1Kernel driver lm63 2================== 3 4Supported chips: 5 6 * National Semiconductor LM63 7 8 Prefix: 'lm63' 9 10 Addresses scanned: I2C 0x4c 11 12 Datasheet: Publicly available at the National Semiconductor website 13 14 http://www.national.com/pf/LM/LM63.html 15 16 * National Semiconductor LM64 17 18 Prefix: 'lm64' 19 20 Addresses scanned: I2C 0x18 and 0x4e 21 22 Datasheet: Publicly available at the National Semiconductor website 23 24 http://www.national.com/pf/LM/LM64.html 25 26 * National Semiconductor LM96163 27 28 Prefix: 'lm96163' 29 30 Addresses scanned: I2C 0x4c 31 32 Datasheet: Publicly available at the National Semiconductor website 33 34 http://www.national.com/pf/LM/LM96163.html 35 36 37Author: Jean Delvare <jdelvare@suse.de> 38 39Thanks go to Tyan and especially Alex Buckingham for setting up a remote 40access to their S4882 test platform for this driver. 41 42 http://www.tyan.com/ 43 44Description 45----------- 46 47The LM63 is a digital temperature sensor with integrated fan monitoring 48and control. 49 50The LM63 is basically an LM86 with fan speed monitoring and control 51capabilities added. It misses some of the LM86 features though: 52 53 - No low limit for local temperature. 54 - No critical limit for local temperature. 55 - Critical limit for remote temperature can be changed only once. We 56 will consider that the critical limit is read-only. 57 58The datasheet isn't very clear about what the tachometer reading is. 59 60An explanation from National Semiconductor: The two lower bits of the read 61value have to be masked out. The value is still 16 bit in width. 62 63All temperature values are given in degrees Celsius. Resolution is 1.0 64degree for the local temperature, 0.125 degree for the remote temperature. 65 66The fan speed is measured using a tachometer. Contrary to most chips which 67store the value in an 8-bit register and have a selectable clock divider 68to make sure that the result will fit in the register, the LM63 uses 16-bit 69value for measuring the speed of the fan. It can measure fan speeds down to 7083 RPM, at least in theory. 71 72Note that the pin used for fan monitoring is shared with an alert out 73function. Depending on how the board designer wanted to use the chip, fan 74speed monitoring will or will not be possible. The proper chip configuration 75is left to the BIOS, and the driver will blindly trust it. Only the original 76LM63 suffers from this limitation, the LM64 and LM96163 have separate pins 77for fan monitoring and alert out. On the LM64, monitoring is always enabled; 78on the LM96163 it can be disabled. 79 80A PWM output can be used to control the speed of the fan. The LM63 has two 81PWM modes: manual and automatic. Automatic mode is not fully implemented yet 82(you cannot define your custom PWM/temperature curve), and mode change isn't 83supported either. 84 85The lm63 driver will not update its values more frequently than configured with 86the update_interval sysfs attribute; reading them more often will do no harm, 87but will return 'old' values. Values in the automatic fan control lookup table 88(attributes pwm1_auto_*) have their own independent lifetime of 5 seconds. 89 90The LM64 is effectively an LM63 with GPIO lines. The driver does not 91support these GPIO lines at present. 92 93The LM96163 is an enhanced version of LM63 with improved temperature accuracy 94and better PWM resolution. For LM96163, the external temperature sensor type is 95configurable as CPU embedded diode(1) or 3904 transistor(2). 96