hwmon: (adm1021) Clarify documentation regarding Xeon processors

    Prefix: 'gl523sm'

    Addresses scanned: I2C 0x18 - 0x1a, 0x29 - 0x2b, 0x4c - 0x4e

    Datasheet:

  * Intel Xeon Processor

    Prefix: - any other - may require 'force_adm1021' parameter

    Addresses scanned: none

    Datasheet: Publicly available at Intel website

  * Maxim MAX1617

    Prefix: 'max1617'

    Addresses scanned: I2C 0x18 - 0x1a, 0x29 - 0x2b, 0x4c - 0x4e

ADM1021-clones do faster measurements, but there is really no good reason

for that.

Xeon support

------------

Some Xeon processors have real max1617, adm1021, or compatible chips

within them, with two temperature sensors.

Netburst-based Xeon support

---------------------------

Other Xeons have chips with only one sensor.

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 a Xeon, and the adm1021 module loads, and both temperatures

appear valid, then things are good.

If you have such an old Xeon, and you get two valid temperatures when

loading the adm1021 module, then things are good.

If the adm1021 module doesn't load, you should try this:

	modprobe adm1021 force_adm1021=BUS,ADDRESS

	ADDRESS can only be 0x18, 0x1a, 0x29, 0x2b, 0x4c, or 0x4e.

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. 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.

If you have dual Xeons you may have appear to have two separate

adm1021-compatible chips, or two single-temperature sensors, at distinct

addresses.

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.

	help

	  If you say yes here you get support for Analog Devices ADM1021

	  and ADM1023 sensor chips and clones: Maxim MAX1617 and MAX1617A,

	  Genesys Logic GL523SM, National Semiconductor LM84, TI THMC10,

	  and the XEON processor built-in sensor.

	  Genesys Logic GL523SM, National Semiconductor LM84 and TI THMC10.

	  This driver can also be built as a module.  If so, the module

	  will be called adm1021.