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author | Srikant Patnaik | 2015-01-13 15:08:24 +0530 |
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committer | Srikant Patnaik | 2015-01-13 15:08:24 +0530 |
commit | 97327692361306d1e6259021bc425e32832fdb50 (patch) | |
tree | fe9088f3248ec61e24f404f21b9793cb644b7f01 /Documentation/hwmon/jc42 | |
parent | 2d05a8f663478a44e088d122e0d62109bbc801d0 (diff) | |
parent | a3a8b90b61e21be3dde9101c4e86c881e0f06210 (diff) | |
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diff --git a/Documentation/hwmon/jc42 b/Documentation/hwmon/jc42 new file mode 100644 index 00000000..66ecb9fc --- /dev/null +++ b/Documentation/hwmon/jc42 @@ -0,0 +1,99 @@ +Kernel driver jc42 +================== + +Supported chips: + * Analog Devices ADT7408 + Datasheets: + http://www.analog.com/static/imported-files/data_sheets/ADT7408.pdf + * Atmel AT30TS00 + Datasheets: + http://www.atmel.com/Images/doc8585.pdf + * IDT TSE2002B3, TSE2002GB2, TS3000B3, TS3000GB2 + Datasheets: + http://www.idt.com/sites/default/files/documents/IDT_TSE2002B3C_DST_20100512_120303152056.pdf + http://www.idt.com/sites/default/files/documents/IDT_TSE2002GB2A1_DST_20111107_120303145914.pdf + http://www.idt.com/sites/default/files/documents/IDT_TS3000B3A_DST_20101129_120303152013.pdf + http://www.idt.com/sites/default/files/documents/IDT_TS3000GB2A1_DST_20111104_120303151012.pdf + * Maxim MAX6604 + Datasheets: + http://datasheets.maxim-ic.com/en/ds/MAX6604.pdf + * Microchip MCP9804, MCP9805, MCP98242, MCP98243, MCP9843 + Datasheets: + http://ww1.microchip.com/downloads/en/DeviceDoc/22203C.pdf + http://ww1.microchip.com/downloads/en/DeviceDoc/21977b.pdf + http://ww1.microchip.com/downloads/en/DeviceDoc/21996a.pdf + http://ww1.microchip.com/downloads/en/DeviceDoc/22153c.pdf + * NXP Semiconductors SE97, SE97B, SE98, SE98A + Datasheets: + http://www.nxp.com/documents/data_sheet/SE97.pdf + http://www.nxp.com/documents/data_sheet/SE97B.pdf + http://www.nxp.com/documents/data_sheet/SE98.pdf + http://www.nxp.com/documents/data_sheet/SE98A.pdf + * ON Semiconductor CAT34TS02, CAT6095 + Datasheet: + http://www.onsemi.com/pub_link/Collateral/CAT34TS02-D.PDF + http://www.onsemi.com/pub/Collateral/CAT6095-D.PDF + * ST Microelectronics STTS424, STTS424E02, STTS2002, STTS3000 + Datasheets: + http://www.st.com/internet/com/TECHNICAL_RESOURCES/TECHNICAL_LITERATURE/DATASHEET/CD00157556.pdf + http://www.st.com/internet/com/TECHNICAL_RESOURCES/TECHNICAL_LITERATURE/DATASHEET/CD00157558.pdf + http://www.st.com/internet/com/TECHNICAL_RESOURCES/TECHNICAL_LITERATURE/DATASHEET/CD00225278.pdf + http://www.st.com/internet/com/TECHNICAL_RESOURCES/TECHNICAL_LITERATURE/DATA_BRIEF/CD00270920.pdf + * JEDEC JC 42.4 compliant temperature sensor chips + Datasheet: + http://www.jedec.org/sites/default/files/docs/4_01_04R19.pdf + + Common for all chips: + Prefix: 'jc42' + Addresses scanned: I2C 0x18 - 0x1f + +Author: + Guenter Roeck <guenter.roeck@ericsson.com> + + +Description +----------- + +This driver implements support for JEDEC JC 42.4 compliant temperature sensors, +which are used on many DDR3 memory modules for mobile devices and servers. Some +systems use the sensor to prevent memory overheating by automatically throttling +the memory controller. + +The driver auto-detects the chips listed above, but can be manually instantiated +to support other JC 42.4 compliant chips. + +Example: the following will load the driver for a generic JC 42.4 compliant +temperature sensor at address 0x18 on I2C bus #1: + +# modprobe jc42 +# echo jc42 0x18 > /sys/bus/i2c/devices/i2c-1/new_device + +A JC 42.4 compliant chip supports a single temperature sensor. Minimum, maximum, +and critical temperature can be configured. There are alarms for high, low, +and critical thresholds. + +There is also an hysteresis to control the thresholds for resetting alarms. +Per JC 42.4 specification, the hysteresis threshold can be configured to 0, 1.5, +3.0, and 6.0 degrees C. Configured hysteresis values will be rounded to those +limits. The chip supports only a single register to configure the hysteresis, +which applies to all limits. This register can be written by writing into +temp1_crit_hyst. Other hysteresis attributes are read-only. + +If the BIOS has configured the sensor for automatic temperature management, it +is likely that it has locked the registers, i.e., that the temperature limits +cannot be changed. + +Sysfs entries +------------- + +temp1_input Temperature (RO) +temp1_min Minimum temperature (RO or RW) +temp1_max Maximum temperature (RO or RW) +temp1_crit Critical high temperature (RO or RW) + +temp1_crit_hyst Critical hysteresis temperature (RO or RW) +temp1_max_hyst Maximum hysteresis temperature (RO) + +temp1_min_alarm Temperature low alarm +temp1_max_alarm Temperature high alarm +temp1_crit_alarm Temperature critical alarm |