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); 294