1 /* ir-rc5-decoder.c - decoder for RC5(x) and StreamZap protocols 2 * 3 * Copyright (C) 2010 by Mauro Carvalho Chehab 4 * Copyright (C) 2010 by Jarod Wilson <jarod@redhat.com> 5 * 6 * This program is free software; you can redistribute it and/or modify 7 * it under the terms of the GNU General Public License as published by 8 * the Free Software Foundation version 2 of the License. 9 * 10 * This program is distributed in the hope that it will be useful, 11 * but WITHOUT ANY WARRANTY; without even the implied warranty of 12 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 13 * GNU General Public License for more details. 14 */ 15 16 /* 17 * This decoder handles the 14 bit RC5 protocol, 15 bit "StreamZap" protocol 18 * and 20 bit RC5x protocol. 19 */ 20 21 #include "rc-core-priv.h" 22 #include <linux/module.h> 23 24 #define RC5_NBITS 14 25 #define RC5_SZ_NBITS 15 26 #define RC5X_NBITS 20 27 #define CHECK_RC5X_NBITS 8 28 #define RC5_UNIT 888888 /* ns */ 29 #define RC5_BIT_START (1 * RC5_UNIT) 30 #define RC5_BIT_END (1 * RC5_UNIT) 31 #define RC5X_SPACE (4 * RC5_UNIT) 32 #define RC5_TRAILER (10 * RC5_UNIT) /* In reality, approx 100 */ 33 34 enum rc5_state { 35 STATE_INACTIVE, 36 STATE_BIT_START, 37 STATE_BIT_END, 38 STATE_CHECK_RC5X, 39 STATE_FINISHED, 40 }; 41 42 /** 43 * ir_rc5_decode() - Decode one RC-5 pulse or space 44 * @dev: the struct rc_dev descriptor of the device 45 * @ev: the struct ir_raw_event descriptor of the pulse/space 46 * 47 * This function returns -EINVAL if the pulse violates the state machine 48 */ 49 static int ir_rc5_decode(struct rc_dev *dev, struct ir_raw_event ev) 50 { 51 struct rc5_dec *data = &dev->raw->rc5; 52 u8 toggle; 53 u32 scancode; 54 enum rc_type protocol; 55 56 if (!(dev->enabled_protocols & (RC_BIT_RC5 | RC_BIT_RC5X | RC_BIT_RC5_SZ))) 57 return 0; 58 59 if (!is_timing_event(ev)) { 60 if (ev.reset) 61 data->state = STATE_INACTIVE; 62 return 0; 63 } 64 65 if (!geq_margin(ev.duration, RC5_UNIT, RC5_UNIT / 2)) 66 goto out; 67 68 again: 69 IR_dprintk(2, "RC5(x/sz) decode started at state %i (%uus %s)\n", 70 data->state, TO_US(ev.duration), TO_STR(ev.pulse)); 71 72 if (!geq_margin(ev.duration, RC5_UNIT, RC5_UNIT / 2)) 73 return 0; 74 75 switch (data->state) { 76 77 case STATE_INACTIVE: 78 if (!ev.pulse) 79 break; 80 81 data->state = STATE_BIT_START; 82 data->count = 1; 83 decrease_duration(&ev, RC5_BIT_START); 84 goto again; 85 86 case STATE_BIT_START: 87 if (!ev.pulse && geq_margin(ev.duration, RC5_TRAILER, RC5_UNIT / 2)) { 88 data->state = STATE_FINISHED; 89 goto again; 90 } 91 92 if (!eq_margin(ev.duration, RC5_BIT_START, RC5_UNIT / 2)) 93 break; 94 95 data->bits <<= 1; 96 if (!ev.pulse) 97 data->bits |= 1; 98 data->count++; 99 data->state = STATE_BIT_END; 100 return 0; 101 102 case STATE_BIT_END: 103 if (!is_transition(&ev, &dev->raw->prev_ev)) 104 break; 105 106 if (data->count == CHECK_RC5X_NBITS) 107 data->state = STATE_CHECK_RC5X; 108 else 109 data->state = STATE_BIT_START; 110 111 decrease_duration(&ev, RC5_BIT_END); 112 goto again; 113 114 case STATE_CHECK_RC5X: 115 if (!ev.pulse && geq_margin(ev.duration, RC5X_SPACE, RC5_UNIT / 2)) { 116 data->is_rc5x = true; 117 decrease_duration(&ev, RC5X_SPACE); 118 } else 119 data->is_rc5x = false; 120 data->state = STATE_BIT_START; 121 goto again; 122 123 case STATE_FINISHED: 124 if (ev.pulse) 125 break; 126 127 if (data->is_rc5x && data->count == RC5X_NBITS) { 128 /* RC5X */ 129 u8 xdata, command, system; 130 if (!(dev->enabled_protocols & RC_BIT_RC5X)) { 131 data->state = STATE_INACTIVE; 132 return 0; 133 } 134 xdata = (data->bits & 0x0003F) >> 0; 135 command = (data->bits & 0x00FC0) >> 6; 136 system = (data->bits & 0x1F000) >> 12; 137 toggle = (data->bits & 0x20000) ? 1 : 0; 138 command += (data->bits & 0x01000) ? 0 : 0x40; 139 scancode = system << 16 | command << 8 | xdata; 140 protocol = RC_TYPE_RC5X; 141 142 } else if (!data->is_rc5x && data->count == RC5_NBITS) { 143 /* RC5 */ 144 u8 command, system; 145 if (!(dev->enabled_protocols & RC_BIT_RC5)) { 146 data->state = STATE_INACTIVE; 147 return 0; 148 } 149 command = (data->bits & 0x0003F) >> 0; 150 system = (data->bits & 0x007C0) >> 6; 151 toggle = (data->bits & 0x00800) ? 1 : 0; 152 command += (data->bits & 0x01000) ? 0 : 0x40; 153 scancode = system << 8 | command; 154 protocol = RC_TYPE_RC5; 155 156 } else if (!data->is_rc5x && data->count == RC5_SZ_NBITS) { 157 /* RC5 StreamZap */ 158 u8 command, system; 159 if (!(dev->enabled_protocols & RC_BIT_RC5_SZ)) { 160 data->state = STATE_INACTIVE; 161 return 0; 162 } 163 command = (data->bits & 0x0003F) >> 0; 164 system = (data->bits & 0x02FC0) >> 6; 165 toggle = (data->bits & 0x01000) ? 1 : 0; 166 scancode = system << 6 | command; 167 protocol = RC_TYPE_RC5_SZ; 168 169 } else 170 break; 171 172 IR_dprintk(1, "RC5(x/sz) scancode 0x%06x (p: %u, t: %u)\n", 173 scancode, protocol, toggle); 174 175 rc_keydown(dev, protocol, scancode, toggle); 176 data->state = STATE_INACTIVE; 177 return 0; 178 } 179 180 out: 181 IR_dprintk(1, "RC5(x/sz) decode failed at state %i count %d (%uus %s)\n", 182 data->state, data->count, TO_US(ev.duration), TO_STR(ev.pulse)); 183 data->state = STATE_INACTIVE; 184 return -EINVAL; 185 } 186 187 static struct ir_raw_timings_manchester ir_rc5_timings = { 188 .leader = RC5_UNIT, 189 .pulse_space_start = 0, 190 .clock = RC5_UNIT, 191 .trailer_space = RC5_UNIT * 10, 192 }; 193 194 static struct ir_raw_timings_manchester ir_rc5x_timings[2] = { 195 { 196 .leader = RC5_UNIT, 197 .pulse_space_start = 0, 198 .clock = RC5_UNIT, 199 .trailer_space = RC5X_SPACE, 200 }, 201 { 202 .clock = RC5_UNIT, 203 .trailer_space = RC5_UNIT * 10, 204 }, 205 }; 206 207 static struct ir_raw_timings_manchester ir_rc5_sz_timings = { 208 .leader = RC5_UNIT, 209 .pulse_space_start = 0, 210 .clock = RC5_UNIT, 211 .trailer_space = RC5_UNIT * 10, 212 }; 213 214 static int ir_rc5_validate_filter(const struct rc_scancode_filter *scancode, 215 unsigned int important_bits) 216 { 217 /* all important bits of scancode should be set in mask */ 218 if (~scancode->mask & important_bits) 219 return -EINVAL; 220 /* extra bits in mask should be zero in data */ 221 if (scancode->mask & scancode->data & ~important_bits) 222 return -EINVAL; 223 return 0; 224 } 225 226 /** 227 * ir_rc5_encode() - Encode a scancode as a stream of raw events 228 * 229 * @protocols: allowed protocols 230 * @scancode: scancode filter describing scancode (helps distinguish between 231 * protocol subtypes when scancode is ambiguous) 232 * @events: array of raw ir events to write into 233 * @max: maximum size of @events 234 * 235 * Returns: The number of events written. 236 * -ENOBUFS if there isn't enough space in the array to fit the 237 * encoding. In this case all @max events will have been written. 238 * -EINVAL if the scancode is ambiguous or invalid. 239 */ 240 static int ir_rc5_encode(u64 protocols, 241 const struct rc_scancode_filter *scancode, 242 struct ir_raw_event *events, unsigned int max) 243 { 244 int ret; 245 struct ir_raw_event *e = events; 246 unsigned int data, xdata, command, commandx, system; 247 248 /* Detect protocol and convert scancode to raw data */ 249 if (protocols & RC_BIT_RC5 && 250 !ir_rc5_validate_filter(scancode, 0x1f7f)) { 251 /* decode scancode */ 252 command = (scancode->data & 0x003f) >> 0; 253 commandx = (scancode->data & 0x0040) >> 6; 254 system = (scancode->data & 0x1f00) >> 8; 255 /* encode data */ 256 data = !commandx << 12 | system << 6 | command; 257 258 /* Modulate the data */ 259 ret = ir_raw_gen_manchester(&e, max, &ir_rc5_timings, RC5_NBITS, 260 data); 261 if (ret < 0) 262 return ret; 263 } else if (protocols & RC_BIT_RC5X && 264 !ir_rc5_validate_filter(scancode, 0x1f7f3f)) { 265 /* decode scancode */ 266 xdata = (scancode->data & 0x00003f) >> 0; 267 command = (scancode->data & 0x003f00) >> 8; 268 commandx = (scancode->data & 0x004000) >> 14; 269 system = (scancode->data & 0x1f0000) >> 16; 270 /* commandx and system overlap, bits must match when encoded */ 271 if (commandx == (system & 0x1)) 272 return -EINVAL; 273 /* encode data */ 274 data = 1 << 18 | system << 12 | command << 6 | xdata; 275 276 /* Modulate the data */ 277 ret = ir_raw_gen_manchester(&e, max, &ir_rc5x_timings[0], 278 CHECK_RC5X_NBITS, 279 data >> (RC5X_NBITS-CHECK_RC5X_NBITS)); 280 if (ret < 0) 281 return ret; 282 ret = ir_raw_gen_manchester(&e, max - (e - events), 283 &ir_rc5x_timings[1], 284 RC5X_NBITS - CHECK_RC5X_NBITS, 285 data); 286 if (ret < 0) 287 return ret; 288 } else if (protocols & RC_BIT_RC5_SZ && 289 !ir_rc5_validate_filter(scancode, 0x2fff)) { 290 /* RC5-SZ scancode is raw enough for Manchester as it is */ 291 ret = ir_raw_gen_manchester(&e, max, &ir_rc5_sz_timings, 292 RC5_SZ_NBITS, scancode->data & 0x2fff); 293 if (ret < 0) 294 return ret; 295 } else { 296 return -EINVAL; 297 } 298 299 return e - events; 300 } 301 302 static struct ir_raw_handler rc5_handler = { 303 .protocols = RC_BIT_RC5 | RC_BIT_RC5X | RC_BIT_RC5_SZ, 304 .decode = ir_rc5_decode, 305 .encode = ir_rc5_encode, 306 }; 307 308 static int __init ir_rc5_decode_init(void) 309 { 310 ir_raw_handler_register(&rc5_handler); 311 312 printk(KERN_INFO "IR RC5(x/sz) protocol handler initialized\n"); 313 return 0; 314 } 315 316 static void __exit ir_rc5_decode_exit(void) 317 { 318 ir_raw_handler_unregister(&rc5_handler); 319 } 320 321 module_init(ir_rc5_decode_init); 322 module_exit(ir_rc5_decode_exit); 323 324 MODULE_LICENSE("GPL"); 325 MODULE_AUTHOR("Mauro Carvalho Chehab and Jarod Wilson"); 326 MODULE_AUTHOR("Red Hat Inc. (http://www.redhat.com)"); 327 MODULE_DESCRIPTION("RC5(x/sz) IR protocol decoder"); 328