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