drivers/w1/slaves/w1_therm.c

   1 /*
   2  *      w1_therm.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 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 <zbr@ioremap.net>");
  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  * In case the parasite power-detection is not working (seems to be the case
  45  * for some DS18S20) the strong pullup can also be forced, regardless of the
  46  * power state of the devices.
  47  *
  48  * Summary of options:
  49  * - strong_pullup = 0  Disable strong pullup completely
  50  * - strong_pullup = 1  Enable automatic strong pullup detection
  51  * - strong_pullup = 2  Force strong pullup
  52  */
  53 static int w1_strong_pullup = 1;
  54 module_param_named(strong_pullup, w1_strong_pullup, int, 0);
  55
  56
  57 static ssize_t w1_therm_read(struct device *device,
  58         struct device_attribute *attr, char *buf);
  59
  60 static struct device_attribute w1_therm_attr =
  61         __ATTR(w1_slave, S_IRUGO, w1_therm_read, NULL);
  62
  63 static int w1_therm_add_slave(struct w1_slave *sl)
  64 {
  65         return device_create_file(&sl->dev, &w1_therm_attr);
  66 }
  67
  68 static void w1_therm_remove_slave(struct w1_slave *sl)
  69 {
  70         device_remove_file(&sl->dev, &w1_therm_attr);
  71 }
  72
  73 static struct w1_family_ops w1_therm_fops = {
  74         .add_slave      = w1_therm_add_slave,
  75         .remove_slave   = w1_therm_remove_slave,
  76 };
  77
  78 static struct w1_family w1_therm_family_DS18S20 = {
  79         .fid = W1_THERM_DS18S20,
  80         .fops = &w1_therm_fops,
  81 };
  82
  83 static struct w1_family w1_therm_family_DS18B20 = {
  84         .fid = W1_THERM_DS18B20,
  85         .fops = &w1_therm_fops,
  86 };
  87
  88 static struct w1_family w1_therm_family_DS1822 = {
  89         .fid = W1_THERM_DS1822,
  90         .fops = &w1_therm_fops,
  91 };
  92
  93 static struct w1_family w1_therm_family_DS28EA00 = {
  94         .fid = W1_THERM_DS28EA00,
  95         .fops = &w1_therm_fops,
  96 };
  97
  98 static struct w1_family w1_therm_family_DS1825 = {
  99         .fid = W1_THERM_DS1825,
 100         .fops = &w1_therm_fops,
 101 };
 102
 103 struct w1_therm_family_converter
 104 {
 105         u8                      broken;
 106         u16                     reserved;
 107         struct w1_family        *f;
 108         int                     (*convert)(u8 rom[9]);
 109 };
 110
 111 /* The return value is millidegrees Centigrade. */
 112 static inline int w1_DS18B20_convert_temp(u8 rom[9]);
 113 static inline int w1_DS18S20_convert_temp(u8 rom[9]);
 114
 115 static struct w1_therm_family_converter w1_therm_families[] = {
 116         {
 117                 .f              = &w1_therm_family_DS18S20,
 118                 .convert        = w1_DS18S20_convert_temp
 119         },
 120         {
 121                 .f              = &w1_therm_family_DS1822,
 122                 .convert        = w1_DS18B20_convert_temp
 123         },
 124         {
 125                 .f              = &w1_therm_family_DS18B20,
 126                 .convert        = w1_DS18B20_convert_temp
 127         },
 128         {
 129                 .f              = &w1_therm_family_DS28EA00,
 130                 .convert        = w1_DS18B20_convert_temp
 131         },
 132         {
 133                 .f              = &w1_therm_family_DS1825,
 134                 .convert        = w1_DS18B20_convert_temp
 135         }
 136 };
 137
 138 static inline int w1_DS18B20_convert_temp(u8 rom[9])
 139 {
 140         s16 t = le16_to_cpup((__le16 *)rom);
 141         return t*1000/16;
 142 }
 143
 144 static inline int w1_DS18S20_convert_temp(u8 rom[9])
 145 {
 146         int t, h;
 147
 148         if (!rom[7])
 149                 return 0;
 150
 151         if (rom[1] == 0)
 152                 t = ((s32)rom[0] >> 1)*1000;
 153         else
 154                 t = 1000*(-1*(s32)(0x100-rom[0]) >> 1);
 155
 156         t -= 250;
 157         h = 1000*((s32)rom[7] - (s32)rom[6]);
 158         h /= (s32)rom[7];
 159         t += h;
 160
 161         return t;
 162 }
 163
 164 static inline int w1_convert_temp(u8 rom[9], u8 fid)
 165 {
 166         int i;
 167
 168         for (i = 0; i < ARRAY_SIZE(w1_therm_families); ++i)
 169                 if (w1_therm_families[i].f->fid == fid)
 170                         return w1_therm_families[i].convert(rom);
 171
 172         return 0;
 173 }
 174
 175
 176 static ssize_t w1_therm_read(struct device *device,
 177         struct device_attribute *attr, char *buf)
 178 {
 179         struct w1_slave *sl = dev_to_w1_slave(device);
 180         struct w1_master *dev = sl->master;
 181         u8 rom[9], crc, verdict, external_power;
 182         int i, max_trying = 10;
 183         ssize_t c = PAGE_SIZE;
 184
 185         i = mutex_lock_interruptible(&dev->bus_mutex);
 186         if (i != 0)
 187                 return i;
 188
 189         memset(rom, 0, sizeof(rom));
 190
 191         while (max_trying--) {
 192
 193                 verdict = 0;
 194                 crc = 0;
 195
 196                 if (!w1_reset_select_slave(sl)) {
 197                         int count = 0;
 198                         unsigned int tm = 750;
 199                         unsigned long sleep_rem;
 200
 201                         w1_write_8(dev, W1_READ_PSUPPLY);
 202                         external_power = w1_read_8(dev);
 203
 204                         if (w1_reset_select_slave(sl))
 205                                 continue;
 206
 207                         /* 750ms strong pullup (or delay) after the convert */
 208                         if (w1_strong_pullup == 2 ||
 209                                         (!external_power && w1_strong_pullup))
 210                                 w1_next_pullup(dev, tm);
 211
 212                         w1_write_8(dev, W1_CONVERT_TEMP);
 213
 214                         if (external_power) {
 215                                 mutex_unlock(&dev->bus_mutex);
 216
 217                                 sleep_rem = msleep_interruptible(tm);
 218                                 if (sleep_rem != 0)
 219                                         return -EINTR;
 220
 221                                 i = mutex_lock_interruptible(&dev->bus_mutex);
 222                                 if (i != 0)
 223                                         return i;
 224                         } else if (!w1_strong_pullup) {
 225                                 sleep_rem = msleep_interruptible(tm);
 226                                 if (sleep_rem != 0) {
 227                                         mutex_unlock(&dev->bus_mutex);
 228                                         return -EINTR;
 229                                 }
 230                         }
 231
 232                         if (!w1_reset_select_slave(sl)) {
 233
 234                                 w1_write_8(dev, W1_READ_SCRATCHPAD);
 235                                 if ((count = w1_read_block(dev, rom, 9)) != 9) {
 236                                         dev_warn(device, "w1_read_block() "
 237                                                 "returned %u instead of 9.\n",
 238                                                 count);
 239                                 }
 240
 241                                 crc = w1_calc_crc8(rom, 8);
 242
 243                                 if (rom[8] == crc)
 244                                         verdict = 1;
 245                         }
 246                 }
 247
 248                 if (verdict)
 249                         break;
 250         }
 251
 252         for (i = 0; i < 9; ++i)
 253                 c -= snprintf(buf + PAGE_SIZE - c, c, "%02x ", rom[i]);
 254         c -= snprintf(buf + PAGE_SIZE - c, c, ": crc=%02x %s\n",
 255                            crc, (verdict) ? "YES" : "NO");
 256         if (verdict)
 257                 memcpy(sl->rom, rom, sizeof(sl->rom));
 258         else
 259                 dev_warn(device, "Read failed CRC check\n");
 260
 261         for (i = 0; i < 9; ++i)
 262                 c -= snprintf(buf + PAGE_SIZE - c, c, "%02x ", sl->rom[i]);
 263
 264         c -= snprintf(buf + PAGE_SIZE - c, c, "t=%d\n",
 265                 w1_convert_temp(rom, sl->family->fid));
 266         mutex_unlock(&dev->bus_mutex);
 267
 268         return PAGE_SIZE - c;
 269 }
 270
 271 static int __init w1_therm_init(void)
 272 {
 273         int err, i;
 274
 275         for (i = 0; i < ARRAY_SIZE(w1_therm_families); ++i) {
 276                 err = w1_register_family(w1_therm_families[i].f);
 277                 if (err)
 278                         w1_therm_families[i].broken = 1;
 279         }
 280
 281         return 0;
 282 }
 283
 284 static void __exit w1_therm_fini(void)
 285 {
 286         int i;
 287
 288         for (i = 0; i < ARRAY_SIZE(w1_therm_families); ++i)
 289                 if (!w1_therm_families[i].broken)
 290                         w1_unregister_family(w1_therm_families[i].f);
 291 }
 292
 293 module_init(w1_therm_init);
 294 module_exit(w1_therm_fini);