42 lines
1.1 KiB
C
42 lines
1.1 KiB
C
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/* SPDX-License-Identifier: GPL-2.0-or-later */
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/*
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* lm75.h - Part of lm_sensors, Linux kernel modules for hardware monitoring
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* Copyright (c) 2003 Mark M. Hoffman <mhoffman@lightlink.com>
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*/
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/*
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* This file contains common code for encoding/decoding LM75 type
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* temperature readings, which are emulated by many of the chips
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* we support. As the user is unlikely to load more than one driver
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* which contains this code, we don't worry about the wasted space.
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*/
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#include <linux/minmax.h>
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#include <linux/types.h>
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/* straight from the datasheet */
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#define LM75_TEMP_MIN (-55000)
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#define LM75_TEMP_MAX 125000
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#define LM75_SHUTDOWN 0x01
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/*
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* TEMP: 0.001C/bit (-55C to +125C)
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* REG: (0.5C/bit, two's complement) << 7
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*/
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static inline u16 LM75_TEMP_TO_REG(long temp)
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{
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int ntemp = clamp_val(temp, LM75_TEMP_MIN, LM75_TEMP_MAX);
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ntemp += (ntemp < 0 ? -250 : 250);
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return (u16)((ntemp / 500) << 7);
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}
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static inline int LM75_TEMP_FROM_REG(u16 reg)
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{
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/*
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* use integer division instead of equivalent right shift to
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* guarantee arithmetic shift and preserve the sign
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*/
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return ((s16)reg / 128) * 500;
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}
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