drivers/w1/w1_io.c

   1 /*
   2  * Copyright (c) 2004 Evgeniy Polyakov <zbr@ioremap.net>
   3  *
   4  * This program is free software; you can redistribute it and/or modify
   5  * it under the terms of the GNU General Public License as published by
   6  * the Free Software Foundation; either version 2 of the License, or
   7  * (at your option) any later version.
   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 <asm/io.h>
  16
  17 #include <linux/delay.h>
  18 #include <linux/moduleparam.h>
  19 #include <linux/module.h>
  20
  21 #include "w1_internal.h"
  22
  23 static int w1_delay_parm = 1;
  24 module_param_named(delay_coef, w1_delay_parm, int, 0);
  25
  26 static int w1_disable_irqs = 0;
  27 module_param_named(disable_irqs, w1_disable_irqs, int, 0);
  28
  29 static u8 w1_crc8_table[] = {
  30         0, 94, 188, 226, 97, 63, 221, 131, 194, 156, 126, 32, 163, 253, 31, 65,
  31         157, 195, 33, 127, 252, 162, 64, 30, 95, 1, 227, 189, 62, 96, 130, 220,
  32         35, 125, 159, 193, 66, 28, 254, 160, 225, 191, 93, 3, 128, 222, 60, 98,
  33         190, 224, 2, 92, 223, 129, 99, 61, 124, 34, 192, 158, 29, 67, 161, 255,
  34         70, 24, 250, 164, 39, 121, 155, 197, 132, 218, 56, 102, 229, 187, 89, 7,
  35         219, 133, 103, 57, 186, 228, 6, 88, 25, 71, 165, 251, 120, 38, 196, 154,
  36         101, 59, 217, 135, 4, 90, 184, 230, 167, 249, 27, 69, 198, 152, 122, 36,
  37         248, 166, 68, 26, 153, 199, 37, 123, 58, 100, 134, 216, 91, 5, 231, 185,
  38         140, 210, 48, 110, 237, 179, 81, 15, 78, 16, 242, 172, 47, 113, 147, 205,
  39         17, 79, 173, 243, 112, 46, 204, 146, 211, 141, 111, 49, 178, 236, 14, 80,
  40         175, 241, 19, 77, 206, 144, 114, 44, 109, 51, 209, 143, 12, 82, 176, 238,
  41         50, 108, 142, 208, 83, 13, 239, 177, 240, 174, 76, 18, 145, 207, 45, 115,
  42         202, 148, 118, 40, 171, 245, 23, 73, 8, 86, 180, 234, 105, 55, 213, 139,
  43         87, 9, 235, 181, 54, 104, 138, 212, 149, 203, 41, 119, 244, 170, 72, 22,
  44         233, 183, 85, 11, 136, 214, 52, 106, 43, 117, 151, 201, 74, 20, 246, 168,
  45         116, 42, 200, 150, 21, 75, 169, 247, 182, 232, 10, 84, 215, 137, 107, 53
  46 };
  47
  48 static void w1_delay(unsigned long tm)
  49 {
  50         udelay(tm * w1_delay_parm);
  51 }
  52
  53 static void w1_write_bit(struct w1_master *dev, int bit);
  54 static u8 w1_read_bit(struct w1_master *dev);
  55
  56 /**
  57  * w1_touch_bit() - Generates a write-0 or write-1 cycle and samples the level.
  58  * @dev:        the master device
  59  * @bit:        0 - write a 0, 1 - write a 0 read the level
  60  */
  61 u8 w1_touch_bit(struct w1_master *dev, int bit)
  62 {
  63         if (dev->bus_master->touch_bit)
  64                 return dev->bus_master->touch_bit(dev->bus_master->data, bit);
  65         else if (bit)
  66                 return w1_read_bit(dev);
  67         else {
  68                 w1_write_bit(dev, 0);
  69                 return 0;
  70         }
  71 }
  72 EXPORT_SYMBOL_GPL(w1_touch_bit);
  73
  74 /**
  75  * w1_write_bit() - Generates a write-0 or write-1 cycle.
  76  * @dev:        the master device
  77  * @bit:        bit to write
  78  *
  79  * Only call if dev->bus_master->touch_bit is NULL
  80  */
  81 static void w1_write_bit(struct w1_master *dev, int bit)
  82 {
  83         unsigned long flags = 0;
  84
  85         if(w1_disable_irqs) local_irq_save(flags);
  86
  87         if (bit) {
  88                 dev->bus_master->write_bit(dev->bus_master->data, 0);
  89                 w1_delay(6);
  90                 dev->bus_master->write_bit(dev->bus_master->data, 1);
  91                 w1_delay(64);
  92         } else {
  93                 dev->bus_master->write_bit(dev->bus_master->data, 0);
  94                 w1_delay(60);
  95                 dev->bus_master->write_bit(dev->bus_master->data, 1);
  96                 w1_delay(10);
  97         }
  98
  99         if(w1_disable_irqs) local_irq_restore(flags);
 100 }
 101
 102 /**
 103  * w1_pre_write() - pre-write operations
 104  * @dev:        the master device
 105  *
 106  * Pre-write operation, currently only supporting strong pullups.
 107  * Program the hardware for a strong pullup, if one has been requested and
 108  * the hardware supports it.
 109  */
 110 static void w1_pre_write(struct w1_master *dev)
 111 {
 112         if (dev->pullup_duration &&
 113                 dev->enable_pullup && dev->bus_master->set_pullup) {
 114                 dev->bus_master->set_pullup(dev->bus_master->data,
 115                         dev->pullup_duration);
 116         }
 117 }
 118
 119 /**
 120  * w1_post_write() - post-write options
 121  * @dev:        the master device
 122  *
 123  * Post-write operation, currently only supporting strong pullups.
 124  * If a strong pullup was requested, clear it if the hardware supports
 125  * them, or execute the delay otherwise, in either case clear the request.
 126  */
 127 static void w1_post_write(struct w1_master *dev)
 128 {
 129         if (dev->pullup_duration) {
 130                 if (dev->enable_pullup && dev->bus_master->set_pullup)
 131                         dev->bus_master->set_pullup(dev->bus_master->data, 0);
 132                 else
 133                         msleep(dev->pullup_duration);
 134                 dev->pullup_duration = 0;
 135         }
 136 }
 137
 138 /**
 139  * w1_write_8() - Writes 8 bits.
 140  * @dev:        the master device
 141  * @byte:       the byte to write
 142  */
 143 void w1_write_8(struct w1_master *dev, u8 byte)
 144 {
 145         int i;
 146
 147         if (dev->bus_master->write_byte) {
 148                 w1_pre_write(dev);
 149                 dev->bus_master->write_byte(dev->bus_master->data, byte);
 150         }
 151         else
 152                 for (i = 0; i < 8; ++i) {
 153                         if (i == 7)
 154                                 w1_pre_write(dev);
 155                         w1_touch_bit(dev, (byte >> i) & 0x1);
 156                 }
 157         w1_post_write(dev);
 158 }
 159 EXPORT_SYMBOL_GPL(w1_write_8);
 160
 161
 162 /**
 163  * w1_read_bit() - Generates a write-1 cycle and samples the level.
 164  * @dev:        the master device
 165  *
 166  * Only call if dev->bus_master->touch_bit is NULL
 167  */
 168 static u8 w1_read_bit(struct w1_master *dev)
 169 {
 170         int result;
 171         unsigned long flags = 0;
 172
 173         /* sample timing is critical here */
 174         local_irq_save(flags);
 175         dev->bus_master->write_bit(dev->bus_master->data, 0);
 176         w1_delay(6);
 177         dev->bus_master->write_bit(dev->bus_master->data, 1);
 178         w1_delay(9);
 179
 180         result = dev->bus_master->read_bit(dev->bus_master->data);
 181         local_irq_restore(flags);
 182
 183         w1_delay(55);
 184
 185         return result & 0x1;
 186 }
 187
 188 /**
 189  * w1_triplet() - * Does a triplet - used for searching ROM addresses.
 190  * @dev:        the master device
 191  * @bdir:       the bit to write if both id_bit and comp_bit are 0
 192  *
 193  * Return bits:
 194  *  bit 0 = id_bit
 195  *  bit 1 = comp_bit
 196  *  bit 2 = dir_taken
 197  * If both bits 0 & 1 are set, the search should be restarted.
 198  *
 199  * Return:        bit fields - see above
 200  */
 201 u8 w1_triplet(struct w1_master *dev, int bdir)
 202 {
 203         if (dev->bus_master->triplet)
 204                 return dev->bus_master->triplet(dev->bus_master->data, bdir);
 205         else {
 206                 u8 id_bit   = w1_touch_bit(dev, 1);
 207                 u8 comp_bit = w1_touch_bit(dev, 1);
 208                 u8 retval;
 209
 210                 if (id_bit && comp_bit)
 211                         return 0x03;  /* error */
 212
 213                 if (!id_bit && !comp_bit) {
 214                         /* Both bits are valid, take the direction given */
 215                         retval = bdir ? 0x04 : 0;
 216                 } else {
 217                         /* Only one bit is valid, take that direction */
 218                         bdir = id_bit;
 219                         retval = id_bit ? 0x05 : 0x02;
 220                 }
 221
 222                 if (dev->bus_master->touch_bit)
 223                         w1_touch_bit(dev, bdir);
 224                 else
 225                         w1_write_bit(dev, bdir);
 226                 return retval;
 227         }
 228 }
 229 EXPORT_SYMBOL_GPL(w1_triplet);
 230
 231 /**
 232  * w1_read_8() - Reads 8 bits.
 233  * @dev:        the master device
 234  *
 235  * Return:        the byte read
 236  */
 237 u8 w1_read_8(struct w1_master *dev)
 238 {
 239         int i;
 240         u8 res = 0;
 241
 242         if (dev->bus_master->read_byte)
 243                 res = dev->bus_master->read_byte(dev->bus_master->data);
 244         else
 245                 for (i = 0; i < 8; ++i)
 246                         res |= (w1_touch_bit(dev,1) << i);
 247
 248         return res;
 249 }
 250 EXPORT_SYMBOL_GPL(w1_read_8);
 251
 252 /**
 253  * w1_write_block() - Writes a series of bytes.
 254  * @dev:        the master device
 255  * @buf:        pointer to the data to write
 256  * @len:        the number of bytes to write
 257  */
 258 void w1_write_block(struct w1_master *dev, const u8 *buf, int len)
 259 {
 260         int i;
 261
 262         if (dev->bus_master->write_block) {
 263                 w1_pre_write(dev);
 264                 dev->bus_master->write_block(dev->bus_master->data, buf, len);
 265         }
 266         else
 267                 for (i = 0; i < len; ++i)
 268                         w1_write_8(dev, buf[i]); /* calls w1_pre_write */
 269         w1_post_write(dev);
 270 }
 271 EXPORT_SYMBOL_GPL(w1_write_block);
 272
 273 /**
 274  * w1_touch_block() - Touches a series of bytes.
 275  * @dev:        the master device
 276  * @buf:        pointer to the data to write
 277  * @len:        the number of bytes to write
 278  */
 279 void w1_touch_block(struct w1_master *dev, u8 *buf, int len)
 280 {
 281         int i, j;
 282         u8 tmp;
 283
 284         for (i = 0; i < len; ++i) {
 285                 tmp = 0;
 286                 for (j = 0; j < 8; ++j) {
 287                         if (j == 7)
 288                                 w1_pre_write(dev);
 289                         tmp |= w1_touch_bit(dev, (buf[i] >> j) & 0x1) << j;
 290                 }
 291
 292                 buf[i] = tmp;
 293         }
 294 }
 295 EXPORT_SYMBOL_GPL(w1_touch_block);
 296
 297 /**
 298  * w1_read_block() - Reads a series of bytes.
 299  * @dev:        the master device
 300  * @buf:        pointer to the buffer to fill
 301  * @len:        the number of bytes to read
 302  * Return:      the number of bytes read
 303  */
 304 u8 w1_read_block(struct w1_master *dev, u8 *buf, int len)
 305 {
 306         int i;
 307         u8 ret;
 308
 309         if (dev->bus_master->read_block)
 310                 ret = dev->bus_master->read_block(dev->bus_master->data, buf, len);
 311         else {
 312                 for (i = 0; i < len; ++i)
 313                         buf[i] = w1_read_8(dev);
 314                 ret = len;
 315         }
 316
 317         return ret;
 318 }
 319 EXPORT_SYMBOL_GPL(w1_read_block);
 320
 321 /**
 322  * w1_reset_bus() - Issues a reset bus sequence.
 323  * @dev:        the master device
 324  * Return:      0=Device present, 1=No device present or error
 325  */
 326 int w1_reset_bus(struct w1_master *dev)
 327 {
 328         int result;
 329         unsigned long flags = 0;
 330
 331         if(w1_disable_irqs) local_irq_save(flags);
 332
 333         if (dev->bus_master->reset_bus)
 334                 result = dev->bus_master->reset_bus(dev->bus_master->data) & 0x1;
 335         else {
 336                 dev->bus_master->write_bit(dev->bus_master->data, 0);
 337                 /* minimum 480, max ? us
 338                  * be nice and sleep, except 18b20 spec lists 960us maximum,
 339                  * so until we can sleep with microsecond accuracy, spin.
 340                  * Feel free to come up with some other way to give up the
 341                  * cpu for such a short amount of time AND get it back in
 342                  * the maximum amount of time.
 343                  */
 344                 w1_delay(500);
 345                 dev->bus_master->write_bit(dev->bus_master->data, 1);
 346                 w1_delay(70);
 347
 348                 result = dev->bus_master->read_bit(dev->bus_master->data) & 0x1;
 349                 /* minimum 70 (above) + 430 = 500 us
 350                  * There aren't any timing requirements between a reset and
 351                  * the following transactions.  Sleeping is safe here.
 352                  */
 353                 /* w1_delay(430); min required time */
 354                 msleep(1);
 355         }
 356
 357         if(w1_disable_irqs) local_irq_restore(flags);
 358
 359         return result;
 360 }
 361 EXPORT_SYMBOL_GPL(w1_reset_bus);
 362
 363 u8 w1_calc_crc8(u8 * data, int len)
 364 {
 365         u8 crc = 0;
 366
 367         while (len--)
 368                 crc = w1_crc8_table[crc ^ *data++];
 369
 370         return crc;
 371 }
 372 EXPORT_SYMBOL_GPL(w1_calc_crc8);
 373
 374 void w1_search_devices(struct w1_master *dev, u8 search_type, w1_slave_found_callback cb)
 375 {
 376         dev->attempts++;
 377         if (dev->bus_master->search)
 378                 dev->bus_master->search(dev->bus_master->data, dev,
 379                         search_type, cb);
 380         else
 381                 w1_search(dev, search_type, cb);
 382 }
 383
 384 /**
 385  * w1_reset_select_slave() - reset and select a slave
 386  * @sl:         the slave to select
 387  *
 388  * Resets the bus and then selects the slave by sending either a skip rom
 389  * or a rom match.  A skip rom is issued if there is only one device
 390  * registered on the bus.
 391  * The w1 master lock must be held.
 392  *
 393  * Return:      0=success, anything else=error
 394  */
 395 int w1_reset_select_slave(struct w1_slave *sl)
 396 {
 397         if (w1_reset_bus(sl->master))
 398                 return -1;
 399
 400         if (sl->master->slave_count == 1)
 401                 w1_write_8(sl->master, W1_SKIP_ROM);
 402         else {
 403                 u8 match[9] = {W1_MATCH_ROM, };
 404                 u64 rn = le64_to_cpu(*((u64*)&sl->reg_num));
 405
 406                 memcpy(&match[1], &rn, 8);
 407                 w1_write_block(sl->master, match, 9);
 408         }
 409         return 0;
 410 }
 411 EXPORT_SYMBOL_GPL(w1_reset_select_slave);
 412
 413 /**
 414  * w1_reset_resume_command() - resume instead of another match ROM
 415  * @dev:        the master device
 416  *
 417  * When the workflow with a slave amongst many requires several
 418  * successive commands a reset between each, this function is similar
 419  * to doing a reset then a match ROM for the last matched ROM. The
 420  * advantage being that the matched ROM step is skipped in favor of the
 421  * resume command. The slave must support the command of course.
 422  *
 423  * If the bus has only one slave, traditionnaly the match ROM is skipped
 424  * and a "SKIP ROM" is done for efficiency. On multi-slave busses, this
 425  * doesn't work of course, but the resume command is the next best thing.
 426  *
 427  * The w1 master lock must be held.
 428  */
 429 int w1_reset_resume_command(struct w1_master *dev)
 430 {
 431         if (w1_reset_bus(dev))
 432                 return -1;
 433
 434         /* This will make only the last matched slave perform a skip ROM. */
 435         w1_write_8(dev, W1_RESUME_CMD);
 436         return 0;
 437 }
 438 EXPORT_SYMBOL_GPL(w1_reset_resume_command);
 439
 440 /**
 441  * w1_next_pullup() - register for a strong pullup
 442  * @dev:        the master device
 443  * @delay:      time in milliseconds
 444  *
 445  * Put out a strong pull-up of the specified duration after the next write
 446  * operation.  Not all hardware supports strong pullups.  Hardware that
 447  * doesn't support strong pullups will sleep for the given time after the
 448  * write operation without a strong pullup.  This is a one shot request for
 449  * the next write, specifying zero will clear a previous request.
 450  * The w1 master lock must be held.
 451  *
 452  * Return:      0=success, anything else=error
 453  */
 454 void w1_next_pullup(struct w1_master *dev, int delay)
 455 {
 456         dev->pullup_duration = delay;
 457 }
 458 EXPORT_SYMBOL_GPL(w1_next_pullup);