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50 lines
1.7 KiB
C
50 lines
1.7 KiB
C
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/*
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lm75.h - Part of lm_sensors, Linux kernel modules for hardware
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monitoring
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Copyright (c) 2003 Mark M. Hoffman <mhoffman@lightlink.com>
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This program is free software; you can redistribute it and/or modify
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it under the terms of the GNU General Public License as published by
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the Free Software Foundation; either version 2 of the License, or
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(at your option) any later version.
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This program is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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GNU General Public License for more details.
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You should have received a copy of the GNU General Public License
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along with this program; if not, write to the Free Software
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Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
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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/i2c-sensor.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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/* TEMP: 0.001C/bit (-55C to +125C)
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REG: (0.5C/bit, two's complement) << 7 */
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static inline u16 LM75_TEMP_TO_REG(int temp)
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{
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int ntemp = SENSORS_LIMIT(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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/* use integer division instead of equivalent right shift to
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guarantee arithmetic shift and preserve the sign */
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return ((s16)reg / 128) * 500;
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}
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