1 /* 2 * w1_therm.c 3 * 4 * Copyright (c) 2004 Evgeniy Polyakov <johnpol@2ka.mipt.ru> 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 <johnpol@2ka.mipt.ru>"); 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 */ 45 static int w1_strong_pullup = 1; 46 module_param_named(strong_pullup, w1_strong_pullup, int, 0); 47 48 static u8 bad_roms[][9] = { 49 {0xaa, 0x00, 0x4b, 0x46, 0xff, 0xff, 0x0c, 0x10, 0x87}, 50 {} 51 }; 52 53 static ssize_t w1_therm_read(struct device *device, 54 struct device_attribute *attr, char *buf); 55 56 static struct device_attribute w1_therm_attr = 57 __ATTR(w1_slave, S_IRUGO, w1_therm_read, NULL); 58 59 static int w1_therm_add_slave(struct w1_slave *sl) 60 { 61 return device_create_file(&sl->dev, &w1_therm_attr); 62 } 63 64 static void w1_therm_remove_slave(struct w1_slave *sl) 65 { 66 device_remove_file(&sl->dev, &w1_therm_attr); 67 } 68 69 static struct w1_family_ops w1_therm_fops = { 70 .add_slave = w1_therm_add_slave, 71 .remove_slave = w1_therm_remove_slave, 72 }; 73 74 static struct w1_family w1_therm_family_DS18S20 = { 75 .fid = W1_THERM_DS18S20, 76 .fops = &w1_therm_fops, 77 }; 78 79 static struct w1_family w1_therm_family_DS18B20 = { 80 .fid = W1_THERM_DS18B20, 81 .fops = &w1_therm_fops, 82 }; 83 84 static struct w1_family w1_therm_family_DS1822 = { 85 .fid = W1_THERM_DS1822, 86 .fops = &w1_therm_fops, 87 }; 88 89 struct w1_therm_family_converter 90 { 91 u8 broken; 92 u16 reserved; 93 struct w1_family *f; 94 int (*convert)(u8 rom[9]); 95 }; 96 97 /* The return value is millidegrees Centigrade. */ 98 static inline int w1_DS18B20_convert_temp(u8 rom[9]); 99 static inline int w1_DS18S20_convert_temp(u8 rom[9]); 100 101 static struct w1_therm_family_converter w1_therm_families[] = { 102 { 103 .f = &w1_therm_family_DS18S20, 104 .convert = w1_DS18S20_convert_temp 105 }, 106 { 107 .f = &w1_therm_family_DS1822, 108 .convert = w1_DS18B20_convert_temp 109 }, 110 { 111 .f = &w1_therm_family_DS18B20, 112 .convert = w1_DS18B20_convert_temp 113 }, 114 }; 115 116 static inline int w1_DS18B20_convert_temp(u8 rom[9]) 117 { 118 int t = ((s16)rom[1] << 8) | rom[0]; 119 t = t*1000/16; 120 return t; 121 } 122 123 static inline int w1_DS18S20_convert_temp(u8 rom[9]) 124 { 125 int t, h; 126 127 if (!rom[7]) 128 return 0; 129 130 if (rom[1] == 0) 131 t = ((s32)rom[0] >> 1)*1000; 132 else 133 t = 1000*(-1*(s32)(0x100-rom[0]) >> 1); 134 135 t -= 250; 136 h = 1000*((s32)rom[7] - (s32)rom[6]); 137 h /= (s32)rom[7]; 138 t += h; 139 140 return t; 141 } 142 143 static inline int w1_convert_temp(u8 rom[9], u8 fid) 144 { 145 int i; 146 147 for (i = 0; i < ARRAY_SIZE(w1_therm_families); ++i) 148 if (w1_therm_families[i].f->fid == fid) 149 return w1_therm_families[i].convert(rom); 150 151 return 0; 152 } 153 154 static int w1_therm_check_rom(u8 rom[9]) 155 { 156 int i; 157 158 for (i=0; i<sizeof(bad_roms)/9; ++i) 159 if (!memcmp(bad_roms[i], rom, 9)) 160 return 1; 161 162 return 0; 163 } 164 165 static ssize_t w1_therm_read(struct device *device, 166 struct device_attribute *attr, char *buf) 167 { 168 struct w1_slave *sl = dev_to_w1_slave(device); 169 struct w1_master *dev = sl->master; 170 u8 rom[9], crc, verdict; 171 int i, max_trying = 10; 172 ssize_t c = PAGE_SIZE; 173 174 mutex_lock(&dev->mutex); 175 176 memset(rom, 0, sizeof(rom)); 177 178 verdict = 0; 179 crc = 0; 180 181 while (max_trying--) { 182 if (!w1_reset_select_slave(sl)) { 183 int count = 0; 184 unsigned int tm = 750; 185 186 /* 750ms strong pullup (or delay) after the convert */ 187 if (w1_strong_pullup) 188 w1_next_pullup(dev, tm); 189 w1_write_8(dev, W1_CONVERT_TEMP); 190 if (!w1_strong_pullup) 191 msleep(tm); 192 193 if (!w1_reset_select_slave(sl)) { 194 195 w1_write_8(dev, W1_READ_SCRATCHPAD); 196 if ((count = w1_read_block(dev, rom, 9)) != 9) { 197 dev_warn(device, "w1_read_block() " 198 "returned %u instead of 9.\n", 199 count); 200 } 201 202 crc = w1_calc_crc8(rom, 8); 203 204 if (rom[8] == crc) 205 verdict = 1; 206 } 207 } 208 209 if (!w1_therm_check_rom(rom)) 210 break; 211 } 212 213 for (i = 0; i < 9; ++i) 214 c -= snprintf(buf + PAGE_SIZE - c, c, "%02x ", rom[i]); 215 c -= snprintf(buf + PAGE_SIZE - c, c, ": crc=%02x %s\n", 216 crc, (verdict) ? "YES" : "NO"); 217 if (verdict) 218 memcpy(sl->rom, rom, sizeof(sl->rom)); 219 else 220 dev_warn(device, "18S20 doesn't respond to CONVERT_TEMP.\n"); 221 222 for (i = 0; i < 9; ++i) 223 c -= snprintf(buf + PAGE_SIZE - c, c, "%02x ", sl->rom[i]); 224 225 c -= snprintf(buf + PAGE_SIZE - c, c, "t=%d\n", 226 w1_convert_temp(rom, sl->family->fid)); 227 mutex_unlock(&dev->mutex); 228 229 return PAGE_SIZE - c; 230 } 231 232 static int __init w1_therm_init(void) 233 { 234 int err, i; 235 236 for (i = 0; i < ARRAY_SIZE(w1_therm_families); ++i) { 237 err = w1_register_family(w1_therm_families[i].f); 238 if (err) 239 w1_therm_families[i].broken = 1; 240 } 241 242 return 0; 243 } 244 245 static void __exit w1_therm_fini(void) 246 { 247 int i; 248 249 for (i = 0; i < ARRAY_SIZE(w1_therm_families); ++i) 250 if (!w1_therm_families[i].broken) 251 w1_unregister_family(w1_therm_families[i].f); 252 } 253 254 module_init(w1_therm_init); 255 module_exit(w1_therm_fini); 256