FreeBSD/Linux Kernel Cross Reference
sys/drivers/hwmon/lm75.h

     /*
         lm75.h - Part of lm_sensors, Linux kernel modules for hardware
                   monitoring
         Copyright (c) 2003 Mark M. Hoffman <mhoffman@lightlink.com>
     
         This program is free software; you can redistribute it and/or modify
         it under the terms of the GNU General Public License as published by
         the Free Software Foundation; either version 2 of the License, or
         (at your option) any later version.
    
        This program is distributed in the hope that it will be useful,
        but WITHOUT ANY WARRANTY; without even the implied warranty of
        MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
        GNU General Public License for more details.
    
        You should have received a copy of the GNU General Public License
        along with this program; if not, write to the Free Software
        Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
    */
    
    /*
        This file contains common code for encoding/decoding LM75 type
        temperature readings, which are emulated by many of the chips
        we support.  As the user is unlikely to load more than one driver
        which contains this code, we don't worry about the wasted space.
    */
    
    #include <linux/hwmon.h>
    
    /* straight from the datasheet */
    #define LM75_TEMP_MIN (-55000)
    #define LM75_TEMP_MAX 125000
    #define LM75_SHUTDOWN 0x01
    
    /* TEMP: 0.001C/bit (-55C to +125C)
       REG: (0.5C/bit, two's complement) << 7 */
    static inline u16 LM75_TEMP_TO_REG(long temp)
    {
            int ntemp = SENSORS_LIMIT(temp, LM75_TEMP_MIN, LM75_TEMP_MAX);
            ntemp += (ntemp < 0 ? -250 : 250);
            return (u16)((ntemp / 500) << 7);
    }
    
    static inline int LM75_TEMP_FROM_REG(u16 reg)
    {
            /* use integer division instead of equivalent right shift to
               guarantee arithmetic shift and preserve the sign */
            return ((s16)reg / 128) * 500;
    }

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