Kernel driver lm90
==================
Supported chips:
* National Semiconductor LM84
Prefix: 'lm84'
Addresses scanned: I2C 0x18 - 0x1a, 0x29 - 0x2b, 0x4c - 0x4e
Datasheet: Publicly available at the National Semiconductor website
* National Semiconductor LM90
Prefix: 'lm90'
Addresses scanned: I2C 0x4c
Datasheet: Publicly available at the National Semiconductor website
http://www.national.com/pf/LM/LM90.html
* National Semiconductor LM89
Prefix: 'lm89' (no auto-detection)
Addresses scanned: I2C 0x4c and 0x4d
Datasheet: Publicly available at the National Semiconductor website
http://www.national.com/mpf/LM/LM89.html
* National Semiconductor LM99
Prefix: 'lm99'
Addresses scanned: I2C 0x4c and 0x4d
Datasheet: Publicly available at the National Semiconductor website
http://www.national.com/pf/LM/LM99.html
* National Semiconductor LM86
Prefix: 'lm86'
Addresses scanned: I2C 0x4c
Datasheet: Publicly available at the National Semiconductor website
http://www.national.com/mpf/LM/LM86.html
* Analog Devices ADM1020
Prefix: 'adm1020'
Addresses scanned: I2C 0x4c - 0x4e
Datasheet: Publicly available at the Analog Devices website
* Analog Devices ADM1021
Prefix: 'adm1021'
Addresses scanned: I2C 0x18 - 0x1a, 0x29 - 0x2b, 0x4c - 0x4e
Datasheet: Publicly available at the Analog Devices website
* Analog Devices ADM1021A/ADM1023
Prefix: 'adm1023'
Addresses scanned: I2C 0x18 - 0x1a, 0x29 - 0x2b, 0x4c - 0x4e
Datasheet: Publicly available at the Analog Devices website
* Analog Devices ADM1032
Prefix: 'adm1032'
Addresses scanned: I2C 0x4c and 0x4d
Datasheet: Publicly available at the ON Semiconductor website
https://www.onsemi.com/PowerSolutions/product.do?id=ADM1032
* Analog Devices ADT7461
Prefix: 'adt7461'
Addresses scanned: I2C 0x4c and 0x4d
Datasheet: Publicly available at the ON Semiconductor website
https://www.onsemi.com/PowerSolutions/product.do?id=ADT7461
* Analog Devices ADT7461A
Prefix: 'adt7461a'
Addresses scanned: I2C 0x4c and 0x4d
Datasheet: Publicly available at the ON Semiconductor website
https://www.onsemi.com/PowerSolutions/product.do?id=ADT7461A
* Analog Devices ADT7481
Prefix: 'adt7481'
Addresses scanned: I2C 0x4b and 0x4c
Datasheet: Publicly available at the ON Semiconductor website
https://www.onsemi.com/PowerSolutions/product.do?id=ADT7481
* Analog Devices ADT7482
Prefix: 'adt7482'
Addresses scanned: I2C 0x4c
Datasheet: Publicly available at the ON Semiconductor website
https://www.onsemi.com/PowerSolutions/product.do?id=ADT7482
* Analog Devices ADT7483A
Prefix: 'adt7483a'
Addresses scanned: I2C 0x18, 0x19, 0x1a, 0x29, 0x2a, 0x2b, 0x4c, 0x4d, 0x4e
Datasheet: Publicly available at the ON Semiconductor website
https://www.onsemi.com/PowerSolutions/product.do?id=ADT7483A
* ON Semiconductor NCT1008
Prefix: 'nct1008'
Addresses scanned: I2C 0x4c and 0x4d
Datasheet: Publicly available at the ON Semiconductor website
https://www.onsemi.com/PowerSolutions/product.do?id=NCT1008
* ON Semiconductor NCT210
Prefix: 'adm1021'
Addresses scanned: I2C 0x18 - 0x1a, 0x29 - 0x2b, 0x4c - 0x4e
Datasheet: Publicly available at the ON Semiconductor website
https://www.onsemi.com/PowerSolutions/product.do?id=NCT210
* ON Semiconductor NCT214
Prefix: 'nct214'
Addresses scanned: I2C 0x18 - 0x1a, 0x29 - 0x2b, 0x4c - 0x4e
Datasheet: Publicly available at the ON Semiconductor website
https://www.onsemi.com/PowerSolutions/product.do?id=NCT214
* ON Semiconductor NCT218
Prefix: 'nct218'
Addresses scanned: I2C 0x4c - 0x4d
Datasheet: Publicly available at the ON Semiconductor website
https://www.onsemi.com/PowerSolutions/product.do?id=NCT218
* ON Semiconductor NCT72
Prefix: 'nct72'
Addresses scanned: I2C 0x4c - 0x4d
Datasheet: Publicly available at the ON Semiconductor website
https://www.onsemi.com/PowerSolutions/product.do?id=NCT72
* Maxim MAX1617
Prefix: 'max1617'
Addresses scanned: I2C 0x18 - 0x1a, 0x29 - 0x2b, 0x4c - 0x4e
Datasheet: Publicly available at the Maxim website
* Maxim MAX1617A
Prefix: 'max1617a'
Addresses scanned: I2C 0x18 - 0x1a, 0x29 - 0x2b, 0x4c - 0x4e
Datasheet: Publicly available at the Maxim website
* Maxim MAX6642
Prefix: 'max6642'
Addresses scanned: I2C 0x48-0x4f
Datasheet: Publicly available at the Maxim website
http://datasheets.maxim-ic.com/en/ds/MAX6642.pdf
* Maxim MAX6646
Prefix: 'max6646'
Addresses scanned: I2C 0x4d
Datasheet: Publicly available at the Maxim website
http://www.maxim-ic.com/quick_view2.cfm/qv_pk/3497
* Maxim MAX6647
Prefix: 'max6646'
Addresses scanned: I2C 0x4e
Datasheet: Publicly available at the Maxim website
http://www.maxim-ic.com/quick_view2.cfm/qv_pk/3497
* Maxim MAX6648
Prefix: 'max6648'
Addresses scanned: I2C 0x4c
Datasheet: Publicly available at the Maxim website
http://www.maxim-ic.com/quick_view2.cfm/qv_pk/3500
* Maxim MAX6649
Prefix: 'max6646'
Addresses scanned: I2C 0x4c
Datasheet: Publicly available at the Maxim website
http://www.maxim-ic.com/quick_view2.cfm/qv_pk/3497
* Maxim MAX6654
Prefix: 'max6654'
Addresses scanned: I2C 0x18, 0x19, 0x1a, 0x29, 0x2a, 0x2b,
0x4c, 0x4d and 0x4e
Datasheet: Publicly available at the Maxim website
https://www.maximintegrated.com/en/products/sensors/MAX6654.html
* Maxim MAX6657
Prefix: 'max6657'
Addresses scanned: I2C 0x4c
Datasheet: Publicly available at the Maxim website
http://www.maxim-ic.com/quick_view2.cfm/qv_pk/2578
* Maxim MAX6658
Prefix: 'max6657'
Addresses scanned: I2C 0x4c
Datasheet: Publicly available at the Maxim website
http://www.maxim-ic.com/quick_view2.cfm/qv_pk/2578
* Maxim MAX6659
Prefix: 'max6659'
Addresses scanned: I2C 0x4c, 0x4d, 0x4e
Datasheet: Publicly available at the Maxim website
http://www.maxim-ic.com/quick_view2.cfm/qv_pk/2578
* Maxim MAX6680
Prefix: 'max6680'
Addresses scanned: I2C 0x18, 0x19, 0x1a, 0x29, 0x2a, 0x2b,
0x4c, 0x4d and 0x4e
Datasheet: Publicly available at the Maxim website
http://www.maxim-ic.com/quick_view2.cfm/qv_pk/3370
* Maxim MAX6681
Prefix: 'max6680'
Addresses scanned: I2C 0x18, 0x19, 0x1a, 0x29, 0x2a, 0x2b,
0x4c, 0x4d and 0x4e
Datasheet: Publicly available at the Maxim website
http://www.maxim-ic.com/quick_view2.cfm/qv_pk/3370
* Maxim MAX6692
Prefix: 'max6648'
Addresses scanned: I2C 0x4c
Datasheet: Publicly available at the Maxim website
http://www.maxim-ic.com/quick_view2.cfm/qv_pk/3500
* Maxim MAX6695
Prefix: 'max6695'
Addresses scanned: I2C 0x18
Datasheet: Publicly available at the Maxim website
http://www.maxim-ic.com/datasheet/index.mvp/id/4199
* Maxim MAX6696
Prefix: 'max6695'
Addresses scanned: I2C 0x18, 0x19, 0x1a, 0x29, 0x2a, 0x2b,
0x4c, 0x4d and 0x4e
Datasheet: Publicly available at the Maxim website
http://www.maxim-ic.com/datasheet/index.mvp/id/4199
* Winbond/Nuvoton W83L771W/G
Prefix: 'w83l771'
Addresses scanned: I2C 0x4c
Datasheet: No longer available
* Winbond/Nuvoton W83L771AWG/ASG
Prefix: 'w83l771'
Addresses scanned: I2C 0x4c
Datasheet: Not publicly available, can be requested from Nuvoton
* Philips/NXP SA56004X
Prefix: 'sa56004'
Addresses scanned: I2C 0x48 through 0x4F
Datasheet: Publicly available at NXP website
http://ics.nxp.com/products/interface/datasheet/sa56004x.pdf
* GMT G781
Prefix: 'g781'
Addresses scanned: I2C 0x4c, 0x4d
Datasheet: Not publicly available from GMT
* Texas Instruments TMP451
Prefix: 'tmp451'
Addresses scanned: I2C 0x4c
Datasheet: Publicly available at TI website
https://www.ti.com/litv/pdf/sbos686
* Texas Instruments TMP461
Prefix: 'tmp461'
Addresses scanned: I2C 0x48 through 0x4F
Datasheet: Publicly available at TI website
https://www.ti.com/lit/gpn/tmp461
* Philips NE1617, NE1617A
Prefix: 'max1617' (probably detected as a max1617)
Addresses scanned: I2C 0x18 - 0x1a, 0x29 - 0x2b, 0x4c - 0x4e
Datasheets: Publicly available at the Philips website
* Philips NE1618
Prefix: 'ne1618'
Addresses scanned: I2C 0x18 - 0x1a, 0x29 - 0x2b, 0x4c - 0x4e
Datasheets: Publicly available at the Philips website
* Genesys Logic GL523SM
Prefix: 'gl523sm'
Addresses scanned: I2C 0x18 - 0x1a, 0x29 - 0x2b, 0x4c - 0x4e
Datasheet:
* TI THMC10
Prefix: 'thmc10'
Addresses scanned: I2C 0x18 - 0x1a, 0x29 - 0x2b, 0x4c - 0x4e
Datasheet: Publicly available at the TI website
* Onsemi MC1066
Prefix: 'mc1066'
Addresses scanned: I2C 0x18 - 0x1a, 0x29 - 0x2b, 0x4c - 0x4e
Datasheet: Publicly available at the Onsemi website
Author: Jean Delvare <jdelvare@suse.de>
Description
-----------
The LM90 is a digital temperature sensor. It senses its own temperature as
well as the temperature of up to one external diode. It is compatible
with many other devices, many of which are supported by this driver.
The family of chips supported by this driver is derived from MAX1617.
This chip as well as various compatible chips support a local and a remote
temperature sensor with 8 bit accuracy. Later chips provide improved accuracy
and other additional features such as hysteresis and temperature offset
registers.
Note that there is no easy way to differentiate between the MAX6657,
MAX6658 and MAX6659 variants. The extra features of the MAX6659 are only
supported by this driver if the chip is located at address 0x4d or 0x4e,
or if the chip type is explicitly selected as max6659.
The MAX6680 and MAX6681 only differ in their pinout, therefore they obviously
can't (and don't need to) be distinguished.
The different chipsets of the family are not strictly identical, although
very similar. For reference, here comes a non-exhaustive list of specific
features:
LM84:
* 8 bit sensor resolution
ADM1020, ADM1021, GL523SM, MAX1617, NE1617, NE1617A, THMC10:
* 8 bit sensor resolution
* Low temperature limits
NCT210, NE1618:
* 11 bit sensor resolution for remote temperature sensor
* Low temperature limits
ADM1021A, ADM1023:
* Temperature offset register for remote temperature sensor
* 11 bit resolution for remote temperature sensor
* Low temperature limits
LM90:
* 11 bit resolution for remote temperature sensor
* Temperature offset register for remote temperature sensor
* Low and critical temperature limits
* Configurable conversion rate
* Filter and alert configuration register at 0xBF.
* ALERT is triggered by temperatures over critical limits.
LM86 and LM89:
* Same as LM90
* Better external channel accuracy
LM99:
* Same as LM89
* External temperature shifted by 16 degrees down
ADM1032:
* Consecutive alert register at 0x22.
* Conversion averaging.
* Up to 64 conversions/s.
* ALERT is triggered by open remote sensor.
* SMBus PEC support for Write Byte and Receive Byte transactions.
ADT7461, ADT7461A, NCT1008:
* Extended temperature range (breaks compatibility)
* Lower resolution for remote temperature
* SMBus PEC support for Write Byte and Receive Byte transactions.
* 10 bit temperature resolution
ADT7481, ADT7482, ADT7483:
* Temperature offset register
* SMBus PEC support
* 10 bit temperature resolution for external sensors
* Two remote sensors
* Selectable address (ADT7483)
MAX6642:
* No critical limit register
* Conversion rate not configurable
* Better local resolution (10 bit)
* 10 bit external sensor resolution
MAX6646, MAX6647, MAX6649:
* Better local resolution
* Extended range unsigned external temperature
MAX6648, MAX6692:
* Better local resolution
* Unsigned temperature
MAX6654, MAX6690:
* Better local resolution
* Selectable address
* Remote sensor type selection
* Extended temperature range
* Extended resolution only available when conversion rate <= 1 Hz
MAX6657 and MAX6658:
* Better local resolution
* Remote sensor type selection
MAX6659:
* Better local resolution
* Selectable address
* Second critical temperature limit
* Remote sensor type selection
MAX6680 and MAX6681:
* Selectable address
* Remote sensor type selection
MAX6695 and MAX6696:
* Better local resolution
* Selectable address (max6696)
* Second critical temperature limit
* Two remote sensors
W83L771W/G
* The G variant is lead-free, otherwise similar to the W.
* Filter and alert configuration register at 0xBF
* Moving average (depending on conversion rate)
W83L771AWG/ASG
* Successor of the W83L771W/G, same features.
* The AWG and ASG variants only differ in package format.
* Diode ideality factor configuration (remote sensor) at 0xE3
SA56004X:
* Better local resolution
All temperature values are given in degrees Celsius. Resolution
is 1.0 degree for the local temperature, 0.125 degree for the remote
temperature, except for the MAX6654, MAX6657, MAX6658 and MAX6659 which have
a resolution of 0.125 degree for both temperatures.
Each sensor has its own high and low limits, plus a critical limit.
Additionally, there is a relative hysteresis value common to both critical
values. To make life easier to user-space applications, two absolute values
are exported, one for each channel, but these values are of course linked.
Only the local hysteresis can be set from user-space, and the same delta
applies to the remote hysteresis.
The lm90 driver will not update its values more frequently than configured with
the update_interval attribute; reading them more often will do no harm, but will
return 'old' values.
SMBus Alert Support
-------------------
This driver has basic support for SMBus alert. When an alert is received,
the status register is read and the faulty temperature channel is logged.
The Analog Devices chips (ADM1032, ADT7461 and ADT7461A) and ON
Semiconductor chips (NCT1008) do not implement the SMBus alert protocol
properly so additional care is needed: the ALERT output is disabled when
an alert is received, and is re-enabled only when the alarm is gone.
Otherwise the chip would block alerts from other chips in the bus as long
as the alarm is active.
PEC Support
-----------
The ADM1032 is the only chip of the family which supports PEC. It does
not support PEC on all transactions though, so some care must be taken.
When reading a register value, the PEC byte is computed and sent by the
ADM1032 chip. However, in the case of a combined transaction (SMBus Read
Byte), the ADM1032 computes the CRC value over only the second half of
the message rather than its entirety, because it thinks the first half
of the message belongs to a different transaction. As a result, the CRC
value differs from what the SMBus master expects, and all reads fail.
For this reason, the lm90 driver will enable PEC for the ADM1032 only if
the bus supports the SMBus Send Byte and Receive Byte transaction types.
These transactions will be used to read register values, instead of
SMBus Read Byte, and PEC will work properly.
Additionally, the ADM1032 doesn't support SMBus Send Byte with PEC.
Instead, it will try to write the PEC value to the register (because the
SMBus Send Byte transaction with PEC is similar to a Write Byte transaction
without PEC), which is not what we want. Thus, PEC is explicitly disabled
on SMBus Send Byte transactions in the lm90 driver.
PEC on byte data transactions represents a significant increase in bandwidth
usage (+33% for writes, +25% for reads) in normal conditions. With the need
to use two SMBus transaction for reads, this overhead jumps to +50%. Worse,
two transactions will typically mean twice as much delay waiting for
transaction completion, effectively doubling the register cache refresh time.
I guess reliability comes at a price, but it's quite expensive this time.
So, as not everyone might enjoy the slowdown, PEC is disabled by default and
can be enabled through sysfs. Just write 1 to the "pec" file and PEC will be
enabled. Write 0 to that file to disable PEC again.