W1: feature, w1_therm.c use strong pullup and documentation
[linux-2.6.git] / drivers / w1 / slaves / w1_therm.c
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_bin(struct kobject *, struct bin_attribute *,
54                                  char *, loff_t, size_t);
55
56 static struct bin_attribute w1_therm_bin_attr = {
57         .attr = {
58                 .name = "w1_slave",
59                 .mode = S_IRUGO,
60         },
61         .size = W1_SLAVE_DATA_SIZE,
62         .read = w1_therm_read_bin,
63 };
64
65 static int w1_therm_add_slave(struct w1_slave *sl)
66 {
67         return sysfs_create_bin_file(&sl->dev.kobj, &w1_therm_bin_attr);
68 }
69
70 static void w1_therm_remove_slave(struct w1_slave *sl)
71 {
72         sysfs_remove_bin_file(&sl->dev.kobj, &w1_therm_bin_attr);
73 }
74
75 static struct w1_family_ops w1_therm_fops = {
76         .add_slave      = w1_therm_add_slave,
77         .remove_slave   = w1_therm_remove_slave,
78 };
79
80 static struct w1_family w1_therm_family_DS18S20 = {
81         .fid = W1_THERM_DS18S20,
82         .fops = &w1_therm_fops,
83 };
84
85 static struct w1_family w1_therm_family_DS18B20 = {
86         .fid = W1_THERM_DS18B20,
87         .fops = &w1_therm_fops,
88 };
89
90 static struct w1_family w1_therm_family_DS1822 = {
91         .fid = W1_THERM_DS1822,
92         .fops = &w1_therm_fops,
93 };
94
95 struct w1_therm_family_converter
96 {
97         u8                      broken;
98         u16                     reserved;
99         struct w1_family        *f;
100         int                     (*convert)(u8 rom[9]);
101 };
102
103 /* The return value is millidegrees Centigrade. */
104 static inline int w1_DS18B20_convert_temp(u8 rom[9]);
105 static inline int w1_DS18S20_convert_temp(u8 rom[9]);
106
107 static struct w1_therm_family_converter w1_therm_families[] = {
108         {
109                 .f              = &w1_therm_family_DS18S20,
110                 .convert        = w1_DS18S20_convert_temp
111         },
112         {
113                 .f              = &w1_therm_family_DS1822,
114                 .convert        = w1_DS18B20_convert_temp
115         },
116         {
117                 .f              = &w1_therm_family_DS18B20,
118                 .convert        = w1_DS18B20_convert_temp
119         },
120 };
121
122 static inline int w1_DS18B20_convert_temp(u8 rom[9])
123 {
124         s16 t = (rom[1] << 8) | rom[0];
125         t = t*1000/16;
126         return t;
127 }
128
129 static inline int w1_DS18S20_convert_temp(u8 rom[9])
130 {
131         int t, h;
132
133         if (!rom[7])
134                 return 0;
135
136         if (rom[1] == 0)
137                 t = ((s32)rom[0] >> 1)*1000;
138         else
139                 t = 1000*(-1*(s32)(0x100-rom[0]) >> 1);
140
141         t -= 250;
142         h = 1000*((s32)rom[7] - (s32)rom[6]);
143         h /= (s32)rom[7];
144         t += h;
145
146         return t;
147 }
148
149 static inline int w1_convert_temp(u8 rom[9], u8 fid)
150 {
151         int i;
152
153         for (i = 0; i < ARRAY_SIZE(w1_therm_families); ++i)
154                 if (w1_therm_families[i].f->fid == fid)
155                         return w1_therm_families[i].convert(rom);
156
157         return 0;
158 }
159
160 static int w1_therm_check_rom(u8 rom[9])
161 {
162         int i;
163
164         for (i=0; i<sizeof(bad_roms)/9; ++i)
165                 if (!memcmp(bad_roms[i], rom, 9))
166                         return 1;
167
168         return 0;
169 }
170
171 static ssize_t w1_therm_read_bin(struct kobject *kobj,
172                                  struct bin_attribute *bin_attr,
173                                  char *buf, loff_t off, size_t count)
174 {
175         struct w1_slave *sl = kobj_to_w1_slave(kobj);
176         struct w1_master *dev = sl->master;
177         u8 rom[9], crc, verdict;
178         int i, max_trying = 10;
179
180         mutex_lock(&sl->master->mutex);
181
182         if (off > W1_SLAVE_DATA_SIZE) {
183                 count = 0;
184                 goto out;
185         }
186         if (off + count > W1_SLAVE_DATA_SIZE) {
187                 count = 0;
188                 goto out;
189         }
190
191         memset(buf, 0, count);
192         memset(rom, 0, sizeof(rom));
193
194         count = 0;
195         verdict = 0;
196         crc = 0;
197
198         while (max_trying--) {
199                 if (!w1_reset_select_slave(sl)) {
200                         int count = 0;
201                         unsigned int tm = 750;
202
203                         /* 750ms strong pullup (or delay) after the convert */
204                         if (w1_strong_pullup)
205                                 w1_next_pullup(dev, tm);
206                         w1_write_8(dev, W1_CONVERT_TEMP);
207                         if (!w1_strong_pullup)
208                                 msleep(tm);
209
210                         if (!w1_reset_select_slave(sl)) {
211
212                                 w1_write_8(dev, W1_READ_SCRATCHPAD);
213                                 if ((count = w1_read_block(dev, rom, 9)) != 9) {
214                                         dev_warn(&dev->dev, "w1_read_block() returned %d instead of 9.\n", count);
215                                 }
216
217                                 crc = w1_calc_crc8(rom, 8);
218
219                                 if (rom[8] == crc)
220                                         verdict = 1;
221                         }
222                 }
223
224                 if (!w1_therm_check_rom(rom))
225                         break;
226         }
227
228         for (i = 0; i < 9; ++i)
229                 count += sprintf(buf + count, "%02x ", rom[i]);
230         count += sprintf(buf + count, ": crc=%02x %s\n",
231                            crc, (verdict) ? "YES" : "NO");
232         if (verdict)
233                 memcpy(sl->rom, rom, sizeof(sl->rom));
234         else
235                 dev_warn(&dev->dev, "18S20 doesn't respond to CONVERT_TEMP.\n");
236
237         for (i = 0; i < 9; ++i)
238                 count += sprintf(buf + count, "%02x ", sl->rom[i]);
239
240         count += sprintf(buf + count, "t=%d\n", w1_convert_temp(rom, sl->family->fid));
241 out:
242         mutex_unlock(&dev->mutex);
243
244         return count;
245 }
246
247 static int __init w1_therm_init(void)
248 {
249         int err, i;
250
251         for (i = 0; i < ARRAY_SIZE(w1_therm_families); ++i) {
252                 err = w1_register_family(w1_therm_families[i].f);
253                 if (err)
254                         w1_therm_families[i].broken = 1;
255         }
256
257         return 0;
258 }
259
260 static void __exit w1_therm_fini(void)
261 {
262         int i;
263
264         for (i = 0; i < ARRAY_SIZE(w1_therm_families); ++i)
265                 if (!w1_therm_families[i].broken)
266                         w1_unregister_family(w1_therm_families[i].f);
267 }
268
269 module_init(w1_therm_init);
270 module_exit(w1_therm_fini);