1// SPDX-License-Identifier: GPL-2.0-only 2/* ir-xmp-decoder.c - handle XMP IR Pulse/Space protocol 3 * 4 * Copyright (C) 2014 by Marcel Mol 5 * 6 * - Based on info from http://www.hifi-remote.com 7 * - Ignore Toggle=9 frames 8 * - Ignore XMP-1 XMP-2 difference, always store 16 bit OBC 9 */ 10 11#include <linux/bitrev.h> 12#include <linux/module.h> 13#include "rc-core-priv.h" 14 15#define XMP_UNIT 136 /* us */ 16#define XMP_LEADER 210 /* us */ 17#define XMP_NIBBLE_PREFIX 760 /* us */ 18#define XMP_HALFFRAME_SPACE 13800 /* us */ 19/* should be 80ms but not all duration supliers can go that high */ 20#define XMP_TRAILER_SPACE 20000 21 22enum xmp_state { 23 STATE_INACTIVE, 24 STATE_LEADER_PULSE, 25 STATE_NIBBLE_SPACE, 26}; 27 28/** 29 * ir_xmp_decode() - Decode one XMP pulse or space 30 * @dev: the struct rc_dev descriptor of the device 31 * @ev: the struct ir_raw_event descriptor of the pulse/space 32 * 33 * This function returns -EINVAL if the pulse violates the state machine 34 */ 35static int ir_xmp_decode(struct rc_dev *dev, struct ir_raw_event ev) 36{ 37 struct xmp_dec *data = &dev->raw->xmp; 38 39 if (!is_timing_event(ev)) { 40 if (ev.overflow) 41 data->state = STATE_INACTIVE; 42 return 0; 43 } 44 45 dev_dbg(&dev->dev, "XMP decode started at state %d %d (%uus %s)\n", 46 data->state, data->count, ev.duration, TO_STR(ev.pulse)); 47 48 switch (data->state) { 49 50 case STATE_INACTIVE: 51 if (!ev.pulse) 52 break; 53 54 if (eq_margin(ev.duration, XMP_LEADER, XMP_UNIT / 2)) { 55 data->count = 0; 56 data->state = STATE_NIBBLE_SPACE; 57 } 58 59 return 0; 60 61 case STATE_LEADER_PULSE: 62 if (!ev.pulse) 63 break; 64 65 if (eq_margin(ev.duration, XMP_LEADER, XMP_UNIT / 2)) 66 data->state = STATE_NIBBLE_SPACE; 67 68 return 0; 69 70 case STATE_NIBBLE_SPACE: 71 if (ev.pulse) 72 break; 73 74 if (geq_margin(ev.duration, XMP_TRAILER_SPACE, XMP_NIBBLE_PREFIX)) { 75 int divider, i; 76 u8 addr, subaddr, subaddr2, toggle, oem, obc1, obc2, sum1, sum2; 77 u32 *n; 78 u32 scancode; 79 80 if (data->count != 16) { 81 dev_dbg(&dev->dev, "received TRAILER period at index %d: %u\n", 82 data->count, ev.duration); 83 data->state = STATE_INACTIVE; 84 return -EINVAL; 85 } 86 87 n = data->durations; 88 /* 89 * the 4th nibble should be 15 so base the divider on this 90 * to transform durations into nibbles. Subtract 2000 from 91 * the divider to compensate for fluctuations in the signal 92 */ 93 divider = (n[3] - XMP_NIBBLE_PREFIX) / 15 - 2000; 94 if (divider < 50) { 95 dev_dbg(&dev->dev, "divider to small %d.\n", 96 divider); 97 data->state = STATE_INACTIVE; 98 return -EINVAL; 99 } 100 101 /* convert to nibbles and do some sanity checks */ 102 for (i = 0; i < 16; i++) 103 n[i] = (n[i] - XMP_NIBBLE_PREFIX) / divider; 104 sum1 = (15 + n[0] + n[1] + n[2] + n[3] + 105 n[4] + n[5] + n[6] + n[7]) % 16; 106 sum2 = (15 + n[8] + n[9] + n[10] + n[11] + 107 n[12] + n[13] + n[14] + n[15]) % 16; 108 109 if (sum1 != 15 || sum2 != 15) { 110 dev_dbg(&dev->dev, "checksum errors sum1=0x%X sum2=0x%X\n", 111 sum1, sum2); 112 data->state = STATE_INACTIVE; 113 return -EINVAL; 114 } 115 116 subaddr = n[0] << 4 | n[2]; 117 subaddr2 = n[8] << 4 | n[11]; 118 oem = n[4] << 4 | n[5]; 119 addr = n[6] << 4 | n[7]; 120 toggle = n[10]; 121 obc1 = n[12] << 4 | n[13]; 122 obc2 = n[14] << 4 | n[15]; 123 if (subaddr != subaddr2) { 124 dev_dbg(&dev->dev, "subaddress nibbles mismatch 0x%02X != 0x%02X\n", 125 subaddr, subaddr2); 126 data->state = STATE_INACTIVE; 127 return -EINVAL; 128 } 129 if (oem != 0x44) 130 dev_dbg(&dev->dev, "Warning: OEM nibbles 0x%02X. Expected 0x44\n", 131 oem); 132 133 scancode = addr << 24 | subaddr << 16 | 134 obc1 << 8 | obc2; 135 dev_dbg(&dev->dev, "XMP scancode 0x%06x\n", scancode); 136 137 if (toggle == 0) { 138 rc_keydown(dev, RC_PROTO_XMP, scancode, 0); 139 } else { 140 rc_repeat(dev); 141 dev_dbg(&dev->dev, "Repeat last key\n"); 142 } 143 data->state = STATE_INACTIVE; 144 145 return 0; 146 147 } else if (geq_margin(ev.duration, XMP_HALFFRAME_SPACE, XMP_NIBBLE_PREFIX)) { 148 /* Expect 8 or 16 nibble pulses. 16 in case of 'final' frame */ 149 if (data->count == 16) { 150 dev_dbg(&dev->dev, "received half frame pulse at index %d. Probably a final frame key-up event: %u\n", 151 data->count, ev.duration); 152 /* 153 * TODO: for now go back to half frame position 154 * so trailer can be found and key press 155 * can be handled. 156 */ 157 data->count = 8; 158 } 159 160 else if (data->count != 8) 161 dev_dbg(&dev->dev, "received half frame pulse at index %d: %u\n", 162 data->count, ev.duration); 163 data->state = STATE_LEADER_PULSE; 164 165 return 0; 166 167 } else if (geq_margin(ev.duration, XMP_NIBBLE_PREFIX, XMP_UNIT)) { 168 /* store nibble raw data, decode after trailer */ 169 if (data->count == 16) { 170 dev_dbg(&dev->dev, "too many pulses (%d) ignoring: %u\n", 171 data->count, ev.duration); 172 data->state = STATE_INACTIVE; 173 return -EINVAL; 174 } 175 data->durations[data->count] = ev.duration; 176 data->count++; 177 data->state = STATE_LEADER_PULSE; 178 179 return 0; 180 181 } 182 183 break; 184 } 185 186 dev_dbg(&dev->dev, "XMP decode failed at count %d state %d (%uus %s)\n", 187 data->count, data->state, ev.duration, TO_STR(ev.pulse)); 188 data->state = STATE_INACTIVE; 189 return -EINVAL; 190} 191 192static struct ir_raw_handler xmp_handler = { 193 .protocols = RC_PROTO_BIT_XMP, 194 .decode = ir_xmp_decode, 195 .min_timeout = XMP_TRAILER_SPACE, 196}; 197 198static int __init ir_xmp_decode_init(void) 199{ 200 ir_raw_handler_register(&xmp_handler); 201 202 printk(KERN_INFO "IR XMP protocol handler initialized\n"); 203 return 0; 204} 205 206static void __exit ir_xmp_decode_exit(void) 207{ 208 ir_raw_handler_unregister(&xmp_handler); 209} 210 211module_init(ir_xmp_decode_init); 212module_exit(ir_xmp_decode_exit); 213 214MODULE_LICENSE("GPL"); 215MODULE_AUTHOR("Marcel Mol <marcel@mesa.nl>"); 216MODULE_AUTHOR("MESA Consulting (http://www.mesa.nl)"); 217MODULE_DESCRIPTION("XMP IR protocol decoder"); 218