Based on kernel version 3.16. Page generated on 2014-08-06 21:39 EST.
1 Kernel driver lm87 2 ================== 3 4 Supported chips: 5 * National Semiconductor LM87 6 Prefix: 'lm87' 7 Addresses scanned: I2C 0x2c - 0x2e 8 Datasheet: http://www.national.com/pf/LM/LM87.html 9 * Analog Devices ADM1024 10 Prefix: 'adm1024' 11 Addresses scanned: I2C 0x2c - 0x2e 12 Datasheet: http://www.analog.com/en/prod/0,2877,ADM1024,00.html 13 14 Authors: 15 Frodo Looijaard <email@example.com>, 16 Philip Edelbrock <firstname.lastname@example.org>, 17 Mark Studebaker <email@example.com>, 18 Stephen Rousset <firstname.lastname@example.org>, 19 Dan Eaton <email@example.com>, 20 Jean Delvare <firstname.lastname@example.org>, 21 Original 2.6 port Jeff Oliver 22 23 Description 24 ----------- 25 26 This driver implements support for the National Semiconductor LM87 27 and the Analog Devices ADM1024. 28 29 The LM87 implements up to three temperature sensors, up to two fan 30 rotation speed sensors, up to seven voltage sensors, alarms, and some 31 miscellaneous stuff. The ADM1024 is fully compatible. 32 33 Temperatures are measured in degrees Celsius. Each input has a high 34 and low alarm settings. A high limit produces an alarm when the value 35 goes above it, and an alarm is also produced when the value goes below 36 the low limit. 37 38 Fan rotation speeds are reported in RPM (rotations per minute). An alarm is 39 triggered if the rotation speed has dropped below a programmable limit. Fan 40 readings can be divided by a programmable divider (1, 2, 4 or 8) to give 41 the readings more range or accuracy. Not all RPM values can accurately be 42 represented, so some rounding is done. With a divider of 2, the lowest 43 representable value is around 2600 RPM. 44 45 Voltage sensors (also known as IN sensors) report their values in 46 volts. An alarm is triggered if the voltage has crossed a programmable 47 minimum or maximum limit. Note that minimum in this case always means 48 'closest to zero'; this is important for negative voltage measurements. 49 50 If an alarm triggers, it will remain triggered until the hardware register 51 is read at least once. This means that the cause for the alarm may 52 already have disappeared! Note that in the current implementation, all 53 hardware registers are read whenever any data is read (unless it is less 54 than 1.0 seconds since the last update). This means that you can easily 55 miss once-only alarms. 56 57 The lm87 driver only updates its values each 1.0 seconds; reading it more 58 often will do no harm, but will return 'old' values. 59 60 61 Hardware Configurations 62 ----------------------- 63 64 The LM87 has four pins which can serve one of two possible functions, 65 depending on the hardware configuration. 66 67 Some functions share pins, so not all functions are available at the same 68 time. Which are depends on the hardware setup. This driver normally 69 assumes that firmware configured the chip correctly. Where this is not 70 the case, platform code must set the I2C client's platform_data to point 71 to a u8 value to be written to the channel register. 72 73 For reference, here is the list of exclusive functions: 74 - in0+in5 (default) or temp3 75 - fan1 (default) or in6 76 - fan2 (default) or in7 77 - VID lines (default) or IRQ lines (not handled by this driver)