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428 lines
11 KiB
428 lines
11 KiB
Kernel driver lm90 |
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================== |
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Supported chips: |
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* National Semiconductor LM90 |
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Prefix: 'lm90' |
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Addresses scanned: I2C 0x4c |
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Datasheet: Publicly available at the National Semiconductor website |
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http://www.national.com/pf/LM/LM90.html |
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* National Semiconductor LM89 |
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Prefix: 'lm89' (no auto-detection) |
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Addresses scanned: I2C 0x4c and 0x4d |
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Datasheet: Publicly available at the National Semiconductor website |
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http://www.national.com/mpf/LM/LM89.html |
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* National Semiconductor LM99 |
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Prefix: 'lm99' |
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Addresses scanned: I2C 0x4c and 0x4d |
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Datasheet: Publicly available at the National Semiconductor website |
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http://www.national.com/pf/LM/LM99.html |
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* National Semiconductor LM86 |
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Prefix: 'lm86' |
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Addresses scanned: I2C 0x4c |
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Datasheet: Publicly available at the National Semiconductor website |
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http://www.national.com/mpf/LM/LM86.html |
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* Analog Devices ADM1032 |
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Prefix: 'adm1032' |
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Addresses scanned: I2C 0x4c and 0x4d |
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Datasheet: Publicly available at the ON Semiconductor website |
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https://www.onsemi.com/PowerSolutions/product.do?id=ADM1032 |
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* Analog Devices ADT7461 |
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Prefix: 'adt7461' |
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Addresses scanned: I2C 0x4c and 0x4d |
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Datasheet: Publicly available at the ON Semiconductor website |
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https://www.onsemi.com/PowerSolutions/product.do?id=ADT7461 |
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* Analog Devices ADT7461A |
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Prefix: 'adt7461a' |
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Addresses scanned: I2C 0x4c and 0x4d |
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Datasheet: Publicly available at the ON Semiconductor website |
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https://www.onsemi.com/PowerSolutions/product.do?id=ADT7461A |
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* ON Semiconductor NCT1008 |
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Prefix: 'nct1008' |
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Addresses scanned: I2C 0x4c and 0x4d |
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Datasheet: Publicly available at the ON Semiconductor website |
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https://www.onsemi.com/PowerSolutions/product.do?id=NCT1008 |
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* Maxim MAX6646 |
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Prefix: 'max6646' |
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Addresses scanned: I2C 0x4d |
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Datasheet: Publicly available at the Maxim website |
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http://www.maxim-ic.com/quick_view2.cfm/qv_pk/3497 |
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* Maxim MAX6647 |
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Prefix: 'max6646' |
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Addresses scanned: I2C 0x4e |
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Datasheet: Publicly available at the Maxim website |
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http://www.maxim-ic.com/quick_view2.cfm/qv_pk/3497 |
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* Maxim MAX6648 |
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Prefix: 'max6646' |
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Addresses scanned: I2C 0x4c |
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Datasheet: Publicly available at the Maxim website |
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http://www.maxim-ic.com/quick_view2.cfm/qv_pk/3500 |
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* Maxim MAX6649 |
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Prefix: 'max6646' |
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Addresses scanned: I2C 0x4c |
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Datasheet: Publicly available at the Maxim website |
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http://www.maxim-ic.com/quick_view2.cfm/qv_pk/3497 |
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* Maxim MAX6654 |
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Prefix: 'max6654' |
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Addresses scanned: I2C 0x18, 0x19, 0x1a, 0x29, 0x2a, 0x2b, |
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0x4c, 0x4d and 0x4e |
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Datasheet: Publicly available at the Maxim website |
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https://www.maximintegrated.com/en/products/sensors/MAX6654.html |
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* Maxim MAX6657 |
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Prefix: 'max6657' |
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Addresses scanned: I2C 0x4c |
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Datasheet: Publicly available at the Maxim website |
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http://www.maxim-ic.com/quick_view2.cfm/qv_pk/2578 |
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* Maxim MAX6658 |
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Prefix: 'max6657' |
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Addresses scanned: I2C 0x4c |
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Datasheet: Publicly available at the Maxim website |
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http://www.maxim-ic.com/quick_view2.cfm/qv_pk/2578 |
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* Maxim MAX6659 |
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Prefix: 'max6659' |
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Addresses scanned: I2C 0x4c, 0x4d, 0x4e |
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Datasheet: Publicly available at the Maxim website |
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http://www.maxim-ic.com/quick_view2.cfm/qv_pk/2578 |
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* Maxim MAX6680 |
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Prefix: 'max6680' |
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Addresses scanned: I2C 0x18, 0x19, 0x1a, 0x29, 0x2a, 0x2b, |
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0x4c, 0x4d and 0x4e |
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Datasheet: Publicly available at the Maxim website |
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http://www.maxim-ic.com/quick_view2.cfm/qv_pk/3370 |
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* Maxim MAX6681 |
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Prefix: 'max6680' |
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Addresses scanned: I2C 0x18, 0x19, 0x1a, 0x29, 0x2a, 0x2b, |
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0x4c, 0x4d and 0x4e |
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Datasheet: Publicly available at the Maxim website |
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http://www.maxim-ic.com/quick_view2.cfm/qv_pk/3370 |
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* Maxim MAX6692 |
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Prefix: 'max6646' |
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Addresses scanned: I2C 0x4c |
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Datasheet: Publicly available at the Maxim website |
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http://www.maxim-ic.com/quick_view2.cfm/qv_pk/3500 |
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* Maxim MAX6695 |
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Prefix: 'max6695' |
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Addresses scanned: I2C 0x18 |
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Datasheet: Publicly available at the Maxim website |
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http://www.maxim-ic.com/datasheet/index.mvp/id/4199 |
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* Maxim MAX6696 |
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Prefix: 'max6695' |
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Addresses scanned: I2C 0x18, 0x19, 0x1a, 0x29, 0x2a, 0x2b, |
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0x4c, 0x4d and 0x4e |
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Datasheet: Publicly available at the Maxim website |
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http://www.maxim-ic.com/datasheet/index.mvp/id/4199 |
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* Winbond/Nuvoton W83L771W/G |
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Prefix: 'w83l771' |
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Addresses scanned: I2C 0x4c |
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Datasheet: No longer available |
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* Winbond/Nuvoton W83L771AWG/ASG |
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Prefix: 'w83l771' |
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Addresses scanned: I2C 0x4c |
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Datasheet: Not publicly available, can be requested from Nuvoton |
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* Philips/NXP SA56004X |
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Prefix: 'sa56004' |
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Addresses scanned: I2C 0x48 through 0x4F |
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Datasheet: Publicly available at NXP website |
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http://ics.nxp.com/products/interface/datasheet/sa56004x.pdf |
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* GMT G781 |
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Prefix: 'g781' |
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Addresses scanned: I2C 0x4c, 0x4d |
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Datasheet: Not publicly available from GMT |
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* Texas Instruments TMP451 |
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Prefix: 'tmp451' |
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Addresses scanned: I2C 0x4c |
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Datasheet: Publicly available at TI website |
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https://www.ti.com/litv/pdf/sbos686 |
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* Texas Instruments TMP461 |
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Prefix: 'tmp461' |
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Addresses scanned: I2C 0x48 through 0x4F |
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Datasheet: Publicly available at TI website |
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https://www.ti.com/lit/gpn/tmp461 |
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Author: Jean Delvare <[email protected]> |
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Description |
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----------- |
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The LM90 is a digital temperature sensor. It senses its own temperature as |
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well as the temperature of up to one external diode. It is compatible |
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with many other devices, many of which are supported by this driver. |
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Note that there is no easy way to differentiate between the MAX6657, |
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MAX6658 and MAX6659 variants. The extra features of the MAX6659 are only |
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supported by this driver if the chip is located at address 0x4d or 0x4e, |
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or if the chip type is explicitly selected as max6659. |
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The MAX6680 and MAX6681 only differ in their pinout, therefore they obviously |
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can't (and don't need to) be distinguished. |
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The specificity of this family of chipsets over the ADM1021/LM84 |
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family is that it features critical limits with hysteresis, and an |
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increased resolution of the remote temperature measurement. |
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The different chipsets of the family are not strictly identical, although |
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very similar. For reference, here comes a non-exhaustive list of specific |
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features: |
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LM90: |
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* Filter and alert configuration register at 0xBF. |
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* ALERT is triggered by temperatures over critical limits. |
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LM86 and LM89: |
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* Same as LM90 |
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* Better external channel accuracy |
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LM99: |
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* Same as LM89 |
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* External temperature shifted by 16 degrees down |
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ADM1032: |
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* Consecutive alert register at 0x22. |
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* Conversion averaging. |
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* Up to 64 conversions/s. |
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* ALERT is triggered by open remote sensor. |
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* SMBus PEC support for Write Byte and Receive Byte transactions. |
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ADT7461, ADT7461A, NCT1008: |
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* Extended temperature range (breaks compatibility) |
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* Lower resolution for remote temperature |
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MAX6654: |
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* Better local resolution |
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* Selectable address |
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* Remote sensor type selection |
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* Extended temperature range |
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* Extended resolution only available when conversion rate <= 1 Hz |
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MAX6657 and MAX6658: |
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* Better local resolution |
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* Remote sensor type selection |
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MAX6659: |
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* Better local resolution |
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* Selectable address |
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* Second critical temperature limit |
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* Remote sensor type selection |
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MAX6680 and MAX6681: |
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* Selectable address |
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* Remote sensor type selection |
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MAX6695 and MAX6696: |
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* Better local resolution |
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* Selectable address (max6696) |
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* Second critical temperature limit |
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* Two remote sensors |
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W83L771W/G |
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* The G variant is lead-free, otherwise similar to the W. |
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* Filter and alert configuration register at 0xBF |
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* Moving average (depending on conversion rate) |
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W83L771AWG/ASG |
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* Successor of the W83L771W/G, same features. |
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* The AWG and ASG variants only differ in package format. |
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* Diode ideality factor configuration (remote sensor) at 0xE3 |
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SA56004X: |
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* Better local resolution |
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All temperature values are given in degrees Celsius. Resolution |
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is 1.0 degree for the local temperature, 0.125 degree for the remote |
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temperature, except for the MAX6654, MAX6657, MAX6658 and MAX6659 which have |
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a resolution of 0.125 degree for both temperatures. |
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Each sensor has its own high and low limits, plus a critical limit. |
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Additionally, there is a relative hysteresis value common to both critical |
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values. To make life easier to user-space applications, two absolute values |
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are exported, one for each channel, but these values are of course linked. |
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Only the local hysteresis can be set from user-space, and the same delta |
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applies to the remote hysteresis. |
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The lm90 driver will not update its values more frequently than configured with |
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the update_interval attribute; reading them more often will do no harm, but will |
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return 'old' values. |
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SMBus Alert Support |
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------------------- |
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This driver has basic support for SMBus alert. When an alert is received, |
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the status register is read and the faulty temperature channel is logged. |
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The Analog Devices chips (ADM1032, ADT7461 and ADT7461A) and ON |
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Semiconductor chips (NCT1008) do not implement the SMBus alert protocol |
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properly so additional care is needed: the ALERT output is disabled when |
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an alert is received, and is re-enabled only when the alarm is gone. |
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Otherwise the chip would block alerts from other chips in the bus as long |
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as the alarm is active. |
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PEC Support |
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----------- |
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The ADM1032 is the only chip of the family which supports PEC. It does |
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not support PEC on all transactions though, so some care must be taken. |
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When reading a register value, the PEC byte is computed and sent by the |
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ADM1032 chip. However, in the case of a combined transaction (SMBus Read |
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Byte), the ADM1032 computes the CRC value over only the second half of |
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the message rather than its entirety, because it thinks the first half |
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of the message belongs to a different transaction. As a result, the CRC |
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value differs from what the SMBus master expects, and all reads fail. |
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For this reason, the lm90 driver will enable PEC for the ADM1032 only if |
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the bus supports the SMBus Send Byte and Receive Byte transaction types. |
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These transactions will be used to read register values, instead of |
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SMBus Read Byte, and PEC will work properly. |
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Additionally, the ADM1032 doesn't support SMBus Send Byte with PEC. |
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Instead, it will try to write the PEC value to the register (because the |
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SMBus Send Byte transaction with PEC is similar to a Write Byte transaction |
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without PEC), which is not what we want. Thus, PEC is explicitly disabled |
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on SMBus Send Byte transactions in the lm90 driver. |
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PEC on byte data transactions represents a significant increase in bandwidth |
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usage (+33% for writes, +25% for reads) in normal conditions. With the need |
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to use two SMBus transaction for reads, this overhead jumps to +50%. Worse, |
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two transactions will typically mean twice as much delay waiting for |
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transaction completion, effectively doubling the register cache refresh time. |
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I guess reliability comes at a price, but it's quite expensive this time. |
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So, as not everyone might enjoy the slowdown, PEC can be disabled through |
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sysfs. Just write 0 to the "pec" file and PEC will be disabled. Write 1 |
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to that file to enable PEC again.
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