drivers/w1/w1_io.c

   1 /*
   2  *      w1_io.c
   3  *
   4  * Copyright (c) 2004 Evgeniy Polyakov <zbr@ioremap.net>
   5  *
   6  *
   7  * This program is free software; you can redistribute it and/or modify
   8  * it under the terms of the GNU General Public License as published by
   9  * the Free Software Foundation; either version 2 of the License, or
  10  * (at your option) any later version.
  11  *
  12  * This program is distributed in the hope that it will be useful,
  13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15  * GNU General Public License for more details.
  16  *
  17  * You should have received a copy of the GNU General Public License
  18  * along with this program; if not, write to the Free Software
  19  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
  20  */
  21
  22 #include <asm/io.h>
  23
  24 #include <linux/delay.h>
  25 #include <linux/moduleparam.h>
  26 #include <linux/module.h>
  27
  28 #include "w1.h"
  29 #include "w1_log.h"
  30
  31 static int w1_delay_parm = 1;
  32 module_param_named(delay_coef, w1_delay_parm, int, 0);
  33
  34 static int w1_disable_irqs = 0;
  35 module_param_named(disable_irqs, w1_disable_irqs, int, 0);
  36
  37 static u8 w1_crc8_table[] = {
  38         0, 94, 188, 226, 97, 63, 221, 131, 194, 156, 126, 32, 163, 253, 31, 65,
  39         157, 195, 33, 127, 252, 162, 64, 30, 95, 1, 227, 189, 62, 96, 130, 220,
  40         35, 125, 159, 193, 66, 28, 254, 160, 225, 191, 93, 3, 128, 222, 60, 98,
  41         190, 224, 2, 92, 223, 129, 99, 61, 124, 34, 192, 158, 29, 67, 161, 255,
  42         70, 24, 250, 164, 39, 121, 155, 197, 132, 218, 56, 102, 229, 187, 89, 7,
  43         219, 133, 103, 57, 186, 228, 6, 88, 25, 71, 165, 251, 120, 38, 196, 154,
  44         101, 59, 217, 135, 4, 90, 184, 230, 167, 249, 27, 69, 198, 152, 122, 36,
  45         248, 166, 68, 26, 153, 199, 37, 123, 58, 100, 134, 216, 91, 5, 231, 185,
  46         140, 210, 48, 110, 237, 179, 81, 15, 78, 16, 242, 172, 47, 113, 147, 205,
  47         17, 79, 173, 243, 112, 46, 204, 146, 211, 141, 111, 49, 178, 236, 14, 80,
  48         175, 241, 19, 77, 206, 144, 114, 44, 109, 51, 209, 143, 12, 82, 176, 238,
  49         50, 108, 142, 208, 83, 13, 239, 177, 240, 174, 76, 18, 145, 207, 45, 115,
  50         202, 148, 118, 40, 171, 245, 23, 73, 8, 86, 180, 234, 105, 55, 213, 139,
  51         87, 9, 235, 181, 54, 104, 138, 212, 149, 203, 41, 119, 244, 170, 72, 22,
  52         233, 183, 85, 11, 136, 214, 52, 106, 43, 117, 151, 201, 74, 20, 246, 168,
  53         116, 42, 200, 150, 21, 75, 169, 247, 182, 232, 10, 84, 215, 137, 107, 53
  54 };
  55
  56 static void w1_delay(unsigned long tm)
  57 {
  58         udelay(tm * w1_delay_parm);
  59 }
  60
  61 static void w1_write_bit(struct w1_master *dev, int bit);
  62 static u8 w1_read_bit(struct w1_master *dev);
  63
  64 /**
  65  * Generates a write-0 or write-1 cycle and samples the level.
  66  */
  67 static u8 w1_touch_bit(struct w1_master *dev, int bit)
  68 {
  69         if (dev->bus_master->touch_bit)
  70                 return dev->bus_master->touch_bit(dev->bus_master->data, bit);
  71         else if (bit)
  72                 return w1_read_bit(dev);
  73         else {
  74                 w1_write_bit(dev, 0);
  75                 return 0;
  76         }
  77 }
  78
  79 /**
  80  * Generates a write-0 or write-1 cycle.
  81  * Only call if dev->bus_master->touch_bit is NULL
  82  */
  83 static void w1_write_bit(struct w1_master *dev, int bit)
  84 {
  85         unsigned long flags = 0;
  86
  87         if(w1_disable_irqs) local_irq_save(flags);
  88
  89         if (bit) {
  90                 dev->bus_master->write_bit(dev->bus_master->data, 0);
  91                 w1_delay(6);
  92                 dev->bus_master->write_bit(dev->bus_master->data, 1);
  93                 w1_delay(64);
  94         } else {
  95                 dev->bus_master->write_bit(dev->bus_master->data, 0);
  96                 w1_delay(60);
  97                 dev->bus_master->write_bit(dev->bus_master->data, 1);
  98                 w1_delay(10);
  99         }
 100
 101         if(w1_disable_irqs) local_irq_restore(flags);
 102 }
 103
 104 /**
 105  * Pre-write operation, currently only supporting strong pullups.
 106  * Program the hardware for a strong pullup, if one has been requested and
 107  * the hardware supports it.
 108  *
 109  * @param dev     the master device
 110  */
 111 static void w1_pre_write(struct w1_master *dev)
 112 {
 113         if (dev->pullup_duration &&
 114                 dev->enable_pullup && dev->bus_master->set_pullup) {
 115                 dev->bus_master->set_pullup(dev->bus_master->data,
 116                         dev->pullup_duration);
 117         }
 118 }
 119
 120 /**
 121  * Post-write operation, currently only supporting strong pullups.
 122  * If a strong pullup was requested, clear it if the hardware supports
 123  * them, or execute the delay otherwise, in either case clear the request.
 124  *
 125  * @param dev     the master device
 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  * Writes 8 bits.
 140  *
 141  * @param dev     the master device
 142  * @param byte    the byte to write
 143  */
 144 void w1_write_8(struct w1_master *dev, u8 byte)
 145 {
 146         int i;
 147
 148         if (dev->bus_master->write_byte) {
 149                 w1_pre_write(dev);
 150                 dev->bus_master->write_byte(dev->bus_master->data, byte);
 151         }
 152         else
 153                 for (i = 0; i < 8; ++i) {
 154                         if (i == 7)
 155                                 w1_pre_write(dev);
 156                         w1_touch_bit(dev, (byte >> i) & 0x1);
 157                 }
 158         w1_post_write(dev);
 159 }
 160 EXPORT_SYMBOL_GPL(w1_write_8);
 161
 162
 163 /**
 164  * Generates a write-1 cycle and samples the level.
 165  * Only call if dev->bus_master->touch_bit is NULL
 166  */
 167 static u8 w1_read_bit(struct w1_master *dev)
 168 {
 169         int result;
 170         unsigned long flags = 0;
 171
 172         /* sample timing is critical here */
 173         local_irq_save(flags);
 174         dev->bus_master->write_bit(dev->bus_master->data, 0);
 175         w1_delay(6);
 176         dev->bus_master->write_bit(dev->bus_master->data, 1);
 177         w1_delay(9);
 178
 179         result = dev->bus_master->read_bit(dev->bus_master->data);
 180         local_irq_restore(flags);
 181
 182         w1_delay(55);
 183
 184         return result & 0x1;
 185 }
 186
 187 /**
 188  * Does a triplet - used for searching ROM addresses.
 189  * Return bits:
 190  *  bit 0 = id_bit
 191  *  bit 1 = comp_bit
 192  *  bit 2 = dir_taken
 193  * If both bits 0 & 1 are set, the search should be restarted.
 194  *
 195  * @param dev     the master device
 196  * @param bdir    the bit to write if both id_bit and comp_bit are 0
 197  * @return        bit fields - see above
 198  */
 199 u8 w1_triplet(struct w1_master *dev, int bdir)
 200 {
 201         if (dev->bus_master->triplet)
 202                 return dev->bus_master->triplet(dev->bus_master->data, bdir);
 203         else {
 204                 u8 id_bit   = w1_touch_bit(dev, 1);
 205                 u8 comp_bit = w1_touch_bit(dev, 1);
 206                 u8 retval;
 207
 208                 if (id_bit && comp_bit)
 209                         return 0x03;  /* error */
 210
 211                 if (!id_bit && !comp_bit) {
 212                         /* Both bits are valid, take the direction given */
 213                         retval = bdir ? 0x04 : 0;
 214                 } else {
 215                         /* Only one bit is valid, take that direction */
 216                         bdir = id_bit;
 217                         retval = id_bit ? 0x05 : 0x02;
 218                 }
 219
 220                 if (dev->bus_master->touch_bit)
 221                         w1_touch_bit(dev, bdir);
 222                 else
 223                         w1_write_bit(dev, bdir);
 224                 return retval;
 225         }
 226 }
 227
 228 /**
 229  * Reads 8 bits.
 230  *
 231  * @param dev     the master device
 232  * @return        the byte read
 233  */
 234 u8 w1_read_8(struct w1_master *dev)
 235 {
 236         int i;
 237         u8 res = 0;
 238
 239         if (dev->bus_master->read_byte)
 240                 res = dev->bus_master->read_byte(dev->bus_master->data);
 241         else
 242                 for (i = 0; i < 8; ++i)
 243                         res |= (w1_touch_bit(dev,1) << i);
 244
 245         return res;
 246 }
 247 EXPORT_SYMBOL_GPL(w1_read_8);
 248
 249 /**
 250  * Writes a series of bytes.
 251  *
 252  * @param dev     the master device
 253  * @param buf     pointer to the data to write
 254  * @param len     the number of bytes to write
 255  */
 256 void w1_write_block(struct w1_master *dev, const u8 *buf, int len)
 257 {
 258         int i;
 259
 260         if (dev->bus_master->write_block) {
 261                 w1_pre_write(dev);
 262                 dev->bus_master->write_block(dev->bus_master->data, buf, len);
 263         }
 264         else
 265                 for (i = 0; i < len; ++i)
 266                         w1_write_8(dev, buf[i]); /* calls w1_pre_write */
 267         w1_post_write(dev);
 268 }
 269 EXPORT_SYMBOL_GPL(w1_write_block);
 270
 271 /**
 272  * Touches a series of bytes.
 273  *
 274  * @param dev     the master device
 275  * @param buf     pointer to the data to write
 276  * @param len     the number of bytes to write
 277  */
 278 void w1_touch_block(struct w1_master *dev, u8 *buf, int len)
 279 {
 280         int i, j;
 281         u8 tmp;
 282
 283         for (i = 0; i < len; ++i) {
 284                 tmp = 0;
 285                 for (j = 0; j < 8; ++j) {
 286                         if (j == 7)
 287                                 w1_pre_write(dev);
 288                         tmp |= w1_touch_bit(dev, (buf[i] >> j) & 0x1) << j;
 289                 }
 290
 291                 buf[i] = tmp;
 292         }
 293 }
 294 EXPORT_SYMBOL_GPL(w1_touch_block);
 295
 296 /**
 297  * Reads a series of bytes.
 298  *
 299  * @param dev     the master device
 300  * @param buf     pointer to the buffer to fill
 301  * @param 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  * Issues a reset bus sequence.
 323  *
 324  * @param  dev The bus master pointer
 325  * @return     0=Device present, 1=No device present or error
 326  */
 327 int w1_reset_bus(struct w1_master *dev)
 328 {
 329         int result;
 330         unsigned long flags = 0;
 331
 332         if(w1_disable_irqs) local_irq_save(flags);
 333
 334         if (dev->bus_master->reset_bus)
 335                 result = dev->bus_master->reset_bus(dev->bus_master->data) & 0x1;
 336         else {
 337                 dev->bus_master->write_bit(dev->bus_master->data, 0);
 338                 /* minimum 480, max ? us
 339                  * be nice and sleep, except 18b20 spec lists 960us maximum,
 340                  * so until we can sleep with microsecond accuracy, spin.
 341                  * Feel free to come up with some other way to give up the
 342                  * cpu for such a short amount of time AND get it back in
 343                  * the maximum amount of time.
 344                  */
 345                 w1_delay(500);
 346                 dev->bus_master->write_bit(dev->bus_master->data, 1);
 347                 w1_delay(70);
 348
 349                 result = dev->bus_master->read_bit(dev->bus_master->data) & 0x1;
 350                 /* minmum 70 (above) + 430 = 500 us
 351                  * There aren't any timing requirements between a reset and
 352                  * the following transactions.  Sleeping is safe here.
 353                  */
 354                 /* w1_delay(430); min required time */
 355                 msleep(1);
 356         }
 357
 358         if(w1_disable_irqs) local_irq_restore(flags);
 359
 360         return result;
 361 }
 362 EXPORT_SYMBOL_GPL(w1_reset_bus);
 363
 364 u8 w1_calc_crc8(u8 * data, int len)
 365 {
 366         u8 crc = 0;
 367
 368         while (len--)
 369                 crc = w1_crc8_table[crc ^ *data++];
 370
 371         return crc;
 372 }
 373 EXPORT_SYMBOL_GPL(w1_calc_crc8);
 374
 375 void w1_search_devices(struct w1_master *dev, u8 search_type, w1_slave_found_callback cb)
 376 {
 377         dev->attempts++;
 378         if (dev->bus_master->search)
 379                 dev->bus_master->search(dev->bus_master->data, dev,
 380                         search_type, cb);
 381         else
 382                 w1_search(dev, search_type, cb);
 383 }
 384
 385 /**
 386  * Resets the bus and then selects the slave by sending either a skip rom
 387  * or a rom match.
 388  * The w1 master lock must be held.
 389  *
 390  * @param sl    the slave to select
 391  * @return      0=success, anything else=error
 392  */
 393 int w1_reset_select_slave(struct w1_slave *sl)
 394 {
 395         if (w1_reset_bus(sl->master))
 396                 return -1;
 397
 398         if (sl->master->slave_count == 1)
 399                 w1_write_8(sl->master, W1_SKIP_ROM);
 400         else {
 401                 u8 match[9] = {W1_MATCH_ROM, };
 402                 u64 rn = le64_to_cpu(*((u64*)&sl->reg_num));
 403
 404                 memcpy(&match[1], &rn, 8);
 405                 w1_write_block(sl->master, match, 9);
 406         }
 407         return 0;
 408 }
 409 EXPORT_SYMBOL_GPL(w1_reset_select_slave);
 410
 411 /**
 412  * When the workflow with a slave amongst many requires several
 413  * successive commands a reset between each, this function is similar
 414  * to doing a reset then a match ROM for the last matched ROM. The
 415  * advantage being that the matched ROM step is skipped in favor of the
 416  * resume command. The slave must support the command of course.
 417  *
 418  * If the bus has only one slave, traditionnaly the match ROM is skipped
 419  * and a "SKIP ROM" is done for efficiency. On multi-slave busses, this
 420  * doesn't work of course, but the resume command is the next best thing.
 421  *
 422  * The w1 master lock must be held.
 423  *
 424  * @param dev     the master device
 425  */
 426 int w1_reset_resume_command(struct w1_master *dev)
 427 {
 428         if (w1_reset_bus(dev))
 429                 return -1;
 430
 431         /* This will make only the last matched slave perform a skip ROM. */
 432         w1_write_8(dev, W1_RESUME_CMD);
 433         return 0;
 434 }
 435 EXPORT_SYMBOL_GPL(w1_reset_resume_command);
 436
 437 /**
 438  * Put out a strong pull-up of the specified duration after the next write
 439  * operation.  Not all hardware supports strong pullups.  Hardware that
 440  * doesn't support strong pullups will sleep for the given time after the
 441  * write operation without a strong pullup.  This is a one shot request for
 442  * the next write, specifying zero will clear a previous request.
 443  * The w1 master lock must be held.
 444  *
 445  * @param delay time in milliseconds
 446  * @return      0=success, anything else=error
 447  */
 448 void w1_next_pullup(struct w1_master *dev, int delay)
 449 {
 450         dev->pullup_duration = delay;
 451 }
 452 EXPORT_SYMBOL_GPL(w1_next_pullup);