kernel/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/slab.h>
  31 #include <linux/delay.h>
  32
  33 #include "../w1.h"
  34 #include "../w1_int.h"
  35 #include "../w1_family.h"
  36
  37 MODULE_LICENSE("GPL");
  38 MODULE_AUTHOR("Evgeniy Polyakov <zbr@ioremap.net>");
  39 MODULE_DESCRIPTION("Driver for 1-wire Dallas network protocol, temperature family.");
  40 MODULE_ALIAS("w1-family-" __stringify(W1_THERM_DS18S20));
  41 MODULE_ALIAS("w1-family-" __stringify(W1_THERM_DS1822));
  42 MODULE_ALIAS("w1-family-" __stringify(W1_THERM_DS18B20));
  43 MODULE_ALIAS("w1-family-" __stringify(W1_THERM_DS1825));
  44 MODULE_ALIAS("w1-family-" __stringify(W1_THERM_DS28EA00));
  45
  46 /* Allow the strong pullup to be disabled, but default to enabled.
  47  * If it was disabled a parasite powered device might not get the require
  48  * current to do a temperature conversion.  If it is enabled parasite powered
  49  * devices have a better chance of getting the current required.
  50  * In case the parasite power-detection is not working (seems to be the case
  51  * for some DS18S20) the strong pullup can also be forced, regardless of the
  52  * power state of the devices.
  53  *
  54  * Summary of options:
  55  * - strong_pullup = 0  Disable strong pullup completely
  56  * - strong_pullup = 1  Enable automatic strong pullup detection
  57  * - strong_pullup = 2  Force strong pullup
  58  */
  59 static int w1_strong_pullup = 1;
  60 module_param_named(strong_pullup, w1_strong_pullup, int, 0);
  61
  62 struct w1_therm_family_data {
  63         uint8_t rom[9];
  64         atomic_t refcnt;
  65 };
  66
  67 /* return the address of the refcnt in the family data */
  68 #define THERM_REFCNT(family_data) \
  69         (&((struct w1_therm_family_data*)family_data)->refcnt)
  70
  71 static int w1_therm_add_slave(struct w1_slave *sl)
  72 {
  73         sl->family_data = kzalloc(sizeof(struct w1_therm_family_data),
  74                 GFP_KERNEL);
  75         if (!sl->family_data)
  76                 return -ENOMEM;
  77         atomic_set(THERM_REFCNT(sl->family_data), 1);
  78         return 0;
  79 }
  80
  81 static void w1_therm_remove_slave(struct w1_slave *sl)
  82 {
  83         int refcnt = atomic_sub_return(1, THERM_REFCNT(sl->family_data));
  84         while(refcnt) {
  85                 msleep(1000);
  86                 refcnt = atomic_read(THERM_REFCNT(sl->family_data));
  87         }
  88         kfree(sl->family_data);
  89         sl->family_data = NULL;
  90 }
  91
  92 static ssize_t w1_slave_show(struct device *device,
  93         struct device_attribute *attr, char *buf);
  94
  95 static DEVICE_ATTR_RO(w1_slave);
  96
  97 static struct attribute *w1_therm_attrs[] = {
  98         &dev_attr_w1_slave.attr,
  99         NULL,
 100 };
 101 ATTRIBUTE_GROUPS(w1_therm);
 102
 103 static struct w1_family_ops w1_therm_fops = {
 104         .add_slave      = w1_therm_add_slave,
 105         .remove_slave   = w1_therm_remove_slave,
 106         .groups         = w1_therm_groups,
 107 };
 108
 109 static struct w1_family w1_therm_family_DS18S20 = {
 110         .fid = W1_THERM_DS18S20,
 111         .fops = &w1_therm_fops,
 112 };
 113
 114 static struct w1_family w1_therm_family_DS18B20 = {
 115         .fid = W1_THERM_DS18B20,
 116         .fops = &w1_therm_fops,
 117 };
 118
 119 static struct w1_family w1_therm_family_DS1822 = {
 120         .fid = W1_THERM_DS1822,
 121         .fops = &w1_therm_fops,
 122 };
 123
 124 static struct w1_family w1_therm_family_DS28EA00 = {
 125         .fid = W1_THERM_DS28EA00,
 126         .fops = &w1_therm_fops,
 127 };
 128
 129 static struct w1_family w1_therm_family_DS1825 = {
 130         .fid = W1_THERM_DS1825,
 131         .fops = &w1_therm_fops,
 132 };
 133
 134 struct w1_therm_family_converter
 135 {
 136         u8                      broken;
 137         u16                     reserved;
 138         struct w1_family        *f;
 139         int                     (*convert)(u8 rom[9]);
 140 };
 141
 142 /* The return value is millidegrees Centigrade. */
 143 static inline int w1_DS18B20_convert_temp(u8 rom[9]);
 144 static inline int w1_DS18S20_convert_temp(u8 rom[9]);
 145
 146 static struct w1_therm_family_converter w1_therm_families[] = {
 147         {
 148                 .f              = &w1_therm_family_DS18S20,
 149                 .convert        = w1_DS18S20_convert_temp
 150         },
 151         {
 152                 .f              = &w1_therm_family_DS1822,
 153                 .convert        = w1_DS18B20_convert_temp
 154         },
 155         {
 156                 .f              = &w1_therm_family_DS18B20,
 157                 .convert        = w1_DS18B20_convert_temp
 158         },
 159         {
 160                 .f              = &w1_therm_family_DS28EA00,
 161                 .convert        = w1_DS18B20_convert_temp
 162         },
 163         {
 164                 .f              = &w1_therm_family_DS1825,
 165                 .convert        = w1_DS18B20_convert_temp
 166         }
 167 };
 168
 169 static inline int w1_DS18B20_convert_temp(u8 rom[9])
 170 {
 171         s16 t = le16_to_cpup((__le16 *)rom);
 172         return t*1000/16;
 173 }
 174
 175 static inline int w1_DS18S20_convert_temp(u8 rom[9])
 176 {
 177         int t, h;
 178
 179         if (!rom[7])
 180                 return 0;
 181
 182         if (rom[1] == 0)
 183                 t = ((s32)rom[0] >> 1)*1000;
 184         else
 185                 t = 1000*(-1*(s32)(0x100-rom[0]) >> 1);
 186
 187         t -= 250;
 188         h = 1000*((s32)rom[7] - (s32)rom[6]);
 189         h /= (s32)rom[7];
 190         t += h;
 191
 192         return t;
 193 }
 194
 195 static inline int w1_convert_temp(u8 rom[9], u8 fid)
 196 {
 197         int i;
 198
 199         for (i = 0; i < ARRAY_SIZE(w1_therm_families); ++i)
 200                 if (w1_therm_families[i].f->fid == fid)
 201                         return w1_therm_families[i].convert(rom);
 202
 203         return 0;
 204 }
 205
 206
 207 static ssize_t w1_slave_show(struct device *device,
 208         struct device_attribute *attr, char *buf)
 209 {
 210         struct w1_slave *sl = dev_to_w1_slave(device);
 211         struct w1_master *dev = sl->master;
 212         u8 rom[9], crc, verdict, external_power;
 213         int i, ret, max_trying = 10;
 214         ssize_t c = PAGE_SIZE;
 215         u8 *family_data = sl->family_data;
 216
 217         ret = mutex_lock_interruptible(&dev->bus_mutex);
 218         if (ret != 0)
 219                 goto post_unlock;
 220
 221         if(!sl->family_data)
 222         {
 223                 ret = -ENODEV;
 224                 goto pre_unlock;
 225         }
 226
 227         /* prevent the slave from going away in sleep */
 228         atomic_inc(THERM_REFCNT(family_data));
 229         memset(rom, 0, sizeof(rom));
 230
 231         while (max_trying--) {
 232
 233                 verdict = 0;
 234                 crc = 0;
 235
 236                 if (!w1_reset_select_slave(sl)) {
 237                         int count = 0;
 238                         unsigned int tm = 750;
 239                         unsigned long sleep_rem;
 240
 241                         w1_write_8(dev, W1_READ_PSUPPLY);
 242                         external_power = w1_read_8(dev);
 243
 244                         if (w1_reset_select_slave(sl))
 245                                 continue;
 246
 247                         /* 750ms strong pullup (or delay) after the convert */
 248                         if (w1_strong_pullup == 2 ||
 249                                         (!external_power && w1_strong_pullup))
 250                                 w1_next_pullup(dev, tm);
 251
 252                         w1_write_8(dev, W1_CONVERT_TEMP);
 253
 254                         if (external_power) {
 255                                 mutex_unlock(&dev->bus_mutex);
 256
 257                                 sleep_rem = msleep_interruptible(tm);
 258                                 if (sleep_rem != 0) {
 259                                         ret = -EINTR;
 260                                         goto post_unlock;
 261                                 }
 262
 263                                 ret = mutex_lock_interruptible(&dev->bus_mutex);
 264                                 if (ret != 0)
 265                                         goto post_unlock;
 266                         } else if (!w1_strong_pullup) {
 267                                 sleep_rem = msleep_interruptible(tm);
 268                                 if (sleep_rem != 0) {
 269                                         ret = -EINTR;
 270                                         goto pre_unlock;
 271                                 }
 272                         }
 273
 274                         if (!w1_reset_select_slave(sl)) {
 275
 276                                 w1_write_8(dev, W1_READ_SCRATCHPAD);
 277                                 if ((count = w1_read_block(dev, rom, 9)) != 9) {
 278                                         dev_warn(device, "w1_read_block() "
 279                                                 "returned %u instead of 9.\n",
 280                                                 count);
 281                                 }
 282
 283                                 crc = w1_calc_crc8(rom, 8);
 284
 285                                 if (rom[8] == crc)
 286                                         verdict = 1;
 287                         }
 288                 }
 289
 290                 if (verdict)
 291                         break;
 292         }
 293
 294         for (i = 0; i < 9; ++i)
 295                 c -= snprintf(buf + PAGE_SIZE - c, c, "%02x ", rom[i]);
 296         c -= snprintf(buf + PAGE_SIZE - c, c, ": crc=%02x %s\n",
 297                            crc, (verdict) ? "YES" : "NO");
 298         if (verdict)
 299                 memcpy(family_data, rom, sizeof(rom));
 300         else
 301                 dev_warn(device, "Read failed CRC check\n");
 302
 303         for (i = 0; i < 9; ++i)
 304                 c -= snprintf(buf + PAGE_SIZE - c, c, "%02x ",
 305                               ((u8 *)family_data)[i]);
 306
 307         c -= snprintf(buf + PAGE_SIZE - c, c, "t=%d\n",
 308                 w1_convert_temp(rom, sl->family->fid));
 309         ret = PAGE_SIZE - c;
 310
 311 pre_unlock:
 312         mutex_unlock(&dev->bus_mutex);
 313
 314 post_unlock:
 315         atomic_dec(THERM_REFCNT(family_data));
 316         return ret;
 317 }
 318
 319 static int __init w1_therm_init(void)
 320 {
 321         int err, i;
 322
 323         for (i = 0; i < ARRAY_SIZE(w1_therm_families); ++i) {
 324                 err = w1_register_family(w1_therm_families[i].f);
 325                 if (err)
 326                         w1_therm_families[i].broken = 1;
 327         }
 328
 329         return 0;
 330 }
 331
 332 static void __exit w1_therm_fini(void)
 333 {
 334         int i;
 335
 336         for (i = 0; i < ARRAY_SIZE(w1_therm_families); ++i)
 337                 if (!w1_therm_families[i].broken)
 338                         w1_unregister_family(w1_therm_families[i].f);
 339 }
 340
 341 module_init(w1_therm_init);
 342 module_exit(w1_therm_fini);