1/* ir-rc5-decoder.c - decoder for RC5(x) and StreamZap protocols
2 *
3 * Copyright (C) 2010 by Mauro Carvalho Chehab
4 * Copyright (C) 2010 by Jarod Wilson <jarod@redhat.com>
5 *
6 * This program is free software; you can redistribute it and/or modify
7 *  it under the terms of the GNU General Public License as published by
8 *  the Free Software Foundation version 2 of the License.
9 *
10 *  This program is distributed in the hope that it will be useful,
11 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
12 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
13 *  GNU General Public License for more details.
14 */
15
16/*
17 * This decoder handles the 14 bit RC5 protocol, 15 bit "StreamZap" protocol
18 * and 20 bit RC5x protocol.
19 */
20
21#include "rc-core-priv.h"
22#include <linux/module.h>
23
24#define RC5_NBITS		14
25#define RC5_SZ_NBITS		15
26#define RC5X_NBITS		20
27#define CHECK_RC5X_NBITS	8
28#define RC5_UNIT		888888 /* ns */
29#define RC5_BIT_START		(1 * RC5_UNIT)
30#define RC5_BIT_END		(1 * RC5_UNIT)
31#define RC5X_SPACE		(4 * RC5_UNIT)
32#define RC5_TRAILER		(10 * RC5_UNIT) /* In reality, approx 100 */
33
34enum rc5_state {
35	STATE_INACTIVE,
36	STATE_BIT_START,
37	STATE_BIT_END,
38	STATE_CHECK_RC5X,
39	STATE_FINISHED,
40};
41
42/**
43 * ir_rc5_decode() - Decode one RC-5 pulse or space
44 * @dev:	the struct rc_dev descriptor of the device
45 * @ev:		the struct ir_raw_event descriptor of the pulse/space
46 *
47 * This function returns -EINVAL if the pulse violates the state machine
48 */
49static int ir_rc5_decode(struct rc_dev *dev, struct ir_raw_event ev)
50{
51	struct rc5_dec *data = &dev->raw->rc5;
52	u8 toggle;
53	u32 scancode;
54	enum rc_type protocol;
55
56	if (!(dev->enabled_protocols & (RC_BIT_RC5 | RC_BIT_RC5X | RC_BIT_RC5_SZ)))
57		return 0;
58
59	if (!is_timing_event(ev)) {
60		if (ev.reset)
61			data->state = STATE_INACTIVE;
62		return 0;
63	}
64
65	if (!geq_margin(ev.duration, RC5_UNIT, RC5_UNIT / 2))
66		goto out;
67
68again:
69	IR_dprintk(2, "RC5(x/sz) decode started at state %i (%uus %s)\n",
70		   data->state, TO_US(ev.duration), TO_STR(ev.pulse));
71
72	if (!geq_margin(ev.duration, RC5_UNIT, RC5_UNIT / 2))
73		return 0;
74
75	switch (data->state) {
76
77	case STATE_INACTIVE:
78		if (!ev.pulse)
79			break;
80
81		data->state = STATE_BIT_START;
82		data->count = 1;
83		decrease_duration(&ev, RC5_BIT_START);
84		goto again;
85
86	case STATE_BIT_START:
87		if (!ev.pulse && geq_margin(ev.duration, RC5_TRAILER, RC5_UNIT / 2)) {
88			data->state = STATE_FINISHED;
89			goto again;
90		}
91
92		if (!eq_margin(ev.duration, RC5_BIT_START, RC5_UNIT / 2))
93			break;
94
95		data->bits <<= 1;
96		if (!ev.pulse)
97			data->bits |= 1;
98		data->count++;
99		data->state = STATE_BIT_END;
100		return 0;
101
102	case STATE_BIT_END:
103		if (!is_transition(&ev, &dev->raw->prev_ev))
104			break;
105
106		if (data->count == CHECK_RC5X_NBITS)
107			data->state = STATE_CHECK_RC5X;
108		else
109			data->state = STATE_BIT_START;
110
111		decrease_duration(&ev, RC5_BIT_END);
112		goto again;
113
114	case STATE_CHECK_RC5X:
115		if (!ev.pulse && geq_margin(ev.duration, RC5X_SPACE, RC5_UNIT / 2)) {
116			data->is_rc5x = true;
117			decrease_duration(&ev, RC5X_SPACE);
118		} else
119			data->is_rc5x = false;
120		data->state = STATE_BIT_START;
121		goto again;
122
123	case STATE_FINISHED:
124		if (ev.pulse)
125			break;
126
127		if (data->is_rc5x && data->count == RC5X_NBITS) {
128			/* RC5X */
129			u8 xdata, command, system;
130			if (!(dev->enabled_protocols & RC_BIT_RC5X)) {
131				data->state = STATE_INACTIVE;
132				return 0;
133			}
134			xdata    = (data->bits & 0x0003F) >> 0;
135			command  = (data->bits & 0x00FC0) >> 6;
136			system   = (data->bits & 0x1F000) >> 12;
137			toggle   = (data->bits & 0x20000) ? 1 : 0;
138			command += (data->bits & 0x01000) ? 0 : 0x40;
139			scancode = system << 16 | command << 8 | xdata;
140			protocol = RC_TYPE_RC5X;
141
142		} else if (!data->is_rc5x && data->count == RC5_NBITS) {
143			/* RC5 */
144			u8 command, system;
145			if (!(dev->enabled_protocols & RC_BIT_RC5)) {
146				data->state = STATE_INACTIVE;
147				return 0;
148			}
149			command  = (data->bits & 0x0003F) >> 0;
150			system   = (data->bits & 0x007C0) >> 6;
151			toggle   = (data->bits & 0x00800) ? 1 : 0;
152			command += (data->bits & 0x01000) ? 0 : 0x40;
153			scancode = system << 8 | command;
154			protocol = RC_TYPE_RC5;
155
156		} else if (!data->is_rc5x && data->count == RC5_SZ_NBITS) {
157			/* RC5 StreamZap */
158			u8 command, system;
159			if (!(dev->enabled_protocols & RC_BIT_RC5_SZ)) {
160				data->state = STATE_INACTIVE;
161				return 0;
162			}
163			command  = (data->bits & 0x0003F) >> 0;
164			system   = (data->bits & 0x02FC0) >> 6;
165			toggle   = (data->bits & 0x01000) ? 1 : 0;
166			scancode = system << 6 | command;
167			protocol = RC_TYPE_RC5_SZ;
168
169		} else
170			break;
171
172		IR_dprintk(1, "RC5(x/sz) scancode 0x%06x (p: %u, t: %u)\n",
173			   scancode, protocol, toggle);
174
175		rc_keydown(dev, protocol, scancode, toggle);
176		data->state = STATE_INACTIVE;
177		return 0;
178	}
179
180out:
181	IR_dprintk(1, "RC5(x/sz) decode failed at state %i count %d (%uus %s)\n",
182		   data->state, data->count, TO_US(ev.duration), TO_STR(ev.pulse));
183	data->state = STATE_INACTIVE;
184	return -EINVAL;
185}
186
187static struct ir_raw_handler rc5_handler = {
188	.protocols	= RC_BIT_RC5 | RC_BIT_RC5X | RC_BIT_RC5_SZ,
189	.decode		= ir_rc5_decode,
190};
191
192static int __init ir_rc5_decode_init(void)
193{
194	ir_raw_handler_register(&rc5_handler);
195
196	printk(KERN_INFO "IR RC5(x/sz) protocol handler initialized\n");
197	return 0;
198}
199
200static void __exit ir_rc5_decode_exit(void)
201{
202	ir_raw_handler_unregister(&rc5_handler);
203}
204
205module_init(ir_rc5_decode_init);
206module_exit(ir_rc5_decode_exit);
207
208MODULE_LICENSE("GPL");
209MODULE_AUTHOR("Mauro Carvalho Chehab and Jarod Wilson");
210MODULE_AUTHOR("Red Hat Inc. (http://www.redhat.com)");
211MODULE_DESCRIPTION("RC5(x/sz) IR protocol decoder");
212