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 (!is_timing_event(ev)) { 57 if (ev.reset) 58 data->state = STATE_INACTIVE; 59 return 0; 60 } 61 62 if (!geq_margin(ev.duration, RC5_UNIT, RC5_UNIT / 2)) 63 goto out; 64 65 again: 66 IR_dprintk(2, "RC5(x/sz) decode started at state %i (%uus %s)\n", 67 data->state, TO_US(ev.duration), TO_STR(ev.pulse)); 68 69 if (!geq_margin(ev.duration, RC5_UNIT, RC5_UNIT / 2)) 70 return 0; 71 72 switch (data->state) { 73 74 case STATE_INACTIVE: 75 if (!ev.pulse) 76 break; 77 78 data->state = STATE_BIT_START; 79 data->count = 1; 80 decrease_duration(&ev, RC5_BIT_START); 81 goto again; 82 83 case STATE_BIT_START: 84 if (!ev.pulse && geq_margin(ev.duration, RC5_TRAILER, RC5_UNIT / 2)) { 85 data->state = STATE_FINISHED; 86 goto again; 87 } 88 89 if (!eq_margin(ev.duration, RC5_BIT_START, RC5_UNIT / 2)) 90 break; 91 92 data->bits <<= 1; 93 if (!ev.pulse) 94 data->bits |= 1; 95 data->count++; 96 data->state = STATE_BIT_END; 97 return 0; 98 99 case STATE_BIT_END: 100 if (!is_transition(&ev, &dev->raw->prev_ev)) 101 break; 102 103 if (data->count == CHECK_RC5X_NBITS) 104 data->state = STATE_CHECK_RC5X; 105 else 106 data->state = STATE_BIT_START; 107 108 decrease_duration(&ev, RC5_BIT_END); 109 goto again; 110 111 case STATE_CHECK_RC5X: 112 if (!ev.pulse && geq_margin(ev.duration, RC5X_SPACE, RC5_UNIT / 2)) { 113 data->is_rc5x = true; 114 decrease_duration(&ev, RC5X_SPACE); 115 } else 116 data->is_rc5x = false; 117 data->state = STATE_BIT_START; 118 goto again; 119 120 case STATE_FINISHED: 121 if (ev.pulse) 122 break; 123 124 if (data->is_rc5x && data->count == RC5X_NBITS) { 125 /* RC5X */ 126 u8 xdata, command, system; 127 if (!(dev->enabled_protocols & RC_BIT_RC5X)) { 128 data->state = STATE_INACTIVE; 129 return 0; 130 } 131 xdata = (data->bits & 0x0003F) >> 0; 132 command = (data->bits & 0x00FC0) >> 6; 133 system = (data->bits & 0x1F000) >> 12; 134 toggle = (data->bits & 0x20000) ? 1 : 0; 135 command += (data->bits & 0x01000) ? 0 : 0x40; 136 scancode = system << 16 | command << 8 | xdata; 137 protocol = RC_TYPE_RC5X; 138 139 } else if (!data->is_rc5x && data->count == RC5_NBITS) { 140 /* RC5 */ 141 u8 command, system; 142 if (!(dev->enabled_protocols & RC_BIT_RC5)) { 143 data->state = STATE_INACTIVE; 144 return 0; 145 } 146 command = (data->bits & 0x0003F) >> 0; 147 system = (data->bits & 0x007C0) >> 6; 148 toggle = (data->bits & 0x00800) ? 1 : 0; 149 command += (data->bits & 0x01000) ? 0 : 0x40; 150 scancode = system << 8 | command; 151 protocol = RC_TYPE_RC5; 152 153 } else if (!data->is_rc5x && data->count == RC5_SZ_NBITS) { 154 /* RC5 StreamZap */ 155 u8 command, system; 156 if (!(dev->enabled_protocols & RC_BIT_RC5_SZ)) { 157 data->state = STATE_INACTIVE; 158 return 0; 159 } 160 command = (data->bits & 0x0003F) >> 0; 161 system = (data->bits & 0x02FC0) >> 6; 162 toggle = (data->bits & 0x01000) ? 1 : 0; 163 scancode = system << 6 | command; 164 protocol = RC_TYPE_RC5_SZ; 165 166 } else 167 break; 168 169 IR_dprintk(1, "RC5(x/sz) scancode 0x%06x (p: %u, t: %u)\n", 170 scancode, protocol, toggle); 171 172 rc_keydown(dev, protocol, scancode, toggle); 173 data->state = STATE_INACTIVE; 174 return 0; 175 } 176 177 out: 178 IR_dprintk(1, "RC5(x/sz) decode failed at state %i count %d (%uus %s)\n", 179 data->state, data->count, TO_US(ev.duration), TO_STR(ev.pulse)); 180 data->state = STATE_INACTIVE; 181 return -EINVAL; 182 } 183 184 static struct ir_raw_handler rc5_handler = { 185 .protocols = RC_BIT_RC5 | RC_BIT_RC5X | RC_BIT_RC5_SZ, 186 .decode = ir_rc5_decode, 187 }; 188 189 static int __init ir_rc5_decode_init(void) 190 { 191 ir_raw_handler_register(&rc5_handler); 192 193 printk(KERN_INFO "IR RC5(x/sz) protocol handler initialized\n"); 194 return 0; 195 } 196 197 static void __exit ir_rc5_decode_exit(void) 198 { 199 ir_raw_handler_unregister(&rc5_handler); 200 } 201 202 module_init(ir_rc5_decode_init); 203 module_exit(ir_rc5_decode_exit); 204 205 MODULE_LICENSE("GPL"); 206 MODULE_AUTHOR("Mauro Carvalho Chehab and Jarod Wilson"); 207 MODULE_AUTHOR("Red Hat Inc. (http://www.redhat.com)"); 208 MODULE_DESCRIPTION("RC5(x/sz) IR protocol decoder"); 209