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ccf988b66d
Convert each file at I2C subsystem, renaming them to .rst and adding to the driver-api book. Signed-off-by: Mauro Carvalho Chehab <mchehab+samsung@kernel.org> Acked-by: Wolfram Sang <wsa@the-dreams.de> Acked-by: Alexandre Belloni <alexandre.belloni@bootlin.com> Acked-by: Jonathan Cameron <Jonathan.Cameron@huawei.com> Signed-off-by: Jonathan Corbet <corbet@lwn.net>
154 lines
4.5 KiB
ReStructuredText
154 lines
4.5 KiB
ReStructuredText
Kernel driver adm1021
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=====================
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Supported chips:
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* Analog Devices ADM1021
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Prefix: 'adm1021'
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Addresses scanned: I2C 0x18 - 0x1a, 0x29 - 0x2b, 0x4c - 0x4e
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Datasheet: Publicly available at the Analog Devices website
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* Analog Devices ADM1021A/ADM1023
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Prefix: 'adm1023'
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Addresses scanned: I2C 0x18 - 0x1a, 0x29 - 0x2b, 0x4c - 0x4e
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Datasheet: Publicly available at the Analog Devices website
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* Genesys Logic GL523SM
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Prefix: 'gl523sm'
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Addresses scanned: I2C 0x18 - 0x1a, 0x29 - 0x2b, 0x4c - 0x4e
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Datasheet:
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* Maxim MAX1617
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Prefix: 'max1617'
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Addresses scanned: I2C 0x18 - 0x1a, 0x29 - 0x2b, 0x4c - 0x4e
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Datasheet: Publicly available at the Maxim website
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* Maxim MAX1617A
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Prefix: 'max1617a'
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Addresses scanned: I2C 0x18 - 0x1a, 0x29 - 0x2b, 0x4c - 0x4e
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Datasheet: Publicly available at the Maxim website
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* National Semiconductor LM84
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Prefix: 'lm84'
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Addresses scanned: I2C 0x18 - 0x1a, 0x29 - 0x2b, 0x4c - 0x4e
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Datasheet: Publicly available at the National Semiconductor website
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* Philips NE1617
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Prefix: 'max1617' (probably detected as a max1617)
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Addresses scanned: I2C 0x18 - 0x1a, 0x29 - 0x2b, 0x4c - 0x4e
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Datasheet: Publicly available at the Philips website
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* Philips NE1617A
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Prefix: 'max1617' (probably detected as a max1617)
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Addresses scanned: I2C 0x18 - 0x1a, 0x29 - 0x2b, 0x4c - 0x4e
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Datasheet: Publicly available at the Philips website
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* TI THMC10
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Prefix: 'thmc10'
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Addresses scanned: I2C 0x18 - 0x1a, 0x29 - 0x2b, 0x4c - 0x4e
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Datasheet: Publicly available at the TI website
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* Onsemi MC1066
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Prefix: 'mc1066'
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Addresses scanned: I2C 0x18 - 0x1a, 0x29 - 0x2b, 0x4c - 0x4e
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Datasheet: Publicly available at the Onsemi website
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Authors:
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- Frodo Looijaard <frodol@dds.nl>,
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- Philip Edelbrock <phil@netroedge.com>
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Module Parameters
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-----------------
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* read_only: int
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Don't set any values, read only mode
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Description
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-----------
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The chips supported by this driver are very similar. The Maxim MAX1617 is
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the oldest; it has the problem that it is not very well detectable. The
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MAX1617A solves that. The ADM1021 is a straight clone of the MAX1617A.
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Ditto for the THMC10. From here on, we will refer to all these chips as
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ADM1021-clones.
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The ADM1021 and MAX1617A reports a die code, which is a sort of revision
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code. This can help us pinpoint problems; it is not very useful
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otherwise.
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ADM1021-clones implement two temperature sensors. One of them is internal,
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and measures the temperature of the chip itself; the other is external and
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is realised in the form of a transistor-like device. A special alarm
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indicates whether the remote sensor is connected.
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Each sensor has its own low and high limits. When they are crossed, the
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corresponding alarm is set and remains on as long as the temperature stays
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out of range. Temperatures are measured in degrees Celsius. Measurements
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are possible between -65 and +127 degrees, with a resolution of one degree.
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If an alarm triggers, it will remain triggered until the hardware register
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is read at least once. This means that the cause for the alarm may already
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have disappeared!
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This driver only updates its values each 1.5 seconds; reading it more often
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will do no harm, but will return 'old' values. It is possible to make
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ADM1021-clones do faster measurements, but there is really no good reason
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for that.
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Netburst-based Xeon support
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---------------------------
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Some Xeon processors based on the Netburst (early Pentium 4, from 2001 to
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2003) microarchitecture had real MAX1617, ADM1021, or compatible chips
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within them, with two temperature sensors. Other Xeon processors of this
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era (with 400 MHz FSB) had chips with only one temperature sensor.
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If you have such an old Xeon, and you get two valid temperatures when
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loading the adm1021 module, then things are good.
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If nothing happens when loading the adm1021 module, and you are certain
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that your specific Xeon processor model includes compatible sensors, you
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will have to explicitly instantiate the sensor chips from user-space. See
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method 4 in Documentation/i2c/instantiating-devices.rst. Possible slave
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addresses are 0x18, 0x1a, 0x29, 0x2b, 0x4c, or 0x4e. It is likely that
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only temp2 will be correct and temp1 will have to be ignored.
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Previous generations of the Xeon processor (based on Pentium II/III)
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didn't have these sensors. Next generations of Xeon processors (533 MHz
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FSB and faster) lost them, until the Core-based generation which
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introduced integrated digital thermal sensors. These are supported by
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the coretemp driver.
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