186 data->wanted_bits = RC6_0_NBITS; 187 break; 188 case RC6_MODE_6A: 189 data->wanted_bits = RC6_6A_NBITS; 190 break; 191 default: 192 IR_dprintk(1, "RC6 unknown mode\n"); 193 goto out; 194 } 195 goto again; 196 197 case STATE_BODY_BIT_START: 198 if (eq_margin(ev.duration, RC6_BIT_START, RC6_UNIT / 2)) { 199 /* Discard LSB's that won't fit in data->body */ 200 if (data->count++ < CHAR_BIT * sizeof data->body) { 201 data->body <<= 1; 202 if (ev.pulse) 203 data->body |= 1; 204 } 205 data->state = STATE_BODY_BIT_END; 206 return 0; 207 } else if (RC6_MODE_6A == rc6_mode(data) && !ev.pulse && 208 geq_margin(ev.duration, RC6_SUFFIX_SPACE, RC6_UNIT / 2)) { 209 data->state = STATE_FINISHED; 210 goto again; 211 } 212 break; 213 214 case STATE_BODY_BIT_END: 215 if (!is_transition(&ev, &dev->raw->prev_ev)) 216 break; 217 218 if (data->count == data->wanted_bits) 219 data->state = STATE_FINISHED; 220 else 221 data->state = STATE_BODY_BIT_START; 222 223 decrease_duration(&ev, RC6_BIT_END); 224 goto again; 225 226 case STATE_FINISHED: 227 if (ev.pulse) 228 break; 229 230 switch (rc6_mode(data)) { 231 case RC6_MODE_0: 232 scancode = data->body; 233 toggle = data->toggle; 234 IR_dprintk(1, "RC6(0) scancode 0x%04x (toggle: %u)\n", 235 scancode, toggle); 236 break; 237 case RC6_MODE_6A: 238 if (data->count > CHAR_BIT * sizeof data->body) { 239 IR_dprintk(1, "RC6 too many (%u) data bits\n", 240 data->count); 241 goto out; 242 } 243 244 scancode = data->body; 245 if (data->count == RC6_6A_32_NBITS && 246 (scancode & RC6_6A_LCC_MASK) == RC6_6A_MCE_CC) { 247 /* MCE RC */ 248 toggle = (scancode & RC6_6A_MCE_TOGGLE_MASK) ? 1 : 0; 249 scancode &= ~RC6_6A_MCE_TOGGLE_MASK; 250 } else { 251 toggle = 0; 252 } 253 IR_dprintk(1, "RC6(6A) scancode 0x%08x (toggle: %u)\n", 254 scancode, toggle); 255 break; 256 default: 257 IR_dprintk(1, "RC6 unknown mode\n"); 258 goto out; 259 } 260 261 rc_keydown(dev, scancode, toggle); 262 data->state = STATE_INACTIVE; 263 return 0; 264 } 265 266 out: 267 IR_dprintk(1, "RC6 decode failed at state %i (%uus %s)\n", 268 data->state, TO_US(ev.duration), TO_STR(ev.pulse)); 269 data->state = STATE_INACTIVE; 270 return -EINVAL; 271 } 272 273 static struct ir_raw_handler rc6_handler = { 274 .protocols = RC_TYPE_RC6, 275 .decode = ir_rc6_decode, 276 }; 277 278 static int __init ir_rc6_decode_init(void) 279 { 280 ir_raw_handler_register(&rc6_handler); 281 282 printk(KERN_INFO "IR RC6 protocol handler initialized\n"); 283 return 0; 284 } 285 286 static void __exit ir_rc6_decode_exit(void) 287 { 288 ir_raw_handler_unregister(&rc6_handler); 289 } 290 291 module_init(ir_rc6_decode_init); 292 module_exit(ir_rc6_decode_exit); 293 294 MODULE_LICENSE("GPL"); 295 MODULE_AUTHOR("David Härdeman <david@hardeman.nu>"); 296 MODULE_DESCRIPTION("RC6 IR protocol decoder"); 297