drivers/w1/slaves/w1_therm.c

   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(struct device *device,
  54         struct device_attribute *attr, char *buf);
  55
  56 static struct device_attribute w1_therm_attr =
  57         __ATTR(w1_slave, S_IRUGO, w1_therm_read, NULL);
  58
  59 static int w1_therm_add_slave(struct w1_slave *sl)
  60 {
  61         return device_create_file(&sl->dev, &w1_therm_attr);
  62 }
  63
  64 static void w1_therm_remove_slave(struct w1_slave *sl)
  65 {
  66         device_remove_file(&sl->dev, &w1_therm_attr);
  67 }
  68
  69 static struct w1_family_ops w1_therm_fops = {
  70         .add_slave      = w1_therm_add_slave,
  71         .remove_slave   = w1_therm_remove_slave,
  72 };
  73
  74 static struct w1_family w1_therm_family_DS18S20 = {
  75         .fid = W1_THERM_DS18S20,
  76         .fops = &w1_therm_fops,
  77 };
  78
  79 static struct w1_family w1_therm_family_DS18B20 = {
  80         .fid = W1_THERM_DS18B20,
  81         .fops = &w1_therm_fops,
  82 };
  83
  84 static struct w1_family w1_therm_family_DS1822 = {
  85         .fid = W1_THERM_DS1822,
  86         .fops = &w1_therm_fops,
  87 };
  88
  89 struct w1_therm_family_converter
  90 {
  91         u8                      broken;
  92         u16                     reserved;
  93         struct w1_family        *f;
  94         int                     (*convert)(u8 rom[9]);
  95 };
  96
  97 /* The return value is millidegrees Centigrade. */
  98 static inline int w1_DS18B20_convert_temp(u8 rom[9]);
  99 static inline int w1_DS18S20_convert_temp(u8 rom[9]);
 100
 101 static struct w1_therm_family_converter w1_therm_families[] = {
 102         {
 103                 .f              = &w1_therm_family_DS18S20,
 104                 .convert        = w1_DS18S20_convert_temp
 105         },
 106         {
 107                 .f              = &w1_therm_family_DS1822,
 108                 .convert        = w1_DS18B20_convert_temp
 109         },
 110         {
 111                 .f              = &w1_therm_family_DS18B20,
 112                 .convert        = w1_DS18B20_convert_temp
 113         },
 114 };
 115
 116 static inline int w1_DS18B20_convert_temp(u8 rom[9])
 117 {
 118         int t = ((s16)rom[1] << 8) | rom[0];
 119         t = t*1000/16;
 120         return t;
 121 }
 122
 123 static inline int w1_DS18S20_convert_temp(u8 rom[9])
 124 {
 125         int t, h;
 126
 127         if (!rom[7])
 128                 return 0;
 129
 130         if (rom[1] == 0)
 131                 t = ((s32)rom[0] >> 1)*1000;
 132         else
 133                 t = 1000*(-1*(s32)(0x100-rom[0]) >> 1);
 134
 135         t -= 250;
 136         h = 1000*((s32)rom[7] - (s32)rom[6]);
 137         h /= (s32)rom[7];
 138         t += h;
 139
 140         return t;
 141 }
 142
 143 static inline int w1_convert_temp(u8 rom[9], u8 fid)
 144 {
 145         int i;
 146
 147         for (i = 0; i < ARRAY_SIZE(w1_therm_families); ++i)
 148                 if (w1_therm_families[i].f->fid == fid)
 149                         return w1_therm_families[i].convert(rom);
 150
 151         return 0;
 152 }
 153
 154 static int w1_therm_check_rom(u8 rom[9])
 155 {
 156         int i;
 157
 158         for (i=0; i<sizeof(bad_roms)/9; ++i)
 159                 if (!memcmp(bad_roms[i], rom, 9))
 160                         return 1;
 161
 162         return 0;
 163 }
 164
 165 static ssize_t w1_therm_read(struct device *device,
 166         struct device_attribute *attr, char *buf)
 167 {
 168         struct w1_slave *sl = dev_to_w1_slave(device);
 169         struct w1_master *dev = sl->master;
 170         u8 rom[9], crc, verdict;
 171         int i, max_trying = 10;
 172         ssize_t c = PAGE_SIZE;
 173
 174         mutex_lock(&dev->mutex);
 175
 176         memset(rom, 0, sizeof(rom));
 177
 178         verdict = 0;
 179         crc = 0;
 180
 181         while (max_trying--) {
 182                 if (!w1_reset_select_slave(sl)) {
 183                         int count = 0;
 184                         unsigned int tm = 750;
 185
 186                         /* 750ms strong pullup (or delay) after the convert */
 187                         if (w1_strong_pullup)
 188                                 w1_next_pullup(dev, tm);
 189                         w1_write_8(dev, W1_CONVERT_TEMP);
 190                         if (!w1_strong_pullup)
 191                                 msleep(tm);
 192
 193                         if (!w1_reset_select_slave(sl)) {
 194
 195                                 w1_write_8(dev, W1_READ_SCRATCHPAD);
 196                                 if ((count = w1_read_block(dev, rom, 9)) != 9) {
 197                                         dev_warn(device, "w1_read_block() "
 198                                                 "returned %u instead of 9.\n",
 199                                                 count);
 200                                 }
 201
 202                                 crc = w1_calc_crc8(rom, 8);
 203
 204                                 if (rom[8] == crc)
 205                                         verdict = 1;
 206                         }
 207                 }
 208
 209                 if (!w1_therm_check_rom(rom))
 210                         break;
 211         }
 212
 213         for (i = 0; i < 9; ++i)
 214                 c -= snprintf(buf + PAGE_SIZE - c, c, "%02x ", rom[i]);
 215         c -= snprintf(buf + PAGE_SIZE - c, c, ": crc=%02x %s\n",
 216                            crc, (verdict) ? "YES" : "NO");
 217         if (verdict)
 218                 memcpy(sl->rom, rom, sizeof(sl->rom));
 219         else
 220                 dev_warn(device, "18S20 doesn't respond to CONVERT_TEMP.\n");
 221
 222         for (i = 0; i < 9; ++i)
 223                 c -= snprintf(buf + PAGE_SIZE - c, c, "%02x ", sl->rom[i]);
 224
 225         c -= snprintf(buf + PAGE_SIZE - c, c, "t=%d\n",
 226                 w1_convert_temp(rom, sl->family->fid));
 227         mutex_unlock(&dev->mutex);
 228
 229         return PAGE_SIZE - c;
 230 }
 231
 232 static int __init w1_therm_init(void)
 233 {
 234         int err, i;
 235
 236         for (i = 0; i < ARRAY_SIZE(w1_therm_families); ++i) {
 237                 err = w1_register_family(w1_therm_families[i].f);
 238                 if (err)
 239                         w1_therm_families[i].broken = 1;
 240         }
 241
 242         return 0;
 243 }
 244
 245 static void __exit w1_therm_fini(void)
 246 {
 247         int i;
 248
 249         for (i = 0; i < ARRAY_SIZE(w1_therm_families); ++i)
 250                 if (!w1_therm_families[i].broken)
 251                         w1_unregister_family(w1_therm_families[i].f);
 252 }
 253
 254 module_init(w1_therm_init);
 255 module_exit(w1_therm_fini);