1 /* SPDX-License-Identifier: GPL-2.0-or-later */
2 /*
3 lm75.h - Part of lm_sensors, Linux kernel modules for hardware
4 monitoring
5 Copyright (c) 2003 Mark M. Hoffman <mhoffman@lightlink.com>
6
7 */
8
9 /*
10 This file contains common code for encoding/decoding LM75 type
11 temperature readings, which are emulated by many of the chips
12 we support. As the user is unlikely to load more than one driver
13 which contains this code, we don't worry about the wasted space.
14 */
15
16 #include <linux/kernel.h>
17
18 /* straight from the datasheet */
19 #define LM75_TEMP_MIN (-55000)
20 #define LM75_TEMP_MAX 125000
21 #define LM75_SHUTDOWN 0x01
22
23 /* TEMP: 0.001C/bit (-55C to +125C)
24 REG: (0.5C/bit, two's complement) << 7 */
25 static inline u16 LM75_TEMP_TO_REG(long temp)
26 {
27 int ntemp = clamp_val(temp, LM75_TEMP_MIN, LM75_TEMP_MAX);
28 ntemp += (ntemp < 0 ? -250 : 250);
29 return (u16)((ntemp / 500) << 7);
30 }
31
32 static inline int LM75_TEMP_FROM_REG(u16 reg)
33 {
34 /* use integer division instead of equivalent right shift to
35 guarantee arithmetic shift and preserve the sign */
36 return ((s16)reg / 128) * 500;
37 }