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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 #include <linux/bitrev.h>
  17
  18 #define NEC_NBITS               32
  19 #define NEC_UNIT                562500  /* ns */
  20 #define NEC_HEADER_PULSE        PULSE(16)
  21 #define NEC_HEADER_SPACE        SPACE(8)
  22 #define NEC_REPEAT_SPACE        SPACE(4)
  23 #define NEC_BIT_PULSE           PULSE(1)
  24 #define NEC_BIT_0_SPACE         SPACE(1)
  25 #define NEC_BIT_1_SPACE         SPACE(3)
  26
  27 /* Used to register nec_decoder clients */
  28 static LIST_HEAD(decoder_list);
  29 static DEFINE_SPINLOCK(decoder_lock);
  30
  31 enum nec_state {
  32         STATE_INACTIVE,
  33         STATE_HEADER_SPACE,
  34         STATE_BIT_PULSE,
  35         STATE_BIT_SPACE,
  36         STATE_TRAILER_PULSE,
  37         STATE_TRAILER_SPACE,
  38 };
  39
  40 struct decoder_data {
  41         struct list_head        list;
  42         struct ir_input_dev     *ir_dev;
  43         int                     enabled:1;
  44
  45         /* State machine control */
  46         enum nec_state          state;
  47         u32                     nec_bits;
  48         unsigned                count;
  49 };
  50
  51
  52 /**
  53  * get_decoder_data()   - gets decoder data
  54  * @input_dev:  input device
  55  *
  56  * Returns the struct decoder_data that corresponds to a device
  57  */
  58 static struct decoder_data *get_decoder_data(struct  ir_input_dev *ir_dev)
  59 {
  60         struct decoder_data *data = NULL;
  61
  62         spin_lock(&decoder_lock);
  63         list_for_each_entry(data, &decoder_list, list) {
  64                 if (data->ir_dev == ir_dev)
  65                         break;
  66         }
  67         spin_unlock(&decoder_lock);
  68         return data;
  69 }
  70
  71 static ssize_t store_enabled(struct device *d,
  72                              struct device_attribute *mattr,
  73                              const char *buf,
  74                              size_t len)
  75 {
  76         unsigned long value;
  77         struct ir_input_dev *ir_dev = dev_get_drvdata(d);
  78         struct decoder_data *data = get_decoder_data(ir_dev);
  79
  80         if (!data)
  81                 return -EINVAL;
  82
  83         if (strict_strtoul(buf, 10, &value) || value > 1)
  84                 return -EINVAL;
  85
  86         data->enabled = value;
  87
  88         return len;
  89 }
  90
  91 static ssize_t show_enabled(struct device *d,
  92                              struct device_attribute *mattr, char *buf)
  93 {
  94         struct ir_input_dev *ir_dev = dev_get_drvdata(d);
  95         struct decoder_data *data = get_decoder_data(ir_dev);
  96
  97         if (!data)
  98                 return -EINVAL;
  99
 100         if (data->enabled)
 101                 return sprintf(buf, "1\n");
 102         else
 103         return sprintf(buf, "0\n");
 104 }
 105
 106 static DEVICE_ATTR(enabled, S_IRUGO | S_IWUSR, show_enabled, store_enabled);
 107
 108 static struct attribute *decoder_attributes[] = {
 109         &dev_attr_enabled.attr,
 110         NULL
 111 };
 112
 113 static struct attribute_group decoder_attribute_group = {
 114         .name   = "nec_decoder",
 115         .attrs  = decoder_attributes,
 116 };
 117
 118 /**
 119  * ir_nec_decode() - Decode one NEC pulse or space
 120  * @input_dev:  the struct input_dev descriptor of the device
 121  * @duration:   duration in ns of pulse/space
 122  *
 123  * This function returns -EINVAL if the pulse violates the state machine
 124  */
 125 static int ir_nec_decode(struct input_dev *input_dev, s64 duration)
 126 {
 127         struct decoder_data *data;
 128         struct ir_input_dev *ir_dev = input_get_drvdata(input_dev);
 129         int u;
 130         u32 scancode;
 131         u8 address, not_address, command, not_command;
 132
 133         data = get_decoder_data(ir_dev);
 134         if (!data)
 135                 return -EINVAL;
 136
 137         if (!data->enabled)
 138                 return 0;
 139
 140         if (IS_RESET(duration)) {
 141                 data->state = STATE_INACTIVE;
 142                 return 0;
 143         }
 144
 145         u = TO_UNITS(duration, NEC_UNIT);
 146         if (DURATION(u) == 0)
 147                 goto out;
 148
 149         IR_dprintk(2, "NEC decode started at state %d (%i units, %ius)\n",
 150                    data->state, u, TO_US(duration));
 151
 152         switch (data->state) {
 153
 154         case STATE_INACTIVE:
 155                 if (u == NEC_HEADER_PULSE) {
 156                         data->count = 0;
 157                         data->state = STATE_HEADER_SPACE;
 158                 }
 159                 return 0;
 160
 161         case STATE_HEADER_SPACE:
 162                 if (u == NEC_HEADER_SPACE) {
 163                         data->state = STATE_BIT_PULSE;
 164                         return 0;
 165                 } else if (u == NEC_REPEAT_SPACE) {
 166                         ir_repeat(input_dev);
 167                         IR_dprintk(1, "Repeat last key\n");
 168                         data->state = STATE_TRAILER_PULSE;
 169                         return 0;
 170                 }
 171                 break;
 172
 173         case STATE_BIT_PULSE:
 174                 if (u == NEC_BIT_PULSE) {
 175                         data->state = STATE_BIT_SPACE;
 176                         return 0;
 177                 }
 178                 break;
 179
 180         case STATE_BIT_SPACE:
 181                 if (u != NEC_BIT_0_SPACE && u != NEC_BIT_1_SPACE)
 182                         break;
 183
 184                 data->nec_bits <<= 1;
 185                 if (u == NEC_BIT_1_SPACE)
 186                         data->nec_bits |= 1;
 187                 data->count++;
 188
 189                 if (data->count != NEC_NBITS) {
 190                         data->state = STATE_BIT_PULSE;
 191                         return 0;
 192                 }
 193
 194                 address     = bitrev8((data->nec_bits >> 24) & 0xff);
 195                 not_address = bitrev8((data->nec_bits >> 16) & 0xff);
 196                 command     = bitrev8((data->nec_bits >>  8) & 0xff);
 197                 not_command = bitrev8((data->nec_bits >>  0) & 0xff);
 198
 199                 if ((command ^ not_command) != 0xff) {
 200                         IR_dprintk(1, "NEC checksum error: received 0x%08x\n",
 201                                    data->nec_bits);
 202                         break;
 203                 }
 204
 205                 if ((address ^ not_address) != 0xff) {
 206                         /* Extended NEC */
 207                         scancode = address     << 16 |
 208                                    not_address <<  8 |
 209                                    command;
 210                         IR_dprintk(1, "NEC (Ext) scancode 0x%06x\n", scancode);
 211                 } else {
 212                         /* normal NEC */
 213                         scancode = address << 8 | command;
 214                         IR_dprintk(1, "NEC scancode 0x%04x\n", scancode);
 215                 }
 216
 217                 ir_keydown(input_dev, scancode, 0);
 218                 data->state = STATE_TRAILER_PULSE;
 219                 return 0;
 220
 221         case STATE_TRAILER_PULSE:
 222                 if (u > 0) {
 223                         data->state = STATE_TRAILER_SPACE;
 224                         return 0;
 225                 }
 226                 break;
 227
 228         case STATE_TRAILER_SPACE:
 229                 if (u < 0) {
 230                         data->state = STATE_INACTIVE;
 231                         return 0;
 232                 }
 233
 234                 break;
 235         }
 236
 237 out:
 238         IR_dprintk(1, "NEC decode failed at state %d (%i units, %ius)\n",
 239                    data->state, u, TO_US(duration));
 240         data->state = STATE_INACTIVE;
 241         return -EINVAL;
 242 }
 243
 244 static int ir_nec_register(struct input_dev *input_dev)
 245 {
 246         struct ir_input_dev *ir_dev = input_get_drvdata(input_dev);
 247         struct decoder_data *data;
 248         int rc;
 249
 250         rc = sysfs_create_group(&ir_dev->dev.kobj, &decoder_attribute_group);
 251         if (rc < 0)
 252                 return rc;
 253
 254         data = kzalloc(sizeof(*data), GFP_KERNEL);
 255         if (!data) {
 256                 sysfs_remove_group(&ir_dev->dev.kobj, &decoder_attribute_group);
 257                 return -ENOMEM;
 258         }
 259
 260         data->ir_dev = ir_dev;
 261         data->enabled = 1;
 262
 263         spin_lock(&decoder_lock);
 264         list_add_tail(&data->list, &decoder_list);
 265         spin_unlock(&decoder_lock);
 266
 267         return 0;
 268 }
 269
 270 static int ir_nec_unregister(struct input_dev *input_dev)
 271 {
 272         struct ir_input_dev *ir_dev = input_get_drvdata(input_dev);
 273         static struct decoder_data *data;
 274
 275         data = get_decoder_data(ir_dev);
 276         if (!data)
 277                 return 0;
 278
 279         sysfs_remove_group(&ir_dev->dev.kobj, &decoder_attribute_group);
 280
 281         spin_lock(&decoder_lock);
 282         list_del(&data->list);
 283         spin_unlock(&decoder_lock);
 284
 285         return 0;
 286 }
 287
 288 static struct ir_raw_handler nec_handler = {
 289         .decode         = ir_nec_decode,
 290         .raw_register   = ir_nec_register,
 291         .raw_unregister = ir_nec_unregister,
 292 };
 293
 294 static int __init ir_nec_decode_init(void)
 295 {
 296         ir_raw_handler_register(&nec_handler);
 297
 298         printk(KERN_INFO "IR NEC protocol handler initialized\n");
 299         return 0;
 300 }
 301
 302 static void __exit ir_nec_decode_exit(void)
 303 {
 304         ir_raw_handler_unregister(&nec_handler);
 305 }
 306
 307 module_init(ir_nec_decode_init);
 308 module_exit(ir_nec_decode_exit);
 309
 310 MODULE_LICENSE("GPL");
 311 MODULE_AUTHOR("Mauro Carvalho Chehab <mchehab@redhat.com>");
 312 MODULE_AUTHOR("Red Hat Inc. (http://www.redhat.com)");
 313 MODULE_DESCRIPTION("NEC IR protocol decoder");