1 /* ir-xmp-decoder.c - handle XMP IR Pulse/Space protocol
2  *
3  * Copyright (C) 2014 by Marcel Mol
4  *
5  * This program is free software; you can redistribute it and/or modify
6  *  it under the terms of the GNU General Public License as published by
7  *  the Free Software Foundation version 2 of the License.
8  *
9  *  This program is distributed in the hope that it will be useful,
10  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
11  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
12  *  GNU General Public License for more details.
13  *
14  * - Based on info from http://www.hifi-remote.com
15  * - Ignore Toggle=9 frames
16  * - Ignore XMP-1 XMP-2 difference, always store 16 bit OBC
17  */
18 
19 #include <linux/bitrev.h>
20 #include <linux/module.h>
21 #include "rc-core-priv.h"
22 
23 #define XMP_UNIT		  136000 /* ns */
24 #define XMP_LEADER		  210000 /* ns */
25 #define XMP_NIBBLE_PREFIX	  760000 /* ns */
26 #define	XMP_HALFFRAME_SPACE	13800000 /* ns */
27 #define	XMP_TRAILER_SPACE	20000000 /* should be 80ms but not all dureation supliers can go that high */
28 
29 enum xmp_state {
30 	STATE_INACTIVE,
31 	STATE_LEADER_PULSE,
32 	STATE_NIBBLE_SPACE,
33 };
34 
35 /**
36  * ir_xmp_decode() - Decode one XMP pulse or space
37  * @dev:	the struct rc_dev descriptor of the device
38  * @ev:		the struct ir_raw_event descriptor of the pulse/space
39  *
40  * This function returns -EINVAL if the pulse violates the state machine
41  */
42 static int ir_xmp_decode(struct rc_dev *dev, struct ir_raw_event ev)
43 {
44 	struct xmp_dec *data = &dev->raw->xmp;
45 
46 	if (!is_timing_event(ev)) {
47 		if (ev.reset)
48 			data->state = STATE_INACTIVE;
49 		return 0;
50 	}
51 
52 	dev_dbg(&dev->dev, "XMP decode started at state %d %d (%uus %s)\n",
53 		data->state, data->count, TO_US(ev.duration), TO_STR(ev.pulse));
54 
55 	switch (data->state) {
56 
57 	case STATE_INACTIVE:
58 		if (!ev.pulse)
59 			break;
60 
61 		if (eq_margin(ev.duration, XMP_LEADER, XMP_UNIT / 2)) {
62 			data->count = 0;
63 			data->state = STATE_NIBBLE_SPACE;
64 		}
65 
66 		return 0;
67 
68 	case STATE_LEADER_PULSE:
69 		if (!ev.pulse)
70 			break;
71 
72 		if (eq_margin(ev.duration, XMP_LEADER, XMP_UNIT / 2))
73 			data->state = STATE_NIBBLE_SPACE;
74 
75 		return 0;
76 
77 	case STATE_NIBBLE_SPACE:
78 		if (ev.pulse)
79 			break;
80 
81 		if (geq_margin(ev.duration, XMP_TRAILER_SPACE, XMP_NIBBLE_PREFIX)) {
82 			int divider, i;
83 			u8 addr, subaddr, subaddr2, toggle, oem, obc1, obc2, sum1, sum2;
84 			u32 *n;
85 			u32 scancode;
86 
87 			if (data->count != 16) {
88 				dev_dbg(&dev->dev, "received TRAILER period at index %d: %u\n",
89 					data->count, ev.duration);
90 				data->state = STATE_INACTIVE;
91 				return -EINVAL;
92 			}
93 
94 			n = data->durations;
95 			/*
96 			 * the 4th nibble should be 15 so base the divider on this
97 			 * to transform durations into nibbles. Substract 2000 from
98 			 * the divider to compensate for fluctuations in the signal
99 			 */
100 			divider = (n[3] - XMP_NIBBLE_PREFIX) / 15 - 2000;
101 			if (divider < 50) {
102 				dev_dbg(&dev->dev, "divider to small %d.\n",
103 					divider);
104 				data->state = STATE_INACTIVE;
105 				return -EINVAL;
106 			}
107 
108 			/* convert to nibbles and do some sanity checks */
109 			for (i = 0; i < 16; i++)
110 				n[i] = (n[i] - XMP_NIBBLE_PREFIX) / divider;
111 			sum1 = (15 + n[0] + n[1] + n[2] + n[3] +
112 				n[4] + n[5] + n[6] + n[7]) % 16;
113 			sum2 = (15 + n[8] + n[9] + n[10] + n[11] +
114 				n[12] + n[13] + n[14] + n[15]) % 16;
115 
116 			if (sum1 != 15 || sum2 != 15) {
117 				dev_dbg(&dev->dev, "checksum errors sum1=0x%X sum2=0x%X\n",
118 					sum1, sum2);
119 				data->state = STATE_INACTIVE;
120 				return -EINVAL;
121 			}
122 
123 			subaddr  = n[0] << 4 | n[2];
124 			subaddr2 = n[8] << 4 | n[11];
125 			oem      = n[4] << 4 | n[5];
126 			addr     = n[6] << 4 | n[7];
127 			toggle   = n[10];
128 			obc1 = n[12] << 4 | n[13];
129 			obc2 = n[14] << 4 | n[15];
130 			if (subaddr != subaddr2) {
131 				dev_dbg(&dev->dev, "subaddress nibbles mismatch 0x%02X != 0x%02X\n",
132 					subaddr, subaddr2);
133 				data->state = STATE_INACTIVE;
134 				return -EINVAL;
135 			}
136 			if (oem != 0x44)
137 				dev_dbg(&dev->dev, "Warning: OEM nibbles 0x%02X. Expected 0x44\n",
138 					oem);
139 
140 			scancode = addr << 24 | subaddr << 16 |
141 				   obc1 << 8 | obc2;
142 			dev_dbg(&dev->dev, "XMP scancode 0x%06x\n", scancode);
143 
144 			if (toggle == 0) {
145 				rc_keydown(dev, RC_PROTO_XMP, scancode, 0);
146 			} else {
147 				rc_repeat(dev);
148 				dev_dbg(&dev->dev, "Repeat last key\n");
149 			}
150 			data->state = STATE_INACTIVE;
151 
152 			return 0;
153 
154 		} else if (geq_margin(ev.duration, XMP_HALFFRAME_SPACE, XMP_NIBBLE_PREFIX)) {
155 			/* Expect 8 or 16 nibble pulses. 16 in case of 'final' frame */
156 			if (data->count == 16) {
157 				dev_dbg(&dev->dev, "received half frame pulse at index %d. Probably a final frame key-up event: %u\n",
158 					data->count, ev.duration);
159 				/*
160 				 * TODO: for now go back to half frame position
161 				 *	 so trailer can be found and key press
162 				 *	 can be handled.
163 				 */
164 				data->count = 8;
165 			}
166 
167 			else if (data->count != 8)
168 				dev_dbg(&dev->dev, "received half frame pulse at index %d: %u\n",
169 					data->count, ev.duration);
170 			data->state = STATE_LEADER_PULSE;
171 
172 			return 0;
173 
174 		} else if (geq_margin(ev.duration, XMP_NIBBLE_PREFIX, XMP_UNIT)) {
175 			/* store nibble raw data, decode after trailer */
176 			if (data->count == 16) {
177 				dev_dbg(&dev->dev, "to many pulses (%d) ignoring: %u\n",
178 					data->count, ev.duration);
179 				data->state = STATE_INACTIVE;
180 				return -EINVAL;
181 			}
182 			data->durations[data->count] = ev.duration;
183 			data->count++;
184 			data->state = STATE_LEADER_PULSE;
185 
186 			return 0;
187 
188 		}
189 
190 		break;
191 	}
192 
193 	dev_dbg(&dev->dev, "XMP decode failed at count %d state %d (%uus %s)\n",
194 		data->count, data->state, TO_US(ev.duration), TO_STR(ev.pulse));
195 	data->state = STATE_INACTIVE;
196 	return -EINVAL;
197 }
198 
199 static struct ir_raw_handler xmp_handler = {
200 	.protocols	= RC_PROTO_BIT_XMP,
201 	.decode		= ir_xmp_decode,
202 	.min_timeout	= XMP_TRAILER_SPACE,
203 };
204 
205 static int __init ir_xmp_decode_init(void)
206 {
207 	ir_raw_handler_register(&xmp_handler);
208 
209 	printk(KERN_INFO "IR XMP protocol handler initialized\n");
210 	return 0;
211 }
212 
213 static void __exit ir_xmp_decode_exit(void)
214 {
215 	ir_raw_handler_unregister(&xmp_handler);
216 }
217 
218 module_init(ir_xmp_decode_init);
219 module_exit(ir_xmp_decode_exit);
220 
221 MODULE_LICENSE("GPL");
222 MODULE_AUTHOR("Marcel Mol <marcel@mesa.nl>");
223 MODULE_AUTHOR("MESA Consulting (http://www.mesa.nl)");
224 MODULE_DESCRIPTION("XMP IR protocol decoder");
225