drivers/w1/w1_io.c

   1 /*
   2  *      w1_io.c
   3  *
   4  * Copyright (c) 2004 Evgeniy Polyakov <johnpol@2ka.mipt.ru>
   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
  27 #include "w1.h"
  28 #include "w1_log.h"
  29 #include "w1_io.h"
  30
  31 int w1_delay_parm = 1;
  32 module_param_named(delay_coef, w1_delay_parm, int, 0);
  33
  34 static u8 w1_crc8_table[] = {
  35         0, 94, 188, 226, 97, 63, 221, 131, 194, 156, 126, 32, 163, 253, 31, 65,
  36         157, 195, 33, 127, 252, 162, 64, 30, 95, 1, 227, 189, 62, 96, 130, 220,
  37         35, 125, 159, 193, 66, 28, 254, 160, 225, 191, 93, 3, 128, 222, 60, 98,
  38         190, 224, 2, 92, 223, 129, 99, 61, 124, 34, 192, 158, 29, 67, 161, 255,
  39         70, 24, 250, 164, 39, 121, 155, 197, 132, 218, 56, 102, 229, 187, 89, 7,
  40         219, 133, 103, 57, 186, 228, 6, 88, 25, 71, 165, 251, 120, 38, 196, 154,
  41         101, 59, 217, 135, 4, 90, 184, 230, 167, 249, 27, 69, 198, 152, 122, 36,
  42         248, 166, 68, 26, 153, 199, 37, 123, 58, 100, 134, 216, 91, 5, 231, 185,
  43         140, 210, 48, 110, 237, 179, 81, 15, 78, 16, 242, 172, 47, 113, 147, 205,
  44         17, 79, 173, 243, 112, 46, 204, 146, 211, 141, 111, 49, 178, 236, 14, 80,
  45         175, 241, 19, 77, 206, 144, 114, 44, 109, 51, 209, 143, 12, 82, 176, 238,
  46         50, 108, 142, 208, 83, 13, 239, 177, 240, 174, 76, 18, 145, 207, 45, 115,
  47         202, 148, 118, 40, 171, 245, 23, 73, 8, 86, 180, 234, 105, 55, 213, 139,
  48         87, 9, 235, 181, 54, 104, 138, 212, 149, 203, 41, 119, 244, 170, 72, 22,
  49         233, 183, 85, 11, 136, 214, 52, 106, 43, 117, 151, 201, 74, 20, 246, 168,
  50         116, 42, 200, 150, 21, 75, 169, 247, 182, 232, 10, 84, 215, 137, 107, 53
  51 };
  52
  53 void w1_delay(unsigned long tm)
  54 {
  55         udelay(tm * w1_delay_parm);
  56 }
  57
  58 static void w1_write_bit(struct w1_master *dev, int bit);
  59 static u8 w1_read_bit(struct w1_master *dev);
  60
  61 /**
  62  * Generates a write-0 or write-1 cycle and samples the level.
  63  */
  64 u8 w1_touch_bit(struct w1_master *dev, int bit)
  65 {
  66         if (dev->bus_master->touch_bit)
  67                 return dev->bus_master->touch_bit(dev->bus_master->data, bit);
  68         else if (bit)
  69                 return w1_read_bit(dev);
  70         else {
  71                 w1_write_bit(dev, 0);
  72                 return(0);
  73         }
  74 }
  75
  76 /**
  77  * Generates a write-0 or write-1 cycle.
  78  * Only call if dev->bus_master->touch_bit is NULL
  79  */
  80 static void w1_write_bit(struct w1_master *dev, int bit)
  81 {
  82         if (bit) {
  83                 dev->bus_master->write_bit(dev->bus_master->data, 0);
  84                 w1_delay(6);
  85                 dev->bus_master->write_bit(dev->bus_master->data, 1);
  86                 w1_delay(64);
  87         } else {
  88                 dev->bus_master->write_bit(dev->bus_master->data, 0);
  89                 w1_delay(60);
  90                 dev->bus_master->write_bit(dev->bus_master->data, 1);
  91                 w1_delay(10);
  92         }
  93 }
  94
  95 /**
  96  * Writes 8 bits.
  97  *
  98  * @param dev     the master device
  99  * @param byte    the byte to write
 100  */
 101 void w1_write_8(struct w1_master *dev, u8 byte)
 102 {
 103         int i;
 104
 105         if (dev->bus_master->write_byte)
 106                 dev->bus_master->write_byte(dev->bus_master->data, byte);
 107         else
 108                 for (i = 0; i < 8; ++i)
 109                         w1_touch_bit(dev, (byte >> i) & 0x1);
 110 }
 111
 112
 113 /**
 114  * Generates a write-1 cycle and samples the level.
 115  * Only call if dev->bus_master->touch_bit is NULL
 116  */
 117 static u8 w1_read_bit(struct w1_master *dev)
 118 {
 119         int result;
 120
 121         dev->bus_master->write_bit(dev->bus_master->data, 0);
 122         w1_delay(6);
 123         dev->bus_master->write_bit(dev->bus_master->data, 1);
 124         w1_delay(9);
 125
 126         result = dev->bus_master->read_bit(dev->bus_master->data);
 127         w1_delay(55);
 128
 129         return result & 0x1;
 130 }
 131
 132 /**
 133  * Does a triplet - used for searching ROM addresses.
 134  * Return bits:
 135  *  bit 0 = id_bit
 136  *  bit 1 = comp_bit
 137  *  bit 2 = dir_taken
 138  * If both bits 0 & 1 are set, the search should be restarted.
 139  *
 140  * @param dev     the master device
 141  * @param bdir    the bit to write if both id_bit and comp_bit are 0
 142  * @return        bit fields - see above
 143  */
 144 u8 w1_triplet(struct w1_master *dev, int bdir)
 145 {
 146         if ( dev->bus_master->triplet )
 147                 return(dev->bus_master->triplet(dev->bus_master->data, bdir));
 148         else {
 149                 u8 id_bit   = w1_touch_bit(dev, 1);
 150                 u8 comp_bit = w1_touch_bit(dev, 1);
 151                 u8 retval;
 152
 153                 if ( id_bit && comp_bit )
 154                         return(0x03);  /* error */
 155
 156                 if ( !id_bit && !comp_bit ) {
 157                         /* Both bits are valid, take the direction given */
 158                         retval = bdir ? 0x04 : 0;
 159                 } else {
 160                         /* Only one bit is valid, take that direction */
 161                         bdir = id_bit;
 162                         retval = id_bit ? 0x05 : 0x02;
 163                 }
 164
 165                 if ( dev->bus_master->touch_bit )
 166                         w1_touch_bit(dev, bdir);
 167                 else
 168                         w1_write_bit(dev, bdir);
 169                 return(retval);
 170         }
 171 }
 172
 173 /**
 174  * Reads 8 bits.
 175  *
 176  * @param dev     the master device
 177  * @return        the byte read
 178  */
 179 u8 w1_read_8(struct w1_master * dev)
 180 {
 181         int i;
 182         u8 res = 0;
 183
 184         if (dev->bus_master->read_byte)
 185                 res = dev->bus_master->read_byte(dev->bus_master->data);
 186         else
 187                 for (i = 0; i < 8; ++i)
 188                         res |= (w1_touch_bit(dev,1) << i);
 189
 190         return res;
 191 }
 192
 193 /**
 194  * Writes a series of bytes.
 195  *
 196  * @param dev     the master device
 197  * @param buf     pointer to the data to write
 198  * @param len     the number of bytes to write
 199  * @return        the byte read
 200  */
 201 void w1_write_block(struct w1_master *dev, const u8 *buf, int len)
 202 {
 203         int i;
 204
 205         if (dev->bus_master->write_block)
 206                 dev->bus_master->write_block(dev->bus_master->data, buf, len);
 207         else
 208                 for (i = 0; i < len; ++i)
 209                         w1_write_8(dev, buf[i]);
 210 }
 211
 212 /**
 213  * Reads a series of bytes.
 214  *
 215  * @param dev     the master device
 216  * @param buf     pointer to the buffer to fill
 217  * @param len     the number of bytes to read
 218  * @return        the number of bytes read
 219  */
 220 u8 w1_read_block(struct w1_master *dev, u8 *buf, int len)
 221 {
 222         int i;
 223         u8 ret;
 224
 225         if (dev->bus_master->read_block)
 226                 ret = dev->bus_master->read_block(dev->bus_master->data, buf, len);
 227         else {
 228                 for (i = 0; i < len; ++i)
 229                         buf[i] = w1_read_8(dev);
 230                 ret = len;
 231         }
 232
 233         return ret;
 234 }
 235
 236 /**
 237  * Issues a reset bus sequence.
 238  *
 239  * @param  dev The bus master pointer
 240  * @return     0=Device present, 1=No device present or error
 241  */
 242 int w1_reset_bus(struct w1_master *dev)
 243 {
 244         int result;
 245
 246         if (dev->bus_master->reset_bus)
 247                 result = dev->bus_master->reset_bus(dev->bus_master->data) & 0x1;
 248         else {
 249                 dev->bus_master->write_bit(dev->bus_master->data, 0);
 250                 w1_delay(480);
 251                 dev->bus_master->write_bit(dev->bus_master->data, 1);
 252                 w1_delay(70);
 253
 254                 result = dev->bus_master->read_bit(dev->bus_master->data) & 0x1;
 255                 w1_delay(410);
 256         }
 257
 258         return result;
 259 }
 260
 261 u8 w1_calc_crc8(u8 * data, int len)
 262 {
 263         u8 crc = 0;
 264
 265         while (len--)
 266                 crc = w1_crc8_table[crc ^ *data++];
 267
 268         return crc;
 269 }
 270
 271 void w1_search_devices(struct w1_master *dev, w1_slave_found_callback cb)
 272 {
 273         dev->attempts++;
 274         if (dev->bus_master->search)
 275                 dev->bus_master->search(dev->bus_master->data, cb);
 276         else
 277                 w1_search(dev, cb);
 278 }
 279
 280 /**
 281  * Resets the bus and then selects the slave by sending either a skip rom
 282  * or a rom match.
 283  * The w1 master lock must be held.
 284  *
 285  * @param sl    the slave to select
 286  * @return      0=success, anything else=error
 287  */
 288 int w1_reset_select_slave(struct w1_slave *sl)
 289 {
 290         if (w1_reset_bus(sl->master))
 291                 return -1;
 292
 293         if (sl->master->slave_count == 1)
 294                 w1_write_8(sl->master, W1_SKIP_ROM);
 295         else {
 296                 u8 match[9] = {W1_MATCH_ROM, };
 297                 memcpy(&match[1], (u8 *)&sl->reg_num, 8);
 298                 w1_write_block(sl->master, match, 9);
 299         }
 300         return 0;
 301 }
 302
 303 EXPORT_SYMBOL(w1_touch_bit);
 304 EXPORT_SYMBOL(w1_write_8);
 305 EXPORT_SYMBOL(w1_read_8);
 306 EXPORT_SYMBOL(w1_reset_bus);
 307 EXPORT_SYMBOL(w1_calc_crc8);
 308 EXPORT_SYMBOL(w1_delay);
 309 EXPORT_SYMBOL(w1_read_block);
 310 EXPORT_SYMBOL(w1_write_block);
 311 EXPORT_SYMBOL(w1_search_devices);
 312 EXPORT_SYMBOL(w1_reset_select_slave);