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 MODULE_ALIAS("w1-family-" __stringify(W1_THERM_DS18S20));
  40 MODULE_ALIAS("w1-family-" __stringify(W1_THERM_DS1822));
  41 MODULE_ALIAS("w1-family-" __stringify(W1_THERM_DS18B20));
  42 MODULE_ALIAS("w1-family-" __stringify(W1_THERM_DS1825));
  43 MODULE_ALIAS("w1-family-" __stringify(W1_THERM_DS28EA00));
  44
  45 /* Allow the strong pullup to be disabled, but default to enabled.
  46  * If it was disabled a parasite powered device might not get the require
  47  * current to do a temperature conversion.  If it is enabled parasite powered
  48  * devices have a better chance of getting the current required.
  49  * In case the parasite power-detection is not working (seems to be the case
  50  * for some DS18S20) the strong pullup can also be forced, regardless of the
  51  * power state of the devices.
  52  *
  53  * Summary of options:
  54  * - strong_pullup = 0  Disable strong pullup completely
  55  * - strong_pullup = 1  Enable automatic strong pullup detection
  56  * - strong_pullup = 2  Force strong pullup
  57  */
  58 static int w1_strong_pullup = 1;
  59 module_param_named(strong_pullup, w1_strong_pullup, int, 0);
  60
  61
  62 static ssize_t w1_slave_show(struct device *device,
  63         struct device_attribute *attr, char *buf);
  64
  65 static DEVICE_ATTR_RO(w1_slave);
  66
  67 static struct attribute *w1_therm_attrs[] = {
  68         &dev_attr_w1_slave.attr,
  69         NULL,
  70 };
  71 ATTRIBUTE_GROUPS(w1_therm);
  72
  73 static struct w1_family_ops w1_therm_fops = {
  74         .groups         = w1_therm_groups,
  75 };
  76
  77 static struct w1_family w1_therm_family_DS18S20 = {
  78         .fid = W1_THERM_DS18S20,
  79         .fops = &w1_therm_fops,
  80 };
  81
  82 static struct w1_family w1_therm_family_DS18B20 = {
  83         .fid = W1_THERM_DS18B20,
  84         .fops = &w1_therm_fops,
  85 };
  86
  87 static struct w1_family w1_therm_family_DS1822 = {
  88         .fid = W1_THERM_DS1822,
  89         .fops = &w1_therm_fops,
  90 };
  91
  92 static struct w1_family w1_therm_family_DS28EA00 = {
  93         .fid = W1_THERM_DS28EA00,
  94         .fops = &w1_therm_fops,
  95 };
  96
  97 static struct w1_family w1_therm_family_DS1825 = {
  98         .fid = W1_THERM_DS1825,
  99         .fops = &w1_therm_fops,
 100 };
 101
 102 struct w1_therm_family_converter
 103 {
 104         u8                      broken;
 105         u16                     reserved;
 106         struct w1_family        *f;
 107         int                     (*convert)(u8 rom[9]);
 108 };
 109
 110 /* The return value is millidegrees Centigrade. */
 111 static inline int w1_DS18B20_convert_temp(u8 rom[9]);
 112 static inline int w1_DS18S20_convert_temp(u8 rom[9]);
 113
 114 static struct w1_therm_family_converter w1_therm_families[] = {
 115         {
 116                 .f              = &w1_therm_family_DS18S20,
 117                 .convert        = w1_DS18S20_convert_temp
 118         },
 119         {
 120                 .f              = &w1_therm_family_DS1822,
 121                 .convert        = w1_DS18B20_convert_temp
 122         },
 123         {
 124                 .f              = &w1_therm_family_DS18B20,
 125                 .convert        = w1_DS18B20_convert_temp
 126         },
 127         {
 128                 .f              = &w1_therm_family_DS28EA00,
 129                 .convert        = w1_DS18B20_convert_temp
 130         },
 131         {
 132                 .f              = &w1_therm_family_DS1825,
 133                 .convert        = w1_DS18B20_convert_temp
 134         }
 135 };
 136
 137 static inline int w1_DS18B20_convert_temp(u8 rom[9])
 138 {
 139         s16 t = le16_to_cpup((__le16 *)rom);
 140         return t*1000/16;
 141 }
 142
 143 static inline int w1_DS18S20_convert_temp(u8 rom[9])
 144 {
 145         int t, h;
 146
 147         if (!rom[7])
 148                 return 0;
 149
 150         if (rom[1] == 0)
 151                 t = ((s32)rom[0] >> 1)*1000;
 152         else
 153                 t = 1000*(-1*(s32)(0x100-rom[0]) >> 1);
 154
 155         t -= 250;
 156         h = 1000*((s32)rom[7] - (s32)rom[6]);
 157         h /= (s32)rom[7];
 158         t += h;
 159
 160         return t;
 161 }
 162
 163 static inline int w1_convert_temp(u8 rom[9], u8 fid)
 164 {
 165         int i;
 166
 167         for (i = 0; i < ARRAY_SIZE(w1_therm_families); ++i)
 168                 if (w1_therm_families[i].f->fid == fid)
 169                         return w1_therm_families[i].convert(rom);
 170
 171         return 0;
 172 }
 173
 174
 175 static ssize_t w1_slave_show(struct device *device,
 176         struct device_attribute *attr, char *buf)
 177 {
 178         struct w1_slave *sl = dev_to_w1_slave(device);
 179         struct w1_master *dev = sl->master;
 180         u8 rom[9], crc, verdict, external_power;
 181         int i, max_trying = 10;
 182         ssize_t c = PAGE_SIZE;
 183
 184         i = mutex_lock_interruptible(&dev->bus_mutex);
 185         if (i != 0)
 186                 return i;
 187
 188         memset(rom, 0, sizeof(rom));
 189
 190         while (max_trying--) {
 191
 192                 verdict = 0;
 193                 crc = 0;
 194
 195                 if (!w1_reset_select_slave(sl)) {
 196                         int count = 0;
 197                         unsigned int tm = 750;
 198                         unsigned long sleep_rem;
 199
 200                         w1_write_8(dev, W1_READ_PSUPPLY);
 201                         external_power = w1_read_8(dev);
 202
 203                         if (w1_reset_select_slave(sl))
 204                                 continue;
 205
 206                         /* 750ms strong pullup (or delay) after the convert */
 207                         if (w1_strong_pullup == 2 ||
 208                                         (!external_power && w1_strong_pullup))
 209                                 w1_next_pullup(dev, tm);
 210
 211                         w1_write_8(dev, W1_CONVERT_TEMP);
 212
 213                         if (external_power) {
 214                                 mutex_unlock(&dev->bus_mutex);
 215
 216                                 sleep_rem = msleep_interruptible(tm);
 217                                 if (sleep_rem != 0)
 218                                         return -EINTR;
 219
 220                                 i = mutex_lock_interruptible(&dev->bus_mutex);
 221                                 if (i != 0)
 222                                         return i;
 223                         } else if (!w1_strong_pullup) {
 224                                 sleep_rem = msleep_interruptible(tm);
 225                                 if (sleep_rem != 0) {
 226                                         mutex_unlock(&dev->bus_mutex);
 227                                         return -EINTR;
 228                                 }
 229                         }
 230
 231                         if (!w1_reset_select_slave(sl)) {
 232
 233                                 w1_write_8(dev, W1_READ_SCRATCHPAD);
 234                                 if ((count = w1_read_block(dev, rom, 9)) != 9) {
 235                                         dev_warn(device, "w1_read_block() "
 236                                                 "returned %u instead of 9.\n",
 237                                                 count);
 238                                 }
 239
 240                                 crc = w1_calc_crc8(rom, 8);
 241
 242                                 if (rom[8] == crc)
 243                                         verdict = 1;
 244                         }
 245                 }
 246
 247                 if (verdict)
 248                         break;
 249         }
 250
 251         for (i = 0; i < 9; ++i)
 252                 c -= snprintf(buf + PAGE_SIZE - c, c, "%02x ", rom[i]);
 253         c -= snprintf(buf + PAGE_SIZE - c, c, ": crc=%02x %s\n",
 254                            crc, (verdict) ? "YES" : "NO");
 255         if (verdict)
 256                 memcpy(sl->rom, rom, sizeof(sl->rom));
 257         else
 258                 dev_warn(device, "Read failed CRC check\n");
 259
 260         for (i = 0; i < 9; ++i)
 261                 c -= snprintf(buf + PAGE_SIZE - c, c, "%02x ", sl->rom[i]);
 262
 263         c -= snprintf(buf + PAGE_SIZE - c, c, "t=%d\n",
 264                 w1_convert_temp(rom, sl->family->fid));
 265         mutex_unlock(&dev->bus_mutex);
 266
 267         return PAGE_SIZE - c;
 268 }
 269
 270 static int __init w1_therm_init(void)
 271 {
 272         int err, i;
 273
 274         for (i = 0; i < ARRAY_SIZE(w1_therm_families); ++i) {
 275                 err = w1_register_family(w1_therm_families[i].f);
 276                 if (err)
 277                         w1_therm_families[i].broken = 1;
 278         }
 279
 280         return 0;
 281 }
 282
 283 static void __exit w1_therm_fini(void)
 284 {
 285         int i;
 286
 287         for (i = 0; i < ARRAY_SIZE(w1_therm_families); ++i)
 288                 if (!w1_therm_families[i].broken)
 289                         w1_unregister_family(w1_therm_families[i].f);
 290 }
 291
 292 module_init(w1_therm_init);
 293 module_exit(w1_therm_fini);