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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 <media/ir-core.h>
  16
  17 #define NEC_NBITS               32
  18 #define NEC_UNIT                559979 /* ns */
  19 #define NEC_HEADER_MARK         (16 * NEC_UNIT)
  20 #define NEC_HEADER_SPACE        (8 * NEC_UNIT)
  21 #define NEC_REPEAT_SPACE        (4 * NEC_UNIT)
  22 #define NEC_MARK                (NEC_UNIT)
  23 #define NEC_0_SPACE             (NEC_UNIT)
  24 #define NEC_1_SPACE             (3 * NEC_UNIT)
  25
  26 /* Used to register nec_decoder clients */
  27 static LIST_HEAD(decoder_list);
  28 static DEFINE_SPINLOCK(decoder_lock);
  29
  30 enum nec_state {
  31         STATE_INACTIVE,
  32         STATE_HEADER_MARK,
  33         STATE_HEADER_SPACE,
  34         STATE_MARK,
  35         STATE_SPACE,
  36         STATE_TRAILER_MARK,
  37         STATE_TRAILER_SPACE,
  38 };
  39
  40 struct nec_code {
  41         u8      address;
  42         u8      not_address;
  43         u8      command;
  44         u8      not_command;
  45 };
  46
  47 struct decoder_data {
  48         struct list_head        list;
  49         struct ir_input_dev     *ir_dev;
  50         int                     enabled:1;
  51
  52         /* State machine control */
  53         enum nec_state          state;
  54         struct nec_code         nec_code;
  55         unsigned                count;
  56 };
  57
  58
  59 /**
  60  * get_decoder_data()   - gets decoder data
  61  * @input_dev:  input device
  62  *
  63  * Returns the struct decoder_data that corresponds to a device
  64  */
  65
  66 static struct decoder_data *get_decoder_data(struct  ir_input_dev *ir_dev)
  67 {
  68         struct decoder_data *data = NULL;
  69
  70         spin_lock(&decoder_lock);
  71         list_for_each_entry(data, &decoder_list, list) {
  72                 if (data->ir_dev == ir_dev)
  73                         break;
  74         }
  75         spin_unlock(&decoder_lock);
  76         return data;
  77 }
  78
  79 static ssize_t store_enabled(struct device *d,
  80                              struct device_attribute *mattr,
  81                              const char *buf,
  82                              size_t len)
  83 {
  84         unsigned long value;
  85         struct ir_input_dev *ir_dev = dev_get_drvdata(d);
  86         struct decoder_data *data = get_decoder_data(ir_dev);
  87
  88         if (!data)
  89                 return -EINVAL;
  90
  91         if (strict_strtoul(buf, 10, &value) || value > 1)
  92                 return -EINVAL;
  93
  94         data->enabled = value;
  95
  96         return len;
  97 }
  98
  99 static ssize_t show_enabled(struct device *d,
 100                              struct device_attribute *mattr, char *buf)
 101 {
 102         struct ir_input_dev *ir_dev = dev_get_drvdata(d);
 103         struct decoder_data *data = get_decoder_data(ir_dev);
 104
 105         if (!data)
 106                 return -EINVAL;
 107
 108         if (data->enabled)
 109                 return sprintf(buf, "1\n");
 110         else
 111         return sprintf(buf, "0\n");
 112 }
 113
 114 static DEVICE_ATTR(enabled, S_IRUGO | S_IWUSR, show_enabled, store_enabled);
 115
 116 static struct attribute *decoder_attributes[] = {
 117         &dev_attr_enabled.attr,
 118         NULL
 119 };
 120
 121 static struct attribute_group decoder_attribute_group = {
 122         .name   = "nec_decoder",
 123         .attrs  = decoder_attributes,
 124 };
 125
 126
 127 /**
 128  * ir_nec_decode() - Decode one NEC pulse or space
 129  * @input_dev:  the struct input_dev descriptor of the device
 130  * @ev:         event array with type/duration of pulse/space
 131  *
 132  * This function returns -EINVAL if the pulse violates the state machine
 133  */
 134 static int ir_nec_decode(struct input_dev *input_dev,
 135                          struct ir_raw_event *ev)
 136 {
 137         struct decoder_data *data;
 138         struct ir_input_dev *ir_dev = input_get_drvdata(input_dev);
 139         int bit, last_bit;
 140
 141         data = get_decoder_data(ir_dev);
 142         if (!data)
 143                 return -EINVAL;
 144
 145         if (!data->enabled)
 146                 return 0;
 147
 148         /* Except for the initial event, what matters is the previous bit */
 149         bit = (ev->type & IR_PULSE) ? 1 : 0;
 150
 151         last_bit = !bit;
 152
 153         /* Discards spurious space last_bits when inactive */
 154
 155         /* Very long delays are considered as start events */
 156         if (ev->delta.tv_nsec > NEC_HEADER_MARK + NEC_HEADER_SPACE - NEC_UNIT / 2)
 157                 data->state = STATE_INACTIVE;
 158
 159         if (ev->type & IR_START_EVENT)
 160                 data->state = STATE_INACTIVE;
 161
 162         switch (data->state) {
 163         case STATE_INACTIVE:
 164                 if (!bit)               /* PULSE marks the start event */
 165                         return 0;
 166
 167                 data->count = 0;
 168                 data->state = STATE_HEADER_MARK;
 169                 memset (&data->nec_code, 0, sizeof(data->nec_code));
 170                 return 0;
 171         case STATE_HEADER_MARK:
 172                 if (!last_bit)
 173                         goto err;
 174                 if (ev->delta.tv_nsec < NEC_HEADER_MARK - 6 * NEC_UNIT)
 175                         goto err;
 176                 data->state = STATE_HEADER_SPACE;
 177                 return 0;
 178         case STATE_HEADER_SPACE:
 179                 if (last_bit)
 180                         goto err;
 181                 if (ev->delta.tv_nsec >= NEC_HEADER_SPACE - NEC_UNIT / 2) {
 182                         data->state = STATE_MARK;
 183                         return 0;
 184                 }
 185
 186                 if (ev->delta.tv_nsec >= NEC_REPEAT_SPACE - NEC_UNIT / 2) {
 187                         ir_repeat(input_dev);
 188                         IR_dprintk(1, "Repeat last key\n");
 189                         data->state = STATE_TRAILER_MARK;
 190                         return 0;
 191                 }
 192                 goto err;
 193         case STATE_MARK:
 194                 if (!last_bit)
 195                         goto err;
 196                 if ((ev->delta.tv_nsec > NEC_MARK + NEC_UNIT / 2) ||
 197                     (ev->delta.tv_nsec < NEC_MARK - NEC_UNIT / 2))
 198                         goto err;
 199                 data->state = STATE_SPACE;
 200                 return 0;
 201         case STATE_SPACE:
 202                 if (last_bit)
 203                         goto err;
 204
 205                 if ((ev->delta.tv_nsec >= NEC_0_SPACE - NEC_UNIT / 2) &&
 206                     (ev->delta.tv_nsec < NEC_0_SPACE + NEC_UNIT / 2))
 207                         bit = 0;
 208                 else if ((ev->delta.tv_nsec >= NEC_1_SPACE - NEC_UNIT / 2) &&
 209                          (ev->delta.tv_nsec < NEC_1_SPACE + NEC_UNIT / 2))
 210                         bit = 1;
 211                 else {
 212                         IR_dprintk(1, "Decode failed at %d-th bit (%s) @%luus\n",
 213                                 data->count,
 214                                 last_bit ? "pulse" : "space",
 215                                 (ev->delta.tv_nsec + 500) / 1000);
 216
 217                         goto err2;
 218                 }
 219
 220                 /* Ok, we've got a valid bit. proccess it */
 221                 if (bit) {
 222                         int shift = data->count;
 223
 224                         /*
 225                          * NEC transmit bytes on this temporal order:
 226                          * address | not address | command | not command
 227                          */
 228                         if (shift < 8) {
 229                                 data->nec_code.address |= 1 << shift;
 230                         } else if (shift < 16) {
 231                                 data->nec_code.not_address |= 1 << (shift - 8);
 232                         } else if (shift < 24) {
 233                                 data->nec_code.command |= 1 << (shift - 16);
 234                         } else {
 235                                 data->nec_code.not_command |= 1 << (shift - 24);
 236                         }
 237                 }
 238                 if (++data->count == NEC_NBITS) {
 239                         u32 scancode;
 240                         /*
 241                          * Fixme: may need to accept Extended NEC protocol?
 242                          */
 243                         if ((data->nec_code.command ^ data->nec_code.not_command) != 0xff)
 244                                 goto checksum_err;
 245
 246                         if ((data->nec_code.address ^ data->nec_code.not_address) != 0xff) {
 247                                 /* Extended NEC */
 248                                 scancode = data->nec_code.address << 16 |
 249                                            data->nec_code.not_address << 8 |
 250                                            data->nec_code.command;
 251                                 IR_dprintk(1, "NEC scancode 0x%06x\n", scancode);
 252                         } else {
 253                                 /* normal NEC */
 254                                 scancode = data->nec_code.address << 8 |
 255                                            data->nec_code.command;
 256                                 IR_dprintk(1, "NEC scancode 0x%04x\n", scancode);
 257                         }
 258                         ir_keydown(input_dev, scancode, 0);
 259
 260                         data->state = STATE_TRAILER_MARK;
 261                 } else
 262                         data->state = STATE_MARK;
 263                 return 0;
 264         case STATE_TRAILER_MARK:
 265                 if (!last_bit)
 266                         goto err;
 267                 data->state = STATE_TRAILER_SPACE;
 268                 return 0;
 269         case STATE_TRAILER_SPACE:
 270                 if (last_bit)
 271                         goto err;
 272                 data->state = STATE_INACTIVE;
 273                 return 0;
 274         }
 275
 276 err:
 277         IR_dprintk(1, "NEC decoded failed at state %d (%s) @ %luus\n",
 278                    data->state,
 279                    bit ? "pulse" : "space",
 280                    (ev->delta.tv_nsec + 500) / 1000);
 281 err2:
 282         data->state = STATE_INACTIVE;
 283         return -EINVAL;
 284
 285 checksum_err:
 286         data->state = STATE_INACTIVE;
 287         IR_dprintk(1, "NEC checksum error: received 0x%02x%02x%02x%02x\n",
 288                    data->nec_code.address,
 289                    data->nec_code.not_address,
 290                    data->nec_code.command,
 291                    data->nec_code.not_command);
 292         return -EINVAL;
 293 }
 294
 295 static int ir_nec_register(struct input_dev *input_dev)
 296 {
 297         struct ir_input_dev *ir_dev = input_get_drvdata(input_dev);
 298         struct decoder_data *data;
 299         int rc;
 300
 301         rc = sysfs_create_group(&ir_dev->dev.kobj, &decoder_attribute_group);
 302         if (rc < 0)
 303                 return rc;
 304
 305         data = kzalloc(sizeof(*data), GFP_KERNEL);
 306         if (!data) {
 307                 sysfs_remove_group(&ir_dev->dev.kobj, &decoder_attribute_group);
 308                 return -ENOMEM;
 309         }
 310
 311         data->ir_dev = ir_dev;
 312         data->enabled = 1;
 313
 314         spin_lock(&decoder_lock);
 315         list_add_tail(&data->list, &decoder_list);
 316         spin_unlock(&decoder_lock);
 317
 318         return 0;
 319 }
 320
 321 static int ir_nec_unregister(struct input_dev *input_dev)
 322 {
 323         struct ir_input_dev *ir_dev = input_get_drvdata(input_dev);
 324         static struct decoder_data *data;
 325
 326         data = get_decoder_data(ir_dev);
 327         if (!data)
 328                 return 0;
 329
 330         sysfs_remove_group(&ir_dev->dev.kobj, &decoder_attribute_group);
 331
 332         spin_lock(&decoder_lock);
 333         list_del(&data->list);
 334         spin_unlock(&decoder_lock);
 335
 336         return 0;
 337 }
 338
 339 static struct ir_raw_handler nec_handler = {
 340         .decode         = ir_nec_decode,
 341         .raw_register   = ir_nec_register,
 342         .raw_unregister = ir_nec_unregister,
 343 };
 344
 345 static int __init ir_nec_decode_init(void)
 346 {
 347         ir_raw_handler_register(&nec_handler);
 348
 349         printk(KERN_INFO "IR NEC protocol handler initialized\n");
 350         return 0;
 351 }
 352
 353 static void __exit ir_nec_decode_exit(void)
 354 {
 355         ir_raw_handler_unregister(&nec_handler);
 356 }
 357
 358 module_init(ir_nec_decode_init);
 359 module_exit(ir_nec_decode_exit);
 360
 361 MODULE_LICENSE("GPL");
 362 MODULE_AUTHOR("Mauro Carvalho Chehab <mchehab@redhat.com>");
 363 MODULE_AUTHOR("Red Hat Inc. (http://www.redhat.com)");
 364 MODULE_DESCRIPTION("NEC IR protocol decoder");