1 /* ir-nec-decoder.c - handle NEC 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 #include <linux/bitrev.h> 16 #include "ir-core-priv.h" 17 18 #define NEC_NBITS 32 19 #define NEC_UNIT 562500 /* ns */ 20 #define NEC_HEADER_PULSE (16 * NEC_UNIT) 21 #define NECX_HEADER_PULSE (8 * NEC_UNIT) /* Less common NEC variant */ 22 #define NEC_HEADER_SPACE (8 * NEC_UNIT) 23 #define NEC_REPEAT_SPACE (4 * NEC_UNIT) 24 #define NEC_BIT_PULSE (1 * NEC_UNIT) 25 #define NEC_BIT_0_SPACE (1 * NEC_UNIT) 26 #define NEC_BIT_1_SPACE (3 * NEC_UNIT) 27 #define NEC_TRAILER_PULSE (1 * NEC_UNIT) 28 #define NEC_TRAILER_SPACE (10 * NEC_UNIT) /* even longer in reality */ 29 #define NECX_REPEAT_BITS 1 30 31 enum nec_state { 32 STATE_INACTIVE, 33 STATE_HEADER_SPACE, 34 STATE_BIT_PULSE, 35 STATE_BIT_SPACE, 36 STATE_TRAILER_PULSE, 37 STATE_TRAILER_SPACE, 38 }; 39 40 /** 41 * ir_nec_decode() - Decode one NEC pulse or space 42 * @input_dev: the struct input_dev descriptor of the device 43 * @duration: the struct ir_raw_event descriptor of the pulse/space 44 * 45 * This function returns -EINVAL if the pulse violates the state machine 46 */ 47 static int ir_nec_decode(struct input_dev *input_dev, struct ir_raw_event ev) 48 { 49 struct ir_input_dev *ir_dev = input_get_drvdata(input_dev); 50 struct nec_dec *data = &ir_dev->raw->nec; 51 u32 scancode; 52 u8 address, not_address, command, not_command; 53 54 if (!(ir_dev->raw->enabled_protocols & IR_TYPE_NEC)) 55 return 0; 56 57 if (!is_timing_event(ev)) { 58 if (ev.reset) 59 data->state = STATE_INACTIVE; 60 return 0; 61 } 62 63 IR_dprintk(2, "NEC decode started at state %d (%uus %s)\n", 64 data->state, TO_US(ev.duration), TO_STR(ev.pulse)); 65 66 switch (data->state) { 67 68 case STATE_INACTIVE: 69 if (!ev.pulse) 70 break; 71 72 if (eq_margin(ev.duration, NEC_HEADER_PULSE, NEC_UNIT / 2)) { 73 data->is_nec_x = false; 74 data->necx_repeat = false; 75 } else if (eq_margin(ev.duration, NECX_HEADER_PULSE, NEC_UNIT / 2)) 76 data->is_nec_x = true; 77 else 78 break; 79 80 data->count = 0; 81 data->state = STATE_HEADER_SPACE; 82 return 0; 83 84 case STATE_HEADER_SPACE: 85 if (ev.pulse) 86 break; 87 88 if (eq_margin(ev.duration, NEC_HEADER_SPACE, NEC_UNIT / 2)) { 89 data->state = STATE_BIT_PULSE; 90 return 0; 91 } else if (eq_margin(ev.duration, NEC_REPEAT_SPACE, NEC_UNIT / 2)) { 92 ir_repeat(input_dev); 93 IR_dprintk(1, "Repeat last key\n"); 94 data->state = STATE_TRAILER_PULSE; 95 return 0; 96 } 97 98 break; 99 100 case STATE_BIT_PULSE: 101 if (!ev.pulse) 102 break; 103 104 if (!eq_margin(ev.duration, NEC_BIT_PULSE, NEC_UNIT / 2)) 105 break; 106 107 data->state = STATE_BIT_SPACE; 108 return 0; 109 110 case STATE_BIT_SPACE: 111 if (ev.pulse) 112 break; 113 114 if (data->necx_repeat && data->count == NECX_REPEAT_BITS && 115 geq_margin(ev.duration, 116 NEC_TRAILER_SPACE, NEC_UNIT / 2)) { 117 IR_dprintk(1, "Repeat last key\n"); 118 ir_repeat(input_dev); 119 data->state = STATE_INACTIVE; 120 return 0; 121 122 } else if (data->count > NECX_REPEAT_BITS) 123 data->necx_repeat = false; 124 125 data->bits <<= 1; 126 if (eq_margin(ev.duration, NEC_BIT_1_SPACE, NEC_UNIT / 2)) 127 data->bits |= 1; 128 else if (!eq_margin(ev.duration, NEC_BIT_0_SPACE, NEC_UNIT / 2)) 129 break; 130 data->count++; 131 132 if (data->count == NEC_NBITS) 133 data->state = STATE_TRAILER_PULSE; 134 else 135 data->state = STATE_BIT_PULSE; 136 137 return 0; 138 139 case STATE_TRAILER_PULSE: 140 if (!ev.pulse) 141 break; 142 143 if (!eq_margin(ev.duration, NEC_TRAILER_PULSE, NEC_UNIT / 2)) 144 break; 145 146 data->state = STATE_TRAILER_SPACE; 147 return 0; 148 149 case STATE_TRAILER_SPACE: 150 if (ev.pulse) 151 break; 152 153 if (!geq_margin(ev.duration, NEC_TRAILER_SPACE, NEC_UNIT / 2)) 154 break; 155 156 address = bitrev8((data->bits >> 24) & 0xff); 157 not_address = bitrev8((data->bits >> 16) & 0xff); 158 command = bitrev8((data->bits >> 8) & 0xff); 159 not_command = bitrev8((data->bits >> 0) & 0xff); 160 161 if ((command ^ not_command) != 0xff) { 162 IR_dprintk(1, "NEC checksum error: received 0x%08x\n", 163 data->bits); 164 break; 165 } 166 167 if ((address ^ not_address) != 0xff) { 168 /* Extended NEC */ 169 scancode = address << 16 | 170 not_address << 8 | 171 command; 172 IR_dprintk(1, "NEC (Ext) scancode 0x%06x\n", scancode); 173 } else { 174 /* Normal NEC */ 175 scancode = address << 8 | command; 176 IR_dprintk(1, "NEC scancode 0x%04x\n", scancode); 177 } 178 179 if (data->is_nec_x) 180 data->necx_repeat = true; 181 182 ir_keydown(input_dev, scancode, 0); 183 data->state = STATE_INACTIVE; 184 return 0; 185 } 186 187 IR_dprintk(1, "NEC decode failed at state %d (%uus %s)\n", 188 data->state, TO_US(ev.duration), TO_STR(ev.pulse)); 189 data->state = STATE_INACTIVE; 190 return -EINVAL; 191 } 192 193 static struct ir_raw_handler nec_handler = { 194 .protocols = IR_TYPE_NEC, 195 .decode = ir_nec_decode, 196 }; 197 198 static int __init ir_nec_decode_init(void) 199 { 200 ir_raw_handler_register(&nec_handler); 201 202 printk(KERN_INFO "IR NEC protocol handler initialized\n"); 203 return 0; 204 } 205 206 static void __exit ir_nec_decode_exit(void) 207 { 208 ir_raw_handler_unregister(&nec_handler); 209 } 210 211 module_init(ir_nec_decode_init); 212 module_exit(ir_nec_decode_exit); 213 214 MODULE_LICENSE("GPL"); 215 MODULE_AUTHOR("Mauro Carvalho Chehab <mchehab@redhat.com>"); 216 MODULE_AUTHOR("Red Hat Inc. (http://www.redhat.com)"); 217 MODULE_DESCRIPTION("NEC IR protocol decoder"); 218