1/* ir-xmp-decoder.c - handle XMP IR Pulse/Space protocol 2 * 3 * Copyright (C) 2014 by Marcel Mol 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 * - Based on info from http://www.hifi-remote.com 15 * - Ignore Toggle=9 frames 16 * - Ignore XMP-1 XMP-2 difference, always store 16 bit OBC 17 */ 18 19#include <linux/bitrev.h> 20#include <linux/module.h> 21#include "rc-core-priv.h" 22 23#define XMP_UNIT 136000 /* ns */ 24#define XMP_LEADER 210000 /* ns */ 25#define XMP_NIBBLE_PREFIX 760000 /* ns */ 26#define XMP_HALFFRAME_SPACE 13800000 /* ns */ 27#define XMP_TRAILER_SPACE 20000000 /* should be 80ms but not all dureation supliers can go that high */ 28 29enum xmp_state { 30 STATE_INACTIVE, 31 STATE_LEADER_PULSE, 32 STATE_NIBBLE_SPACE, 33}; 34 35/** 36 * ir_xmp_decode() - Decode one XMP pulse or space 37 * @dev: the struct rc_dev descriptor of the device 38 * @duration: the struct ir_raw_event descriptor of the pulse/space 39 * 40 * This function returns -EINVAL if the pulse violates the state machine 41 */ 42static int ir_xmp_decode(struct rc_dev *dev, struct ir_raw_event ev) 43{ 44 struct xmp_dec *data = &dev->raw->xmp; 45 46 if (!(dev->enabled_protocols & RC_BIT_XMP)) 47 return 0; 48 49 if (!is_timing_event(ev)) { 50 if (ev.reset) 51 data->state = STATE_INACTIVE; 52 return 0; 53 } 54 55 IR_dprintk(2, "XMP decode started at state %d %d (%uus %s)\n", 56 data->state, data->count, TO_US(ev.duration), TO_STR(ev.pulse)); 57 58 switch (data->state) { 59 60 case STATE_INACTIVE: 61 if (!ev.pulse) 62 break; 63 64 if (eq_margin(ev.duration, XMP_LEADER, XMP_UNIT / 2)) { 65 data->count = 0; 66 data->state = STATE_NIBBLE_SPACE; 67 } 68 69 return 0; 70 71 case STATE_LEADER_PULSE: 72 if (!ev.pulse) 73 break; 74 75 if (eq_margin(ev.duration, XMP_LEADER, XMP_UNIT / 2)) 76 data->state = STATE_NIBBLE_SPACE; 77 78 return 0; 79 80 case STATE_NIBBLE_SPACE: 81 if (ev.pulse) 82 break; 83 84 if (geq_margin(ev.duration, XMP_TRAILER_SPACE, XMP_NIBBLE_PREFIX)) { 85 int divider, i; 86 u8 addr, subaddr, subaddr2, toggle, oem, obc1, obc2, sum1, sum2; 87 u32 *n; 88 u32 scancode; 89 90 if (data->count != 16) { 91 IR_dprintk(2, "received TRAILER period at index %d: %u\n", 92 data->count, ev.duration); 93 data->state = STATE_INACTIVE; 94 return -EINVAL; 95 } 96 97 n = data->durations; 98 /* 99 * the 4th nibble should be 15 so base the divider on this 100 * to transform durations into nibbles. Substract 2000 from 101 * the divider to compensate for fluctuations in the signal 102 */ 103 divider = (n[3] - XMP_NIBBLE_PREFIX) / 15 - 2000; 104 if (divider < 50) { 105 IR_dprintk(2, "divider to small %d.\n", divider); 106 data->state = STATE_INACTIVE; 107 return -EINVAL; 108 } 109 110 /* convert to nibbles and do some sanity checks */ 111 for (i = 0; i < 16; i++) 112 n[i] = (n[i] - XMP_NIBBLE_PREFIX) / divider; 113 sum1 = (15 + n[0] + n[1] + n[2] + n[3] + 114 n[4] + n[5] + n[6] + n[7]) % 16; 115 sum2 = (15 + n[8] + n[9] + n[10] + n[11] + 116 n[12] + n[13] + n[14] + n[15]) % 16; 117 118 if (sum1 != 15 || sum2 != 15) { 119 IR_dprintk(2, "checksum errors sum1=0x%X sum2=0x%X\n", 120 sum1, sum2); 121 data->state = STATE_INACTIVE; 122 return -EINVAL; 123 } 124 125 subaddr = n[0] << 4 | n[2]; 126 subaddr2 = n[8] << 4 | n[11]; 127 oem = n[4] << 4 | n[5]; 128 addr = n[6] << 4 | n[7]; 129 toggle = n[10]; 130 obc1 = n[12] << 4 | n[13]; 131 obc2 = n[14] << 4 | n[15]; 132 if (subaddr != subaddr2) { 133 IR_dprintk(2, "subaddress nibbles mismatch 0x%02X != 0x%02X\n", 134 subaddr, subaddr2); 135 data->state = STATE_INACTIVE; 136 return -EINVAL; 137 } 138 if (oem != 0x44) 139 IR_dprintk(1, "Warning: OEM nibbles 0x%02X. Expected 0x44\n", 140 oem); 141 142 scancode = addr << 24 | subaddr << 16 | 143 obc1 << 8 | obc2; 144 IR_dprintk(1, "XMP scancode 0x%06x\n", scancode); 145 146 if (toggle == 0) { 147 rc_keydown(dev, RC_TYPE_XMP, scancode, 0); 148 } else { 149 rc_repeat(dev); 150 IR_dprintk(1, "Repeat last key\n"); 151 } 152 data->state = STATE_INACTIVE; 153 154 return 0; 155 156 } else if (geq_margin(ev.duration, XMP_HALFFRAME_SPACE, XMP_NIBBLE_PREFIX)) { 157 /* Expect 8 or 16 nibble pulses. 16 in case of 'final' frame */ 158 if (data->count == 16) { 159 IR_dprintk(2, "received half frame pulse at index %d. Probably a final frame key-up event: %u\n", 160 data->count, ev.duration); 161 /* 162 * TODO: for now go back to half frame position 163 * so trailer can be found and key press 164 * can be handled. 165 */ 166 data->count = 8; 167 } 168 169 else if (data->count != 8) 170 IR_dprintk(2, "received half frame pulse at index %d: %u\n", 171 data->count, ev.duration); 172 data->state = STATE_LEADER_PULSE; 173 174 return 0; 175 176 } else if (geq_margin(ev.duration, XMP_NIBBLE_PREFIX, XMP_UNIT)) { 177 /* store nibble raw data, decode after trailer */ 178 if (data->count == 16) { 179 IR_dprintk(2, "to many pulses (%d) ignoring: %u\n", 180 data->count, ev.duration); 181 data->state = STATE_INACTIVE; 182 return -EINVAL; 183 } 184 data->durations[data->count] = ev.duration; 185 data->count++; 186 data->state = STATE_LEADER_PULSE; 187 188 return 0; 189 190 } 191 192 break; 193 } 194 195 IR_dprintk(1, "XMP decode failed at count %d state %d (%uus %s)\n", 196 data->count, data->state, TO_US(ev.duration), TO_STR(ev.pulse)); 197 data->state = STATE_INACTIVE; 198 return -EINVAL; 199} 200 201static struct ir_raw_handler xmp_handler = { 202 .protocols = RC_BIT_XMP, 203 .decode = ir_xmp_decode, 204}; 205 206static int __init ir_xmp_decode_init(void) 207{ 208 ir_raw_handler_register(&xmp_handler); 209 210 printk(KERN_INFO "IR XMP protocol handler initialized\n"); 211 return 0; 212} 213 214static void __exit ir_xmp_decode_exit(void) 215{ 216 ir_raw_handler_unregister(&xmp_handler); 217} 218 219module_init(ir_xmp_decode_init); 220module_exit(ir_xmp_decode_exit); 221 222MODULE_LICENSE("GPL"); 223MODULE_AUTHOR("Marcel Mol <marcel@mesa.nl>"); 224MODULE_AUTHOR("MESA Consulting (http://www.mesa.nl)"); 225MODULE_DESCRIPTION("XMP IR protocol decoder"); 226