1Kernel driver lm85 2================== 3 4Supported chips: 5 * National Semiconductor LM85 (B and C versions) 6 Prefix: 'lm85' 7 Addresses scanned: I2C 0x2c, 0x2d, 0x2e 8 Datasheet: http://www.national.com/pf/LM/LM85.html 9 * Analog Devices ADM1027 10 Prefix: 'adm1027' 11 Addresses scanned: I2C 0x2c, 0x2d, 0x2e 12 Datasheet: http://www.onsemi.com/PowerSolutions/product.do?id=ADM1027 13 * Analog Devices ADT7463 14 Prefix: 'adt7463' 15 Addresses scanned: I2C 0x2c, 0x2d, 0x2e 16 Datasheet: http://www.onsemi.com/PowerSolutions/product.do?id=ADT7463 17 * Analog Devices ADT7468 18 Prefix: 'adt7468' 19 Addresses scanned: I2C 0x2c, 0x2d, 0x2e 20 Datasheet: http://www.onsemi.com/PowerSolutions/product.do?id=ADT7468 21 * SMSC EMC6D100, SMSC EMC6D101 22 Prefix: 'emc6d100' 23 Addresses scanned: I2C 0x2c, 0x2d, 0x2e 24 Datasheet: http://www.smsc.com/media/Downloads_Public/discontinued/6d100.pdf 25 * SMSC EMC6D102 26 Prefix: 'emc6d102' 27 Addresses scanned: I2C 0x2c, 0x2d, 0x2e 28 Datasheet: http://www.smsc.com/main/catalog/emc6d102.html 29 * SMSC EMC6D103 30 Prefix: 'emc6d103' 31 Addresses scanned: I2C 0x2c, 0x2d, 0x2e 32 Datasheet: http://www.smsc.com/main/catalog/emc6d103.html 33 * SMSC EMC6D103S 34 Prefix: 'emc6d103s' 35 Addresses scanned: I2C 0x2c, 0x2d, 0x2e 36 Datasheet: http://www.smsc.com/main/catalog/emc6d103s.html 37 38Authors: 39 Philip Pokorny <ppokorny@penguincomputing.com>, 40 Frodo Looijaard <frodol@dds.nl>, 41 Richard Barrington <rich_b_nz@clear.net.nz>, 42 Margit Schubert-While <margitsw@t-online.de>, 43 Justin Thiessen <jthiessen@penguincomputing.com> 44 45Description 46----------- 47 48This driver implements support for the National Semiconductor LM85 and 49compatible chips including the Analog Devices ADM1027, ADT7463, ADT7468 and 50SMSC EMC6D10x chips family. 51 52The LM85 uses the 2-wire interface compatible with the SMBUS 2.0 53specification. Using an analog to digital converter it measures three (3) 54temperatures and five (5) voltages. It has four (4) 16-bit counters for 55measuring fan speed. Five (5) digital inputs are provided for sampling the 56VID signals from the processor to the VRM. Lastly, there are three (3) PWM 57outputs that can be used to control fan speed. 58 59The voltage inputs have internal scaling resistors so that the following 60voltage can be measured without external resistors: 61 62 2.5V, 3.3V, 5V, 12V, and CPU core voltage (2.25V) 63 64The temperatures measured are one internal diode, and two remote diodes. 65Remote 1 is generally the CPU temperature. These inputs are designed to 66measure a thermal diode like the one in a Pentium 4 processor in a socket 67423 or socket 478 package. They can also measure temperature using a 68transistor like the 2N3904. 69 70A sophisticated control system for the PWM outputs is designed into the 71LM85 that allows fan speed to be adjusted automatically based on any of the 72three temperature sensors. Each PWM output is individually adjustable and 73programmable. Once configured, the LM85 will adjust the PWM outputs in 74response to the measured temperatures without further host intervention. 75This feature can also be disabled for manual control of the PWM's. 76 77Each of the measured inputs (voltage, temperature, fan speed) has 78corresponding high/low limit values. The LM85 will signal an ALARM if any 79measured value exceeds either limit. 80 81The LM85 samples all inputs continuously. The lm85 driver will not read 82the registers more often than once a second. Further, configuration data is 83only read once each 5 minutes. There is twice as much config data as 84measurements, so this would seem to be a worthwhile optimization. 85 86Special Features 87---------------- 88 89The LM85 has four fan speed monitoring modes. The ADM1027 has only two. 90Both have special circuitry to compensate for PWM interactions with the 91TACH signal from the fans. The ADM1027 can be configured to measure the 92speed of a two wire fan, but the input conditioning circuitry is different 93for 3-wire and 2-wire mode. For this reason, the 2-wire fan modes are not 94exposed to user control. The BIOS should initialize them to the correct 95mode. If you've designed your own ADM1027, you'll have to modify the 96init_client function and add an insmod parameter to set this up. 97 98To smooth the response of fans to changes in temperature, the LM85 has an 99optional filter for smoothing temperatures. The ADM1027 has the same 100config option but uses it to rate limit the changes to fan speed instead. 101 102The ADM1027, ADT7463 and ADT7468 have a 10-bit ADC and can therefore 103measure temperatures with 0.25 degC resolution. They also provide an offset 104to the temperature readings that is automatically applied during 105measurement. This offset can be used to zero out any errors due to traces 106and placement. The documentation says that the offset is in 0.25 degC 107steps, but in initial testing of the ADM1027 it was 1.00 degC steps. Analog 108Devices has confirmed this "bug". The ADT7463 is reported to work as 109described in the documentation. The current lm85 driver does not show the 110offset register. 111 112The ADT7468 has a high-frequency PWM mode, where all PWM outputs are 113driven by a 22.5 kHz clock. This is a global mode, not per-PWM output, 114which means that setting any PWM frequency above 11.3 kHz will switch 115all 3 PWM outputs to a 22.5 kHz frequency. Conversely, setting any PWM 116frequency below 11.3 kHz will switch all 3 PWM outputs to a frequency 117between 10 and 100 Hz, which can then be tuned separately. 118 119See the vendor datasheets for more information. There is application note 120from National (AN-1260) with some additional information about the LM85. 121The Analog Devices datasheet is very detailed and describes a procedure for 122determining an optimal configuration for the automatic PWM control. 123 124The SMSC EMC6D100 & EMC6D101 monitor external voltages, temperatures, and 125fan speeds. They use this monitoring capability to alert the system to out 126of limit conditions and can automatically control the speeds of multiple 127fans in a PC or embedded system. The EMC6D101, available in a 24-pin SSOP 128package, and the EMC6D100, available in a 28-pin SSOP package, are designed 129to be register compatible. The EMC6D100 offers all the features of the 130EMC6D101 plus additional voltage monitoring and system control features. 131Unfortunately it is not possible to distinguish between the package 132versions on register level so these additional voltage inputs may read 133zero. EMC6D102 and EMC6D103 feature additional ADC bits thus extending precision 134of voltage and temperature channels. 135 136SMSC EMC6D103S is similar to EMC6D103, but does not support pwm#_auto_pwm_minctl 137and temp#_auto_temp_off. 138 139Hardware Configurations 140----------------------- 141 142The LM85 can be jumpered for 3 different SMBus addresses. There are 143no other hardware configuration options for the LM85. 144 145The lm85 driver detects both LM85B and LM85C revisions of the chip. See the 146datasheet for a complete description of the differences. Other than 147identifying the chip, the driver behaves no differently with regard to 148these two chips. The LM85B is recommended for new designs. 149 150The ADM1027, ADT7463 and ADT7468 chips have an optional SMBALERT output 151that can be used to signal the chipset in case a limit is exceeded or the 152temperature sensors fail. Individual sensor interrupts can be masked so 153they won't trigger SMBALERT. The SMBALERT output if configured replaces one 154of the other functions (PWM2 or IN0). This functionality is not implemented 155in current driver. 156 157The ADT7463 and ADT7468 also have an optional THERM output/input which can 158be connected to the processor PROC_HOT output. If available, the autofan 159control dynamic Tmin feature can be enabled to keep the system temperature 160within spec (just?!) with the least possible fan noise. 161 162Configuration Notes 163------------------- 164 165Besides standard interfaces driver adds following: 166 167* Temperatures and Zones 168 169Each temperature sensor is associated with a Zone. There are three 170sensors and therefore three zones (# 1, 2 and 3). Each zone has the following 171temperature configuration points: 172 173* temp#_auto_temp_off - temperature below which fans should be off or spinning very low. 174* temp#_auto_temp_min - temperature over which fans start to spin. 175* temp#_auto_temp_max - temperature when fans spin at full speed. 176* temp#_auto_temp_crit - temperature when all fans will run full speed. 177 178* PWM Control 179 180There are three PWM outputs. The LM85 datasheet suggests that the 181pwm3 output control both fan3 and fan4. Each PWM can be individually 182configured and assigned to a zone for its control value. Each PWM can be 183configured individually according to the following options. 184 185* pwm#_auto_pwm_min - this specifies the PWM value for temp#_auto_temp_off 186 temperature. (PWM value from 0 to 255) 187 188* pwm#_auto_pwm_minctl - this flags selects for temp#_auto_temp_off temperature 189 the behaviour of fans. Write 1 to let fans spinning at 190 pwm#_auto_pwm_min or write 0 to let them off. 191 192NOTE: It has been reported that there is a bug in the LM85 that causes the flag 193to be associated with the zones not the PWMs. This contradicts all the 194published documentation. Setting pwm#_min_ctl in this case actually affects all 195PWMs controlled by zone '#'. 196 197* PWM Controlling Zone selection 198 199* pwm#_auto_channels - controls zone that is associated with PWM 200 201Configuration choices: 202 203 Value Meaning 204 ------ ------------------------------------------------ 205 1 Controlled by Zone 1 206 2 Controlled by Zone 2 207 3 Controlled by Zone 3 208 23 Controlled by higher temp of Zone 2 or 3 209 123 Controlled by highest temp of Zone 1, 2 or 3 210 0 PWM always 0% (off) 211 -1 PWM always 100% (full on) 212 -2 Manual control (write to 'pwm#' to set) 213 214The National LM85's have two vendor specific configuration 215features. Tach. mode and Spinup Control. For more details on these, 216see the LM85 datasheet or Application Note AN-1260. These features 217are not currently supported by the lm85 driver. 218 219The Analog Devices ADM1027 has several vendor specific enhancements. 220The number of pulses-per-rev of the fans can be set, Tach monitoring 221can be optimized for PWM operation, and an offset can be applied to 222the temperatures to compensate for systemic errors in the 223measurements. These features are not currently supported by the lm85 224driver. 225 226In addition to the ADM1027 features, the ADT7463 and ADT7468 also have 227Tmin control and THERM asserted counts. Automatic Tmin control acts to 228adjust the Tmin value to maintain the measured temperature sensor at a 229specified temperature. There isn't much documentation on this feature in 230the ADT7463 data sheet. This is not supported by current driver. 231