Thomas Gleixner | 74ba920 | 2019-05-20 09:19:02 +0200 | [diff] [blame] | 1 | /* SPDX-License-Identifier: GPL-2.0-or-later */ |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 2 | /* |
Michal Orzel | 8cbf217 | 2020-04-30 16:05:34 +0200 | [diff] [blame] | 3 | * lm75.h - Part of lm_sensors, Linux kernel modules for hardware monitoring |
| 4 | * Copyright (c) 2003 Mark M. Hoffman <mhoffman@lightlink.com> |
| 5 | */ |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 6 | |
| 7 | /* |
Michal Orzel | 8cbf217 | 2020-04-30 16:05:34 +0200 | [diff] [blame] | 8 | * This file contains common code for encoding/decoding LM75 type |
| 9 | * temperature readings, which are emulated by many of the chips |
| 10 | * we support. As the user is unlikely to load more than one driver |
| 11 | * which contains this code, we don't worry about the wasted space. |
| 12 | */ |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 13 | |
Jean Delvare | 5a4c060 | 2013-03-18 21:19:49 +0100 | [diff] [blame] | 14 | #include <linux/kernel.h> |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 15 | |
| 16 | /* straight from the datasheet */ |
| 17 | #define LM75_TEMP_MIN (-55000) |
| 18 | #define LM75_TEMP_MAX 125000 |
Shubhrajyoti Datta | 9914518 | 2010-08-14 21:08:50 +0200 | [diff] [blame] | 19 | #define LM75_SHUTDOWN 0x01 |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 20 | |
Michal Orzel | 8cbf217 | 2020-04-30 16:05:34 +0200 | [diff] [blame] | 21 | /* |
| 22 | * TEMP: 0.001C/bit (-55C to +125C) |
| 23 | * REG: (0.5C/bit, two's complement) << 7 |
| 24 | */ |
Christian Hohnstaedt | 5bfedac | 2007-08-16 11:40:10 +0200 | [diff] [blame] | 25 | static inline u16 LM75_TEMP_TO_REG(long temp) |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 26 | { |
Guenter Roeck | 2a844c1 | 2013-01-09 08:09:34 -0800 | [diff] [blame] | 27 | int ntemp = clamp_val(temp, LM75_TEMP_MIN, LM75_TEMP_MAX); |
Michal Orzel | 8cbf217 | 2020-04-30 16:05:34 +0200 | [diff] [blame] | 28 | |
Frans Meulenbroeks | a01a684 | 2012-01-04 23:16:39 +0100 | [diff] [blame] | 29 | ntemp += (ntemp < 0 ? -250 : 250); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 30 | return (u16)((ntemp / 500) << 7); |
| 31 | } |
| 32 | |
| 33 | static inline int LM75_TEMP_FROM_REG(u16 reg) |
| 34 | { |
Michal Orzel | 8cbf217 | 2020-04-30 16:05:34 +0200 | [diff] [blame] | 35 | /* |
| 36 | * use integer division instead of equivalent right shift to |
| 37 | * guarantee arithmetic shift and preserve the sign |
| 38 | */ |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 39 | return ((s16)reg / 128) * 500; |
| 40 | } |