| 1 | /* SPDX-License-Identifier: GPL-2.0-or-later */ |
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| 2 | /* |
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| 3 | * lm75.h - Part of lm_sensors, Linux kernel modules for hardware monitoring |
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| 4 | * Copyright (c) 2003 Mark M. Hoffman <mhoffman@lightlink.com> |
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| 5 | */ |
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| 6 | |
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| 7 | /* |
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| 8 | * This file contains common code for encoding/decoding LM75 type |
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| 9 | * temperature readings, which are emulated by many of the chips |
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| 10 | * we support. As the user is unlikely to load more than one driver |
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| 11 | * which contains this code, we don't worry about the wasted space. |
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| 12 | */ |
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| 13 | |
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| 14 | #include <linux/minmax.h> |
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| 15 | #include <linux/types.h> |
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| 16 | |
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| 17 | /* straight from the datasheet */ |
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| 18 | #define LM75_TEMP_MIN (-55000) |
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| 19 | #define LM75_TEMP_MAX 125000 |
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| 20 | #define LM75_SHUTDOWN 0x01 |
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| 21 | |
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| 22 | /* |
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| 23 | * TEMP: 0.001C/bit (-55C to +125C) |
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| 24 | * REG: (0.5C/bit, two's complement) << 7 |
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| 25 | */ |
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| 26 | static inline u16 LM75_TEMP_TO_REG(long temp) |
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| 27 | { |
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| 28 | int ntemp = clamp_val(temp, LM75_TEMP_MIN, LM75_TEMP_MAX); |
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| 29 | |
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| 30 | ntemp += (ntemp < 0 ? -250 : 250); |
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| 31 | return (u16)((ntemp / 500) << 7); |
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| 32 | } |
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| 33 | |
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| 34 | static inline int LM75_TEMP_FROM_REG(u16 reg) |
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| 35 | { |
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| 36 | /* |
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| 37 | * use integer division instead of equivalent right shift to |
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| 38 | * guarantee arithmetic shift and preserve the sign |
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| 39 | */ |
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| 40 | return ((s16)reg / 128) * 500; |
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| 41 | } |
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| 42 | |
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