Based on kernel version 3.12. Page generated on 2013-11-13 21:58 EST.
1 Kernel driver lm63 2 ================== 3 4 Supported chips: 5 * National Semiconductor LM63 6 Prefix: 'lm63' 7 Addresses scanned: I2C 0x4c 8 Datasheet: Publicly available at the National Semiconductor website 9 http://www.national.com/pf/LM/LM63.html 10 * National Semiconductor LM64 11 Prefix: 'lm64' 12 Addresses scanned: I2C 0x18 and 0x4e 13 Datasheet: Publicly available at the National Semiconductor website 14 http://www.national.com/pf/LM/LM64.html 15 * National Semiconductor LM96163 16 Prefix: 'lm96163' 17 Addresses scanned: I2C 0x4c 18 Datasheet: Publicly available at the National Semiconductor website 19 http://www.national.com/pf/LM/LM96163.html 20 21 Author: Jean Delvare <firstname.lastname@example.org> 22 23 Thanks go to Tyan and especially Alex Buckingham for setting up a remote 24 access to their S4882 test platform for this driver. 25 http://www.tyan.com/ 26 27 Description 28 ----------- 29 30 The LM63 is a digital temperature sensor with integrated fan monitoring 31 and control. 32 33 The LM63 is basically an LM86 with fan speed monitoring and control 34 capabilities added. It misses some of the LM86 features though: 35 - No low limit for local temperature. 36 - No critical limit for local temperature. 37 - Critical limit for remote temperature can be changed only once. We 38 will consider that the critical limit is read-only. 39 40 The datasheet isn't very clear about what the tachometer reading is. 41 42 An explanation from National Semiconductor: The two lower bits of the read 43 value have to be masked out. The value is still 16 bit in width. 44 45 All temperature values are given in degrees Celsius. Resolution is 1.0 46 degree for the local temperature, 0.125 degree for the remote temperature. 47 48 The fan speed is measured using a tachometer. Contrary to most chips which 49 store the value in an 8-bit register and have a selectable clock divider 50 to make sure that the result will fit in the register, the LM63 uses 16-bit 51 value for measuring the speed of the fan. It can measure fan speeds down to 52 83 RPM, at least in theory. 53 54 Note that the pin used for fan monitoring is shared with an alert out 55 function. Depending on how the board designer wanted to use the chip, fan 56 speed monitoring will or will not be possible. The proper chip configuration 57 is left to the BIOS, and the driver will blindly trust it. Only the original 58 LM63 suffers from this limitation, the LM64 and LM96163 have separate pins 59 for fan monitoring and alert out. On the LM64, monitoring is always enabled; 60 on the LM96163 it can be disabled. 61 62 A PWM output can be used to control the speed of the fan. The LM63 has two 63 PWM modes: manual and automatic. Automatic mode is not fully implemented yet 64 (you cannot define your custom PWM/temperature curve), and mode change isn't 65 supported either. 66 67 The lm63 driver will not update its values more frequently than configured with 68 the update_interval sysfs attribute; reading them more often will do no harm, 69 but will return 'old' values. Values in the automatic fan control lookup table 70 (attributes pwm1_auto_*) have their own independent lifetime of 5 seconds. 71 72 The LM64 is effectively an LM63 with GPIO lines. The driver does not 73 support these GPIO lines at present. 74 75 The LM96163 is an enhanced version of LM63 with improved temperature accuracy 76 and better PWM resolution. For LM96163, the external temperature sensor type is 77 configurable as CPU embedded diode(1) or 3904 transistor(2).