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 29 enum 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 */ 42 static 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 (!is_timing_event(ev)) { 47 if (ev.reset) 48 data->state = STATE_INACTIVE; 49 return 0; 50 } 51 52 IR_dprintk(2, "XMP decode started at state %d %d (%uus %s)\n", 53 data->state, data->count, TO_US(ev.duration), TO_STR(ev.pulse)); 54 55 switch (data->state) { 56 57 case STATE_INACTIVE: 58 if (!ev.pulse) 59 break; 60 61 if (eq_margin(ev.duration, XMP_LEADER, XMP_UNIT / 2)) { 62 data->count = 0; 63 data->state = STATE_NIBBLE_SPACE; 64 } 65 66 return 0; 67 68 case STATE_LEADER_PULSE: 69 if (!ev.pulse) 70 break; 71 72 if (eq_margin(ev.duration, XMP_LEADER, XMP_UNIT / 2)) 73 data->state = STATE_NIBBLE_SPACE; 74 75 return 0; 76 77 case STATE_NIBBLE_SPACE: 78 if (ev.pulse) 79 break; 80 81 if (geq_margin(ev.duration, XMP_TRAILER_SPACE, XMP_NIBBLE_PREFIX)) { 82 int divider, i; 83 u8 addr, subaddr, subaddr2, toggle, oem, obc1, obc2, sum1, sum2; 84 u32 *n; 85 u32 scancode; 86 87 if (data->count != 16) { 88 IR_dprintk(2, "received TRAILER period at index %d: %u\n", 89 data->count, ev.duration); 90 data->state = STATE_INACTIVE; 91 return -EINVAL; 92 } 93 94 n = data->durations; 95 /* 96 * the 4th nibble should be 15 so base the divider on this 97 * to transform durations into nibbles. Substract 2000 from 98 * the divider to compensate for fluctuations in the signal 99 */ 100 divider = (n[3] - XMP_NIBBLE_PREFIX) / 15 - 2000; 101 if (divider < 50) { 102 IR_dprintk(2, "divider to small %d.\n", divider); 103 data->state = STATE_INACTIVE; 104 return -EINVAL; 105 } 106 107 /* convert to nibbles and do some sanity checks */ 108 for (i = 0; i < 16; i++) 109 n[i] = (n[i] - XMP_NIBBLE_PREFIX) / divider; 110 sum1 = (15 + n[0] + n[1] + n[2] + n[3] + 111 n[4] + n[5] + n[6] + n[7]) % 16; 112 sum2 = (15 + n[8] + n[9] + n[10] + n[11] + 113 n[12] + n[13] + n[14] + n[15]) % 16; 114 115 if (sum1 != 15 || sum2 != 15) { 116 IR_dprintk(2, "checksum errors sum1=0x%X sum2=0x%X\n", 117 sum1, sum2); 118 data->state = STATE_INACTIVE; 119 return -EINVAL; 120 } 121 122 subaddr = n[0] << 4 | n[2]; 123 subaddr2 = n[8] << 4 | n[11]; 124 oem = n[4] << 4 | n[5]; 125 addr = n[6] << 4 | n[7]; 126 toggle = n[10]; 127 obc1 = n[12] << 4 | n[13]; 128 obc2 = n[14] << 4 | n[15]; 129 if (subaddr != subaddr2) { 130 IR_dprintk(2, "subaddress nibbles mismatch 0x%02X != 0x%02X\n", 131 subaddr, subaddr2); 132 data->state = STATE_INACTIVE; 133 return -EINVAL; 134 } 135 if (oem != 0x44) 136 IR_dprintk(1, "Warning: OEM nibbles 0x%02X. Expected 0x44\n", 137 oem); 138 139 scancode = addr << 24 | subaddr << 16 | 140 obc1 << 8 | obc2; 141 IR_dprintk(1, "XMP scancode 0x%06x\n", scancode); 142 143 if (toggle == 0) { 144 rc_keydown(dev, RC_PROTO_XMP, scancode, 0); 145 } else { 146 rc_repeat(dev); 147 IR_dprintk(1, "Repeat last key\n"); 148 } 149 data->state = STATE_INACTIVE; 150 151 return 0; 152 153 } else if (geq_margin(ev.duration, XMP_HALFFRAME_SPACE, XMP_NIBBLE_PREFIX)) { 154 /* Expect 8 or 16 nibble pulses. 16 in case of 'final' frame */ 155 if (data->count == 16) { 156 IR_dprintk(2, "received half frame pulse at index %d. Probably a final frame key-up event: %u\n", 157 data->count, ev.duration); 158 /* 159 * TODO: for now go back to half frame position 160 * so trailer can be found and key press 161 * can be handled. 162 */ 163 data->count = 8; 164 } 165 166 else if (data->count != 8) 167 IR_dprintk(2, "received half frame pulse at index %d: %u\n", 168 data->count, ev.duration); 169 data->state = STATE_LEADER_PULSE; 170 171 return 0; 172 173 } else if (geq_margin(ev.duration, XMP_NIBBLE_PREFIX, XMP_UNIT)) { 174 /* store nibble raw data, decode after trailer */ 175 if (data->count == 16) { 176 IR_dprintk(2, "to many pulses (%d) ignoring: %u\n", 177 data->count, ev.duration); 178 data->state = STATE_INACTIVE; 179 return -EINVAL; 180 } 181 data->durations[data->count] = ev.duration; 182 data->count++; 183 data->state = STATE_LEADER_PULSE; 184 185 return 0; 186 187 } 188 189 break; 190 } 191 192 IR_dprintk(1, "XMP decode failed at count %d state %d (%uus %s)\n", 193 data->count, data->state, TO_US(ev.duration), TO_STR(ev.pulse)); 194 data->state = STATE_INACTIVE; 195 return -EINVAL; 196 } 197 198 static struct ir_raw_handler xmp_handler = { 199 .protocols = RC_PROTO_BIT_XMP, 200 .decode = ir_xmp_decode, 201 }; 202 203 static int __init ir_xmp_decode_init(void) 204 { 205 ir_raw_handler_register(&xmp_handler); 206 207 printk(KERN_INFO "IR XMP protocol handler initialized\n"); 208 return 0; 209 } 210 211 static void __exit ir_xmp_decode_exit(void) 212 { 213 ir_raw_handler_unregister(&xmp_handler); 214 } 215 216 module_init(ir_xmp_decode_init); 217 module_exit(ir_xmp_decode_exit); 218 219 MODULE_LICENSE("GPL"); 220 MODULE_AUTHOR("Marcel Mol <marcel@mesa.nl>"); 221 MODULE_AUTHOR("MESA Consulting (http://www.mesa.nl)"); 222 MODULE_DESCRIPTION("XMP IR protocol decoder"); 223