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Guenter Roeck4453d732010-08-09 17:21:08 -07001Kernel driver jc42
2==================
3
4Supported chips:
5 * Analog Devices ADT7408
Guenter Roeck4453d732010-08-09 17:21:08 -07006 Datasheets:
7 http://www.analog.com/static/imported-files/data_sheets/ADT7408.pdf
Guenter Roeck1bd612a2012-03-05 11:13:52 -08008 * Atmel AT30TS00
Guenter Roeck4453d732010-08-09 17:21:08 -07009 Datasheets:
Guenter Roeck1bd612a2012-03-05 11:13:52 -080010 http://www.atmel.com/Images/doc8585.pdf
11 * IDT TSE2002B3, TSE2002GB2, TS3000B3, TS3000GB2
Guenter Roeck1bd612a2012-03-05 11:13:52 -080012 Datasheets:
13 http://www.idt.com/sites/default/files/documents/IDT_TSE2002B3C_DST_20100512_120303152056.pdf
14 http://www.idt.com/sites/default/files/documents/IDT_TSE2002GB2A1_DST_20111107_120303145914.pdf
15 http://www.idt.com/sites/default/files/documents/IDT_TS3000B3A_DST_20101129_120303152013.pdf
16 http://www.idt.com/sites/default/files/documents/IDT_TS3000GB2A1_DST_20111104_120303151012.pdf
Guenter Roeck4453d732010-08-09 17:21:08 -070017 * Maxim MAX6604
Guenter Roeck4453d732010-08-09 17:21:08 -070018 Datasheets:
19 http://datasheets.maxim-ic.com/en/ds/MAX6604.pdf
Guenter Roeck1bd612a2012-03-05 11:13:52 -080020 * Microchip MCP9804, MCP9805, MCP98242, MCP98243, MCP9843
Guenter Roeck4453d732010-08-09 17:21:08 -070021 Datasheets:
Guenter Roeck1bd612a2012-03-05 11:13:52 -080022 http://ww1.microchip.com/downloads/en/DeviceDoc/22203C.pdf
Guenter Roeck4453d732010-08-09 17:21:08 -070023 http://ww1.microchip.com/downloads/en/DeviceDoc/21977b.pdf
24 http://ww1.microchip.com/downloads/en/DeviceDoc/21996a.pdf
25 http://ww1.microchip.com/downloads/en/DeviceDoc/22153c.pdf
Guenter Roeck86dda172012-03-08 08:20:24 -080026 * NXP Semiconductors SE97, SE97B, SE98, SE98A
Guenter Roeck4453d732010-08-09 17:21:08 -070027 Datasheets:
28 http://www.nxp.com/documents/data_sheet/SE97.pdf
29 http://www.nxp.com/documents/data_sheet/SE97B.pdf
Guenter Roeck4453d732010-08-09 17:21:08 -070030 http://www.nxp.com/documents/data_sheet/SE98.pdf
Guenter Roeck86dda172012-03-08 08:20:24 -080031 http://www.nxp.com/documents/data_sheet/SE98A.pdf
Guenter Roeck4453d732010-08-09 17:21:08 -070032 * ON Semiconductor CAT34TS02, CAT6095
Guenter Roeck4453d732010-08-09 17:21:08 -070033 Datasheet:
34 http://www.onsemi.com/pub_link/Collateral/CAT34TS02-D.PDF
35 http://www.onsemi.com/pub/Collateral/CAT6095-D.PDF
Guenter Roeck86dda172012-03-08 08:20:24 -080036 * ST Microelectronics STTS424, STTS424E02, STTS2002, STTS3000
Guenter Roeck4453d732010-08-09 17:21:08 -070037 Datasheets:
Guenter Roeck86dda172012-03-08 08:20:24 -080038 http://www.st.com/internet/com/TECHNICAL_RESOURCES/TECHNICAL_LITERATURE/DATASHEET/CD00157556.pdf
39 http://www.st.com/internet/com/TECHNICAL_RESOURCES/TECHNICAL_LITERATURE/DATASHEET/CD00157558.pdf
Jean Delvare4de86122012-03-05 08:32:00 -050040 http://www.st.com/internet/com/TECHNICAL_RESOURCES/TECHNICAL_LITERATURE/DATASHEET/CD00225278.pdf
41 http://www.st.com/internet/com/TECHNICAL_RESOURCES/TECHNICAL_LITERATURE/DATA_BRIEF/CD00270920.pdf
Guenter Roeck4453d732010-08-09 17:21:08 -070042 * JEDEC JC 42.4 compliant temperature sensor chips
Clemens Ladischd5622f52011-02-16 08:02:08 -050043 Datasheet:
44 http://www.jedec.org/sites/default/files/docs/4_01_04R19.pdf
Guenter Roeck4453d732010-08-09 17:21:08 -070045
Guenter Roeck86dda172012-03-08 08:20:24 -080046 Common for all chips:
47 Prefix: 'jc42'
48 Addresses scanned: I2C 0x18 - 0x1f
49
Guenter Roeck4453d732010-08-09 17:21:08 -070050Author:
51 Guenter Roeck <guenter.roeck@ericsson.com>
52
53
54Description
55-----------
56
Clemens Ladischd5622f52011-02-16 08:02:08 -050057This driver implements support for JEDEC JC 42.4 compliant temperature sensors,
58which are used on many DDR3 memory modules for mobile devices and servers. Some
59systems use the sensor to prevent memory overheating by automatically throttling
60the memory controller.
61
Guenter Roeck4453d732010-08-09 17:21:08 -070062The driver auto-detects the chips listed above, but can be manually instantiated
63to support other JC 42.4 compliant chips.
64
65Example: the following will load the driver for a generic JC 42.4 compliant
66temperature sensor at address 0x18 on I2C bus #1:
67
68# modprobe jc42
69# echo jc42 0x18 > /sys/bus/i2c/devices/i2c-1/new_device
70
71A JC 42.4 compliant chip supports a single temperature sensor. Minimum, maximum,
72and critical temperature can be configured. There are alarms for high, low,
73and critical thresholds.
74
75There is also an hysteresis to control the thresholds for resetting alarms.
76Per JC 42.4 specification, the hysteresis threshold can be configured to 0, 1.5,
773.0, and 6.0 degrees C. Configured hysteresis values will be rounded to those
78limits. The chip supports only a single register to configure the hysteresis,
79which applies to all limits. This register can be written by writing into
80temp1_crit_hyst. Other hysteresis attributes are read-only.
81
Clemens Ladisch2c6315d2011-02-16 08:02:38 -050082If the BIOS has configured the sensor for automatic temperature management, it
83is likely that it has locked the registers, i.e., that the temperature limits
84cannot be changed.
85
Guenter Roeck4453d732010-08-09 17:21:08 -070086Sysfs entries
87-------------
88
89temp1_input Temperature (RO)
Clemens Ladisch2c6315d2011-02-16 08:02:38 -050090temp1_min Minimum temperature (RO or RW)
91temp1_max Maximum temperature (RO or RW)
92temp1_crit Critical high temperature (RO or RW)
Guenter Roeck4453d732010-08-09 17:21:08 -070093
Clemens Ladisch2c6315d2011-02-16 08:02:38 -050094temp1_crit_hyst Critical hysteresis temperature (RO or RW)
Guenter Roeck4453d732010-08-09 17:21:08 -070095temp1_max_hyst Maximum hysteresis temperature (RO)
96
97temp1_min_alarm Temperature low alarm
98temp1_max_alarm Temperature high alarm
99temp1_crit_alarm Temperature critical alarm