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 */
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
w1_therm_add_slave(struct w1_slave * sl)59 static int w1_therm_add_slave(struct w1_slave *sl)
60 {
61 return device_create_file(&sl->dev, &w1_therm_attr);
62 }
63
w1_therm_remove_slave(struct w1_slave * sl)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 static struct w1_family w1_therm_family_DS28EA00 = {
90 .fid = W1_THERM_DS28EA00,
91 .fops = &w1_therm_fops,
92 };
93
94 struct w1_therm_family_converter
95 {
96 u8 broken;
97 u16 reserved;
98 struct w1_family *f;
99 int (*convert)(u8 rom[9]);
100 };
101
102 /* The return value is millidegrees Centigrade. */
103 static inline int w1_DS18B20_convert_temp(u8 rom[9]);
104 static inline int w1_DS18S20_convert_temp(u8 rom[9]);
105
106 static struct w1_therm_family_converter w1_therm_families[] = {
107 {
108 .f = &w1_therm_family_DS18S20,
109 .convert = w1_DS18S20_convert_temp
110 },
111 {
112 .f = &w1_therm_family_DS1822,
113 .convert = w1_DS18B20_convert_temp
114 },
115 {
116 .f = &w1_therm_family_DS18B20,
117 .convert = w1_DS18B20_convert_temp
118 },
119 {
120 .f = &w1_therm_family_DS28EA00,
121 .convert = w1_DS18B20_convert_temp
122 },
123 };
124
w1_DS18B20_convert_temp(u8 rom[9])125 static inline int w1_DS18B20_convert_temp(u8 rom[9])
126 {
127 s16 t = le16_to_cpup((__le16 *)rom);
128 return t*1000/16;
129 }
130
w1_DS18S20_convert_temp(u8 rom[9])131 static inline int w1_DS18S20_convert_temp(u8 rom[9])
132 {
133 int t, h;
134
135 if (!rom[7])
136 return 0;
137
138 if (rom[1] == 0)
139 t = ((s32)rom[0] >> 1)*1000;
140 else
141 t = 1000*(-1*(s32)(0x100-rom[0]) >> 1);
142
143 t -= 250;
144 h = 1000*((s32)rom[7] - (s32)rom[6]);
145 h /= (s32)rom[7];
146 t += h;
147
148 return t;
149 }
150
w1_convert_temp(u8 rom[9],u8 fid)151 static inline int w1_convert_temp(u8 rom[9], u8 fid)
152 {
153 int i;
154
155 for (i = 0; i < ARRAY_SIZE(w1_therm_families); ++i)
156 if (w1_therm_families[i].f->fid == fid)
157 return w1_therm_families[i].convert(rom);
158
159 return 0;
160 }
161
w1_therm_check_rom(u8 rom[9])162 static int w1_therm_check_rom(u8 rom[9])
163 {
164 int i;
165
166 for (i=0; i<sizeof(bad_roms)/9; ++i)
167 if (!memcmp(bad_roms[i], rom, 9))
168 return 1;
169
170 return 0;
171 }
172
w1_therm_read(struct device * device,struct device_attribute * attr,char * buf)173 static ssize_t w1_therm_read(struct device *device,
174 struct device_attribute *attr, char *buf)
175 {
176 struct w1_slave *sl = dev_to_w1_slave(device);
177 struct w1_master *dev = sl->master;
178 u8 rom[9], crc, verdict, external_power;
179 int i, max_trying = 10;
180 ssize_t c = PAGE_SIZE;
181
182 i = mutex_lock_interruptible(&dev->mutex);
183 if (i != 0)
184 return i;
185
186 memset(rom, 0, sizeof(rom));
187
188 verdict = 0;
189 crc = 0;
190
191 while (max_trying--) {
192 if (!w1_reset_select_slave(sl)) {
193 int count = 0;
194 unsigned int tm = 750;
195 unsigned long sleep_rem;
196
197 w1_write_8(dev, W1_READ_PSUPPLY);
198 external_power = w1_read_8(dev);
199
200 if (w1_reset_select_slave(sl))
201 continue;
202
203 /* 750ms strong pullup (or delay) after the convert */
204 if (!external_power && w1_strong_pullup)
205 w1_next_pullup(dev, tm);
206
207 w1_write_8(dev, W1_CONVERT_TEMP);
208
209 if (external_power) {
210 mutex_unlock(&dev->mutex);
211
212 sleep_rem = msleep_interruptible(tm);
213 if (sleep_rem != 0)
214 return -EINTR;
215
216 i = mutex_lock_interruptible(&dev->mutex);
217 if (i != 0)
218 return i;
219 } else if (!w1_strong_pullup) {
220 sleep_rem = msleep_interruptible(tm);
221 if (sleep_rem != 0) {
222 mutex_unlock(&dev->mutex);
223 return -EINTR;
224 }
225 }
226
227 if (!w1_reset_select_slave(sl)) {
228
229 w1_write_8(dev, W1_READ_SCRATCHPAD);
230 if ((count = w1_read_block(dev, rom, 9)) != 9) {
231 dev_warn(device, "w1_read_block() "
232 "returned %u instead of 9.\n",
233 count);
234 }
235
236 crc = w1_calc_crc8(rom, 8);
237
238 if (rom[8] == crc)
239 verdict = 1;
240 }
241 }
242
243 if (!w1_therm_check_rom(rom))
244 break;
245 }
246
247 for (i = 0; i < 9; ++i)
248 c -= snprintf(buf + PAGE_SIZE - c, c, "%02x ", rom[i]);
249 c -= snprintf(buf + PAGE_SIZE - c, c, ": crc=%02x %s\n",
250 crc, (verdict) ? "YES" : "NO");
251 if (verdict)
252 memcpy(sl->rom, rom, sizeof(sl->rom));
253 else
254 dev_warn(device, "18S20 doesn't respond to CONVERT_TEMP.\n");
255
256 for (i = 0; i < 9; ++i)
257 c -= snprintf(buf + PAGE_SIZE - c, c, "%02x ", sl->rom[i]);
258
259 c -= snprintf(buf + PAGE_SIZE - c, c, "t=%d\n",
260 w1_convert_temp(rom, sl->family->fid));
261 mutex_unlock(&dev->mutex);
262
263 return PAGE_SIZE - c;
264 }
265
w1_therm_init(void)266 static int __init w1_therm_init(void)
267 {
268 int err, i;
269
270 for (i = 0; i < ARRAY_SIZE(w1_therm_families); ++i) {
271 err = w1_register_family(w1_therm_families[i].f);
272 if (err)
273 w1_therm_families[i].broken = 1;
274 }
275
276 return 0;
277 }
278
w1_therm_fini(void)279 static void __exit w1_therm_fini(void)
280 {
281 int i;
282
283 for (i = 0; i < ARRAY_SIZE(w1_therm_families); ++i)
284 if (!w1_therm_families[i].broken)
285 w1_unregister_family(w1_therm_families[i].f);
286 }
287
288 module_init(w1_therm_init);
289 module_exit(w1_therm_fini);
290