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MAX31725/MAX31726 are local temperature sensors with +/- 0.5 degree Celsius accuracy and 16-bit (0.00390625 degrees Celsius) resolution. They have a register mapping and encoding compatible with the lm75 series drivers. Address scan and extended temperature range are not supported by this patch. Tested on real hardware and verified temperature readings are correct. Signed-off-by: Kun Yi <kunyi@google.com> Signed-off-by: Guenter Roeck <linux@roeck-us.net>
93 lines
3.9 KiB
Text
93 lines
3.9 KiB
Text
Kernel driver lm75
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==================
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Supported chips:
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* National Semiconductor LM75
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Prefix: 'lm75'
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Addresses scanned: I2C 0x48 - 0x4f
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Datasheet: Publicly available at the National Semiconductor website
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http://www.national.com/
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* National Semiconductor LM75A
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Prefix: 'lm75a'
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Addresses scanned: I2C 0x48 - 0x4f
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Datasheet: Publicly available at the National Semiconductor website
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http://www.national.com/
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* Dallas Semiconductor (now Maxim) DS75, DS1775, DS7505
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Prefixes: 'ds75', 'ds1775', 'ds7505'
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Addresses scanned: none
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Datasheet: Publicly available at the Maxim website
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http://www.maximintegrated.com/
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* Maxim MAX6625, MAX6626, MAX31725, MAX31726
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Prefixes: 'max6625', 'max6626', 'max31725', 'max31726'
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Addresses scanned: none
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Datasheet: Publicly available at the Maxim website
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http://www.maxim-ic.com/
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* Microchip (TelCom) TCN75
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Prefix: 'tcn75'
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Addresses scanned: none
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Datasheet: Publicly available at the Microchip website
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http://www.microchip.com/
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* Microchip MCP9800, MCP9801, MCP9802, MCP9803
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Prefix: 'mcp980x'
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Addresses scanned: none
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Datasheet: Publicly available at the Microchip website
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http://www.microchip.com/
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* Analog Devices ADT75
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Prefix: 'adt75'
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Addresses scanned: none
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Datasheet: Publicly available at the Analog Devices website
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http://www.analog.com/adt75
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* ST Microelectronics STDS75
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Prefix: 'stds75'
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Addresses scanned: none
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Datasheet: Publicly available at the ST website
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http://www.st.com/internet/analog/product/121769.jsp
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* Texas Instruments TMP100, TMP101, TMP105, TMP112, TMP75, TMP75C, TMP175, TMP275
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Prefixes: 'tmp100', 'tmp101', 'tmp105', 'tmp112', 'tmp175', 'tmp75', 'tmp75c', 'tmp275'
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Addresses scanned: none
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Datasheet: Publicly available at the Texas Instruments website
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http://www.ti.com/product/tmp100
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http://www.ti.com/product/tmp101
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http://www.ti.com/product/tmp105
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http://www.ti.com/product/tmp112
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http://www.ti.com/product/tmp75
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http://www.ti.com/product/tmp75c
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http://www.ti.com/product/tmp175
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http://www.ti.com/product/tmp275
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* NXP LM75B
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Prefix: 'lm75b'
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Addresses scanned: none
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Datasheet: Publicly available at the NXP website
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http://www.nxp.com/documents/data_sheet/LM75B.pdf
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Author: Frodo Looijaard <frodol@dds.nl>
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Description
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-----------
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The LM75 implements one temperature sensor. Limits can be set through the
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Overtemperature Shutdown register and Hysteresis register. Each value can be
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set and read to half-degree accuracy.
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An alarm is issued (usually to a connected LM78) when the temperature
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gets higher then the Overtemperature Shutdown value; it stays on until
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the temperature falls below the Hysteresis value.
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All temperatures are in degrees Celsius, and are guaranteed within a
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range of -55 to +125 degrees.
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The driver caches the values for a period varying between 1 second for the
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slowest chips and 125 ms for the fastest chips; reading it more often
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will do no harm, but will return 'old' values.
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The original LM75 was typically used in combination with LM78-like chips
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on PC motherboards, to measure the temperature of the processor(s). Clones
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are now used in various embedded designs.
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The LM75 is essentially an industry standard; there may be other
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LM75 clones not listed here, with or without various enhancements,
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that are supported. The clones are not detected by the driver, unless
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they reproduce the exact register tricks of the original LM75, and must
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therefore be instantiated explicitly. Higher resolution up to 16-bit
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is supported by this driver, other specific enhancements are not.
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The LM77 is not supported, contrary to what we pretended for a long time.
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Both chips are simply not compatible, value encoding differs.
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