1 // SPDX-License-Identifier: GPL-2.0-only
2 /* ir-sharp-decoder.c - handle Sharp IR Pulse/Space protocol
3 *
4 * Copyright (C) 2013-2014 Imagination Technologies Ltd.
5 *
6 * Based on NEC decoder:
7 * Copyright (C) 2010 by Mauro Carvalho Chehab
8 */
9
10 #include <linux/bitrev.h>
11 #include <linux/module.h>
12 #include "rc-core-priv.h"
13
14 #define SHARP_NBITS 15
15 #define SHARP_UNIT 40000 /* ns */
16 #define SHARP_BIT_PULSE (8 * SHARP_UNIT) /* 320us */
17 #define SHARP_BIT_0_PERIOD (25 * SHARP_UNIT) /* 1ms (680us space) */
18 #define SHARP_BIT_1_PERIOD (50 * SHARP_UNIT) /* 2ms (1680ms space) */
19 #define SHARP_ECHO_SPACE (1000 * SHARP_UNIT) /* 40 ms */
20 #define SHARP_TRAILER_SPACE (125 * SHARP_UNIT) /* 5 ms (even longer) */
21
22 enum sharp_state {
23 STATE_INACTIVE,
24 STATE_BIT_PULSE,
25 STATE_BIT_SPACE,
26 STATE_TRAILER_PULSE,
27 STATE_ECHO_SPACE,
28 STATE_TRAILER_SPACE,
29 };
30
31 /**
32 * ir_sharp_decode() - Decode one Sharp pulse or space
33 * @dev: the struct rc_dev descriptor of the device
34 * @ev: the struct ir_raw_event descriptor of the pulse/space
35 *
36 * This function returns -EINVAL if the pulse violates the state machine
37 */
ir_sharp_decode(struct rc_dev * dev,struct ir_raw_event ev)38 static int ir_sharp_decode(struct rc_dev *dev, struct ir_raw_event ev)
39 {
40 struct sharp_dec *data = &dev->raw->sharp;
41 u32 msg, echo, address, command, scancode;
42
43 if (!is_timing_event(ev)) {
44 if (ev.reset)
45 data->state = STATE_INACTIVE;
46 return 0;
47 }
48
49 dev_dbg(&dev->dev, "Sharp decode started at state %d (%uus %s)\n",
50 data->state, TO_US(ev.duration), TO_STR(ev.pulse));
51
52 switch (data->state) {
53
54 case STATE_INACTIVE:
55 if (!ev.pulse)
56 break;
57
58 if (!eq_margin(ev.duration, SHARP_BIT_PULSE,
59 SHARP_BIT_PULSE / 2))
60 break;
61
62 data->count = 0;
63 data->pulse_len = ev.duration;
64 data->state = STATE_BIT_SPACE;
65 return 0;
66
67 case STATE_BIT_PULSE:
68 if (!ev.pulse)
69 break;
70
71 if (!eq_margin(ev.duration, SHARP_BIT_PULSE,
72 SHARP_BIT_PULSE / 2))
73 break;
74
75 data->pulse_len = ev.duration;
76 data->state = STATE_BIT_SPACE;
77 return 0;
78
79 case STATE_BIT_SPACE:
80 if (ev.pulse)
81 break;
82
83 data->bits <<= 1;
84 if (eq_margin(data->pulse_len + ev.duration, SHARP_BIT_1_PERIOD,
85 SHARP_BIT_PULSE * 2))
86 data->bits |= 1;
87 else if (!eq_margin(data->pulse_len + ev.duration,
88 SHARP_BIT_0_PERIOD, SHARP_BIT_PULSE * 2))
89 break;
90 data->count++;
91
92 if (data->count == SHARP_NBITS ||
93 data->count == SHARP_NBITS * 2)
94 data->state = STATE_TRAILER_PULSE;
95 else
96 data->state = STATE_BIT_PULSE;
97
98 return 0;
99
100 case STATE_TRAILER_PULSE:
101 if (!ev.pulse)
102 break;
103
104 if (!eq_margin(ev.duration, SHARP_BIT_PULSE,
105 SHARP_BIT_PULSE / 2))
106 break;
107
108 if (data->count == SHARP_NBITS) {
109 /* exp,chk bits should be 1,0 */
110 if ((data->bits & 0x3) != 0x2 &&
111 /* DENON variant, both chk bits 0 */
112 (data->bits & 0x3) != 0x0)
113 break;
114 data->state = STATE_ECHO_SPACE;
115 } else {
116 data->state = STATE_TRAILER_SPACE;
117 }
118 return 0;
119
120 case STATE_ECHO_SPACE:
121 if (ev.pulse)
122 break;
123
124 if (!eq_margin(ev.duration, SHARP_ECHO_SPACE,
125 SHARP_ECHO_SPACE / 4))
126 break;
127
128 data->state = STATE_BIT_PULSE;
129
130 return 0;
131
132 case STATE_TRAILER_SPACE:
133 if (ev.pulse)
134 break;
135
136 if (!geq_margin(ev.duration, SHARP_TRAILER_SPACE,
137 SHARP_BIT_PULSE / 2))
138 break;
139
140 /* Validate - command, ext, chk should be inverted in 2nd */
141 msg = (data->bits >> 15) & 0x7fff;
142 echo = data->bits & 0x7fff;
143 if ((msg ^ echo) != 0x3ff) {
144 dev_dbg(&dev->dev,
145 "Sharp checksum error: received 0x%04x, 0x%04x\n",
146 msg, echo);
147 break;
148 }
149
150 address = bitrev8((msg >> 7) & 0xf8);
151 command = bitrev8((msg >> 2) & 0xff);
152
153 scancode = address << 8 | command;
154 dev_dbg(&dev->dev, "Sharp scancode 0x%04x\n", scancode);
155
156 rc_keydown(dev, RC_PROTO_SHARP, scancode, 0);
157 data->state = STATE_INACTIVE;
158 return 0;
159 }
160
161 dev_dbg(&dev->dev, "Sharp decode failed at count %d state %d (%uus %s)\n",
162 data->count, data->state, TO_US(ev.duration), TO_STR(ev.pulse));
163 data->state = STATE_INACTIVE;
164 return -EINVAL;
165 }
166
167 static const struct ir_raw_timings_pd ir_sharp_timings = {
168 .header_pulse = 0,
169 .header_space = 0,
170 .bit_pulse = SHARP_BIT_PULSE,
171 .bit_space[0] = SHARP_BIT_0_PERIOD,
172 .bit_space[1] = SHARP_BIT_1_PERIOD,
173 .trailer_pulse = SHARP_BIT_PULSE,
174 .trailer_space = SHARP_ECHO_SPACE,
175 .msb_first = 1,
176 };
177
178 /**
179 * ir_sharp_encode() - Encode a scancode as a stream of raw events
180 *
181 * @protocol: protocol to encode
182 * @scancode: scancode to encode
183 * @events: array of raw ir events to write into
184 * @max: maximum size of @events
185 *
186 * Returns: The number of events written.
187 * -ENOBUFS if there isn't enough space in the array to fit the
188 * encoding. In this case all @max events will have been written.
189 */
ir_sharp_encode(enum rc_proto protocol,u32 scancode,struct ir_raw_event * events,unsigned int max)190 static int ir_sharp_encode(enum rc_proto protocol, u32 scancode,
191 struct ir_raw_event *events, unsigned int max)
192 {
193 struct ir_raw_event *e = events;
194 int ret;
195 u32 raw;
196
197 raw = (((bitrev8(scancode >> 8) >> 3) << 8) & 0x1f00) |
198 bitrev8(scancode);
199 ret = ir_raw_gen_pd(&e, max, &ir_sharp_timings, SHARP_NBITS,
200 (raw << 2) | 2);
201 if (ret < 0)
202 return ret;
203
204 max -= ret;
205
206 raw = (((bitrev8(scancode >> 8) >> 3) << 8) & 0x1f00) |
207 bitrev8(~scancode);
208 ret = ir_raw_gen_pd(&e, max, &ir_sharp_timings, SHARP_NBITS,
209 (raw << 2) | 1);
210 if (ret < 0)
211 return ret;
212
213 return e - events;
214 }
215
216 static struct ir_raw_handler sharp_handler = {
217 .protocols = RC_PROTO_BIT_SHARP,
218 .decode = ir_sharp_decode,
219 .encode = ir_sharp_encode,
220 .carrier = 38000,
221 .min_timeout = SHARP_ECHO_SPACE + SHARP_ECHO_SPACE / 4,
222 };
223
ir_sharp_decode_init(void)224 static int __init ir_sharp_decode_init(void)
225 {
226 ir_raw_handler_register(&sharp_handler);
227
228 pr_info("IR Sharp protocol handler initialized\n");
229 return 0;
230 }
231
ir_sharp_decode_exit(void)232 static void __exit ir_sharp_decode_exit(void)
233 {
234 ir_raw_handler_unregister(&sharp_handler);
235 }
236
237 module_init(ir_sharp_decode_init);
238 module_exit(ir_sharp_decode_exit);
239
240 MODULE_LICENSE("GPL");
241 MODULE_AUTHOR("James Hogan <jhogan@kernel.org>");
242 MODULE_DESCRIPTION("Sharp IR protocol decoder");
243
