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 36MODULE_LICENSE("GPL"); 37MODULE_AUTHOR("Evgeniy Polyakov <johnpol@2ka.mipt.ru>"); 38MODULE_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 */ 45static int w1_strong_pullup = 1; 46module_param_named(strong_pullup, w1_strong_pullup, int, 0); 47 48static u8 bad_roms[][9] = { 49 {0xaa, 0x00, 0x4b, 0x46, 0xff, 0xff, 0x0c, 0x10, 0x87}, 50 {} 51 }; 52 53static ssize_t w1_therm_read(struct device *device, 54 struct device_attribute *attr, char *buf); 55 56static struct device_attribute w1_therm_attr = 57 __ATTR(w1_slave, S_IRUGO, w1_therm_read, NULL); 58 59static int w1_therm_add_slave(struct w1_slave *sl) 60{ 61 return device_create_file(&sl->dev, &w1_therm_attr); 62} 63 64static void w1_therm_remove_slave(struct w1_slave *sl) 65{ 66 device_remove_file(&sl->dev, &w1_therm_attr); 67} 68 69static struct w1_family_ops w1_therm_fops = { 70 .add_slave = w1_therm_add_slave, 71 .remove_slave = w1_therm_remove_slave, 72}; 73 74static struct w1_family w1_therm_family_DS18S20 = { 75 .fid = W1_THERM_DS18S20, 76 .fops = &w1_therm_fops, 77}; 78 79static struct w1_family w1_therm_family_DS18B20 = { 80 .fid = W1_THERM_DS18B20, 81 .fops = &w1_therm_fops, 82}; 83 84static struct w1_family w1_therm_family_DS1822 = { 85 .fid = W1_THERM_DS1822, 86 .fops = &w1_therm_fops, 87}; 88 89struct 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. */ 98static inline int w1_DS18B20_convert_temp(u8 rom[9]); 99static inline int w1_DS18S20_convert_temp(u8 rom[9]); 100 101static 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 116static inline int w1_DS18B20_convert_temp(u8 rom[9]) 117{ 118 s16 t = le16_to_cpup((__le16 *)rom); 119 return t*1000/16; 120} 121 122static inline int w1_DS18S20_convert_temp(u8 rom[9]) 123{ 124 int t, h; 125 126 if (!rom[7]) 127 return 0; 128 129 if (rom[1] == 0) 130 t = ((s32)rom[0] >> 1)*1000; 131 else 132 t = 1000*(-1*(s32)(0x100-rom[0]) >> 1); 133 134 t -= 250; 135 h = 1000*((s32)rom[7] - (s32)rom[6]); 136 h /= (s32)rom[7]; 137 t += h; 138 139 return t; 140} 141 142static inline int w1_convert_temp(u8 rom[9], u8 fid) 143{ 144 int i; 145 146 for (i = 0; i < ARRAY_SIZE(w1_therm_families); ++i) 147 if (w1_therm_families[i].f->fid == fid) 148 return w1_therm_families[i].convert(rom); 149 150 return 0; 151} 152 153static int w1_therm_check_rom(u8 rom[9]) 154{ 155 int i; 156 157 for (i=0; i<sizeof(bad_roms)/9; ++i) 158 if (!memcmp(bad_roms[i], rom, 9)) 159 return 1; 160 161 return 0; 162} 163 164static ssize_t w1_therm_read(struct device *device, 165 struct device_attribute *attr, char *buf) 166{ 167 struct w1_slave *sl = dev_to_w1_slave(device); 168 struct w1_master *dev = sl->master; 169 u8 rom[9], crc, verdict; 170 int i, max_trying = 10; 171 ssize_t c = PAGE_SIZE; 172 173 mutex_lock(&dev->mutex); 174 175 memset(rom, 0, sizeof(rom)); 176 177 verdict = 0; 178 crc = 0; 179 180 while (max_trying--) { 181 if (!w1_reset_select_slave(sl)) { 182 int count = 0; 183 unsigned int tm = 750; 184 185 /* 750ms strong pullup (or delay) after the convert */ 186 if (w1_strong_pullup) 187 w1_next_pullup(dev, tm); 188 w1_write_8(dev, W1_CONVERT_TEMP); 189 if (!w1_strong_pullup) 190 msleep(tm); 191 192 if (!w1_reset_select_slave(sl)) { 193 194 w1_write_8(dev, W1_READ_SCRATCHPAD); 195 if ((count = w1_read_block(dev, rom, 9)) != 9) { 196 dev_warn(device, "w1_read_block() " 197 "returned %u instead of 9.\n", 198 count); 199 } 200 201 crc = w1_calc_crc8(rom, 8); 202 203 if (rom[8] == crc) 204 verdict = 1; 205 } 206 } 207 208 if (!w1_therm_check_rom(rom)) 209 break; 210 } 211 212 for (i = 0; i < 9; ++i) 213 c -= snprintf(buf + PAGE_SIZE - c, c, "%02x ", rom[i]); 214 c -= snprintf(buf + PAGE_SIZE - c, c, ": crc=%02x %s\n", 215 crc, (verdict) ? "YES" : "NO"); 216 if (verdict) 217 memcpy(sl->rom, rom, sizeof(sl->rom)); 218 else 219 dev_warn(device, "18S20 doesn't respond to CONVERT_TEMP.\n"); 220 221 for (i = 0; i < 9; ++i) 222 c -= snprintf(buf + PAGE_SIZE - c, c, "%02x ", sl->rom[i]); 223 224 c -= snprintf(buf + PAGE_SIZE - c, c, "t=%d\n", 225 w1_convert_temp(rom, sl->family->fid)); 226 mutex_unlock(&dev->mutex); 227 228 return PAGE_SIZE - c; 229} 230 231static int __init w1_therm_init(void) 232{ 233 int err, i; 234 235 for (i = 0; i < ARRAY_SIZE(w1_therm_families); ++i) { 236 err = w1_register_family(w1_therm_families[i].f); 237 if (err) 238 w1_therm_families[i].broken = 1; 239 } 240 241 return 0; 242} 243 244static void __exit w1_therm_fini(void) 245{ 246 int i; 247 248 for (i = 0; i < ARRAY_SIZE(w1_therm_families); ++i) 249 if (!w1_therm_families[i].broken) 250 w1_unregister_family(w1_therm_families[i].f); 251} 252 253module_init(w1_therm_init); 254module_exit(w1_therm_fini); 255