[linux-block.git] / Documentation / hwmon / jc42

Kernel driver jc42
==================

Supported chips:
  * Analog Devices ADT7408
    Prefix: 'adt7408'
    Addresses scanned: I2C 0x18 - 0x1f
    Datasheets:
	http://www.analog.com/static/imported-files/data_sheets/ADT7408.pdf
  * Atmel AT30TS00
    Prefix: 'at30ts00'
    Addresses scanned: I2C 0x18 - 0x1f
    Datasheets:
	http://www.atmel.com/Images/doc8585.pdf
  * IDT TSE2002B3, TSE2002GB2, TS3000B3, TS3000GB2
    Prefix: 'tse2002', 'ts3000'
    Addresses scanned: I2C 0x18 - 0x1f
    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
    Prefix: 'max6604'
    Addresses scanned: I2C 0x18 - 0x1f
    Datasheets:
	http://datasheets.maxim-ic.com/en/ds/MAX6604.pdf
  * Microchip MCP9804, MCP9805, MCP98242, MCP98243, MCP9843
    Prefixes: 'mcp9804', 'mcp9805', 'mcp98242', 'mcp98243', 'mcp9843'
    Addresses scanned: I2C 0x18 - 0x1f
    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
    Prefix: 'se97'
    Addresses scanned: I2C 0x18 - 0x1f
    Datasheets:
	http://www.nxp.com/documents/data_sheet/SE97.pdf
	http://www.nxp.com/documents/data_sheet/SE97B.pdf
  * NXP Semiconductors SE98
    Prefix: 'se98'
    Addresses scanned: I2C 0x18 - 0x1f
    Datasheets:
	http://www.nxp.com/documents/data_sheet/SE98.pdf
  * ON Semiconductor CAT34TS02, CAT6095
    Prefix: 'cat34ts02', 'cat6095'
    Addresses scanned: I2C 0x18 - 0x1f
    Datasheet:
	http://www.onsemi.com/pub_link/Collateral/CAT34TS02-D.PDF
	http://www.onsemi.com/pub/Collateral/CAT6095-D.PDF
  * ST Microelectronics STTS424, STTS424E02
    Prefix: 'stts424'
    Addresses scanned: I2C 0x18 - 0x1f
    Datasheets:
	http://www.st.com/stonline/products/literature/ds/13447/stts424.pdf
	http://www.st.com/stonline/products/literature/ds/13448/stts424e02.pdf
  * ST Microelectronics STTS2002, STTS3000
    Prefix: 'stts2002', 'stts3000'
    Addresses scanned: I2C 0x18 - 0x1f
    Datasheets:
	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
    Prefix: 'jc42'
    Addresses scanned: I2C 0x18 - 0x1f
    Datasheet:
	http://www.jedec.org/sites/default/files/docs/4_01_04R19.pdf

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
Commit	Line	Data
4453d736 GR	1	Kernel driver jc42
	2	==================
	3
	4	Supported chips:
	5	* Analog Devices ADT7408
	6	Prefix: 'adt7408'
	7	Addresses scanned: I2C 0x18 - 0x1f
	8	Datasheets:
	9	http://www.analog.com/static/imported-files/data_sheets/ADT7408.pdf
1bd612a2 GR	10	* Atmel AT30TS00
1bd612a2 GR	11	Prefix: 'at30ts00'
4453d736 GR	12	Addresses scanned: I2C 0x18 - 0x1f
4453d736 GR	13	Datasheets:
1bd612a2 GR	14	http://www.atmel.com/Images/doc8585.pdf
	15	* IDT TSE2002B3, TSE2002GB2, TS3000B3, TS3000GB2
	16	Prefix: 'tse2002', 'ts3000'
	17	Addresses scanned: I2C 0x18 - 0x1f
	18	Datasheets:
	19	http://www.idt.com/sites/default/files/documents/IDT_TSE2002B3C_DST_20100512_120303152056.pdf
	20	http://www.idt.com/sites/default/files/documents/IDT_TSE2002GB2A1_DST_20111107_120303145914.pdf
	21	http://www.idt.com/sites/default/files/documents/IDT_TS3000B3A_DST_20101129_120303152013.pdf
	22	http://www.idt.com/sites/default/files/documents/IDT_TS3000GB2A1_DST_20111104_120303151012.pdf
4453d736 GR	23	* Maxim MAX6604
	24	Prefix: 'max6604'
	25	Addresses scanned: I2C 0x18 - 0x1f
	26	Datasheets:
	27	http://datasheets.maxim-ic.com/en/ds/MAX6604.pdf
1bd612a2 GR	28	* Microchip MCP9804, MCP9805, MCP98242, MCP98243, MCP9843
1bd612a2 GR	29	Prefixes: 'mcp9804', 'mcp9805', 'mcp98242', 'mcp98243', 'mcp9843'
4453d736 GR	30	Addresses scanned: I2C 0x18 - 0x1f
4453d736 GR	31	Datasheets:
1bd612a2	32	http://ww1.microchip.com/downloads/en/DeviceDoc/22203C.pdf
4453d736 GR	33	http://ww1.microchip.com/downloads/en/DeviceDoc/21977b.pdf
	34	http://ww1.microchip.com/downloads/en/DeviceDoc/21996a.pdf
	35	http://ww1.microchip.com/downloads/en/DeviceDoc/22153c.pdf
	36	* NXP Semiconductors SE97, SE97B
	37	Prefix: 'se97'
	38	Addresses scanned: I2C 0x18 - 0x1f
	39	Datasheets:
	40	http://www.nxp.com/documents/data_sheet/SE97.pdf
	41	http://www.nxp.com/documents/data_sheet/SE97B.pdf
	42	* NXP Semiconductors SE98
	43	Prefix: 'se98'
	44	Addresses scanned: I2C 0x18 - 0x1f
	45	Datasheets:
	46	http://www.nxp.com/documents/data_sheet/SE98.pdf
	47	* ON Semiconductor CAT34TS02, CAT6095
	48	Prefix: 'cat34ts02', 'cat6095'
	49	Addresses scanned: I2C 0x18 - 0x1f
	50	Datasheet:
	51	http://www.onsemi.com/pub_link/Collateral/CAT34TS02-D.PDF
	52	http://www.onsemi.com/pub/Collateral/CAT6095-D.PDF
	53	* ST Microelectronics STTS424, STTS424E02
	54	Prefix: 'stts424'
	55	Addresses scanned: I2C 0x18 - 0x1f
	56	Datasheets:
	57	http://www.st.com/stonline/products/literature/ds/13447/stts424.pdf
	58	http://www.st.com/stonline/products/literature/ds/13448/stts424e02.pdf
4de86126 JD	59	* ST Microelectronics STTS2002, STTS3000
	60	Prefix: 'stts2002', 'stts3000'
	61	Addresses scanned: I2C 0x18 - 0x1f
	62	Datasheets:
	63	http://www.st.com/internet/com/TECHNICAL_RESOURCES/TECHNICAL_LITERATURE/DATASHEET/CD00225278.pdf
	64	http://www.st.com/internet/com/TECHNICAL_RESOURCES/TECHNICAL_LITERATURE/DATA_BRIEF/CD00270920.pdf
4453d736 GR	65	* JEDEC JC 42.4 compliant temperature sensor chips
	66	Prefix: 'jc42'
	67	Addresses scanned: I2C 0x18 - 0x1f
d5622f5b CL	68	Datasheet:
d5622f5b CL	69	http://www.jedec.org/sites/default/files/docs/4_01_04R19.pdf
4453d736 GR	70
	71	Author:
	72	Guenter Roeck <guenter.roeck@ericsson.com>
	73
	74
	75	Description
	76	-----------
	77
d5622f5b CL	78	This driver implements support for JEDEC JC 42.4 compliant temperature sensors,
	79	which are used on many DDR3 memory modules for mobile devices and servers. Some
	80	systems use the sensor to prevent memory overheating by automatically throttling
	81	the memory controller.
	82
4453d736 GR	83	The driver auto-detects the chips listed above, but can be manually instantiated
	84	to support other JC 42.4 compliant chips.
	85
	86	Example: the following will load the driver for a generic JC 42.4 compliant
	87	temperature sensor at address 0x18 on I2C bus #1:
	88
	89	# modprobe jc42
	90	# echo jc42 0x18 > /sys/bus/i2c/devices/i2c-1/new_device
	91
	92	A JC 42.4 compliant chip supports a single temperature sensor. Minimum, maximum,
	93	and critical temperature can be configured. There are alarms for high, low,
	94	and critical thresholds.
	95
	96	There is also an hysteresis to control the thresholds for resetting alarms.
	97	Per JC 42.4 specification, the hysteresis threshold can be configured to 0, 1.5,
	98	3.0, and 6.0 degrees C. Configured hysteresis values will be rounded to those
	99	limits. The chip supports only a single register to configure the hysteresis,
	100	which applies to all limits. This register can be written by writing into
	101	temp1_crit_hyst. Other hysteresis attributes are read-only.
	102
2c6315da CL	103	If the BIOS has configured the sensor for automatic temperature management, it
	104	is likely that it has locked the registers, i.e., that the temperature limits
	105	cannot be changed.
	106
4453d736 GR	107	Sysfs entries
	108	-------------
	109
	110	temp1_input Temperature (RO)
2c6315da CL	111	temp1_min Minimum temperature (RO or RW)
	112	temp1_max Maximum temperature (RO or RW)
	113	temp1_crit Critical high temperature (RO or RW)
4453d736	114
2c6315da	115	temp1_crit_hyst Critical hysteresis temperature (RO or RW)
4453d736 GR	116	temp1_max_hyst Maximum hysteresis temperature (RO)
	117
	118	temp1_min_alarm Temperature low alarm
	119	temp1_max_alarm Temperature high alarm
	120	temp1_crit_alarm Temperature critical alarm