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Diffstat (limited to 'kernel/Documentation/hwmon/jc42')
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diff --git a/kernel/Documentation/hwmon/jc42 b/kernel/Documentation/hwmon/jc42 new file mode 100644 index 000000000..f7f1830a2 --- /dev/null +++ b/kernel/Documentation/hwmon/jc42 @@ -0,0 +1,102 @@ +Kernel driver jc42 +================== + +Supported chips: + * Analog Devices ADT7408 + Datasheets: + http://www.analog.com/static/imported-files/data_sheets/ADT7408.pdf + * Atmel AT30TS00, AT30TS002A/B, AT30TSE004A + Datasheets: + http://www.atmel.com/Images/doc8585.pdf + http://www.atmel.com/Images/doc8711.pdf + http://www.atmel.com/Images/Atmel-8852-SEEPROM-AT30TSE002A-Datasheet.pdf + http://www.atmel.com/Images/Atmel-8868-DTS-AT30TSE004A-Datasheet.pdf + * IDT TSE2002B3, TSE2002GB2, TSE2004GB2, TS3000B3, TS3000GB0, TS3000GB2, + TS3001GB2 + Datasheets: + Available from IDT web site + * Maxim MAX6604 + Datasheets: + http://datasheets.maxim-ic.com/en/ds/MAX6604.pdf + * Microchip MCP9804, MCP9805, MCP98242, MCP98243, MCP98244, 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 + http://ww1.microchip.com/downloads/en/DeviceDoc/22327A.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, STTS2004, STTS3000 + Datasheets: + http://www.st.com/web/en/resource/technical/document/datasheet/CD00157556.pdf + http://www.st.com/web/en/resource/technical/document/datasheet/CD00157558.pdf + http://www.st.com/web/en/resource/technical/document/datasheet/CD00266638.pdf + http://www.st.com/web/en/resource/technical/document/datasheet/CD00225278.pdf + http://www.st.com/web/en/resource/technical/document/datasheet/DM00076709.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 <linux@roeck-us.net> + + +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 |