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84899d394e
All chips in this chip series only support a single hysteresis value. Having multiple writable hysteresis attributes is therefore confusing, since a single write affects all hysteresis temperatures. Make all but one (temp1_crit_hyst) read-only. Reviewed-by: Jean Delvare <jdelvare@suse.de> Signed-off-by: Guenter Roeck <linux@roeck-us.net>
60 lines
2.4 KiB
Plaintext
60 lines
2.4 KiB
Plaintext
Kernel driver emc1403
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=====================
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Supported chips:
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* SMSC / Microchip EMC1402, EMC1412
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Addresses scanned: I2C 0x18, 0x1c, 0x29, 0x4c, 0x4d, 0x5c
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Prefix: 'emc1402'
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Datasheets:
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http://ww1.microchip.com/downloads/en/DeviceDoc/1412.pdf
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http://ww1.microchip.com/downloads/en/DeviceDoc/1402.pdf
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* SMSC / Microchip EMC1403, EMC1404, EMC1413, EMC1414
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Addresses scanned: I2C 0x18, 0x29, 0x4c, 0x4d
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Prefix: 'emc1403', 'emc1404'
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Datasheets:
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http://ww1.microchip.com/downloads/en/DeviceDoc/1403_1404.pdf
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http://ww1.microchip.com/downloads/en/DeviceDoc/1413_1414.pdf
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* SMSC / Microchip EMC1422
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Addresses scanned: I2C 0x4c
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Prefix: 'emc1422'
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Datasheet:
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http://ww1.microchip.com/downloads/en/DeviceDoc/1422.pdf
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* SMSC / Microchip EMC1423, EMC1424
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Addresses scanned: I2C 0x4c
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Prefix: 'emc1423', 'emc1424'
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Datasheet:
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http://ww1.microchip.com/downloads/en/DeviceDoc/1423_1424.pdf
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Author:
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Kalhan Trisal <kalhan.trisal@intel.com
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Description
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-----------
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The Standard Microsystems Corporation (SMSC) / Microchip EMC14xx chips
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contain up to four temperature sensors. EMC14x2 support two sensors
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(one internal, one external). EMC14x3 support three sensors (one internal,
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two external), and EMC14x4 support four sensors (one internal, three
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external).
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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
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was 80 degrees C, and the hysteresis was 75 degrees C, and you change
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the critical limit to 90 degrees C, then the hysteresis will
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automatically 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 temp1_crit_hyst writable, while all other hysteresis attributes
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are read-only. Setting temp1_crit_hyst writes the difference between
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temp1_crit_hyst and temp1_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.
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