| Guenter Roeck | 4453d73 | 2010-08-09 17:21:08 -0700 | [diff] [blame] | 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 |
| 10 | * IDT TSE2002B3, TS3000B3 |
| 11 | Prefix: 'tse2002b3', 'ts3000b3' |
| 12 | Addresses scanned: I2C 0x18 - 0x1f |
| 13 | Datasheets: |
| 14 | http://www.idt.com/products/getdoc.cfm?docid=18715691 |
| 15 | http://www.idt.com/products/getdoc.cfm?docid=18715692 |
| 16 | * Maxim MAX6604 |
| 17 | Prefix: 'max6604' |
| 18 | Addresses scanned: I2C 0x18 - 0x1f |
| 19 | Datasheets: |
| 20 | http://datasheets.maxim-ic.com/en/ds/MAX6604.pdf |
| 21 | * Microchip MCP9805, MCP98242, MCP98243, MCP9843 |
| 22 | Prefixes: 'mcp9805', 'mcp98242', 'mcp98243', 'mcp9843' |
| 23 | Addresses scanned: I2C 0x18 - 0x1f |
| 24 | Datasheets: |
| 25 | http://ww1.microchip.com/downloads/en/DeviceDoc/21977b.pdf |
| 26 | http://ww1.microchip.com/downloads/en/DeviceDoc/21996a.pdf |
| 27 | http://ww1.microchip.com/downloads/en/DeviceDoc/22153c.pdf |
| 28 | * NXP Semiconductors SE97, SE97B |
| 29 | Prefix: 'se97' |
| 30 | Addresses scanned: I2C 0x18 - 0x1f |
| 31 | Datasheets: |
| 32 | http://www.nxp.com/documents/data_sheet/SE97.pdf |
| 33 | http://www.nxp.com/documents/data_sheet/SE97B.pdf |
| 34 | * NXP Semiconductors SE98 |
| 35 | Prefix: 'se98' |
| 36 | Addresses scanned: I2C 0x18 - 0x1f |
| 37 | Datasheets: |
| 38 | http://www.nxp.com/documents/data_sheet/SE98.pdf |
| 39 | * ON Semiconductor CAT34TS02, CAT6095 |
| 40 | Prefix: 'cat34ts02', 'cat6095' |
| 41 | Addresses scanned: I2C 0x18 - 0x1f |
| 42 | Datasheet: |
| 43 | http://www.onsemi.com/pub_link/Collateral/CAT34TS02-D.PDF |
| 44 | http://www.onsemi.com/pub/Collateral/CAT6095-D.PDF |
| 45 | * ST Microelectronics STTS424, STTS424E02 |
| 46 | Prefix: 'stts424' |
| 47 | Addresses scanned: I2C 0x18 - 0x1f |
| 48 | Datasheets: |
| 49 | http://www.st.com/stonline/products/literature/ds/13447/stts424.pdf |
| 50 | http://www.st.com/stonline/products/literature/ds/13448/stts424e02.pdf |
| 51 | * JEDEC JC 42.4 compliant temperature sensor chips |
| 52 | Prefix: 'jc42' |
| 53 | Addresses scanned: I2C 0x18 - 0x1f |
| Clemens Ladisch | d5622f5 | 2011-02-16 08:02:08 -0500 | [diff] [blame] | 54 | Datasheet: |
| 55 | http://www.jedec.org/sites/default/files/docs/4_01_04R19.pdf |
| Guenter Roeck | 4453d73 | 2010-08-09 17:21:08 -0700 | [diff] [blame] | 56 | |
| 57 | Author: |
| 58 | Guenter Roeck <guenter.roeck@ericsson.com> |
| 59 | |
| 60 | |
| 61 | Description |
| 62 | ----------- |
| 63 | |
| Clemens Ladisch | d5622f5 | 2011-02-16 08:02:08 -0500 | [diff] [blame] | 64 | This driver implements support for JEDEC JC 42.4 compliant temperature sensors, |
| 65 | which are used on many DDR3 memory modules for mobile devices and servers. Some |
| 66 | systems use the sensor to prevent memory overheating by automatically throttling |
| 67 | the memory controller. |
| 68 | |
| Guenter Roeck | 4453d73 | 2010-08-09 17:21:08 -0700 | [diff] [blame] | 69 | The driver auto-detects the chips listed above, but can be manually instantiated |
| 70 | to support other JC 42.4 compliant chips. |
| 71 | |
| 72 | Example: the following will load the driver for a generic JC 42.4 compliant |
| 73 | temperature sensor at address 0x18 on I2C bus #1: |
| 74 | |
| 75 | # modprobe jc42 |
| 76 | # echo jc42 0x18 > /sys/bus/i2c/devices/i2c-1/new_device |
| 77 | |
| 78 | A JC 42.4 compliant chip supports a single temperature sensor. Minimum, maximum, |
| 79 | and critical temperature can be configured. There are alarms for high, low, |
| 80 | and critical thresholds. |
| 81 | |
| 82 | There is also an hysteresis to control the thresholds for resetting alarms. |
| 83 | Per JC 42.4 specification, the hysteresis threshold can be configured to 0, 1.5, |
| 84 | 3.0, and 6.0 degrees C. Configured hysteresis values will be rounded to those |
| 85 | limits. The chip supports only a single register to configure the hysteresis, |
| 86 | which applies to all limits. This register can be written by writing into |
| 87 | temp1_crit_hyst. Other hysteresis attributes are read-only. |
| 88 | |
| Clemens Ladisch | 2c6315d | 2011-02-16 08:02:38 -0500 | [diff] [blame] | 89 | If the BIOS has configured the sensor for automatic temperature management, it |
| 90 | is likely that it has locked the registers, i.e., that the temperature limits |
| 91 | cannot be changed. |
| 92 | |
| Guenter Roeck | 4453d73 | 2010-08-09 17:21:08 -0700 | [diff] [blame] | 93 | Sysfs entries |
| 94 | ------------- |
| 95 | |
| 96 | temp1_input Temperature (RO) |
| Clemens Ladisch | 2c6315d | 2011-02-16 08:02:38 -0500 | [diff] [blame] | 97 | temp1_min Minimum temperature (RO or RW) |
| 98 | temp1_max Maximum temperature (RO or RW) |
| 99 | temp1_crit Critical high temperature (RO or RW) |
| Guenter Roeck | 4453d73 | 2010-08-09 17:21:08 -0700 | [diff] [blame] | 100 | |
| Clemens Ladisch | 2c6315d | 2011-02-16 08:02:38 -0500 | [diff] [blame] | 101 | temp1_crit_hyst Critical hysteresis temperature (RO or RW) |
| Guenter Roeck | 4453d73 | 2010-08-09 17:21:08 -0700 | [diff] [blame] | 102 | temp1_max_hyst Maximum hysteresis temperature (RO) |
| 103 | |
| 104 | temp1_min_alarm Temperature low alarm |
| 105 | temp1_max_alarm Temperature high alarm |
| 106 | temp1_crit_alarm Temperature critical alarm |