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authorDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-27 10:05:51 +0000
committerDaniel Baumann <daniel.baumann@progress-linux.org>2024-04-27 10:05:51 +0000
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+Kernel driver adm1021
+=====================
+
+Supported chips:
+
+ * 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
+
+ * Genesys Logic GL523SM
+
+ Prefix: 'gl523sm'
+
+ Addresses scanned: I2C 0x18 - 0x1a, 0x29 - 0x2b, 0x4c - 0x4e
+
+ Datasheet:
+
+ * 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
+
+ * National Semiconductor LM84
+
+ Prefix: 'lm84'
+
+ Addresses scanned: I2C 0x18 - 0x1a, 0x29 - 0x2b, 0x4c - 0x4e
+
+ Datasheet: Publicly available at the National Semiconductor website
+
+ * Philips NE1617
+
+ Prefix: 'max1617' (probably detected as a max1617)
+
+ Addresses scanned: I2C 0x18 - 0x1a, 0x29 - 0x2b, 0x4c - 0x4e
+
+ Datasheet: Publicly available at the Philips website
+
+ * Philips NE1617A
+
+ Prefix: 'max1617' (probably detected as a max1617)
+
+ Addresses scanned: I2C 0x18 - 0x1a, 0x29 - 0x2b, 0x4c - 0x4e
+
+ Datasheet: Publicly available at the Philips website
+
+ * 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
+
+
+Authors:
+ - Frodo Looijaard <frodol@dds.nl>,
+ - Philip Edelbrock <phil@netroedge.com>
+
+Module Parameters
+-----------------
+
+* read_only: int
+ Don't set any values, read only mode
+
+
+Description
+-----------
+
+The chips supported by this driver are very similar. The Maxim MAX1617 is
+the oldest; it has the problem that it is not very well detectable. The
+MAX1617A solves that. The ADM1021 is a straight clone of the MAX1617A.
+Ditto for the THMC10. From here on, we will refer to all these chips as
+ADM1021-clones.
+
+The ADM1021 and MAX1617A reports a die code, which is a sort of revision
+code. This can help us pinpoint problems; it is not very useful
+otherwise.
+
+ADM1021-clones implement two temperature sensors. One of them is internal,
+and measures the temperature of the chip itself; the other is external and
+is realised in the form of a transistor-like device. A special alarm
+indicates whether the remote sensor is connected.
+
+Each sensor has its own low and high limits. When they are crossed, the
+corresponding alarm is set and remains on as long as the temperature stays
+out of range. Temperatures are measured in degrees Celsius. Measurements
+are possible between -65 and +127 degrees, with a resolution of one degree.
+
+If an alarm triggers, it will remain triggered until the hardware register
+is read at least once. This means that the cause for the alarm may already
+have disappeared!
+
+This driver only updates its values each 1.5 seconds; reading it more often
+will do no harm, but will return 'old' values. It is possible to make
+ADM1021-clones do faster measurements, but there is really no good reason
+for that.
+
+
+Netburst-based Xeon support
+---------------------------
+
+Some Xeon processors based on the Netburst (early Pentium 4, from 2001 to
+2003) microarchitecture had real MAX1617, ADM1021, or compatible chips
+within them, with two temperature sensors. Other Xeon processors of this
+era (with 400 MHz FSB) had chips with only one temperature sensor.
+
+If you have such an old Xeon, and you get two valid temperatures when
+loading the adm1021 module, then things are good.
+
+If nothing happens when loading the adm1021 module, and you are certain
+that your specific Xeon processor model includes compatible sensors, you
+will have to explicitly instantiate the sensor chips from user-space. See
+method 4 in Documentation/i2c/instantiating-devices.rst. Possible slave
+addresses are 0x18, 0x1a, 0x29, 0x2b, 0x4c, or 0x4e. It is likely that
+only temp2 will be correct and temp1 will have to be ignored.
+
+Previous generations of the Xeon processor (based on Pentium II/III)
+didn't have these sensors. Next generations of Xeon processors (533 MHz
+FSB and faster) lost them, until the Core-based generation which
+introduced integrated digital thermal sensors. These are supported by
+the coretemp driver.