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This is the hwmon driver for Microchip EMC1812/13/14/15/33 Multichannel Low-Voltage Remote Diode Sensor Family. EMC1812 has one external remote temperature monitoring channel. EMC1813 has two external remote temperature monitoring channels. EMC1814 has three external remote temperature monitoring channels, channels 2 and 3 support anti parallel diode. EMC1815 has four external remote temperature monitoring channels and channels 1/2 and 3/4 support anti parallel diode. EMC1833 has two external remote temperature monitoring channels and channels 1 and 2 support anti parallel diode. Resistance Error Correction is supported on channels 1/2 and 3/4. Signed-off-by: Marius Cristea <marius.cristea@microchip.com> Link: https://lore.kernel.org/r/20260610-hw_mon-emc1812-v11-2-cef809af5c19@microchip.com Signed-off-by: Guenter Roeck <linux@roeck-us.net>
68 lines
3.0 KiB
ReStructuredText
68 lines
3.0 KiB
ReStructuredText
.. SPDX-License-Identifier: GPL-2.0-or-later
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Kernel driver emc1812
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=====================
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Supported chips:
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* Microchip EMC1812, EMC1813, EMC1814, EMC1815, EMC1833
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Prefix: 'emc1812'
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Datasheets:
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- https://ww1.microchip.com/downloads/aemDocuments/documents/MSLD/ProductDocuments/DataSheets/EMC1812-3-4-5-33-Data-Sheet-DS20005751.pdf
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Author:
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Marius Cristea <marius.cristea@microchip.com>
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Description
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-----------
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The Microchip EMC181x/33 chips contain up to 4 remote temperature sensors
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and one internal.
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- The EMC1812 is a single channel remote temperature sensor.
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- The EMC1813 and EMC1833 are dual channel remote temperature sensor. The
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remote channels for this selection of devices can support substrate diodes,
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discrete diode-connected transistors or CPU/GPU thermal diodes.
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- The EMC1814 is a three channel remote temperature sensor that supports
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Anti-Parallel Diode (APD) only on one channel. For the channel that does not
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support APD functionality, substrate diodes, discrete diode-connected
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transistors or CPU/GPU thermal diodes are supported. For the channel that
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supports APD, only discrete diode-connected transistors may be implemented.
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However, if APD is disabled on the EMC1814, then the channel that supports
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APD will be functional with substrate diodes, discrete diode-connected
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transistors and CPU/GPU thermal diodes.
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- The EMC1815 is a four channel remote temperature sensor.
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The EMC1815 and EMC1833 support APD on all channels. When APD is enabled,
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the channels support only diode-connected transistors. If APD is disabled,
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then the channels will support substrate transistors, discrete diode-connected
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transistors and CPU/GPU thermal diodes.
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Note: Disabling APD functionality to implement substrate diodes on devices
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that support APD eliminates the benefit of APD (two diodes on one channel).
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The chips implement three limits for each sensor: low (tempX_min), high
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(tempX_max) and critical (tempX_crit). The chips also implement an
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hysteresis mechanism which applies to all limits. The relative difference
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is stored in a single register on the chip, which means that the relative
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difference between the limit and its hysteresis is always the same for
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all three limits.
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This implementation detail implies the following:
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* When setting a limit, its hysteresis will automatically follow, the
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difference staying unchanged. For example, if the old critical limit was
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80 degrees C, and the hysteresis was 75 degrees C, and you change the
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critical limit to 90 degrees C, then the hysteresis will automatically
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change to 85 degrees C.
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* The hysteresis values can't be set independently. We decided to make
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only tempX_crit_hyst writable, while all other hysteresis attributes
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are read-only. Setting tempX_crit_hyst writes the difference between
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tempX_crit_hyst and tempX_crit into the chip, and the same relative
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hysteresis applies automatically to all other limits.
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* The limits should be set before the hysteresis. At power up the device
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starts with 10 degree hysteresis.
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