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 40 /* us */ 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 */ 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, 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, 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 */ 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 }; 223 224 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 } 231 232 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