1 // SPDX-License-Identifier: GPL-2.0
2 // ir-rc5-decoder.c - decoder for RC5(x) and StreamZap protocols
3 //
4 // Copyright (C) 2010 by Mauro Carvalho Chehab
5 // Copyright (C) 2010 by Jarod Wilson <jarod@redhat.com>
6
7 /*
8 * This decoder handles the 14 bit RC5 protocol, 15 bit "StreamZap" protocol
9 * and 20 bit RC5x protocol.
10 */
11
12 #include "rc-core-priv.h"
13 #include <linux/module.h>
14
15 #define RC5_NBITS 14
16 #define RC5_SZ_NBITS 15
17 #define RC5X_NBITS 20
18 #define CHECK_RC5X_NBITS 8
19 #define RC5_UNIT 889 /* us */
20 #define RC5_BIT_START (1 * RC5_UNIT)
21 #define RC5_BIT_END (1 * RC5_UNIT)
22 #define RC5X_SPACE (4 * RC5_UNIT)
23 #define RC5_TRAILER (6 * RC5_UNIT) /* In reality, approx 100 */
24
25 enum rc5_state {
26 STATE_INACTIVE,
27 STATE_BIT_START,
28 STATE_BIT_END,
29 STATE_CHECK_RC5X,
30 STATE_FINISHED,
31 };
32
33 /**
34 * ir_rc5_decode() - Decode one RC-5 pulse or space
35 * @dev: the struct rc_dev descriptor of the device
36 * @ev: the struct ir_raw_event descriptor of the pulse/space
37 *
38 * This function returns -EINVAL if the pulse violates the state machine
39 */
ir_rc5_decode(struct rc_dev * dev,struct ir_raw_event ev)40 static int ir_rc5_decode(struct rc_dev *dev, struct ir_raw_event ev)
41 {
42 struct rc5_dec *data = &dev->raw->rc5;
43 u8 toggle;
44 u32 scancode;
45 enum rc_proto protocol;
46
47 if (!is_timing_event(ev)) {
48 if (ev.overflow)
49 data->state = STATE_INACTIVE;
50 return 0;
51 }
52
53 if (!geq_margin(ev.duration, RC5_UNIT, RC5_UNIT / 2))
54 goto out;
55
56 again:
57 dev_dbg(&dev->dev, "RC5(x/sz) decode started at state %i (%uus %s)\n",
58 data->state, ev.duration, TO_STR(ev.pulse));
59
60 if (!geq_margin(ev.duration, RC5_UNIT, RC5_UNIT / 2))
61 return 0;
62
63 switch (data->state) {
64
65 case STATE_INACTIVE:
66 if (!ev.pulse)
67 break;
68
69 data->state = STATE_BIT_START;
70 data->count = 1;
71 decrease_duration(&ev, RC5_BIT_START);
72 goto again;
73
74 case STATE_BIT_START:
75 if (!ev.pulse && geq_margin(ev.duration, RC5_TRAILER, RC5_UNIT / 2)) {
76 data->state = STATE_FINISHED;
77 goto again;
78 }
79
80 if (!eq_margin(ev.duration, RC5_BIT_START, RC5_UNIT / 2))
81 break;
82
83 data->bits <<= 1;
84 if (!ev.pulse)
85 data->bits |= 1;
86 data->count++;
87 data->state = STATE_BIT_END;
88 return 0;
89
90 case STATE_BIT_END:
91 if (data->count == CHECK_RC5X_NBITS)
92 data->state = STATE_CHECK_RC5X;
93 else
94 data->state = STATE_BIT_START;
95
96 decrease_duration(&ev, RC5_BIT_END);
97 goto again;
98
99 case STATE_CHECK_RC5X:
100 if (!ev.pulse && geq_margin(ev.duration, RC5X_SPACE, RC5_UNIT / 2)) {
101 data->is_rc5x = true;
102 decrease_duration(&ev, RC5X_SPACE);
103 } else
104 data->is_rc5x = false;
105 data->state = STATE_BIT_START;
106 goto again;
107
108 case STATE_FINISHED:
109 if (ev.pulse)
110 break;
111
112 if (data->is_rc5x && data->count == RC5X_NBITS) {
113 /* RC5X */
114 u8 xdata, command, system;
115 if (!(dev->enabled_protocols & RC_PROTO_BIT_RC5X_20)) {
116 data->state = STATE_INACTIVE;
117 return 0;
118 }
119 xdata = (data->bits & 0x0003F) >> 0;
120 command = (data->bits & 0x00FC0) >> 6;
121 system = (data->bits & 0x1F000) >> 12;
122 toggle = (data->bits & 0x20000) ? 1 : 0;
123 command += (data->bits & 0x40000) ? 0 : 0x40;
124 scancode = system << 16 | command << 8 | xdata;
125 protocol = RC_PROTO_RC5X_20;
126
127 } else if (!data->is_rc5x && data->count == RC5_NBITS) {
128 /* RC5 */
129 u8 command, system;
130 if (!(dev->enabled_protocols & RC_PROTO_BIT_RC5)) {
131 data->state = STATE_INACTIVE;
132 return 0;
133 }
134 command = (data->bits & 0x0003F) >> 0;
135 system = (data->bits & 0x007C0) >> 6;
136 toggle = (data->bits & 0x00800) ? 1 : 0;
137 command += (data->bits & 0x01000) ? 0 : 0x40;
138 scancode = system << 8 | command;
139 protocol = RC_PROTO_RC5;
140
141 } else if (!data->is_rc5x && data->count == RC5_SZ_NBITS) {
142 /* RC5 StreamZap */
143 u8 command, system;
144 if (!(dev->enabled_protocols & RC_PROTO_BIT_RC5_SZ)) {
145 data->state = STATE_INACTIVE;
146 return 0;
147 }
148 command = (data->bits & 0x0003F) >> 0;
149 system = (data->bits & 0x02FC0) >> 6;
150 toggle = (data->bits & 0x01000) ? 1 : 0;
151 scancode = system << 6 | command;
152 protocol = RC_PROTO_RC5_SZ;
153
154 } else
155 break;
156
157 dev_dbg(&dev->dev, "RC5(x/sz) scancode 0x%06x (p: %u, t: %u)\n",
158 scancode, protocol, toggle);
159
160 rc_keydown(dev, protocol, scancode, toggle);
161 data->state = STATE_INACTIVE;
162 return 0;
163 }
164
165 out:
166 dev_dbg(&dev->dev, "RC5(x/sz) decode failed at state %i count %d (%uus %s)\n",
167 data->state, data->count, ev.duration, TO_STR(ev.pulse));
168 data->state = STATE_INACTIVE;
169 return -EINVAL;
170 }
171
172 static const struct ir_raw_timings_manchester ir_rc5_timings = {
173 .leader_pulse = RC5_UNIT,
174 .clock = RC5_UNIT,
175 .trailer_space = RC5_UNIT * 10,
176 };
177
178 static const struct ir_raw_timings_manchester ir_rc5x_timings[2] = {
179 {
180 .leader_pulse = RC5_UNIT,
181 .clock = RC5_UNIT,
182 .trailer_space = RC5X_SPACE,
183 },
184 {
185 .clock = RC5_UNIT,
186 .trailer_space = RC5_UNIT * 10,
187 },
188 };
189
190 static const struct ir_raw_timings_manchester ir_rc5_sz_timings = {
191 .leader_pulse = RC5_UNIT,
192 .clock = RC5_UNIT,
193 .trailer_space = RC5_UNIT * 10,
194 };
195
196 /**
197 * ir_rc5_encode() - Encode a scancode as a stream of raw events
198 *
199 * @protocol: protocol variant to encode
200 * @scancode: scancode to encode
201 * @events: array of raw ir events to write into
202 * @max: maximum size of @events
203 *
204 * Returns: The number of events written.
205 * -ENOBUFS if there isn't enough space in the array to fit the
206 * encoding. In this case all @max events will have been written.
207 * -EINVAL if the scancode is ambiguous or invalid.
208 */
ir_rc5_encode(enum rc_proto protocol,u32 scancode,struct ir_raw_event * events,unsigned int max)209 static int ir_rc5_encode(enum rc_proto protocol, u32 scancode,
210 struct ir_raw_event *events, unsigned int max)
211 {
212 int ret;
213 struct ir_raw_event *e = events;
214 unsigned int data, xdata, command, commandx, system, pre_space_data;
215
216 /* Detect protocol and convert scancode to raw data */
217 if (protocol == RC_PROTO_RC5) {
218 /* decode scancode */
219 command = (scancode & 0x003f) >> 0;
220 commandx = (scancode & 0x0040) >> 6;
221 system = (scancode & 0x1f00) >> 8;
222 /* encode data */
223 data = !commandx << 12 | system << 6 | command;
224
225 /* First bit is encoded by leader_pulse */
226 ret = ir_raw_gen_manchester(&e, max, &ir_rc5_timings,
227 RC5_NBITS - 1, data);
228 if (ret < 0)
229 return ret;
230 } else if (protocol == RC_PROTO_RC5X_20) {
231 /* decode scancode */
232 xdata = (scancode & 0x00003f) >> 0;
233 command = (scancode & 0x003f00) >> 8;
234 commandx = !(scancode & 0x004000);
235 system = (scancode & 0x1f0000) >> 16;
236
237 /* encode data */
238 data = commandx << 18 | system << 12 | command << 6 | xdata;
239
240 /* First bit is encoded by leader_pulse */
241 pre_space_data = data >> (RC5X_NBITS - CHECK_RC5X_NBITS);
242 ret = ir_raw_gen_manchester(&e, max, &ir_rc5x_timings[0],
243 CHECK_RC5X_NBITS - 1,
244 pre_space_data);
245 if (ret < 0)
246 return ret;
247 ret = ir_raw_gen_manchester(&e, max - (e - events),
248 &ir_rc5x_timings[1],
249 RC5X_NBITS - CHECK_RC5X_NBITS,
250 data);
251 if (ret < 0)
252 return ret;
253 } else if (protocol == RC_PROTO_RC5_SZ) {
254 /* RC5-SZ scancode is raw enough for Manchester as it is */
255 /* First bit is encoded by leader_pulse */
256 ret = ir_raw_gen_manchester(&e, max, &ir_rc5_sz_timings,
257 RC5_SZ_NBITS - 1,
258 scancode & 0x2fff);
259 if (ret < 0)
260 return ret;
261 } else {
262 return -EINVAL;
263 }
264
265 return e - events;
266 }
267
268 static struct ir_raw_handler rc5_handler = {
269 .protocols = RC_PROTO_BIT_RC5 | RC_PROTO_BIT_RC5X_20 |
270 RC_PROTO_BIT_RC5_SZ,
271 .decode = ir_rc5_decode,
272 .encode = ir_rc5_encode,
273 .carrier = 36000,
274 .min_timeout = RC5_TRAILER,
275 };
276
ir_rc5_decode_init(void)277 static int __init ir_rc5_decode_init(void)
278 {
279 ir_raw_handler_register(&rc5_handler);
280
281 printk(KERN_INFO "IR RC5(x/sz) protocol handler initialized\n");
282 return 0;
283 }
284
ir_rc5_decode_exit(void)285 static void __exit ir_rc5_decode_exit(void)
286 {
287 ir_raw_handler_unregister(&rc5_handler);
288 }
289
290 module_init(ir_rc5_decode_init);
291 module_exit(ir_rc5_decode_exit);
292
293 MODULE_LICENSE("GPL v2");
294 MODULE_AUTHOR("Mauro Carvalho Chehab and Jarod Wilson");
295 MODULE_AUTHOR("Red Hat Inc. (http://www.redhat.com)");
296 MODULE_DESCRIPTION("RC5(x/sz) IR protocol decoder");
297