1 /* ir-rc5-decoder.c - handle RC5(x) IR Pulse/Space protocol 2 * 3 * Copyright (C) 2010 by Mauro Carvalho Chehab <mchehab@redhat.com> 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 /* 16 * This code handles 14 bits RC5 protocols and 20 bits RC5x protocols. 17 * There are other variants that use a different number of bits. 18 * This is currently unsupported. 19 * It considers a carrier of 36 kHz, with a total of 14/20 bits, where 20 * the first two bits are start bits, and a third one is a filing bit 21 */ 22 23 #include "rc-core-priv.h" 24 #include <linux/module.h> 25 26 #define RC5_NBITS 14 27 #define RC5X_NBITS 20 28 #define CHECK_RC5X_NBITS 8 29 #define RC5_UNIT 888888 /* ns */ 30 #define RC5_BIT_START (1 * RC5_UNIT) 31 #define RC5_BIT_END (1 * RC5_UNIT) 32 #define RC5X_SPACE (4 * RC5_UNIT) 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 55 if (!(dev->raw->enabled_protocols & (RC_BIT_RC5 | RC_BIT_RC5X))) 56 return 0; 57 58 if (!is_timing_event(ev)) { 59 if (ev.reset) 60 data->state = STATE_INACTIVE; 61 return 0; 62 } 63 64 if (!geq_margin(ev.duration, RC5_UNIT, RC5_UNIT / 2)) 65 goto out; 66 67 again: 68 IR_dprintk(2, "RC5(x) decode started at state %i (%uus %s)\n", 69 data->state, TO_US(ev.duration), TO_STR(ev.pulse)); 70 71 if (!geq_margin(ev.duration, RC5_UNIT, RC5_UNIT / 2)) 72 return 0; 73 74 switch (data->state) { 75 76 case STATE_INACTIVE: 77 if (!ev.pulse) 78 break; 79 80 data->state = STATE_BIT_START; 81 data->count = 1; 82 /* We just need enough bits to get to STATE_CHECK_RC5X */ 83 data->wanted_bits = RC5X_NBITS; 84 decrease_duration(&ev, RC5_BIT_START); 85 goto again; 86 87 case STATE_BIT_START: 88 if (!eq_margin(ev.duration, RC5_BIT_START, RC5_UNIT / 2)) 89 break; 90 91 data->bits <<= 1; 92 if (!ev.pulse) 93 data->bits |= 1; 94 data->count++; 95 data->state = STATE_BIT_END; 96 return 0; 97 98 case STATE_BIT_END: 99 if (!is_transition(&ev, &dev->raw->prev_ev)) 100 break; 101 102 if (data->count == data->wanted_bits) 103 data->state = STATE_FINISHED; 104 else if (data->count == CHECK_RC5X_NBITS) 105 data->state = STATE_CHECK_RC5X; 106 else 107 data->state = STATE_BIT_START; 108 109 decrease_duration(&ev, RC5_BIT_END); 110 goto again; 111 112 case STATE_CHECK_RC5X: 113 if (!ev.pulse && geq_margin(ev.duration, RC5X_SPACE, RC5_UNIT / 2)) { 114 /* RC5X */ 115 data->wanted_bits = RC5X_NBITS; 116 decrease_duration(&ev, RC5X_SPACE); 117 } else { 118 /* RC5 */ 119 data->wanted_bits = RC5_NBITS; 120 } 121 data->state = STATE_BIT_START; 122 goto again; 123 124 case STATE_FINISHED: 125 if (ev.pulse) 126 break; 127 128 if (data->wanted_bits == RC5X_NBITS) { 129 /* RC5X */ 130 u8 xdata, command, system; 131 if (!(dev->raw->enabled_protocols & RC_BIT_RC5X)) { 132 data->state = STATE_INACTIVE; 133 return 0; 134 } 135 xdata = (data->bits & 0x0003F) >> 0; 136 command = (data->bits & 0x00FC0) >> 6; 137 system = (data->bits & 0x1F000) >> 12; 138 toggle = (data->bits & 0x20000) ? 1 : 0; 139 command += (data->bits & 0x01000) ? 0 : 0x40; 140 scancode = system << 16 | command << 8 | xdata; 141 142 IR_dprintk(1, "RC5X scancode 0x%06x (toggle: %u)\n", 143 scancode, toggle); 144 145 } else { 146 /* RC5 */ 147 u8 command, system; 148 if (!(dev->raw->enabled_protocols & RC_BIT_RC5)) { 149 data->state = STATE_INACTIVE; 150 return 0; 151 } 152 command = (data->bits & 0x0003F) >> 0; 153 system = (data->bits & 0x007C0) >> 6; 154 toggle = (data->bits & 0x00800) ? 1 : 0; 155 command += (data->bits & 0x01000) ? 0 : 0x40; 156 scancode = system << 8 | command; 157 158 IR_dprintk(1, "RC5 scancode 0x%04x (toggle: %u)\n", 159 scancode, toggle); 160 } 161 162 rc_keydown(dev, scancode, toggle); 163 data->state = STATE_INACTIVE; 164 return 0; 165 } 166 167 out: 168 IR_dprintk(1, "RC5(x) decode failed at state %i (%uus %s)\n", 169 data->state, TO_US(ev.duration), TO_STR(ev.pulse)); 170 data->state = STATE_INACTIVE; 171 return -EINVAL; 172 } 173 174 static struct ir_raw_handler rc5_handler = { 175 .protocols = RC_BIT_RC5 | RC_BIT_RC5X, 176 .decode = ir_rc5_decode, 177 }; 178 179 static int __init ir_rc5_decode_init(void) 180 { 181 ir_raw_handler_register(&rc5_handler); 182 183 printk(KERN_INFO "IR RC5(x) protocol handler initialized\n"); 184 return 0; 185 } 186 187 static void __exit ir_rc5_decode_exit(void) 188 { 189 ir_raw_handler_unregister(&rc5_handler); 190 } 191 192 module_init(ir_rc5_decode_init); 193 module_exit(ir_rc5_decode_exit); 194 195 MODULE_LICENSE("GPL"); 196 MODULE_AUTHOR("Mauro Carvalho Chehab <mchehab@redhat.com>"); 197 MODULE_AUTHOR("Red Hat Inc. (http://www.redhat.com)"); 198 MODULE_DESCRIPTION("RC5(x) IR protocol decoder"); 199