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   1 /* ir-nec-decoder.c - handle NEC IR Pulse/Space protocol
   2  *
   3  * Copyright (C) 2010 by Mauro Carvalho Chehab <mchehab@redhat.com>
   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
  15 #include <linux/bitrev.h>
  16 #include "ir-core-priv.h"
  17
  18 #define NEC_NBITS               32
  19 #define NEC_UNIT                562500  /* ns */
  20 #define NEC_HEADER_PULSE        (16 * NEC_UNIT)
  21 #define NECX_HEADER_PULSE       (8  * NEC_UNIT) /* Less common NEC variant */
  22 #define NEC_HEADER_SPACE        (8  * NEC_UNIT)
  23 #define NEC_REPEAT_SPACE        (8  * NEC_UNIT)
  24 #define NEC_BIT_PULSE           (1  * NEC_UNIT)
  25 #define NEC_BIT_0_SPACE         (1  * NEC_UNIT)
  26 #define NEC_BIT_1_SPACE         (3  * NEC_UNIT)
  27 #define NEC_TRAILER_PULSE       (1  * NEC_UNIT)
  28 #define NEC_TRAILER_SPACE       (10 * NEC_UNIT) /* even longer in reality */
  29
  30 /* Used to register nec_decoder clients */
  31 static LIST_HEAD(decoder_list);
  32 static DEFINE_SPINLOCK(decoder_lock);
  33
  34 enum nec_state {
  35         STATE_INACTIVE,
  36         STATE_HEADER_SPACE,
  37         STATE_BIT_PULSE,
  38         STATE_BIT_SPACE,
  39         STATE_TRAILER_PULSE,
  40         STATE_TRAILER_SPACE,
  41 };
  42
  43 struct decoder_data {
  44         struct list_head        list;
  45         struct ir_input_dev     *ir_dev;
  46         int                     enabled:1;
  47
  48         /* State machine control */
  49         enum nec_state          state;
  50         u32                     nec_bits;
  51         unsigned                count;
  52 };
  53
  54
  55 /**
  56  * get_decoder_data()   - gets decoder data
  57  * @input_dev:  input device
  58  *
  59  * Returns the struct decoder_data that corresponds to a device
  60  */
  61 static struct decoder_data *get_decoder_data(struct  ir_input_dev *ir_dev)
  62 {
  63         struct decoder_data *data = NULL;
  64
  65         spin_lock(&decoder_lock);
  66         list_for_each_entry(data, &decoder_list, list) {
  67                 if (data->ir_dev == ir_dev)
  68                         break;
  69         }
  70         spin_unlock(&decoder_lock);
  71         return data;
  72 }
  73
  74 static ssize_t store_enabled(struct device *d,
  75                              struct device_attribute *mattr,
  76                              const char *buf,
  77                              size_t len)
  78 {
  79         unsigned long value;
  80         struct ir_input_dev *ir_dev = dev_get_drvdata(d);
  81         struct decoder_data *data = get_decoder_data(ir_dev);
  82
  83         if (!data)
  84                 return -EINVAL;
  85
  86         if (strict_strtoul(buf, 10, &value) || value > 1)
  87                 return -EINVAL;
  88
  89         data->enabled = value;
  90
  91         return len;
  92 }
  93
  94 static ssize_t show_enabled(struct device *d,
  95                              struct device_attribute *mattr, char *buf)
  96 {
  97         struct ir_input_dev *ir_dev = dev_get_drvdata(d);
  98         struct decoder_data *data = get_decoder_data(ir_dev);
  99
 100         if (!data)
 101                 return -EINVAL;
 102
 103         if (data->enabled)
 104                 return sprintf(buf, "1\n");
 105         else
 106         return sprintf(buf, "0\n");
 107 }
 108
 109 static DEVICE_ATTR(enabled, S_IRUGO | S_IWUSR, show_enabled, store_enabled);
 110
 111 static struct attribute *decoder_attributes[] = {
 112         &dev_attr_enabled.attr,
 113         NULL
 114 };
 115
 116 static struct attribute_group decoder_attribute_group = {
 117         .name   = "nec_decoder",
 118         .attrs  = decoder_attributes,
 119 };
 120
 121 /**
 122  * ir_nec_decode() - Decode one NEC pulse or space
 123  * @input_dev:  the struct input_dev descriptor of the device
 124  * @duration:   the struct ir_raw_event descriptor of the pulse/space
 125  *
 126  * This function returns -EINVAL if the pulse violates the state machine
 127  */
 128 static int ir_nec_decode(struct input_dev *input_dev, struct ir_raw_event ev)
 129 {
 130         struct decoder_data *data;
 131         struct ir_input_dev *ir_dev = input_get_drvdata(input_dev);
 132         u32 scancode;
 133         u8 address, not_address, command, not_command;
 134
 135         data = get_decoder_data(ir_dev);
 136         if (!data)
 137                 return -EINVAL;
 138
 139         if (!data->enabled)
 140                 return 0;
 141
 142         if (IS_RESET(ev)) {
 143                 data->state = STATE_INACTIVE;
 144                 return 0;
 145         }
 146
 147         IR_dprintk(2, "NEC decode started at state %d (%uus %s)\n",
 148                    data->state, TO_US(ev.duration), TO_STR(ev.pulse));
 149
 150         switch (data->state) {
 151
 152         case STATE_INACTIVE:
 153                 if (!ev.pulse)
 154                         break;
 155
 156                 if (!eq_margin(ev.duration, NEC_HEADER_PULSE, NEC_UNIT / 2) &&
 157                     !eq_margin(ev.duration, NECX_HEADER_PULSE, NEC_UNIT / 2))
 158                         break;
 159
 160                 data->count = 0;
 161                 data->state = STATE_HEADER_SPACE;
 162                 return 0;
 163
 164         case STATE_HEADER_SPACE:
 165                 if (ev.pulse)
 166                         break;
 167
 168                 if (eq_margin(ev.duration, NEC_HEADER_SPACE, NEC_UNIT / 2)) {
 169                         data->state = STATE_BIT_PULSE;
 170                         return 0;
 171                 } else if (eq_margin(ev.duration, NEC_REPEAT_SPACE, NEC_UNIT / 2)) {
 172                         ir_repeat(input_dev);
 173                         IR_dprintk(1, "Repeat last key\n");
 174                         data->state = STATE_TRAILER_PULSE;
 175                         return 0;
 176                 }
 177
 178                 break;
 179
 180         case STATE_BIT_PULSE:
 181                 if (!ev.pulse)
 182                         break;
 183
 184                 if (!eq_margin(ev.duration, NEC_BIT_PULSE, NEC_UNIT / 2))
 185                         break;
 186
 187                 data->state = STATE_BIT_SPACE;
 188                 return 0;
 189
 190         case STATE_BIT_SPACE:
 191                 if (ev.pulse)
 192                         break;
 193
 194                 data->nec_bits <<= 1;
 195                 if (eq_margin(ev.duration, NEC_BIT_1_SPACE, NEC_UNIT / 2))
 196                         data->nec_bits |= 1;
 197                 else if (!eq_margin(ev.duration, NEC_BIT_0_SPACE, NEC_UNIT / 2))
 198                         break;
 199                 data->count++;
 200
 201                 if (data->count == NEC_NBITS)
 202                         data->state = STATE_TRAILER_PULSE;
 203                 else
 204                         data->state = STATE_BIT_PULSE;
 205
 206                 return 0;
 207
 208         case STATE_TRAILER_PULSE:
 209                 if (!ev.pulse)
 210                         break;
 211
 212                 if (!eq_margin(ev.duration, NEC_TRAILER_PULSE, NEC_UNIT / 2))
 213                         break;
 214
 215                 data->state = STATE_TRAILER_SPACE;
 216                 return 0;
 217
 218         case STATE_TRAILER_SPACE:
 219                 if (ev.pulse)
 220                         break;
 221
 222                 if (!geq_margin(ev.duration, NEC_TRAILER_SPACE, NEC_UNIT / 2))
 223                         break;
 224
 225                 address     = bitrev8((data->nec_bits >> 24) & 0xff);
 226                 not_address = bitrev8((data->nec_bits >> 16) & 0xff);
 227                 command     = bitrev8((data->nec_bits >>  8) & 0xff);
 228                 not_command = bitrev8((data->nec_bits >>  0) & 0xff);
 229
 230                 if ((command ^ not_command) != 0xff) {
 231                         IR_dprintk(1, "NEC checksum error: received 0x%08x\n",
 232                                    data->nec_bits);
 233                         break;
 234                 }
 235
 236                 if ((address ^ not_address) != 0xff) {
 237                         /* Extended NEC */
 238                         scancode = address     << 16 |
 239                                    not_address <<  8 |
 240                                    command;
 241                         IR_dprintk(1, "NEC (Ext) scancode 0x%06x\n", scancode);
 242                 } else {
 243                         /* Normal NEC */
 244                         scancode = address << 8 | command;
 245                         IR_dprintk(1, "NEC scancode 0x%04x\n", scancode);
 246                 }
 247
 248                 ir_keydown(input_dev, scancode, 0);
 249                 data->state = STATE_INACTIVE;
 250                 return 0;
 251         }
 252
 253         IR_dprintk(1, "NEC decode failed at state %d (%uus %s)\n",
 254                    data->state, TO_US(ev.duration), TO_STR(ev.pulse));
 255         data->state = STATE_INACTIVE;
 256         return -EINVAL;
 257 }
 258
 259 static int ir_nec_register(struct input_dev *input_dev)
 260 {
 261         struct ir_input_dev *ir_dev = input_get_drvdata(input_dev);
 262         struct decoder_data *data;
 263         int rc;
 264
 265         rc = sysfs_create_group(&ir_dev->dev.kobj, &decoder_attribute_group);
 266         if (rc < 0)
 267                 return rc;
 268
 269         data = kzalloc(sizeof(*data), GFP_KERNEL);
 270         if (!data) {
 271                 sysfs_remove_group(&ir_dev->dev.kobj, &decoder_attribute_group);
 272                 return -ENOMEM;
 273         }
 274
 275         data->ir_dev = ir_dev;
 276         data->enabled = 1;
 277
 278         spin_lock(&decoder_lock);
 279         list_add_tail(&data->list, &decoder_list);
 280         spin_unlock(&decoder_lock);
 281
 282         return 0;
 283 }
 284
 285 static int ir_nec_unregister(struct input_dev *input_dev)
 286 {
 287         struct ir_input_dev *ir_dev = input_get_drvdata(input_dev);
 288         static struct decoder_data *data;
 289
 290         data = get_decoder_data(ir_dev);
 291         if (!data)
 292                 return 0;
 293
 294         sysfs_remove_group(&ir_dev->dev.kobj, &decoder_attribute_group);
 295
 296         spin_lock(&decoder_lock);
 297         list_del(&data->list);
 298         spin_unlock(&decoder_lock);
 299
 300         return 0;
 301 }
 302
 303 static struct ir_raw_handler nec_handler = {
 304         .decode         = ir_nec_decode,
 305         .raw_register   = ir_nec_register,
 306         .raw_unregister = ir_nec_unregister,
 307 };
 308
 309 static int __init ir_nec_decode_init(void)
 310 {
 311         ir_raw_handler_register(&nec_handler);
 312
 313         printk(KERN_INFO "IR NEC protocol handler initialized\n");
 314         return 0;
 315 }
 316
 317 static void __exit ir_nec_decode_exit(void)
 318 {
 319         ir_raw_handler_unregister(&nec_handler);
 320 }
 321
 322 module_init(ir_nec_decode_init);
 323 module_exit(ir_nec_decode_exit);
 324
 325 MODULE_LICENSE("GPL");
 326 MODULE_AUTHOR("Mauro Carvalho Chehab <mchehab@redhat.com>");
 327 MODULE_AUTHOR("Red Hat Inc. (http://www.redhat.com)");
 328 MODULE_DESCRIPTION("NEC IR protocol decoder");