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 static int w1_therm_add_slave(struct w1_slave *sl) 63 { 64 sl->family_data = kzalloc(9, GFP_KERNEL); 65 if (!sl->family_data) 66 return -ENOMEM; 67 return 0; 68 } 69 70 static void w1_therm_remove_slave(struct w1_slave *sl) 71 { 72 kfree(sl->family_data); 73 sl->family_data = NULL; 74 } 75 76 static ssize_t w1_slave_show(struct device *device, 77 struct device_attribute *attr, char *buf); 78 79 static DEVICE_ATTR_RO(w1_slave); 80 81 static struct attribute *w1_therm_attrs[] = { 82 &dev_attr_w1_slave.attr, 83 NULL, 84 }; 85 ATTRIBUTE_GROUPS(w1_therm); 86 87 static struct w1_family_ops w1_therm_fops = { 88 .add_slave = w1_therm_add_slave, 89 .remove_slave = w1_therm_remove_slave, 90 .groups = w1_therm_groups, 91 }; 92 93 static struct w1_family w1_therm_family_DS18S20 = { 94 .fid = W1_THERM_DS18S20, 95 .fops = &w1_therm_fops, 96 }; 97 98 static struct w1_family w1_therm_family_DS18B20 = { 99 .fid = W1_THERM_DS18B20, 100 .fops = &w1_therm_fops, 101 }; 102 103 static struct w1_family w1_therm_family_DS1822 = { 104 .fid = W1_THERM_DS1822, 105 .fops = &w1_therm_fops, 106 }; 107 108 static struct w1_family w1_therm_family_DS28EA00 = { 109 .fid = W1_THERM_DS28EA00, 110 .fops = &w1_therm_fops, 111 }; 112 113 static struct w1_family w1_therm_family_DS1825 = { 114 .fid = W1_THERM_DS1825, 115 .fops = &w1_therm_fops, 116 }; 117 118 struct w1_therm_family_converter 119 { 120 u8 broken; 121 u16 reserved; 122 struct w1_family *f; 123 int (*convert)(u8 rom[9]); 124 }; 125 126 /* The return value is millidegrees Centigrade. */ 127 static inline int w1_DS18B20_convert_temp(u8 rom[9]); 128 static inline int w1_DS18S20_convert_temp(u8 rom[9]); 129 130 static struct w1_therm_family_converter w1_therm_families[] = { 131 { 132 .f = &w1_therm_family_DS18S20, 133 .convert = w1_DS18S20_convert_temp 134 }, 135 { 136 .f = &w1_therm_family_DS1822, 137 .convert = w1_DS18B20_convert_temp 138 }, 139 { 140 .f = &w1_therm_family_DS18B20, 141 .convert = w1_DS18B20_convert_temp 142 }, 143 { 144 .f = &w1_therm_family_DS28EA00, 145 .convert = w1_DS18B20_convert_temp 146 }, 147 { 148 .f = &w1_therm_family_DS1825, 149 .convert = w1_DS18B20_convert_temp 150 } 151 }; 152 153 static inline int w1_DS18B20_convert_temp(u8 rom[9]) 154 { 155 s16 t = le16_to_cpup((__le16 *)rom); 156 return t*1000/16; 157 } 158 159 static inline int w1_DS18S20_convert_temp(u8 rom[9]) 160 { 161 int t, h; 162 163 if (!rom[7]) 164 return 0; 165 166 if (rom[1] == 0) 167 t = ((s32)rom[0] >> 1)*1000; 168 else 169 t = 1000*(-1*(s32)(0x100-rom[0]) >> 1); 170 171 t -= 250; 172 h = 1000*((s32)rom[7] - (s32)rom[6]); 173 h /= (s32)rom[7]; 174 t += h; 175 176 return t; 177 } 178 179 static inline int w1_convert_temp(u8 rom[9], u8 fid) 180 { 181 int i; 182 183 for (i = 0; i < ARRAY_SIZE(w1_therm_families); ++i) 184 if (w1_therm_families[i].f->fid == fid) 185 return w1_therm_families[i].convert(rom); 186 187 return 0; 188 } 189 190 191 static ssize_t w1_slave_show(struct device *device, 192 struct device_attribute *attr, char *buf) 193 { 194 struct w1_slave *sl = dev_to_w1_slave(device); 195 struct w1_master *dev = sl->master; 196 u8 rom[9], crc, verdict, external_power; 197 int i, max_trying = 10; 198 ssize_t c = PAGE_SIZE; 199 200 i = mutex_lock_interruptible(&dev->bus_mutex); 201 if (i != 0) 202 return i; 203 204 memset(rom, 0, sizeof(rom)); 205 206 while (max_trying--) { 207 208 verdict = 0; 209 crc = 0; 210 211 if (!w1_reset_select_slave(sl)) { 212 int count = 0; 213 unsigned int tm = 750; 214 unsigned long sleep_rem; 215 216 w1_write_8(dev, W1_READ_PSUPPLY); 217 external_power = w1_read_8(dev); 218 219 if (w1_reset_select_slave(sl)) 220 continue; 221 222 /* 750ms strong pullup (or delay) after the convert */ 223 if (w1_strong_pullup == 2 || 224 (!external_power && w1_strong_pullup)) 225 w1_next_pullup(dev, tm); 226 227 w1_write_8(dev, W1_CONVERT_TEMP); 228 229 if (external_power) { 230 mutex_unlock(&dev->bus_mutex); 231 232 sleep_rem = msleep_interruptible(tm); 233 if (sleep_rem != 0) 234 return -EINTR; 235 236 i = mutex_lock_interruptible(&dev->bus_mutex); 237 if (i != 0) 238 return i; 239 } else if (!w1_strong_pullup) { 240 sleep_rem = msleep_interruptible(tm); 241 if (sleep_rem != 0) { 242 mutex_unlock(&dev->bus_mutex); 243 return -EINTR; 244 } 245 } 246 247 if (!w1_reset_select_slave(sl)) { 248 249 w1_write_8(dev, W1_READ_SCRATCHPAD); 250 if ((count = w1_read_block(dev, rom, 9)) != 9) { 251 dev_warn(device, "w1_read_block() " 252 "returned %u instead of 9.\n", 253 count); 254 } 255 256 crc = w1_calc_crc8(rom, 8); 257 258 if (rom[8] == crc) 259 verdict = 1; 260 } 261 } 262 263 if (verdict) 264 break; 265 } 266 267 for (i = 0; i < 9; ++i) 268 c -= snprintf(buf + PAGE_SIZE - c, c, "%02x ", rom[i]); 269 c -= snprintf(buf + PAGE_SIZE - c, c, ": crc=%02x %s\n", 270 crc, (verdict) ? "YES" : "NO"); 271 if (verdict) 272 memcpy(sl->family_data, rom, sizeof(rom)); 273 else 274 dev_warn(device, "Read failed CRC check\n"); 275 276 for (i = 0; i < 9; ++i) 277 c -= snprintf(buf + PAGE_SIZE - c, c, "%02x ", 278 ((u8 *)sl->family_data)[i]); 279 280 c -= snprintf(buf + PAGE_SIZE - c, c, "t=%d\n", 281 w1_convert_temp(rom, sl->family->fid)); 282 mutex_unlock(&dev->bus_mutex); 283 284 return PAGE_SIZE - c; 285 } 286 287 static int __init w1_therm_init(void) 288 { 289 int err, i; 290 291 for (i = 0; i < ARRAY_SIZE(w1_therm_families); ++i) { 292 err = w1_register_family(w1_therm_families[i].f); 293 if (err) 294 w1_therm_families[i].broken = 1; 295 } 296 297 return 0; 298 } 299 300 static void __exit w1_therm_fini(void) 301 { 302 int i; 303 304 for (i = 0; i < ARRAY_SIZE(w1_therm_families); ++i) 305 if (!w1_therm_families[i].broken) 306 w1_unregister_family(w1_therm_families[i].f); 307 } 308 309 module_init(w1_therm_init); 310 module_exit(w1_therm_fini); 311