1 /* ir-sharp-decoder.c - handle Sharp IR Pulse/Space protocol 2 * 3 * Copyright (C) 2013-2014 Imagination Technologies Ltd. 4 * 5 * Based on NEC decoder: 6 * Copyright (C) 2010 by Mauro Carvalho Chehab 7 * 8 * This program is free software; you can redistribute it and/or modify 9 * it under the terms of the GNU General Public License as published by 10 * the Free Software Foundation version 2 of the License. 11 * 12 * This program is distributed in the hope that it will be useful, 13 * but WITHOUT ANY WARRANTY; without even the implied warranty of 14 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 15 * GNU General Public License for more details. 16 */ 17 18 #include <linux/bitrev.h> 19 #include <linux/module.h> 20 #include "rc-core-priv.h" 21 22 #define SHARP_NBITS 15 23 #define SHARP_UNIT 40000 /* ns */ 24 #define SHARP_BIT_PULSE (8 * SHARP_UNIT) /* 320us */ 25 #define SHARP_BIT_0_PERIOD (25 * SHARP_UNIT) /* 1ms (680us space) */ 26 #define SHARP_BIT_1_PERIOD (50 * SHARP_UNIT) /* 2ms (1680ms space) */ 27 #define SHARP_ECHO_SPACE (1000 * SHARP_UNIT) /* 40 ms */ 28 #define SHARP_TRAILER_SPACE (125 * SHARP_UNIT) /* 5 ms (even longer) */ 29 30 enum sharp_state { 31 STATE_INACTIVE, 32 STATE_BIT_PULSE, 33 STATE_BIT_SPACE, 34 STATE_TRAILER_PULSE, 35 STATE_ECHO_SPACE, 36 STATE_TRAILER_SPACE, 37 }; 38 39 /** 40 * ir_sharp_decode() - Decode one Sharp pulse or space 41 * @dev: the struct rc_dev descriptor of the device 42 * @duration: the struct ir_raw_event descriptor of the pulse/space 43 * 44 * This function returns -EINVAL if the pulse violates the state machine 45 */ 46 static int ir_sharp_decode(struct rc_dev *dev, struct ir_raw_event ev) 47 { 48 struct sharp_dec *data = &dev->raw->sharp; 49 u32 msg, echo, address, command, scancode; 50 51 if (!is_timing_event(ev)) { 52 if (ev.reset) 53 data->state = STATE_INACTIVE; 54 return 0; 55 } 56 57 IR_dprintk(2, "Sharp decode started at state %d (%uus %s)\n", 58 data->state, TO_US(ev.duration), TO_STR(ev.pulse)); 59 60 switch (data->state) { 61 62 case STATE_INACTIVE: 63 if (!ev.pulse) 64 break; 65 66 if (!eq_margin(ev.duration, SHARP_BIT_PULSE, 67 SHARP_BIT_PULSE / 2)) 68 break; 69 70 data->count = 0; 71 data->pulse_len = ev.duration; 72 data->state = STATE_BIT_SPACE; 73 return 0; 74 75 case STATE_BIT_PULSE: 76 if (!ev.pulse) 77 break; 78 79 if (!eq_margin(ev.duration, SHARP_BIT_PULSE, 80 SHARP_BIT_PULSE / 2)) 81 break; 82 83 data->pulse_len = ev.duration; 84 data->state = STATE_BIT_SPACE; 85 return 0; 86 87 case STATE_BIT_SPACE: 88 if (ev.pulse) 89 break; 90 91 data->bits <<= 1; 92 if (eq_margin(data->pulse_len + ev.duration, SHARP_BIT_1_PERIOD, 93 SHARP_BIT_PULSE * 2)) 94 data->bits |= 1; 95 else if (!eq_margin(data->pulse_len + ev.duration, 96 SHARP_BIT_0_PERIOD, SHARP_BIT_PULSE * 2)) 97 break; 98 data->count++; 99 100 if (data->count == SHARP_NBITS || 101 data->count == SHARP_NBITS * 2) 102 data->state = STATE_TRAILER_PULSE; 103 else 104 data->state = STATE_BIT_PULSE; 105 106 return 0; 107 108 case STATE_TRAILER_PULSE: 109 if (!ev.pulse) 110 break; 111 112 if (!eq_margin(ev.duration, SHARP_BIT_PULSE, 113 SHARP_BIT_PULSE / 2)) 114 break; 115 116 if (data->count == SHARP_NBITS) { 117 /* exp,chk bits should be 1,0 */ 118 if ((data->bits & 0x3) != 0x2 && 119 /* DENON variant, both chk bits 0 */ 120 (data->bits & 0x3) != 0x0) 121 break; 122 data->state = STATE_ECHO_SPACE; 123 } else { 124 data->state = STATE_TRAILER_SPACE; 125 } 126 return 0; 127 128 case STATE_ECHO_SPACE: 129 if (ev.pulse) 130 break; 131 132 if (!eq_margin(ev.duration, SHARP_ECHO_SPACE, 133 SHARP_ECHO_SPACE / 4)) 134 break; 135 136 data->state = STATE_BIT_PULSE; 137 138 return 0; 139 140 case STATE_TRAILER_SPACE: 141 if (ev.pulse) 142 break; 143 144 if (!geq_margin(ev.duration, SHARP_TRAILER_SPACE, 145 SHARP_BIT_PULSE / 2)) 146 break; 147 148 /* Validate - command, ext, chk should be inverted in 2nd */ 149 msg = (data->bits >> 15) & 0x7fff; 150 echo = data->bits & 0x7fff; 151 if ((msg ^ echo) != 0x3ff) { 152 IR_dprintk(1, 153 "Sharp checksum error: received 0x%04x, 0x%04x\n", 154 msg, echo); 155 break; 156 } 157 158 address = bitrev8((msg >> 7) & 0xf8); 159 command = bitrev8((msg >> 2) & 0xff); 160 161 scancode = address << 8 | command; 162 IR_dprintk(1, "Sharp scancode 0x%04x\n", scancode); 163 164 rc_keydown(dev, RC_TYPE_SHARP, scancode, 0); 165 data->state = STATE_INACTIVE; 166 return 0; 167 } 168 169 IR_dprintk(1, "Sharp decode failed at count %d state %d (%uus %s)\n", 170 data->count, data->state, TO_US(ev.duration), 171 TO_STR(ev.pulse)); 172 data->state = STATE_INACTIVE; 173 return -EINVAL; 174 } 175 176 static struct ir_raw_handler sharp_handler = { 177 .protocols = RC_BIT_SHARP, 178 .decode = ir_sharp_decode, 179 }; 180 181 static int __init ir_sharp_decode_init(void) 182 { 183 ir_raw_handler_register(&sharp_handler); 184 185 pr_info("IR Sharp protocol handler initialized\n"); 186 return 0; 187 } 188 189 static void __exit ir_sharp_decode_exit(void) 190 { 191 ir_raw_handler_unregister(&sharp_handler); 192 } 193 194 module_init(ir_sharp_decode_init); 195 module_exit(ir_sharp_decode_exit); 196 197 MODULE_LICENSE("GPL"); 198 MODULE_AUTHOR("James Hogan <james.hogan@imgtec.com>"); 199 MODULE_DESCRIPTION("Sharp IR protocol decoder"); 200