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(d1: 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(d1: 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(d1: 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, protocol: RC_PROTO_XMP, scancode, toggle: 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(d1: 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(d1: 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(ir_raw_handler: &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(ir_raw_handler: &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

source code of linux/drivers/media/rc/ir-xmp-decoder.c