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 40 /* Allow the strong pullup to be disabled, but default to enabled. 41 * If it was disabled a parasite powered device might not get the require 42 * current to do a temperature conversion. If it is enabled parasite powered 43 * devices have a better chance of getting the current required. 44 * In case the parasite power-detection is not working (seems to be the case 45 * for some DS18S20) the strong pullup can also be forced, regardless of the 46 * power state of the devices. 47 * 48 * Summary of options: 49 * - strong_pullup = 0 Disable strong pullup completely 50 * - strong_pullup = 1 Enable automatic strong pullup detection 51 * - strong_pullup = 2 Force strong pullup 52 */ 53 static int w1_strong_pullup = 1; 54 module_param_named(strong_pullup, w1_strong_pullup, int, 0); 55 56 57 static ssize_t w1_therm_read(struct device *device, 58 struct device_attribute *attr, char *buf); 59 60 static struct device_attribute w1_therm_attr = 61 __ATTR(w1_slave, S_IRUGO, w1_therm_read, NULL); 62 63 static int w1_therm_add_slave(struct w1_slave *sl) 64 { 65 return device_create_file(&sl->dev, &w1_therm_attr); 66 } 67 68 static void w1_therm_remove_slave(struct w1_slave *sl) 69 { 70 device_remove_file(&sl->dev, &w1_therm_attr); 71 } 72 73 static struct w1_family_ops w1_therm_fops = { 74 .add_slave = w1_therm_add_slave, 75 .remove_slave = w1_therm_remove_slave, 76 }; 77 78 static struct w1_family w1_therm_family_DS18S20 = { 79 .fid = W1_THERM_DS18S20, 80 .fops = &w1_therm_fops, 81 }; 82 83 static struct w1_family w1_therm_family_DS18B20 = { 84 .fid = W1_THERM_DS18B20, 85 .fops = &w1_therm_fops, 86 }; 87 88 static struct w1_family w1_therm_family_DS1822 = { 89 .fid = W1_THERM_DS1822, 90 .fops = &w1_therm_fops, 91 }; 92 93 static struct w1_family w1_therm_family_DS28EA00 = { 94 .fid = W1_THERM_DS28EA00, 95 .fops = &w1_therm_fops, 96 }; 97 98 static struct w1_family w1_therm_family_DS1825 = { 99 .fid = W1_THERM_DS1825, 100 .fops = &w1_therm_fops, 101 }; 102 103 struct w1_therm_family_converter 104 { 105 u8 broken; 106 u16 reserved; 107 struct w1_family *f; 108 int (*convert)(u8 rom[9]); 109 }; 110 111 /* The return value is millidegrees Centigrade. */ 112 static inline int w1_DS18B20_convert_temp(u8 rom[9]); 113 static inline int w1_DS18S20_convert_temp(u8 rom[9]); 114 115 static struct w1_therm_family_converter w1_therm_families[] = { 116 { 117 .f = &w1_therm_family_DS18S20, 118 .convert = w1_DS18S20_convert_temp 119 }, 120 { 121 .f = &w1_therm_family_DS1822, 122 .convert = w1_DS18B20_convert_temp 123 }, 124 { 125 .f = &w1_therm_family_DS18B20, 126 .convert = w1_DS18B20_convert_temp 127 }, 128 { 129 .f = &w1_therm_family_DS28EA00, 130 .convert = w1_DS18B20_convert_temp 131 }, 132 { 133 .f = &w1_therm_family_DS1825, 134 .convert = w1_DS18B20_convert_temp 135 } 136 }; 137 138 static inline int w1_DS18B20_convert_temp(u8 rom[9]) 139 { 140 s16 t = le16_to_cpup((__le16 *)rom); 141 return t*1000/16; 142 } 143 144 static inline int w1_DS18S20_convert_temp(u8 rom[9]) 145 { 146 int t, h; 147 148 if (!rom[7]) 149 return 0; 150 151 if (rom[1] == 0) 152 t = ((s32)rom[0] >> 1)*1000; 153 else 154 t = 1000*(-1*(s32)(0x100-rom[0]) >> 1); 155 156 t -= 250; 157 h = 1000*((s32)rom[7] - (s32)rom[6]); 158 h /= (s32)rom[7]; 159 t += h; 160 161 return t; 162 } 163 164 static inline int w1_convert_temp(u8 rom[9], u8 fid) 165 { 166 int i; 167 168 for (i = 0; i < ARRAY_SIZE(w1_therm_families); ++i) 169 if (w1_therm_families[i].f->fid == fid) 170 return w1_therm_families[i].convert(rom); 171 172 return 0; 173 } 174 175 176 static ssize_t w1_therm_read(struct device *device, 177 struct device_attribute *attr, char *buf) 178 { 179 struct w1_slave *sl = dev_to_w1_slave(device); 180 struct w1_master *dev = sl->master; 181 u8 rom[9], crc, verdict, external_power; 182 int i, max_trying = 10; 183 ssize_t c = PAGE_SIZE; 184 185 i = mutex_lock_interruptible(&dev->bus_mutex); 186 if (i != 0) 187 return i; 188 189 memset(rom, 0, sizeof(rom)); 190 191 while (max_trying--) { 192 193 verdict = 0; 194 crc = 0; 195 196 if (!w1_reset_select_slave(sl)) { 197 int count = 0; 198 unsigned int tm = 750; 199 unsigned long sleep_rem; 200 201 w1_write_8(dev, W1_READ_PSUPPLY); 202 external_power = w1_read_8(dev); 203 204 if (w1_reset_select_slave(sl)) 205 continue; 206 207 /* 750ms strong pullup (or delay) after the convert */ 208 if (w1_strong_pullup == 2 || 209 (!external_power && w1_strong_pullup)) 210 w1_next_pullup(dev, tm); 211 212 w1_write_8(dev, W1_CONVERT_TEMP); 213 214 if (external_power) { 215 mutex_unlock(&dev->bus_mutex); 216 217 sleep_rem = msleep_interruptible(tm); 218 if (sleep_rem != 0) 219 return -EINTR; 220 221 i = mutex_lock_interruptible(&dev->bus_mutex); 222 if (i != 0) 223 return i; 224 } else if (!w1_strong_pullup) { 225 sleep_rem = msleep_interruptible(tm); 226 if (sleep_rem != 0) { 227 mutex_unlock(&dev->bus_mutex); 228 return -EINTR; 229 } 230 } 231 232 if (!w1_reset_select_slave(sl)) { 233 234 w1_write_8(dev, W1_READ_SCRATCHPAD); 235 if ((count = w1_read_block(dev, rom, 9)) != 9) { 236 dev_warn(device, "w1_read_block() " 237 "returned %u instead of 9.\n", 238 count); 239 } 240 241 crc = w1_calc_crc8(rom, 8); 242 243 if (rom[8] == crc) 244 verdict = 1; 245 } 246 } 247 248 if (verdict) 249 break; 250 } 251 252 for (i = 0; i < 9; ++i) 253 c -= snprintf(buf + PAGE_SIZE - c, c, "%02x ", rom[i]); 254 c -= snprintf(buf + PAGE_SIZE - c, c, ": crc=%02x %s\n", 255 crc, (verdict) ? "YES" : "NO"); 256 if (verdict) 257 memcpy(sl->rom, rom, sizeof(sl->rom)); 258 else 259 dev_warn(device, "Read failed CRC check\n"); 260 261 for (i = 0; i < 9; ++i) 262 c -= snprintf(buf + PAGE_SIZE - c, c, "%02x ", sl->rom[i]); 263 264 c -= snprintf(buf + PAGE_SIZE - c, c, "t=%d\n", 265 w1_convert_temp(rom, sl->family->fid)); 266 mutex_unlock(&dev->bus_mutex); 267 268 return PAGE_SIZE - c; 269 } 270 271 static int __init w1_therm_init(void) 272 { 273 int err, i; 274 275 for (i = 0; i < ARRAY_SIZE(w1_therm_families); ++i) { 276 err = w1_register_family(w1_therm_families[i].f); 277 if (err) 278 w1_therm_families[i].broken = 1; 279 } 280 281 return 0; 282 } 283 284 static void __exit w1_therm_fini(void) 285 { 286 int i; 287 288 for (i = 0; i < ARRAY_SIZE(w1_therm_families); ++i) 289 if (!w1_therm_families[i].broken) 290 w1_unregister_family(w1_therm_families[i].f); 291 } 292 293 module_init(w1_therm_init); 294 module_exit(w1_therm_fini); 295