mirror of
https://github.com/AuxXxilium/linux_dsm_epyc7002.git
synced 2024-11-26 01:00:58 +07:00
276 lines
11 KiB
Plaintext
276 lines
11 KiB
Plaintext
Kernel driver lm90
|
|
==================
|
|
|
|
Supported chips:
|
|
* 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 ADM1032
|
|
Prefix: 'adm1032'
|
|
Addresses scanned: I2C 0x4c and 0x4d
|
|
Datasheet: Publicly available at the ON Semiconductor website
|
|
http://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
|
|
http://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
|
|
http://www.onsemi.com/PowerSolutions/product.do?id=ADT7461A
|
|
* ON Semiconductor NCT1008
|
|
Prefix: 'nct1008'
|
|
Addresses scanned: I2C 0x4c and 0x4d
|
|
Datasheet: Publicly available at the ON Semiconductor website
|
|
http://www.onsemi.com/PowerSolutions/product.do?id=NCT1008
|
|
* 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: 'max6646'
|
|
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 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: 'max6646'
|
|
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
|
|
http://www.ti.com/litv/pdf/sbos686
|
|
|
|
|
|
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.
|
|
|
|
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 specificity of this family of chipsets over the ADM1021/LM84
|
|
family is that it features critical limits with hysteresis, and an
|
|
increased resolution of the remote temperature measurement.
|
|
|
|
The different chipsets of the family are not strictly identical, although
|
|
very similar. For reference, here comes a non-exhaustive list of specific
|
|
features:
|
|
|
|
LM90:
|
|
* 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
|
|
|
|
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 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 can be disabled through
|
|
sysfs. Just write 0 to the "pec" file and PEC will be disabled. Write 1
|
|
to that file to enable PEC again.
|