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1 | /* |
2 | lm75.h - Part of lm_sensors, Linux kernel modules for hardware |
3 | monitoring |
4 | Copyright (c) 2003 Mark M. Hoffman <mhoffman@lightlink.com> |
5 | |
6 | This program is free software; you can redistribute it and/or modify |
7 | it under the terms of the GNU General Public License as published by |
8 | the Free Software Foundation; either version 2 of the License, or |
9 | (at your option) any later version. |
10 | |
11 | This program is distributed in the hope that it will be useful, |
12 | but WITHOUT ANY WARRANTY; without even the implied warranty of |
13 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the |
14 | GNU General Public License for more details. |
15 | |
16 | You should have received a copy of the GNU General Public License |
17 | along with this program; if not, write to the Free Software |
18 | Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA. |
19 | */ |
20 | |
21 | /* |
22 | This file contains common code for encoding/decoding LM75 type |
23 | temperature readings, which are emulated by many of the chips |
24 | we support. As the user is unlikely to load more than one driver |
25 | which contains this code, we don't worry about the wasted space. |
26 | */ |
27 | |
28 | #include <linux/hwmon.h> |
29 | |
30 | /* straight from the datasheet */ |
31 | #define LM75_TEMP_MIN (-55000) |
32 | #define LM75_TEMP_MAX 125000 |
33 | |
34 | /* TEMP: 0.001C/bit (-55C to +125C) |
35 | REG: (0.5C/bit, two's complement) << 7 */ |
36 | static inline u16 LM75_TEMP_TO_REG(long temp) |
37 | { |
38 | int ntemp = SENSORS_LIMIT(temp, LM75_TEMP_MIN, LM75_TEMP_MAX); |
39 | ntemp += (ntemp<0 ? -250 : 250); |
40 | return (u16)((ntemp / 500) << 7); |
41 | } |
42 | |
43 | static inline int LM75_TEMP_FROM_REG(u16 reg) |
44 | { |
45 | /* use integer division instead of equivalent right shift to |
46 | guarantee arithmetic shift and preserve the sign */ |
47 | return ((s16)reg / 128) * 500; |
48 | } |
49 | |
50 |
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