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_therm_read(struct device *device, 63 struct device_attribute *attr, char *buf); 64 65 static struct device_attribute w1_therm_attr = 66 __ATTR(w1_slave, S_IRUGO, w1_therm_read, NULL); 67 68 static int w1_therm_add_slave(struct w1_slave *sl) 69 { 70 return device_create_file(&sl->dev, &w1_therm_attr); 71 } 72 73 static void w1_therm_remove_slave(struct w1_slave *sl) 74 { 75 device_remove_file(&sl->dev, &w1_therm_attr); 76 } 77 78 static struct w1_family_ops w1_therm_fops = { 79 .add_slave = w1_therm_add_slave, 80 .remove_slave = w1_therm_remove_slave, 81 }; 82 83 static struct w1_family w1_therm_family_DS18S20 = { 84 .fid = W1_THERM_DS18S20, 85 .fops = &w1_therm_fops, 86 }; 87 88 static struct w1_family w1_therm_family_DS18B20 = { 89 .fid = W1_THERM_DS18B20, 90 .fops = &w1_therm_fops, 91 }; 92 93 static struct w1_family w1_therm_family_DS1822 = { 94 .fid = W1_THERM_DS1822, 95 .fops = &w1_therm_fops, 96 }; 97 98 static struct w1_family w1_therm_family_DS28EA00 = { 99 .fid = W1_THERM_DS28EA00, 100 .fops = &w1_therm_fops, 101 }; 102 103 static struct w1_family w1_therm_family_DS1825 = { 104 .fid = W1_THERM_DS1825, 105 .fops = &w1_therm_fops, 106 }; 107 108 struct w1_therm_family_converter 109 { 110 u8 broken; 111 u16 reserved; 112 struct w1_family *f; 113 int (*convert)(u8 rom[9]); 114 }; 115 116 /* The return value is millidegrees Centigrade. */ 117 static inline int w1_DS18B20_convert_temp(u8 rom[9]); 118 static inline int w1_DS18S20_convert_temp(u8 rom[9]); 119 120 static struct w1_therm_family_converter w1_therm_families[] = { 121 { 122 .f = &w1_therm_family_DS18S20, 123 .convert = w1_DS18S20_convert_temp 124 }, 125 { 126 .f = &w1_therm_family_DS1822, 127 .convert = w1_DS18B20_convert_temp 128 }, 129 { 130 .f = &w1_therm_family_DS18B20, 131 .convert = w1_DS18B20_convert_temp 132 }, 133 { 134 .f = &w1_therm_family_DS28EA00, 135 .convert = w1_DS18B20_convert_temp 136 }, 137 { 138 .f = &w1_therm_family_DS1825, 139 .convert = w1_DS18B20_convert_temp 140 } 141 }; 142 143 static inline int w1_DS18B20_convert_temp(u8 rom[9]) 144 { 145 s16 t = le16_to_cpup((__le16 *)rom); 146 return t*1000/16; 147 } 148 149 static inline int w1_DS18S20_convert_temp(u8 rom[9]) 150 { 151 int t, h; 152 153 if (!rom[7]) 154 return 0; 155 156 if (rom[1] == 0) 157 t = ((s32)rom[0] >> 1)*1000; 158 else 159 t = 1000*(-1*(s32)(0x100-rom[0]) >> 1); 160 161 t -= 250; 162 h = 1000*((s32)rom[7] - (s32)rom[6]); 163 h /= (s32)rom[7]; 164 t += h; 165 166 return t; 167 } 168 169 static inline int w1_convert_temp(u8 rom[9], u8 fid) 170 { 171 int i; 172 173 for (i = 0; i < ARRAY_SIZE(w1_therm_families); ++i) 174 if (w1_therm_families[i].f->fid == fid) 175 return w1_therm_families[i].convert(rom); 176 177 return 0; 178 } 179 180 181 static ssize_t w1_therm_read(struct device *device, 182 struct device_attribute *attr, char *buf) 183 { 184 struct w1_slave *sl = dev_to_w1_slave(device); 185 struct w1_master *dev = sl->master; 186 u8 rom[9], crc, verdict, external_power; 187 int i, max_trying = 10; 188 ssize_t c = PAGE_SIZE; 189 190 i = mutex_lock_interruptible(&dev->bus_mutex); 191 if (i != 0) 192 return i; 193 194 memset(rom, 0, sizeof(rom)); 195 196 while (max_trying--) { 197 198 verdict = 0; 199 crc = 0; 200 201 if (!w1_reset_select_slave(sl)) { 202 int count = 0; 203 unsigned int tm = 750; 204 unsigned long sleep_rem; 205 206 w1_write_8(dev, W1_READ_PSUPPLY); 207 external_power = w1_read_8(dev); 208 209 if (w1_reset_select_slave(sl)) 210 continue; 211 212 /* 750ms strong pullup (or delay) after the convert */ 213 if (w1_strong_pullup == 2 || 214 (!external_power && w1_strong_pullup)) 215 w1_next_pullup(dev, tm); 216 217 w1_write_8(dev, W1_CONVERT_TEMP); 218 219 if (external_power) { 220 mutex_unlock(&dev->bus_mutex); 221 222 sleep_rem = msleep_interruptible(tm); 223 if (sleep_rem != 0) 224 return -EINTR; 225 226 i = mutex_lock_interruptible(&dev->bus_mutex); 227 if (i != 0) 228 return i; 229 } else if (!w1_strong_pullup) { 230 sleep_rem = msleep_interruptible(tm); 231 if (sleep_rem != 0) { 232 mutex_unlock(&dev->bus_mutex); 233 return -EINTR; 234 } 235 } 236 237 if (!w1_reset_select_slave(sl)) { 238 239 w1_write_8(dev, W1_READ_SCRATCHPAD); 240 if ((count = w1_read_block(dev, rom, 9)) != 9) { 241 dev_warn(device, "w1_read_block() " 242 "returned %u instead of 9.\n", 243 count); 244 } 245 246 crc = w1_calc_crc8(rom, 8); 247 248 if (rom[8] == crc) 249 verdict = 1; 250 } 251 } 252 253 if (verdict) 254 break; 255 } 256 257 for (i = 0; i < 9; ++i) 258 c -= snprintf(buf + PAGE_SIZE - c, c, "%02x ", rom[i]); 259 c -= snprintf(buf + PAGE_SIZE - c, c, ": crc=%02x %s\n", 260 crc, (verdict) ? "YES" : "NO"); 261 if (verdict) 262 memcpy(sl->rom, rom, sizeof(sl->rom)); 263 else 264 dev_warn(device, "Read failed CRC check\n"); 265 266 for (i = 0; i < 9; ++i) 267 c -= snprintf(buf + PAGE_SIZE - c, c, "%02x ", sl->rom[i]); 268 269 c -= snprintf(buf + PAGE_SIZE - c, c, "t=%d\n", 270 w1_convert_temp(rom, sl->family->fid)); 271 mutex_unlock(&dev->bus_mutex); 272 273 return PAGE_SIZE - c; 274 } 275 276 static int __init w1_therm_init(void) 277 { 278 int err, i; 279 280 for (i = 0; i < ARRAY_SIZE(w1_therm_families); ++i) { 281 err = w1_register_family(w1_therm_families[i].f); 282 if (err) 283 w1_therm_families[i].broken = 1; 284 } 285 286 return 0; 287 } 288 289 static void __exit w1_therm_fini(void) 290 { 291 int i; 292 293 for (i = 0; i < ARRAY_SIZE(w1_therm_families); ++i) 294 if (!w1_therm_families[i].broken) 295 w1_unregister_family(w1_therm_families[i].f); 296 } 297 298 module_init(w1_therm_init); 299 module_exit(w1_therm_fini); 300