Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net
[linux-2.6.git] / Documentation / hwmon / jc42
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
54     Datasheet:
55         http://www.jedec.org/sites/default/files/docs/4_01_04R19.pdf
56
57 Author:
58         Guenter Roeck <guenter.roeck@ericsson.com>
59
60
61 Description
62 -----------
63
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
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
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
93 Sysfs entries
94 -------------
95
96 temp1_input             Temperature (RO)
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)
100
101 temp1_crit_hyst         Critical hysteresis temperature (RO or RW)
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