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   1 /*
   2  *      w1_therm.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 therms 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/types.h>
  23
  24 #include <linux/kernel.h>
  25 #include <linux/module.h>
  26 #include <linux/moduleparam.h>
  27 #include <linux/sched.h>
  28 #include <linux/device.h>
  29 #include <linux/types.h>
  30 #include <linux/delay.h>
  31
  32 #include "../w1.h"
  33 #include "../w1_int.h"
  34 #include "../w1_family.h"
  35
  36 MODULE_LICENSE("GPL");
  37 MODULE_AUTHOR("Evgeniy Polyakov <johnpol@2ka.mipt.ru>");
  38 MODULE_DESCRIPTION("Driver for 1-wire Dallas network protocol, temperature family.");
  39
  40 /* Allow the strong pullup to be disabled, but default to enabled.
  41  * If it was disabled a parasite powered device might not get the require
  42  * current to do a temperature conversion.  If it is enabled parasite powered
  43  * devices have a better chance of getting the current required.
  44  */
  45 static int w1_strong_pullup = 1;
  46 module_param_named(strong_pullup, w1_strong_pullup, int, 0);
  47
  48 static u8 bad_roms[][9] = {
  49                                 {0xaa, 0x00, 0x4b, 0x46, 0xff, 0xff, 0x0c, 0x10, 0x87},
  50                                 {}
  51                         };
  52
  53 static ssize_t w1_therm_read_bin(struct kobject *, struct bin_attribute *,
  54                                  char *, loff_t, size_t);
  55
  56 static struct bin_attribute w1_therm_bin_attr = {
  57         .attr = {
  58                 .name = "w1_slave",
  59                 .mode = S_IRUGO,
  60         },
  61         .size = W1_SLAVE_DATA_SIZE,
  62         .read = w1_therm_read_bin,
  63 };
  64
  65 static int w1_therm_add_slave(struct w1_slave *sl)
  66 {
  67         return sysfs_create_bin_file(&sl->dev.kobj, &w1_therm_bin_attr);
  68 }
  69
  70 static void w1_therm_remove_slave(struct w1_slave *sl)
  71 {
  72         sysfs_remove_bin_file(&sl->dev.kobj, &w1_therm_bin_attr);
  73 }
  74
  75 static struct w1_family_ops w1_therm_fops = {
  76         .add_slave      = w1_therm_add_slave,
  77         .remove_slave   = w1_therm_remove_slave,
  78 };
  79
  80 static struct w1_family w1_therm_family_DS18S20 = {
  81         .fid = W1_THERM_DS18S20,
  82         .fops = &w1_therm_fops,
  83 };
  84
  85 static struct w1_family w1_therm_family_DS18B20 = {
  86         .fid = W1_THERM_DS18B20,
  87         .fops = &w1_therm_fops,
  88 };
  89
  90 static struct w1_family w1_therm_family_DS1822 = {
  91         .fid = W1_THERM_DS1822,
  92         .fops = &w1_therm_fops,
  93 };
  94
  95 struct w1_therm_family_converter
  96 {
  97         u8                      broken;
  98         u16                     reserved;
  99         struct w1_family        *f;
 100         int                     (*convert)(u8 rom[9]);
 101 };
 102
 103 /* The return value is millidegrees Centigrade. */
 104 static inline int w1_DS18B20_convert_temp(u8 rom[9]);
 105 static inline int w1_DS18S20_convert_temp(u8 rom[9]);
 106
 107 static struct w1_therm_family_converter w1_therm_families[] = {
 108         {
 109                 .f              = &w1_therm_family_DS18S20,
 110                 .convert        = w1_DS18S20_convert_temp
 111         },
 112         {
 113                 .f              = &w1_therm_family_DS1822,
 114                 .convert        = w1_DS18B20_convert_temp
 115         },
 116         {
 117                 .f              = &w1_therm_family_DS18B20,
 118                 .convert        = w1_DS18B20_convert_temp
 119         },
 120 };
 121
 122 static inline int w1_DS18B20_convert_temp(u8 rom[9])
 123 {
 124         s16 t = (rom[1] << 8) | rom[0];
 125         t = t*1000/16;
 126         return t;
 127 }
 128
 129 static inline int w1_DS18S20_convert_temp(u8 rom[9])
 130 {
 131         int t, h;
 132
 133         if (!rom[7])
 134                 return 0;
 135
 136         if (rom[1] == 0)
 137                 t = ((s32)rom[0] >> 1)*1000;
 138         else
 139                 t = 1000*(-1*(s32)(0x100-rom[0]) >> 1);
 140
 141         t -= 250;
 142         h = 1000*((s32)rom[7] - (s32)rom[6]);
 143         h /= (s32)rom[7];
 144         t += h;
 145
 146         return t;
 147 }
 148
 149 static inline int w1_convert_temp(u8 rom[9], u8 fid)
 150 {
 151         int i;
 152
 153         for (i = 0; i < ARRAY_SIZE(w1_therm_families); ++i)
 154                 if (w1_therm_families[i].f->fid == fid)
 155                         return w1_therm_families[i].convert(rom);
 156
 157         return 0;
 158 }
 159
 160 static int w1_therm_check_rom(u8 rom[9])
 161 {
 162         int i;
 163
 164         for (i=0; i<sizeof(bad_roms)/9; ++i)
 165                 if (!memcmp(bad_roms[i], rom, 9))
 166                         return 1;
 167
 168         return 0;
 169 }
 170
 171 static ssize_t w1_therm_read_bin(struct kobject *kobj,
 172                                  struct bin_attribute *bin_attr,
 173                                  char *buf, loff_t off, size_t count)
 174 {
 175         struct w1_slave *sl = kobj_to_w1_slave(kobj);
 176         struct w1_master *dev = sl->master;
 177         u8 rom[9], crc, verdict;
 178         int i, max_trying = 10;
 179
 180         mutex_lock(&sl->master->mutex);
 181
 182         if (off > W1_SLAVE_DATA_SIZE) {
 183                 count = 0;
 184                 goto out;
 185         }
 186         if (off + count > W1_SLAVE_DATA_SIZE) {
 187                 count = 0;
 188                 goto out;
 189         }
 190
 191         memset(buf, 0, count);
 192         memset(rom, 0, sizeof(rom));
 193
 194         count = 0;
 195         verdict = 0;
 196         crc = 0;
 197
 198         while (max_trying--) {
 199                 if (!w1_reset_select_slave(sl)) {
 200                         int count = 0;
 201                         unsigned int tm = 750;
 202
 203                         /* 750ms strong pullup (or delay) after the convert */
 204                         if (w1_strong_pullup)
 205                                 w1_next_pullup(dev, tm);
 206                         w1_write_8(dev, W1_CONVERT_TEMP);
 207                         if (!w1_strong_pullup)
 208                                 msleep(tm);
 209
 210                         if (!w1_reset_select_slave(sl)) {
 211
 212                                 w1_write_8(dev, W1_READ_SCRATCHPAD);
 213                                 if ((count = w1_read_block(dev, rom, 9)) != 9) {
 214                                         dev_warn(&dev->dev, "w1_read_block() returned %d instead of 9.\n", count);
 215                                 }
 216
 217                                 crc = w1_calc_crc8(rom, 8);
 218
 219                                 if (rom[8] == crc)
 220                                         verdict = 1;
 221                         }
 222                 }
 223
 224                 if (!w1_therm_check_rom(rom))
 225                         break;
 226         }
 227
 228         for (i = 0; i < 9; ++i)
 229                 count += sprintf(buf + count, "%02x ", rom[i]);
 230         count += sprintf(buf + count, ": crc=%02x %s\n",
 231                            crc, (verdict) ? "YES" : "NO");
 232         if (verdict)
 233                 memcpy(sl->rom, rom, sizeof(sl->rom));
 234         else
 235                 dev_warn(&dev->dev, "18S20 doesn't respond to CONVERT_TEMP.\n");
 236
 237         for (i = 0; i < 9; ++i)
 238                 count += sprintf(buf + count, "%02x ", sl->rom[i]);
 239
 240         count += sprintf(buf + count, "t=%d\n", w1_convert_temp(rom, sl->family->fid));
 241 out:
 242         mutex_unlock(&dev->mutex);
 243
 244         return count;
 245 }
 246
 247 static int __init w1_therm_init(void)
 248 {
 249         int err, i;
 250
 251         for (i = 0; i < ARRAY_SIZE(w1_therm_families); ++i) {
 252                 err = w1_register_family(w1_therm_families[i].f);
 253                 if (err)
 254                         w1_therm_families[i].broken = 1;
 255         }
 256
 257         return 0;
 258 }
 259
 260 static void __exit w1_therm_fini(void)
 261 {
 262         int i;
 263
 264         for (i = 0; i < ARRAY_SIZE(w1_therm_families); ++i)
 265                 if (!w1_therm_families[i].broken)
 266                         w1_unregister_family(w1_therm_families[i].f);
 267 }
 268
 269 module_init(w1_therm_init);
 270 module_exit(w1_therm_fini);